Snap for 11051817 from 62618d11a2e7875c438c5131abb6847da26aa6f4 to mainline-appsearch-releaseaml_ase_341510000aml_ase_341410000aml_ase_341310010android14-mainline-appsearch-release

Change-Id: Iabe954f99966dc27da282d1b627ac7a82d3082d1

113 files changed, 6822 insertions, 1464 deletions

diff --git a/.github/workflows/code-check.yml b/.github/workflows/code-check.yml
index b6cf8fd..021b1e4 100644
--- a/.github/workflows/code-check.yml
+++ b/.github/workflows/code-check.yml
@@ -14,6 +14,10 @@ jobs:
   check:
     name: Check Code
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
+      fail-fast: false
 
     steps:
     - name: Check out from Git
diff --git a/.github/workflows/python-build-test.yml b/.github/workflows/python-build-test.yml
index 3f20093..4cc3e73 100644
--- a/.github/workflows/python-build-test.yml
+++ b/.github/workflows/python-build-test.yml
@@ -12,10 +12,10 @@ permissions:
 
 jobs:
   build:
-
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
         python-version: ["3.8", "3.9", "3.10", "3.11"]
       fail-fast: false
 
@@ -41,11 +41,13 @@ jobs:
       run: |
         inv build
         inv build.mkdocs
+
   build-rust:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [ "3.8", "3.9", "3.10" ]
+        python-version: [ "3.8", "3.9", "3.10", "3.11" ]
+        rust-version: [ "1.70.0", "stable" ]
       fail-fast: false
     steps:
       - name: Check out from Git
@@ -62,9 +64,17 @@ jobs:
         uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           components: clippy,rustfmt
-      - name: Rust Lints
-        run: cd rust && cargo fmt --check && cargo clippy --all-targets -- --deny warnings
+          toolchain: ${{ matrix.rust-version }}
+      - name: Check License Headers
+        run: cd rust && cargo run --features dev-tools --bin file-header check-all
       - name: Rust Build
-        run: cd rust && cargo build --all-targets
+        run: cd rust && cargo build --all-targets && cargo build --all-features --all-targets
+      # Lints after build so what clippy needs is already built
+      - name: Rust Lints
+        run: cd rust && cargo fmt --check && cargo clippy --all-targets -- --deny warnings && cargo clippy --all-features --all-targets -- --deny warnings
       - name: Rust Tests
-        run: cd rust && cargo test
\ No newline at end of file
+        run: cd rust && cargo test
+      # At some point, hook up publishing the binary. For now, just make sure it builds.
+      # Once we're ready to publish binaries, this should be built with `--release`.
+      - name: Build Bumble CLI
+        run: cd rust && cargo build --features bumble-tools --bin bumble
\ No newline at end of file
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 864fe69..57e682a 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -39,10 +39,12 @@
         "libusb",
         "MITM",
         "NDIS",
+        "netsim",
         "NONBLOCK",
         "NONCONN",
         "OXIMETER",
         "popleft",
+        "protobuf",
         "psms",
         "pyee",
         "pyusb",
diff --git a/METADATA b/METADATA
index 30444f1..48086d7 100644
--- a/METADATA
+++ b/METADATA
@@ -11,7 +11,7 @@ third_party {
     type: GIT
     value: "https://github.com/google/bumble"
   }
-  version: "c66b357de6908cf3680d83a73c6744451e2d0fa0"
-  last_upgrade_date { year: 2022 month: 7 day: 25 }
+  version: "783b2d70a517a4c5fd828a0f6b8b2a46fe8750c5"
+  last_upgrade_date { year: 2023 month: 9 day: 12 }
   license_type: NOTICE
 }
diff --git a/apps/console.py b/apps/console.py
index 0ea9e5b..9a529dd 100644
--- a/apps/console.py
+++ b/apps/console.py
@@ -1172,7 +1172,7 @@ class ScanResult:
             name = ''
 
         # Remove any '/P' qualifier suffix from the address string
-        address_str = str(self.address).replace('/P', '')
+        address_str = self.address.to_string(with_type_qualifier=False)
 
         # RSSI bar
         bar_string = rssi_bar(self.rssi)
diff --git a/apps/controller_info.py b/apps/controller_info.py
index 4707983..5be4f3d 100644
--- a/apps/controller_info.py
+++ b/apps/controller_info.py
@@ -63,7 +63,8 @@ async def get_classic_info(host):
         if command_succeeded(response):
             print()
             print(
-                color('Classic Address:', 'yellow'), response.return_parameters.bd_addr
+                color('Classic Address:', 'yellow'),
+                response.return_parameters.bd_addr.to_string(False),
             )
 
     if host.supports_command(HCI_READ_LOCAL_NAME_COMMAND):
diff --git a/apps/l2cap_bridge.py b/apps/l2cap_bridge.py
index 17623e4..83379a0 100644
--- a/apps/l2cap_bridge.py
+++ b/apps/l2cap_bridge.py
@@ -105,7 +105,7 @@ class ServerBridge:
                             asyncio.create_task(self.pipe.l2cap_channel.disconnect())
 
                     def data_received(self, data):
-                        print(f'<<< Received on TCP: {len(data)}')
+                        print(color(f'<<< [TCP DATA]: {len(data)} bytes', 'blue'))
                         self.pipe.l2cap_channel.write(data)
 
                 try:
@@ -123,6 +123,7 @@ class ServerBridge:
                     await self.l2cap_channel.disconnect()
 
             def on_l2cap_close(self):
+                print(color('*** L2CAP channel closed', 'red'))
                 self.l2cap_channel = None
                 if self.tcp_transport is not None:
                     self.tcp_transport.close()
diff --git a/apps/pandora_server.py b/apps/pandora_server.py
index b577f82..16bc211 100644
--- a/apps/pandora_server.py
+++ b/apps/pandora_server.py
@@ -3,7 +3,7 @@ import click
 import logging
 import json
 
-from bumble.pandora import PandoraDevice, serve
+from bumble.pandora import PandoraDevice, Config, serve
 from typing import Dict, Any
 
 BUMBLE_SERVER_GRPC_PORT = 7999
@@ -29,12 +29,14 @@ def main(grpc_port: int, rootcanal_port: int, transport: str, config: str) -> No
         transport = transport.replace('<rootcanal-port>', str(rootcanal_port))
 
     bumble_config = retrieve_config(config)
-    if 'transport' not in bumble_config.keys():
-        bumble_config.update({'transport': transport})
+    bumble_config.setdefault('transport', transport)
     device = PandoraDevice(bumble_config)
 
+    server_config = Config()
+    server_config.load_from_dict(bumble_config.get('server', {}))
+
     logging.basicConfig(level=logging.DEBUG)
-    asyncio.run(serve(device, port=grpc_port))
+    asyncio.run(serve(device, config=server_config, port=grpc_port))
 
 
 def retrieve_config(config: str) -> Dict[str, Any]:
diff --git a/apps/show.py b/apps/show.py
index bf01ead..f849e3a 100644
--- a/apps/show.py
+++ b/apps/show.py
@@ -102,9 +102,21 @@ class SnoopPacketReader:
     default='h4',
     help='Format of the input file',
 )
+@click.option(
+    '--vendors',
+    type=click.Choice(['android', 'zephyr']),
+    multiple=True,
+    help='Support vendor-specific commands (list one or more)',
+)
 @click.argument('filename')
 # pylint: disable=redefined-builtin
-def main(format, filename):
+def main(format, vendors, filename):
+    for vendor in vendors:
+        if vendor == 'android':
+            import bumble.vendor.android.hci
+        elif vendor == 'zephyr':
+            import bumble.vendor.zephyr.hci
+
     input = open(filename, 'rb')
     if format == 'h4':
         packet_reader = PacketReader(input)
@@ -124,7 +136,6 @@ def main(format, filename):
             if packet is None:
                 break
             tracer.trace(hci.HCI_Packet.from_bytes(packet), direction)
-
         except Exception as error:
             print(color(f'!!! {error}', 'red'))
 
diff --git a/apps/speaker/speaker.css b/apps/speaker/speaker.css
index 075068b..dd4c799 100644
--- a/apps/speaker/speaker.css
+++ b/apps/speaker/speaker.css
@@ -56,7 +56,7 @@ body, h1, h2, h3, h4, h5, h6 {
     border-radius: 4px;
     padding: 4px;
     margin: 6px;
-    margin-left: 0px;
+    margin-left: 0;
 }
 
 th, td {
@@ -65,7 +65,7 @@ th, td {
 }
 
 .properties td:nth-child(even) {
-    background-color: #D6EEEE;
+    background-color: #d6eeee;
     font-family: monospace;
 }
 
diff --git a/apps/speaker/speaker.html b/apps/speaker/speaker.html
index f68abcc..550049b 100644
--- a/apps/speaker/speaker.html
+++ b/apps/speaker/speaker.html
@@ -2,7 +2,7 @@
 <html>
 <head>
   <title>Bumble Speaker</title>
-  <script type="text/javascript" src="speaker.js"></script>
+  <script src="speaker.js"></script>
   <link rel="stylesheet" href="speaker.css">
 </head>
 <body>
diff --git a/apps/speaker/speaker.py b/apps/speaker/speaker.py
index a2907d4..e451c04 100644
--- a/apps/speaker/speaker.py
+++ b/apps/speaker/speaker.py
@@ -195,7 +195,7 @@ class WebSocketOutput(QueuedOutput):
         except HCI_StatusError:
             pass
         peer_name = '' if connection.peer_name is None else connection.peer_name
-        peer_address = str(connection.peer_address).replace('/P', '')
+        peer_address = connection.peer_address.to_string(False)
         await self.send_message(
             'connection',
             peer_address=peer_address,
@@ -228,10 +228,11 @@ class FfplayOutput(QueuedOutput):
     subprocess: Optional[asyncio.subprocess.Process]
     ffplay_task: Optional[asyncio.Task]
 
-    def __init__(self) -> None:
-        super().__init__(AacAudioExtractor())
+    def __init__(self, codec: str) -> None:
+        super().__init__(AudioExtractor.create(codec))
         self.subprocess = None
         self.ffplay_task = None
+        self.codec = codec
 
     async def start(self):
         if self.started:
@@ -240,7 +241,7 @@ class FfplayOutput(QueuedOutput):
         await super().start()
 
         self.subprocess = await asyncio.create_subprocess_shell(
-            'ffplay -acodec aac pipe:0',
+            f'ffplay -f {self.codec} pipe:0',
             stdin=asyncio.subprocess.PIPE,
             stdout=asyncio.subprocess.PIPE,
             stderr=asyncio.subprocess.PIPE,
@@ -375,7 +376,7 @@ class UiServer:
         if connection := self.speaker().connection:
             await self.send_message(
                 'connection',
-                peer_address=str(connection.peer_address).replace('/P', ''),
+                peer_address=connection.peer_address.to_string(False),
                 peer_name=connection.peer_name,
             )
 
@@ -419,7 +420,7 @@ class Speaker:
         self.outputs = []
         for output in outputs:
             if output == '@ffplay':
-                self.outputs.append(FfplayOutput())
+                self.outputs.append(FfplayOutput(codec))
                 continue
 
             # Default to FileOutput
@@ -708,17 +709,6 @@ def speaker(
 ):
     """Run the speaker."""
 
-    # ffplay only works with AAC for now
-    if codec != 'aac' and '@ffplay' in output:
-        print(
-            color(
-                f'{codec} not supported with @ffplay output, '
-                '@ffplay output will be skipped',
-                'yellow',
-            )
-        )
-        output = list(filter(lambda x: x != '@ffplay', output))
-
     if '@ffplay' in output:
         # Check if ffplay is installed
         try:
diff --git a/bumble/att.py b/bumble/att.py
index 55ae8a5..db8d2ba 100644
--- a/bumble/att.py
+++ b/bumble/att.py
@@ -23,13 +23,14 @@
 # Imports
 # -----------------------------------------------------------------------------
 from __future__ import annotations
+import enum
 import functools
 import struct
 from pyee import EventEmitter
-from typing import Dict, Type, TYPE_CHECKING
+from typing import Dict, Type, List, Protocol, Union, Optional, Any, TYPE_CHECKING
 
-from bumble.core import UUID, name_or_number, get_dict_key_by_value, ProtocolError
-from bumble.hci import HCI_Object, key_with_value, HCI_Constant
+from bumble.core import UUID, name_or_number, ProtocolError
+from bumble.hci import HCI_Object, key_with_value
 from bumble.colors import color
 
 if TYPE_CHECKING:
@@ -182,6 +183,7 @@ UUID_2_FIELD_SPEC    = lambda x, y: UUID.parse_uuid_2(x, y)  # noqa: E731
 # pylint: enable=line-too-long
 # pylint: disable=invalid-name
 
+
 # -----------------------------------------------------------------------------
 # Exceptions
 # -----------------------------------------------------------------------------
@@ -209,7 +211,7 @@ class ATT_PDU:
 
     pdu_classes: Dict[int, Type[ATT_PDU]] = {}
     op_code = 0
-    name = None
+    name: str
 
     @staticmethod
     def from_bytes(pdu):
@@ -720,47 +722,67 @@ class ATT_Handle_Value_Confirmation(ATT_PDU):
 
 
 # -----------------------------------------------------------------------------
-class Attribute(EventEmitter):
-    # Permission flags
-    READABLE = 0x01
-    WRITEABLE = 0x02
-    READ_REQUIRES_ENCRYPTION = 0x04
-    WRITE_REQUIRES_ENCRYPTION = 0x08
-    READ_REQUIRES_AUTHENTICATION = 0x10
-    WRITE_REQUIRES_AUTHENTICATION = 0x20
-    READ_REQUIRES_AUTHORIZATION = 0x40
-    WRITE_REQUIRES_AUTHORIZATION = 0x80
-
-    PERMISSION_NAMES = {
-        READABLE: 'READABLE',
-        WRITEABLE: 'WRITEABLE',
-        READ_REQUIRES_ENCRYPTION: 'READ_REQUIRES_ENCRYPTION',
-        WRITE_REQUIRES_ENCRYPTION: 'WRITE_REQUIRES_ENCRYPTION',
-        READ_REQUIRES_AUTHENTICATION: 'READ_REQUIRES_AUTHENTICATION',
-        WRITE_REQUIRES_AUTHENTICATION: 'WRITE_REQUIRES_AUTHENTICATION',
-        READ_REQUIRES_AUTHORIZATION: 'READ_REQUIRES_AUTHORIZATION',
-        WRITE_REQUIRES_AUTHORIZATION: 'WRITE_REQUIRES_AUTHORIZATION',
-    }
+class ConnectionValue(Protocol):
+    def read(self, connection) -> bytes:
+        ...
 
-    @staticmethod
-    def string_to_permissions(permissions_str: str):
-        try:
-            return functools.reduce(
-                lambda x, y: x | get_dict_key_by_value(Attribute.PERMISSION_NAMES, y),
-                permissions_str.split(","),
-                0,
-            )
-        except TypeError as exc:
-            raise TypeError(
-                f"Attribute::permissions error:\nExpected a string containing any of the keys, separated by commas: {','.join(Attribute.PERMISSION_NAMES.values())}\nGot: {permissions_str}"
-            ) from exc
+    def write(self, connection, value: bytes) -> None:
+        ...
 
-    def __init__(self, attribute_type, permissions, value=b''):
+
+# -----------------------------------------------------------------------------
+class Attribute(EventEmitter):
+    class Permissions(enum.IntFlag):
+        READABLE = 0x01
+        WRITEABLE = 0x02
+        READ_REQUIRES_ENCRYPTION = 0x04
+        WRITE_REQUIRES_ENCRYPTION = 0x08
+        READ_REQUIRES_AUTHENTICATION = 0x10
+        WRITE_REQUIRES_AUTHENTICATION = 0x20
+        READ_REQUIRES_AUTHORIZATION = 0x40
+        WRITE_REQUIRES_AUTHORIZATION = 0x80
+
+        @classmethod
+        def from_string(cls, permissions_str: str) -> Attribute.Permissions:
+            try:
+                return functools.reduce(
+                    lambda x, y: x | Attribute.Permissions[y],
+                    permissions_str.replace('|', ',').split(","),
+                    Attribute.Permissions(0),
+                )
+            except TypeError as exc:
+                # The check for `p.name is not None` here is needed because for InFlag
+                # enums, the .name property can be None, when the enum value is 0,
+                # so the type hint for .name is Optional[str].
+                enum_list: List[str] = [p.name for p in cls if p.name is not None]
+                enum_list_str = ",".join(enum_list)
+                raise TypeError(
+                    f"Attribute::permissions error:\nExpected a string containing any of the keys, separated by commas: {enum_list_str  }\nGot: {permissions_str}"
+                ) from exc
+
+    # Permission flags(legacy-use only)
+    READABLE = Permissions.READABLE
+    WRITEABLE = Permissions.WRITEABLE
+    READ_REQUIRES_ENCRYPTION = Permissions.READ_REQUIRES_ENCRYPTION
+    WRITE_REQUIRES_ENCRYPTION = Permissions.WRITE_REQUIRES_ENCRYPTION
+    READ_REQUIRES_AUTHENTICATION = Permissions.READ_REQUIRES_AUTHENTICATION
+    WRITE_REQUIRES_AUTHENTICATION = Permissions.WRITE_REQUIRES_AUTHENTICATION
+    READ_REQUIRES_AUTHORIZATION = Permissions.READ_REQUIRES_AUTHORIZATION
+    WRITE_REQUIRES_AUTHORIZATION = Permissions.WRITE_REQUIRES_AUTHORIZATION
+
+    value: Union[str, bytes, ConnectionValue]
+
+    def __init__(
+        self,
+        attribute_type: Union[str, bytes, UUID],
+        permissions: Union[str, Attribute.Permissions],
+        value: Union[str, bytes, ConnectionValue] = b'',
+    ) -> None:
         EventEmitter.__init__(self)
         self.handle = 0
         self.end_group_handle = 0
         if isinstance(permissions, str):
-            self.permissions = self.string_to_permissions(permissions)
+            self.permissions = Attribute.Permissions.from_string(permissions)
         else:
             self.permissions = permissions
 
@@ -778,22 +800,26 @@ class Attribute(EventEmitter):
         else:
             self.value = value
 
-    def encode_value(self, value):
+    def encode_value(self, value: Any) -> bytes:
         return value
 
-    def decode_value(self, value_bytes):
+    def decode_value(self, value_bytes: bytes) -> Any:
         return value_bytes
 
-    def read_value(self, connection: Connection):
+    def read_value(self, connection: Optional[Connection]) -> bytes:
         if (
-            self.permissions & self.READ_REQUIRES_ENCRYPTION
-        ) and not connection.encryption:
+            (self.permissions & self.READ_REQUIRES_ENCRYPTION)
+            and connection is not None
+            and not connection.encryption
+        ):
             raise ATT_Error(
                 error_code=ATT_INSUFFICIENT_ENCRYPTION_ERROR, att_handle=self.handle
             )
         if (
-            self.permissions & self.READ_REQUIRES_AUTHENTICATION
-        ) and not connection.authenticated:
+            (self.permissions & self.READ_REQUIRES_AUTHENTICATION)
+            and connection is not None
+            and not connection.authenticated
+        ):
             raise ATT_Error(
                 error_code=ATT_INSUFFICIENT_AUTHENTICATION_ERROR, att_handle=self.handle
             )
@@ -803,9 +829,9 @@ class Attribute(EventEmitter):
                 error_code=ATT_INSUFFICIENT_AUTHORIZATION_ERROR, att_handle=self.handle
             )
 
-        if read := getattr(self.value, 'read', None):
+        if hasattr(self.value, 'read'):
             try:
-                value = read(connection)  # pylint: disable=not-callable
+                value = self.value.read(connection)
             except ATT_Error as error:
                 raise ATT_Error(
                     error_code=error.error_code, att_handle=self.handle
@@ -815,7 +841,7 @@ class Attribute(EventEmitter):
 
         return self.encode_value(value)
 
-    def write_value(self, connection: Connection, value_bytes):
+    def write_value(self, connection: Connection, value_bytes: bytes) -> None:
         if (
             self.permissions & self.WRITE_REQUIRES_ENCRYPTION
         ) and not connection.encryption:
@@ -836,9 +862,9 @@ class Attribute(EventEmitter):
 
         value = self.decode_value(value_bytes)
 
-        if write := getattr(self.value, 'write', None):
+        if hasattr(self.value, 'write'):
             try:
-                write(connection, value)  # pylint: disable=not-callable
+                self.value.write(connection, value)  # pylint: disable=not-callable
             except ATT_Error as error:
                 raise ATT_Error(
                     error_code=error.error_code, att_handle=self.handle
diff --git a/bumble/controller.py b/bumble/controller.py
index 688fcd7..9b2960a 100644
--- a/bumble/controller.py
+++ b/bumble/controller.py
@@ -15,6 +15,8 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
+
 import logging
 import asyncio
 import itertools
@@ -58,8 +60,10 @@ from bumble.hci import (
     HCI_Packet,
     HCI_Role_Change_Event,
 )
-from typing import Optional, Union, Dict
+from typing import Optional, Union, Dict, TYPE_CHECKING
 
+if TYPE_CHECKING:
+    from bumble.transport.common import TransportSink, TransportSource
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -104,7 +108,7 @@ class Controller:
         self,
         name,
         host_source=None,
-        host_sink=None,
+        host_sink: Optional[TransportSink] = None,
         link=None,
         public_address: Optional[Union[bytes, str, Address]] = None,
     ):
@@ -188,6 +192,8 @@ class Controller:
         if link:
             link.add_controller(self)
 
+        self.terminated = asyncio.get_running_loop().create_future()
+
     @property
     def host(self):
         return self.hci_sink
@@ -288,10 +294,9 @@ class Controller:
         if self.host:
             self.host.on_packet(packet.to_bytes())
 
-    # This method allow the controller to emulate the same API as a transport source
+    # This method allows the controller to emulate the same API as a transport source
     async def wait_for_termination(self):
-        # For now, just wait forever
-        await asyncio.get_running_loop().create_future()
+        await self.terminated
 
     ############################################################
     # Link connections
diff --git a/bumble/core.py b/bumble/core.py
index 2e3f4af..4a67d6e 100644
--- a/bumble/core.py
+++ b/bumble/core.py
@@ -78,7 +78,13 @@ def get_dict_key_by_value(dictionary, value):
 class BaseError(Exception):
     """Base class for errors with an error code, error name and namespace"""
 
-    def __init__(self, error_code, error_namespace='', error_name='', details=''):
+    def __init__(
+        self,
+        error_code: Optional[int],
+        error_namespace: str = '',
+        error_name: str = '',
+        details: str = '',
+    ):
         super().__init__()
         self.error_code = error_code
         self.error_namespace = error_namespace
@@ -90,12 +96,14 @@ class BaseError(Exception):
             namespace = f'{self.error_namespace}/'
         else:
             namespace = ''
-        if self.error_name:
-            name = f'{self.error_name} [0x{self.error_code:X}]'
-        else:
-            name = f'0x{self.error_code:X}'
+        error_text = {
+            (True, True): f'{self.error_name} [0x{self.error_code:X}]',
+            (True, False): self.error_name,
+            (False, True): f'0x{self.error_code:X}',
+            (False, False): '',
+        }[(self.error_name != '', self.error_code is not None)]
 
-        return f'{type(self).__name__}({namespace}{name})'
+        return f'{type(self).__name__}({namespace}{error_text})'
 
 
 class ProtocolError(BaseError):
@@ -134,6 +142,10 @@ class ConnectionError(BaseError):  # pylint: disable=redefined-builtin
         self.peer_address = peer_address
 
 
+class ConnectionParameterUpdateError(BaseError):
+    """Connection Parameter Update Error"""
+
+
 # -----------------------------------------------------------------------------
 # UUID
 #
diff --git a/bumble/crypto.py b/bumble/crypto.py
index 757594f..852c675 100644
--- a/bumble/crypto.py
+++ b/bumble/crypto.py
@@ -23,22 +23,18 @@
 # -----------------------------------------------------------------------------
 import logging
 import operator
-import platform
-
-if platform.system() != 'Emscripten':
-    import secrets
-    from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-    from cryptography.hazmat.primitives.asymmetric.ec import (
-        generate_private_key,
-        ECDH,
-        EllipticCurvePublicNumbers,
-        EllipticCurvePrivateNumbers,
-        SECP256R1,
-    )
-    from cryptography.hazmat.primitives import cmac
-else:
-    # TODO: implement stubs
-    pass
+
+import secrets
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+from cryptography.hazmat.primitives.asymmetric.ec import (
+    generate_private_key,
+    ECDH,
+    EllipticCurvePublicNumbers,
+    EllipticCurvePrivateNumbers,
+    SECP256R1,
+)
+from cryptography.hazmat.primitives import cmac
+
 
 # -----------------------------------------------------------------------------
 # Logging
diff --git a/bumble/device.py b/bumble/device.py
index 6ab0a12..b01dc58 100644
--- a/bumble/device.py
+++ b/bumble/device.py
@@ -23,7 +23,18 @@ import asyncio
 import logging
 from contextlib import asynccontextmanager, AsyncExitStack
 from dataclasses import dataclass
-from typing import Any, Callable, ClassVar, Dict, List, Optional, Tuple, Type, Union
+from typing import (
+    Any,
+    Callable,
+    ClassVar,
+    Dict,
+    List,
+    Optional,
+    Tuple,
+    Type,
+    Union,
+    TYPE_CHECKING,
+)
 
 from .colors import color
 from .att import ATT_CID, ATT_DEFAULT_MTU, ATT_PDU
@@ -130,6 +141,7 @@ from .core import (
     BT_LE_TRANSPORT,
     BT_PERIPHERAL_ROLE,
     AdvertisingData,
+    ConnectionParameterUpdateError,
     CommandTimeoutError,
     ConnectionPHY,
     InvalidStateError,
@@ -152,6 +164,9 @@ from . import sdp
 from . import l2cap
 from . import core
 
+if TYPE_CHECKING:
+    from .transport.common import TransportSource, TransportSink
+
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -652,7 +667,7 @@ class Connection(CompositeEventEmitter):
     def is_incomplete(self) -> bool:
         return self.handle is None
 
-    def send_l2cap_pdu(self, cid, pdu):
+    def send_l2cap_pdu(self, cid: int, pdu: bytes) -> None:
         self.device.send_l2cap_pdu(self.handle, cid, pdu)
 
     def create_l2cap_connector(self, psm):
@@ -709,6 +724,7 @@ class Connection(CompositeEventEmitter):
         connection_interval_max,
         max_latency,
         supervision_timeout,
+        use_l2cap=False,
     ):
         return await self.device.update_connection_parameters(
             self,
@@ -716,6 +732,7 @@ class Connection(CompositeEventEmitter):
             connection_interval_max,
             max_latency,
             supervision_timeout,
+            use_l2cap=use_l2cap,
         )
 
     async def set_phy(self, tx_phys=None, rx_phys=None, phy_options=None):
@@ -942,7 +959,13 @@ class Device(CompositeEventEmitter):
             pass
 
     @classmethod
-    def with_hci(cls, name, address, hci_source, hci_sink):
+    def with_hci(
+        cls,
+        name: str,
+        address: Address,
+        hci_source: TransportSource,
+        hci_sink: TransportSink,
+    ) -> Device:
         '''
         Create a Device instance with a Host configured to communicate with a controller
         through an HCI source/sink
@@ -951,18 +974,25 @@ class Device(CompositeEventEmitter):
         return cls(name=name, address=address, host=host)
 
     @classmethod
-    def from_config_file(cls, filename):
+    def from_config_file(cls, filename: str) -> Device:
         config = DeviceConfiguration()
         config.load_from_file(filename)
         return cls(config=config)
 
     @classmethod
-    def from_config_with_hci(cls, config, hci_source, hci_sink):
+    def from_config_with_hci(
+        cls,
+        config: DeviceConfiguration,
+        hci_source: TransportSource,
+        hci_sink: TransportSink,
+    ) -> Device:
         host = Host(controller_source=hci_source, controller_sink=hci_sink)
         return cls(config=config, host=host)
 
     @classmethod
-    def from_config_file_with_hci(cls, filename, hci_source, hci_sink):
+    def from_config_file_with_hci(
+        cls, filename: str, hci_source: TransportSource, hci_sink: TransportSink
+    ) -> Device:
         config = DeviceConfiguration()
         config.load_from_file(filename)
         return cls.from_config_with_hci(config, hci_source, hci_sink)
@@ -1096,7 +1126,7 @@ class Device(CompositeEventEmitter):
         return self._host
 
     @host.setter
-    def host(self, host):
+    def host(self, host: Host) -> None:
         # Unsubscribe from events from the current host
         if self._host:
             for event_name in device_host_event_handlers:
@@ -1156,8 +1186,8 @@ class Device(CompositeEventEmitter):
     def create_l2cap_registrar(self, psm):
         return lambda handler: self.register_l2cap_server(psm, handler)
 
-    def register_l2cap_server(self, psm, server):
-        self.l2cap_channel_manager.register_server(psm, server)
+    def register_l2cap_server(self, psm, server) -> int:
+        return self.l2cap_channel_manager.register_server(psm, server)
 
     def register_l2cap_channel_server(
         self,
@@ -1183,7 +1213,7 @@ class Device(CompositeEventEmitter):
             connection, psm, max_credits, mtu, mps
         )
 
-    def send_l2cap_pdu(self, connection_handle, cid, pdu):
+    def send_l2cap_pdu(self, connection_handle: int, cid: int, pdu: bytes) -> None:
         self.host.send_l2cap_pdu(connection_handle, cid, pdu)
 
     async def send_command(self, command, check_result=False):
@@ -2083,11 +2113,30 @@ class Device(CompositeEventEmitter):
         supervision_timeout,
         min_ce_length=0,
         max_ce_length=0,
-    ):
+        use_l2cap=False,
+    ) -> None:
         '''
         NOTE: the name of the parameters may look odd, but it just follows the names
         used in the Bluetooth spec.
         '''
+
+        if use_l2cap:
+            if connection.role != BT_PERIPHERAL_ROLE:
+                raise InvalidStateError(
+                    'only peripheral can update connection parameters with l2cap'
+                )
+            l2cap_result = (
+                await self.l2cap_channel_manager.update_connection_parameters(
+                    connection,
+                    connection_interval_min,
+                    connection_interval_max,
+                    max_latency,
+                    supervision_timeout,
+                )
+            )
+            if l2cap_result != l2cap.L2CAP_CONNECTION_PARAMETERS_ACCEPTED_RESULT:
+                raise ConnectionParameterUpdateError(l2cap_result)
+
         result = await self.send_command(
             HCI_LE_Connection_Update_Command(
                 connection_handle=connection.handle,
@@ -2097,7 +2146,7 @@ class Device(CompositeEventEmitter):
                 supervision_timeout=supervision_timeout,
                 min_ce_length=min_ce_length,
                 max_ce_length=max_ce_length,
-            )
+            )  # type: ignore[call-arg]
         )
         if result.status != HCI_Command_Status_Event.PENDING:
             raise HCI_StatusError(result)
@@ -2238,9 +2287,11 @@ class Device(CompositeEventEmitter):
     def request_pairing(self, connection):
         return self.smp_manager.request_pairing(connection)
 
-    async def get_long_term_key(self, connection_handle, rand, ediv):
+    async def get_long_term_key(
+        self, connection_handle: int, rand: bytes, ediv: int
+    ) -> Optional[bytes]:
         if (connection := self.lookup_connection(connection_handle)) is None:
-            return
+            return None
 
         # Start by looking for the key in an SMP session
         ltk = self.smp_manager.get_long_term_key(connection, rand, ediv)
@@ -2260,19 +2311,24 @@ class Device(CompositeEventEmitter):
 
                 if connection.role == BT_PERIPHERAL_ROLE and keys.ltk_peripheral:
                     return keys.ltk_peripheral.value
+        return None
 
     async def get_link_key(self, address: Address) -> Optional[bytes]:
+        if self.keystore is None:
+            return None
+
         # Look for the key in the keystore
-        if self.keystore is not None:
-            keys = await self.keystore.get(str(address))
-            if keys is not None:
-                logger.debug('found keys in the key store')
-                if keys.link_key is None:
-                    logger.warning('no link key')
-                    return None
+        keys = await self.keystore.get(str(address))
+        if keys is None:
+            logger.debug(f'no keys found for {address}')
+            return None
 
-                return keys.link_key.value
-        return None
+        logger.debug('found keys in the key store')
+        if keys.link_key is None:
+            logger.warning('no link key')
+            return None
+
+        return keys.link_key.value
 
     # [Classic only]
     async def authenticate(self, connection):
@@ -2391,6 +2447,18 @@ class Device(CompositeEventEmitter):
                 'connection_encryption_failure', on_encryption_failure
             )
 
+    async def update_keys(self, address: str, keys: PairingKeys) -> None:
+        if self.keystore is None:
+            return
+
+        try:
+            await self.keystore.update(address, keys)
+            await self.refresh_resolving_list()
+        except Exception as error:
+            logger.warning(f'!!! error while storing keys: {error}')
+        else:
+            self.emit('key_store_update')
+
     # [Classic only]
     async def switch_role(self, connection: Connection, role: int):
         pending_role_change = asyncio.get_running_loop().create_future()
@@ -2485,13 +2553,7 @@ class Device(CompositeEventEmitter):
                 value=link_key, authenticated=authenticated
             )
 
-            async def store_keys():
-                try:
-                    await self.keystore.update(str(bd_addr), pairing_keys)
-                except Exception as error:
-                    logger.warning(f'!!! error while storing keys: {error}')
-
-            self.abort_on('flush', store_keys())
+            self.abort_on('flush', self.update_keys(str(bd_addr), pairing_keys))
 
         if connection := self.find_connection_by_bd_addr(
             bd_addr, transport=BT_BR_EDR_TRANSPORT
@@ -2696,7 +2758,9 @@ class Device(CompositeEventEmitter):
             self.abort_on(
                 'flush',
                 self.start_advertising(
-                    advertising_type=self.advertising_type, auto_restart=True
+                    advertising_type=self.advertising_type,
+                    own_address_type=self.advertising_own_address_type,
+                    auto_restart=True,
                 ),
             )
 
@@ -2743,20 +2807,6 @@ class Device(CompositeEventEmitter):
         )
         connection.emit('connection_authentication_failure', error)
 
-    @host_event_handler
-    @with_connection_from_address
-    def on_ssp_complete(self, connection):
-        # On Secure Simple Pairing complete, in case:
-        # - Connection isn't already authenticated
-        # - AND we are not the initiator of the authentication
-        # We must trigger authentication to know if we are truly authenticated
-        if not connection.authenticating and not connection.authenticated:
-            logger.debug(
-                f'*** Trigger Connection Authentication: [0x{connection.handle:04X}] '
-                f'{connection.peer_address}'
-            )
-            asyncio.create_task(connection.authenticate())
-
     # [Classic only]
     @host_event_handler
     @with_connection_from_address
@@ -3111,6 +3161,18 @@ class Device(CompositeEventEmitter):
             connection.emit('role_change_failure', error)
         self.emit('role_change_failure', address, error)
 
+    # [Classic only]
+    @host_event_handler
+    @with_connection_from_address
+    def on_classic_pairing(self, connection: Connection) -> None:
+        connection.emit('classic_pairing')
+
+    # [Classic only]
+    @host_event_handler
+    @with_connection_from_address
+    def on_classic_pairing_failure(self, connection: Connection, status) -> None:
+        connection.emit('classic_pairing_failure', status)
+
     def on_pairing_start(self, connection: Connection) -> None:
         connection.emit('pairing_start')
 
@@ -3159,7 +3221,7 @@ class Device(CompositeEventEmitter):
 
     @host_event_handler
     @with_connection_from_handle
-    def on_l2cap_pdu(self, connection, cid, pdu):
+    def on_l2cap_pdu(self, connection: Connection, cid: int, pdu: bytes):
         self.l2cap_channel_manager.on_pdu(connection, cid, pdu)
 
     def __str__(self):
diff --git a/bumble/drivers/__init__.py b/bumble/drivers/__init__.py
index 2decab7..d8ea06e 100644
--- a/bumble/drivers/__init__.py
+++ b/bumble/drivers/__init__.py
@@ -21,6 +21,8 @@ like loading firmware after a cold start.
 # -----------------------------------------------------------------------------
 import abc
 import logging
+import pathlib
+import platform
 from . import rtk
 
 
@@ -66,3 +68,24 @@ async def get_driver_for_host(host):
         return driver
 
     return None
+
+
+def project_data_dir() -> pathlib.Path:
+    """
+    Returns:
+        A path to an OS-specific directory for bumble data. The directory is created if
+         it doesn't exist.
+    """
+    import platformdirs
+
+    if platform.system() == 'Darwin':
+        # platformdirs doesn't handle macOS right: it doesn't assemble a bundle id
+        # out of author & project
+        return platformdirs.user_data_path(
+            appname='com.google.bumble', ensure_exists=True
+        )
+    else:
+        # windows and linux don't use the com qualifier
+        return platformdirs.user_data_path(
+            appname='bumble', appauthor='google', ensure_exists=True
+        )
diff --git a/bumble/drivers/rtk.py b/bumble/drivers/rtk.py
index c0bccc9..f78a14d 100644
--- a/bumble/drivers/rtk.py
+++ b/bumble/drivers/rtk.py
@@ -34,10 +34,9 @@ import weakref
 
 
 from bumble.hci import (
-    hci_command_op_code,
+    hci_vendor_command_op_code,
     STATUS_SPEC,
     HCI_SUCCESS,
-    HCI_COMMAND_NAMES,
     HCI_Command,
     HCI_Reset_Command,
     HCI_Read_Local_Version_Information_Command,
@@ -125,6 +124,7 @@ RTK_USB_PRODUCTS = {
     (0x2550, 0x8761),
     (0x2B89, 0x8761),
     (0x7392, 0xC611),
+    (0x0BDA, 0x877B),
     # Realtek 8821AE
     (0x0B05, 0x17DC),
     (0x13D3, 0x3414),
@@ -178,8 +178,10 @@ RTK_USB_PRODUCTS = {
 # -----------------------------------------------------------------------------
 # HCI Commands
 # -----------------------------------------------------------------------------
-HCI_RTK_READ_ROM_VERSION_COMMAND = hci_command_op_code(0x3F, 0x6D)
-HCI_COMMAND_NAMES[HCI_RTK_READ_ROM_VERSION_COMMAND] = "HCI_RTK_READ_ROM_VERSION_COMMAND"
+HCI_RTK_READ_ROM_VERSION_COMMAND = hci_vendor_command_op_code(0x6D)
+HCI_RTK_DOWNLOAD_COMMAND = hci_vendor_command_op_code(0x20)
+HCI_RTK_DROP_FIRMWARE_COMMAND = hci_vendor_command_op_code(0x66)
+HCI_Command.register_commands(globals())
 
 
 @HCI_Command.command(return_parameters_fields=[("status", STATUS_SPEC), ("version", 1)])
@@ -187,10 +189,6 @@ class HCI_RTK_Read_ROM_Version_Command(HCI_Command):
     pass
 
 
-HCI_RTK_DOWNLOAD_COMMAND = hci_command_op_code(0x3F, 0x20)
-HCI_COMMAND_NAMES[HCI_RTK_DOWNLOAD_COMMAND] = "HCI_RTK_DOWNLOAD_COMMAND"
-
-
 @HCI_Command.command(
     fields=[("index", 1), ("payload", RTK_FRAGMENT_LENGTH)],
     return_parameters_fields=[("status", STATUS_SPEC), ("index", 1)],
@@ -199,10 +197,6 @@ class HCI_RTK_Download_Command(HCI_Command):
     pass
 
 
-HCI_RTK_DROP_FIRMWARE_COMMAND = hci_command_op_code(0x3F, 0x66)
-HCI_COMMAND_NAMES[HCI_RTK_DROP_FIRMWARE_COMMAND] = "HCI_RTK_DROP_FIRMWARE_COMMAND"
-
-
 @HCI_Command.command()
 class HCI_RTK_Drop_Firmware_Command(HCI_Command):
     pass
@@ -445,6 +439,11 @@ class Driver:
             # When the environment variable is set, don't look elsewhere
             return None
 
+        # Then, look where the firmware download tool writes by default
+        if (path := rtk_firmware_dir() / file_name).is_file():
+            logger.debug(f"{file_name} found in project data dir")
+            return path
+
         # Then, look in the package's driver directory
         if (path := pathlib.Path(__file__).parent / "rtk_fw" / file_name).is_file():
             logger.debug(f"{file_name} found in package dir")
@@ -645,3 +644,16 @@ class Driver:
         await self.download_firmware()
         await self.host.send_command(HCI_Reset_Command(), check_result=True)
         logger.info(f"loaded FW image {self.driver_info.fw_name}")
+
+
+def rtk_firmware_dir() -> pathlib.Path:
+    """
+    Returns:
+        A path to a subdir of the project data dir for Realtek firmware.
+         The directory is created if it doesn't exist.
+    """
+    from bumble.drivers import project_data_dir
+
+    p = project_data_dir() / "firmware" / "realtek"
+    p.mkdir(parents=True, exist_ok=True)
+    return p
diff --git a/bumble/gatt.py b/bumble/gatt.py
index 067f31d..fe3e85c 100644
--- a/bumble/gatt.py
+++ b/bumble/gatt.py
@@ -28,7 +28,7 @@ import enum
 import functools
 import logging
 import struct
-from typing import Optional, Sequence, List
+from typing import Optional, Sequence, Iterable, List, Union
 
 from .colors import color
 from .core import UUID, get_dict_key_by_value
@@ -187,7 +187,7 @@ GATT_CENTRAL_ADDRESS_RESOLUTION__CHARACTERISTIC                = UUID.from_16_bi
 # -----------------------------------------------------------------------------
 
 
-def show_services(services):
+def show_services(services: Iterable[Service]) -> None:
     for service in services:
         print(color(str(service), 'cyan'))
 
@@ -210,11 +210,11 @@ class Service(Attribute):
 
     def __init__(
         self,
-        uuid,
+        uuid: Union[str, UUID],
         characteristics: List[Characteristic],
         primary=True,
         included_services: List[Service] = [],
-    ):
+    ) -> None:
         # Convert the uuid to a UUID object if it isn't already
         if isinstance(uuid, str):
             uuid = UUID(uuid)
@@ -239,7 +239,7 @@ class Service(Attribute):
         """
         return None
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'Service(handle=0x{self.handle:04X}, '
             f'end=0x{self.end_group_handle:04X}, '
@@ -255,9 +255,11 @@ class TemplateService(Service):
     to expose their UUID as a class property
     '''
 
-    UUID: Optional[UUID] = None
+    UUID: UUID
 
-    def __init__(self, characteristics, primary=True):
+    def __init__(
+        self, characteristics: List[Characteristic], primary: bool = True
+    ) -> None:
         super().__init__(self.UUID, characteristics, primary)
 
 
@@ -269,7 +271,7 @@ class IncludedServiceDeclaration(Attribute):
 
     service: Service
 
-    def __init__(self, service):
+    def __init__(self, service: Service) -> None:
         declaration_bytes = struct.pack(
             '<HH2s', service.handle, service.end_group_handle, service.uuid.to_bytes()
         )
@@ -278,7 +280,7 @@ class IncludedServiceDeclaration(Attribute):
         )
         self.service = service
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'IncludedServiceDefinition(handle=0x{self.handle:04X}, '
             f'group_starting_handle=0x{self.service.handle:04X}, '
@@ -326,7 +328,7 @@ class Characteristic(Attribute):
                     f"Characteristic.Properties::from_string() error:\nExpected a string containing any of the keys, separated by , or |: {enum_list_str}\nGot: {properties_str}"
                 )
 
-        def __str__(self):
+        def __str__(self) -> str:
             # NOTE: we override this method to offer a consistent result between python
             # versions: the value returned by IntFlag.__str__() changed in version 11.
             return '|'.join(
@@ -348,10 +350,10 @@ class Characteristic(Attribute):
 
     def __init__(
         self,
-        uuid,
+        uuid: Union[str, bytes, UUID],
         properties: Characteristic.Properties,
-        permissions,
-        value=b'',
+        permissions: Union[str, Attribute.Permissions],
+        value: Union[str, bytes, CharacteristicValue] = b'',
         descriptors: Sequence[Descriptor] = (),
     ):
         super().__init__(uuid, permissions, value)
@@ -369,7 +371,7 @@ class Characteristic(Attribute):
     def has_properties(self, properties: Characteristic.Properties) -> bool:
         return self.properties & properties == properties
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'Characteristic(handle=0x{self.handle:04X}, '
             f'end=0x{self.end_group_handle:04X}, '
@@ -386,7 +388,7 @@ class CharacteristicDeclaration(Attribute):
 
     characteristic: Characteristic
 
-    def __init__(self, characteristic, value_handle):
+    def __init__(self, characteristic: Characteristic, value_handle: int) -> None:
         declaration_bytes = (
             struct.pack('<BH', characteristic.properties, value_handle)
             + characteristic.uuid.to_pdu_bytes()
@@ -397,7 +399,7 @@ class CharacteristicDeclaration(Attribute):
         self.value_handle = value_handle
         self.characteristic = characteristic
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'CharacteristicDeclaration(handle=0x{self.handle:04X}, '
             f'value_handle=0x{self.value_handle:04X}, '
@@ -520,7 +522,7 @@ class CharacteristicAdapter:
 
         return self.wrapped_characteristic.unsubscribe(subscriber)
 
-    def __str__(self):
+    def __str__(self) -> str:
         wrapped = str(self.wrapped_characteristic)
         return f'{self.__class__.__name__}({wrapped})'
 
@@ -600,10 +602,10 @@ class UTF8CharacteristicAdapter(CharacteristicAdapter):
     Adapter that converts strings to/from bytes using UTF-8 encoding
     '''
 
-    def encode_value(self, value):
+    def encode_value(self, value: str) -> bytes:
         return value.encode('utf-8')
 
-    def decode_value(self, value):
+    def decode_value(self, value: bytes) -> str:
         return value.decode('utf-8')
 
 
@@ -613,7 +615,7 @@ class Descriptor(Attribute):
     See Vol 3, Part G - 3.3.3 Characteristic Descriptor Declarations
     '''
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'Descriptor(handle=0x{self.handle:04X}, '
             f'type={self.type}, '
diff --git a/bumble/gatt_client.py b/bumble/gatt_client.py
index a33039e..e3b8bb2 100644
--- a/bumble/gatt_client.py
+++ b/bumble/gatt_client.py
@@ -28,7 +28,18 @@ import asyncio
 import logging
 import struct
 from datetime import datetime
-from typing import List, Optional, Dict, Tuple, Callable, Union, Any
+from typing import (
+    List,
+    Optional,
+    Dict,
+    Tuple,
+    Callable,
+    Union,
+    Any,
+    Iterable,
+    Type,
+    TYPE_CHECKING,
+)
 
 from pyee import EventEmitter
 
@@ -66,8 +77,12 @@ from .gatt import (
     GATT_INCLUDE_ATTRIBUTE_TYPE,
     Characteristic,
     ClientCharacteristicConfigurationBits,
+    TemplateService,
 )
 
+if TYPE_CHECKING:
+    from bumble.device import Connection
+
 # -----------------------------------------------------------------------------
 # Logging
 # -----------------------------------------------------------------------------
@@ -78,16 +93,16 @@ logger = logging.getLogger(__name__)
 # Proxies
 # -----------------------------------------------------------------------------
 class AttributeProxy(EventEmitter):
-    client: Client
-
-    def __init__(self, client, handle, end_group_handle, attribute_type):
+    def __init__(
+        self, client: Client, handle: int, end_group_handle: int, attribute_type: UUID
+    ) -> None:
         EventEmitter.__init__(self)
         self.client = client
         self.handle = handle
         self.end_group_handle = end_group_handle
         self.type = attribute_type
 
-    async def read_value(self, no_long_read=False):
+    async def read_value(self, no_long_read: bool = False) -> bytes:
         return self.decode_value(
             await self.client.read_value(self.handle, no_long_read)
         )
@@ -97,13 +112,13 @@ class AttributeProxy(EventEmitter):
             self.handle, self.encode_value(value), with_response
         )
 
-    def encode_value(self, value):
+    def encode_value(self, value: Any) -> bytes:
         return value
 
-    def decode_value(self, value_bytes):
+    def decode_value(self, value_bytes: bytes) -> Any:
         return value_bytes
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f'Attribute(handle=0x{self.handle:04X}, type={self.type})'
 
 
@@ -136,14 +151,14 @@ class ServiceProxy(AttributeProxy):
     def get_characteristics_by_uuid(self, uuid):
         return self.client.get_characteristics_by_uuid(uuid, self)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f'Service(handle=0x{self.handle:04X}, uuid={self.uuid})'
 
 
 class CharacteristicProxy(AttributeProxy):
     properties: Characteristic.Properties
     descriptors: List[DescriptorProxy]
-    subscribers: Dict[Any, Callable]
+    subscribers: Dict[Any, Callable[[bytes], Any]]
 
     def __init__(
         self,
@@ -171,7 +186,9 @@ class CharacteristicProxy(AttributeProxy):
         return await self.client.discover_descriptors(self)
 
     async def subscribe(
-        self, subscriber: Optional[Callable] = None, prefer_notify=True
+        self,
+        subscriber: Optional[Callable[[bytes], Any]] = None,
+        prefer_notify: bool = True,
     ):
         if subscriber is not None:
             if subscriber in self.subscribers:
@@ -195,7 +212,7 @@ class CharacteristicProxy(AttributeProxy):
 
         return await self.client.unsubscribe(self, subscriber)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'Characteristic(handle=0x{self.handle:04X}, '
             f'uuid={self.uuid}, '
@@ -207,7 +224,7 @@ class DescriptorProxy(AttributeProxy):
     def __init__(self, client, handle, descriptor_type):
         super().__init__(client, handle, 0, descriptor_type)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f'Descriptor(handle=0x{self.handle:04X}, type={self.type})'
 
 
@@ -216,8 +233,10 @@ class ProfileServiceProxy:
     Base class for profile-specific service proxies
     '''
 
+    SERVICE_CLASS: Type[TemplateService]
+
     @classmethod
-    def from_client(cls, client):
+    def from_client(cls, client: Client) -> ProfileServiceProxy:
         return ServiceProxy.from_client(cls, client, cls.SERVICE_CLASS.UUID)
 
 
@@ -227,8 +246,12 @@ class ProfileServiceProxy:
 class Client:
     services: List[ServiceProxy]
     cached_values: Dict[int, Tuple[datetime, bytes]]
+    notification_subscribers: Dict[int, Callable[[bytes], Any]]
+    indication_subscribers: Dict[int, Callable[[bytes], Any]]
+    pending_response: Optional[asyncio.futures.Future[ATT_PDU]]
+    pending_request: Optional[ATT_PDU]
 
-    def __init__(self, connection):
+    def __init__(self, connection: Connection) -> None:
         self.connection = connection
         self.mtu_exchange_done = False
         self.request_semaphore = asyncio.Semaphore(1)
@@ -241,16 +264,16 @@ class Client:
         self.services = []
         self.cached_values = {}
 
-    def send_gatt_pdu(self, pdu):
+    def send_gatt_pdu(self, pdu: bytes) -> None:
         self.connection.send_l2cap_pdu(ATT_CID, pdu)
 
-    async def send_command(self, command):
+    async def send_command(self, command: ATT_PDU) -> None:
         logger.debug(
             f'GATT Command from client: [0x{self.connection.handle:04X}] {command}'
         )
         self.send_gatt_pdu(command.to_bytes())
 
-    async def send_request(self, request):
+    async def send_request(self, request: ATT_PDU):
         logger.debug(
             f'GATT Request from client: [0x{self.connection.handle:04X}] {request}'
         )
@@ -279,14 +302,14 @@ class Client:
 
         return response
 
-    def send_confirmation(self, confirmation):
+    def send_confirmation(self, confirmation: ATT_Handle_Value_Confirmation) -> None:
         logger.debug(
             f'GATT Confirmation from client: [0x{self.connection.handle:04X}] '
             f'{confirmation}'
         )
         self.send_gatt_pdu(confirmation.to_bytes())
 
-    async def request_mtu(self, mtu):
+    async def request_mtu(self, mtu: int) -> int:
         # Check the range
         if mtu < ATT_DEFAULT_MTU:
             raise ValueError(f'MTU must be >= {ATT_DEFAULT_MTU}')
@@ -313,10 +336,12 @@ class Client:
 
         return self.connection.att_mtu
 
-    def get_services_by_uuid(self, uuid):
+    def get_services_by_uuid(self, uuid: UUID) -> List[ServiceProxy]:
         return [service for service in self.services if service.uuid == uuid]
 
-    def get_characteristics_by_uuid(self, uuid, service=None):
+    def get_characteristics_by_uuid(
+        self, uuid: UUID, service: Optional[ServiceProxy] = None
+    ) -> List[CharacteristicProxy]:
         services = [service] if service else self.services
         return [
             c
@@ -363,7 +388,7 @@ class Client:
         if not already_known:
             self.services.append(service)
 
-    async def discover_services(self, uuids=None) -> List[ServiceProxy]:
+    async def discover_services(self, uuids: Iterable[UUID] = []) -> List[ServiceProxy]:
         '''
         See Vol 3, Part G - 4.4.1 Discover All Primary Services
         '''
@@ -435,7 +460,7 @@ class Client:
 
         return services
 
-    async def discover_service(self, uuid):
+    async def discover_service(self, uuid: Union[str, UUID]) -> List[ServiceProxy]:
         '''
         See Vol 3, Part G - 4.4.2 Discover Primary Service by Service UUID
         '''
@@ -468,7 +493,7 @@ class Client:
                         f'{HCI_Constant.error_name(response.error_code)}'
                     )
                     # TODO raise appropriate exception
-                    return
+                    return []
                 break
 
             for attribute_handle, end_group_handle in response.handles_information:
@@ -480,7 +505,7 @@ class Client:
                     logger.warning(
                         f'bogus handle values: {attribute_handle} {end_group_handle}'
                     )
-                    return
+                    return []
 
                 # Create a service proxy for this service
                 service = ServiceProxy(
@@ -721,7 +746,7 @@ class Client:
 
         return descriptors
 
-    async def discover_attributes(self):
+    async def discover_attributes(self) -> List[AttributeProxy]:
         '''
         Discover all attributes, regardless of type
         '''
@@ -844,7 +869,9 @@ class Client:
             # No more subscribers left
             await self.write_value(cccd, b'\x00\x00', with_response=True)
 
-    async def read_value(self, attribute, no_long_read=False):
+    async def read_value(
+        self, attribute: Union[int, AttributeProxy], no_long_read: bool = False
+    ) -> Any:
         '''
         See Vol 3, Part G - 4.8.1 Read Characteristic Value
 
@@ -905,7 +932,9 @@ class Client:
         # Return the value as bytes
         return attribute_value
 
-    async def read_characteristics_by_uuid(self, uuid, service):
+    async def read_characteristics_by_uuid(
+        self, uuid: UUID, service: Optional[ServiceProxy]
+    ) -> List[bytes]:
         '''
         See Vol 3, Part G - 4.8.2 Read Using Characteristic UUID
         '''
@@ -960,7 +989,12 @@ class Client:
 
         return characteristics_values
 
-    async def write_value(self, attribute, value, with_response=False):
+    async def write_value(
+        self,
+        attribute: Union[int, AttributeProxy],
+        value: bytes,
+        with_response: bool = False,
+    ) -> None:
         '''
         See Vol 3, Part G - 4.9.1 Write Without Response & 4.9.3 Write Characteristic
         Value
@@ -990,7 +1024,7 @@ class Client:
                 )
             )
 
-    def on_gatt_pdu(self, att_pdu):
+    def on_gatt_pdu(self, att_pdu: ATT_PDU) -> None:
         logger.debug(
             f'GATT Response to client: [0x{self.connection.handle:04X}] {att_pdu}'
         )
@@ -1013,6 +1047,7 @@ class Client:
                     return
 
             # Return the response to the coroutine that is waiting for it
+            assert self.pending_response is not None
             self.pending_response.set_result(att_pdu)
         else:
             handler_name = f'on_{att_pdu.name.lower()}'
@@ -1060,7 +1095,7 @@ class Client:
         # Confirm that we received the indication
         self.send_confirmation(ATT_Handle_Value_Confirmation())
 
-    def cache_value(self, attribute_handle: int, value: bytes):
+    def cache_value(self, attribute_handle: int, value: bytes) -> None:
         self.cached_values[attribute_handle] = (
             datetime.now(),
             value,
diff --git a/bumble/gatt_server.py b/bumble/gatt_server.py
index 3624905..cdf1b5e 100644
--- a/bumble/gatt_server.py
+++ b/bumble/gatt_server.py
@@ -23,11 +23,12 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
 import asyncio
 import logging
 from collections import defaultdict
 import struct
-from typing import List, Tuple, Optional, TypeVar, Type
+from typing import List, Tuple, Optional, TypeVar, Type, Dict, Iterable, TYPE_CHECKING
 from pyee import EventEmitter
 
 from .colors import color
@@ -42,6 +43,7 @@ from .att import (
     ATT_INVALID_OFFSET_ERROR,
     ATT_REQUEST_NOT_SUPPORTED_ERROR,
     ATT_REQUESTS,
+    ATT_PDU,
     ATT_UNLIKELY_ERROR_ERROR,
     ATT_UNSUPPORTED_GROUP_TYPE_ERROR,
     ATT_Error,
@@ -73,6 +75,8 @@ from .gatt import (
     Service,
 )
 
+if TYPE_CHECKING:
+    from bumble.device import Device, Connection
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -91,8 +95,13 @@ GATT_SERVER_DEFAULT_MAX_MTU = 517
 # -----------------------------------------------------------------------------
 class Server(EventEmitter):
     attributes: List[Attribute]
+    services: List[Service]
+    attributes_by_handle: Dict[int, Attribute]
+    subscribers: Dict[int, Dict[int, bytes]]
+    indication_semaphores: defaultdict[int, asyncio.Semaphore]
+    pending_confirmations: defaultdict[int, Optional[asyncio.futures.Future]]
 
-    def __init__(self, device):
+    def __init__(self, device: Device) -> None:
         super().__init__()
         self.device = device
         self.services = []
@@ -107,16 +116,16 @@ class Server(EventEmitter):
         self.indication_semaphores = defaultdict(lambda: asyncio.Semaphore(1))
         self.pending_confirmations = defaultdict(lambda: None)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "\n".join(map(str, self.attributes))
 
-    def send_gatt_pdu(self, connection_handle, pdu):
+    def send_gatt_pdu(self, connection_handle: int, pdu: bytes) -> None:
         self.device.send_l2cap_pdu(connection_handle, ATT_CID, pdu)
 
-    def next_handle(self):
+    def next_handle(self) -> int:
         return 1 + len(self.attributes)
 
-    def get_advertising_service_data(self):
+    def get_advertising_service_data(self) -> Dict[Attribute, bytes]:
         return {
             attribute: data
             for attribute in self.attributes
@@ -124,7 +133,7 @@ class Server(EventEmitter):
             and (data := attribute.get_advertising_data())
         }
 
-    def get_attribute(self, handle):
+    def get_attribute(self, handle: int) -> Optional[Attribute]:
         attribute = self.attributes_by_handle.get(handle)
         if attribute:
             return attribute
@@ -173,12 +182,17 @@ class Server(EventEmitter):
 
         return next(
             (
-                (attribute, self.get_attribute(attribute.characteristic.handle))
+                (
+                    attribute,
+                    self.get_attribute(attribute.characteristic.handle),
+                )  # type: ignore
                 for attribute in map(
                     self.get_attribute,
                     range(service_handle.handle, service_handle.end_group_handle + 1),
                 )
-                if attribute.type == GATT_CHARACTERISTIC_ATTRIBUTE_TYPE
+                if attribute is not None
+                and attribute.type == GATT_CHARACTERISTIC_ATTRIBUTE_TYPE
+                and isinstance(attribute, CharacteristicDeclaration)
                 and attribute.characteristic.uuid == characteristic_uuid
             ),
             None,
@@ -197,7 +211,7 @@ class Server(EventEmitter):
 
         return next(
             (
-                attribute
+                attribute  # type: ignore
                 for attribute in map(
                     self.get_attribute,
                     range(
@@ -205,12 +219,12 @@ class Server(EventEmitter):
                         characteristic_value.end_group_handle + 1,
                     ),
                 )
-                if attribute.type == descriptor_uuid
+                if attribute is not None and attribute.type == descriptor_uuid
             ),
             None,
         )
 
-    def add_attribute(self, attribute):
+    def add_attribute(self, attribute: Attribute) -> None:
         # Assign a handle to this attribute
         attribute.handle = self.next_handle()
         attribute.end_group_handle = (
@@ -220,7 +234,7 @@ class Server(EventEmitter):
         # Add this attribute to the list
         self.attributes.append(attribute)
 
-    def add_service(self, service: Service):
+    def add_service(self, service: Service) -> None:
         # Add the service attribute to the DB
         self.add_attribute(service)
 
@@ -285,11 +299,13 @@ class Server(EventEmitter):
         service.end_group_handle = self.attributes[-1].handle
         self.services.append(service)
 
-    def add_services(self, services):
+    def add_services(self, services: Iterable[Service]) -> None:
         for service in services:
             self.add_service(service)
 
-    def read_cccd(self, connection, characteristic):
+    def read_cccd(
+        self, connection: Optional[Connection], characteristic: Characteristic
+    ) -> bytes:
         if connection is None:
             return bytes([0, 0])
 
@@ -300,7 +316,12 @@ class Server(EventEmitter):
 
         return cccd or bytes([0, 0])
 
-    def write_cccd(self, connection, characteristic, value):
+    def write_cccd(
+        self,
+        connection: Connection,
+        characteristic: Characteristic,
+        value: bytes,
+    ) -> None:
         logger.debug(
             f'Subscription update for connection=0x{connection.handle:04X}, '
             f'handle=0x{characteristic.handle:04X}: {value.hex()}'
@@ -327,13 +348,19 @@ class Server(EventEmitter):
             indicate_enabled,
         )
 
-    def send_response(self, connection, response):
+    def send_response(self, connection: Connection, response: ATT_PDU) -> None:
         logger.debug(
             f'GATT Response from server: [0x{connection.handle:04X}] {response}'
         )
         self.send_gatt_pdu(connection.handle, response.to_bytes())
 
-    async def notify_subscriber(self, connection, attribute, value=None, force=False):
+    async def notify_subscriber(
+        self,
+        connection: Connection,
+        attribute: Attribute,
+        value: Optional[bytes] = None,
+        force: bool = False,
+    ) -> None:
         # Check if there's a subscriber
         if not force:
             subscribers = self.subscribers.get(connection.handle)
@@ -370,7 +397,13 @@ class Server(EventEmitter):
         )
         self.send_gatt_pdu(connection.handle, bytes(notification))
 
-    async def indicate_subscriber(self, connection, attribute, value=None, force=False):
+    async def indicate_subscriber(
+        self,
+        connection: Connection,
+        attribute: Attribute,
+        value: Optional[bytes] = None,
+        force: bool = False,
+    ) -> None:
         # Check if there's a subscriber
         if not force:
             subscribers = self.subscribers.get(connection.handle)
@@ -411,15 +444,13 @@ class Server(EventEmitter):
             assert self.pending_confirmations[connection.handle] is None
 
             # Create a future value to hold the eventual response
-            self.pending_confirmations[
+            pending_confirmation = self.pending_confirmations[
                 connection.handle
             ] = asyncio.get_running_loop().create_future()
 
             try:
                 self.send_gatt_pdu(connection.handle, indication.to_bytes())
-                await asyncio.wait_for(
-                    self.pending_confirmations[connection.handle], GATT_REQUEST_TIMEOUT
-                )
+                await asyncio.wait_for(pending_confirmation, GATT_REQUEST_TIMEOUT)
             except asyncio.TimeoutError as error:
                 logger.warning(color('!!! GATT Indicate timeout', 'red'))
                 raise TimeoutError(f'GATT timeout for {indication.name}') from error
@@ -427,8 +458,12 @@ class Server(EventEmitter):
                 self.pending_confirmations[connection.handle] = None
 
     async def notify_or_indicate_subscribers(
-        self, indicate, attribute, value=None, force=False
-    ):
+        self,
+        indicate: bool,
+        attribute: Attribute,
+        value: Optional[bytes] = None,
+        force: bool = False,
+    ) -> None:
         # Get all the connections for which there's at least one subscription
         connections = [
             connection
@@ -450,13 +485,23 @@ class Server(EventEmitter):
                 ]
             )
 
-    async def notify_subscribers(self, attribute, value=None, force=False):
+    async def notify_subscribers(
+        self,
+        attribute: Attribute,
+        value: Optional[bytes] = None,
+        force: bool = False,
+    ):
         return await self.notify_or_indicate_subscribers(False, attribute, value, force)
 
-    async def indicate_subscribers(self, attribute, value=None, force=False):
+    async def indicate_subscribers(
+        self,
+        attribute: Attribute,
+        value: Optional[bytes] = None,
+        force: bool = False,
+    ):
         return await self.notify_or_indicate_subscribers(True, attribute, value, force)
 
-    def on_disconnection(self, connection):
+    def on_disconnection(self, connection: Connection) -> None:
         if connection.handle in self.subscribers:
             del self.subscribers[connection.handle]
         if connection.handle in self.indication_semaphores:
@@ -464,7 +509,7 @@ class Server(EventEmitter):
         if connection.handle in self.pending_confirmations:
             del self.pending_confirmations[connection.handle]
 
-    def on_gatt_pdu(self, connection, att_pdu):
+    def on_gatt_pdu(self, connection: Connection, att_pdu: ATT_PDU) -> None:
         logger.debug(f'GATT Request to server: [0x{connection.handle:04X}] {att_pdu}')
         handler_name = f'on_{att_pdu.name.lower()}'
         handler = getattr(self, handler_name, None)
@@ -506,7 +551,7 @@ class Server(EventEmitter):
     #######################################################
     # ATT handlers
     #######################################################
-    def on_att_request(self, connection, pdu):
+    def on_att_request(self, connection: Connection, pdu: ATT_PDU) -> None:
         '''
         Handler for requests without a more specific handler
         '''
@@ -679,7 +724,6 @@ class Server(EventEmitter):
             and attribute.handle <= request.ending_handle
             and pdu_space_available
         ):
-
             try:
                 attribute_value = attribute.read_value(connection)
             except ATT_Error as error:
diff --git a/bumble/hci.py b/bumble/hci.py
index 0dbb127..41deed2 100644
--- a/bumble/hci.py
+++ b/bumble/hci.py
@@ -16,11 +16,11 @@
 # Imports
 # -----------------------------------------------------------------------------
 from __future__ import annotations
-import struct
 import collections
-import logging
 import functools
-from typing import Dict, Type, Union
+import logging
+import struct
+from typing import Any, Dict, Callable, Optional, Type, Union
 
 from .colors import color
 from .core import (
@@ -47,6 +47,10 @@ def hci_command_op_code(ogf, ocf):
     return ogf << 10 | ocf
 
 
+def hci_vendor_command_op_code(ocf):
+    return hci_command_op_code(HCI_VENDOR_OGF, ocf)
+
+
 def key_with_value(dictionary, target_value):
     for key, value in dictionary.items():
         if value == target_value:
@@ -101,6 +105,8 @@ def phy_list_to_bits(phys):
 # fmt: off
 # pylint: disable=line-too-long
 
+HCI_VENDOR_OGF = 0x3F
+
 # HCI Version
 HCI_VERSION_BLUETOOTH_CORE_1_0B    = 0
 HCI_VERSION_BLUETOOTH_CORE_1_1     = 1
@@ -206,10 +212,8 @@ HCI_INQUIRY_RESPONSE_NOTIFICATION_EVENT                          = 0X56
 HCI_AUTHENTICATED_PAYLOAD_TIMEOUT_EXPIRED_EVENT                  = 0X57
 HCI_SAM_STATUS_CHANGE_EVENT                                      = 0X58
 
-HCI_EVENT_NAMES = {
-    event_code: event_name for (event_name, event_code) in globals().items()
-    if event_name.startswith('HCI_') and event_name.endswith('_EVENT')
-}
+HCI_VENDOR_EVENT = 0xFF
+
 
 # HCI Subevent Codes
 HCI_LE_CONNECTION_COMPLETE_EVENT                         = 0x01
@@ -248,10 +252,6 @@ HCI_LE_TRANSMIT_POWER_REPORTING_EVENT                    = 0X21
 HCI_LE_BIGINFO_ADVERTISING_REPORT_EVENT                  = 0X22
 HCI_LE_SUBRATE_CHANGE_EVENT                              = 0X23
 
-HCI_SUBEVENT_NAMES = {
-    event_code: event_name for (event_name, event_code) in globals().items()
-    if event_name.startswith('HCI_LE_') and event_name.endswith('_EVENT') and event_code != HCI_LE_META_EVENT
-}
 
 # HCI Command
 HCI_INQUIRY_COMMAND                                                      = hci_command_op_code(0x01, 0x0001)
@@ -557,10 +557,6 @@ HCI_LE_SET_DATA_RELATED_ADDRESS_CHANGES_COMMAND                          = hci_c
 HCI_LE_SET_DEFAULT_SUBRATE_COMMAND                                       = hci_command_op_code(0x08, 0x007D)
 HCI_LE_SUBRATE_REQUEST_COMMAND                                           = hci_command_op_code(0x08, 0x007E)
 
-HCI_COMMAND_NAMES = {
-    command_code: command_name for (command_name, command_code) in globals().items()
-    if command_name.startswith('HCI_') and command_name.endswith('_COMMAND')
-}
 
 # HCI Error Codes
 # See Bluetooth spec Vol 2, Part D - 1.3 LIST OF ERROR CODES
@@ -1918,7 +1914,7 @@ class HCI_Packet:
     hci_packet_type: int
 
     @staticmethod
-    def from_bytes(packet):
+    def from_bytes(packet: bytes) -> HCI_Packet:
         packet_type = packet[0]
 
         if packet_type == HCI_COMMAND_PACKET:
@@ -1960,6 +1956,7 @@ class HCI_Command(HCI_Packet):
     '''
 
     hci_packet_type = HCI_COMMAND_PACKET
+    command_names: Dict[int, str] = {}
     command_classes: Dict[int, Type[HCI_Command]] = {}
 
     @staticmethod
@@ -1970,9 +1967,9 @@ class HCI_Command(HCI_Packet):
 
         def inner(cls):
             cls.name = cls.__name__.upper()
-            cls.op_code = key_with_value(HCI_COMMAND_NAMES, cls.name)
+            cls.op_code = key_with_value(cls.command_names, cls.name)
             if cls.op_code is None:
-                raise KeyError(f'command {cls.name} not found in HCI_COMMAND_NAMES')
+                raise KeyError(f'command {cls.name} not found in command_names')
             cls.fields = fields
             cls.return_parameters_fields = return_parameters_fields
 
@@ -1992,7 +1989,19 @@ class HCI_Command(HCI_Packet):
         return inner
 
     @staticmethod
-    def from_bytes(packet):
+    def command_map(symbols: Dict[str, Any]) -> Dict[int, str]:
+        return {
+            command_code: command_name
+            for (command_name, command_code) in symbols.items()
+            if command_name.startswith('HCI_') and command_name.endswith('_COMMAND')
+        }
+
+    @classmethod
+    def register_commands(cls, symbols: Dict[str, Any]) -> None:
+        cls.command_names.update(cls.command_map(symbols))
+
+    @staticmethod
+    def from_bytes(packet: bytes) -> HCI_Command:
         op_code, length = struct.unpack_from('<HB', packet, 1)
         parameters = packet[4:]
         if len(parameters) != length:
@@ -2011,11 +2020,11 @@ class HCI_Command(HCI_Packet):
             HCI_Object.init_from_bytes(self, parameters, 0, fields)
             return self
 
-        return cls.from_parameters(parameters)
+        return cls.from_parameters(parameters)  # type: ignore
 
     @staticmethod
     def command_name(op_code):
-        name = HCI_COMMAND_NAMES.get(op_code)
+        name = HCI_Command.command_names.get(op_code)
         if name is not None:
             return name
         return f'[OGF=0x{op_code >> 10:02x}, OCF=0x{op_code & 0x3FF:04x}]'
@@ -2024,6 +2033,16 @@ class HCI_Command(HCI_Packet):
     def create_return_parameters(cls, **kwargs):
         return HCI_Object(cls.return_parameters_fields, **kwargs)
 
+    @classmethod
+    def parse_return_parameters(cls, parameters):
+        if not cls.return_parameters_fields:
+            return None
+        return_parameters = HCI_Object.from_bytes(
+            parameters, 0, cls.return_parameters_fields
+        )
+        return_parameters.fields = cls.return_parameters_fields
+        return return_parameters
+
     def __init__(self, op_code, parameters=None, **kwargs):
         super().__init__(HCI_Command.command_name(op_code))
         if (fields := getattr(self, 'fields', None)) and kwargs:
@@ -2053,6 +2072,9 @@ class HCI_Command(HCI_Packet):
         return result
 
 
+HCI_Command.register_commands(globals())
+
+
 # -----------------------------------------------------------------------------
 @HCI_Command.command(
     [
@@ -4308,8 +4330,8 @@ class HCI_Event(HCI_Packet):
     '''
 
     hci_packet_type = HCI_EVENT_PACKET
+    event_names: Dict[int, str] = {}
     event_classes: Dict[int, Type[HCI_Event]] = {}
-    meta_event_classes: Dict[int, Type[HCI_LE_Meta_Event]] = {}
 
     @staticmethod
     def event(fields=()):
@@ -4319,9 +4341,9 @@ class HCI_Event(HCI_Packet):
 
         def inner(cls):
             cls.name = cls.__name__.upper()
-            cls.event_code = key_with_value(HCI_EVENT_NAMES, cls.name)
+            cls.event_code = key_with_value(cls.event_names, cls.name)
             if cls.event_code is None:
-                raise KeyError('event not found in HCI_EVENT_NAMES')
+                raise KeyError(f'event {cls.name} not found in event_names')
             cls.fields = fields
 
             # Patch the __init__ method to fix the event_code
@@ -4338,11 +4360,29 @@ class HCI_Event(HCI_Packet):
         return inner
 
     @staticmethod
+    def event_map(symbols: Dict[str, Any]) -> Dict[int, str]:
+        return {
+            event_code: event_name
+            for (event_name, event_code) in symbols.items()
+            if event_name.startswith('HCI_')
+            and not event_name.startswith('HCI_LE_')
+            and event_name.endswith('_EVENT')
+        }
+
+    @staticmethod
+    def event_name(event_code):
+        return name_or_number(HCI_Event.event_names, event_code)
+
+    @staticmethod
+    def register_events(symbols: Dict[str, Any]) -> None:
+        HCI_Event.event_names.update(HCI_Event.event_map(symbols))
+
+    @staticmethod
     def registered(event_class):
         event_class.name = event_class.__name__.upper()
-        event_class.event_code = key_with_value(HCI_EVENT_NAMES, event_class.name)
+        event_class.event_code = key_with_value(HCI_Event.event_names, event_class.name)
         if event_class.event_code is None:
-            raise KeyError('event not found in HCI_EVENT_NAMES')
+            raise KeyError(f'event {event_class.name} not found in event_names')
 
         # Register a factory for this class
         HCI_Event.event_classes[event_class.event_code] = event_class
@@ -4350,22 +4390,28 @@ class HCI_Event(HCI_Packet):
         return event_class
 
     @staticmethod
-    def from_bytes(packet):
+    def from_bytes(packet: bytes) -> HCI_Event:
         event_code = packet[1]
         length = packet[2]
         parameters = packet[3:]
         if len(parameters) != length:
             raise ValueError('invalid packet length')
 
+        cls: Any
         if event_code == HCI_LE_META_EVENT:
             # We do this dispatch here and not in the subclass in order to avoid call
             # loops
             subevent_code = parameters[0]
-            cls = HCI_Event.meta_event_classes.get(subevent_code)
+            cls = HCI_LE_Meta_Event.subevent_classes.get(subevent_code)
             if cls is None:
                 # No class registered, just use a generic class instance
                 return HCI_LE_Meta_Event(subevent_code, parameters)
-
+        elif event_code == HCI_VENDOR_EVENT:
+            subevent_code = parameters[0]
+            cls = HCI_Vendor_Event.subevent_classes.get(subevent_code)
+            if cls is None:
+                # No class registered, just use a generic class instance
+                return HCI_Vendor_Event(subevent_code, parameters)
         else:
             cls = HCI_Event.event_classes.get(event_code)
             if cls is None:
@@ -4373,7 +4419,7 @@ class HCI_Event(HCI_Packet):
                 return HCI_Event(event_code, parameters)
 
         # Invoke the factory to create a new instance
-        return cls.from_parameters(parameters)
+        return cls.from_parameters(parameters)  # type: ignore
 
     @classmethod
     def from_parameters(cls, parameters):
@@ -4383,10 +4429,6 @@ class HCI_Event(HCI_Packet):
             HCI_Object.init_from_bytes(self, parameters, 0, fields)
         return self
 
-    @staticmethod
-    def event_name(event_code):
-        return name_or_number(HCI_EVENT_NAMES, event_code)
-
     def __init__(self, event_code, parameters=None, **kwargs):
         super().__init__(HCI_Event.event_name(event_code))
         if (fields := getattr(self, 'fields', None)) and kwargs:
@@ -4413,71 +4455,111 @@ class HCI_Event(HCI_Packet):
         return result
 
 
+HCI_Event.register_events(globals())
+
+
 # -----------------------------------------------------------------------------
-class HCI_LE_Meta_Event(HCI_Event):
+class HCI_Extended_Event(HCI_Event):
     '''
-    See Bluetooth spec @ 7.7.65 LE Meta Event
+    HCI_Event subclass for events that has a subevent code.
     '''
 
-    @staticmethod
-    def event(fields=()):
+    subevent_names: Dict[int, str] = {}
+    subevent_classes: Dict[int, Type[HCI_Extended_Event]]
+
+    @classmethod
+    def event(cls, fields=()):
         '''
         Decorator used to declare and register subclasses
         '''
 
         def inner(cls):
             cls.name = cls.__name__.upper()
-            cls.subevent_code = key_with_value(HCI_SUBEVENT_NAMES, cls.name)
+            cls.subevent_code = key_with_value(cls.subevent_names, cls.name)
             if cls.subevent_code is None:
-                raise KeyError('subevent not found in HCI_SUBEVENT_NAMES')
+                raise KeyError(f'subevent {cls.name} not found in subevent_names')
             cls.fields = fields
 
             # Patch the __init__ method to fix the subevent_code
+            original_init = cls.__init__
+
             def init(self, parameters=None, **kwargs):
-                return HCI_LE_Meta_Event.__init__(
-                    self, cls.subevent_code, parameters, **kwargs
-                )
+                return original_init(self, cls.subevent_code, parameters, **kwargs)
 
             cls.__init__ = init
 
             # Register a factory for this class
-            HCI_Event.meta_event_classes[cls.subevent_code] = cls
+            cls.subevent_classes[cls.subevent_code] = cls
 
             return cls
 
         return inner
 
     @classmethod
+    def subevent_name(cls, subevent_code):
+        subevent_name = cls.subevent_names.get(subevent_code)
+        if subevent_name is not None:
+            return subevent_name
+
+        return f'{cls.__name__.upper()}[0x{subevent_code:02X}]'
+
+    @staticmethod
+    def subevent_map(symbols: Dict[str, Any]) -> Dict[int, str]:
+        return {
+            subevent_code: subevent_name
+            for (subevent_name, subevent_code) in symbols.items()
+            if subevent_name.startswith('HCI_') and subevent_name.endswith('_EVENT')
+        }
+
+    @classmethod
+    def register_subevents(cls, symbols: Dict[str, Any]) -> None:
+        cls.subevent_names.update(cls.subevent_map(symbols))
+
+    @classmethod
     def from_parameters(cls, parameters):
         self = cls.__new__(cls)
-        HCI_LE_Meta_Event.__init__(self, self.subevent_code, parameters)
+        HCI_Extended_Event.__init__(self, self.subevent_code, parameters)
         if fields := getattr(self, 'fields', None):
             HCI_Object.init_from_bytes(self, parameters, 1, fields)
         return self
 
-    @staticmethod
-    def subevent_name(subevent_code):
-        return name_or_number(HCI_SUBEVENT_NAMES, subevent_code)
-
     def __init__(self, subevent_code, parameters, **kwargs):
         self.subevent_code = subevent_code
         if parameters is None and (fields := getattr(self, 'fields', None)) and kwargs:
             parameters = bytes([subevent_code]) + HCI_Object.dict_to_bytes(
                 kwargs, fields
             )
-        super().__init__(HCI_LE_META_EVENT, parameters, **kwargs)
+        super().__init__(self.event_code, parameters, **kwargs)
 
         # Override the name in order to adopt the subevent name instead
         self.name = self.subevent_name(subevent_code)
 
-    def __str__(self):
-        result = color(self.subevent_name(self.subevent_code), 'magenta')
-        if fields := getattr(self, 'fields', None):
-            result += ':\n' + HCI_Object.format_fields(self.__dict__, fields, '  ')
-        else:
-            if self.parameters:
-                result += f': {self.parameters.hex()}'
-        return result
+
+# -----------------------------------------------------------------------------
+class HCI_LE_Meta_Event(HCI_Extended_Event):
+    '''
+    See Bluetooth spec @ 7.7.65 LE Meta Event
+    '''
+
+    event_code: int = HCI_LE_META_EVENT
+    subevent_classes = {}
+
+    @staticmethod
+    def subevent_map(symbols: Dict[str, Any]) -> Dict[int, str]:
+        return {
+            subevent_code: subevent_name
+            for (subevent_name, subevent_code) in symbols.items()
+            if subevent_name.startswith('HCI_LE_') and subevent_name.endswith('_EVENT')
+        }
+
+
+HCI_LE_Meta_Event.register_subevents(globals())
+
+
+# -----------------------------------------------------------------------------
+class HCI_Vendor_Event(HCI_Extended_Event):
+    event_code: int = HCI_VENDOR_EVENT
+    subevent_classes = {}
 
 
 # -----------------------------------------------------------------------------
@@ -4591,7 +4673,7 @@ class HCI_LE_Advertising_Report_Event(HCI_LE_Meta_Event):
         return f'{color(self.subevent_name(self.subevent_code), "magenta")}:\n{reports}'
 
 
-HCI_Event.meta_event_classes[
+HCI_LE_Meta_Event.subevent_classes[
     HCI_LE_ADVERTISING_REPORT_EVENT
 ] = HCI_LE_Advertising_Report_Event
 
@@ -4845,7 +4927,7 @@ class HCI_LE_Extended_Advertising_Report_Event(HCI_LE_Meta_Event):
         return f'{color(self.subevent_name(self.subevent_code), "magenta")}:\n{reports}'
 
 
-HCI_Event.meta_event_classes[
+HCI_LE_Meta_Event.subevent_classes[
     HCI_LE_EXTENDED_ADVERTISING_REPORT_EVENT
 ] = HCI_LE_Extended_Advertising_Report_Event
 
@@ -5086,6 +5168,7 @@ class HCI_Command_Complete_Event(HCI_Event):
     '''
 
     return_parameters = b''
+    command_opcode: int
 
     def map_return_parameters(self, return_parameters):
         '''Map simple 'status' return parameters to their named constant form'''
@@ -5118,11 +5201,11 @@ class HCI_Command_Complete_Event(HCI_Event):
             self.return_parameters = self.return_parameters[0]
         else:
             cls = HCI_Command.command_classes.get(self.command_opcode)
-            if cls and cls.return_parameters_fields:
-                self.return_parameters = HCI_Object.from_bytes(
-                    self.return_parameters, 0, cls.return_parameters_fields
-                )
-                self.return_parameters.fields = cls.return_parameters_fields
+            if cls:
+                # Try to parse the return parameters bytes into an object.
+                return_parameters = cls.parse_return_parameters(self.return_parameters)
+                if return_parameters is not None:
+                    self.return_parameters = return_parameters
 
         return self
 
@@ -5605,7 +5688,7 @@ class HCI_Remote_Host_Supported_Features_Notification_Event(HCI_Event):
 
 
 # -----------------------------------------------------------------------------
-class HCI_AclDataPacket:
+class HCI_AclDataPacket(HCI_Packet):
     '''
     See Bluetooth spec @ 5.4.2 HCI ACL Data Packets
     '''
@@ -5613,7 +5696,7 @@ class HCI_AclDataPacket:
     hci_packet_type = HCI_ACL_DATA_PACKET
 
     @staticmethod
-    def from_bytes(packet):
+    def from_bytes(packet: bytes) -> HCI_AclDataPacket:
         # Read the header
         h, data_total_length = struct.unpack_from('<HH', packet, 1)
         connection_handle = h & 0xFFF
@@ -5655,12 +5738,14 @@ class HCI_AclDataPacket:
 
 # -----------------------------------------------------------------------------
 class HCI_AclDataPacketAssembler:
-    def __init__(self, callback):
+    current_data: Optional[bytes]
+
+    def __init__(self, callback: Callable[[bytes], Any]) -> None:
         self.callback = callback
         self.current_data = None
         self.l2cap_pdu_length = 0
 
-    def feed_packet(self, packet):
+    def feed_packet(self, packet: HCI_AclDataPacket) -> None:
         if packet.pb_flag in (
             HCI_ACL_PB_FIRST_NON_FLUSHABLE,
             HCI_ACL_PB_FIRST_FLUSHABLE,
@@ -5674,6 +5759,7 @@ class HCI_AclDataPacketAssembler:
                 return
             self.current_data += packet.data
 
+        assert self.current_data is not None
         if len(self.current_data) == self.l2cap_pdu_length + 4:
             # The packet is complete, invoke the callback
             logger.debug(f'<<< ACL PDU: {self.current_data.hex()}')
diff --git a/bumble/hfp.py b/bumble/hfp.py
index 6d9e428..bb00920 100644
--- a/bumble/hfp.py
+++ b/bumble/hfp.py
@@ -15,16 +15,19 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+import collections.abc
 import logging
 import asyncio
 import dataclasses
 import enum
 import traceback
-from typing import Dict, List, Union, Set
+import warnings
+from typing import Dict, List, Union, Set, TYPE_CHECKING
 
 from . import at
 from . import rfcomm
 
+from bumble.colors import color
 from bumble.core import (
     ProtocolError,
     BT_GENERIC_AUDIO_SERVICE,
@@ -48,6 +51,71 @@ from bumble.sdp import (
 # -----------------------------------------------------------------------------
 logger = logging.getLogger(__name__)
 
+# -----------------------------------------------------------------------------
+# Error
+# -----------------------------------------------------------------------------
+
+
+class HfpProtocolError(ProtocolError):
+    def __init__(self, error_name: str = '', details: str = ''):
+        super().__init__(None, 'hfp', error_name, details)
+
+
+# -----------------------------------------------------------------------------
+# Protocol Support
+# -----------------------------------------------------------------------------
+
+# -----------------------------------------------------------------------------
+class HfpProtocol:
+    dlc: rfcomm.DLC
+    buffer: str
+    lines: collections.deque
+    lines_available: asyncio.Event
+
+    def __init__(self, dlc: rfcomm.DLC) -> None:
+        warnings.warn("See HfProtocol", DeprecationWarning)
+        self.dlc = dlc
+        self.buffer = ''
+        self.lines = collections.deque()
+        self.lines_available = asyncio.Event()
+
+        dlc.sink = self.feed
+
+    def feed(self, data: Union[bytes, str]) -> None:
+        # Convert the data to a string if needed
+        if isinstance(data, bytes):
+            data = data.decode('utf-8')
+
+        logger.debug(f'<<< Data received: {data}')
+
+        # Add to the buffer and look for lines
+        self.buffer += data
+        while (separator := self.buffer.find('\r')) >= 0:
+            line = self.buffer[:separator].strip()
+            self.buffer = self.buffer[separator + 1 :]
+            if len(line) > 0:
+                self.on_line(line)
+
+    def on_line(self, line: str) -> None:
+        self.lines.append(line)
+        self.lines_available.set()
+
+    def send_command_line(self, line: str) -> None:
+        logger.debug(color(f'>>> {line}', 'yellow'))
+        self.dlc.write(line + '\r')
+
+    def send_response_line(self, line: str) -> None:
+        logger.debug(color(f'>>> {line}', 'yellow'))
+        self.dlc.write('\r\n' + line + '\r\n')
+
+    async def next_line(self) -> str:
+        await self.lines_available.wait()
+        line = self.lines.popleft()
+        if not self.lines:
+            self.lines_available.clear()
+        logger.debug(color(f'<<< {line}', 'green'))
+        return line
+
 
 # -----------------------------------------------------------------------------
 # Normative protocol definitions
@@ -302,8 +370,12 @@ class HfProtocol:
 
     dlc: rfcomm.DLC
     command_lock: asyncio.Lock
-    response_queue: asyncio.Queue
-    unsolicited_queue: asyncio.Queue
+    if TYPE_CHECKING:
+        response_queue: asyncio.Queue[AtResponse]
+        unsolicited_queue: asyncio.Queue[AtResponse]
+    else:
+        response_queue: asyncio.Queue
+        unsolicited_queue: asyncio.Queue
     read_buffer: bytearray
 
     def __init__(self, dlc: rfcomm.DLC, configuration: Configuration):
@@ -368,7 +440,7 @@ class HfProtocol:
         else:
             logger.warning(f"dropping unexpected response with code '{response.code}'")
 
-    # Send an AT command and wait for the peer resposne.
+    # Send an AT command and wait for the peer response.
     # Wait for the AT responses sent by the peer, to the status code.
     # Raises asyncio.TimeoutError if the status is not received
     # after a timeout (default 1 second).
@@ -390,7 +462,7 @@ class HfProtocol:
                 )
                 if result.code == 'OK':
                     if response_type == AtResponseType.SINGLE and len(responses) != 1:
-                        raise ProtocolError("NO ANSWER")
+                        raise HfpProtocolError("NO ANSWER")
 
                     if response_type == AtResponseType.MULTIPLE:
                         return responses
@@ -398,7 +470,7 @@ class HfProtocol:
                         return responses[0]
                     return None
                 if result.code in STATUS_CODES:
-                    raise ProtocolError(result.code)
+                    raise HfpProtocolError(result.code)
                 responses.append(result)
 
     # 4.2.1 Service Level Connection Initialization.
diff --git a/bumble/host.py b/bumble/host.py
index e41fd02..02caa46 100644
--- a/bumble/host.py
+++ b/bumble/host.py
@@ -15,23 +15,24 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
 import asyncio
 import collections
 import logging
 import struct
 
+from typing import Optional, TYPE_CHECKING, Dict, Callable, Awaitable
+
 from bumble.colors import color
 from bumble.l2cap import L2CAP_PDU
 from bumble.snoop import Snooper
 from bumble import drivers
 
-from typing import Optional
-
 from .hci import (
     Address,
     HCI_ACL_DATA_PACKET,
-    HCI_COMMAND_COMPLETE_EVENT,
     HCI_COMMAND_PACKET,
+    HCI_COMMAND_COMPLETE_EVENT,
     HCI_EVENT_PACKET,
     HCI_LE_READ_BUFFER_SIZE_COMMAND,
     HCI_LE_READ_LOCAL_SUPPORTED_FEATURES_COMMAND,
@@ -45,8 +46,11 @@ from .hci import (
     HCI_VERSION_BLUETOOTH_CORE_4_0,
     HCI_AclDataPacket,
     HCI_AclDataPacketAssembler,
+    HCI_Command,
+    HCI_Command_Complete_Event,
     HCI_Constant,
     HCI_Error,
+    HCI_Event,
     HCI_LE_Long_Term_Key_Request_Negative_Reply_Command,
     HCI_LE_Long_Term_Key_Request_Reply_Command,
     HCI_LE_Read_Buffer_Size_Command,
@@ -63,16 +67,19 @@ from .hci import (
     HCI_Read_Local_Version_Information_Command,
     HCI_Reset_Command,
     HCI_Set_Event_Mask_Command,
-    map_null_terminated_utf8_string,
 )
 from .core import (
     BT_BR_EDR_TRANSPORT,
-    BT_CENTRAL_ROLE,
     BT_LE_TRANSPORT,
     ConnectionPHY,
     ConnectionParameters,
+    InvalidStateError,
 )
 from .utils import AbortableEventEmitter
+from .transport.common import TransportLostError
+
+if TYPE_CHECKING:
+    from .transport.common import TransportSink, TransportSource
 
 
 # -----------------------------------------------------------------------------
@@ -96,27 +103,38 @@ HOST_HC_TOTAL_NUM_ACL_DATA_PACKETS        = 1
 
 # -----------------------------------------------------------------------------
 class Connection:
-    def __init__(self, host, handle, peer_address, transport):
+    def __init__(self, host: Host, handle: int, peer_address: Address, transport: int):
         self.host = host
         self.handle = handle
         self.peer_address = peer_address
         self.assembler = HCI_AclDataPacketAssembler(self.on_acl_pdu)
         self.transport = transport
 
-    def on_hci_acl_data_packet(self, packet):
+    def on_hci_acl_data_packet(self, packet: HCI_AclDataPacket) -> None:
         self.assembler.feed_packet(packet)
 
-    def on_acl_pdu(self, pdu):
+    def on_acl_pdu(self, pdu: bytes) -> None:
         l2cap_pdu = L2CAP_PDU.from_bytes(pdu)
         self.host.on_l2cap_pdu(self, l2cap_pdu.cid, l2cap_pdu.payload)
 
 
 # -----------------------------------------------------------------------------
 class Host(AbortableEventEmitter):
-    def __init__(self, controller_source=None, controller_sink=None):
+    connections: Dict[int, Connection]
+    acl_packet_queue: collections.deque[HCI_AclDataPacket]
+    hci_sink: TransportSink
+    long_term_key_provider: Optional[
+        Callable[[int, bytes, int], Awaitable[Optional[bytes]]]
+    ]
+    link_key_provider: Optional[Callable[[Address], Awaitable[Optional[bytes]]]]
+
+    def __init__(
+        self,
+        controller_source: Optional[TransportSource] = None,
+        controller_sink: Optional[TransportSink] = None,
+    ) -> None:
         super().__init__()
 
-        self.hci_sink = None
         self.hci_metadata = None
         self.ready = False  # True when we can accept incoming packets
         self.reset_done = False
@@ -296,7 +314,7 @@ class Host(AbortableEventEmitter):
         self.reset_done = True
 
     @property
-    def controller(self):
+    def controller(self) -> TransportSink:
         return self.hci_sink
 
     @controller.setter
@@ -305,13 +323,12 @@ class Host(AbortableEventEmitter):
         if controller:
             controller.set_packet_sink(self)
 
-    def set_packet_sink(self, sink):
+    def set_packet_sink(self, sink: TransportSink) -> None:
         self.hci_sink = sink
 
-    def send_hci_packet(self, packet):
+    def send_hci_packet(self, packet: HCI_Packet) -> None:
         if self.snooper:
             self.snooper.snoop(bytes(packet), Snooper.Direction.HOST_TO_CONTROLLER)
-
         self.hci_sink.on_packet(bytes(packet))
 
     async def send_command(self, command, check_result=False):
@@ -349,7 +366,7 @@ class Host(AbortableEventEmitter):
                 return response
             except Exception as error:
                 logger.warning(
-                    f'{color("!!! Exception while sending HCI packet:", "red")} {error}'
+                    f'{color("!!! Exception while sending command:", "red")} {error}'
                 )
                 raise error
             finally:
@@ -357,13 +374,13 @@ class Host(AbortableEventEmitter):
                 self.pending_response = None
 
     # Use this method to send a command from a task
-    def send_command_sync(self, command):
-        async def send_command(command):
+    def send_command_sync(self, command: HCI_Command) -> None:
+        async def send_command(command: HCI_Command) -> None:
             await self.send_command(command)
 
         asyncio.create_task(send_command(command))
 
-    def send_l2cap_pdu(self, connection_handle, cid, pdu):
+    def send_l2cap_pdu(self, connection_handle: int, cid: int, pdu: bytes) -> None:
         l2cap_pdu = bytes(L2CAP_PDU(cid, pdu))
 
         # Send the data to the controller via ACL packets
@@ -388,7 +405,7 @@ class Host(AbortableEventEmitter):
             offset += data_total_length
             bytes_remaining -= data_total_length
 
-    def queue_acl_packet(self, acl_packet):
+    def queue_acl_packet(self, acl_packet: HCI_AclDataPacket) -> None:
         self.acl_packet_queue.appendleft(acl_packet)
         self.check_acl_packet_queue()
 
@@ -398,7 +415,7 @@ class Host(AbortableEventEmitter):
                 f'{len(self.acl_packet_queue)} in queue'
             )
 
-    def check_acl_packet_queue(self):
+    def check_acl_packet_queue(self) -> None:
         # Send all we can (TODO: support different LE/Classic limits)
         while (
             len(self.acl_packet_queue) > 0
@@ -444,47 +461,53 @@ class Host(AbortableEventEmitter):
         ]
 
     # Packet Sink protocol (packets coming from the controller via HCI)
-    def on_packet(self, packet):
+    def on_packet(self, packet: bytes) -> None:
         hci_packet = HCI_Packet.from_bytes(packet)
         if self.ready or (
-            hci_packet.hci_packet_type == HCI_EVENT_PACKET
-            and hci_packet.event_code == HCI_COMMAND_COMPLETE_EVENT
+            isinstance(hci_packet, HCI_Command_Complete_Event)
             and hci_packet.command_opcode == HCI_RESET_COMMAND
         ):
             self.on_hci_packet(hci_packet)
         else:
             logger.debug('reset not done, ignoring packet from controller')
 
-    def on_hci_packet(self, packet):
+    def on_transport_lost(self):
+        # Called by the source when the transport has been lost.
+        if self.pending_response:
+            self.pending_response.set_exception(TransportLostError('transport lost'))
+
+        self.emit('flush')
+
+    def on_hci_packet(self, packet: HCI_Packet) -> None:
         logger.debug(f'{color("### CONTROLLER -> HOST", "green")}: {packet}')
 
         if self.snooper:
             self.snooper.snoop(bytes(packet), Snooper.Direction.CONTROLLER_TO_HOST)
 
         # If the packet is a command, invoke the handler for this packet
-        if packet.hci_packet_type == HCI_COMMAND_PACKET:
+        if isinstance(packet, HCI_Command):
             self.on_hci_command_packet(packet)
-        elif packet.hci_packet_type == HCI_EVENT_PACKET:
+        elif isinstance(packet, HCI_Event):
             self.on_hci_event_packet(packet)
-        elif packet.hci_packet_type == HCI_ACL_DATA_PACKET:
+        elif isinstance(packet, HCI_AclDataPacket):
             self.on_hci_acl_data_packet(packet)
         else:
             logger.warning(f'!!! unknown packet type {packet.hci_packet_type}')
 
-    def on_hci_command_packet(self, command):
+    def on_hci_command_packet(self, command: HCI_Command) -> None:
         logger.warning(f'!!! unexpected command packet: {command}')
 
-    def on_hci_event_packet(self, event):
+    def on_hci_event_packet(self, event: HCI_Event) -> None:
         handler_name = f'on_{event.name.lower()}'
         handler = getattr(self, handler_name, self.on_hci_event)
         handler(event)
 
-    def on_hci_acl_data_packet(self, packet):
+    def on_hci_acl_data_packet(self, packet: HCI_AclDataPacket) -> None:
         # Look for the connection to which this data belongs
         if connection := self.connections.get(packet.connection_handle):
             connection.on_hci_acl_data_packet(packet)
 
-    def on_l2cap_pdu(self, connection, cid, pdu):
+    def on_l2cap_pdu(self, connection: Connection, cid: int, pdu: bytes) -> None:
         self.emit('l2cap_pdu', connection.handle, cid, pdu)
 
     def on_command_processed(self, event):
@@ -822,6 +845,10 @@ class Host(AbortableEventEmitter):
             f'simple pairing complete for {event.bd_addr}: '
             f'status={HCI_Constant.status_name(event.status)}'
         )
+        if event.status == HCI_SUCCESS:
+            self.emit('classic_pairing', event.bd_addr)
+        else:
+            self.emit('classic_pairing_failure', event.bd_addr, event.status)
 
     def on_hci_pin_code_request_event(self, event):
         self.emit('pin_code_request', event.bd_addr)
diff --git a/bumble/l2cap.py b/bumble/l2cap.py
index 4464afc..cccb172 100644
--- a/bumble/l2cap.py
+++ b/bumble/l2cap.py
@@ -17,6 +17,7 @@
 # -----------------------------------------------------------------------------
 from __future__ import annotations
 import asyncio
+import enum
 import logging
 import struct
 
@@ -33,6 +34,7 @@ from typing import (
     Union,
     Deque,
     Iterable,
+    SupportsBytes,
     TYPE_CHECKING,
 )
 
@@ -47,6 +49,7 @@ from .hci import (
 
 if TYPE_CHECKING:
     from bumble.device import Connection
+    from bumble.host import Host
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -674,61 +677,40 @@ class L2CAP_LE_Flow_Control_Credit(L2CAP_Control_Frame):
 
 # -----------------------------------------------------------------------------
 class Channel(EventEmitter):
-    # States
-    CLOSED = 0x00
-    WAIT_CONNECT = 0x01
-    WAIT_CONNECT_RSP = 0x02
-    OPEN = 0x03
-    WAIT_DISCONNECT = 0x04
-    WAIT_CREATE = 0x05
-    WAIT_CREATE_RSP = 0x06
-    WAIT_MOVE = 0x07
-    WAIT_MOVE_RSP = 0x08
-    WAIT_MOVE_CONFIRM = 0x09
-    WAIT_CONFIRM_RSP = 0x0A
-
-    # CONFIG substates
-    WAIT_CONFIG = 0x10
-    WAIT_SEND_CONFIG = 0x11
-    WAIT_CONFIG_REQ_RSP = 0x12
-    WAIT_CONFIG_RSP = 0x13
-    WAIT_CONFIG_REQ = 0x14
-    WAIT_IND_FINAL_RSP = 0x15
-    WAIT_FINAL_RSP = 0x16
-    WAIT_CONTROL_IND = 0x17
-
-    STATE_NAMES = {
-        CLOSED: 'CLOSED',
-        WAIT_CONNECT: 'WAIT_CONNECT',
-        WAIT_CONNECT_RSP: 'WAIT_CONNECT_RSP',
-        OPEN: 'OPEN',
-        WAIT_DISCONNECT: 'WAIT_DISCONNECT',
-        WAIT_CREATE: 'WAIT_CREATE',
-        WAIT_CREATE_RSP: 'WAIT_CREATE_RSP',
-        WAIT_MOVE: 'WAIT_MOVE',
-        WAIT_MOVE_RSP: 'WAIT_MOVE_RSP',
-        WAIT_MOVE_CONFIRM: 'WAIT_MOVE_CONFIRM',
-        WAIT_CONFIRM_RSP: 'WAIT_CONFIRM_RSP',
-        WAIT_CONFIG: 'WAIT_CONFIG',
-        WAIT_SEND_CONFIG: 'WAIT_SEND_CONFIG',
-        WAIT_CONFIG_REQ_RSP: 'WAIT_CONFIG_REQ_RSP',
-        WAIT_CONFIG_RSP: 'WAIT_CONFIG_RSP',
-        WAIT_CONFIG_REQ: 'WAIT_CONFIG_REQ',
-        WAIT_IND_FINAL_RSP: 'WAIT_IND_FINAL_RSP',
-        WAIT_FINAL_RSP: 'WAIT_FINAL_RSP',
-        WAIT_CONTROL_IND: 'WAIT_CONTROL_IND',
-    }
+    class State(enum.IntEnum):
+        # States
+        CLOSED = 0x00
+        WAIT_CONNECT = 0x01
+        WAIT_CONNECT_RSP = 0x02
+        OPEN = 0x03
+        WAIT_DISCONNECT = 0x04
+        WAIT_CREATE = 0x05
+        WAIT_CREATE_RSP = 0x06
+        WAIT_MOVE = 0x07
+        WAIT_MOVE_RSP = 0x08
+        WAIT_MOVE_CONFIRM = 0x09
+        WAIT_CONFIRM_RSP = 0x0A
+
+        # CONFIG substates
+        WAIT_CONFIG = 0x10
+        WAIT_SEND_CONFIG = 0x11
+        WAIT_CONFIG_REQ_RSP = 0x12
+        WAIT_CONFIG_RSP = 0x13
+        WAIT_CONFIG_REQ = 0x14
+        WAIT_IND_FINAL_RSP = 0x15
+        WAIT_FINAL_RSP = 0x16
+        WAIT_CONTROL_IND = 0x17
 
     connection_result: Optional[asyncio.Future[None]]
     disconnection_result: Optional[asyncio.Future[None]]
     response: Optional[asyncio.Future[bytes]]
     sink: Optional[Callable[[bytes], Any]]
-    state: int
+    state: State
     connection: Connection
 
     def __init__(
         self,
-        manager: 'ChannelManager',
+        manager: ChannelManager,
         connection: Connection,
         signaling_cid: int,
         psm: int,
@@ -739,7 +721,7 @@ class Channel(EventEmitter):
         self.manager = manager
         self.connection = connection
         self.signaling_cid = signaling_cid
-        self.state = Channel.CLOSED
+        self.state = self.State.CLOSED
         self.mtu = mtu
         self.psm = psm
         self.source_cid = source_cid
@@ -749,30 +731,28 @@ class Channel(EventEmitter):
         self.disconnection_result = None
         self.sink = None
 
-    def change_state(self, new_state: int) -> None:
-        logger.debug(
-            f'{self} state change -> {color(Channel.STATE_NAMES[new_state], "cyan")}'
-        )
+    def _change_state(self, new_state: State) -> None:
+        logger.debug(f'{self} state change -> {color(new_state.name, "cyan")}')
         self.state = new_state
 
-    def send_pdu(self, pdu) -> None:
+    def send_pdu(self, pdu: Union[SupportsBytes, bytes]) -> None:
         self.manager.send_pdu(self.connection, self.destination_cid, pdu)
 
-    def send_control_frame(self, frame) -> None:
+    def send_control_frame(self, frame: L2CAP_Control_Frame) -> None:
         self.manager.send_control_frame(self.connection, self.signaling_cid, frame)
 
-    async def send_request(self, request) -> bytes:
+    async def send_request(self, request: SupportsBytes) -> bytes:
         # Check that there isn't already a request pending
         if self.response:
             raise InvalidStateError('request already pending')
-        if self.state != Channel.OPEN:
+        if self.state != self.State.OPEN:
             raise InvalidStateError('channel not open')
 
         self.response = asyncio.get_running_loop().create_future()
         self.send_pdu(request)
         return await self.response
 
-    def on_pdu(self, pdu) -> None:
+    def on_pdu(self, pdu: bytes) -> None:
         if self.response:
             self.response.set_result(pdu)
             self.response = None
@@ -785,14 +765,14 @@ class Channel(EventEmitter):
             )
 
     async def connect(self) -> None:
-        if self.state != Channel.CLOSED:
+        if self.state != self.State.CLOSED:
             raise InvalidStateError('invalid state')
 
         # Check that we can start a new connection
         if self.connection_result:
             raise RuntimeError('connection already pending')
 
-        self.change_state(Channel.WAIT_CONNECT_RSP)
+        self._change_state(self.State.WAIT_CONNECT_RSP)
         self.send_control_frame(
             L2CAP_Connection_Request(
                 identifier=self.manager.next_identifier(self.connection),
@@ -812,10 +792,10 @@ class Channel(EventEmitter):
             self.connection_result = None
 
     async def disconnect(self) -> None:
-        if self.state != Channel.OPEN:
+        if self.state != self.State.OPEN:
             raise InvalidStateError('invalid state')
 
-        self.change_state(Channel.WAIT_DISCONNECT)
+        self._change_state(self.State.WAIT_DISCONNECT)
         self.send_control_frame(
             L2CAP_Disconnection_Request(
                 identifier=self.manager.next_identifier(self.connection),
@@ -830,8 +810,8 @@ class Channel(EventEmitter):
         return await self.disconnection_result
 
     def abort(self) -> None:
-        if self.state == self.OPEN:
-            self.change_state(self.CLOSED)
+        if self.state == self.State.OPEN:
+            self._change_state(self.State.CLOSED)
             self.emit('close')
 
     def send_configure_request(self) -> None:
@@ -854,7 +834,7 @@ class Channel(EventEmitter):
 
     def on_connection_request(self, request) -> None:
         self.destination_cid = request.source_cid
-        self.change_state(Channel.WAIT_CONNECT)
+        self._change_state(self.State.WAIT_CONNECT)
         self.send_control_frame(
             L2CAP_Connection_Response(
                 identifier=request.identifier,
@@ -864,24 +844,24 @@ class Channel(EventEmitter):
                 status=0x0000,
             )
         )
-        self.change_state(Channel.WAIT_CONFIG)
+        self._change_state(self.State.WAIT_CONFIG)
         self.send_configure_request()
-        self.change_state(Channel.WAIT_CONFIG_REQ_RSP)
+        self._change_state(self.State.WAIT_CONFIG_REQ_RSP)
 
     def on_connection_response(self, response):
-        if self.state != Channel.WAIT_CONNECT_RSP:
+        if self.state != self.State.WAIT_CONNECT_RSP:
             logger.warning(color('invalid state', 'red'))
             return
 
         if response.result == L2CAP_Connection_Response.CONNECTION_SUCCESSFUL:
             self.destination_cid = response.destination_cid
-            self.change_state(Channel.WAIT_CONFIG)
+            self._change_state(self.State.WAIT_CONFIG)
             self.send_configure_request()
-            self.change_state(Channel.WAIT_CONFIG_REQ_RSP)
+            self._change_state(self.State.WAIT_CONFIG_REQ_RSP)
         elif response.result == L2CAP_Connection_Response.CONNECTION_PENDING:
             pass
         else:
-            self.change_state(Channel.CLOSED)
+            self._change_state(self.State.CLOSED)
             self.connection_result.set_exception(
                 ProtocolError(
                     response.result,
@@ -893,9 +873,9 @@ class Channel(EventEmitter):
 
     def on_configure_request(self, request) -> None:
         if self.state not in (
-            Channel.WAIT_CONFIG,
-            Channel.WAIT_CONFIG_REQ,
-            Channel.WAIT_CONFIG_REQ_RSP,
+            self.State.WAIT_CONFIG,
+            self.State.WAIT_CONFIG_REQ,
+            self.State.WAIT_CONFIG_REQ_RSP,
         ):
             logger.warning(color('invalid state', 'red'))
             return
@@ -916,25 +896,28 @@ class Channel(EventEmitter):
                 options=request.options,  # TODO: don't accept everything blindly
             )
         )
-        if self.state == Channel.WAIT_CONFIG:
-            self.change_state(Channel.WAIT_SEND_CONFIG)
+        if self.state == self.State.WAIT_CONFIG:
+            self._change_state(self.State.WAIT_SEND_CONFIG)
             self.send_configure_request()
-            self.change_state(Channel.WAIT_CONFIG_RSP)
-        elif self.state == Channel.WAIT_CONFIG_REQ:
-            self.change_state(Channel.OPEN)
+            self._change_state(self.State.WAIT_CONFIG_RSP)
+        elif self.state == self.State.WAIT_CONFIG_REQ:
+            self._change_state(self.State.OPEN)
             if self.connection_result:
                 self.connection_result.set_result(None)
                 self.connection_result = None
             self.emit('open')
-        elif self.state == Channel.WAIT_CONFIG_REQ_RSP:
-            self.change_state(Channel.WAIT_CONFIG_RSP)
+        elif self.state == self.State.WAIT_CONFIG_REQ_RSP:
+            self._change_state(self.State.WAIT_CONFIG_RSP)
 
     def on_configure_response(self, response) -> None:
         if response.result == L2CAP_Configure_Response.SUCCESS:
-            if self.state == Channel.WAIT_CONFIG_REQ_RSP:
-                self.change_state(Channel.WAIT_CONFIG_REQ)
-            elif self.state in (Channel.WAIT_CONFIG_RSP, Channel.WAIT_CONTROL_IND):
-                self.change_state(Channel.OPEN)
+            if self.state == self.State.WAIT_CONFIG_REQ_RSP:
+                self._change_state(self.State.WAIT_CONFIG_REQ)
+            elif self.state in (
+                self.State.WAIT_CONFIG_RSP,
+                self.State.WAIT_CONTROL_IND,
+            ):
+                self._change_state(self.State.OPEN)
                 if self.connection_result:
                     self.connection_result.set_result(None)
                     self.connection_result = None
@@ -964,7 +947,7 @@ class Channel(EventEmitter):
             # TODO: decide how to fail gracefully
 
     def on_disconnection_request(self, request) -> None:
-        if self.state in (Channel.OPEN, Channel.WAIT_DISCONNECT):
+        if self.state in (self.State.OPEN, self.State.WAIT_DISCONNECT):
             self.send_control_frame(
                 L2CAP_Disconnection_Response(
                     identifier=request.identifier,
@@ -972,14 +955,14 @@ class Channel(EventEmitter):
                     source_cid=request.source_cid,
                 )
             )
-            self.change_state(Channel.CLOSED)
+            self._change_state(self.State.CLOSED)
             self.emit('close')
             self.manager.on_channel_closed(self)
         else:
             logger.warning(color('invalid state', 'red'))
 
     def on_disconnection_response(self, response) -> None:
-        if self.state != Channel.WAIT_DISCONNECT:
+        if self.state != self.State.WAIT_DISCONNECT:
             logger.warning(color('invalid state', 'red'))
             return
 
@@ -990,7 +973,7 @@ class Channel(EventEmitter):
             logger.warning('unexpected source or destination CID')
             return
 
-        self.change_state(Channel.CLOSED)
+        self._change_state(self.State.CLOSED)
         if self.disconnection_result:
             self.disconnection_result.set_result(None)
             self.disconnection_result = None
@@ -1002,7 +985,7 @@ class Channel(EventEmitter):
             f'Channel({self.source_cid}->{self.destination_cid}, '
             f'PSM={self.psm}, '
             f'MTU={self.mtu}, '
-            f'state={Channel.STATE_NAMES[self.state]})'
+            f'state={self.state.name})'
         )
 
 
@@ -1012,36 +995,24 @@ class LeConnectionOrientedChannel(EventEmitter):
     LE Credit-based Connection Oriented Channel
     """
 
-    INIT = 0
-    CONNECTED = 1
-    CONNECTING = 2
-    DISCONNECTING = 3
-    DISCONNECTED = 4
-    CONNECTION_ERROR = 5
-
-    STATE_NAMES = {
-        INIT: 'INIT',
-        CONNECTED: 'CONNECTED',
-        CONNECTING: 'CONNECTING',
-        DISCONNECTING: 'DISCONNECTING',
-        DISCONNECTED: 'DISCONNECTED',
-        CONNECTION_ERROR: 'CONNECTION_ERROR',
-    }
+    class State(enum.IntEnum):
+        INIT = 0
+        CONNECTED = 1
+        CONNECTING = 2
+        DISCONNECTING = 3
+        DISCONNECTED = 4
+        CONNECTION_ERROR = 5
 
     out_queue: Deque[bytes]
     connection_result: Optional[asyncio.Future[LeConnectionOrientedChannel]]
     disconnection_result: Optional[asyncio.Future[None]]
     out_sdu: Optional[bytes]
-    state: int
+    state: State
     connection: Connection
 
-    @staticmethod
-    def state_name(state: int) -> str:
-        return name_or_number(LeConnectionOrientedChannel.STATE_NAMES, state)
-
     def __init__(
         self,
-        manager: 'ChannelManager',
+        manager: ChannelManager,
         connection: Connection,
         le_psm: int,
         source_cid: int,
@@ -1081,30 +1052,28 @@ class LeConnectionOrientedChannel(EventEmitter):
         self.drained.set()
 
         if connected:
-            self.state = LeConnectionOrientedChannel.CONNECTED
+            self.state = self.State.CONNECTED
         else:
-            self.state = LeConnectionOrientedChannel.INIT
+            self.state = self.State.INIT
 
-    def change_state(self, new_state: int) -> None:
-        logger.debug(
-            f'{self} state change -> {color(self.state_name(new_state), "cyan")}'
-        )
+    def _change_state(self, new_state: State) -> None:
+        logger.debug(f'{self} state change -> {color(new_state.name, "cyan")}')
         self.state = new_state
 
-        if new_state == self.CONNECTED:
+        if new_state == self.State.CONNECTED:
             self.emit('open')
-        elif new_state == self.DISCONNECTED:
+        elif new_state == self.State.DISCONNECTED:
             self.emit('close')
 
-    def send_pdu(self, pdu) -> None:
+    def send_pdu(self, pdu: Union[SupportsBytes, bytes]) -> None:
         self.manager.send_pdu(self.connection, self.destination_cid, pdu)
 
-    def send_control_frame(self, frame) -> None:
+    def send_control_frame(self, frame: L2CAP_Control_Frame) -> None:
         self.manager.send_control_frame(self.connection, L2CAP_LE_SIGNALING_CID, frame)
 
     async def connect(self) -> LeConnectionOrientedChannel:
         # Check that we're in the right state
-        if self.state != self.INIT:
+        if self.state != self.State.INIT:
             raise InvalidStateError('not in a connectable state')
 
         # Check that we can start a new connection
@@ -1112,7 +1081,7 @@ class LeConnectionOrientedChannel(EventEmitter):
         if identifier in self.manager.le_coc_requests:
             raise RuntimeError('too many concurrent connection requests')
 
-        self.change_state(self.CONNECTING)
+        self._change_state(self.State.CONNECTING)
         request = L2CAP_LE_Credit_Based_Connection_Request(
             identifier=identifier,
             le_psm=self.le_psm,
@@ -1132,10 +1101,10 @@ class LeConnectionOrientedChannel(EventEmitter):
 
     async def disconnect(self) -> None:
         # Check that we're connected
-        if self.state != self.CONNECTED:
+        if self.state != self.State.CONNECTED:
             raise InvalidStateError('not connected')
 
-        self.change_state(self.DISCONNECTING)
+        self._change_state(self.State.DISCONNECTING)
         self.flush_output()
         self.send_control_frame(
             L2CAP_Disconnection_Request(
@@ -1151,15 +1120,15 @@ class LeConnectionOrientedChannel(EventEmitter):
         return await self.disconnection_result
 
     def abort(self) -> None:
-        if self.state == self.CONNECTED:
-            self.change_state(self.DISCONNECTED)
+        if self.state == self.State.CONNECTED:
+            self._change_state(self.State.DISCONNECTED)
 
-    def on_pdu(self, pdu) -> None:
+    def on_pdu(self, pdu: bytes) -> None:
         if self.sink is None:
             logger.warning('received pdu without a sink')
             return
 
-        if self.state != self.CONNECTED:
+        if self.state != self.State.CONNECTED:
             logger.warning('received PDU while not connected, dropping')
 
         # Manage the peer credits
@@ -1238,7 +1207,7 @@ class LeConnectionOrientedChannel(EventEmitter):
             self.credits = response.initial_credits
             self.connected = True
             self.connection_result.set_result(self)
-            self.change_state(self.CONNECTED)
+            self._change_state(self.State.CONNECTED)
         else:
             self.connection_result.set_exception(
                 ProtocolError(
@@ -1249,7 +1218,7 @@ class LeConnectionOrientedChannel(EventEmitter):
                     ),
                 )
             )
-            self.change_state(self.CONNECTION_ERROR)
+            self._change_state(self.State.CONNECTION_ERROR)
 
         # Cleanup
         self.connection_result = None
@@ -1269,11 +1238,11 @@ class LeConnectionOrientedChannel(EventEmitter):
                 source_cid=request.source_cid,
             )
         )
-        self.change_state(self.DISCONNECTED)
+        self._change_state(self.State.DISCONNECTED)
         self.flush_output()
 
     def on_disconnection_response(self, response) -> None:
-        if self.state != self.DISCONNECTING:
+        if self.state != self.State.DISCONNECTING:
             logger.warning(color('invalid state', 'red'))
             return
 
@@ -1284,7 +1253,7 @@ class LeConnectionOrientedChannel(EventEmitter):
             logger.warning('unexpected source or destination CID')
             return
 
-        self.change_state(self.DISCONNECTED)
+        self._change_state(self.State.DISCONNECTED)
         if self.disconnection_result:
             self.disconnection_result.set_result(None)
             self.disconnection_result = None
@@ -1337,7 +1306,7 @@ class LeConnectionOrientedChannel(EventEmitter):
                 return
 
     def write(self, data: bytes) -> None:
-        if self.state != self.CONNECTED:
+        if self.state != self.State.CONNECTED:
             logger.warning('not connected, dropping data')
             return
 
@@ -1365,7 +1334,7 @@ class LeConnectionOrientedChannel(EventEmitter):
     def __str__(self) -> str:
         return (
             f'CoC({self.source_cid}->{self.destination_cid}, '
-            f'State={self.state_name(self.state)}, '
+            f'State={self.state.name}, '
             f'PSM={self.le_psm}, '
             f'MTU={self.mtu}/{self.peer_mtu}, '
             f'MPS={self.mps}/{self.peer_mps}, '
@@ -1384,6 +1353,8 @@ class ChannelManager:
     ]
     le_coc_requests: Dict[int, L2CAP_LE_Credit_Based_Connection_Request]
     fixed_channels: Dict[int, Optional[Callable[[int, bytes], Any]]]
+    _host: Optional[Host]
+    connection_parameters_update_response: Optional[asyncio.Future[int]]
 
     def __init__(
         self,
@@ -1405,13 +1376,15 @@ class ChannelManager:
         self.le_coc_requests = {}  # LE CoC connection requests, by identifier
         self.extended_features = extended_features
         self.connectionless_mtu = connectionless_mtu
+        self.connection_parameters_update_response = None
 
     @property
-    def host(self):
+    def host(self) -> Host:
+        assert self._host
         return self._host
 
     @host.setter
-    def host(self, host):
+    def host(self, host: Host) -> None:
         if self._host is not None:
             self._host.remove_listener('disconnection', self.on_disconnection)
         self._host = host
@@ -1565,7 +1538,7 @@ class ChannelManager:
         if connection_handle in self.identifiers:
             del self.identifiers[connection_handle]
 
-    def send_pdu(self, connection, cid: int, pdu) -> None:
+    def send_pdu(self, connection, cid: int, pdu: Union[SupportsBytes, bytes]) -> None:
         pdu_str = pdu.hex() if isinstance(pdu, bytes) else str(pdu)
         logger.debug(
             f'{color(">>> Sending L2CAP PDU", "blue")} '
@@ -1574,7 +1547,7 @@ class ChannelManager:
         )
         self.host.send_l2cap_pdu(connection.handle, cid, bytes(pdu))
 
-    def on_pdu(self, connection: Connection, cid: int, pdu) -> None:
+    def on_pdu(self, connection: Connection, cid: int, pdu: bytes) -> None:
         if cid in (L2CAP_SIGNALING_CID, L2CAP_LE_SIGNALING_CID):
             # Parse the L2CAP payload into a Control Frame object
             control_frame = L2CAP_Control_Frame.from_bytes(pdu)
@@ -1596,7 +1569,7 @@ class ChannelManager:
             channel.on_pdu(pdu)
 
     def send_control_frame(
-        self, connection: Connection, cid: int, control_frame
+        self, connection: Connection, cid: int, control_frame: L2CAP_Control_Frame
     ) -> None:
         logger.debug(
             f'{color(">>> Sending L2CAP Signaling Control Frame", "blue")} '
@@ -1605,7 +1578,9 @@ class ChannelManager:
         )
         self.host.send_l2cap_pdu(connection.handle, cid, bytes(control_frame))
 
-    def on_control_frame(self, connection: Connection, cid: int, control_frame) -> None:
+    def on_control_frame(
+        self, connection: Connection, cid: int, control_frame: L2CAP_Control_Frame
+    ) -> None:
         logger.debug(
             f'{color("<<< Received L2CAP Signaling Control Frame", "green")} '
             f'on connection [0x{connection.handle:04X}] (CID={cid}) '
@@ -1859,11 +1834,45 @@ class ChannelManager:
                 ),
             )
 
+    async def update_connection_parameters(
+        self,
+        connection: Connection,
+        interval_min: int,
+        interval_max: int,
+        latency: int,
+        timeout: int,
+    ) -> int:
+        # Check that there isn't already a request pending
+        if self.connection_parameters_update_response:
+            raise InvalidStateError('request already pending')
+        self.connection_parameters_update_response = (
+            asyncio.get_running_loop().create_future()
+        )
+        self.send_control_frame(
+            connection,
+            L2CAP_LE_SIGNALING_CID,
+            L2CAP_Connection_Parameter_Update_Request(
+                interval_min=interval_min,
+                interval_max=interval_max,
+                latency=latency,
+                timeout=timeout,
+            ),
+        )
+        return await self.connection_parameters_update_response
+
     def on_l2cap_connection_parameter_update_response(
         self, connection: Connection, cid: int, response
     ) -> None:
-        # TODO: check response
-        pass
+        if self.connection_parameters_update_response:
+            self.connection_parameters_update_response.set_result(response.result)
+            self.connection_parameters_update_response = None
+        else:
+            logger.warning(
+                color(
+                    'received l2cap_connection_parameter_update_response without a pending request',
+                    'red',
+                )
+            )
 
     def on_l2cap_le_credit_based_connection_request(
         self, connection: Connection, cid: int, request
@@ -2072,7 +2081,8 @@ class ChannelManager:
         # Connect
         try:
             await channel.connect()
-        except Exception:
+        except Exception as e:
             del connection_channels[source_cid]
+            raise e
 
         return channel
diff --git a/bumble/pandora/security.py b/bumble/pandora/security.py
index fb6fd6f..0f31512 100644
--- a/bumble/pandora/security.py
+++ b/bumble/pandora/security.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import asyncio
+import contextlib
 import grpc
 import logging
 
@@ -27,8 +28,8 @@ from bumble.core import (
 )
 from bumble.device import Connection as BumbleConnection, Device
 from bumble.hci import HCI_Error
+from bumble.utils import EventWatcher
 from bumble.pairing import PairingConfig, PairingDelegate as BasePairingDelegate
-from contextlib import suppress
 from google.protobuf import any_pb2  # pytype: disable=pyi-error
 from google.protobuf import empty_pb2  # pytype: disable=pyi-error
 from google.protobuf import wrappers_pb2  # pytype: disable=pyi-error
@@ -232,7 +233,11 @@ class SecurityService(SecurityServicer):
                 sc=config.pairing_sc_enable,
                 mitm=config.pairing_mitm_enable,
                 bonding=config.pairing_bonding_enable,
-                identity_address_type=config.identity_address_type,
+                identity_address_type=(
+                    PairingConfig.AddressType.PUBLIC
+                    if connection.self_address.is_public
+                    else config.identity_address_type
+                ),
                 delegate=PairingDelegate(
                     connection,
                     self,
@@ -294,23 +299,35 @@ class SecurityService(SecurityServicer):
             try:
                 self.log.debug('Pair...')
 
-                if (
-                    connection.transport == BT_LE_TRANSPORT
-                    and connection.role == BT_PERIPHERAL_ROLE
-                ):
-                    wait_for_security: asyncio.Future[
-                        bool
-                    ] = asyncio.get_running_loop().create_future()
-                    connection.on("pairing", lambda *_: wait_for_security.set_result(True))  # type: ignore
-                    connection.on("pairing_failure", wait_for_security.set_exception)
+                security_result = asyncio.get_running_loop().create_future()
+
+                with contextlib.closing(EventWatcher()) as watcher:
+
+                    @watcher.on(connection, 'pairing')
+                    def on_pairing(*_: Any) -> None:
+                        security_result.set_result('success')
 
-                    connection.request_pairing()
+                    @watcher.on(connection, 'pairing_failure')
+                    def on_pairing_failure(*_: Any) -> None:
+                        security_result.set_result('pairing_failure')
 
-                    await wait_for_security
-                else:
-                    await connection.pair()
+                    @watcher.on(connection, 'disconnection')
+                    def on_disconnection(*_: Any) -> None:
+                        security_result.set_result('connection_died')
 
-                self.log.debug('Paired')
+                    if (
+                        connection.transport == BT_LE_TRANSPORT
+                        and connection.role == BT_PERIPHERAL_ROLE
+                    ):
+                        connection.request_pairing()
+                    else:
+                        await connection.pair()
+
+                    result = await security_result
+
+                self.log.debug(f'Pairing session complete, status={result}')
+                if result != 'success':
+                    return SecureResponse(**{result: empty_pb2.Empty()})
             except asyncio.CancelledError:
                 self.log.warning("Connection died during encryption")
                 return SecureResponse(connection_died=empty_pb2.Empty())
@@ -369,6 +386,7 @@ class SecurityService(SecurityServicer):
             str
         ] = asyncio.get_running_loop().create_future()
         authenticate_task: Optional[asyncio.Future[None]] = None
+        pair_task: Optional[asyncio.Future[None]] = None
 
         async def authenticate() -> None:
             assert connection
@@ -415,6 +433,10 @@ class SecurityService(SecurityServicer):
                 if authenticate_task is None:
                     authenticate_task = asyncio.create_task(authenticate())
 
+        def pair(*_: Any) -> None:
+            if self.need_pairing(connection, level):
+                pair_task = asyncio.create_task(connection.pair())
+
         listeners: Dict[str, Callable[..., None]] = {
             'disconnection': set_failure('connection_died'),
             'pairing_failure': set_failure('pairing_failure'),
@@ -423,6 +445,9 @@ class SecurityService(SecurityServicer):
             'pairing': try_set_success,
             'connection_authentication': try_set_success,
             'connection_encryption_change': on_encryption_change,
+            'classic_pairing': try_set_success,
+            'classic_pairing_failure': set_failure('pairing_failure'),
+            'security_request': pair,
         }
 
         # register event handlers
@@ -450,6 +475,15 @@ class SecurityService(SecurityServicer):
                 pass
             self.log.debug('Authenticated')
 
+        # wait for `pair` to finish if any
+        if pair_task is not None:
+            self.log.debug('Wait for authentication...')
+            try:
+                await pair_task  # type: ignore
+            except:
+                pass
+            self.log.debug('paired')
+
         return WaitSecurityResponse(**kwargs)
 
     def reached_security_level(
@@ -521,7 +555,7 @@ class SecurityStorageService(SecurityStorageServicer):
         self.log.debug(f"DeleteBond: {address}")
 
         if self.device.keystore is not None:
-            with suppress(KeyError):
+            with contextlib.suppress(KeyError):
                 await self.device.keystore.delete(str(address))
 
         return empty_pb2.Empty()
diff --git a/bumble/rfcomm.py b/bumble/rfcomm.py
index 0176a78..02c18fa 100644
--- a/bumble/rfcomm.py
+++ b/bumble/rfcomm.py
@@ -15,15 +15,37 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
+
 import logging
 import asyncio
+import enum
+from typing import Callable, Dict, List, Optional, Tuple, Union, TYPE_CHECKING
 
 from pyee import EventEmitter
-from typing import Optional, Tuple, Callable, Dict, Union
 
 from . import core, l2cap
 from .colors import color
-from .core import BT_BR_EDR_TRANSPORT, InvalidStateError, ProtocolError
+from .core import (
+    UUID,
+    BT_RFCOMM_PROTOCOL_ID,
+    BT_BR_EDR_TRANSPORT,
+    BT_L2CAP_PROTOCOL_ID,
+    InvalidStateError,
+    ProtocolError,
+)
+from .sdp import (
+    SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
+    SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
+    SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
+    SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
+    SDP_PUBLIC_BROWSE_ROOT,
+    DataElement,
+    ServiceAttribute,
+)
+
+if TYPE_CHECKING:
+    from bumble.device import Device, Connection
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -106,6 +128,50 @@ RFCOMM_DYNAMIC_CHANNEL_NUMBER_END   = 30
 
 
 # -----------------------------------------------------------------------------
+def make_service_sdp_records(
+    service_record_handle: int, channel: int, uuid: Optional[UUID] = None
+) -> List[ServiceAttribute]:
+    """
+    Create SDP records for an RFComm service given a channel number and an
+    optional UUID. A Service Class Attribute is included only if the UUID is not None.
+    """
+    records = [
+        ServiceAttribute(
+            SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
+            DataElement.unsigned_integer_32(service_record_handle),
+        ),
+        ServiceAttribute(
+            SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
+            DataElement.sequence([DataElement.uuid(SDP_PUBLIC_BROWSE_ROOT)]),
+        ),
+        ServiceAttribute(
+            SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
+            DataElement.sequence(
+                [
+                    DataElement.sequence([DataElement.uuid(BT_L2CAP_PROTOCOL_ID)]),
+                    DataElement.sequence(
+                        [
+                            DataElement.uuid(BT_RFCOMM_PROTOCOL_ID),
+                            DataElement.unsigned_integer_8(channel),
+                        ]
+                    ),
+                ]
+            ),
+        ),
+    ]
+
+    if uuid:
+        records.append(
+            ServiceAttribute(
+                SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
+                DataElement.sequence([DataElement.uuid(uuid)]),
+            )
+        )
+
+    return records
+
+
+# -----------------------------------------------------------------------------
 def compute_fcs(buffer: bytes) -> int:
     result = 0xFF
     for byte in buffer:
@@ -149,9 +215,9 @@ class RFCOMM_Frame:
         return RFCOMM_FRAME_TYPE_NAMES[self.type]
 
     @staticmethod
-    def parse_mcc(data) -> Tuple[int, int, bytes]:
+    def parse_mcc(data) -> Tuple[int, bool, bytes]:
         mcc_type = data[0] >> 2
-        c_r = (data[0] >> 1) & 1
+        c_r = bool((data[0] >> 1) & 1)
         length = data[1]
         if data[1] & 1:
             length >>= 1
@@ -192,7 +258,7 @@ class RFCOMM_Frame:
         )
 
     @staticmethod
-    def from_bytes(data: bytes):
+    def from_bytes(data: bytes) -> RFCOMM_Frame:
         # Extract fields
         dlci = (data[0] >> 2) & 0x3F
         c_r = (data[0] >> 1) & 0x01
@@ -215,7 +281,7 @@ class RFCOMM_Frame:
 
         return frame
 
-    def __bytes__(self):
+    def __bytes__(self) -> bytes:
         return (
             bytes([self.address, self.control])
             + self.length
@@ -223,7 +289,7 @@ class RFCOMM_Frame:
             + bytes([self.fcs])
         )
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'{color(self.type_name(), "yellow")}'
             f'(c/r={self.c_r},'
@@ -253,7 +319,7 @@ class RFCOMM_MCC_PN:
         max_frame_size: int,
         max_retransmissions: int,
         window_size: int,
-    ):
+    ) -> None:
         self.dlci = dlci
         self.cl = cl
         self.priority = priority
@@ -263,7 +329,7 @@ class RFCOMM_MCC_PN:
         self.window_size = window_size
 
     @staticmethod
-    def from_bytes(data: bytes):
+    def from_bytes(data: bytes) -> RFCOMM_MCC_PN:
         return RFCOMM_MCC_PN(
             dlci=data[0],
             cl=data[1],
@@ -274,7 +340,7 @@ class RFCOMM_MCC_PN:
             window_size=data[7],
         )
 
-    def __bytes__(self):
+    def __bytes__(self) -> bytes:
         return bytes(
             [
                 self.dlci & 0xFF,
@@ -288,7 +354,7 @@ class RFCOMM_MCC_PN:
             ]
         )
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'PN(dlci={self.dlci},'
             f'cl={self.cl},'
@@ -309,7 +375,9 @@ class RFCOMM_MCC_MSC:
     ic: int
     dv: int
 
-    def __init__(self, dlci: int, fc: int, rtc: int, rtr: int, ic: int, dv: int):
+    def __init__(
+        self, dlci: int, fc: int, rtc: int, rtr: int, ic: int, dv: int
+    ) -> None:
         self.dlci = dlci
         self.fc = fc
         self.rtc = rtc
@@ -318,7 +386,7 @@ class RFCOMM_MCC_MSC:
         self.dv = dv
 
     @staticmethod
-    def from_bytes(data: bytes):
+    def from_bytes(data: bytes) -> RFCOMM_MCC_MSC:
         return RFCOMM_MCC_MSC(
             dlci=data[0] >> 2,
             fc=data[1] >> 1 & 1,
@@ -328,7 +396,7 @@ class RFCOMM_MCC_MSC:
             dv=data[1] >> 7 & 1,
         )
 
-    def __bytes__(self):
+    def __bytes__(self) -> bytes:
         return bytes(
             [
                 (self.dlci << 2) | 3,
@@ -341,7 +409,7 @@ class RFCOMM_MCC_MSC:
             ]
         )
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f'MSC(dlci={self.dlci},'
             f'fc={self.fc},'
@@ -354,29 +422,24 @@ class RFCOMM_MCC_MSC:
 
 # -----------------------------------------------------------------------------
 class DLC(EventEmitter):
-    # States
-    INIT = 0x00
-    CONNECTING = 0x01
-    CONNECTED = 0x02
-    DISCONNECTING = 0x03
-    DISCONNECTED = 0x04
-    RESET = 0x05
-
-    STATE_NAMES = {
-        INIT: 'INIT',
-        CONNECTING: 'CONNECTING',
-        CONNECTED: 'CONNECTED',
-        DISCONNECTING: 'DISCONNECTING',
-        DISCONNECTED: 'DISCONNECTED',
-        RESET: 'RESET',
-    }
+    class State(enum.IntEnum):
+        INIT = 0x00
+        CONNECTING = 0x01
+        CONNECTED = 0x02
+        DISCONNECTING = 0x03
+        DISCONNECTED = 0x04
+        RESET = 0x05
 
     connection_result: Optional[asyncio.Future]
     sink: Optional[Callable[[bytes], None]]
 
     def __init__(
-        self, multiplexer, dlci: int, max_frame_size: int, initial_tx_credits: int
-    ):
+        self,
+        multiplexer: Multiplexer,
+        dlci: int,
+        max_frame_size: int,
+        initial_tx_credits: int,
+    ) -> None:
         super().__init__()
         self.multiplexer = multiplexer
         self.dlci = dlci
@@ -384,9 +447,9 @@ class DLC(EventEmitter):
         self.rx_threshold = self.rx_credits // 2
         self.tx_credits = initial_tx_credits
         self.tx_buffer = b''
-        self.state = DLC.INIT
+        self.state = DLC.State.INIT
         self.role = multiplexer.role
-        self.c_r = 1 if self.role == Multiplexer.INITIATOR else 0
+        self.c_r = 1 if self.role == Multiplexer.Role.INITIATOR else 0
         self.sink = None
         self.connection_result = None
 
@@ -396,14 +459,8 @@ class DLC(EventEmitter):
             max_frame_size, self.multiplexer.l2cap_channel.mtu - max_overhead
         )
 
-    @staticmethod
-    def state_name(state: int) -> str:
-        return DLC.STATE_NAMES[state]
-
-    def change_state(self, new_state: int) -> None:
-        logger.debug(
-            f'{self} state change -> {color(self.state_name(new_state), "magenta")}'
-        )
+    def change_state(self, new_state: State) -> None:
+        logger.debug(f'{self} state change -> {color(new_state.name, "magenta")}')
         self.state = new_state
 
     def send_frame(self, frame: RFCOMM_Frame) -> None:
@@ -413,8 +470,8 @@ class DLC(EventEmitter):
         handler = getattr(self, f'on_{frame.type_name()}_frame'.lower())
         handler(frame)
 
-    def on_sabm_frame(self, _frame) -> None:
-        if self.state != DLC.CONNECTING:
+    def on_sabm_frame(self, _frame: RFCOMM_Frame) -> None:
+        if self.state != DLC.State.CONNECTING:
             logger.warning(
                 color('!!! received SABM when not in CONNECTING state', 'red')
             )
@@ -430,11 +487,11 @@ class DLC(EventEmitter):
         logger.debug(f'>>> MCC MSC Command: {msc}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
 
-        self.change_state(DLC.CONNECTED)
+        self.change_state(DLC.State.CONNECTED)
         self.emit('open')
 
-    def on_ua_frame(self, _frame) -> None:
-        if self.state != DLC.CONNECTING:
+    def on_ua_frame(self, _frame: RFCOMM_Frame) -> None:
+        if self.state != DLC.State.CONNECTING:
             logger.warning(
                 color('!!! received SABM when not in CONNECTING state', 'red')
             )
@@ -448,14 +505,14 @@ class DLC(EventEmitter):
         logger.debug(f'>>> MCC MSC Command: {msc}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
 
-        self.change_state(DLC.CONNECTED)
+        self.change_state(DLC.State.CONNECTED)
         self.multiplexer.on_dlc_open_complete(self)
 
-    def on_dm_frame(self, frame) -> None:
+    def on_dm_frame(self, frame: RFCOMM_Frame) -> None:
         # TODO: handle all states
         pass
 
-    def on_disc_frame(self, _frame) -> None:
+    def on_disc_frame(self, _frame: RFCOMM_Frame) -> None:
         # TODO: handle all states
         self.send_frame(RFCOMM_Frame.ua(c_r=1 - self.c_r, dlci=self.dlci))
 
@@ -489,10 +546,10 @@ class DLC(EventEmitter):
         # Check if there's anything to send (including credits)
         self.process_tx()
 
-    def on_ui_frame(self, frame) -> None:
+    def on_ui_frame(self, frame: RFCOMM_Frame) -> None:
         pass
 
-    def on_mcc_msc(self, c_r, msc) -> None:
+    def on_mcc_msc(self, c_r: bool, msc: RFCOMM_MCC_MSC) -> None:
         if c_r:
             # Command
             logger.debug(f'<<< MCC MSC Command: {msc}')
@@ -507,15 +564,15 @@ class DLC(EventEmitter):
             logger.debug(f'<<< MCC MSC Response: {msc}')
 
     def connect(self) -> None:
-        if self.state != DLC.INIT:
+        if self.state != DLC.State.INIT:
             raise InvalidStateError('invalid state')
 
-        self.change_state(DLC.CONNECTING)
+        self.change_state(DLC.State.CONNECTING)
         self.connection_result = asyncio.get_running_loop().create_future()
         self.send_frame(RFCOMM_Frame.sabm(c_r=self.c_r, dlci=self.dlci))
 
     def accept(self) -> None:
-        if self.state != DLC.INIT:
+        if self.state != DLC.State.INIT:
             raise InvalidStateError('invalid state')
 
         pn = RFCOMM_MCC_PN(
@@ -530,7 +587,7 @@ class DLC(EventEmitter):
         mcc = RFCOMM_Frame.make_mcc(mcc_type=RFCOMM_MCC_PN_TYPE, c_r=0, data=bytes(pn))
         logger.debug(f'>>> PN Response: {pn}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
-        self.change_state(DLC.CONNECTING)
+        self.change_state(DLC.State.CONNECTING)
 
     def rx_credits_needed(self) -> int:
         if self.rx_credits <= self.rx_threshold:
@@ -592,34 +649,24 @@ class DLC(EventEmitter):
         # TODO
         pass
 
-    def __str__(self):
-        return f'DLC(dlci={self.dlci},state={self.state_name(self.state)})'
+    def __str__(self) -> str:
+        return f'DLC(dlci={self.dlci},state={self.state.name})'
 
 
 # -----------------------------------------------------------------------------
 class Multiplexer(EventEmitter):
-    # Roles
-    INITIATOR = 0x00
-    RESPONDER = 0x01
-
-    # States
-    INIT = 0x00
-    CONNECTING = 0x01
-    CONNECTED = 0x02
-    OPENING = 0x03
-    DISCONNECTING = 0x04
-    DISCONNECTED = 0x05
-    RESET = 0x06
-
-    STATE_NAMES = {
-        INIT: 'INIT',
-        CONNECTING: 'CONNECTING',
-        CONNECTED: 'CONNECTED',
-        OPENING: 'OPENING',
-        DISCONNECTING: 'DISCONNECTING',
-        DISCONNECTED: 'DISCONNECTED',
-        RESET: 'RESET',
-    }
+    class Role(enum.IntEnum):
+        INITIATOR = 0x00
+        RESPONDER = 0x01
+
+    class State(enum.IntEnum):
+        INIT = 0x00
+        CONNECTING = 0x01
+        CONNECTED = 0x02
+        OPENING = 0x03
+        DISCONNECTING = 0x04
+        DISCONNECTED = 0x05
+        RESET = 0x06
 
     connection_result: Optional[asyncio.Future]
     disconnection_result: Optional[asyncio.Future]
@@ -627,11 +674,11 @@ class Multiplexer(EventEmitter):
     acceptor: Optional[Callable[[int], bool]]
     dlcs: Dict[int, DLC]
 
-    def __init__(self, l2cap_channel: l2cap.Channel, role: int) -> None:
+    def __init__(self, l2cap_channel: l2cap.Channel, role: Role) -> None:
         super().__init__()
         self.role = role
         self.l2cap_channel = l2cap_channel
-        self.state = Multiplexer.INIT
+        self.state = Multiplexer.State.INIT
         self.dlcs = {}  # DLCs, by DLCI
         self.connection_result = None
         self.disconnection_result = None
@@ -641,14 +688,8 @@ class Multiplexer(EventEmitter):
         # Become a sink for the L2CAP channel
         l2cap_channel.sink = self.on_pdu
 
-    @staticmethod
-    def state_name(state: int):
-        return Multiplexer.STATE_NAMES[state]
-
-    def change_state(self, new_state: int) -> None:
-        logger.debug(
-            f'{self} state change -> {color(self.state_name(new_state), "cyan")}'
-        )
+    def change_state(self, new_state: State) -> None:
+        logger.debug(f'{self} state change -> {color(new_state.name, "cyan")}')
         self.state = new_state
 
     def send_frame(self, frame: RFCOMM_Frame) -> None:
@@ -679,28 +720,28 @@ class Multiplexer(EventEmitter):
         handler = getattr(self, f'on_{frame.type_name()}_frame'.lower())
         handler(frame)
 
-    def on_sabm_frame(self, _frame) -> None:
-        if self.state != Multiplexer.INIT:
+    def on_sabm_frame(self, _frame: RFCOMM_Frame) -> None:
+        if self.state != Multiplexer.State.INIT:
             logger.debug('not in INIT state, ignoring SABM')
             return
-        self.change_state(Multiplexer.CONNECTED)
+        self.change_state(Multiplexer.State.CONNECTED)
         self.send_frame(RFCOMM_Frame.ua(c_r=1, dlci=0))
 
-    def on_ua_frame(self, _frame) -> None:
-        if self.state == Multiplexer.CONNECTING:
-            self.change_state(Multiplexer.CONNECTED)
+    def on_ua_frame(self, _frame: RFCOMM_Frame) -> None:
+        if self.state == Multiplexer.State.CONNECTING:
+            self.change_state(Multiplexer.State.CONNECTED)
             if self.connection_result:
                 self.connection_result.set_result(0)
                 self.connection_result = None
-        elif self.state == Multiplexer.DISCONNECTING:
-            self.change_state(Multiplexer.DISCONNECTED)
+        elif self.state == Multiplexer.State.DISCONNECTING:
+            self.change_state(Multiplexer.State.DISCONNECTED)
             if self.disconnection_result:
                 self.disconnection_result.set_result(None)
                 self.disconnection_result = None
 
-    def on_dm_frame(self, _frame) -> None:
-        if self.state == Multiplexer.OPENING:
-            self.change_state(Multiplexer.CONNECTED)
+    def on_dm_frame(self, _frame: RFCOMM_Frame) -> None:
+        if self.state == Multiplexer.State.OPENING:
+            self.change_state(Multiplexer.State.CONNECTED)
             if self.open_result:
                 self.open_result.set_exception(
                     core.ConnectionError(
@@ -713,10 +754,12 @@ class Multiplexer(EventEmitter):
         else:
             logger.warning(f'unexpected state for DM: {self}')
 
-    def on_disc_frame(self, _frame) -> None:
-        self.change_state(Multiplexer.DISCONNECTED)
+    def on_disc_frame(self, _frame: RFCOMM_Frame) -> None:
+        self.change_state(Multiplexer.State.DISCONNECTED)
         self.send_frame(
-            RFCOMM_Frame.ua(c_r=0 if self.role == Multiplexer.INITIATOR else 1, dlci=0)
+            RFCOMM_Frame.ua(
+                c_r=0 if self.role == Multiplexer.Role.INITIATOR else 1, dlci=0
+            )
         )
 
     def on_uih_frame(self, frame: RFCOMM_Frame) -> None:
@@ -729,11 +772,11 @@ class Multiplexer(EventEmitter):
             mcs = RFCOMM_MCC_MSC.from_bytes(value)
             self.on_mcc_msc(c_r, mcs)
 
-    def on_ui_frame(self, frame) -> None:
+    def on_ui_frame(self, frame: RFCOMM_Frame) -> None:
         pass
 
-    def on_mcc_pn(self, c_r, pn) -> None:
-        if c_r == 1:
+    def on_mcc_pn(self, c_r: bool, pn: RFCOMM_MCC_PN) -> None:
+        if c_r:
             # Command
             logger.debug(f'<<< PN Command: {pn}')
 
@@ -764,14 +807,14 @@ class Multiplexer(EventEmitter):
         else:
             # Response
             logger.debug(f'>>> PN Response: {pn}')
-            if self.state == Multiplexer.OPENING:
+            if self.state == Multiplexer.State.OPENING:
                 dlc = DLC(self, pn.dlci, pn.max_frame_size, pn.window_size)
                 self.dlcs[pn.dlci] = dlc
                 dlc.connect()
             else:
                 logger.warning('ignoring PN response')
 
-    def on_mcc_msc(self, c_r, msc) -> None:
+    def on_mcc_msc(self, c_r: bool, msc: RFCOMM_MCC_MSC) -> None:
         dlc = self.dlcs.get(msc.dlci)
         if dlc is None:
             logger.warning(f'no dlc for DLCI {msc.dlci}')
@@ -779,30 +822,30 @@ class Multiplexer(EventEmitter):
         dlc.on_mcc_msc(c_r, msc)
 
     async def connect(self) -> None:
-        if self.state != Multiplexer.INIT:
+        if self.state != Multiplexer.State.INIT:
             raise InvalidStateError('invalid state')
 
-        self.change_state(Multiplexer.CONNECTING)
+        self.change_state(Multiplexer.State.CONNECTING)
         self.connection_result = asyncio.get_running_loop().create_future()
         self.send_frame(RFCOMM_Frame.sabm(c_r=1, dlci=0))
         return await self.connection_result
 
     async def disconnect(self) -> None:
-        if self.state != Multiplexer.CONNECTED:
+        if self.state != Multiplexer.State.CONNECTED:
             return
 
         self.disconnection_result = asyncio.get_running_loop().create_future()
-        self.change_state(Multiplexer.DISCONNECTING)
+        self.change_state(Multiplexer.State.DISCONNECTING)
         self.send_frame(
             RFCOMM_Frame.disc(
-                c_r=1 if self.role == Multiplexer.INITIATOR else 0, dlci=0
+                c_r=1 if self.role == Multiplexer.Role.INITIATOR else 0, dlci=0
             )
         )
         await self.disconnection_result
 
     async def open_dlc(self, channel: int) -> DLC:
-        if self.state != Multiplexer.CONNECTED:
-            if self.state == Multiplexer.OPENING:
+        if self.state != Multiplexer.State.CONNECTED:
+            if self.state == Multiplexer.State.OPENING:
                 raise InvalidStateError('open already in progress')
 
             raise InvalidStateError('not connected')
@@ -819,10 +862,10 @@ class Multiplexer(EventEmitter):
         mcc = RFCOMM_Frame.make_mcc(mcc_type=RFCOMM_MCC_PN_TYPE, c_r=1, data=bytes(pn))
         logger.debug(f'>>> Sending MCC: {pn}')
         self.open_result = asyncio.get_running_loop().create_future()
-        self.change_state(Multiplexer.OPENING)
+        self.change_state(Multiplexer.State.OPENING)
         self.send_frame(
             RFCOMM_Frame.uih(
-                c_r=1 if self.role == Multiplexer.INITIATOR else 0,
+                c_r=1 if self.role == Multiplexer.Role.INITIATOR else 0,
                 dlci=0,
                 information=mcc,
             )
@@ -831,14 +874,14 @@ class Multiplexer(EventEmitter):
         self.open_result = None
         return result
 
-    def on_dlc_open_complete(self, dlc: DLC):
+    def on_dlc_open_complete(self, dlc: DLC) -> None:
         logger.debug(f'DLC [{dlc.dlci}] open complete')
-        self.change_state(Multiplexer.CONNECTED)
+        self.change_state(Multiplexer.State.CONNECTED)
         if self.open_result:
             self.open_result.set_result(dlc)
 
-    def __str__(self):
-        return f'Multiplexer(state={self.state_name(self.state)})'
+    def __str__(self) -> str:
+        return f'Multiplexer(state={self.state.name})'
 
 
 # -----------------------------------------------------------------------------
@@ -846,7 +889,7 @@ class Client:
     multiplexer: Optional[Multiplexer]
     l2cap_channel: Optional[l2cap.Channel]
 
-    def __init__(self, device, connection) -> None:
+    def __init__(self, device: Device, connection: Connection) -> None:
         self.device = device
         self.connection = connection
         self.l2cap_channel = None
@@ -864,7 +907,7 @@ class Client:
 
         assert self.l2cap_channel is not None
         # Create a mutliplexer to manage DLCs with the server
-        self.multiplexer = Multiplexer(self.l2cap_channel, Multiplexer.INITIATOR)
+        self.multiplexer = Multiplexer(self.l2cap_channel, Multiplexer.Role.INITIATOR)
 
         # Connect the multiplexer
         await self.multiplexer.connect()
@@ -886,7 +929,7 @@ class Client:
 class Server(EventEmitter):
     acceptors: Dict[int, Callable[[DLC], None]]
 
-    def __init__(self, device) -> None:
+    def __init__(self, device: Device) -> None:
         super().__init__()
         self.device = device
         self.multiplexer = None
@@ -925,7 +968,7 @@ class Server(EventEmitter):
         logger.debug(f'$$$ L2CAP channel open: {l2cap_channel}')
 
         # Create a new multiplexer for the channel
-        multiplexer = Multiplexer(l2cap_channel, Multiplexer.RESPONDER)
+        multiplexer = Multiplexer(l2cap_channel, Multiplexer.Role.RESPONDER)
         multiplexer.acceptor = self.accept_dlc
         multiplexer.on('dlc', self.on_dlc)
 
diff --git a/bumble/sdp.py b/bumble/sdp.py
index 1d4faf9..6428187 100644
--- a/bumble/sdp.py
+++ b/bumble/sdp.py
@@ -18,13 +18,16 @@
 from __future__ import annotations
 import logging
 import struct
-from typing import Dict, List, Type
+from typing import Dict, List, Type, Optional, Tuple, Union, NewType, TYPE_CHECKING
 
-from . import core
+from . import core, l2cap
 from .colors import color
 from .core import InvalidStateError
 from .hci import HCI_Object, name_or_number, key_with_value
 
+if TYPE_CHECKING:
+    from .device import Device, Connection
+
 # -----------------------------------------------------------------------------
 # Logging
 # -----------------------------------------------------------------------------
@@ -466,7 +469,7 @@ class ServiceAttribute:
         self.value = value
 
     @staticmethod
-    def list_from_data_elements(elements):
+    def list_from_data_elements(elements: List[DataElement]) -> List[ServiceAttribute]:
         attribute_list = []
         for i in range(0, len(elements) // 2):
             attribute_id, attribute_value = elements[2 * i : 2 * (i + 1)]
@@ -478,7 +481,9 @@ class ServiceAttribute:
         return attribute_list
 
     @staticmethod
-    def find_attribute_in_list(attribute_list, attribute_id):
+    def find_attribute_in_list(
+        attribute_list: List[ServiceAttribute], attribute_id: int
+    ) -> Optional[DataElement]:
         return next(
             (
                 attribute.value
@@ -493,7 +498,7 @@ class ServiceAttribute:
         return name_or_number(SDP_ATTRIBUTE_ID_NAMES, id_code)
 
     @staticmethod
-    def is_uuid_in_value(uuid, value):
+    def is_uuid_in_value(uuid: core.UUID, value: DataElement) -> bool:
         # Find if a uuid matches a value, either directly or recursing into sequences
         if value.type == DataElement.UUID:
             return value.value == uuid
@@ -547,7 +552,9 @@ class SDP_PDU:
         return self
 
     @staticmethod
-    def parse_service_record_handle_list_preceded_by_count(data, offset):
+    def parse_service_record_handle_list_preceded_by_count(
+        data: bytes, offset: int
+    ) -> Tuple[int, List[int]]:
         count = struct.unpack_from('>H', data, offset - 2)[0]
         handle_list = [
             struct.unpack_from('>I', data, offset + x * 4)[0] for x in range(count)
@@ -645,6 +652,10 @@ class SDP_ServiceSearchRequest(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.5.1 SDP_ServiceSearchRequest PDU
     '''
 
+    service_search_pattern: DataElement
+    maximum_service_record_count: int
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 @SDP_PDU.subclass(
@@ -663,6 +674,11 @@ class SDP_ServiceSearchResponse(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.5.2 SDP_ServiceSearchResponse PDU
     '''
 
+    service_record_handle_list: List[int]
+    total_service_record_count: int
+    current_service_record_count: int
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 @SDP_PDU.subclass(
@@ -678,6 +694,11 @@ class SDP_ServiceAttributeRequest(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.6.1 SDP_ServiceAttributeRequest PDU
     '''
 
+    service_record_handle: int
+    maximum_attribute_byte_count: int
+    attribute_id_list: DataElement
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 @SDP_PDU.subclass(
@@ -692,6 +713,10 @@ class SDP_ServiceAttributeResponse(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.6.2 SDP_ServiceAttributeResponse PDU
     '''
 
+    attribute_list_byte_count: int
+    attribute_list: bytes
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 @SDP_PDU.subclass(
@@ -707,6 +732,11 @@ class SDP_ServiceSearchAttributeRequest(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.7.1 SDP_ServiceSearchAttributeRequest PDU
     '''
 
+    service_search_pattern: DataElement
+    maximum_attribute_byte_count: int
+    attribute_id_list: DataElement
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 @SDP_PDU.subclass(
@@ -721,26 +751,34 @@ class SDP_ServiceSearchAttributeResponse(SDP_PDU):
     See Bluetooth spec @ Vol 3, Part B - 4.7.2 SDP_ServiceSearchAttributeResponse PDU
     '''
 
+    attribute_list_byte_count: int
+    attribute_list: bytes
+    continuation_state: bytes
+
 
 # -----------------------------------------------------------------------------
 class Client:
-    def __init__(self, device):
+    channel: Optional[l2cap.Channel]
+
+    def __init__(self, device: Device) -> None:
         self.device = device
         self.pending_request = None
         self.channel = None
 
-    async def connect(self, connection):
+    async def connect(self, connection: Connection) -> None:
         result = await self.device.l2cap_channel_manager.connect(connection, SDP_PSM)
         self.channel = result
 
-    async def disconnect(self):
+    async def disconnect(self) -> None:
         if self.channel:
             await self.channel.disconnect()
             self.channel = None
 
-    async def search_services(self, uuids):
+    async def search_services(self, uuids: List[core.UUID]) -> List[int]:
         if self.pending_request is not None:
             raise InvalidStateError('request already pending')
+        if self.channel is None:
+            raise InvalidStateError('L2CAP not connected')
 
         service_search_pattern = DataElement.sequence(
             [DataElement.uuid(uuid) for uuid in uuids]
@@ -770,9 +808,13 @@ class Client:
 
         return service_record_handle_list
 
-    async def search_attributes(self, uuids, attribute_ids):
+    async def search_attributes(
+        self, uuids: List[core.UUID], attribute_ids: List[Union[int, Tuple[int, int]]]
+    ) -> List[List[ServiceAttribute]]:
         if self.pending_request is not None:
             raise InvalidStateError('request already pending')
+        if self.channel is None:
+            raise InvalidStateError('L2CAP not connected')
 
         service_search_pattern = DataElement.sequence(
             [DataElement.uuid(uuid) for uuid in uuids]
@@ -823,9 +865,15 @@ class Client:
             if sequence.type == DataElement.SEQUENCE
         ]
 
-    async def get_attributes(self, service_record_handle, attribute_ids):
+    async def get_attributes(
+        self,
+        service_record_handle: int,
+        attribute_ids: List[Union[int, Tuple[int, int]]],
+    ) -> List[ServiceAttribute]:
         if self.pending_request is not None:
             raise InvalidStateError('request already pending')
+        if self.channel is None:
+            raise InvalidStateError('L2CAP not connected')
 
         attribute_id_list = DataElement.sequence(
             [
@@ -873,21 +921,25 @@ class Client:
 # -----------------------------------------------------------------------------
 class Server:
     CONTINUATION_STATE = bytes([0x01, 0x43])
+    channel: Optional[l2cap.Channel]
+    Service = NewType('Service', List[ServiceAttribute])
+    service_records: Dict[int, Service]
+    current_response: Union[None, bytes, Tuple[int, List[int]]]
 
-    def __init__(self, device):
+    def __init__(self, device: Device) -> None:
         self.device = device
         self.service_records = {}  # Service records maps, by record handle
         self.channel = None
         self.current_response = None
 
-    def register(self, l2cap_channel_manager):
+    def register(self, l2cap_channel_manager: l2cap.ChannelManager) -> None:
         l2cap_channel_manager.register_server(SDP_PSM, self.on_connection)
 
     def send_response(self, response):
         logger.debug(f'{color(">>> Sending SDP Response", "blue")}: {response}')
         self.channel.send_pdu(response)
 
-    def match_services(self, search_pattern):
+    def match_services(self, search_pattern: DataElement) -> Dict[int, Service]:
         # Find the services for which the attributes in the pattern is a subset of the
         # service's attribute values (NOTE: the value search recurses into sequences)
         matching_services = {}
@@ -957,7 +1009,9 @@ class Server:
         return (payload, continuation_state)
 
     @staticmethod
-    def get_service_attributes(service, attribute_ids):
+    def get_service_attributes(
+        service: Service, attribute_ids: List[DataElement]
+    ) -> DataElement:
         attributes = []
         for attribute_id in attribute_ids:
             if attribute_id.value_size == 4:
@@ -982,10 +1036,10 @@ class Server:
 
         return attribute_list
 
-    def on_sdp_service_search_request(self, request):
+    def on_sdp_service_search_request(self, request: SDP_ServiceSearchRequest) -> None:
         # Check if this is a continuation
         if len(request.continuation_state) > 1:
-            if not self.current_response:
+            if self.current_response is None:
                 self.send_response(
                     SDP_ErrorResponse(
                         transaction_id=request.transaction_id,
@@ -1014,6 +1068,7 @@ class Server:
             )
 
         # Respond, keeping any unsent handles for later
+        assert isinstance(self.current_response, tuple)
         service_record_handles = self.current_response[1][
             : request.maximum_service_record_count
         ]
@@ -1037,10 +1092,12 @@ class Server:
             )
         )
 
-    def on_sdp_service_attribute_request(self, request):
+    def on_sdp_service_attribute_request(
+        self, request: SDP_ServiceAttributeRequest
+    ) -> None:
         # Check if this is a continuation
         if len(request.continuation_state) > 1:
-            if not self.current_response:
+            if self.current_response is None:
                 self.send_response(
                     SDP_ErrorResponse(
                         transaction_id=request.transaction_id,
@@ -1073,22 +1130,24 @@ class Server:
             self.current_response = bytes(attribute_list)
 
         # Respond, keeping any pending chunks for later
-        attribute_list, continuation_state = self.get_next_response_payload(
+        attribute_list_response, continuation_state = self.get_next_response_payload(
             request.maximum_attribute_byte_count
         )
         self.send_response(
             SDP_ServiceAttributeResponse(
                 transaction_id=request.transaction_id,
-                attribute_list_byte_count=len(attribute_list),
+                attribute_list_byte_count=len(attribute_list_response),
                 attribute_list=attribute_list,
                 continuation_state=continuation_state,
             )
         )
 
-    def on_sdp_service_search_attribute_request(self, request):
+    def on_sdp_service_search_attribute_request(
+        self, request: SDP_ServiceSearchAttributeRequest
+    ) -> None:
         # Check if this is a continuation
         if len(request.continuation_state) > 1:
-            if not self.current_response:
+            if self.current_response is None:
                 self.send_response(
                     SDP_ErrorResponse(
                         transaction_id=request.transaction_id,
@@ -1118,13 +1177,13 @@ class Server:
             self.current_response = bytes(attribute_lists)
 
         # Respond, keeping any pending chunks for later
-        attribute_lists, continuation_state = self.get_next_response_payload(
+        attribute_lists_response, continuation_state = self.get_next_response_payload(
             request.maximum_attribute_byte_count
         )
         self.send_response(
             SDP_ServiceSearchAttributeResponse(
                 transaction_id=request.transaction_id,
-                attribute_lists_byte_count=len(attribute_lists),
+                attribute_lists_byte_count=len(attribute_lists_response),
                 attribute_lists=attribute_lists,
                 continuation_state=continuation_state,
             )
diff --git a/bumble/smp.py b/bumble/smp.py
index 9588a5a..f8bba40 100644
--- a/bumble/smp.py
+++ b/bumble/smp.py
@@ -37,6 +37,7 @@ from typing import (
     Optional,
     Tuple,
     Type,
+    cast,
 )
 
 from pyee import EventEmitter
@@ -1771,7 +1772,26 @@ class Manager(EventEmitter):
         cid = SMP_BR_CID if connection.transport == BT_BR_EDR_TRANSPORT else SMP_CID
         connection.send_l2cap_pdu(cid, command.to_bytes())
 
+    def on_smp_security_request_command(
+        self, connection: Connection, request: SMP_Security_Request_Command
+    ) -> None:
+        connection.emit('security_request', request.auth_req)
+
     def on_smp_pdu(self, connection: Connection, pdu: bytes) -> None:
+        # Parse the L2CAP payload into an SMP Command object
+        command = SMP_Command.from_bytes(pdu)
+        logger.debug(
+            f'<<< Received SMP Command on connection [0x{connection.handle:04X}] '
+            f'{connection.peer_address}: {command}'
+        )
+
+        # Security request is more than just pairing, so let applications handle them
+        if command.code == SMP_SECURITY_REQUEST_COMMAND:
+            self.on_smp_security_request_command(
+                connection, cast(SMP_Security_Request_Command, command)
+            )
+            return
+
         # Look for a session with this connection, and create one if none exists
         if not (session := self.sessions.get(connection.handle)):
             if connection.role == BT_CENTRAL_ROLE:
@@ -1782,13 +1802,6 @@ class Manager(EventEmitter):
             )
             self.sessions[connection.handle] = session
 
-        # Parse the L2CAP payload into an SMP Command object
-        command = SMP_Command.from_bytes(pdu)
-        logger.debug(
-            f'<<< Received SMP Command on connection [0x{connection.handle:04X}] '
-            f'{connection.peer_address}: {command}'
-        )
-
         # Delegate the handling of the command to the session
         session.on_smp_command(command)
 
@@ -1832,8 +1845,9 @@ class Manager(EventEmitter):
     ) -> None:
         # Store the keys in the key store
         if self.device.keystore and identity_address is not None:
-            await self.device.keystore.update(str(identity_address), keys)
-            await self.device.refresh_resolving_list()
+            self.device.abort_on(
+                'flush', self.device.update_keys(str(identity_address), keys)
+            )
 
         # Notify the device
         self.device.on_pairing(session.connection, identity_address, keys, session.sc)
diff --git a/bumble/transport/__init__.py b/bumble/transport/__init__.py
index 840b3e5..bc0766b 100644
--- a/bumble/transport/__init__.py
+++ b/bumble/transport/__init__.py
@@ -20,7 +20,6 @@ import logging
 import os
 
 from .common import Transport, AsyncPipeSink, SnoopingTransport
-from ..controller import Controller
 from ..snoop import create_snooper
 
 # -----------------------------------------------------------------------------
@@ -69,6 +68,7 @@ async def open_transport(name: str) -> Transport:
       * usb
       * pyusb
       * android-emulator
+      * android-netsim
     """
 
     return _wrap_transport(await _open_transport(name))
@@ -118,7 +118,8 @@ async def _open_transport(name: str) -> Transport:
     if scheme == 'file':
         from .file import open_file_transport
 
-        return await open_file_transport(spec[0] if spec else None)
+        assert spec is not None
+        return await open_file_transport(spec[0])
 
     if scheme == 'vhci':
         from .vhci import open_vhci_transport
@@ -133,12 +134,14 @@ async def _open_transport(name: str) -> Transport:
     if scheme == 'usb':
         from .usb import open_usb_transport
 
-        return await open_usb_transport(spec[0] if spec else None)
+        assert spec is not None
+        return await open_usb_transport(spec[0])
 
     if scheme == 'pyusb':
         from .pyusb import open_pyusb_transport
 
-        return await open_pyusb_transport(spec[0] if spec else None)
+        assert spec is not None
+        return await open_pyusb_transport(spec[0])
 
     if scheme == 'android-emulator':
         from .android_emulator import open_android_emulator_transport
@@ -167,6 +170,7 @@ async def open_transport_or_link(name: str) -> Transport:
 
     """
     if name.startswith('link-relay:'):
+        from ..controller import Controller
         from ..link import RemoteLink  # lazy import
 
         link = RemoteLink(name[11:])
diff --git a/bumble/transport/android_emulator.py b/bumble/transport/android_emulator.py
index b78e263..8d19a9e 100644
--- a/bumble/transport/android_emulator.py
+++ b/bumble/transport/android_emulator.py
@@ -18,7 +18,9 @@
 import logging
 import grpc.aio
 
-from .common import PumpedTransport, PumpedPacketSource, PumpedPacketSink
+from typing import Optional, Union
+
+from .common import PumpedTransport, PumpedPacketSource, PumpedPacketSink, Transport
 
 # pylint: disable=no-name-in-module
 from .grpc_protobuf.emulated_bluetooth_pb2_grpc import EmulatedBluetoothServiceStub
@@ -33,7 +35,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_android_emulator_transport(spec):
+async def open_android_emulator_transport(spec: Optional[str]) -> Transport:
     '''
     Open a transport connection to an Android emulator via its gRPC interface.
     The parameter string has this syntax:
@@ -66,7 +68,7 @@ async def open_android_emulator_transport(spec):
     # Parse the parameters
     mode = 'host'
     server_host = 'localhost'
-    server_port = 8554
+    server_port = '8554'
     if spec is not None:
         params = spec.split(',')
         for param in params:
@@ -82,6 +84,7 @@ async def open_android_emulator_transport(spec):
     logger.debug(f'connecting to gRPC server at {server_address}')
     channel = grpc.aio.insecure_channel(server_address)
 
+    service: Union[EmulatedBluetoothServiceStub, VhciForwardingServiceStub]
     if mode == 'host':
         # Connect as a host
         service = EmulatedBluetoothServiceStub(channel)
@@ -94,10 +97,13 @@ async def open_android_emulator_transport(spec):
         raise ValueError('invalid mode')
 
     # Create the transport object
-    transport = PumpedTransport(
-        PumpedPacketSource(hci_device.read),
-        PumpedPacketSink(hci_device.write),
-        channel.close,
+    class EmulatorTransport(PumpedTransport):
+        async def close(self):
+            await super().close()
+            await channel.close()
+
+    transport = EmulatorTransport(
+        PumpedPacketSource(hci_device.read), PumpedPacketSink(hci_device.write)
     )
     transport.start()
 
diff --git a/bumble/transport/android_netsim.py b/bumble/transport/android_netsim.py
index 99ebf87..e9d36cd 100644
--- a/bumble/transport/android_netsim.py
+++ b/bumble/transport/android_netsim.py
@@ -18,11 +18,12 @@
 import asyncio
 import atexit
 import logging
-import grpc.aio
 import os
 import pathlib
 import sys
-from typing import Optional
+from typing import Dict, Optional
+
+import grpc.aio
 
 from .common import (
     ParserSource,
@@ -33,8 +34,8 @@ from .common import (
 )
 
 # pylint: disable=no-name-in-module
-from .grpc_protobuf.packet_streamer_pb2_grpc import PacketStreamerStub
 from .grpc_protobuf.packet_streamer_pb2_grpc import (
+    PacketStreamerStub,
     PacketStreamerServicer,
     add_PacketStreamerServicer_to_server,
 )
@@ -43,6 +44,7 @@ from .grpc_protobuf.hci_packet_pb2 import HCIPacket
 from .grpc_protobuf.startup_pb2 import Chip, ChipInfo
 from .grpc_protobuf.common_pb2 import ChipKind
 
+
 # -----------------------------------------------------------------------------
 # Logging
 # -----------------------------------------------------------------------------
@@ -74,14 +76,20 @@ def get_ini_dir() -> Optional[pathlib.Path]:
 
 
 # -----------------------------------------------------------------------------
-def find_grpc_port() -> int:
+def ini_file_name(instance_number: int) -> str:
+    suffix = f'_{instance_number}' if instance_number > 0 else ''
+    return f'netsim{suffix}.ini'
+
+
+# -----------------------------------------------------------------------------
+def find_grpc_port(instance_number: int) -> int:
     if not (ini_dir := get_ini_dir()):
         logger.debug('no known directory for .ini file')
         return 0
 
-    ini_file = ini_dir / 'netsim.ini'
+    ini_file = ini_dir / ini_file_name(instance_number)
+    logger.debug(f'Looking for .ini file at {ini_file}')
     if ini_file.is_file():
-        logger.debug(f'Found .ini file at {ini_file}')
         with open(ini_file, 'r') as ini_file_data:
             for line in ini_file_data.readlines():
                 if '=' in line:
@@ -90,12 +98,14 @@ def find_grpc_port() -> int:
                         logger.debug(f'gRPC port = {value}')
                         return int(value)
 
+        logger.debug('no grpc.port property found in .ini file')
+
     # Not found
     return 0
 
 
 # -----------------------------------------------------------------------------
-def publish_grpc_port(grpc_port) -> bool:
+def publish_grpc_port(grpc_port: int, instance_number: int) -> bool:
     if not (ini_dir := get_ini_dir()):
         logger.debug('no known directory for .ini file')
         return False
@@ -104,7 +114,7 @@ def publish_grpc_port(grpc_port) -> bool:
         logger.debug('ini directory does not exist')
         return False
 
-    ini_file = ini_dir / 'netsim.ini'
+    ini_file = ini_dir / ini_file_name(instance_number)
     try:
         ini_file.write_text(f'grpc.port={grpc_port}\n')
         logger.debug(f"published gRPC port at {ini_file}")
@@ -121,13 +131,16 @@ def publish_grpc_port(grpc_port) -> bool:
 
 
 # -----------------------------------------------------------------------------
-async def open_android_netsim_controller_transport(server_host, server_port):
+async def open_android_netsim_controller_transport(
+    server_host: Optional[str], server_port: int, options: Dict[str, str]
+) -> Transport:
     if not server_port:
         raise ValueError('invalid port')
     if server_host == '_' or not server_host:
         server_host = 'localhost'
 
-    if not publish_grpc_port(server_port):
+    instance_number = int(options.get('instance', "0"))
+    if not publish_grpc_port(server_port, instance_number):
         logger.warning("unable to publish gRPC port")
 
     class HciDevice:
@@ -184,15 +197,12 @@ async def open_android_netsim_controller_transport(server_host, server_port):
                 logger.debug(f'<<< PACKET: {data.hex()}')
                 self.on_data_received(data)
 
-        def send_packet(self, data):
-            async def send():
-                await self.context.write(
-                    PacketResponse(
-                        hci_packet=HCIPacket(packet_type=data[0], packet=data[1:])
-                    )
+        async def send_packet(self, data):
+            return await self.context.write(
+                PacketResponse(
+                    hci_packet=HCIPacket(packet_type=data[0], packet=data[1:])
                 )
-
-            self.loop.create_task(send())
+            )
 
         def terminate(self):
             self.task.cancel()
@@ -226,17 +236,17 @@ async def open_android_netsim_controller_transport(server_host, server_port):
                 logger.debug('gRPC server cancelled')
                 await self.grpc_server.stop(None)
 
-        def on_packet(self, packet):
+        async def send_packet(self, packet):
             if not self.device:
                 logger.debug('no device, dropping packet')
                 return
 
-            self.device.send_packet(packet)
+            return await self.device.send_packet(packet)
 
         async def StreamPackets(self, _request_iterator, context):
             logger.debug('StreamPackets request')
 
-            # Check that we won't already have a device
+            # Check that we don't already have a device
             if self.device:
                 logger.debug('busy, already serving a device')
                 return PacketResponse(error='Busy')
@@ -259,15 +269,42 @@ async def open_android_netsim_controller_transport(server_host, server_port):
     await server.start()
     asyncio.get_running_loop().create_task(server.serve())
 
-    class GrpcServerTransport(Transport):
-        async def close(self):
-            await super().close()
+    sink = PumpedPacketSink(server.send_packet)
+    sink.start()
+    return Transport(server, sink)
+
+
+# -----------------------------------------------------------------------------
+async def open_android_netsim_host_transport_with_address(
+    server_host: Optional[str],
+    server_port: int,
+    options: Optional[Dict[str, str]] = None,
+):
+    if server_host == '_' or not server_host:
+        server_host = 'localhost'
+
+    if not server_port:
+        # Look for the gRPC config in a .ini file
+        instance_number = 0 if options is None else int(options.get('instance', '0'))
+        server_port = find_grpc_port(instance_number)
+        if not server_port:
+            raise RuntimeError('gRPC server port not found')
+
+    # Connect to the gRPC server
+    server_address = f'{server_host}:{server_port}'
+    logger.debug(f'Connecting to gRPC server at {server_address}')
+    channel = grpc.aio.insecure_channel(server_address)
 
-    return GrpcServerTransport(server, server)
+    return await open_android_netsim_host_transport_with_channel(
+        channel,
+        options,
+    )
 
 
 # -----------------------------------------------------------------------------
-async def open_android_netsim_host_transport(server_host, server_port, options):
+async def open_android_netsim_host_transport_with_channel(
+    channel, options: Optional[Dict[str, str]] = None
+):
     # Wrapper for I/O operations
     class HciDevice:
         def __init__(self, name, manufacturer, hci_device):
@@ -286,10 +323,12 @@ async def open_android_netsim_host_transport(server_host, server_port, options):
         async def read(self):
             response = await self.hci_device.read()
             response_type = response.WhichOneof('response_type')
+
             if response_type == 'error':
                 logger.warning(f'received error: {response.error}')
                 raise RuntimeError(response.error)
-            elif response_type == 'hci_packet':
+
+            if response_type == 'hci_packet':
                 return (
                     bytes([response.hci_packet.packet_type])
                     + response.hci_packet.packet
@@ -304,24 +343,9 @@ async def open_android_netsim_host_transport(server_host, server_port, options):
                 )
             )
 
-    name = options.get('name', DEFAULT_NAME)
+    name = DEFAULT_NAME if options is None else options.get('name', DEFAULT_NAME)
     manufacturer = DEFAULT_MANUFACTURER
 
-    if server_host == '_' or not server_host:
-        server_host = 'localhost'
-
-    if not server_port:
-        # Look for the gRPC config in a .ini file
-        server_host = 'localhost'
-        server_port = find_grpc_port()
-        if not server_port:
-            raise RuntimeError('gRPC server port not found')
-
-    # Connect to the gRPC server
-    server_address = f'{server_host}:{server_port}'
-    logger.debug(f'Connecting to gRPC server at {server_address}')
-    channel = grpc.aio.insecure_channel(server_address)
-
     # Connect as a host
     service = PacketStreamerStub(channel)
     hci_device = HciDevice(
@@ -332,10 +356,14 @@ async def open_android_netsim_host_transport(server_host, server_port, options):
     await hci_device.start()
 
     # Create the transport object
-    transport = PumpedTransport(
+    class GrpcTransport(PumpedTransport):
+        async def close(self):
+            await super().close()
+            await channel.close()
+
+    transport = GrpcTransport(
         PumpedPacketSource(hci_device.read),
         PumpedPacketSink(hci_device.write),
-        channel.close,
     )
     transport.start()
 
@@ -343,7 +371,7 @@ async def open_android_netsim_host_transport(server_host, server_port, options):
 
 
 # -----------------------------------------------------------------------------
-async def open_android_netsim_transport(spec):
+async def open_android_netsim_transport(spec: Optional[str]) -> Transport:
     '''
     Open a transport connection as a client or server, implementing Android's `netsim`
     simulator protocol over gRPC.
@@ -357,6 +385,11 @@ async def open_android_netsim_transport(spec):
         to connect *to* a netsim server (netsim is the controller), or accept
         connections *as* a netsim-compatible server.
 
+      instance=<n>
+        Specifies an instance number, with <n> > 0. This is used to determine which
+        .init file to use. In `host` mode, it is ignored when the <host>:<port>
+        specifier is present, since in that case no .ini file is used.
+
     In `host` mode:
       The <host>:<port> part is optional. When not specified, the transport
       looks for a netsim .ini file, from which it will read the `grpc.backend.port`
@@ -385,14 +418,15 @@ async def open_android_netsim_transport(spec):
     params = spec.split(',') if spec else []
     if params and ':' in params[0]:
         # Explicit <host>:<port>
-        host, port = params[0].split(':')
+        host, port_str = params[0].split(':')
+        port = int(port_str)
         params_offset = 1
     else:
         host = None
         port = 0
         params_offset = 0
 
-    options = {}
+    options: Dict[str, str] = {}
     for param in params[params_offset:]:
         if '=' not in param:
             raise ValueError('invalid parameter, expected <name>=<value>')
@@ -401,10 +435,12 @@ async def open_android_netsim_transport(spec):
 
     mode = options.get('mode', 'host')
     if mode == 'host':
-        return await open_android_netsim_host_transport(host, port, options)
+        return await open_android_netsim_host_transport_with_address(
+            host, port, options
+        )
     if mode == 'controller':
         if host is None:
             raise ValueError('<host>:<port> missing')
-        return await open_android_netsim_controller_transport(host, port)
+        return await open_android_netsim_controller_transport(host, port, options)
 
     raise ValueError('invalid mode option')
diff --git a/bumble/transport/common.py b/bumble/transport/common.py
index 05a1fb5..2786a75 100644
--- a/bumble/transport/common.py
+++ b/bumble/transport/common.py
@@ -20,11 +20,12 @@ import contextlib
 import struct
 import asyncio
 import logging
-from typing import ContextManager
+import io
+from typing import ContextManager, Tuple, Optional, Protocol, Dict
 
-from .. import hci
-from ..colors import color
-from ..snoop import Snooper
+from bumble import hci
+from bumble.colors import color
+from bumble.snoop import Snooper
 
 
 # -----------------------------------------------------------------------------
@@ -36,7 +37,7 @@ logger = logging.getLogger(__name__)
 # Information needed to parse HCI packets with a generic parser:
 # For each packet type, the info represents:
 # (length-size, length-offset, unpack-type)
-HCI_PACKET_INFO = {
+HCI_PACKET_INFO: Dict[int, Tuple[int, int, str]] = {
     hci.HCI_COMMAND_PACKET: (1, 2, 'B'),
     hci.HCI_ACL_DATA_PACKET: (2, 2, 'H'),
     hci.HCI_SYNCHRONOUS_DATA_PACKET: (1, 2, 'B'),
@@ -45,33 +46,54 @@ HCI_PACKET_INFO = {
 
 
 # -----------------------------------------------------------------------------
+# Errors
+# -----------------------------------------------------------------------------
+class TransportLostError(Exception):
+    """
+    The Transport has been lost/disconnected.
+    """
+
+
+# -----------------------------------------------------------------------------
+# Typing Protocols
+# -----------------------------------------------------------------------------
+class TransportSink(Protocol):
+    def on_packet(self, packet: bytes) -> None:
+        ...
+
+
+class TransportSource(Protocol):
+    terminated: asyncio.Future[None]
+
+    def set_packet_sink(self, sink: TransportSink) -> None:
+        ...
+
+
+# -----------------------------------------------------------------------------
 class PacketPump:
-    '''
-    Pump HCI packets from a reader to a sink
-    '''
+    """
+    Pump HCI packets from a reader to a sink.
+    """
 
-    def __init__(self, reader, sink):
+    def __init__(self, reader: AsyncPacketReader, sink: TransportSink) -> None:
         self.reader = reader
         self.sink = sink
 
-    async def run(self):
+    async def run(self) -> None:
         while True:
             try:
-                # Get a packet from the source
-                packet = hci.HCI_Packet.from_bytes(await self.reader.next_packet())
-
                 # Deliver the packet to the sink
-                self.sink.on_packet(packet)
+                self.sink.on_packet(await self.reader.next_packet())
             except Exception as error:
                 logger.warning(f'!!! {error}')
 
 
 # -----------------------------------------------------------------------------
 class PacketParser:
-    '''
+    """
     In-line parser that accepts data and emits 'on_packet' when a full packet has been
-    parsed
-    '''
+    parsed.
+    """
 
     # pylint: disable=attribute-defined-outside-init
 
@@ -79,18 +101,22 @@ class PacketParser:
     NEED_LENGTH = 1
     NEED_BODY = 2
 
-    def __init__(self, sink=None):
+    sink: Optional[TransportSink]
+    extended_packet_info: Dict[int, Tuple[int, int, str]]
+    packet_info: Optional[Tuple[int, int, str]] = None
+
+    def __init__(self, sink: Optional[TransportSink] = None) -> None:
         self.sink = sink
         self.extended_packet_info = {}
         self.reset()
 
-    def reset(self):
+    def reset(self) -> None:
         self.state = PacketParser.NEED_TYPE
         self.bytes_needed = 1
         self.packet = bytearray()
         self.packet_info = None
 
-    def feed_data(self, data):
+    def feed_data(self, data: bytes) -> None:
         data_offset = 0
         data_left = len(data)
         while data_left and self.bytes_needed:
@@ -111,6 +137,7 @@ class PacketParser:
                     self.state = PacketParser.NEED_LENGTH
                     self.bytes_needed = self.packet_info[0] + self.packet_info[1]
                 elif self.state == PacketParser.NEED_LENGTH:
+                    assert self.packet_info is not None
                     body_length = struct.unpack_from(
                         self.packet_info[2], self.packet, 1 + self.packet_info[1]
                     )[0]
@@ -128,20 +155,20 @@ class PacketParser:
                             )
                     self.reset()
 
-    def set_packet_sink(self, sink):
+    def set_packet_sink(self, sink: TransportSink) -> None:
         self.sink = sink
 
 
 # -----------------------------------------------------------------------------
 class PacketReader:
-    '''
-    Reader that reads HCI packets from a sync source
-    '''
+    """
+    Reader that reads HCI packets from a sync source.
+    """
 
-    def __init__(self, source):
+    def __init__(self, source: io.BufferedReader) -> None:
         self.source = source
 
-    def next_packet(self):
+    def next_packet(self) -> Optional[bytes]:
         # Get the packet type
         packet_type = self.source.read(1)
         if len(packet_type) != 1:
@@ -150,7 +177,7 @@ class PacketReader:
         # Get the packet info based on its type
         packet_info = HCI_PACKET_INFO.get(packet_type[0])
         if packet_info is None:
-            raise ValueError(f'invalid packet type {packet_type} found')
+            raise ValueError(f'invalid packet type {packet_type[0]} found')
 
         # Read the header (that includes the length)
         header_size = packet_info[0] + packet_info[1]
@@ -169,21 +196,21 @@ class PacketReader:
 
 # -----------------------------------------------------------------------------
 class AsyncPacketReader:
-    '''
-    Reader that reads HCI packets from an async source
-    '''
+    """
+    Reader that reads HCI packets from an async source.
+    """
 
-    def __init__(self, source):
+    def __init__(self, source: asyncio.StreamReader) -> None:
         self.source = source
 
-    async def next_packet(self):
+    async def next_packet(self) -> bytes:
         # Get the packet type
         packet_type = await self.source.readexactly(1)
 
         # Get the packet info based on its type
         packet_info = HCI_PACKET_INFO.get(packet_type[0])
         if packet_info is None:
-            raise ValueError(f'invalid packet type {packet_type} found')
+            raise ValueError(f'invalid packet type {packet_type[0]} found')
 
         # Read the header (that includes the length)
         header_size = packet_info[0] + packet_info[1]
@@ -198,15 +225,15 @@ class AsyncPacketReader:
 
 # -----------------------------------------------------------------------------
 class AsyncPipeSink:
-    '''
-    Sink that forwards packets asynchronously to another sink
-    '''
+    """
+    Sink that forwards packets asynchronously to another sink.
+    """
 
-    def __init__(self, sink):
+    def __init__(self, sink: TransportSink) -> None:
         self.sink = sink
         self.loop = asyncio.get_running_loop()
 
-    def on_packet(self, packet):
+    def on_packet(self, packet: bytes) -> None:
         self.loop.call_soon(self.sink.on_packet, packet)
 
 
@@ -216,35 +243,48 @@ class ParserSource:
     Base class designed to be subclassed by transport-specific source classes
     """
 
-    def __init__(self):
+    terminated: asyncio.Future[None]
+    parser: PacketParser
+
+    def __init__(self) -> None:
         self.parser = PacketParser()
         self.terminated = asyncio.get_running_loop().create_future()
 
-    def set_packet_sink(self, sink):
+    def set_packet_sink(self, sink: TransportSink) -> None:
         self.parser.set_packet_sink(sink)
 
-    async def wait_for_termination(self):
+    def on_transport_lost(self) -> None:
+        self.terminated.set_result(None)
+        if self.parser.sink:
+            if hasattr(self.parser.sink, 'on_transport_lost'):
+                self.parser.sink.on_transport_lost()
+
+    async def wait_for_termination(self) -> None:
+        """
+        Convenience method for backward compatibility. Prefer using the `terminated`
+        attribute instead.
+        """
         return await self.terminated
 
-    def close(self):
+    def close(self) -> None:
         pass
 
 
 # -----------------------------------------------------------------------------
 class StreamPacketSource(asyncio.Protocol, ParserSource):
-    def data_received(self, data):
+    def data_received(self, data: bytes) -> None:
         self.parser.feed_data(data)
 
 
 # -----------------------------------------------------------------------------
 class StreamPacketSink:
-    def __init__(self, transport):
+    def __init__(self, transport: asyncio.WriteTransport) -> None:
         self.transport = transport
 
-    def on_packet(self, packet):
+    def on_packet(self, packet: bytes) -> None:
         self.transport.write(packet)
 
-    def close(self):
+    def close(self) -> None:
         self.transport.close()
 
 
@@ -264,7 +304,7 @@ class Transport:
         ...
     """
 
-    def __init__(self, source, sink):
+    def __init__(self, source: TransportSource, sink: TransportSink) -> None:
         self.source = source
         self.sink = sink
 
@@ -278,34 +318,39 @@ class Transport:
         return iter((self.source, self.sink))
 
     async def close(self) -> None:
-        self.source.close()
-        self.sink.close()
+        if hasattr(self.source, 'close'):
+            self.source.close()
+        if hasattr(self.sink, 'close'):
+            self.sink.close()
 
 
 # -----------------------------------------------------------------------------
 class PumpedPacketSource(ParserSource):
-    def __init__(self, receive):
+    pump_task: Optional[asyncio.Task[None]]
+
+    def __init__(self, receive) -> None:
         super().__init__()
         self.receive_function = receive
         self.pump_task = None
 
-    def start(self):
-        async def pump_packets():
+    def start(self) -> None:
+        async def pump_packets() -> None:
             while True:
                 try:
                     packet = await self.receive_function()
                     self.parser.feed_data(packet)
-                except asyncio.exceptions.CancelledError:
+                except asyncio.CancelledError:
                     logger.debug('source pump task done')
+                    self.terminated.set_result(None)
                     break
                 except Exception as error:
                     logger.warning(f'exception while waiting for packet: {error}')
-                    self.terminated.set_result(error)
+                    self.terminated.set_exception(error)
                     break
 
         self.pump_task = asyncio.create_task(pump_packets())
 
-    def close(self):
+    def close(self) -> None:
         if self.pump_task:
             self.pump_task.cancel()
 
@@ -317,7 +362,7 @@ class PumpedPacketSink:
         self.packet_queue = asyncio.Queue()
         self.pump_task = None
 
-    def on_packet(self, packet):
+    def on_packet(self, packet: bytes) -> None:
         self.packet_queue.put_nowait(packet)
 
     def start(self):
@@ -326,7 +371,7 @@ class PumpedPacketSink:
                 try:
                     packet = await self.packet_queue.get()
                     await self.send_function(packet)
-                except asyncio.exceptions.CancelledError:
+                except asyncio.CancelledError:
                     logger.debug('sink pump task done')
                     break
                 except Exception as error:
@@ -342,18 +387,20 @@ class PumpedPacketSink:
 
 # -----------------------------------------------------------------------------
 class PumpedTransport(Transport):
-    def __init__(self, source, sink, close_function):
+    source: PumpedPacketSource
+    sink: PumpedPacketSink
+
+    def __init__(
+        self,
+        source: PumpedPacketSource,
+        sink: PumpedPacketSink,
+    ) -> None:
         super().__init__(source, sink)
-        self.close_function = close_function
 
-    def start(self):
+    def start(self) -> None:
         self.source.start()
         self.sink.start()
 
-    async def close(self):
-        await super().close()
-        await self.close_function()
-
 
 # -----------------------------------------------------------------------------
 class SnoopingTransport(Transport):
@@ -375,31 +422,38 @@ class SnoopingTransport(Transport):
         raise RuntimeError('unexpected code path')  # Satisfy the type checker
 
     class Source:
-        def __init__(self, source, snooper):
+        sink: TransportSink
+
+        def __init__(self, source: TransportSource, snooper: Snooper):
             self.source = source
             self.snooper = snooper
-            self.sink = None
+            self.terminated = source.terminated
 
-        def set_packet_sink(self, sink):
+        def set_packet_sink(self, sink: TransportSink) -> None:
             self.sink = sink
             self.source.set_packet_sink(self)
 
-        def on_packet(self, packet):
+        def on_packet(self, packet: bytes) -> None:
             self.snooper.snoop(packet, Snooper.Direction.CONTROLLER_TO_HOST)
             if self.sink:
                 self.sink.on_packet(packet)
 
     class Sink:
-        def __init__(self, sink, snooper):
+        def __init__(self, sink: TransportSink, snooper: Snooper) -> None:
             self.sink = sink
             self.snooper = snooper
 
-        def on_packet(self, packet):
+        def on_packet(self, packet: bytes) -> None:
             self.snooper.snoop(packet, Snooper.Direction.HOST_TO_CONTROLLER)
             if self.sink:
                 self.sink.on_packet(packet)
 
-    def __init__(self, transport, snooper, close_snooper=None):
+    def __init__(
+        self,
+        transport: Transport,
+        snooper: Snooper,
+        close_snooper=None,
+    ) -> None:
         super().__init__(
             self.Source(transport.source, snooper), self.Sink(transport.sink, snooper)
         )
diff --git a/bumble/transport/file.py b/bumble/transport/file.py
index 9c073d2..dee1c23 100644
--- a/bumble/transport/file.py
+++ b/bumble/transport/file.py
@@ -28,7 +28,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_file_transport(spec):
+async def open_file_transport(spec: str) -> Transport:
     '''
     Open a File transport (typically not for a real file, but for a PTY or other unix
     virtual files).
diff --git a/bumble/transport/hci_socket.py b/bumble/transport/hci_socket.py
index 4e1ad99..df9e885 100644
--- a/bumble/transport/hci_socket.py
+++ b/bumble/transport/hci_socket.py
@@ -23,6 +23,8 @@ import socket
 import ctypes
 import collections
 
+from typing import Optional
+
 from .common import Transport, ParserSource
 
 
@@ -33,7 +35,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_hci_socket_transport(spec):
+async def open_hci_socket_transport(spec: Optional[str]) -> Transport:
     '''
     Open an HCI Socket (only available on some platforms).
     The parameter string is either empty (to use the first/default Bluetooth adapter)
@@ -45,9 +47,9 @@ async def open_hci_socket_transport(spec):
     # Create a raw HCI socket
     try:
         hci_socket = socket.socket(
-            socket.AF_BLUETOOTH,
-            socket.SOCK_RAW | socket.SOCK_NONBLOCK,
-            socket.BTPROTO_HCI,
+            socket.AF_BLUETOOTH,  # type: ignore[attr-defined]
+            socket.SOCK_RAW | socket.SOCK_NONBLOCK,  # type: ignore[attr-defined]
+            socket.BTPROTO_HCI,  # type: ignore[attr-defined]
         )
     except AttributeError as error:
         # Not supported on this platform
@@ -78,7 +80,7 @@ async def open_hci_socket_transport(spec):
     bind_address = struct.pack(
         # pylint: disable=no-member
         '<HHH',
-        socket.AF_BLUETOOTH,
+        socket.AF_BLUETOOTH,  # type: ignore[attr-defined]
         adapter_index,
         HCI_CHANNEL_USER,
     )
diff --git a/bumble/transport/pty.py b/bumble/transport/pty.py
index e6e2ab5..2f46e75 100644
--- a/bumble/transport/pty.py
+++ b/bumble/transport/pty.py
@@ -23,6 +23,8 @@ import atexit
 import os
 import logging
 
+from typing import Optional
+
 from .common import Transport, StreamPacketSource, StreamPacketSink
 
 # -----------------------------------------------------------------------------
@@ -32,7 +34,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_pty_transport(spec):
+async def open_pty_transport(spec: Optional[str]) -> Transport:
     '''
     Open a PTY transport.
     The parameter string may be empty, or a path name where a symbolic link
diff --git a/bumble/transport/pyusb.py b/bumble/transport/pyusb.py
index 8ad8598..5e686d1 100644
--- a/bumble/transport/pyusb.py
+++ b/bumble/transport/pyusb.py
@@ -35,7 +35,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_pyusb_transport(spec):
+async def open_pyusb_transport(spec: str) -> Transport:
     '''
     Open a USB transport. [Implementation based on PyUSB]
     The parameter string has this syntax:
diff --git a/bumble/transport/serial.py b/bumble/transport/serial.py
index c83b605..c48cdc6 100644
--- a/bumble/transport/serial.py
+++ b/bumble/transport/serial.py
@@ -28,7 +28,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_serial_transport(spec):
+async def open_serial_transport(spec: str) -> Transport:
     '''
     Open a serial port transport.
     The parameter string has this syntax:
diff --git a/bumble/transport/tcp_client.py b/bumble/transport/tcp_client.py
index 934a521..4fb268a 100644
--- a/bumble/transport/tcp_client.py
+++ b/bumble/transport/tcp_client.py
@@ -27,7 +27,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_tcp_client_transport(spec):
+async def open_tcp_client_transport(spec: str) -> Transport:
     '''
     Open a TCP client transport.
     The parameter string has this syntax:
@@ -39,7 +39,7 @@ async def open_tcp_client_transport(spec):
     class TcpPacketSource(StreamPacketSource):
         def connection_lost(self, exc):
             logger.debug(f'connection lost: {exc}')
-            self.terminated.set_result(exc)
+            self.on_transport_lost()
 
     remote_host, remote_port = spec.split(':')
     tcp_transport, packet_source = await asyncio.get_running_loop().create_connection(
diff --git a/bumble/transport/tcp_server.py b/bumble/transport/tcp_server.py
index 11b0453..77d0304 100644
--- a/bumble/transport/tcp_server.py
+++ b/bumble/transport/tcp_server.py
@@ -15,6 +15,7 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
 import asyncio
 import logging
 
@@ -27,7 +28,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_tcp_server_transport(spec):
+async def open_tcp_server_transport(spec: str) -> Transport:
     '''
     Open a TCP server transport.
     The parameter string has this syntax:
@@ -42,7 +43,7 @@ async def open_tcp_server_transport(spec):
         async def close(self):
             await super().close()
 
-    class TcpServerProtocol:
+    class TcpServerProtocol(asyncio.BaseProtocol):
         def __init__(self, packet_source, packet_sink):
             self.packet_source = packet_source
             self.packet_sink = packet_sink
diff --git a/bumble/transport/udp.py b/bumble/transport/udp.py
index e5e26fa..faa9bf0 100644
--- a/bumble/transport/udp.py
+++ b/bumble/transport/udp.py
@@ -27,7 +27,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_udp_transport(spec):
+async def open_udp_transport(spec: str) -> Transport:
     '''
     Open a UDP transport.
     The parameter string has this syntax:
diff --git a/bumble/transport/usb.py b/bumble/transport/usb.py
index 13cad60..ccc82c1 100644
--- a/bumble/transport/usb.py
+++ b/bumble/transport/usb.py
@@ -60,7 +60,7 @@ def load_libusb():
             usb1.loadLibrary(libusb_dll)
 
 
-async def open_usb_transport(spec):
+async def open_usb_transport(spec: str) -> Transport:
     '''
     Open a USB transport.
     The moniker string has this syntax:
diff --git a/bumble/transport/vhci.py b/bumble/transport/vhci.py
index ec61ab4..2b19085 100644
--- a/bumble/transport/vhci.py
+++ b/bumble/transport/vhci.py
@@ -17,6 +17,9 @@
 # -----------------------------------------------------------------------------
 import logging
 
+from typing import Optional
+
+from .common import Transport
 from .file import open_file_transport
 
 # -----------------------------------------------------------------------------
@@ -26,7 +29,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_vhci_transport(spec):
+async def open_vhci_transport(spec: Optional[str]) -> Transport:
     '''
     Open a VHCI transport (only available on some platforms).
     The parameter string is either empty (to use the default VHCI device
@@ -42,15 +45,15 @@ async def open_vhci_transport(spec):
     # Override the source's `data_received` method so that we can
     # filter out the vendor packet that is received just after the
     # initial open
-    def vhci_data_received(data):
+    def vhci_data_received(data: bytes) -> None:
         if len(data) > 0 and data[0] == HCI_VENDOR_PKT:
             if len(data) == 4:
                 hci_index = data[2] << 8 | data[3]
                 logger.info(f'HCI index {hci_index}')
         else:
-            transport.source.parser.feed_data(data)
+            transport.source.parser.feed_data(data)  # type: ignore
 
-    transport.source.data_received = vhci_data_received
+    transport.source.data_received = vhci_data_received  # type: ignore
 
     # Write the initial config
     transport.sink.on_packet(bytes([HCI_VENDOR_PKT, HCI_BREDR]))
diff --git a/bumble/transport/ws_client.py b/bumble/transport/ws_client.py
index 85f6e88..902001e 100644
--- a/bumble/transport/ws_client.py
+++ b/bumble/transport/ws_client.py
@@ -16,9 +16,9 @@
 # Imports
 # -----------------------------------------------------------------------------
 import logging
-import websockets
+import websockets.client
 
-from .common import PumpedPacketSource, PumpedPacketSink, PumpedTransport
+from .common import PumpedPacketSource, PumpedPacketSink, PumpedTransport, Transport
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -27,23 +27,25 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_ws_client_transport(spec):
+async def open_ws_client_transport(spec: str) -> Transport:
     '''
     Open a WebSocket client transport.
     The parameter string has this syntax:
-    <remote-host>:<remote-port>
+    <websocket-url>
 
-    Example: 127.0.0.1:9001
+    Example: ws://localhost:7681/v1/websocket/bt
     '''
 
-    remote_host, remote_port = spec.split(':')
-    uri = f'ws://{remote_host}:{remote_port}'
-    websocket = await websockets.connect(uri)
+    websocket = await websockets.client.connect(spec)
 
-    transport = PumpedTransport(
+    class WsTransport(PumpedTransport):
+        async def close(self):
+            await super().close()
+            await websocket.close()
+
+    transport = WsTransport(
         PumpedPacketSource(websocket.recv),
         PumpedPacketSink(websocket.send),
-        websocket.close,
     )
     transport.start()
     return transport
diff --git a/bumble/transport/ws_server.py b/bumble/transport/ws_server.py
index c7b7c6e..3c72c36 100644
--- a/bumble/transport/ws_server.py
+++ b/bumble/transport/ws_server.py
@@ -15,7 +15,6 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
-import asyncio
 import logging
 import websockets
 
@@ -28,7 +27,7 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-async def open_ws_server_transport(spec):
+async def open_ws_server_transport(spec: str) -> Transport:
     '''
     Open a WebSocket server transport.
     The parameter string has this syntax:
@@ -43,7 +42,7 @@ async def open_ws_server_transport(spec):
         def __init__(self):
             source = ParserSource()
             sink = PumpedPacketSink(self.send_packet)
-            self.connection = asyncio.get_running_loop().create_future()
+            self.connection = None
             self.server = None
 
             super().__init__(source, sink)
@@ -63,7 +62,7 @@ async def open_ws_server_transport(spec):
                 f'new connection on {connection.local_address} '
                 f'from {connection.remote_address}'
             )
-            self.connection.set_result(connection)
+            self.connection = connection
             # pylint: disable=no-member
             try:
                 async for packet in connection:
@@ -74,12 +73,14 @@ async def open_ws_server_transport(spec):
             except websockets.WebSocketException as error:
                 logger.debug(f'exception while receiving packet: {error}')
 
-            # Wait for a new connection
-            self.connection = asyncio.get_running_loop().create_future()
+            # We're now disconnected
+            self.connection = None
 
         async def send_packet(self, packet):
-            connection = await self.connection
-            return await connection.send(packet)
+            if self.connection is None:
+                logger.debug('no connection, dropping packet')
+                return
+            return await self.connection.send(packet)
 
     local_host, local_port = spec.split(':')
     transport = WsServerTransport()
diff --git a/bumble/utils.py b/bumble/utils.py
index 8a55684..dc03725 100644
--- a/bumble/utils.py
+++ b/bumble/utils.py
@@ -15,12 +15,24 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
 import asyncio
 import logging
 import traceback
 import collections
 import sys
-from typing import Awaitable, Set, TypeVar
+from typing import (
+    Awaitable,
+    Set,
+    TypeVar,
+    List,
+    Tuple,
+    Callable,
+    Any,
+    Optional,
+    Union,
+    overload,
+)
 from functools import wraps
 from pyee import EventEmitter
 
@@ -65,6 +77,102 @@ def composite_listener(cls):
 
 
 # -----------------------------------------------------------------------------
+_Handler = TypeVar('_Handler', bound=Callable)
+
+
+class EventWatcher:
+    '''A wrapper class to control the lifecycle of event handlers better.
+
+    Usage:
+    ```
+    watcher = EventWatcher()
+
+    def on_foo():
+        ...
+    watcher.on(emitter, 'foo', on_foo)
+
+    @watcher.on(emitter, 'bar')
+    def on_bar():
+        ...
+
+    # Close all event handlers watching through this watcher
+    watcher.close()
+    ```
+
+    As context:
+    ```
+    with contextlib.closing(EventWatcher()) as context:
+        @context.on(emitter, 'foo')
+        def on_foo():
+            ...
+    # on_foo() has been removed here!
+    ```
+    '''
+
+    handlers: List[Tuple[EventEmitter, str, Callable[..., Any]]]
+
+    def __init__(self) -> None:
+        self.handlers = []
+
+    @overload
+    def on(self, emitter: EventEmitter, event: str) -> Callable[[_Handler], _Handler]:
+        ...
+
+    @overload
+    def on(self, emitter: EventEmitter, event: str, handler: _Handler) -> _Handler:
+        ...
+
+    def on(
+        self, emitter: EventEmitter, event: str, handler: Optional[_Handler] = None
+    ) -> Union[_Handler, Callable[[_Handler], _Handler]]:
+        '''Watch an event until the context is closed.
+
+        Args:
+            emitter: EventEmitter to watch
+            event: Event name
+            handler: (Optional) Event handler. When nothing is passed, this method works as a decorator.
+        '''
+
+        def wrapper(f: _Handler) -> _Handler:
+            self.handlers.append((emitter, event, f))
+            emitter.on(event, f)
+            return f
+
+        return wrapper if handler is None else wrapper(handler)
+
+    @overload
+    def once(self, emitter: EventEmitter, event: str) -> Callable[[_Handler], _Handler]:
+        ...
+
+    @overload
+    def once(self, emitter: EventEmitter, event: str, handler: _Handler) -> _Handler:
+        ...
+
+    def once(
+        self, emitter: EventEmitter, event: str, handler: Optional[_Handler] = None
+    ) -> Union[_Handler, Callable[[_Handler], _Handler]]:
+        '''Watch an event for once.
+
+        Args:
+            emitter: EventEmitter to watch
+            event: Event name
+            handler: (Optional) Event handler. When nothing passed, this method works as a decorator.
+        '''
+
+        def wrapper(f: _Handler) -> _Handler:
+            self.handlers.append((emitter, event, f))
+            emitter.once(event, f)
+            return f
+
+        return wrapper if handler is None else wrapper(handler)
+
+    def close(self) -> None:
+        for emitter, event, handler in self.handlers:
+            if handler in emitter.listeners(event):
+                emitter.remove_listener(event, handler)
+
+
+# -----------------------------------------------------------------------------
 _T = TypeVar('_T')
 
 
diff --git a/bumble/vendor/__init__.py b/bumble/vendor/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/bumble/vendor/__init__.py
diff --git a/bumble/vendor/android/__init__.py b/bumble/vendor/android/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/bumble/vendor/android/__init__.py
diff --git a/bumble/vendor/android/hci.py b/bumble/vendor/android/hci.py
new file mode 100644
index 0000000..c411ecf
--- /dev/null
+++ b/bumble/vendor/android/hci.py
@@ -0,0 +1,318 @@
+# Copyright 2021-2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+import struct
+
+from bumble.hci import (
+    name_or_number,
+    hci_vendor_command_op_code,
+    Address,
+    HCI_Constant,
+    HCI_Object,
+    HCI_Command,
+    HCI_Vendor_Event,
+    STATUS_SPEC,
+)
+
+
+# -----------------------------------------------------------------------------
+# Constants
+# -----------------------------------------------------------------------------
+
+# Android Vendor Specific Commands and Events.
+# Only a subset of the commands are implemented here currently.
+#
+# pylint: disable-next=line-too-long
+# See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#chip-capabilities-and-configuration
+HCI_LE_GET_VENDOR_CAPABILITIES_COMMAND = hci_vendor_command_op_code(0x153)
+HCI_LE_APCF_COMMAND = hci_vendor_command_op_code(0x157)
+HCI_GET_CONTROLLER_ACTIVITY_ENERGY_INFO_COMMAND = hci_vendor_command_op_code(0x159)
+HCI_A2DP_HARDWARE_OFFLOAD_COMMAND = hci_vendor_command_op_code(0x15D)
+HCI_BLUETOOTH_QUALITY_REPORT_COMMAND = hci_vendor_command_op_code(0x15E)
+HCI_DYNAMIC_AUDIO_BUFFER_COMMAND = hci_vendor_command_op_code(0x15F)
+
+HCI_BLUETOOTH_QUALITY_REPORT_EVENT = 0x58
+
+HCI_Command.register_commands(globals())
+HCI_Vendor_Event.register_subevents(globals())
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        ('max_advt_instances', 1),
+        ('offloaded_resolution_of_private_address', 1),
+        ('total_scan_results_storage', 2),
+        ('max_irk_list_sz', 1),
+        ('filtering_support', 1),
+        ('max_filter', 1),
+        ('activity_energy_info_support', 1),
+        ('version_supported', 2),
+        ('total_num_of_advt_tracked', 2),
+        ('extended_scan_support', 1),
+        ('debug_logging_supported', 1),
+        ('le_address_generation_offloading_support', 1),
+        ('a2dp_source_offload_capability_mask', 4),
+        ('bluetooth_quality_report_support', 1),
+        ('dynamic_audio_buffer_support', 4),
+    ]
+)
+class HCI_LE_Get_Vendor_Capabilities_Command(HCI_Command):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#vendor-specific-capabilities
+    '''
+
+    @classmethod
+    def parse_return_parameters(cls, parameters):
+        # There are many versions of this data structure, so we need to parse until
+        # there are no more bytes to parse, and leave un-signal parameters set to
+        # None (older versions)
+        nones = {field: None for field, _ in cls.return_parameters_fields}
+        return_parameters = HCI_Object(cls.return_parameters_fields, **nones)
+
+        try:
+            offset = 0
+            for field in cls.return_parameters_fields:
+                field_name, field_type = field
+                field_value, field_size = HCI_Object.parse_field(
+                    parameters, offset, field_type
+                )
+                setattr(return_parameters, field_name, field_value)
+                offset += field_size
+        except struct.error:
+            pass
+
+        return return_parameters
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    fields=[
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_LE_APCF_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_LE_APCF_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+)
+class HCI_LE_APCF_Command(HCI_Command):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#le_apcf_command
+
+    NOTE: the subcommand-specific payloads are left as opaque byte arrays in this
+    implementation. A future enhancement may define subcommand-specific data structures.
+    '''
+
+    # APCF Subcommands
+    # TODO: use the OpenIntEnum class (when upcoming PR is merged)
+    APCF_ENABLE = 0x00
+    APCF_SET_FILTERING_PARAMETERS = 0x01
+    APCF_BROADCASTER_ADDRESS = 0x02
+    APCF_SERVICE_UUID = 0x03
+    APCF_SERVICE_SOLICITATION_UUID = 0x04
+    APCF_LOCAL_NAME = 0x05
+    APCF_MANUFACTURER_DATA = 0x06
+    APCF_SERVICE_DATA = 0x07
+    APCF_TRANSPORT_DISCOVERY_SERVICE = 0x08
+    APCF_AD_TYPE_FILTER = 0x09
+    APCF_READ_EXTENDED_FEATURES = 0xFF
+
+    OPCODE_NAMES = {
+        APCF_ENABLE: 'APCF_ENABLE',
+        APCF_SET_FILTERING_PARAMETERS: 'APCF_SET_FILTERING_PARAMETERS',
+        APCF_BROADCASTER_ADDRESS: 'APCF_BROADCASTER_ADDRESS',
+        APCF_SERVICE_UUID: 'APCF_SERVICE_UUID',
+        APCF_SERVICE_SOLICITATION_UUID: 'APCF_SERVICE_SOLICITATION_UUID',
+        APCF_LOCAL_NAME: 'APCF_LOCAL_NAME',
+        APCF_MANUFACTURER_DATA: 'APCF_MANUFACTURER_DATA',
+        APCF_SERVICE_DATA: 'APCF_SERVICE_DATA',
+        APCF_TRANSPORT_DISCOVERY_SERVICE: 'APCF_TRANSPORT_DISCOVERY_SERVICE',
+        APCF_AD_TYPE_FILTER: 'APCF_AD_TYPE_FILTER',
+        APCF_READ_EXTENDED_FEATURES: 'APCF_READ_EXTENDED_FEATURES',
+    }
+
+    @classmethod
+    def opcode_name(cls, opcode):
+        return name_or_number(cls.OPCODE_NAMES, opcode)
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        ('total_tx_time_ms', 4),
+        ('total_rx_time_ms', 4),
+        ('total_idle_time_ms', 4),
+        ('total_energy_used', 4),
+    ],
+)
+class HCI_Get_Controller_Activity_Energy_Info_Command(HCI_Command):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#le_get_controller_activity_energy_info
+    '''
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    fields=[
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_A2DP_Hardware_Offload_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_A2DP_Hardware_Offload_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+)
+class HCI_A2DP_Hardware_Offload_Command(HCI_Command):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#a2dp-hardware-offload-support
+
+    NOTE: the subcommand-specific payloads are left as opaque byte arrays in this
+    implementation. A future enhancement may define subcommand-specific data structures.
+    '''
+
+    # A2DP Hardware Offload Subcommands
+    # TODO: use the OpenIntEnum class (when upcoming PR is merged)
+    START_A2DP_OFFLOAD = 0x01
+    STOP_A2DP_OFFLOAD = 0x02
+
+    OPCODE_NAMES = {
+        START_A2DP_OFFLOAD: 'START_A2DP_OFFLOAD',
+        STOP_A2DP_OFFLOAD: 'STOP_A2DP_OFFLOAD',
+    }
+
+    @classmethod
+    def opcode_name(cls, opcode):
+        return name_or_number(cls.OPCODE_NAMES, opcode)
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    fields=[
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_Dynamic_Audio_Buffer_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        (
+            'opcode',
+            {
+                'size': 1,
+                'mapper': lambda x: HCI_Dynamic_Audio_Buffer_Command.opcode_name(x),
+            },
+        ),
+        ('payload', '*'),
+    ],
+)
+class HCI_Dynamic_Audio_Buffer_Command(HCI_Command):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#dynamic-audio-buffer-command
+
+    NOTE: the subcommand-specific payloads are left as opaque byte arrays in this
+    implementation. A future enhancement may define subcommand-specific data structures.
+    '''
+
+    # Dynamic Audio Buffer Subcommands
+    # TODO: use the OpenIntEnum class (when upcoming PR is merged)
+    GET_AUDIO_BUFFER_TIME_CAPABILITY = 0x01
+
+    OPCODE_NAMES = {
+        GET_AUDIO_BUFFER_TIME_CAPABILITY: 'GET_AUDIO_BUFFER_TIME_CAPABILITY',
+    }
+
+    @classmethod
+    def opcode_name(cls, opcode):
+        return name_or_number(cls.OPCODE_NAMES, opcode)
+
+
+# -----------------------------------------------------------------------------
+@HCI_Vendor_Event.event(
+    fields=[
+        ('quality_report_id', 1),
+        ('packet_types', 1),
+        ('connection_handle', 2),
+        ('connection_role', {'size': 1, 'mapper': HCI_Constant.role_name}),
+        ('tx_power_level', -1),
+        ('rssi', -1),
+        ('snr', 1),
+        ('unused_afh_channel_count', 1),
+        ('afh_select_unideal_channel_count', 1),
+        ('lsto', 2),
+        ('connection_piconet_clock', 4),
+        ('retransmission_count', 4),
+        ('no_rx_count', 4),
+        ('nak_count', 4),
+        ('last_tx_ack_timestamp', 4),
+        ('flow_off_count', 4),
+        ('last_flow_on_timestamp', 4),
+        ('buffer_overflow_bytes', 4),
+        ('buffer_underflow_bytes', 4),
+        ('bdaddr', Address.parse_address),
+        ('cal_failed_item_count', 1),
+        ('tx_total_packets', 4),
+        ('tx_unacked_packets', 4),
+        ('tx_flushed_packets', 4),
+        ('tx_last_subevent_packets', 4),
+        ('crc_error_packets', 4),
+        ('rx_duplicate_packets', 4),
+        ('vendor_specific_parameters', '*'),
+    ]
+)
+class HCI_Bluetooth_Quality_Report_Event(HCI_Vendor_Event):
+    # pylint: disable=line-too-long
+    '''
+    See https://source.android.com/docs/core/connect/bluetooth/hci_requirements#bluetooth-quality-report-sub-event
+    '''
diff --git a/bumble/vendor/zephyr/__init__.py b/bumble/vendor/zephyr/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/bumble/vendor/zephyr/__init__.py
diff --git a/bumble/vendor/zephyr/hci.py b/bumble/vendor/zephyr/hci.py
new file mode 100644
index 0000000..9ffb3c3
--- /dev/null
+++ b/bumble/vendor/zephyr/hci.py
@@ -0,0 +1,88 @@
+# Copyright 2021-2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+from bumble.hci import (
+    hci_vendor_command_op_code,
+    HCI_Command,
+    STATUS_SPEC,
+)
+
+
+# -----------------------------------------------------------------------------
+# Constants
+# -----------------------------------------------------------------------------
+
+# Zephyr RTOS Vendor Specific Commands and Events.
+# Only a subset of the commands are implemented here currently.
+#
+# pylint: disable-next=line-too-long
+# See https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/bluetooth/hci_vs.h
+HCI_WRITE_TX_POWER_LEVEL_COMMAND = hci_vendor_command_op_code(0x000E)
+HCI_READ_TX_POWER_LEVEL_COMMAND = hci_vendor_command_op_code(0x000F)
+
+HCI_Command.register_commands(globals())
+
+
+# -----------------------------------------------------------------------------
+class TX_Power_Level_Command:
+    '''
+    Base class for read and write TX power level HCI commands
+    '''
+
+    TX_POWER_HANDLE_TYPE_ADV = 0x00
+    TX_POWER_HANDLE_TYPE_SCAN = 0x01
+    TX_POWER_HANDLE_TYPE_CONN = 0x02
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    fields=[('handle_type', 1), ('connection_handle', 2), ('tx_power_level', -1)],
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        ('handle_type', 1),
+        ('connection_handle', 2),
+        ('selected_tx_power_level', -1),
+    ],
+)
+class HCI_Write_Tx_Power_Level_Command(HCI_Command, TX_Power_Level_Command):
+    '''
+    Write TX power level. See BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL in
+    https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/bluetooth/hci_vs.h
+
+    Power level is in dB. Connection handle for TX_POWER_HANDLE_TYPE_ADV and
+    TX_POWER_HANDLE_TYPE_SCAN should be zero.
+    '''
+
+
+# -----------------------------------------------------------------------------
+@HCI_Command.command(
+    fields=[('handle_type', 1), ('connection_handle', 2)],
+    return_parameters_fields=[
+        ('status', STATUS_SPEC),
+        ('handle_type', 1),
+        ('connection_handle', 2),
+        ('tx_power_level', -1),
+    ],
+)
+class HCI_Read_Tx_Power_Level_Command(HCI_Command, TX_Power_Level_Command):
+    '''
+    Read TX power level. See BT_HCI_OP_VS_READ_TX_POWER_LEVEL in
+    https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/bluetooth/hci_vs.h
+
+    Power level is in dB. Connection handle for TX_POWER_HANDLE_TYPE_ADV and
+    TX_POWER_HANDLE_TYPE_SCAN should be zero.
+    '''
diff --git a/docs/mkdocs/mkdocs.yml b/docs/mkdocs/mkdocs.yml
index 0cf65f1..82a6f41 100644
--- a/docs/mkdocs/mkdocs.yml
+++ b/docs/mkdocs/mkdocs.yml
@@ -64,6 +64,7 @@ nav:
     - Linux: platforms/linux.md
     - Windows: platforms/windows.md
     - Android: platforms/android.md
+    - Zephyr: platforms/zephyr.md
   - Examples:
     - Overview: examples/index.md
 
diff --git a/docs/mkdocs/src/downloads/zephyr/hci_usb.zip b/docs/mkdocs/src/downloads/zephyr/hci_usb.zip
new file mode 100644
index 0000000..5e1dfc9
--- /dev/null
+++ b/docs/mkdocs/src/downloads/zephyr/hci_usb.zip
diff --git a/docs/mkdocs/src/platforms/index.md b/docs/mkdocs/src/platforms/index.md
index a93e947..858785f 100644
--- a/docs/mkdocs/src/platforms/index.md
+++ b/docs/mkdocs/src/platforms/index.md
@@ -9,3 +9,4 @@ For platform-specific information, see the following pages:
   * :material-linux: Linux - see the [Linux platform page](linux.md)
   * :material-microsoft-windows: Windows - see the [Windows platform page](windows.md)
   * :material-android: Android - see the [Android platform page](android.md)
+  * :material-memory: Zephyr - see the [Zephyr platform page](zephyr.md)
diff --git a/docs/mkdocs/src/platforms/zephyr.md b/docs/mkdocs/src/platforms/zephyr.md
new file mode 100644
index 0000000..0e68247
--- /dev/null
+++ b/docs/mkdocs/src/platforms/zephyr.md
@@ -0,0 +1,51 @@
+:material-memory: ZEPHYR PLATFORM
+=================================
+
+Set TX Power on nRF52840
+------------------------
+
+The Nordic nRF52840 supports Zephyr's vendor specific HCI command for setting TX
+power during advertising, connection, or scanning. With the example [HCI
+USB](https://docs.zephyrproject.org/latest/samples/bluetooth/hci_usb/README.html)
+application, an [nRF52840
+dongle](https://www.nordicsemi.com/Products/Development-
+hardware/nRF52840-Dongle) can be used as a Bumble controller.
+
+To add dynamic TX power support to the HCI USB application, add the following to
+`zephyr/samples/bluetooth/hci_usb/prj.conf` and build.
+
+```
+CONFIG_BT_CTLR_ADVANCED_FEATURES=y
+CONFIG_BT_CTLR_CONN_RSSI=y
+CONFIG_BT_CTLR_TX_PWR_DYNAMIC_CONTROL=y
+```
+
+Alternatively, a prebuilt firmware application can be downloaded here:
+[hci_usb.zip](../downloads/zephyr/hci_usb.zip).
+
+Put the nRF52840 dongle into bootloader mode by pressing the RESET button. The
+LED should pulse red. Load the firmware application with the `nrfutil` tool:
+
+```
+nrfutil dfu usb-serial -pkg hci_usb.zip -p /dev/ttyACM0
+```
+
+The vendor specific HCI commands to read and write TX power are defined in
+`bumble/vendor/zephyr/hci.py` and may be used as such:
+
+```python
+from bumble.vendor.zephyr.hci import HCI_Write_Tx_Power_Level_Command
+
+# set advertising power to -4 dB
+response = await host.send_command(
+    HCI_Write_Tx_Power_Level_Command(
+        handle_type=HCI_Write_Tx_Power_Level_Command.TX_POWER_HANDLE_TYPE_ADV,
+        connection_handle=0,
+        tx_power_level=-4,
+    )
+)
+
+if response.return_parameters.status == HCI_SUCCESS:
+    print(f"TX power set to {response.return_parameters.selected_tx_power_level}")
+
+```
diff --git a/environment.yml b/environment.yml
index 17b040c..2e927cb 100644
--- a/environment.yml
+++ b/environment.yml
@@ -3,7 +3,7 @@ channels:
   - defaults
   - conda-forge
 dependencies:
-  - pip=20
+  - pip=23
   - python=3.8
   - pip:
     - --editable .[development,documentation,test]
diff --git a/examples/run_hfp_gateway.py b/examples/run_hfp_gateway.py
index eac5473..13a2ed9 100644
--- a/examples/run_hfp_gateway.py
+++ b/examples/run_hfp_gateway.py
@@ -16,11 +16,9 @@
 # Imports
 # -----------------------------------------------------------------------------
 import asyncio
-import collections
 import sys
 import os
 import logging
-from typing import Union
 
 from bumble.colors import color
 
@@ -32,8 +30,7 @@ from bumble.core import (
     BT_RFCOMM_PROTOCOL_ID,
     BT_BR_EDR_TRANSPORT,
 )
-from bumble import rfcomm
-from bumble.rfcomm import Client
+from bumble import rfcomm, hfp
 from bumble.sdp import (
     Client as SDP_Client,
     DataElement,
@@ -48,61 +45,6 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-# Protocol Support
-# -----------------------------------------------------------------------------
-
-# -----------------------------------------------------------------------------
-class HfpProtocol:
-    dlc: rfcomm.DLC
-    buffer: str
-    lines: collections.deque
-    lines_available: asyncio.Event
-
-    def __init__(self, dlc: rfcomm.DLC) -> None:
-        self.dlc = dlc
-        self.buffer = ''
-        self.lines = collections.deque()
-        self.lines_available = asyncio.Event()
-
-        dlc.sink = self.feed
-
-    def feed(self, data: Union[bytes, str]) -> None:
-        # Convert the data to a string if needed
-        if isinstance(data, bytes):
-            data = data.decode('utf-8')
-
-        logger.debug(f'<<< Data received: {data}')
-
-        # Add to the buffer and look for lines
-        self.buffer += data
-        while (separator := self.buffer.find('\r')) >= 0:
-            line = self.buffer[:separator].strip()
-            self.buffer = self.buffer[separator + 1 :]
-            if len(line) > 0:
-                self.on_line(line)
-
-    def on_line(self, line: str) -> None:
-        self.lines.append(line)
-        self.lines_available.set()
-
-    def send_command_line(self, line: str) -> None:
-        logger.debug(color(f'>>> {line}', 'yellow'))
-        self.dlc.write(line + '\r')
-
-    def send_response_line(self, line: str) -> None:
-        logger.debug(color(f'>>> {line}', 'yellow'))
-        self.dlc.write('\r\n' + line + '\r\n')
-
-    async def next_line(self) -> str:
-        await self.lines_available.wait()
-        line = self.lines.popleft()
-        if not self.lines:
-            self.lines_available.clear()
-        logger.debug(color(f'<<< {line}', 'green'))
-        return line
-
-
-# -----------------------------------------------------------------------------
 # pylint: disable-next=too-many-nested-blocks
 async def list_rfcomm_channels(device, connection):
     # Connect to the SDP Server
@@ -241,7 +183,7 @@ async def main():
 
         # Create a client and start it
         print('@@@ Starting to RFCOMM client...')
-        rfcomm_client = Client(device, connection)
+        rfcomm_client = rfcomm.Client(device, connection)
         rfcomm_mux = await rfcomm_client.start()
         print('@@@ Started')
 
@@ -256,7 +198,7 @@ async def main():
             return
 
         # Protocol loop (just for testing at this point)
-        protocol = HfpProtocol(session)
+        protocol = hfp.HfpProtocol(session)
         while True:
             line = await protocol.next_line()
 
diff --git a/examples/run_rfcomm_server.py b/examples/run_rfcomm_server.py
index 71feca9..41915a4 100644
--- a/examples/run_rfcomm_server.py
+++ b/examples/run_rfcomm_server.py
@@ -20,83 +20,109 @@ import sys
 import os
 import logging
 
+from bumble.core import UUID
 from bumble.device import Device
 from bumble.transport import open_transport_or_link
-from bumble.core import BT_L2CAP_PROTOCOL_ID, BT_RFCOMM_PROTOCOL_ID, UUID
 from bumble.rfcomm import Server
-from bumble.sdp import (
-    DataElement,
-    ServiceAttribute,
-    SDP_PUBLIC_BROWSE_ROOT,
-    SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
-    SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
-    SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
-    SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
-)
+from bumble.utils import AsyncRunner
+from bumble.rfcomm import make_service_sdp_records
 
 
 # -----------------------------------------------------------------------------
-def sdp_records(channel):
+def sdp_records(channel, uuid):
+    service_record_handle = 0x00010001
     return {
-        0x00010001: [
-            ServiceAttribute(
-                SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
-                DataElement.unsigned_integer_32(0x00010001),
-            ),
-            ServiceAttribute(
-                SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
-                DataElement.sequence([DataElement.uuid(SDP_PUBLIC_BROWSE_ROOT)]),
-            ),
-            ServiceAttribute(
-                SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
-                DataElement.sequence(
-                    [DataElement.uuid(UUID('E6D55659-C8B4-4B85-96BB-B1143AF6D3AE'))]
-                ),
-            ),
-            ServiceAttribute(
-                SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
-                DataElement.sequence(
-                    [
-                        DataElement.sequence([DataElement.uuid(BT_L2CAP_PROTOCOL_ID)]),
-                        DataElement.sequence(
-                            [
-                                DataElement.uuid(BT_RFCOMM_PROTOCOL_ID),
-                                DataElement.unsigned_integer_8(channel),
-                            ]
-                        ),
-                    ]
-                ),
-            ),
-        ]
+        service_record_handle: make_service_sdp_records(
+            service_record_handle, channel, UUID(uuid)
+        )
     }
 
 
 # -----------------------------------------------------------------------------
-def on_dlc(dlc):
-    print('*** DLC connected', dlc)
-    dlc.sink = lambda data: on_rfcomm_data_received(dlc, data)
+def on_rfcomm_session(rfcomm_session, tcp_server):
+    print('*** RFComm session connected', rfcomm_session)
+    tcp_server.attach_session(rfcomm_session)
 
 
 # -----------------------------------------------------------------------------
-def on_rfcomm_data_received(dlc, data):
-    print(f'<<< Data received: {data.hex()}')
-    try:
-        message = data.decode('utf-8')
-        print(f'<<< Message = {message}')
-    except Exception:
-        pass
+class TcpServerProtocol(asyncio.Protocol):
+    def __init__(self, server):
+        self.server = server
 
-    # Echo everything back
-    dlc.write(data)
+    def connection_made(self, transport):
+        peer_name = transport.get_extra_info('peer_name')
+        print(f'<<< TCP Server: connection from {peer_name}')
+        if self.server:
+            self.server.tcp_transport = transport
+        else:
+            transport.close()
+
+    def connection_lost(self, exc):
+        print('<<< TCP Server: connection lost')
+        if self.server:
+            self.server.tcp_transport = None
+
+    def data_received(self, data):
+        print(f'<<< TCP Server: data received: {len(data)} bytes - {data.hex()}')
+        if self.server:
+            self.server.tcp_data_received(data)
+
+
+# -----------------------------------------------------------------------------
+class TcpServer:
+    def __init__(self, port):
+        self.rfcomm_session = None
+        self.tcp_transport = None
+        AsyncRunner.spawn(self.run(port))
+
+    def attach_session(self, rfcomm_session):
+        if self.rfcomm_session:
+            self.rfcomm_session.sink = None
+
+        self.rfcomm_session = rfcomm_session
+        rfcomm_session.sink = self.rfcomm_data_received
+
+    def rfcomm_data_received(self, data):
+        print(f'<<< RFCOMM Data: {data.hex()}')
+        if self.tcp_transport:
+            self.tcp_transport.write(data)
+        else:
+            print('!!! no TCP connection, dropping data')
+
+    def tcp_data_received(self, data):
+        if self.rfcomm_session:
+            self.rfcomm_session.write(data)
+        else:
+            print('!!! no RFComm session, dropping data')
+
+    async def run(self, port):
+        print(f'$$$ Starting TCP server on port {port}')
+
+        server = await asyncio.get_running_loop().create_server(
+            lambda: TcpServerProtocol(self), '127.0.0.1', port
+        )
+
+        async with server:
+            await server.serve_forever()
 
 
 # -----------------------------------------------------------------------------
 async def main():
-    if len(sys.argv) < 3:
-        print('Usage: run_rfcomm_server.py <device-config> <transport-spec>')
-        print('example: run_rfcomm_server.py classic2.json usb:04b4:f901')
+    if len(sys.argv) < 4:
+        print(
+            'Usage: run_rfcomm_server.py <device-config> <transport-spec> '
+            '<tcp-port> [<uuid>]'
+        )
+        print('example: run_rfcomm_server.py classic2.json usb:0 8888')
         return
 
+    tcp_port = int(sys.argv[3])
+
+    if len(sys.argv) >= 5:
+        uuid = sys.argv[4]
+    else:
+        uuid = 'E6D55659-C8B4-4B85-96BB-B1143AF6D3AE'
+
     print('<<< connecting to HCI...')
     async with await open_transport_or_link(sys.argv[2]) as (hci_source, hci_sink):
         print('<<< connected')
@@ -105,15 +131,20 @@ async def main():
         device = Device.from_config_file_with_hci(sys.argv[1], hci_source, hci_sink)
         device.classic_enabled = True
 
-        # Create and register a server
+        # Create a TCP server
+        tcp_server = TcpServer(tcp_port)
+
+        # Create and register an RFComm server
         rfcomm_server = Server(device)
 
         # Listen for incoming DLC connections
-        channel_number = rfcomm_server.listen(on_dlc)
-        print(f'### Listening for connection on channel {channel_number}')
+        channel_number = rfcomm_server.listen(
+            lambda session: on_rfcomm_session(session, tcp_server)
+        )
+        print(f'### Listening for RFComm connections on channel {channel_number}')
 
         # Setup the SDP to advertise this channel
-        device.sdp_service_records = sdp_records(channel_number)
+        device.sdp_service_records = sdp_records(channel_number, uuid)
 
         # Start the controller
         await device.power_on()
diff --git a/rust/Cargo.lock b/rust/Cargo.lock
index 399f916..c2d0cd3 100644
--- a/rust/Cargo.lock
+++ b/rust/Cargo.lock
@@ -4,9 +4,9 @@ version = 3
 
 [[package]]
 name = "addr2line"
-version = "0.20.0"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f4fa78e18c64fce05e902adecd7a5eed15a5e0a3439f7b0e169f0252214865e3"
+checksum = "8a30b2e23b9e17a9f90641c7ab1549cd9b44f296d3ccbf309d2863cfe398a0cb"
 dependencies = [
  "gimli",
 ]
@@ -19,33 +19,32 @@ checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
 [[package]]
 name = "aho-corasick"
-version = "1.0.2"
+version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "43f6cb1bf222025340178f382c426f13757b2960e89779dfcb319c32542a5a41"
+checksum = "0c378d78423fdad8089616f827526ee33c19f2fddbd5de1629152c9593ba4783"
 dependencies = [
  "memchr",
 ]
 
 [[package]]
 name = "anstream"
-version = "0.3.2"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ca84f3628370c59db74ee214b3263d58f9aadd9b4fe7e711fd87dc452b7f163"
+checksum = "b1f58811cfac344940f1a400b6e6231ce35171f614f26439e80f8c1465c5cc0c"
 dependencies = [
  "anstyle",
  "anstyle-parse",
  "anstyle-query",
  "anstyle-wincon",
  "colorchoice",
- "is-terminal",
  "utf8parse",
 ]
 
 [[package]]
 name = "anstyle"
-version = "1.0.1"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3a30da5c5f2d5e72842e00bcb57657162cdabef0931f40e2deb9b4140440cecd"
+checksum = "15c4c2c83f81532e5845a733998b6971faca23490340a418e9b72a3ec9de12ea"
 
 [[package]]
 name = "anstyle-parse"
@@ -67,9 +66,9 @@ dependencies = [
 
 [[package]]
 name = "anstyle-wincon"
-version = "1.0.1"
+version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "180abfa45703aebe0093f79badacc01b8fd4ea2e35118747e5811127f926e188"
+checksum = "58f54d10c6dfa51283a066ceab3ec1ab78d13fae00aa49243a45e4571fb79dfd"
 dependencies = [
  "anstyle",
  "windows-sys",
@@ -77,9 +76,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.72"
+version = "1.0.75"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b13c32d80ecc7ab747b80c3784bce54ee8a7a0cc4fbda9bf4cda2cf6fe90854"
+checksum = "a4668cab20f66d8d020e1fbc0ebe47217433c1b6c8f2040faf858554e394ace6"
 
 [[package]]
 name = "atty"
@@ -100,9 +99,9 @@ checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
 [[package]]
 name = "backtrace"
-version = "0.3.68"
+version = "0.3.69"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4319208da049c43661739c5fade2ba182f09d1dc2299b32298d3a31692b17e12"
+checksum = "2089b7e3f35b9dd2d0ed921ead4f6d318c27680d4a5bd167b3ee120edb105837"
 dependencies = [
  "addr2line",
  "cc",
@@ -114,6 +113,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "base64"
+version = "0.21.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "414dcefbc63d77c526a76b3afcf6fbb9b5e2791c19c3aa2297733208750c6e53"
+
+[[package]]
 name = "bitflags"
 version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -121,17 +126,31 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitflags"
-version = "2.3.3"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
+
+[[package]]
+name = "bstr"
+version = "1.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "630be753d4e58660abd17930c71b647fe46c27ea6b63cc59e1e3851406972e42"
+checksum = "4c2f7349907b712260e64b0afe2f84692af14a454be26187d9df565c7f69266a"
+dependencies = [
+ "memchr",
+ "serde",
+]
 
 [[package]]
 name = "bumble"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "clap 4.3.19",
+ "clap 4.4.1",
+ "directories",
  "env_logger",
+ "file-header",
+ "futures",
+ "globset",
  "hex",
  "itertools",
  "lazy_static",
@@ -142,6 +161,7 @@ dependencies = [
  "pyo3",
  "pyo3-asyncio",
  "rand",
+ "reqwest",
  "rusb",
  "strum",
  "strum_macros",
@@ -151,6 +171,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "bumpalo"
+version = "3.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3e2c3daef883ecc1b5d58c15adae93470a91d425f3532ba1695849656af3fc1"
+
+[[package]]
 name = "bytes"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -158,9 +184,9 @@ checksum = "89b2fd2a0dcf38d7971e2194b6b6eebab45ae01067456a7fd93d5547a61b70be"
 
 [[package]]
 name = "cc"
-version = "1.0.81"
+version = "1.0.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c6b2562119bf28c3439f7f02db99faf0aa1a8cdfe5772a2ee155d32227239f0"
+checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
 dependencies = [
  "libc",
 ]
@@ -188,9 +214,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.3.19"
+version = "4.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5fd304a20bff958a57f04c4e96a2e7594cc4490a0e809cbd48bb6437edaa452d"
+checksum = "7c8d502cbaec4595d2e7d5f61e318f05417bd2b66fdc3809498f0d3fdf0bea27"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -199,26 +225,26 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.3.19"
+version = "4.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01c6a3f08f1fe5662a35cfe393aec09c4df95f60ee93b7556505260f75eee9e1"
+checksum = "5891c7bc0edb3e1c2204fc5e94009affabeb1821c9e5fdc3959536c5c0bb984d"
 dependencies = [
  "anstream",
  "anstyle",
- "clap_lex 0.5.0",
+ "clap_lex 0.5.1",
  "strsim",
 ]
 
 [[package]]
 name = "clap_derive"
-version = "4.3.12"
+version = "4.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "54a9bb5758fc5dfe728d1019941681eccaf0cf8a4189b692a0ee2f2ecf90a050"
+checksum = "c9fd1a5729c4548118d7d70ff234a44868d00489a4b6597b0b020918a0e91a1a"
 dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn 2.0.28",
+ "syn 2.0.29",
 ]
 
 [[package]]
@@ -232,9 +258,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.5.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2da6da31387c7e4ef160ffab6d5e7f00c42626fe39aea70a7b0f1773f7dd6c1b"
+checksum = "cd7cc57abe963c6d3b9d8be5b06ba7c8957a930305ca90304f24ef040aa6f961"
 
 [[package]]
 name = "colorchoice"
@@ -243,12 +269,125 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "acbf1af155f9b9ef647e42cdc158db4b64a1b61f743629225fde6f3e0be2a7c7"
 
 [[package]]
+name = "core-foundation"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "194a7a9e6de53fa55116934067c844d9d749312f75c6f6d0980e8c252f8c2146"
+dependencies = [
+ "core-foundation-sys",
+ "libc",
+]
+
+[[package]]
+name = "core-foundation-sys"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e496a50fda8aacccc86d7529e2c1e0892dbd0f898a6b5645b5561b89c3210efa"
+
+[[package]]
+name = "crossbeam"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2801af0d36612ae591caa9568261fddce32ce6e08a7275ea334a06a4ad021a2c"
+dependencies = [
+ "cfg-if",
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-epoch",
+ "crossbeam-queue",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a33c2bf77f2df06183c3aa30d1e96c0695a313d4f9c453cc3762a6db39f99200"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce6fd6f855243022dcecf8702fef0c297d4338e226845fe067f6341ad9fa0cef"
+dependencies = [
+ "cfg-if",
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae211234986c545741a7dc064309f67ee1e5ad243d0e48335adc0484d960bcc7"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+ "crossbeam-utils",
+ "memoffset 0.9.0",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-queue"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d1cfb3ea8a53f37c40dea2c7bedcbd88bdfae54f5e2175d6ecaff1c988353add"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a22b2d63d4d1dc0b7f1b6b2747dd0088008a9be28b6ddf0b1e7d335e3037294"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "directories"
+version = "5.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a49173b84e034382284f27f1af4dcbbd231ffa358c0fe316541a7337f376a35"
+dependencies = [
+ "dirs-sys",
+]
+
+[[package]]
+name = "dirs-sys"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "520f05a5cbd335fae5a99ff7a6ab8627577660ee5cfd6a94a6a929b52ff0321c"
+dependencies = [
+ "libc",
+ "option-ext",
+ "redox_users",
+ "windows-sys",
+]
+
+[[package]]
 name = "either"
 version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a26ae43d7bcc3b814de94796a5e736d4029efb0ee900c12e2d54c993ad1a1e07"
 
 [[package]]
+name = "encoding_rs"
+version = "0.8.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7268b386296a025e474d5140678f75d6de9493ae55a5d709eeb9dd08149945e1"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
 name = "env_logger"
 version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -263,9 +402,9 @@ dependencies = [
 
 [[package]]
 name = "errno"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6b30f669a7961ef1631673d2766cc92f52d64f7ef354d4fe0ddfd30ed52f0f4f"
+checksum = "136526188508e25c6fef639d7927dfb3e0e3084488bf202267829cf7fc23dbdd"
 dependencies = [
  "errno-dragonfly",
  "libc",
@@ -289,6 +428,49 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6999dc1837253364c2ebb0704ba97994bd874e8f195d665c50b7548f6ea92764"
 
 [[package]]
+name = "file-header"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5568149106e77ae33bc3a2c3ef3839cbe63ffa4a8dd4a81612a6f9dfdbc2e9f"
+dependencies = [
+ "crossbeam",
+ "lazy_static",
+ "license",
+ "thiserror",
+ "walkdir",
+]
+
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
+[[package]]
+name = "foreign-types"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6f339eb8adc052cd2ca78910fda869aefa38d22d5cb648e6485e4d3fc06f3b1"
+dependencies = [
+ "foreign-types-shared",
+]
+
+[[package]]
+name = "foreign-types-shared"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "00b0228411908ca8685dba7fc2cdd70ec9990a6e753e89b6ac91a84c40fbaf4b"
+
+[[package]]
+name = "form_urlencoded"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a62bc1cf6f830c2ec14a513a9fb124d0a213a629668a4186f329db21fe045652"
+dependencies = [
+ "percent-encoding",
+]
+
+[[package]]
 name = "futures"
 version = "0.3.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -344,7 +526,7 @@ checksum = "89ca545a94061b6365f2c7355b4b32bd20df3ff95f02da9329b34ccc3bd6ee72"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.28",
+ "syn 2.0.29",
 ]
 
 [[package]]
@@ -390,9 +572,41 @@ dependencies = [
 
 [[package]]
 name = "gimli"
-version = "0.27.3"
+version = "0.28.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6c80984affa11d98d1b88b66ac8853f143217b399d3c74116778ff8fdb4ed2e"
+checksum = "6fb8d784f27acf97159b40fc4db5ecd8aa23b9ad5ef69cdd136d3bc80665f0c0"
+
+[[package]]
+name = "globset"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "759c97c1e17c55525b57192c06a267cda0ac5210b222d6b82189a2338fa1c13d"
+dependencies = [
+ "aho-corasick",
+ "bstr",
+ "fnv",
+ "log",
+ "regex",
+]
+
+[[package]]
+name = "h2"
+version = "0.3.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91fc23aa11be92976ef4729127f1a74adf36d8436f7816b185d18df956790833"
+dependencies = [
+ "bytes",
+ "fnv",
+ "futures-core",
+ "futures-sink",
+ "futures-util",
+ "http",
+ "indexmap",
+ "slab",
+ "tokio",
+ "tokio-util",
+ "tracing",
+]
 
 [[package]]
 name = "hashbrown"
@@ -428,12 +642,93 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
+name = "http"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd6effc99afb63425aff9b05836f029929e345a6148a14b7ecd5ab67af944482"
+dependencies = [
+ "bytes",
+ "fnv",
+ "itoa",
+]
+
+[[package]]
+name = "http-body"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d5f38f16d184e36f2408a55281cd658ecbd3ca05cce6d6510a176eca393e26d1"
+dependencies = [
+ "bytes",
+ "http",
+ "pin-project-lite",
+]
+
+[[package]]
+name = "httparse"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d897f394bad6a705d5f4104762e116a75639e470d80901eed05a860a95cb1904"
+
+[[package]]
+name = "httpdate"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
+
+[[package]]
 name = "humantime"
 version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
 
 [[package]]
+name = "hyper"
+version = "0.14.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffb1cfd654a8219eaef89881fdb3bb3b1cdc5fa75ded05d6933b2b382e395468"
+dependencies = [
+ "bytes",
+ "futures-channel",
+ "futures-core",
+ "futures-util",
+ "h2",
+ "http",
+ "http-body",
+ "httparse",
+ "httpdate",
+ "itoa",
+ "pin-project-lite",
+ "socket2 0.4.9",
+ "tokio",
+ "tower-service",
+ "tracing",
+ "want",
+]
+
+[[package]]
+name = "hyper-tls"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6183ddfa99b85da61a140bea0efc93fdf56ceaa041b37d553518030827f9905"
+dependencies = [
+ "bytes",
+ "hyper",
+ "native-tls",
+ "tokio",
+ "tokio-native-tls",
+]
+
+[[package]]
+name = "idna"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d20d6b07bfbc108882d88ed8e37d39636dcc260e15e30c45e6ba089610b917c"
+dependencies = [
+ "unicode-bidi",
+ "unicode-normalization",
+]
+
+[[package]]
 name = "indexmap"
 version = "1.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -451,9 +746,15 @@ checksum = "bfa799dd5ed20a7e349f3b4639aa80d74549c81716d9ec4f994c9b5815598306"
 
 [[package]]
 name = "inventory"
-version = "0.3.11"
+version = "0.3.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1be380c410bf0595e94992a648ea89db4dd3f3354ba54af206fd2a68cf5ac8e"
+
+[[package]]
+name = "ipnet"
+version = "2.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a53088c87cf71c9d4f3372a2cb9eea1e7b8a0b1bf8b7f7d23fe5b76dbb07e63b"
+checksum = "28b29a3cd74f0f4598934efe3aeba42bae0eb4680554128851ebbecb02af14e6"
 
 [[package]]
 name = "is-terminal"
@@ -476,6 +777,21 @@ dependencies = [
 ]
 
 [[package]]
+name = "itoa"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
+
+[[package]]
+name = "js-sys"
+version = "0.3.64"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5f195fe497f702db0f318b07fdd68edb16955aed830df8363d837542f8f935a"
+dependencies = [
+ "wasm-bindgen",
+]
+
+[[package]]
 name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -500,6 +816,17 @@ dependencies = [
 ]
 
 [[package]]
+name = "license"
+version = "3.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b66615d42e949152327c402e03cd29dab8bff91ce470381ac2ca6d380d8d9946"
+dependencies = [
+ "reword",
+ "serde",
+ "serde_json",
+]
+
+[[package]]
 name = "linux-raw-sys"
 version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -517,15 +844,15 @@ dependencies = [
 
 [[package]]
 name = "log"
-version = "0.4.19"
+version = "0.4.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
+checksum = "b5e6163cb8c49088c2c36f57875e58ccd8c87c7427f7fbd50ea6710b2f3f2e8f"
 
 [[package]]
 name = "memchr"
-version = "2.5.0"
+version = "2.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+checksum = "5486aed0026218e61b8a01d5fbd5a0a134649abb71a0e53b7bc088529dced86e"
 
 [[package]]
 name = "memoffset"
@@ -546,6 +873,21 @@ dependencies = [
 ]
 
 [[package]]
+name = "memoffset"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a634b1c61a95585bd15607c6ab0c4e5b226e695ff2800ba0cdccddf208c406c"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "mime"
+version = "0.3.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
+
+[[package]]
 name = "minimal-lexical"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -572,17 +914,34 @@ dependencies = [
 ]
 
 [[package]]
+name = "native-tls"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "07226173c32f2926027b63cce4bcd8076c3552846cbe7925f3aaffeac0a3b92e"
+dependencies = [
+ "lazy_static",
+ "libc",
+ "log",
+ "openssl",
+ "openssl-probe",
+ "openssl-sys",
+ "schannel",
+ "security-framework",
+ "security-framework-sys",
+ "tempfile",
+]
+
+[[package]]
 name = "nix"
-version = "0.26.2"
+version = "0.26.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bfdda3d196821d6af13126e40375cdf7da646a96114af134d5f417a9a1dc8e1a"
+checksum = "598beaf3cc6fdd9a5dfb1630c2800c7acd31df7aaf0f565796fba2b53ca1af1b"
 dependencies = [
  "bitflags 1.3.2",
  "cfg-if",
  "libc",
  "memoffset 0.7.1",
  "pin-utils",
- "static_assertions",
 ]
 
 [[package]]
@@ -607,9 +966,9 @@ dependencies = [
 
 [[package]]
 name = "object"
-version = "0.31.1"
+version = "0.32.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8bda667d9f2b5051b8833f59f3bf748b28ef54f850f4fcb389a252aa383866d1"
+checksum = "77ac5bbd07aea88c60a577a1ce218075ffd59208b2d7ca97adf9bfc5aeb21ebe"
 dependencies = [
  "memchr",
 ]
@@ -621,6 +980,56 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
 
 [[package]]
+name = "openssl"
+version = "0.10.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bac25ee399abb46215765b1cb35bc0212377e58a061560d8b29b024fd0430e7c"
+dependencies = [
+ "bitflags 2.4.0",
+ "cfg-if",
+ "foreign-types",
+ "libc",
+ "once_cell",
+ "openssl-macros",
+ "openssl-sys",
+]
+
+[[package]]
+name = "openssl-macros"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a948666b637a0f465e8564c73e89d4dde00d72d4d473cc972f390fc3dcee7d9c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.29",
+]
+
+[[package]]
+name = "openssl-probe"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
+
+[[package]]
+name = "openssl-sys"
+version = "0.9.92"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db7e971c2c2bba161b2d2fdf37080177eff520b3bc044787c7f1f5f9e78d869b"
+dependencies = [
+ "cc",
+ "libc",
+ "pkg-config",
+ "vcpkg",
+]
+
+[[package]]
+name = "option-ext"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
+
+[[package]]
 name = "os_str_bytes"
 version = "6.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -650,16 +1059,22 @@ checksum = "93f00c865fe7cabf650081affecd3871070f26767e7b2070a3ffae14c654b447"
 dependencies = [
  "cfg-if",
  "libc",
- "redox_syscall",
+ "redox_syscall 0.3.5",
  "smallvec",
  "windows-targets",
 ]
 
 [[package]]
+name = "percent-encoding"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b2a4787296e9989611394c33f193f676704af1686e70b8f8033ab5ba9a35a94"
+
+[[package]]
 name = "pin-project-lite"
-version = "0.2.10"
+version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c40d25201921e5ff0c862a505c6557ea88568a4e3ace775ab55e93f2f4f9d57"
+checksum = "8afb450f006bf6385ca15ef45d71d2288452bc3683ce2e2cacc0d18e4be60b58"
 
 [[package]]
 name = "pin-utils"
@@ -778,9 +1193,9 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.32"
+version = "1.0.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "50f3b39ccfb720540debaa0164757101c08ecb8d326b15358ce76a62c7e85965"
+checksum = "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
 dependencies = [
  "proc-macro2",
 ]
@@ -817,6 +1232,15 @@ dependencies = [
 
 [[package]]
 name = "redox_syscall"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb5a58c1855b4b6819d59012155603f0b22ad30cad752600aadfcb695265519a"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
+[[package]]
+name = "redox_syscall"
 version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "567664f262709473930a4bf9e51bf2ebf3348f2e748ccc50dea20646858f8f29"
@@ -825,10 +1249,21 @@ dependencies = [
 ]
 
 [[package]]
+name = "redox_users"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b033d837a7cf162d7993aded9304e30a83213c648b6e389db233191f891e5c2b"
+dependencies = [
+ "getrandom",
+ "redox_syscall 0.2.16",
+ "thiserror",
+]
+
+[[package]]
 name = "regex"
-version = "1.9.1"
+version = "1.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2eae68fc220f7cf2532e4494aded17545fce192d59cd996e0fe7887f4ceb575"
+checksum = "12de2eff854e5fa4b1295edd650e227e9d8fb0c9e90b12e7f36d6a6811791a29"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -838,9 +1273,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.3.4"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b7b6d6190b7594385f61bd3911cd1be99dfddcfc365a4160cc2ab5bff4aed294"
+checksum = "49530408a136e16e5b486e883fbb6ba058e8e4e8ae6621a77b048b314336e629"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -849,15 +1284,61 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.7.4"
+version = "0.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e5ea92a5b6195c6ef2a0295ea818b312502c6fc94dde986c5553242e18fd4ce2"
+checksum = "dbb5fb1acd8a1a18b3dd5be62d25485eb770e05afb408a9627d14d451bae12da"
+
+[[package]]
+name = "reqwest"
+version = "0.11.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e9ad3fe7488d7e34558a2033d45a0c90b72d97b4f80705666fea71472e2e6a1"
+dependencies = [
+ "base64",
+ "bytes",
+ "encoding_rs",
+ "futures-core",
+ "futures-util",
+ "h2",
+ "http",
+ "http-body",
+ "hyper",
+ "hyper-tls",
+ "ipnet",
+ "js-sys",
+ "log",
+ "mime",
+ "native-tls",
+ "once_cell",
+ "percent-encoding",
+ "pin-project-lite",
+ "serde",
+ "serde_json",
+ "serde_urlencoded",
+ "tokio",
+ "tokio-native-tls",
+ "tower-service",
+ "url",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+ "winreg",
+]
+
+[[package]]
+name = "reword"
+version = "7.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe272098dce9ed76b479995953f748d1851261390b08f8a0ff619c885a1f0765"
+dependencies = [
+ "unicode-segmentation",
+]
 
 [[package]]
 name = "rusb"
-version = "0.9.2"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "44a8c36914f9b1a3be712c1dfa48c9b397131f9a75707e570a391735f785c5d1"
+checksum = "45fff149b6033f25e825cbb7b2c625a11ee8e6dac09264d49beb125e39aa97bf"
 dependencies = [
  "libc",
  "libusb1-sys",
@@ -871,11 +1352,11 @@ checksum = "d626bb9dae77e28219937af045c257c28bfd3f69333c512553507f5f9798cb76"
 
 [[package]]
 name = "rustix"
-version = "0.38.6"
+version = "0.38.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ee020b1716f0a80e2ace9b03441a749e402e86712f15f16fe8a8f75afac732f"
+checksum = "ed6248e1caa625eb708e266e06159f135e8c26f2bb7ceb72dc4b2766d0340964"
 dependencies = [
- "bitflags 2.3.3",
+ "bitflags 2.4.0",
  "errno",
  "libc",
  "linux-raw-sys",
@@ -889,12 +1370,102 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7ffc183a10b4478d04cbbbfc96d0873219d962dd5accaff2ffbd4ceb7df837f4"
 
 [[package]]
+name = "ryu"
+version = "1.0.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ad4cc8da4ef723ed60bced201181d83791ad433213d8c24efffda1eec85d741"
+
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
+[[package]]
+name = "schannel"
+version = "0.1.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c3733bf4cf7ea0880754e19cb5a462007c4a8c1914bff372ccc95b464f1df88"
+dependencies = [
+ "windows-sys",
+]
+
+[[package]]
 name = "scopeguard"
 version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
+name = "security-framework"
+version = "2.9.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05b64fb303737d99b81884b2c63433e9ae28abebe5eb5045dcdd175dc2ecf4de"
+dependencies = [
+ "bitflags 1.3.2",
+ "core-foundation",
+ "core-foundation-sys",
+ "libc",
+ "security-framework-sys",
+]
+
+[[package]]
+name = "security-framework-sys"
+version = "2.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e932934257d3b408ed8f30db49d85ea163bfe74961f017f405b025af298f0c7a"
+dependencies = [
+ "core-foundation-sys",
+ "libc",
+]
+
+[[package]]
+name = "serde"
+version = "1.0.188"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf9e0fcba69a370eed61bcf2b728575f726b50b55cba78064753d708ddc7549e"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.188"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4eca7ac642d82aa35b60049a6eccb4be6be75e599bd2e9adb5f875a737654af2"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.29",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.105"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "693151e1ac27563d6dbcec9dee9fbd5da8539b20fa14ad3752b2e6d363ace360"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "serde_urlencoded"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3491c14715ca2294c4d6a88f15e84739788c1d030eed8c110436aafdaa2f3fd"
+dependencies = [
+ "form_urlencoded",
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
 name = "signal-hook-registry"
 version = "1.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -905,9 +1476,9 @@ dependencies = [
 
 [[package]]
 name = "slab"
-version = "0.4.8"
+version = "0.4.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6528351c9bc8ab22353f9d776db39a20288e8d6c37ef8cfe3317cf875eecfc2d"
+checksum = "8f92a496fb766b417c996b9c5e57daf2f7ad3b0bebe1ccfca4856390e3d3bb67"
 dependencies = [
  "autocfg",
 ]
@@ -929,10 +1500,14 @@ dependencies = [
 ]
 
 [[package]]
-name = "static_assertions"
-version = "1.1.0"
+name = "socket2"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+checksum = "2538b18701741680e0322a2302176d3253a35388e2e62f172f64f4f16605f877"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
 
 [[package]]
 name = "strsim"
@@ -948,15 +1523,15 @@ checksum = "290d54ea6f91c969195bdbcd7442c8c2a2ba87da8bf60a7ee86a235d4bc1e125"
 
 [[package]]
 name = "strum_macros"
-version = "0.25.1"
+version = "0.25.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6069ca09d878a33f883cc06aaa9718ede171841d3832450354410b718b097232"
+checksum = "ad8d03b598d3d0fff69bf533ee3ef19b8eeb342729596df84bcc7e1f96ec4059"
 dependencies = [
  "heck",
  "proc-macro2",
  "quote",
  "rustversion",
- "syn 2.0.28",
+ "syn 2.0.29",
 ]
 
 [[package]]
@@ -972,9 +1547,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.28"
+version = "2.0.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04361975b3f5e348b2189d8dc55bc942f278b2d482a6a0365de5bdd62d351567"
+checksum = "c324c494eba9d92503e6f1ef2e6df781e78f6a7705a0202d9801b198807d518a"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -989,13 +1564,13 @@ checksum = "9d0e916b1148c8e263850e1ebcbd046f333e0683c724876bb0da63ea4373dc8a"
 
 [[package]]
 name = "tempfile"
-version = "3.7.0"
+version = "3.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5486094ee78b2e5038a6382ed7645bc084dc2ec433426ca4c3cb61e2007b8998"
+checksum = "cb94d2f3cc536af71caac6b6fcebf65860b347e7ce0cc9ebe8f70d3e521054ef"
 dependencies = [
  "cfg-if",
  "fastrand",
- "redox_syscall",
+ "redox_syscall 0.3.5",
  "rustix",
  "windows-sys",
 ]
@@ -1017,31 +1592,45 @@ checksum = "222a222a5bfe1bba4a77b45ec488a741b3cb8872e5e499451fd7d0129c9c7c3d"
 
 [[package]]
 name = "thiserror"
-version = "1.0.44"
+version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "611040a08a0439f8248d1990b111c95baa9c704c805fa1f62104b39655fd7f90"
+checksum = "97a802ec30afc17eee47b2855fc72e0c4cd62be9b4efe6591edde0ec5bd68d8f"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "1.0.44"
+version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "090198534930841fab3a5d1bb637cde49e339654e606195f8d9c76eeb081dc96"
+checksum = "6bb623b56e39ab7dcd4b1b98bb6c8f8d907ed255b18de254088016b27a8ee19b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.28",
+ "syn 2.0.29",
 ]
 
 [[package]]
+name = "tinyvec"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
+dependencies = [
+ "tinyvec_macros",
+]
+
+[[package]]
+name = "tinyvec_macros"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
+
+[[package]]
 name = "tokio"
-version = "1.29.1"
+version = "1.32.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "532826ff75199d5833b9d2c5fe410f29235e25704ee5f0ef599fb51c21f4a4da"
+checksum = "17ed6077ed6cd6c74735e21f37eb16dc3935f96878b1fe961074089cc80893f9"
 dependencies = [
- "autocfg",
  "backtrace",
  "bytes",
  "libc",
@@ -1050,7 +1639,7 @@ dependencies = [
  "parking_lot",
  "pin-project-lite",
  "signal-hook-registry",
- "socket2",
+ "socket2 0.5.3",
  "tokio-macros",
  "windows-sys",
 ]
@@ -1063,22 +1652,110 @@ checksum = "630bdcf245f78637c13ec01ffae6187cca34625e8c63150d424b59e55af2675e"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.28",
+ "syn 2.0.29",
 ]
 
 [[package]]
+name = "tokio-native-tls"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbae76ab933c85776efabc971569dd6119c580d8f5d448769dec1764bf796ef2"
+dependencies = [
+ "native-tls",
+ "tokio",
+]
+
+[[package]]
+name = "tokio-util"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "806fe8c2c87eccc8b3267cbae29ed3ab2d0bd37fca70ab622e46aaa9375ddb7d"
+dependencies = [
+ "bytes",
+ "futures-core",
+ "futures-sink",
+ "pin-project-lite",
+ "tokio",
+ "tracing",
+]
+
+[[package]]
+name = "tower-service"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6bc1c9ce2b5135ac7f93c72918fc37feb872bdc6a5533a8b85eb4b86bfdae52"
+
+[[package]]
+name = "tracing"
+version = "0.1.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ce8c33a8d48bd45d624a6e523445fd21ec13d3653cd51f681abf67418f54eb8"
+dependencies = [
+ "cfg-if",
+ "pin-project-lite",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-core"
+version = "0.1.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0955b8137a1df6f1a2e9a37d8a6656291ff0297c1a97c24e0d8425fe2312f79a"
+dependencies = [
+ "once_cell",
+]
+
+[[package]]
+name = "try-lock"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3528ecfd12c466c6f163363caf2d02a71161dd5e1cc6ae7b34207ea2d42d81ed"
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92888ba5573ff080736b3648696b70cafad7d250551175acbaa4e0385b3e1460"
+
+[[package]]
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 version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"
 
 [[package]]
+name = "unicode-normalization"
+version = "0.1.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c5713f0fc4b5db668a2ac63cdb7bb4469d8c9fed047b1d0292cc7b0ce2ba921"
+dependencies = [
+ "tinyvec",
+]
+
+[[package]]
+name = "unicode-segmentation"
+version = "1.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1dd624098567895118886609431a7c3b8f516e41d30e0643f03d94592a147e36"
+
+[[package]]
 name = "unindent"
 version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e1766d682d402817b5ac4490b3c3002d91dfa0d22812f341609f97b08757359c"
 
 [[package]]
+name = "url"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "143b538f18257fac9cad154828a57c6bf5157e1aa604d4816b5995bf6de87ae5"
+dependencies = [
+ "form_urlencoded",
+ "idna",
+ "percent-encoding",
+]
+
+[[package]]
 name = "utf8parse"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1091,12 +1768,107 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
 
 [[package]]
+name = "walkdir"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d71d857dc86794ca4c280d616f7da00d2dbfd8cd788846559a6813e6aa4b54ee"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
+[[package]]
+name = "want"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bfa7760aed19e106de2c7c0b581b509f2f25d3dacaf737cb82ac61bc6d760b0e"
+dependencies = [
+ "try-lock",
+]
+
+[[package]]
 name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
+name = "wasm-bindgen"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7706a72ab36d8cb1f80ffbf0e071533974a60d0a308d01a5d0375bf60499a342"
+dependencies = [
+ "cfg-if",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ef2b6d3c510e9625e5fe6f509ab07d66a760f0885d858736483c32ed7809abd"
+dependencies = [
+ "bumpalo",
+ "log",
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.29",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-futures"
+version = "0.4.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c02dbc21516f9f1f04f187958890d7e6026df8d16540b7ad9492bc34a67cea03"
+dependencies = [
+ "cfg-if",
+ "js-sys",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dee495e55982a3bd48105a7b947fd2a9b4a8ae3010041b9e0faab3f9cd028f1d"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54681b18a46765f095758388f2d0cf16eb8d4169b639ab575a8f5693af210c7b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.29",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.87"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca6ad05a4870b2bf5fe995117d3728437bd27d7cd5f06f13c17443ef369775a1"
+
+[[package]]
+name = "web-sys"
+version = "0.3.64"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b85cbef8c220a6abc02aefd892dfc0fc23afb1c6a426316ec33253a3877249b"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
 name = "winapi"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1138,9 +1910,9 @@ dependencies = [
 
 [[package]]
 name = "windows-targets"
-version = "0.48.1"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05d4b17490f70499f20b9e791dcf6a299785ce8af4d709018206dc5b4953e95f"
+checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
 dependencies = [
  "windows_aarch64_gnullvm",
  "windows_aarch64_msvc",
@@ -1153,42 +1925,52 @@ dependencies = [
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "91ae572e1b79dba883e0d315474df7305d12f569b400fcf90581b06062f7e1bc"
+checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2ef27e0d7bdfcfc7b868b317c1d32c641a6fe4629c171b8928c7b08d98d7cf3"
+checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "622a1962a7db830d6fd0a69683c80a18fda201879f0f447f065a3b7467daa241"
+checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4542c6e364ce21bf45d69fdd2a8e455fa38d316158cfd43b3ac1c5b1b19f8e00"
+checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ca2b8a661f7628cbd23440e50b05d705db3686f894fc9580820623656af974b1"
+checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7896dbc1f41e08872e9d5e8f8baa8fdd2677f29468c4e156210174edc7f7b953"
+checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.48.0"
+version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a515f5799fe4961cb532f983ce2b23082366b898e52ffbce459c86f67c8378a"
+checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
+
+[[package]]
+name = "winreg"
+version = "0.50.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "524e57b2c537c0f9b1e69f1965311ec12182b4122e45035b1508cd24d2adadb1"
+dependencies = [
+ "cfg-if",
+ "windows-sys",
+]
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 523074c..a553afd 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -10,12 +10,12 @@ documentation = "https://docs.rs/crate/bumble"
 authors = ["Marshall Pierce <marshallpierce@google.com>"]
 keywords = ["bluetooth", "ble"]
 categories = ["api-bindings", "network-programming"]
-rust-version = "1.69.0"
+rust-version = "1.70.0"
 
 [dependencies]
 pyo3 = { version = "0.18.3", features = ["macros"] }
 pyo3-asyncio = { version = "0.18.0", features = ["tokio-runtime"] }
-tokio = { version = "1.28.2" }
+tokio = { version = "1.28.2", features = ["macros", "signal"] }
 nom = "7.1.3"
 strum = "0.25.0"
 strum_macros = "0.25.0"
@@ -23,7 +23,21 @@ hex = "0.4.3"
 itertools = "0.11.0"
 lazy_static = "1.4.0"
 thiserror = "1.0.41"
+
+# Dev tools
+file-header = { version = "0.1.2", optional = true }
+globset = { version = "0.4.13", optional = true }
+
+# CLI
 anyhow = { version = "1.0.71", optional = true }
+clap = { version = "4.3.3", features = ["derive"], optional = true }
+directories = { version = "5.0.1", optional = true }
+env_logger = { version = "0.10.0", optional = true }
+futures = { version = "0.3.28", optional = true }
+log = { version = "0.4.19", optional = true }
+owo-colors = { version = "3.5.0", optional = true }
+reqwest = { version = "0.11.20", features = ["blocking"], optional = true }
+rusb = { version = "0.9.2", optional = true }
 
 [dev-dependencies]
 tokio = { version = "1.28.2", features = ["full"] }
@@ -32,17 +46,30 @@ nix = "0.26.2"
 anyhow = "1.0.71"
 pyo3 = { version = "0.18.3", features = ["macros", "anyhow"] }
 pyo3-asyncio = { version = "0.18.0", features = ["tokio-runtime", "attributes", "testing"] }
+rusb = "0.9.2"
+rand = "0.8.5"
 clap = { version = "4.3.3", features = ["derive"] }
 owo-colors = "3.5.0"
 log = "0.4.19"
 env_logger = "0.10.0"
-rusb = "0.9.2"
-rand = "0.8.5"
+
+[package.metadata.docs.rs]
+rustdoc-args = ["--generate-link-to-definition"]
+
+[[bin]]
+name = "file-header"
+path = "tools/file_header.rs"
+required-features = ["dev-tools"]
 
 [[bin]]
 name = "gen-assigned-numbers"
 path = "tools/gen_assigned_numbers.rs"
-required-features = ["bumble-dev-tools"]
+required-features = ["dev-tools"]
+
+[[bin]]
+name = "bumble"
+path = "src/main.rs"
+required-features = ["bumble-tools"]
 
 # test entry point that uses pyo3_asyncio's test harness
 [[test]]
@@ -53,4 +80,7 @@ harness = false
 [features]
 anyhow = ["pyo3/anyhow"]
 pyo3-asyncio-attributes = ["pyo3-asyncio/attributes"]
-bumble-dev-tools = ["dep:anyhow"]
\ No newline at end of file
+dev-tools = ["dep:anyhow", "dep:clap", "dep:file-header", "dep:globset"]
+# separate feature for CLI so that dependencies don't spend time building these
+bumble-tools = ["dep:clap", "anyhow", "dep:anyhow", "dep:directories", "pyo3-asyncio-attributes", "dep:owo-colors", "dep:reqwest", "dep:rusb", "dep:log", "dep:env_logger", "dep:futures"]
+default = []
diff --git a/rust/README.md b/rust/README.md
index 2684875..15a19b9 100644
--- a/rust/README.md
+++ b/rust/README.md
@@ -5,7 +5,8 @@ Rust wrappers around the [Bumble](https://github.com/google/bumble) Python API.
 Method calls are mapped to the equivalent Python, and return types adapted where
 relevant.
 
-See the `examples` directory for usage.
+See the CLI in `src/main.rs` or the `examples` directory for how to use the
+Bumble API.
 
 # Usage
 
@@ -27,6 +28,15 @@ PYTHONPATH=..:~/.virtualenvs/bumble/lib/python3.10/site-packages/ \
 Run the corresponding `battery_server` Python example, and launch an emulator in
 Android Studio (currently, Canary is required) to run netsim.
 
+# CLI
+
+Explore the available subcommands:
+
+```
+PYTHONPATH=..:[virtualenv site-packages] \
+    cargo run --features bumble-tools --bin bumble -- --help
+```
+
 # Development
 
 Run the tests:
@@ -43,7 +53,7 @@ cargo clippy --all-targets
 
 ## Code gen
 
-To have the fastest startup while keeping the build simple, code gen for 
+To have the fastest startup while keeping the build simple, code gen for
 assigned numbers is done with the `gen_assigned_numbers` tool. It should
 be re-run whenever the Python assigned numbers are changed. To ensure that the
 generated code is kept up to date, the Rust data is compared to the Python
@@ -52,5 +62,5 @@ in tests at `pytests/assigned_numbers.rs`.
 To regenerate the assigned number tables based on the Python codebase:
 
 ```
-PYTHONPATH=.. cargo run --bin gen-assigned-numbers --features bumble-dev-tools
+PYTHONPATH=.. cargo run --bin gen-assigned-numbers --features dev-tools
 ```
\ No newline at end of file
diff --git a/rust/pytests/assigned_numbers.rs b/rust/pytests/assigned_numbers.rs
index 10e7f3e..7f8f1d1 100644
--- a/rust/pytests/assigned_numbers.rs
+++ b/rust/pytests/assigned_numbers.rs
@@ -1,3 +1,17 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 use bumble::wrapper::{self, core::Uuid16};
 use pyo3::{intern, prelude::*, types::PyDict};
 use std::collections;
diff --git a/rust/pytests/wrapper.rs b/rust/pytests/wrapper.rs
index 333005b..8f69dd7 100644
--- a/rust/pytests/wrapper.rs
+++ b/rust/pytests/wrapper.rs
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use bumble::wrapper::transport::Transport;
+use bumble::wrapper::{drivers::rtk::DriverInfo, transport::Transport};
 use nix::sys::stat::Mode;
 use pyo3::PyResult;
 
@@ -29,3 +29,9 @@ async fn fifo_transport_can_open() -> PyResult<()> {
 
     Ok(())
 }
+
+#[pyo3_asyncio::tokio::test]
+async fn realtek_driver_info_all_drivers() -> PyResult<()> {
+    assert_eq!(12, DriverInfo::all_drivers()?.len());
+    Ok(())
+}
diff --git a/rust/resources/test/firmware/realtek/README.md b/rust/resources/test/firmware/realtek/README.md
new file mode 100644
index 0000000..4c49608
--- /dev/null
+++ b/rust/resources/test/firmware/realtek/README.md
@@ -0,0 +1,4 @@
+This dir contains samples firmware images in the format used for Realtek chips,
+but with repetitions of the length of the section as a little-endian 32-bit int
+for the patch data instead of actual firmware, since we only need the structure
+to test parsing.
\ No newline at end of file
diff --git a/rust/resources/test/firmware/realtek/rtl8723b_fw_structure.bin b/rust/resources/test/firmware/realtek/rtl8723b_fw_structure.bin
new file mode 100644
index 0000000..077cdc3
--- /dev/null
+++ b/rust/resources/test/firmware/realtek/rtl8723b_fw_structure.bin
diff --git a/rust/resources/test/firmware/realtek/rtl8761bu_fw_structure.bin b/rust/resources/test/firmware/realtek/rtl8761bu_fw_structure.bin
new file mode 100644
index 0000000..94df0ba
--- /dev/null
+++ b/rust/resources/test/firmware/realtek/rtl8761bu_fw_structure.bin
diff --git a/rust/src/adv.rs b/rust/src/adv.rs
index 8a4c979..6f84cc5 100644
--- a/rust/src/adv.rs
+++ b/rust/src/adv.rs
@@ -1,3 +1,17 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 //! BLE advertisements.
 
 use crate::wrapper::assigned_numbers::{COMPANY_IDS, SERVICE_IDS};
diff --git a/rust/src/cli/firmware/mod.rs b/rust/src/cli/firmware/mod.rs
new file mode 100644
index 0000000..1fa1417
--- /dev/null
+++ b/rust/src/cli/firmware/mod.rs
@@ -0,0 +1,15 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub(crate) mod rtk;
diff --git a/rust/src/cli/firmware/rtk.rs b/rust/src/cli/firmware/rtk.rs
new file mode 100644
index 0000000..f5524a4
--- /dev/null
+++ b/rust/src/cli/firmware/rtk.rs
@@ -0,0 +1,265 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Realtek firmware tools
+
+use crate::{Download, Source};
+use anyhow::anyhow;
+use bumble::wrapper::{
+    drivers::rtk::{Driver, DriverInfo, Firmware},
+    host::{DriverFactory, Host},
+    transport::Transport,
+};
+use owo_colors::{colors::css, OwoColorize};
+use pyo3::PyResult;
+use std::{fs, path};
+
+pub(crate) async fn download(dl: Download) -> PyResult<()> {
+    let data_dir = dl
+        .output_dir
+        .or_else(|| {
+            directories::ProjectDirs::from("com", "google", "bumble")
+                .map(|pd| pd.data_local_dir().join("firmware").join("realtek"))
+        })
+        .unwrap_or_else(|| {
+            eprintln!("Could not determine standard data directory");
+            path::PathBuf::from(".")
+        });
+    fs::create_dir_all(&data_dir)?;
+
+    let (base_url, uses_bin_suffix) = match dl.source {
+        Source::LinuxKernel => ("https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/rtl_bt", true),
+        Source::RealtekOpensource => ("https://github.com/Realtek-OpenSource/android_hardware_realtek/raw/rtk1395/bt/rtkbt/Firmware/BT", false),
+        Source::LinuxFromScratch => ("https://anduin.linuxfromscratch.org/sources/linux-firmware/rtl_bt", true),
+    };
+
+    println!("Downloading");
+    println!("{} {}", "FROM:".green(), base_url);
+    println!("{} {}", "TO:".green(), data_dir.to_string_lossy());
+
+    let url_for_file = |file_name: &str| {
+        let url_suffix = if uses_bin_suffix {
+            file_name
+        } else {
+            file_name.trim_end_matches(".bin")
+        };
+
+        let mut url = base_url.to_string();
+        url.push('/');
+        url.push_str(url_suffix);
+        url
+    };
+
+    let to_download = if let Some(single) = dl.single {
+        vec![(
+            format!("{single}_fw.bin"),
+            Some(format!("{single}_config.bin")),
+            false,
+        )]
+    } else {
+        DriverInfo::all_drivers()?
+            .iter()
+            .map(|di| Ok((di.firmware_name()?, di.config_name()?, di.config_needed()?)))
+            .collect::<PyResult<Vec<_>>>()?
+    };
+
+    let client = SimpleClient::new();
+
+    for (fw_filename, config_filename, config_needed) in to_download {
+        println!("{}", "---".yellow());
+        let fw_path = data_dir.join(&fw_filename);
+        let config_path = config_filename.as_ref().map(|f| data_dir.join(f));
+
+        if fw_path.exists() && !dl.overwrite {
+            println!(
+                "{}",
+                format!("{} already exists, skipping", fw_path.to_string_lossy())
+                    .fg::<css::Orange>()
+            );
+            continue;
+        }
+        if let Some(cp) = config_path.as_ref() {
+            if cp.exists() && !dl.overwrite {
+                println!(
+                    "{}",
+                    format!("{} already exists, skipping", cp.to_string_lossy())
+                        .fg::<css::Orange>()
+                );
+                continue;
+            }
+        }
+
+        let fw_contents = match client.get(&url_for_file(&fw_filename)).await {
+            Ok(data) => {
+                println!("Downloaded {}: {} bytes", fw_filename, data.len());
+                data
+            }
+            Err(e) => {
+                eprintln!(
+                    "{} {} {:?}",
+                    "Failed to download".red(),
+                    fw_filename.red(),
+                    e
+                );
+                continue;
+            }
+        };
+
+        let config_contents = if let Some(cn) = &config_filename {
+            match client.get(&url_for_file(cn)).await {
+                Ok(data) => {
+                    println!("Downloaded {}: {} bytes", cn, data.len());
+                    Some(data)
+                }
+                Err(e) => {
+                    if config_needed {
+                        eprintln!("{} {} {:?}", "Failed to download".red(), cn.red(), e);
+                        continue;
+                    } else {
+                        eprintln!(
+                            "{}",
+                            format!("No config available as {cn}").fg::<css::Orange>()
+                        );
+                        None
+                    }
+                }
+            }
+        } else {
+            None
+        };
+
+        fs::write(&fw_path, &fw_contents)?;
+        if !dl.no_parse && config_filename.is_some() {
+            println!("{} {}", "Parsing:".cyan(), &fw_filename);
+            match Firmware::parse(&fw_contents).map_err(|e| anyhow!("Parse error: {:?}", e)) {
+                Ok(fw) => dump_firmware_desc(&fw),
+                Err(e) => {
+                    eprintln!(
+                        "{} {:?}",
+                        "Could not parse firmware:".fg::<css::Orange>(),
+                        e
+                    );
+                }
+            }
+        }
+        if let Some((cp, cd)) = config_path
+            .as_ref()
+            .and_then(|p| config_contents.map(|c| (p, c)))
+        {
+            fs::write(cp, &cd)?;
+        }
+    }
+
+    Ok(())
+}
+
+pub(crate) fn parse(firmware_path: &path::Path) -> PyResult<()> {
+    let contents = fs::read(firmware_path)?;
+    let fw = Firmware::parse(&contents)
+        // squish the error into a string to avoid the error type requiring that the input be
+        // 'static
+        .map_err(|e| anyhow!("Parse error: {:?}", e))?;
+
+    dump_firmware_desc(&fw);
+
+    Ok(())
+}
+
+pub(crate) async fn info(transport: &str, force: bool) -> PyResult<()> {
+    let transport = Transport::open(transport).await?;
+
+    let mut host = Host::new(transport.source()?, transport.sink()?)?;
+    host.reset(DriverFactory::None).await?;
+
+    if !force && !Driver::check(&host).await? {
+        println!("USB device not supported by this RTK driver");
+    } else if let Some(driver_info) = Driver::driver_info_for_host(&host).await? {
+        println!("Driver:");
+        println!("  {:10} {:04X}", "ROM:", driver_info.rom()?);
+        println!("  {:10} {}", "Firmware:", driver_info.firmware_name()?);
+        println!(
+            "  {:10} {}",
+            "Config:",
+            driver_info.config_name()?.unwrap_or_default()
+        );
+    } else {
+        println!("Firmware already loaded or no supported driver for this device.")
+    }
+
+    Ok(())
+}
+
+pub(crate) async fn load(transport: &str, force: bool) -> PyResult<()> {
+    let transport = Transport::open(transport).await?;
+
+    let mut host = Host::new(transport.source()?, transport.sink()?)?;
+    host.reset(DriverFactory::None).await?;
+
+    match Driver::for_host(&host, force).await? {
+        None => {
+            eprintln!("Firmware already loaded or no supported driver for this device.");
+        }
+        Some(mut d) => d.download_firmware().await?,
+    };
+
+    Ok(())
+}
+
+pub(crate) async fn drop(transport: &str) -> PyResult<()> {
+    let transport = Transport::open(transport).await?;
+
+    let mut host = Host::new(transport.source()?, transport.sink()?)?;
+    host.reset(DriverFactory::None).await?;
+
+    Driver::drop_firmware(&mut host).await?;
+
+    Ok(())
+}
+
+fn dump_firmware_desc(fw: &Firmware) {
+    println!(
+        "Firmware: version=0x{:08X} project_id=0x{:04X}",
+        fw.version(),
+        fw.project_id()
+    );
+    for p in fw.patches() {
+        println!(
+            "  Patch: chip_id=0x{:04X}, {} bytes, SVN Version={:08X}",
+            p.chip_id(),
+            p.contents().len(),
+            p.svn_version()
+        )
+    }
+}
+
+struct SimpleClient {
+    client: reqwest::Client,
+}
+
+impl SimpleClient {
+    fn new() -> Self {
+        Self {
+            client: reqwest::Client::new(),
+        }
+    }
+
+    async fn get(&self, url: &str) -> anyhow::Result<Vec<u8>> {
+        let resp = self.client.get(url).send().await?;
+        if !resp.status().is_success() {
+            return Err(anyhow!("Bad status: {}", resp.status()));
+        }
+        let bytes = resp.bytes().await?;
+        Ok(bytes.as_ref().to_vec())
+    }
+}
diff --git a/rust/src/cli/l2cap/client_bridge.rs b/rust/src/cli/l2cap/client_bridge.rs
new file mode 100644
index 0000000..37606fc
--- /dev/null
+++ b/rust/src/cli/l2cap/client_bridge.rs
@@ -0,0 +1,191 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// L2CAP CoC client bridge: connects to a BLE device, then waits for an inbound
+/// TCP connection on a specified port number. When a TCP client connects, an
+/// L2CAP CoC channel connection to the BLE device is established, and the data
+/// is bridged in both directions, with flow control.
+/// When the TCP connection is closed by the client, the L2CAP CoC channel is
+/// disconnected, but the connection to the BLE device remains, ready for a new
+/// TCP client to connect.
+/// When the L2CAP CoC channel is closed, the TCP connection is closed as well.
+use crate::cli::l2cap::{
+    proxy_l2cap_rx_to_tcp_tx, proxy_tcp_rx_to_l2cap_tx, run_future_with_current_task_locals,
+    BridgeData,
+};
+use bumble::wrapper::{
+    device::{Connection, Device},
+    hci::HciConstant,
+};
+use futures::executor::block_on;
+use owo_colors::OwoColorize;
+use pyo3::{PyResult, Python};
+use std::{net::SocketAddr, sync::Arc};
+use tokio::{
+    join,
+    net::{TcpListener, TcpStream},
+    sync::{mpsc, Mutex},
+};
+
+pub struct Args {
+    pub psm: u16,
+    pub max_credits: Option<u16>,
+    pub mtu: Option<u16>,
+    pub mps: Option<u16>,
+    pub bluetooth_address: String,
+    pub tcp_host: String,
+    pub tcp_port: u16,
+}
+
+pub async fn start(args: &Args, device: &mut Device) -> PyResult<()> {
+    println!(
+        "{}",
+        format!("### Connecting to {}...", args.bluetooth_address).yellow()
+    );
+    let mut ble_connection = device.connect(&args.bluetooth_address).await?;
+    ble_connection.on_disconnection(|_py, reason| {
+        let disconnection_info = match HciConstant::error_name(reason) {
+            Ok(info_string) => info_string,
+            Err(py_err) => format!("failed to get disconnection error name ({})", py_err),
+        };
+        println!(
+            "{} {}",
+            "@@@ Bluetooth disconnection: ".red(),
+            disconnection_info,
+        );
+        Ok(())
+    })?;
+
+    // Start the TCP server.
+    let listener = TcpListener::bind(format!("{}:{}", args.tcp_host, args.tcp_port))
+        .await
+        .expect("failed to bind tcp to address");
+    println!(
+        "{}",
+        format!(
+            "### Listening for TCP connections on port {}",
+            args.tcp_port
+        )
+        .magenta()
+    );
+
+    let psm = args.psm;
+    let max_credits = args.max_credits;
+    let mtu = args.mtu;
+    let mps = args.mps;
+    let ble_connection = Arc::new(Mutex::new(ble_connection));
+    // Ensure Python event loop is available to l2cap `disconnect`
+    let _ = run_future_with_current_task_locals(async move {
+        while let Ok((tcp_stream, addr)) = listener.accept().await {
+            let ble_connection = ble_connection.clone();
+            let _ = run_future_with_current_task_locals(proxy_data_between_tcp_and_l2cap(
+                ble_connection,
+                tcp_stream,
+                addr,
+                psm,
+                max_credits,
+                mtu,
+                mps,
+            ));
+        }
+        Ok(())
+    });
+    Ok(())
+}
+
+async fn proxy_data_between_tcp_and_l2cap(
+    ble_connection: Arc<Mutex<Connection>>,
+    tcp_stream: TcpStream,
+    addr: SocketAddr,
+    psm: u16,
+    max_credits: Option<u16>,
+    mtu: Option<u16>,
+    mps: Option<u16>,
+) -> PyResult<()> {
+    println!("{}", format!("<<< TCP connection from {}", addr).magenta());
+    println!(
+        "{}",
+        format!(">>> Opening L2CAP channel on PSM = {}", psm).yellow()
+    );
+
+    let mut l2cap_channel = match ble_connection
+        .lock()
+        .await
+        .open_l2cap_channel(psm, max_credits, mtu, mps)
+        .await
+    {
+        Ok(channel) => channel,
+        Err(e) => {
+            println!("{}", format!("!!! Connection failed: {e}").red());
+            // TCP stream will get dropped after returning, automatically shutting it down.
+            return Err(e);
+        }
+    };
+    let channel_info = l2cap_channel
+        .debug_string()
+        .unwrap_or_else(|e| format!("failed to get l2cap channel info ({e})"));
+
+    println!("{}{}", "*** L2CAP channel: ".cyan(), channel_info);
+
+    let (l2cap_to_tcp_tx, l2cap_to_tcp_rx) = mpsc::channel::<BridgeData>(10);
+
+    // Set l2cap callback (`set_sink`) for when data is received.
+    let l2cap_to_tcp_tx_clone = l2cap_to_tcp_tx.clone();
+    l2cap_channel
+        .set_sink(move |_py, sdu| {
+            block_on(l2cap_to_tcp_tx_clone.send(BridgeData::Data(sdu.into())))
+                .expect("failed to channel data to tcp");
+            Ok(())
+        })
+        .expect("failed to set sink for l2cap connection");
+
+    // Set l2cap callback for when the channel is closed.
+    l2cap_channel
+        .on_close(move |_py| {
+            println!("{}", "*** L2CAP channel closed".red());
+            block_on(l2cap_to_tcp_tx.send(BridgeData::CloseSignal))
+                .expect("failed to channel close signal to tcp");
+            Ok(())
+        })
+        .expect("failed to set on_close callback for l2cap channel");
+
+    let l2cap_channel = Arc::new(Mutex::new(Some(l2cap_channel)));
+    let (tcp_reader, tcp_writer) = tcp_stream.into_split();
+
+    // Do tcp stuff when something happens on the l2cap channel.
+    let handle_l2cap_data_future =
+        proxy_l2cap_rx_to_tcp_tx(l2cap_to_tcp_rx, tcp_writer, l2cap_channel.clone());
+
+    // Do l2cap stuff when something happens on tcp.
+    let handle_tcp_data_future = proxy_tcp_rx_to_l2cap_tx(tcp_reader, l2cap_channel.clone(), true);
+
+    let (handle_l2cap_result, handle_tcp_result) =
+        join!(handle_l2cap_data_future, handle_tcp_data_future);
+
+    if let Err(e) = handle_l2cap_result {
+        println!("!!! Error: {e}");
+    }
+
+    if let Err(e) = handle_tcp_result {
+        println!("!!! Error: {e}");
+    }
+
+    Python::with_gil(|_| {
+        // Must hold GIL at least once while/after dropping for Python heap object to ensure
+        // de-allocation.
+        drop(l2cap_channel);
+    });
+
+    Ok(())
+}
diff --git a/rust/src/cli/l2cap/mod.rs b/rust/src/cli/l2cap/mod.rs
new file mode 100644
index 0000000..31097ed
--- /dev/null
+++ b/rust/src/cli/l2cap/mod.rs
@@ -0,0 +1,190 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Rust version of the Python `l2cap_bridge.py` found under the `apps` folder.
+
+use crate::L2cap;
+use anyhow::anyhow;
+use bumble::wrapper::{device::Device, l2cap::LeConnectionOrientedChannel, transport::Transport};
+use owo_colors::{colors::css::Orange, OwoColorize};
+use pyo3::{PyObject, PyResult, Python};
+use std::{future::Future, path::PathBuf, sync::Arc};
+use tokio::{
+    io::{AsyncReadExt, AsyncWriteExt},
+    net::tcp::{OwnedReadHalf, OwnedWriteHalf},
+    sync::{mpsc::Receiver, Mutex},
+};
+
+mod client_bridge;
+mod server_bridge;
+
+pub(crate) async fn run(
+    command: L2cap,
+    device_config: PathBuf,
+    transport: String,
+    psm: u16,
+    max_credits: Option<u16>,
+    mtu: Option<u16>,
+    mps: Option<u16>,
+) -> PyResult<()> {
+    println!("<<< connecting to HCI...");
+    let transport = Transport::open(transport).await?;
+    println!("<<< connected");
+
+    let mut device =
+        Device::from_config_file_with_hci(&device_config, transport.source()?, transport.sink()?)?;
+
+    device.power_on().await?;
+
+    match command {
+        L2cap::Server { tcp_host, tcp_port } => {
+            let args = server_bridge::Args {
+                psm,
+                max_credits,
+                mtu,
+                mps,
+                tcp_host,
+                tcp_port,
+            };
+
+            server_bridge::start(&args, &mut device).await?
+        }
+        L2cap::Client {
+            bluetooth_address,
+            tcp_host,
+            tcp_port,
+        } => {
+            let args = client_bridge::Args {
+                psm,
+                max_credits,
+                mtu,
+                mps,
+                bluetooth_address,
+                tcp_host,
+                tcp_port,
+            };
+
+            client_bridge::start(&args, &mut device).await?
+        }
+    };
+
+    // wait until user kills the process
+    tokio::signal::ctrl_c().await?;
+
+    Ok(())
+}
+
+/// Used for channeling data from Python callbacks to a Rust consumer.
+enum BridgeData {
+    Data(Vec<u8>),
+    CloseSignal,
+}
+
+async fn proxy_l2cap_rx_to_tcp_tx(
+    mut l2cap_data_receiver: Receiver<BridgeData>,
+    mut tcp_writer: OwnedWriteHalf,
+    l2cap_channel: Arc<Mutex<Option<LeConnectionOrientedChannel>>>,
+) -> anyhow::Result<()> {
+    while let Some(bridge_data) = l2cap_data_receiver.recv().await {
+        match bridge_data {
+            BridgeData::Data(sdu) => {
+                println!("{}", format!("<<< [L2CAP SDU]: {} bytes", sdu.len()).cyan());
+                tcp_writer
+                    .write_all(sdu.as_ref())
+                    .await
+                    .map_err(|_| anyhow!("Failed to write to tcp stream"))?;
+                tcp_writer
+                    .flush()
+                    .await
+                    .map_err(|_| anyhow!("Failed to flush tcp stream"))?;
+            }
+            BridgeData::CloseSignal => {
+                l2cap_channel.lock().await.take();
+                tcp_writer
+                    .shutdown()
+                    .await
+                    .map_err(|_| anyhow!("Failed to shut down write half of tcp stream"))?;
+                return Ok(());
+            }
+        }
+    }
+    Ok(())
+}
+
+async fn proxy_tcp_rx_to_l2cap_tx(
+    mut tcp_reader: OwnedReadHalf,
+    l2cap_channel: Arc<Mutex<Option<LeConnectionOrientedChannel>>>,
+    drain_l2cap_after_write: bool,
+) -> PyResult<()> {
+    let mut buf = [0; 4096];
+    loop {
+        match tcp_reader.read(&mut buf).await {
+            Ok(len) => {
+                if len == 0 {
+                    println!("{}", "!!! End of stream".fg::<Orange>());
+
+                    if let Some(mut channel) = l2cap_channel.lock().await.take() {
+                        channel.disconnect().await.map_err(|e| {
+                            eprintln!("Failed to call disconnect on l2cap channel: {e}");
+                            e
+                        })?;
+                    }
+                    return Ok(());
+                }
+
+                println!("{}", format!("<<< [TCP DATA]: {len} bytes").blue());
+                match l2cap_channel.lock().await.as_mut() {
+                    None => {
+                        println!("{}", "!!! L2CAP channel not connected, dropping".red());
+                        return Ok(());
+                    }
+                    Some(channel) => {
+                        channel.write(&buf[..len])?;
+                        if drain_l2cap_after_write {
+                            channel.drain().await?;
+                        }
+                    }
+                }
+            }
+            Err(e) => {
+                println!("{}", format!("!!! TCP connection lost: {}", e).red());
+                if let Some(mut channel) = l2cap_channel.lock().await.take() {
+                    let _ = channel.disconnect().await.map_err(|e| {
+                        eprintln!("Failed to call disconnect on l2cap channel: {e}");
+                    });
+                }
+                return Err(e.into());
+            }
+        }
+    }
+}
+
+/// Copies the current thread's TaskLocals into a Python "awaitable" and encapsulates it in a Rust
+/// future, running it as a Python Task.
+/// `TaskLocals` stores the current event loop, and allows the user to copy the current Python
+/// context if necessary. In this case, the python event loop is used when calling `disconnect` on
+/// an l2cap connection, or else the call will fail.
+pub fn run_future_with_current_task_locals<F>(
+    fut: F,
+) -> PyResult<impl Future<Output = PyResult<PyObject>> + Send>
+where
+    F: Future<Output = PyResult<()>> + Send + 'static,
+{
+    Python::with_gil(|py| {
+        let locals = pyo3_asyncio::tokio::get_current_locals(py)?;
+        let future = pyo3_asyncio::tokio::scope(locals.clone(), fut);
+        pyo3_asyncio::tokio::future_into_py_with_locals(py, locals, future)
+            .and_then(pyo3_asyncio::tokio::into_future)
+    })
+}
diff --git a/rust/src/cli/l2cap/server_bridge.rs b/rust/src/cli/l2cap/server_bridge.rs
new file mode 100644
index 0000000..3a32db9
--- /dev/null
+++ b/rust/src/cli/l2cap/server_bridge.rs
@@ -0,0 +1,205 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// L2CAP CoC server bridge: waits for a peer to connect an L2CAP CoC channel
+/// on a specified PSM. When the connection is made, the bridge connects a TCP
+/// socket to a remote host and bridges the data in both directions, with flow
+/// control.
+/// When the L2CAP CoC channel is closed, the bridge disconnects the TCP socket
+/// and waits for a new L2CAP CoC channel to be connected.
+/// When the TCP connection is closed by the TCP server, the L2CAP connection is closed as well.
+use crate::cli::l2cap::{
+    proxy_l2cap_rx_to_tcp_tx, proxy_tcp_rx_to_l2cap_tx, run_future_with_current_task_locals,
+    BridgeData,
+};
+use bumble::wrapper::{device::Device, hci::HciConstant, l2cap::LeConnectionOrientedChannel};
+use futures::executor::block_on;
+use owo_colors::OwoColorize;
+use pyo3::{PyResult, Python};
+use std::{sync::Arc, time::Duration};
+use tokio::{
+    join,
+    net::TcpStream,
+    select,
+    sync::{mpsc, Mutex},
+};
+
+pub struct Args {
+    pub psm: u16,
+    pub max_credits: Option<u16>,
+    pub mtu: Option<u16>,
+    pub mps: Option<u16>,
+    pub tcp_host: String,
+    pub tcp_port: u16,
+}
+
+pub async fn start(args: &Args, device: &mut Device) -> PyResult<()> {
+    let host = args.tcp_host.clone();
+    let port = args.tcp_port;
+    device.register_l2cap_channel_server(
+        args.psm,
+        move |_py, l2cap_channel| {
+            let channel_info = l2cap_channel
+                .debug_string()
+                .unwrap_or_else(|e| format!("failed to get l2cap channel info ({e})"));
+            println!("{} {channel_info}", "*** L2CAP channel:".cyan());
+
+            let host = host.clone();
+            // Ensure Python event loop is available to l2cap `disconnect`
+            let _ = run_future_with_current_task_locals(proxy_data_between_l2cap_and_tcp(
+                l2cap_channel,
+                host,
+                port,
+            ));
+            Ok(())
+        },
+        args.max_credits,
+        args.mtu,
+        args.mps,
+    )?;
+
+    println!(
+        "{}",
+        format!("### Listening for CoC connection on PSM {}", args.psm).yellow()
+    );
+
+    device.on_connection(|_py, mut connection| {
+        let connection_info = connection
+            .debug_string()
+            .unwrap_or_else(|e| format!("failed to get connection info ({e})"));
+        println!(
+            "{} {}",
+            "@@@ Bluetooth connection: ".green(),
+            connection_info,
+        );
+        connection.on_disconnection(|_py, reason| {
+            let disconnection_info = match HciConstant::error_name(reason) {
+                Ok(info_string) => info_string,
+                Err(py_err) => format!("failed to get disconnection error name ({})", py_err),
+            };
+            println!(
+                "{} {}",
+                "@@@ Bluetooth disconnection: ".red(),
+                disconnection_info,
+            );
+            Ok(())
+        })?;
+        Ok(())
+    })?;
+
+    device.start_advertising(false).await?;
+
+    Ok(())
+}
+
+async fn proxy_data_between_l2cap_and_tcp(
+    mut l2cap_channel: LeConnectionOrientedChannel,
+    tcp_host: String,
+    tcp_port: u16,
+) -> PyResult<()> {
+    let (l2cap_to_tcp_tx, mut l2cap_to_tcp_rx) = mpsc::channel::<BridgeData>(10);
+
+    // Set callback (`set_sink`) for when l2cap data is received.
+    let l2cap_to_tcp_tx_clone = l2cap_to_tcp_tx.clone();
+    l2cap_channel
+        .set_sink(move |_py, sdu| {
+            block_on(l2cap_to_tcp_tx_clone.send(BridgeData::Data(sdu.into())))
+                .expect("failed to channel data to tcp");
+            Ok(())
+        })
+        .expect("failed to set sink for l2cap connection");
+
+    // Set l2cap callback for when the channel is closed.
+    l2cap_channel
+        .on_close(move |_py| {
+            println!("{}", "*** L2CAP channel closed".red());
+            block_on(l2cap_to_tcp_tx.send(BridgeData::CloseSignal))
+                .expect("failed to channel close signal to tcp");
+            Ok(())
+        })
+        .expect("failed to set on_close callback for l2cap channel");
+
+    println!(
+        "{}",
+        format!("### Connecting to TCP {tcp_host}:{tcp_port}...").yellow()
+    );
+
+    let l2cap_channel = Arc::new(Mutex::new(Some(l2cap_channel)));
+    let tcp_stream = match TcpStream::connect(format!("{tcp_host}:{tcp_port}")).await {
+        Ok(stream) => {
+            println!("{}", "### Connected".green());
+            Some(stream)
+        }
+        Err(err) => {
+            println!("{}", format!("!!! Connection failed: {err}").red());
+            if let Some(mut channel) = l2cap_channel.lock().await.take() {
+                // Bumble might enter an invalid state if disconnection request is received from
+                // l2cap client before receiving a disconnection response from the same client,
+                // blocking this async call from returning.
+                // See: https://github.com/google/bumble/issues/257
+                select! {
+                    res = channel.disconnect() => {
+                        let _ = res.map_err(|e| eprintln!("Failed to call disconnect on l2cap channel: {e}"));
+                    },
+                    _ = tokio::time::sleep(Duration::from_secs(1)) => eprintln!("Timed out while calling disconnect on l2cap channel."),
+                }
+            }
+            None
+        }
+    };
+
+    match tcp_stream {
+        None => {
+            while let Some(bridge_data) = l2cap_to_tcp_rx.recv().await {
+                match bridge_data {
+                    BridgeData::Data(sdu) => {
+                        println!("{}", format!("<<< [L2CAP SDU]: {} bytes", sdu.len()).cyan());
+                        println!("{}", "!!! TCP socket not open, dropping".red())
+                    }
+                    BridgeData::CloseSignal => break,
+                }
+            }
+        }
+        Some(tcp_stream) => {
+            let (tcp_reader, tcp_writer) = tcp_stream.into_split();
+
+            // Do tcp stuff when something happens on the l2cap channel.
+            let handle_l2cap_data_future =
+                proxy_l2cap_rx_to_tcp_tx(l2cap_to_tcp_rx, tcp_writer, l2cap_channel.clone());
+
+            // Do l2cap stuff when something happens on tcp.
+            let handle_tcp_data_future =
+                proxy_tcp_rx_to_l2cap_tx(tcp_reader, l2cap_channel.clone(), false);
+
+            let (handle_l2cap_result, handle_tcp_result) =
+                join!(handle_l2cap_data_future, handle_tcp_data_future);
+
+            if let Err(e) = handle_l2cap_result {
+                println!("!!! Error: {e}");
+            }
+
+            if let Err(e) = handle_tcp_result {
+                println!("!!! Error: {e}");
+            }
+        }
+    };
+
+    Python::with_gil(|_| {
+        // Must hold GIL at least once while/after dropping for Python heap object to ensure
+        // de-allocation.
+        drop(l2cap_channel);
+    });
+
+    Ok(())
+}
diff --git a/rust/src/cli/mod.rs b/rust/src/cli/mod.rs
new file mode 100644
index 0000000..e58f88c
--- /dev/null
+++ b/rust/src/cli/mod.rs
@@ -0,0 +1,19 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub(crate) mod firmware;
+
+pub(crate) mod usb;
+
+pub(crate) mod l2cap;
diff --git a/rust/examples/usb_probe.rs b/rust/src/cli/usb/mod.rs
index 3ba3b61..7adbd75 100644
--- a/rust/examples/usb_probe.rs
+++ b/rust/src/cli/usb/mod.rs
@@ -23,7 +23,6 @@
 //! whether it is a Bluetooth device that uses a non-standard Class, or some other
 //! type of device (there's no way to tell).
 
-use clap::Parser as _;
 use itertools::Itertools as _;
 use owo_colors::{OwoColorize, Style};
 use rusb::{Device, DeviceDescriptor, Direction, TransferType, UsbContext};
@@ -31,15 +30,12 @@ use std::{
     collections::{HashMap, HashSet},
     time::Duration,
 };
-
 const USB_DEVICE_CLASS_DEVICE: u8 = 0x00;
 const USB_DEVICE_CLASS_WIRELESS_CONTROLLER: u8 = 0xE0;
 const USB_DEVICE_SUBCLASS_RF_CONTROLLER: u8 = 0x01;
 const USB_DEVICE_PROTOCOL_BLUETOOTH_PRIMARY_CONTROLLER: u8 = 0x01;
 
-fn main() -> anyhow::Result<()> {
-    let cli = Cli::parse();
-
+pub(crate) fn probe(verbose: bool) -> anyhow::Result<()> {
     let mut bt_dev_count = 0;
     let mut device_serials_by_id: HashMap<(u16, u16), HashSet<String>> = HashMap::new();
     for device in rusb::devices()?.iter() {
@@ -159,7 +155,7 @@ fn main() -> anyhow::Result<()> {
             println!("{:26}{}", "  Product:".green(), p);
         }
 
-        if cli.verbose {
+        if verbose {
             print_device_details(&device, &device_desc)?;
         }
 
@@ -332,11 +328,3 @@ impl From<&DeviceDescriptor> for ClassInfo {
         )
     }
 }
-
-#[derive(clap::Parser)]
-#[command(author, version, about, long_about = None)]
-struct Cli {
-    /// Show additional info for each USB device
-    #[arg(long, default_value_t = false)]
-    verbose: bool,
-}
diff --git a/rust/src/internal/drivers/mod.rs b/rust/src/internal/drivers/mod.rs
new file mode 100644
index 0000000..5e72c59
--- /dev/null
+++ b/rust/src/internal/drivers/mod.rs
@@ -0,0 +1,17 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Device drivers
+
+pub(crate) mod rtk;
diff --git a/rust/src/internal/drivers/rtk.rs b/rust/src/internal/drivers/rtk.rs
new file mode 100644
index 0000000..2d4e685
--- /dev/null
+++ b/rust/src/internal/drivers/rtk.rs
@@ -0,0 +1,253 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Drivers for Realtek controllers
+
+use nom::{bytes, combinator, error, multi, number, sequence};
+
+/// Realtek firmware file contents
+pub struct Firmware {
+    version: u32,
+    project_id: u8,
+    patches: Vec<Patch>,
+}
+
+impl Firmware {
+    /// Parse a `*_fw.bin` file
+    pub fn parse(input: &[u8]) -> Result<Self, nom::Err<error::Error<&[u8]>>> {
+        let extension_sig = [0x51, 0x04, 0xFD, 0x77];
+
+        let (_rem, (_tag, fw_version, patch_count, payload)) =
+            combinator::all_consuming(combinator::map_parser(
+                // ignore the sig suffix
+                sequence::terminated(
+                    bytes::complete::take(
+                        // underflow will show up as parse failure
+                        input.len().saturating_sub(extension_sig.len()),
+                    ),
+                    bytes::complete::tag(extension_sig.as_slice()),
+                ),
+                sequence::tuple((
+                    bytes::complete::tag(b"Realtech"),
+                    // version
+                    number::complete::le_u32,
+                    // patch count
+                    combinator::map(number::complete::le_u16, |c| c as usize),
+                    // everything else except suffix
+                    combinator::rest,
+                )),
+            ))(input)?;
+
+        // ignore remaining input, since patch offsets are relative to the complete input
+        let (_rem, (chip_ids, patch_lengths, patch_offsets)) = sequence::tuple((
+            // chip id
+            multi::many_m_n(patch_count, patch_count, number::complete::le_u16),
+            // patch length
+            multi::many_m_n(patch_count, patch_count, number::complete::le_u16),
+            // patch offset
+            multi::many_m_n(patch_count, patch_count, number::complete::le_u32),
+        ))(payload)?;
+
+        let patches = chip_ids
+            .into_iter()
+            .zip(patch_lengths.into_iter())
+            .zip(patch_offsets.into_iter())
+            .map(|((chip_id, patch_length), patch_offset)| {
+                combinator::map(
+                    sequence::preceded(
+                        bytes::complete::take(patch_offset),
+                        // ignore trailing 4-byte suffix
+                        sequence::terminated(
+                            // patch including svn version, but not suffix
+                            combinator::consumed(sequence::preceded(
+                                // patch before svn version or version suffix
+                                // prefix length underflow will show up as parse failure
+                                bytes::complete::take(patch_length.saturating_sub(8)),
+                                // svn version
+                                number::complete::le_u32,
+                            )),
+                            // dummy suffix, overwritten with firmware version
+                            bytes::complete::take(4_usize),
+                        ),
+                    ),
+                    |(patch_contents_before_version, svn_version): (&[u8], u32)| {
+                        let mut contents = patch_contents_before_version.to_vec();
+                        // replace what would have been the trailing dummy suffix with fw version
+                        contents.extend_from_slice(&fw_version.to_le_bytes());
+
+                        Patch {
+                            contents,
+                            svn_version,
+                            chip_id,
+                        }
+                    },
+                )(input)
+                .map(|(_rem, output)| output)
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        // look for project id from the end
+        let mut offset = payload.len();
+        let mut project_id: Option<u8> = None;
+        while offset >= 2 {
+            // Won't panic, since offset >= 2
+            let chunk = &payload[offset - 2..offset];
+            let length: usize = chunk[0].into();
+            let opcode = chunk[1];
+            offset -= 2;
+
+            if opcode == 0xFF {
+                break;
+            }
+            if length == 0 {
+                // report what nom likely would have done, if nom was good at parsing backwards
+                return Err(nom::Err::Error(error::Error::new(
+                    chunk,
+                    error::ErrorKind::Verify,
+                )));
+            }
+            if opcode == 0 && length == 1 {
+                project_id = offset
+                    .checked_sub(1)
+                    .and_then(|index| payload.get(index))
+                    .copied();
+                break;
+            }
+
+            offset -= length;
+        }
+
+        match project_id {
+            Some(project_id) => Ok(Firmware {
+                project_id,
+                version: fw_version,
+                patches,
+            }),
+            None => {
+                // we ran out of file without finding a project id
+                Err(nom::Err::Error(error::Error::new(
+                    payload,
+                    error::ErrorKind::Eof,
+                )))
+            }
+        }
+    }
+
+    /// Patch version
+    pub fn version(&self) -> u32 {
+        self.version
+    }
+
+    /// Project id
+    pub fn project_id(&self) -> u8 {
+        self.project_id
+    }
+
+    /// Patches
+    pub fn patches(&self) -> &[Patch] {
+        &self.patches
+    }
+}
+
+/// Patch in a [Firmware}
+pub struct Patch {
+    chip_id: u16,
+    contents: Vec<u8>,
+    svn_version: u32,
+}
+
+impl Patch {
+    /// Chip id
+    pub fn chip_id(&self) -> u16 {
+        self.chip_id
+    }
+    /// Contents of the patch, including the 4-byte firmware version suffix
+    pub fn contents(&self) -> &[u8] {
+        &self.contents
+    }
+    /// SVN version
+    pub fn svn_version(&self) -> u32 {
+        self.svn_version
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use anyhow::anyhow;
+    use std::{fs, io, path};
+
+    #[test]
+    fn parse_firmware_rtl8723b() -> anyhow::Result<()> {
+        let fw = Firmware::parse(&firmware_contents("rtl8723b_fw_structure.bin")?)
+            .map_err(|e| anyhow!("{:?}", e))?;
+
+        let fw_version = 0x0E2F9F73;
+        assert_eq!(fw_version, fw.version());
+        assert_eq!(0x0001, fw.project_id());
+        assert_eq!(
+            vec![(0x0001, 0x00002BBF, 22368,), (0x0002, 0x00002BBF, 22496,),],
+            patch_summaries(fw, fw_version)
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn parse_firmware_rtl8761bu() -> anyhow::Result<()> {
+        let fw = Firmware::parse(&firmware_contents("rtl8761bu_fw_structure.bin")?)
+            .map_err(|e| anyhow!("{:?}", e))?;
+
+        let fw_version = 0xDFC6D922;
+        assert_eq!(fw_version, fw.version());
+        assert_eq!(0x000E, fw.project_id());
+        assert_eq!(
+            vec![(0x0001, 0x00005060, 14048,), (0x0002, 0xD6D525A4, 30204,),],
+            patch_summaries(fw, fw_version)
+        );
+
+        Ok(())
+    }
+
+    fn firmware_contents(filename: &str) -> io::Result<Vec<u8>> {
+        fs::read(
+            path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+                .join("resources/test/firmware/realtek")
+                .join(filename),
+        )
+    }
+
+    /// Return a tuple of (chip id, svn version, contents len, contents sha256)
+    fn patch_summaries(fw: Firmware, fw_version: u32) -> Vec<(u16, u32, usize)> {
+        fw.patches()
+            .iter()
+            .map(|p| {
+                let contents = p.contents();
+                let mut dummy_contents = dummy_contents(contents.len());
+                dummy_contents.extend_from_slice(&p.svn_version().to_le_bytes());
+                dummy_contents.extend_from_slice(&fw_version.to_le_bytes());
+                assert_eq!(&dummy_contents, contents);
+                (p.chip_id(), p.svn_version(), contents.len())
+            })
+            .collect::<Vec<_>>()
+    }
+
+    fn dummy_contents(len: usize) -> Vec<u8> {
+        let mut vec = (len as u32).to_le_bytes().as_slice().repeat(len / 4 + 1);
+        assert!(vec.len() >= len);
+        // leave room for svn version and firmware version
+        vec.truncate(len - 8);
+        vec
+    }
+}
diff --git a/rust/src/internal/mod.rs b/rust/src/internal/mod.rs
new file mode 100644
index 0000000..f474c2d
--- /dev/null
+++ b/rust/src/internal/mod.rs
@@ -0,0 +1,20 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! It's not clear where to put Rust code that isn't simply a wrapper around Python. Until we have
+//! a good answer for what to do there, the idea is to put it in this (non-public) module, and
+//! `pub use` it into the relevant areas of the `wrapper` module so that it's still easy for users
+//! to discover.
+
+pub(crate) mod drivers;
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 73001e6..2bcb398 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -29,3 +29,5 @@
 pub mod wrapper;
 
 pub mod adv;
+
+pub(crate) mod internal;
diff --git a/rust/src/main.rs b/rust/src/main.rs
new file mode 100644
index 0000000..c21f4c8
--- /dev/null
+++ b/rust/src/main.rs
@@ -0,0 +1,271 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! CLI tools for Bumble
+
+#![deny(missing_docs, unsafe_code)]
+
+use bumble::wrapper::logging::{bumble_env_logging_level, py_logging_basic_config};
+use clap::Parser as _;
+use pyo3::PyResult;
+use std::{fmt, path};
+
+mod cli;
+
+#[pyo3_asyncio::tokio::main]
+async fn main() -> PyResult<()> {
+    env_logger::builder()
+        .filter_level(log::LevelFilter::Info)
+        .init();
+
+    py_logging_basic_config(bumble_env_logging_level("INFO"))?;
+
+    let cli: Cli = Cli::parse();
+
+    match cli.subcommand {
+        Subcommand::Firmware { subcommand: fw } => match fw {
+            Firmware::Realtek { subcommand: rtk } => match rtk {
+                Realtek::Download(dl) => {
+                    cli::firmware::rtk::download(dl).await?;
+                }
+                Realtek::Drop { transport } => cli::firmware::rtk::drop(&transport).await?,
+                Realtek::Info { transport, force } => {
+                    cli::firmware::rtk::info(&transport, force).await?;
+                }
+                Realtek::Load { transport, force } => {
+                    cli::firmware::rtk::load(&transport, force).await?
+                }
+                Realtek::Parse { firmware_path } => cli::firmware::rtk::parse(&firmware_path)?,
+            },
+        },
+        Subcommand::L2cap {
+            subcommand,
+            device_config,
+            transport,
+            psm,
+            l2cap_coc_max_credits,
+            l2cap_coc_mtu,
+            l2cap_coc_mps,
+        } => {
+            cli::l2cap::run(
+                subcommand,
+                device_config,
+                transport,
+                psm,
+                l2cap_coc_max_credits,
+                l2cap_coc_mtu,
+                l2cap_coc_mps,
+            )
+            .await?
+        }
+        Subcommand::Usb { subcommand } => match subcommand {
+            Usb::Probe(probe) => cli::usb::probe(probe.verbose)?,
+        },
+    }
+
+    Ok(())
+}
+
+#[derive(clap::Parser)]
+struct Cli {
+    #[clap(subcommand)]
+    subcommand: Subcommand,
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+enum Subcommand {
+    /// Manage device firmware
+    Firmware {
+        #[clap(subcommand)]
+        subcommand: Firmware,
+    },
+    /// L2cap client/server operations
+    L2cap {
+        #[command(subcommand)]
+        subcommand: L2cap,
+
+        /// Device configuration file.
+        ///
+        /// See, for instance, `examples/device1.json` in the Python project.
+        #[arg(long)]
+        device_config: path::PathBuf,
+        /// Bumble transport spec.
+        ///
+        /// <https://google.github.io/bumble/transports/index.html>
+        #[arg(long)]
+        transport: String,
+
+        /// PSM for L2CAP Connection-oriented Channel.
+        ///
+        /// Must be in the range [0, 65535].
+        #[arg(long)]
+        psm: u16,
+
+        /// Maximum L2CAP CoC Credits. When not specified, lets Bumble set the default.
+        ///
+        /// Must be in the range [1, 65535].
+        #[arg(long, value_parser = clap::value_parser!(u16).range(1..))]
+        l2cap_coc_max_credits: Option<u16>,
+
+        /// L2CAP CoC MTU. When not specified, lets Bumble set the default.
+        ///
+        /// Must be in the range [23, 65535].
+        #[arg(long, value_parser = clap::value_parser!(u16).range(23..))]
+        l2cap_coc_mtu: Option<u16>,
+
+        /// L2CAP CoC MPS. When not specified, lets Bumble set the default.
+        ///
+        /// Must be in the range [23, 65535].
+        #[arg(long, value_parser = clap::value_parser!(u16).range(23..))]
+        l2cap_coc_mps: Option<u16>,
+    },
+    /// USB operations
+    Usb {
+        #[clap(subcommand)]
+        subcommand: Usb,
+    },
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+enum Firmware {
+    /// Manage Realtek chipset firmware
+    Realtek {
+        #[clap(subcommand)]
+        subcommand: Realtek,
+    },
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+
+enum Realtek {
+    /// Download Realtek firmware
+    Download(Download),
+    /// Drop firmware from a USB device
+    Drop {
+        /// Bumble transport spec. Must be for a USB device.
+        ///
+        /// <https://google.github.io/bumble/transports/index.html>
+        #[arg(long)]
+        transport: String,
+    },
+    /// Show driver info for a USB device
+    Info {
+        /// Bumble transport spec. Must be for a USB device.
+        ///
+        /// <https://google.github.io/bumble/transports/index.html>
+        #[arg(long)]
+        transport: String,
+        /// Try to resolve driver info even if USB info is not available, or if the USB
+        /// (vendor,product) tuple is not in the list of known compatible RTK USB dongles.
+        #[arg(long, default_value_t = false)]
+        force: bool,
+    },
+    /// Load firmware onto a USB device
+    Load {
+        /// Bumble transport spec. Must be for a USB device.
+        ///
+        /// <https://google.github.io/bumble/transports/index.html>
+        #[arg(long)]
+        transport: String,
+        /// Load firmware even if the USB info doesn't match.
+        #[arg(long, default_value_t = false)]
+        force: bool,
+    },
+    /// Parse a firmware file
+    Parse {
+        /// Firmware file to parse
+        firmware_path: path::PathBuf,
+    },
+}
+
+#[derive(clap::Args, Debug, Clone)]
+struct Download {
+    /// Directory to download to. Defaults to an OS-specific path specific to the Bumble tool.
+    #[arg(long)]
+    output_dir: Option<path::PathBuf>,
+    /// Source to download from
+    #[arg(long, default_value_t = Source::LinuxKernel)]
+    source: Source,
+    /// Only download a single image
+    #[arg(long, value_name = "base name")]
+    single: Option<String>,
+    /// Overwrite existing files
+    #[arg(long, default_value_t = false)]
+    overwrite: bool,
+    /// Don't print the parse results for the downloaded file names
+    #[arg(long)]
+    no_parse: bool,
+}
+
+#[derive(Debug, Clone, clap::ValueEnum)]
+enum Source {
+    LinuxKernel,
+    RealtekOpensource,
+    LinuxFromScratch,
+}
+
+impl fmt::Display for Source {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Source::LinuxKernel => write!(f, "linux-kernel"),
+            Source::RealtekOpensource => write!(f, "realtek-opensource"),
+            Source::LinuxFromScratch => write!(f, "linux-from-scratch"),
+        }
+    }
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+enum L2cap {
+    /// Starts an L2CAP server
+    Server {
+        /// TCP host that the l2cap server will connect to.
+        /// Data is bridged like so:
+        ///     TCP server <-> (TCP client / **L2CAP server**) <-> (L2CAP client / TCP server) <-> TCP client
+        #[arg(long, default_value = "localhost")]
+        tcp_host: String,
+        /// TCP port that the server will connect to.
+        ///
+        /// Must be in the range [1, 65535].
+        #[arg(long, default_value_t = 9544)]
+        tcp_port: u16,
+    },
+    /// Starts an L2CAP client
+    Client {
+        /// L2cap server address that this l2cap client will connect to.
+        bluetooth_address: String,
+        /// TCP host that the l2cap client will bind to and listen for incoming TCP connections.
+        /// Data is bridged like so:
+        ///     TCP client <-> (TCP server / **L2CAP client**) <-> (L2CAP server / TCP client) <-> TCP server
+        #[arg(long, default_value = "localhost")]
+        tcp_host: String,
+        /// TCP port that the client will connect to.
+        ///
+        /// Must be in the range [1, 65535].
+        #[arg(long, default_value_t = 9543)]
+        tcp_port: u16,
+    },
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+enum Usb {
+    /// Probe the USB bus for Bluetooth devices
+    Probe(Probe),
+}
+
+#[derive(clap::Args, Debug, Clone)]
+struct Probe {
+    /// Show additional info for each USB device
+    #[arg(long, default_value_t = false)]
+    verbose: bool,
+}
diff --git a/rust/src/wrapper/device.rs b/rust/src/wrapper/device.rs
index d635754..be5e4fa 100644
--- a/rust/src/wrapper/device.rs
+++ b/rust/src/wrapper/device.rs
@@ -19,13 +19,19 @@ use crate::{
     wrapper::{
         core::AdvertisingData,
         gatt_client::{ProfileServiceProxy, ServiceProxy},
-        hci::Address,
+        hci::{Address, HciErrorCode},
+        host::Host,
+        l2cap::LeConnectionOrientedChannel,
         transport::{Sink, Source},
-        ClosureCallback,
+        ClosureCallback, PyDictExt, PyObjectExt,
     },
 };
-use pyo3::types::PyDict;
-use pyo3::{intern, types::PyModule, PyObject, PyResult, Python, ToPyObject};
+use pyo3::{
+    intern,
+    types::{PyDict, PyModule},
+    IntoPy, PyObject, PyResult, Python, ToPyObject,
+};
+use pyo3_asyncio::tokio::into_future;
 use std::path;
 
 /// A device that can send/receive HCI frames.
@@ -65,7 +71,7 @@ impl Device {
         Python::with_gil(|py| {
             self.0
                 .call_method0(py, intern!(py, "power_on"))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .map(|_| ())
@@ -76,12 +82,28 @@ impl Device {
         Python::with_gil(|py| {
             self.0
                 .call_method1(py, intern!(py, "connect"), (peer_addr,))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .map(Connection)
     }
 
+    /// Register a callback to be called for each incoming connection.
+    pub fn on_connection(
+        &mut self,
+        callback: impl Fn(Python, Connection) -> PyResult<()> + Send + 'static,
+    ) -> PyResult<()> {
+        let boxed = ClosureCallback::new(move |py, args, _kwargs| {
+            callback(py, Connection(args.get_item(0)?.into()))
+        });
+
+        Python::with_gil(|py| {
+            self.0
+                .call_method1(py, intern!(py, "add_listener"), ("connection", boxed))
+        })
+        .map(|_| ())
+    }
+
     /// Start scanning
     pub async fn start_scanning(&self, filter_duplicates: bool) -> PyResult<()> {
         Python::with_gil(|py| {
@@ -89,7 +111,7 @@ impl Device {
             kwargs.set_item("filter_duplicates", filter_duplicates)?;
             self.0
                 .call_method(py, intern!(py, "start_scanning"), (), Some(kwargs))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .map(|_| ())
@@ -123,6 +145,15 @@ impl Device {
         .map(|_| ())
     }
 
+    /// Returns the host used by the device, if any
+    pub fn host(&mut self) -> PyResult<Option<Host>> {
+        Python::with_gil(|py| {
+            self.0
+                .getattr(py, intern!(py, "host"))
+                .map(|obj| obj.into_option(Host::from))
+        })
+    }
+
     /// Start advertising the data set with [Device.set_advertisement].
     pub async fn start_advertising(&mut self, auto_restart: bool) -> PyResult<()> {
         Python::with_gil(|py| {
@@ -131,7 +162,7 @@ impl Device {
 
             self.0
                 .call_method(py, intern!(py, "start_advertising"), (), Some(kwargs))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .map(|_| ())
@@ -142,16 +173,114 @@ impl Device {
         Python::with_gil(|py| {
             self.0
                 .call_method0(py, intern!(py, "stop_advertising"))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .map(|_| ())
     }
+
+    /// Registers an L2CAP connection oriented channel server. When a client connects to the server,
+    /// the `server` callback is passed a handle to the established channel. When optional arguments
+    /// are not specified, the Python module specifies the defaults.
+    pub fn register_l2cap_channel_server(
+        &mut self,
+        psm: u16,
+        server: impl Fn(Python, LeConnectionOrientedChannel) -> PyResult<()> + Send + 'static,
+        max_credits: Option<u16>,
+        mtu: Option<u16>,
+        mps: Option<u16>,
+    ) -> PyResult<()> {
+        Python::with_gil(|py| {
+            let boxed = ClosureCallback::new(move |py, args, _kwargs| {
+                server(
+                    py,
+                    LeConnectionOrientedChannel::from(args.get_item(0)?.into()),
+                )
+            });
+
+            let kwargs = PyDict::new(py);
+            kwargs.set_item("psm", psm)?;
+            kwargs.set_item("server", boxed.into_py(py))?;
+            kwargs.set_opt_item("max_credits", max_credits)?;
+            kwargs.set_opt_item("mtu", mtu)?;
+            kwargs.set_opt_item("mps", mps)?;
+            self.0.call_method(
+                py,
+                intern!(py, "register_l2cap_channel_server"),
+                (),
+                Some(kwargs),
+            )
+        })?;
+        Ok(())
+    }
 }
 
 /// A connection to a remote device.
 pub struct Connection(PyObject);
 
+impl Connection {
+    /// Open an L2CAP channel using this connection. When optional arguments are not specified, the
+    /// Python module specifies the defaults.
+    pub async fn open_l2cap_channel(
+        &mut self,
+        psm: u16,
+        max_credits: Option<u16>,
+        mtu: Option<u16>,
+        mps: Option<u16>,
+    ) -> PyResult<LeConnectionOrientedChannel> {
+        Python::with_gil(|py| {
+            let kwargs = PyDict::new(py);
+            kwargs.set_item("psm", psm)?;
+            kwargs.set_opt_item("max_credits", max_credits)?;
+            kwargs.set_opt_item("mtu", mtu)?;
+            kwargs.set_opt_item("mps", mps)?;
+            self.0
+                .call_method(py, intern!(py, "open_l2cap_channel"), (), Some(kwargs))
+                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(LeConnectionOrientedChannel::from)
+    }
+
+    /// Disconnect from device with provided reason. When optional arguments are not specified, the
+    /// Python module specifies the defaults.
+    pub async fn disconnect(&mut self, reason: Option<HciErrorCode>) -> PyResult<()> {
+        Python::with_gil(|py| {
+            let kwargs = PyDict::new(py);
+            kwargs.set_opt_item("reason", reason)?;
+            self.0
+                .call_method(py, intern!(py, "disconnect"), (), Some(kwargs))
+                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(|_| ())
+    }
+
+    /// Register a callback to be called on disconnection.
+    pub fn on_disconnection(
+        &mut self,
+        callback: impl Fn(Python, HciErrorCode) -> PyResult<()> + Send + 'static,
+    ) -> PyResult<()> {
+        let boxed = ClosureCallback::new(move |py, args, _kwargs| {
+            callback(py, args.get_item(0)?.extract()?)
+        });
+
+        Python::with_gil(|py| {
+            self.0
+                .call_method1(py, intern!(py, "add_listener"), ("disconnection", boxed))
+        })
+        .map(|_| ())
+    }
+
+    /// Returns some information about the connection as a [String].
+    pub fn debug_string(&self) -> PyResult<String> {
+        Python::with_gil(|py| {
+            let str_obj = self.0.call_method0(py, intern!(py, "__str__"))?;
+            str_obj.gil_ref(py).extract()
+        })
+    }
+}
+
 /// The other end of a connection
 pub struct Peer(PyObject);
 
@@ -173,7 +302,7 @@ impl Peer {
         Python::with_gil(|py| {
             self.0
                 .call_method0(py, intern!(py, "discover_services"))
-                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
         })?
         .await
         .and_then(|list| {
@@ -207,13 +336,7 @@ impl Peer {
             let class = module.getattr(P::PROXY_CLASS_NAME)?;
             self.0
                 .call_method1(py, intern!(py, "create_service_proxy"), (class,))
-                .map(|obj| {
-                    if obj.is_none(py) {
-                        None
-                    } else {
-                        Some(P::wrap(obj))
-                    }
-                })
+                .map(|obj| obj.into_option(P::wrap))
         })
     }
 }
diff --git a/rust/src/wrapper/drivers/mod.rs b/rust/src/wrapper/drivers/mod.rs
new file mode 100644
index 0000000..ff38ac1
--- /dev/null
+++ b/rust/src/wrapper/drivers/mod.rs
@@ -0,0 +1,17 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Device drivers
+
+pub mod rtk;
diff --git a/rust/src/wrapper/drivers/rtk.rs b/rust/src/wrapper/drivers/rtk.rs
new file mode 100644
index 0000000..1f629d1
--- /dev/null
+++ b/rust/src/wrapper/drivers/rtk.rs
@@ -0,0 +1,141 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Drivers for Realtek controllers
+
+use crate::wrapper::{host::Host, PyObjectExt};
+use pyo3::{intern, types::PyModule, PyObject, PyResult, Python, ToPyObject};
+use pyo3_asyncio::tokio::into_future;
+
+pub use crate::internal::drivers::rtk::{Firmware, Patch};
+
+/// Driver for a Realtek controller
+pub struct Driver(PyObject);
+
+impl Driver {
+    /// Locate the driver for the provided host.
+    pub async fn for_host(host: &Host, force: bool) -> PyResult<Option<Self>> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.drivers.rtk"))?
+                .getattr(intern!(py, "Driver"))?
+                .call_method1(intern!(py, "for_host"), (&host.obj, force))
+                .and_then(into_future)
+        })?
+        .await
+        .map(|obj| obj.into_option(Self))
+    }
+
+    /// Check if the host has a known driver.
+    pub async fn check(host: &Host) -> PyResult<bool> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.drivers.rtk"))?
+                .getattr(intern!(py, "Driver"))?
+                .call_method1(intern!(py, "check"), (&host.obj,))
+                .and_then(|obj| obj.extract::<bool>())
+        })
+    }
+
+    /// Find the [DriverInfo] for the host, if one matches
+    pub async fn driver_info_for_host(host: &Host) -> PyResult<Option<DriverInfo>> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.drivers.rtk"))?
+                .getattr(intern!(py, "Driver"))?
+                .call_method1(intern!(py, "driver_info_for_host"), (&host.obj,))
+                .and_then(into_future)
+        })?
+        .await
+        .map(|obj| obj.into_option(DriverInfo))
+    }
+
+    /// Send a command to the device to drop firmware
+    pub async fn drop_firmware(host: &mut Host) -> PyResult<()> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.drivers.rtk"))?
+                .getattr(intern!(py, "Driver"))?
+                .call_method1(intern!(py, "drop_firmware"), (&host.obj,))
+                .and_then(into_future)
+        })?
+        .await
+        .map(|_| ())
+    }
+
+    /// Load firmware onto the device.
+    pub async fn download_firmware(&mut self) -> PyResult<()> {
+        Python::with_gil(|py| {
+            self.0
+                .call_method0(py, intern!(py, "download_firmware"))
+                .and_then(|coroutine| into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(|_| ())
+    }
+}
+
+/// Metadata about a known driver & applicable device
+pub struct DriverInfo(PyObject);
+
+impl DriverInfo {
+    /// Returns a list of all drivers that Bumble knows how to handle.
+    pub fn all_drivers() -> PyResult<Vec<DriverInfo>> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.drivers.rtk"))?
+                .getattr(intern!(py, "Driver"))?
+                .getattr(intern!(py, "DRIVER_INFOS"))?
+                .iter()?
+                .map(|r| r.map(|h| DriverInfo(h.to_object(py))))
+                .collect::<PyResult<Vec<_>>>()
+        })
+    }
+
+    /// The firmware file name to load from the filesystem, e.g. `foo_fw.bin`.
+    pub fn firmware_name(&self) -> PyResult<String> {
+        Python::with_gil(|py| {
+            self.0
+                .getattr(py, intern!(py, "fw_name"))?
+                .as_ref(py)
+                .extract::<String>()
+        })
+    }
+
+    /// The config file name, if any, to load from the filesystem, e.g. `foo_config.bin`.
+    pub fn config_name(&self) -> PyResult<Option<String>> {
+        Python::with_gil(|py| {
+            let obj = self.0.getattr(py, intern!(py, "config_name"))?;
+            let handle = obj.as_ref(py);
+
+            if handle.is_none() {
+                Ok(None)
+            } else {
+                handle
+                    .extract::<String>()
+                    .map(|s| if s.is_empty() { None } else { Some(s) })
+            }
+        })
+    }
+
+    /// Whether or not config is required.
+    pub fn config_needed(&self) -> PyResult<bool> {
+        Python::with_gil(|py| {
+            self.0
+                .getattr(py, intern!(py, "config_needed"))?
+                .as_ref(py)
+                .extract::<bool>()
+        })
+    }
+
+    /// ROM id
+    pub fn rom(&self) -> PyResult<u32> {
+        Python::with_gil(|py| self.0.getattr(py, intern!(py, "rom"))?.as_ref(py).extract())
+    }
+}
diff --git a/rust/src/wrapper/hci.rs b/rust/src/wrapper/hci.rs
index 48f7dc1..41dcbf3 100644
--- a/rust/src/wrapper/hci.rs
+++ b/rust/src/wrapper/hci.rs
@@ -15,7 +15,40 @@
 //! HCI
 
 use itertools::Itertools as _;
-use pyo3::{exceptions::PyException, intern, types::PyModule, PyErr, PyObject, PyResult, Python};
+use pyo3::{
+    exceptions::PyException, intern, types::PyModule, FromPyObject, PyAny, PyErr, PyObject,
+    PyResult, Python, ToPyObject,
+};
+
+/// HCI error code.
+pub struct HciErrorCode(u8);
+
+impl<'source> FromPyObject<'source> for HciErrorCode {
+    fn extract(ob: &'source PyAny) -> PyResult<Self> {
+        Ok(HciErrorCode(ob.extract()?))
+    }
+}
+
+impl ToPyObject for HciErrorCode {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
+        self.0.to_object(py)
+    }
+}
+
+/// Provides helpers for interacting with HCI
+pub struct HciConstant;
+
+impl HciConstant {
+    /// Human-readable error name
+    pub fn error_name(status: HciErrorCode) -> PyResult<String> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.hci"))?
+                .getattr(intern!(py, "HCI_Constant"))?
+                .call_method1(intern!(py, "error_name"), (status.0,))?
+                .extract()
+        })
+    }
+}
 
 /// A Bluetooth address
 pub struct Address(pub(crate) PyObject);
diff --git a/rust/src/wrapper/host.rs b/rust/src/wrapper/host.rs
new file mode 100644
index 0000000..ab81450
--- /dev/null
+++ b/rust/src/wrapper/host.rs
@@ -0,0 +1,71 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Host-side types
+
+use crate::wrapper::transport::{Sink, Source};
+use pyo3::{intern, prelude::PyModule, types::PyDict, PyObject, PyResult, Python};
+
+/// Host HCI commands
+pub struct Host {
+    pub(crate) obj: PyObject,
+}
+
+impl Host {
+    /// Create a Host that wraps the provided obj
+    pub(crate) fn from(obj: PyObject) -> Self {
+        Self { obj }
+    }
+
+    /// Create a new Host
+    pub fn new(source: Source, sink: Sink) -> PyResult<Self> {
+        Python::with_gil(|py| {
+            PyModule::import(py, intern!(py, "bumble.host"))?
+                .getattr(intern!(py, "Host"))?
+                .call((source.0, sink.0), None)
+                .map(|any| Self { obj: any.into() })
+        })
+    }
+
+    /// Send a reset command and perform other reset tasks.
+    pub async fn reset(&mut self, driver_factory: DriverFactory) -> PyResult<()> {
+        Python::with_gil(|py| {
+            let kwargs = match driver_factory {
+                DriverFactory::None => {
+                    let kw = PyDict::new(py);
+                    kw.set_item("driver_factory", py.None())?;
+                    Some(kw)
+                }
+                DriverFactory::Auto => {
+                    // leave the default in place
+                    None
+                }
+            };
+            self.obj
+                .call_method(py, intern!(py, "reset"), (), kwargs)
+                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(|_| ())
+    }
+}
+
+/// Driver factory to use when initializing a host
+#[derive(Debug, Clone)]
+pub enum DriverFactory {
+    /// Do not load drivers
+    None,
+    /// Load appropriate driver, if any is found
+    Auto,
+}
diff --git a/rust/src/wrapper/l2cap.rs b/rust/src/wrapper/l2cap.rs
new file mode 100644
index 0000000..5e0752e
--- /dev/null
+++ b/rust/src/wrapper/l2cap.rs
@@ -0,0 +1,92 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! L2CAP
+
+use crate::wrapper::{ClosureCallback, PyObjectExt};
+use pyo3::{intern, PyObject, PyResult, Python};
+
+/// L2CAP connection-oriented channel
+pub struct LeConnectionOrientedChannel(PyObject);
+
+impl LeConnectionOrientedChannel {
+    /// Create a LeConnectionOrientedChannel that wraps the provided obj.
+    pub(crate) fn from(obj: PyObject) -> Self {
+        Self(obj)
+    }
+
+    /// Queues data to be automatically sent across this channel.
+    pub fn write(&mut self, data: &[u8]) -> PyResult<()> {
+        Python::with_gil(|py| self.0.call_method1(py, intern!(py, "write"), (data,))).map(|_| ())
+    }
+
+    /// Wait for queued data to be sent on this channel.
+    pub async fn drain(&mut self) -> PyResult<()> {
+        Python::with_gil(|py| {
+            self.0
+                .call_method0(py, intern!(py, "drain"))
+                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(|_| ())
+    }
+
+    /// Register a callback to be called when the channel is closed.
+    pub fn on_close(
+        &mut self,
+        callback: impl Fn(Python) -> PyResult<()> + Send + 'static,
+    ) -> PyResult<()> {
+        let boxed = ClosureCallback::new(move |py, _args, _kwargs| callback(py));
+
+        Python::with_gil(|py| {
+            self.0
+                .call_method1(py, intern!(py, "add_listener"), ("close", boxed))
+        })
+        .map(|_| ())
+    }
+
+    /// Register a callback to be called when the channel receives data.
+    pub fn set_sink(
+        &mut self,
+        callback: impl Fn(Python, &[u8]) -> PyResult<()> + Send + 'static,
+    ) -> PyResult<()> {
+        let boxed = ClosureCallback::new(move |py, args, _kwargs| {
+            callback(py, args.get_item(0)?.extract()?)
+        });
+        Python::with_gil(|py| self.0.setattr(py, intern!(py, "sink"), boxed)).map(|_| ())
+    }
+
+    /// Disconnect the l2cap channel.
+    /// Must be called from a thread with a Python event loop, which should be true on
+    /// `tokio::main` and `async_std::main`.
+    ///
+    /// For more info, see https://awestlake87.github.io/pyo3-asyncio/master/doc/pyo3_asyncio/#event-loop-references-and-contextvars.
+    pub async fn disconnect(&mut self) -> PyResult<()> {
+        Python::with_gil(|py| {
+            self.0
+                .call_method0(py, intern!(py, "disconnect"))
+                .and_then(|coroutine| pyo3_asyncio::tokio::into_future(coroutine.as_ref(py)))
+        })?
+        .await
+        .map(|_| ())
+    }
+
+    /// Returns some information about the channel as a [String].
+    pub fn debug_string(&self) -> PyResult<String> {
+        Python::with_gil(|py| {
+            let str_obj = self.0.call_method0(py, intern!(py, "__str__"))?;
+            str_obj.gil_ref(py).extract()
+        })
+    }
+}
diff --git a/rust/src/wrapper/logging.rs b/rust/src/wrapper/logging.rs
index 141cc04..bd932cb 100644
--- a/rust/src/wrapper/logging.rs
+++ b/rust/src/wrapper/logging.rs
@@ -1,3 +1,17 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 //! Bumble & Python logging
 
 use pyo3::types::PyDict;
diff --git a/rust/src/wrapper/mod.rs b/rust/src/wrapper/mod.rs
index 2ab71c3..94ac15a 100644
--- a/rust/src/wrapper/mod.rs
+++ b/rust/src/wrapper/mod.rs
@@ -31,14 +31,17 @@ pub use pyo3_asyncio;
 pub mod assigned_numbers;
 pub mod core;
 pub mod device;
+pub mod drivers;
 pub mod gatt_client;
 pub mod hci;
+pub mod host;
+pub mod l2cap;
 pub mod logging;
 pub mod profile;
 pub mod transport;
 
 /// Convenience extensions to [PyObject]
-pub trait PyObjectExt {
+pub trait PyObjectExt: Sized {
     /// Get a GIL-bound reference
     fn gil_ref<'py>(&'py self, py: Python<'py>) -> &'py PyAny;
 
@@ -49,6 +52,17 @@ pub trait PyObjectExt {
     {
         Python::with_gil(|py| self.gil_ref(py).extract::<T>())
     }
+
+    /// If the Python object is a Python `None`, return a Rust `None`, otherwise `Some` with the mapped type
+    fn into_option<T>(self, map_obj: impl Fn(Self) -> T) -> Option<T> {
+        Python::with_gil(|py| {
+            if self.gil_ref(py).is_none() {
+                None
+            } else {
+                Some(map_obj(self))
+            }
+        })
+    }
 }
 
 impl PyObjectExt for PyObject {
@@ -57,6 +71,21 @@ impl PyObjectExt for PyObject {
     }
 }
 
+/// Convenience extensions to [PyDict]
+pub trait PyDictExt {
+    /// Set item in dict only if value is Some, otherwise do nothing.
+    fn set_opt_item<K: ToPyObject, V: ToPyObject>(&self, key: K, value: Option<V>) -> PyResult<()>;
+}
+
+impl PyDictExt for PyDict {
+    fn set_opt_item<K: ToPyObject, V: ToPyObject>(&self, key: K, value: Option<V>) -> PyResult<()> {
+        if let Some(value) = value {
+            self.set_item(key, value)?
+        }
+        Ok(())
+    }
+}
+
 /// Wrapper to make Rust closures ([Fn] implementations) callable from Python.
 ///
 /// The Python callable form returns a Python `None`.
diff --git a/rust/src/wrapper/profile.rs b/rust/src/wrapper/profile.rs
index 854ba80..fc473ff 100644
--- a/rust/src/wrapper/profile.rs
+++ b/rust/src/wrapper/profile.rs
@@ -14,7 +14,10 @@
 
 //! GATT profiles
 
-use crate::wrapper::gatt_client::{CharacteristicProxy, ProfileServiceProxy};
+use crate::wrapper::{
+    gatt_client::{CharacteristicProxy, ProfileServiceProxy},
+    PyObjectExt,
+};
 use pyo3::{intern, PyObject, PyResult, Python};
 
 /// Exposes the battery GATT service
@@ -26,13 +29,7 @@ impl BatteryServiceProxy {
         Python::with_gil(|py| {
             self.0
                 .getattr(py, intern!(py, "battery_level"))
-                .map(|level| {
-                    if level.is_none(py) {
-                        None
-                    } else {
-                        Some(CharacteristicProxy(level))
-                    }
-                })
+                .map(|level| level.into_option(CharacteristicProxy))
         })
     }
 }
diff --git a/rust/tools/file_header.rs b/rust/tools/file_header.rs
new file mode 100644
index 0000000..fb3286d
--- /dev/null
+++ b/rust/tools/file_header.rs
@@ -0,0 +1,78 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use anyhow::anyhow;
+use clap::Parser as _;
+use file_header::{
+    add_headers_recursively, check_headers_recursively,
+    license::spdx::{YearCopyrightOwnerValue, APACHE_2_0},
+};
+use globset::{Glob, GlobSet, GlobSetBuilder};
+use std::{env, path::PathBuf};
+
+fn main() -> anyhow::Result<()> {
+    let rust_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR")?);
+    let ignore_globset = ignore_globset()?;
+    // Note: when adding headers, there is a bug where the line spacing is off for Apache 2.0 (see https://github.com/spdx/license-list-XML/issues/2127)
+    let header = APACHE_2_0.build_header(YearCopyrightOwnerValue::new(2023, "Google LLC".into()));
+
+    let cli = Cli::parse();
+
+    match cli.subcommand {
+        Subcommand::CheckAll => {
+            let result =
+                check_headers_recursively(&rust_dir, |p| !ignore_globset.is_match(p), header, 4)?;
+            if result.has_failure() {
+                return Err(anyhow!(
+                    "The following files do not have headers: {result:?}"
+                ));
+            }
+        }
+        Subcommand::AddAll => {
+            let files_with_new_header =
+                add_headers_recursively(&rust_dir, |p| !ignore_globset.is_match(p), header)?;
+            files_with_new_header
+                .iter()
+                .for_each(|path| println!("Added header to: {path:?}"));
+        }
+    }
+    Ok(())
+}
+
+fn ignore_globset() -> anyhow::Result<GlobSet> {
+    Ok(GlobSetBuilder::new()
+        .add(Glob::new("**/.idea/**")?)
+        .add(Glob::new("**/target/**")?)
+        .add(Glob::new("**/.gitignore")?)
+        .add(Glob::new("**/CHANGELOG.md")?)
+        .add(Glob::new("**/Cargo.lock")?)
+        .add(Glob::new("**/Cargo.toml")?)
+        .add(Glob::new("**/README.md")?)
+        .add(Glob::new("*.bin")?)
+        .build()?)
+}
+
+#[derive(clap::Parser)]
+struct Cli {
+    #[clap(subcommand)]
+    subcommand: Subcommand,
+}
+
+#[derive(clap::Subcommand, Debug, Clone)]
+enum Subcommand {
+    /// Checks if a license is present in files that are not in the ignore list.
+    CheckAll,
+    /// Adds a license as needed to files that are not in the ignore list.
+    AddAll,
+}
diff --git a/setup.cfg b/setup.cfg
index a7a09d6..1ca73c7 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -32,17 +32,22 @@ package_dir =
 include_package_data = True
 install_requires =
     aiohttp ~= 3.8; platform_system!='Emscripten'
-    appdirs >= 1.4
-    bt-test-interfaces >= 0.0.2
+    appdirs >= 1.4; platform_system!='Emscripten'
+    bt-test-interfaces >= 0.0.2; platform_system!='Emscripten'
     click == 8.1.3; platform_system!='Emscripten'
-    cryptography == 35; platform_system!='Emscripten'
-    grpcio == 1.51.1; platform_system!='Emscripten'
-    humanize >= 4.6.0
+    cryptography == 39; platform_system!='Emscripten'
+    # Pyodide bundles a version of cryptography that is built for wasm, which may not match the
+    # versions available on PyPI. Relax the version requirement since it's better than being
+    # completely unable to import the package in case of version mismatch.
+    cryptography >= 39.0; platform_system=='Emscripten'
+    grpcio == 1.57.0; platform_system!='Emscripten'
+    humanize >= 4.6.0; platform_system!='Emscripten'
     libusb1 >= 2.0.1; platform_system!='Emscripten'
     libusb-package == 1.0.26.1; platform_system!='Emscripten'
+    platformdirs == 3.10.0; platform_system!='Emscripten'
     prompt_toolkit >= 3.0.16; platform_system!='Emscripten'
-    prettytable >= 3.6.0
-    protobuf >= 3.12.4
+    prettytable >= 3.6.0; platform_system!='Emscripten'
+    protobuf >= 3.12.4; platform_system!='Emscripten'
     pyee >= 8.2.2
     pyserial-asyncio >= 0.5; platform_system!='Emscripten'
     pyserial >= 3.5; platform_system!='Emscripten'
@@ -81,9 +86,9 @@ test =
     coverage >= 6.4
 development =
     black == 22.10
-    grpcio-tools >= 1.51.1
+    grpcio-tools >= 1.57.0
     invoke >= 1.7.3
-    mypy == 1.2.0
+    mypy == 1.5.0
     nox >= 2022
     pylint == 2.15.8
     types-appdirs >= 1.4.3
diff --git a/speaker.html b/speaker.html
deleted file mode 100644
index 05cc31f..0000000
--- a/speaker.html
+++ /dev/null
@@ -1,28 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <title>Audio WAV Player</title>
-  </head>
-  <body>
-    <h1>Audio WAV Player</h1>
-    <audio id="audioPlayer" controls>
-      <source src="" type="audio/wav">
-    </audio>
-
-    <script>
-      const audioPlayer = document.getElementById('audioPlayer');
-      const ws = new WebSocket('ws://localhost:8080');
-
-      let mediaSource = new MediaSource();
-      audioPlayer.src = URL.createObjectURL(mediaSource);
-
-      mediaSource.addEventListener('sourceopen', function(event) {
-        const sourceBuffer = mediaSource.addSourceBuffer('audio/wav');
-
-        ws.onmessage = function(event) {
-          sourceBuffer.appendBuffer(event.data);
-        };
-      });
-    </script>
-  </body>
-</html>
diff --git a/tasks.py b/tasks.py
index 3a3a01a..6df5a8b 100644
--- a/tasks.py
+++ b/tasks.py
@@ -177,3 +177,33 @@ project_tasks.add_task(lint)
 project_tasks.add_task(format_code, name="format")
 project_tasks.add_task(check_types, name="check-types")
 project_tasks.add_task(pre_commit)
+
+
+# -----------------------------------------------------------------------------
+# Web
+# -----------------------------------------------------------------------------
+web_tasks = Collection()
+ns.add_collection(web_tasks, name="web")
+
+
+# -----------------------------------------------------------------------------
+@task
+def serve(ctx, port=8000):
+    """
+    Run a simple HTTP server for the examples under the `web` directory.
+    """
+    import http.server
+
+    address = ("", port)
+
+    class Handler(http.server.SimpleHTTPRequestHandler):
+        def __init__(self, *args, **kwargs):
+            super().__init__(*args, directory="web", **kwargs)
+
+    server = http.server.HTTPServer(address, Handler)
+    print(f"Now serving on port {port} 🕸️")
+    server.serve_forever()
+
+
+# -----------------------------------------------------------------------------
+web_tasks.add_task(serve)
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..1e45f74
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
diff --git a/tests/gatt_test.py b/tests/gatt_test.py
index dd0277e..d9f6d60 100644
--- a/tests/gatt_test.py
+++ b/tests/gatt_test.py
@@ -891,10 +891,10 @@ async def async_main():
 
 
 # -----------------------------------------------------------------------------
-def test_attribute_string_to_permissions():
-    assert Attribute.string_to_permissions('READABLE') == 1
-    assert Attribute.string_to_permissions('WRITEABLE') == 2
-    assert Attribute.string_to_permissions('READABLE,WRITEABLE') == 3
+def test_permissions_from_string():
+    assert Attribute.Permissions.from_string('READABLE') == 1
+    assert Attribute.Permissions.from_string('WRITEABLE') == 2
+    assert Attribute.Permissions.from_string('READABLE,WRITEABLE') == 3
 
 
 # -----------------------------------------------------------------------------
diff --git a/tests/hfp_test.py b/tests/hfp_test.py
new file mode 100644
index 0000000..481d0b7
--- /dev/null
+++ b/tests/hfp_test.py
@@ -0,0 +1,100 @@
+# Copyright 2021-2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+import asyncio
+import logging
+import os
+import pytest
+
+from typing import Tuple
+
+from .test_utils import TwoDevices
+from bumble import hfp
+from bumble import rfcomm
+
+
+# -----------------------------------------------------------------------------
+# Logging
+# -----------------------------------------------------------------------------
+logger = logging.getLogger(__name__)
+
+
+# -----------------------------------------------------------------------------
+async def make_hfp_connections(
+    hf_config: hfp.Configuration,
+) -> Tuple[hfp.HfProtocol, hfp.HfpProtocol]:
+    # Setup devices
+    devices = TwoDevices()
+    await devices.setup_connection()
+
+    # Setup RFCOMM channel
+    wait_dlc = asyncio.get_running_loop().create_future()
+    rfcomm_channel = rfcomm.Server(devices.devices[0]).listen(
+        lambda dlc: wait_dlc.set_result(dlc)
+    )
+    assert devices.connections[0]
+    assert devices.connections[1]
+    client_mux = await rfcomm.Client(devices.devices[1], devices.connections[1]).start()
+
+    client_dlc = await client_mux.open_dlc(rfcomm_channel)
+    server_dlc = await wait_dlc
+
+    # Setup HFP connection
+    hf = hfp.HfProtocol(client_dlc, hf_config)
+    ag = hfp.HfpProtocol(server_dlc)
+    return hf, ag
+
+
+# -----------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_slc():
+    hf_config = hfp.Configuration(
+        supported_hf_features=[], supported_hf_indicators=[], supported_audio_codecs=[]
+    )
+    hf, ag = await make_hfp_connections(hf_config)
+
+    async def ag_loop():
+        while line := await ag.next_line():
+            if line.startswith('AT+BRSF'):
+                ag.send_response_line('+BRSF: 0')
+            elif line.startswith('AT+CIND=?'):
+                ag.send_response_line(
+                    '+CIND: ("call",(0,1)),("callsetup",(0-3)),("service",(0-1)),'
+                    '("signal",(0-5)),("roam",(0,1)),("battchg",(0-5)),'
+                    '("callheld",(0-2))'
+                )
+            elif line.startswith('AT+CIND?'):
+                ag.send_response_line('+CIND: 0,0,1,4,1,5,0')
+            ag.send_response_line('OK')
+
+    ag_task = asyncio.create_task(ag_loop())
+
+    await hf.initiate_slc()
+    ag_task.cancel()
+
+
+# -----------------------------------------------------------------------------
+async def run():
+    await test_slc()
+
+
+# -----------------------------------------------------------------------------
+if __name__ == '__main__':
+    logging.basicConfig(level=os.environ.get('BUMBLE_LOGLEVEL', 'INFO').upper())
+    asyncio.run(run())
diff --git a/tests/keystore_test.py b/tests/keystore_test.py
index 2e73039..2a3d48d 100644
--- a/tests/keystore_test.py
+++ b/tests/keystore_test.py
@@ -18,6 +18,8 @@
 import asyncio
 import json
 import logging
+import pathlib
+import pytest
 import tempfile
 import os
 
@@ -83,87 +85,95 @@ JSON3 = """
 
 
 # -----------------------------------------------------------------------------
-async def test_basic():
-    with tempfile.NamedTemporaryFile(mode="r+", encoding='utf-8') as file:
-        keystore = JsonKeyStore('my_namespace', file.name)
+@pytest.fixture
+def temporary_file():
+    file = tempfile.NamedTemporaryFile(delete=False)
+    file.close()
+    yield file.name
+    pathlib.Path(file.name).unlink()
+
+
+# -----------------------------------------------------------------------------
+async def test_basic(temporary_file):
+    with open(temporary_file, mode='w', encoding='utf-8') as file:
         file.write("{}")
         file.flush()
 
-        keys = await keystore.get_all()
-        assert len(keys) == 0
-
-        keys = PairingKeys()
-        await keystore.update('foo', keys)
-        foo = await keystore.get('foo')
-        assert foo is not None
-        assert foo.ltk is None
-        ltk = bytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
-        keys.ltk = PairingKeys.Key(ltk)
-        await keystore.update('foo', keys)
-        foo = await keystore.get('foo')
-        assert foo is not None
-        assert foo.ltk is not None
-        assert foo.ltk.value == ltk
+    keystore = JsonKeyStore('my_namespace', temporary_file)
 
-        file.flush()
-        with open(file.name, "r", encoding="utf-8") as json_file:
-            json_data = json.load(json_file)
-            assert 'my_namespace' in json_data
-            assert 'foo' in json_data['my_namespace']
-            assert 'ltk' in json_data['my_namespace']['foo']
+    keys = await keystore.get_all()
+    assert len(keys) == 0
+
+    keys = PairingKeys()
+    await keystore.update('foo', keys)
+    foo = await keystore.get('foo')
+    assert foo is not None
+    assert foo.ltk is None
+    ltk = bytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
+    keys.ltk = PairingKeys.Key(ltk)
+    await keystore.update('foo', keys)
+    foo = await keystore.get('foo')
+    assert foo is not None
+    assert foo.ltk is not None
+    assert foo.ltk.value == ltk
+
+    with open(file.name, "r", encoding="utf-8") as json_file:
+        json_data = json.load(json_file)
+        assert 'my_namespace' in json_data
+        assert 'foo' in json_data['my_namespace']
+        assert 'ltk' in json_data['my_namespace']['foo']
 
 
 # -----------------------------------------------------------------------------
-async def test_parsing():
-    with tempfile.NamedTemporaryFile(mode="w", encoding='utf-8') as file:
-        keystore = JsonKeyStore('my_namespace', file.name)
+async def test_parsing(temporary_file):
+    with open(temporary_file, mode='w', encoding='utf-8') as file:
         file.write(JSON1)
         file.flush()
 
-        foo = await keystore.get('14:7D:DA:4E:53:A8/P')
-        assert foo is not None
-        assert foo.ltk.value == bytes.fromhex('d1897ee10016eb1a08e4e037fd54c683')
+    keystore = JsonKeyStore('my_namespace', file.name)
+    foo = await keystore.get('14:7D:DA:4E:53:A8/P')
+    assert foo is not None
+    assert foo.ltk.value == bytes.fromhex('d1897ee10016eb1a08e4e037fd54c683')
 
 
 # -----------------------------------------------------------------------------
-async def test_default_namespace():
-    with tempfile.NamedTemporaryFile(mode="w", encoding='utf-8') as file:
-        keystore = JsonKeyStore(None, file.name)
+async def test_default_namespace(temporary_file):
+    with open(temporary_file, mode='w', encoding='utf-8') as file:
         file.write(JSON1)
         file.flush()
 
-        all_keys = await keystore.get_all()
-        assert len(all_keys) == 1
-        name, keys = all_keys[0]
-        assert name == '14:7D:DA:4E:53:A8/P'
-        assert keys.irk.value == bytes.fromhex('e7b2543b206e4e46b44f9e51dad22bd1')
+    keystore = JsonKeyStore(None, file.name)
+    all_keys = await keystore.get_all()
+    assert len(all_keys) == 1
+    name, keys = all_keys[0]
+    assert name == '14:7D:DA:4E:53:A8/P'
+    assert keys.irk.value == bytes.fromhex('e7b2543b206e4e46b44f9e51dad22bd1')
 
-    with tempfile.NamedTemporaryFile(mode="w", encoding='utf-8') as file:
-        keystore = JsonKeyStore(None, file.name)
+    with open(temporary_file, mode='w', encoding='utf-8') as file:
         file.write(JSON2)
         file.flush()
 
-        keys = PairingKeys()
-        ltk = bytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
-        keys.ltk = PairingKeys.Key(ltk)
-        await keystore.update('foo', keys)
-        file.flush()
-        with open(file.name, "r", encoding="utf-8") as json_file:
-            json_data = json.load(json_file)
-            assert '__DEFAULT__' in json_data
-            assert 'foo' in json_data['__DEFAULT__']
-            assert 'ltk' in json_data['__DEFAULT__']['foo']
-
-    with tempfile.NamedTemporaryFile(mode="w", encoding='utf-8') as file:
-        keystore = JsonKeyStore(None, file.name)
+    keystore = JsonKeyStore(None, file.name)
+    keys = PairingKeys()
+    ltk = bytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
+    keys.ltk = PairingKeys.Key(ltk)
+    await keystore.update('foo', keys)
+    with open(file.name, "r", encoding="utf-8") as json_file:
+        json_data = json.load(json_file)
+        assert '__DEFAULT__' in json_data
+        assert 'foo' in json_data['__DEFAULT__']
+        assert 'ltk' in json_data['__DEFAULT__']['foo']
+
+    with open(temporary_file, mode='w', encoding='utf-8') as file:
         file.write(JSON3)
         file.flush()
 
-        all_keys = await keystore.get_all()
-        assert len(all_keys) == 1
-        name, keys = all_keys[0]
-        assert name == '14:7D:DA:4E:53:A8/P'
-        assert keys.irk.value == bytes.fromhex('e7b2543b206e4e46b44f9e51dad22bd1')
+    keystore = JsonKeyStore(None, file.name)
+    all_keys = await keystore.get_all()
+    assert len(all_keys) == 1
+    name, keys = all_keys[0]
+    assert name == '14:7D:DA:4E:53:A8/P'
+    assert keys.irk.value == bytes.fromhex('e7b2543b206e4e46b44f9e51dad22bd1')
 
 
 # -----------------------------------------------------------------------------
diff --git a/tests/l2cap_test.py b/tests/l2cap_test.py
index 6f8e181..c6b2340 100644
--- a/tests/l2cap_test.py
+++ b/tests/l2cap_test.py
@@ -21,13 +21,9 @@ import os
 import random
 import pytest
 
-from bumble.controller import Controller
-from bumble.link import LocalLink
-from bumble.device import Device
-from bumble.host import Host
-from bumble.transport import AsyncPipeSink
 from bumble.core import ProtocolError
 from bumble.l2cap import L2CAP_Connection_Request
+from .test_utils import TwoDevices
 
 
 # -----------------------------------------------------------------------------
@@ -37,60 +33,6 @@ logger = logging.getLogger(__name__)
 
 
 # -----------------------------------------------------------------------------
-class TwoDevices:
-    def __init__(self):
-        self.connections = [None, None]
-
-        self.link = LocalLink()
-        self.controllers = [
-            Controller('C1', link=self.link),
-            Controller('C2', link=self.link),
-        ]
-        self.devices = [
-            Device(
-                address='F0:F1:F2:F3:F4:F5',
-                host=Host(self.controllers[0], AsyncPipeSink(self.controllers[0])),
-            ),
-            Device(
-                address='F5:F4:F3:F2:F1:F0',
-                host=Host(self.controllers[1], AsyncPipeSink(self.controllers[1])),
-            ),
-        ]
-
-        self.paired = [None, None]
-
-    def on_connection(self, which, connection):
-        self.connections[which] = connection
-
-    def on_paired(self, which, keys):
-        self.paired[which] = keys
-
-
-# -----------------------------------------------------------------------------
-async def setup_connection():
-    # Create two devices, each with a controller, attached to the same link
-    two_devices = TwoDevices()
-
-    # Attach listeners
-    two_devices.devices[0].on(
-        'connection', lambda connection: two_devices.on_connection(0, connection)
-    )
-    two_devices.devices[1].on(
-        'connection', lambda connection: two_devices.on_connection(1, connection)
-    )
-
-    # Start
-    await two_devices.devices[0].power_on()
-    await two_devices.devices[1].power_on()
-
-    # Connect the two devices
-    await two_devices.devices[0].connect(two_devices.devices[1].random_address)
-
-    # Check the post conditions
-    assert two_devices.connections[0] is not None
-    assert two_devices.connections[1] is not None
-
-    return two_devices
 
 
 # -----------------------------------------------------------------------------
@@ -132,7 +74,8 @@ def test_helpers():
 # -----------------------------------------------------------------------------
 @pytest.mark.asyncio
 async def test_basic_connection():
-    devices = await setup_connection()
+    devices = TwoDevices()
+    await devices.setup_connection()
     psm = 1234
 
     # Check that if there's no one listening, we can't connect
@@ -184,7 +127,8 @@ async def test_basic_connection():
 
 # -----------------------------------------------------------------------------
 async def transfer_payload(max_credits, mtu, mps):
-    devices = await setup_connection()
+    devices = TwoDevices()
+    await devices.setup_connection()
 
     received = []
 
@@ -226,7 +170,8 @@ async def test_transfer():
 # -----------------------------------------------------------------------------
 @pytest.mark.asyncio
 async def test_bidirectional_transfer():
-    devices = await setup_connection()
+    devices = TwoDevices()
+    await devices.setup_connection()
 
     client_received = []
     server_received = []
diff --git a/tests/sdp_test.py b/tests/sdp_test.py
index f07b579..090e7b2 100644
--- a/tests/sdp_test.py
+++ b/tests/sdp_test.py
@@ -15,15 +15,30 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
-from bumble.core import UUID
-from bumble.sdp import DataElement
+import asyncio
+import logging
+import os
+
+from bumble.core import UUID, BT_L2CAP_PROTOCOL_ID, BT_RFCOMM_PROTOCOL_ID
+from bumble.sdp import (
+    DataElement,
+    ServiceAttribute,
+    Client,
+    Server,
+    SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
+    SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
+    SDP_PUBLIC_BROWSE_ROOT,
+    SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
+    SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
+)
+from .test_utils import TwoDevices
 
 # -----------------------------------------------------------------------------
 # pylint: disable=invalid-name
 # -----------------------------------------------------------------------------
 
 # -----------------------------------------------------------------------------
-def basic_check(x):
+def basic_check(x: DataElement) -> None:
     serialized = bytes(x)
     if len(serialized) < 500:
         print('Original:', x)
@@ -41,7 +56,7 @@ def basic_check(x):
 
 
 # -----------------------------------------------------------------------------
-def test_data_elements():
+def test_data_elements() -> None:
     e = DataElement(DataElement.NIL, None)
     basic_check(e)
 
@@ -157,5 +172,108 @@ def test_data_elements():
 
 
 # -----------------------------------------------------------------------------
-if __name__ == '__main__':
+def sdp_records():
+    return {
+        0x00010001: [
+            ServiceAttribute(
+                SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
+                DataElement.unsigned_integer_32(0x00010001),
+            ),
+            ServiceAttribute(
+                SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
+                DataElement.sequence([DataElement.uuid(SDP_PUBLIC_BROWSE_ROOT)]),
+            ),
+            ServiceAttribute(
+                SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
+                DataElement.sequence(
+                    [DataElement.uuid(UUID('E6D55659-C8B4-4B85-96BB-B1143AF6D3AE'))]
+                ),
+            ),
+            ServiceAttribute(
+                SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
+                DataElement.sequence(
+                    [
+                        DataElement.sequence([DataElement.uuid(BT_L2CAP_PROTOCOL_ID)]),
+                    ]
+                ),
+            ),
+        ]
+    }
+
+
+# -----------------------------------------------------------------------------
+async def test_service_search():
+    # Setup connections
+    devices = TwoDevices()
+    await devices.setup_connection()
+    assert devices.connections[0]
+    assert devices.connections[1]
+
+    # Register SDP service
+    devices.devices[0].sdp_server.service_records.update(sdp_records())
+
+    # Search for service
+    client = Client(devices.devices[1])
+    await client.connect(devices.connections[1])
+    services = await client.search_services(
+        [UUID('E6D55659-C8B4-4B85-96BB-B1143AF6D3AE')]
+    )
+
+    # Then
+    assert services[0] == 0x00010001
+
+
+# -----------------------------------------------------------------------------
+async def test_service_attribute():
+    # Setup connections
+    devices = TwoDevices()
+    await devices.setup_connection()
+
+    # Register SDP service
+    devices.devices[0].sdp_server.service_records.update(sdp_records())
+
+    # Search for service
+    client = Client(devices.devices[1])
+    await client.connect(devices.connections[1])
+    attributes = await client.get_attributes(
+        0x00010001, [SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID]
+    )
+
+    # Then
+    assert attributes[0].value.value == sdp_records()[0x00010001][0].value.value
+
+
+# -----------------------------------------------------------------------------
+async def test_service_search_attribute():
+    # Setup connections
+    devices = TwoDevices()
+    await devices.setup_connection()
+
+    # Register SDP service
+    devices.devices[0].sdp_server.service_records.update(sdp_records())
+
+    # Search for service
+    client = Client(devices.devices[1])
+    await client.connect(devices.connections[1])
+    attributes = await client.search_attributes(
+        [UUID('E6D55659-C8B4-4B85-96BB-B1143AF6D3AE')], [(0x0000FFFF, 8)]
+    )
+
+    # Then
+    for expect, actual in zip(attributes, sdp_records().values()):
+        assert expect.id == actual.id
+        assert expect.value == actual.value
+
+
+# -----------------------------------------------------------------------------
+async def run():
     test_data_elements()
+    await test_service_attribute()
+    await test_service_search()
+    await test_service_search_attribute()
+
+
+# -----------------------------------------------------------------------------
+if __name__ == '__main__':
+    logging.basicConfig(level=os.environ.get('BUMBLE_LOGLEVEL', 'INFO').upper())
+    asyncio.run(run())
diff --git a/tests/test_utils.py b/tests/test_utils.py
new file mode 100644
index 0000000..f19f18c
--- /dev/null
+++ b/tests/test_utils.py
@@ -0,0 +1,73 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import List, Optional
+
+from bumble.controller import Controller
+from bumble.link import LocalLink
+from bumble.device import Device, Connection
+from bumble.host import Host
+from bumble.transport import AsyncPipeSink
+from bumble.hci import Address
+
+
+class TwoDevices:
+    connections: List[Optional[Connection]]
+
+    def __init__(self) -> None:
+        self.connections = [None, None]
+
+        self.link = LocalLink()
+        self.controllers = [
+            Controller('C1', link=self.link),
+            Controller('C2', link=self.link),
+        ]
+        self.devices = [
+            Device(
+                address=Address('F0:F1:F2:F3:F4:F5'),
+                host=Host(self.controllers[0], AsyncPipeSink(self.controllers[0])),
+            ),
+            Device(
+                address=Address('F5:F4:F3:F2:F1:F0'),
+                host=Host(self.controllers[1], AsyncPipeSink(self.controllers[1])),
+            ),
+        ]
+
+        self.paired = [None, None]
+
+    def on_connection(self, which, connection):
+        self.connections[which] = connection
+
+    def on_paired(self, which, keys):
+        self.paired[which] = keys
+
+    async def setup_connection(self) -> None:
+        # Attach listeners
+        self.devices[0].on(
+            'connection', lambda connection: self.on_connection(0, connection)
+        )
+        self.devices[1].on(
+            'connection', lambda connection: self.on_connection(1, connection)
+        )
+
+        # Start
+        await self.devices[0].power_on()
+        await self.devices[1].power_on()
+
+        # Connect the two devices
+        await self.devices[0].connect(self.devices[1].random_address)
+
+        # Check the post conditions
+        assert self.connections[0] is not None
+        assert self.connections[1] is not None
diff --git a/tests/utils_test.py b/tests/utils_test.py
new file mode 100644
index 0000000..d6f5780
--- /dev/null
+++ b/tests/utils_test.py
@@ -0,0 +1,77 @@
+# Copyright 2021-2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import contextlib
+import logging
+import os
+
+from bumble import utils
+from pyee import EventEmitter
+from unittest.mock import MagicMock
+
+
+def test_on() -> None:
+    emitter = EventEmitter()
+    with contextlib.closing(utils.EventWatcher()) as context:
+        mock = MagicMock()
+        context.on(emitter, 'event', mock)
+
+        emitter.emit('event')
+
+    assert not emitter.listeners('event')
+    assert mock.call_count == 1
+
+
+def test_on_decorator() -> None:
+    emitter = EventEmitter()
+    with contextlib.closing(utils.EventWatcher()) as context:
+        mock = MagicMock()
+
+        @context.on(emitter, 'event')
+        def on_event(*_) -> None:
+            mock()
+
+        emitter.emit('event')
+
+    assert not emitter.listeners('event')
+    assert mock.call_count == 1
+
+
+def test_multiple_handlers() -> None:
+    emitter = EventEmitter()
+    with contextlib.closing(utils.EventWatcher()) as context:
+        mock = MagicMock()
+
+        context.once(emitter, 'a', mock)
+        context.once(emitter, 'b', mock)
+
+        emitter.emit('b', 'b')
+
+    assert not emitter.listeners('a')
+    assert not emitter.listeners('b')
+
+    mock.assert_called_once_with('b')
+
+
+# -----------------------------------------------------------------------------
+def run_tests():
+    test_on()
+    test_on_decorator()
+    test_multiple_handlers()
+
+
+# -----------------------------------------------------------------------------
+if __name__ == '__main__':
+    logging.basicConfig(level=os.environ.get('BUMBLE_LOGLEVEL', 'INFO').upper())
+    run_tests()
diff --git a/tools/rtk_fw_download.py b/tools/rtk_fw_download.py
index b027141..89c49b2 100644
--- a/tools/rtk_fw_download.py
+++ b/tools/rtk_fw_download.py
@@ -67,8 +67,9 @@ def download_file(base_url, name, remove_suffix):
 @click.command
 @click.option(
     "--output-dir",
-    default=".",
-    help="Output directory where the files will be saved",
+    default="",
+    help="Output directory where the files will be saved. Defaults to the OS-specific"
+    "app data dir, which the driver will check when trying to find firmware",
     show_default=True,
 )
 @click.option(
@@ -84,7 +85,10 @@ def main(output_dir, source, single, force, parse):
     """Download RTK firmware images and configs."""
 
     # Check that the output dir exists
-    output_dir = pathlib.Path(output_dir)
+    if output_dir == '':
+        output_dir = rtk.rtk_firmware_dir()
+    else:
+        output_dir = pathlib.Path(output_dir)
     if not output_dir.is_dir():
         print("Output dir does not exist or is not a directory")
         return
diff --git a/tools/rtk_util.py b/tools/rtk_util.py
index 7452915..35afd92 100644
--- a/tools/rtk_util.py
+++ b/tools/rtk_util.py
@@ -61,9 +61,8 @@ async def do_load(usb_transport, force):
         # Get the driver.
         driver = await rtk.Driver.for_host(host, force)
         if driver is None:
-            if not force:
-                print("Firmware already loaded or no supported driver for this device.")
-                return
+            print("Firmware already loaded or no supported driver for this device.")
+            return
 
         await driver.download_firmware()
 
diff --git a/web/README.md b/web/README.md
new file mode 100644
index 0000000..a8cc89c
--- /dev/null
+++ b/web/README.md
@@ -0,0 +1,48 @@
+Bumble For Web Browsers
+=======================
+
+Early prototype the consists of running the Bumble stack in a web browser
+environment, using [pyodide](https://pyodide.org/)
+
+Two examples are included here:
+ 
+  * scanner - a simple scanner
+  * speaker - a pure-web-based version of the Speaker app
+
+Both examples rely on the shared code in `bumble.js`.
+
+Running The Examples
+--------------------
+
+To run the examples, you will need an HTTP server to serve the HTML and JS files, and
+and a WebSocket server serving an HCI transport.
+
+For HCI over WebSocket, recent versions of the `netsim` virtual controller support it,
+or you may use the Bumble HCI Bridge app to bridge a WebSocket server to a virtual
+controller using some other transport (ex: `python apps/hci_bridge.py ws-server:_:9999 usb:0`).
+
+For HTTP, start an HTTP server with the `web` directory as its
+root. You can use the invoke task `inv web.serve` for convenience.
+
+In a browser, open either `scanner/scanner.html` or `speaker/speaker.html`.
+You can pass optional query parameters:
+
+  * `package` may be set to point to a local build of Bumble (`.whl` files).
+     The filename must be URL-encoded of course, and must be located under
+     the `web` directory (the HTTP server won't serve files not under its
+     root directory).
+  * `hci` may be set to specify a non-default WebSocket URL to use as the HCI
+     transport (the default is: `"ws://localhost:9922/hci`). This also needs
+     to be URL-encoded.
+
+Example:
+    With a local HTTP server running on port 8000, to run the `scanner` example
+    with a locally-built Bumble package `../bumble-0.0.163.dev5+g6f832b6.d20230812-py3-none-any.whl` 
+    (assuming that `bumble-0.0.163.dev5+g6f832b6.d20230812-py3-none-any.whl` exists under the `web`
+    directory and the HCI WebSocket transport at `ws://localhost:9999/hci`, the URL with the 
+    URL-encoded query parameters would be:
+    `http://localhost:8000/scanner/scanner.html?hci=ws%3A%2F%2Flocalhost%3A9999%2Fhci&package=..%2Fbumble-0.0.163.dev5%2Bg6f832b6.d20230812-py3-none-any.whl`
+
+
+NOTE: to get a local build of the Bumble package, use `inv build`, the built `.whl` file can be found in the `dist` directory. 
+Make a copy of the built `.whl` file in the `web` directory.
\ No newline at end of file
diff --git a/web/bumble.js b/web/bumble.js
new file mode 100644
index 0000000..b1243a5
--- /dev/null
+++ b/web/bumble.js
@@ -0,0 +1,91 @@
+function bufferToHex(buffer) {
+    return [...new Uint8Array(buffer)].map(x => x.toString(16).padStart(2, '0')).join('');
+}
+
+class PacketSource {
+    constructor(pyodide) {
+        this.parser = pyodide.runPython(`
+        from bumble.transport.common import PacketParser
+        class ProxiedPacketParser(PacketParser):
+            def feed_data(self, js_data):
+                super().feed_data(bytes(js_data.to_py()))
+        ProxiedPacketParser()
+      `);
+    }
+
+    set_packet_sink(sink) {
+        this.parser.set_packet_sink(sink);
+    }
+
+    data_received(data) {
+        console.log(`HCI[controller->host]: ${bufferToHex(data)}`);
+        this.parser.feed_data(data);
+    }
+}
+
+class PacketSink {
+    constructor(writer) {
+        this.writer = writer;
+    }
+
+    on_packet(packet) {
+        const buffer = packet.toJs({create_proxies : false});
+        packet.destroy();
+        console.log(`HCI[host->controller]: ${bufferToHex(buffer)}`);
+        // TODO: create an async queue here instead of blindly calling write without awaiting
+        this.writer(buffer);
+    }
+}
+
+export async function connectWebSocketTransport(pyodide, hciWsUrl) {
+    return new Promise((resolve, reject) => {
+        let resolved = false;
+
+        let ws = new WebSocket(hciWsUrl);
+        ws.binaryType = "arraybuffer";
+
+        ws.onopen = () => {
+            console.log("WebSocket open");
+            resolve({
+                packet_source,
+                packet_sink
+            });
+            resolved = true;
+        }
+
+        ws.onclose = () => {
+            console.log("WebSocket close");
+            if (!resolved) {
+                reject(`Failed to connect to ${hciWsUrl}`)
+            }
+        }
+
+        ws.onmessage = (event) => {
+            packet_source.data_received(event.data);
+        }
+
+        const packet_source = new PacketSource(pyodide);
+        const packet_sink = new PacketSink((packet) => ws.send(packet));
+    })
+}
+
+export async function loadBumble(pyodide, bumblePackage) {
+    // Load the Bumble module
+    await pyodide.loadPackage("micropip");
+    await pyodide.runPythonAsync(`
+        import micropip
+        await micropip.install("${bumblePackage}")
+        package_list = micropip.list()
+        print(package_list)
+    `)
+
+    // Mount a filesystem so that we can persist data like the Key Store
+    let mountDir = "/bumble";
+    pyodide.FS.mkdir(mountDir);
+    pyodide.FS.mount(pyodide.FS.filesystems.IDBFS, { root: "." }, mountDir);
+
+    // Sync previously persisted filesystem data into memory
+    pyodide.FS.syncfs(true, () => {
+        console.log("FS synced in")
+    });
+}
\ No newline at end of file
diff --git a/web/index.html b/web/index.html
deleted file mode 100644
index 4374db0..0000000
--- a/web/index.html
+++ /dev/null
@@ -1,131 +0,0 @@
-<html>
-  <head>
-    <script src="https://cdn.jsdelivr.net/pyodide/v0.19.1/full/pyodide.js"></script>
-  </head>
-
-  <body>
-    <button onclick="runUSB()">USB</button>
-    <button onclick="runSerial()">Serial</button>
-    <br />
-    <br />
-    <div>Output:</div>
-    <textarea id="output" style="width: 100%;" rows="30" disabled></textarea>
-
-    <script>
-        function bufferToHex(buffer) {
-            return [...new Uint8Array(buffer)].map(x => x.toString(16).padStart(2, '0')).join('');
-        }
-
-        const output = document.getElementById("output");
-        const code = document.getElementById("code");
-
-        function addToOutput(s) {
-            output.value += s + "\n";
-        }
-
-      output.value = "Initializing...\n";
-
-      async function main() {
-          let pyodide = await loadPyodide({
-              indexURL: "https://cdn.jsdelivr.net/pyodide/v0.19.1/full/",
-          })
-          output.value += "Ready!\n"
-
-          return pyodide;
-      }
-
-      let pyodideReadyPromise = main();
-
-      async function readLoop(port, packet_source) {
-        const reader = port.readable.getReader()
-            try {
-                while (true) {
-                    console.log('@@@ Reading...')
-                    const { done, value } = await reader.read()
-                    if (done) {
-                        console.log("--- DONE!")
-                        break
-                    }
-
-                    console.log('@@@ Serial data:', bufferToHex(value))
-                    if (packet_source.delegate !== undefined) {
-                        packet_source.delegate.data_received(value)
-                    } else {
-                        console.warn('@@@ delegate not set yet, dropping data')
-                    }
-                }
-            } catch (error) {
-                console.error(error)
-            } finally {
-                reader.releaseLock()
-            }
-      }
-
-      async function runUSB() {
-        const device = await navigator.usb.requestDevice({
-          filters: [
-            {
-                classCode: 0xE0,
-                subclassCode: 0x01
-            }
-          ]
-        });
-
-        if (device.configuration === null) {
-          await device.selectConfiguration(1);
-        }
-        await device.claimInterface(0)
-      }
-
-      async function runSerial() {
-        const ports = await navigator.serial.getPorts()
-          console.log('Paired ports:', ports)
-
-          const port = await navigator.serial.requestPort()
-          await port.open({ baudRate: 1000000 })
-          const writer = port.writable.getWriter()
-      }
-
-      async function run() {
-
-          let pyodide = await pyodideReadyPromise;
-          try {
-              const script = await(await fetch('scanner.py')).text()
-              await pyodide.loadPackage('micropip')
-              await pyodide.runPythonAsync(`
-                  import micropip
-                  await micropip.install('../dist/bumble-0.0.36.dev0+g3adbfe7.d20210807-py3-none-any.whl')
-              `)
-              let output = await pyodide.runPythonAsync(script)
-              addToOutput(output)
-
-              const pythonMain = pyodide.globals.get('main')
-              const packet_source = {}
-              const packet_sink = {
-                  on_packet: (packet) => {
-                    // Variant A, with the conversion done in Javascript
-                      const buffer = packet.toJs()
-                      console.log(`$$$ on_packet: ${bufferToHex(buffer)}`)
-                      // TODO: create an sync queue here instead of blindly calling write without awaiting
-                      /*await*/ writer.write(buffer)
-                      packet.destroy()
-
-                    // Variant B, with the conversion `to_js` done at the Python layer
-                    // console.log(`$$$ on_packet: ${bufferToHex(packet)}`)
-                    //   /*await*/ writer.write(packet)
-                }
-              }
-              serialLooper = readLoop(port, packet_source)
-              pythonResult = await pythonMain(packet_source, packet_sink)
-              console.log(pythonResult)
-              serialResult = await serialLooper
-              writer.releaseLock()
-              await port.close()
-              console.log('### done')
-        } catch (err) {
-          addToOutput(err);
-        }
-      }
-    </script>
-  </body>
-</html>
diff --git a/web/scanner/scanner.html b/web/scanner/scanner.html
new file mode 100644
index 0000000..12c65dd
--- /dev/null
+++ b/web/scanner/scanner.html
@@ -0,0 +1,129 @@
+<html>
+
+<head>
+  <script src="https://cdn.jsdelivr.net/pyodide/v0.23.2/full/pyodide.js"></script>
+  <style>
+    body {
+      font-family: monospace;
+    }
+
+    table, th, td {
+      padding: 2px;
+      white-space: pre;
+      border: 1px solid black;
+      border-collapse: collapse;
+    }
+  </style>
+</head>
+
+<body>
+  <button id="connectButton" disabled>Connect</button>
+  <br />
+  <br />
+  <div>Log Output</div><br>
+  <textarea id="output" style="width: 100%;" rows="10" disabled></textarea>
+  <div id="scanTableContainer"><table></table></div>
+
+  <script type="module">
+    import { loadBumble, connectWebSocketTransport } from "../bumble.js"
+    let pyodide;
+    let output;
+
+    function logToOutput(s) {
+      output.value += s + "\n";
+      console.log(s);
+    }
+
+    async function run() {
+      const params = (new URL(document.location)).searchParams;
+      const hciWsUrl = params.get("hci") || "ws://localhost:9922/hci";
+
+      try {
+        // Create a WebSocket HCI transport
+        let transport
+        try {
+          transport = await connectWebSocketTransport(pyodide, hciWsUrl);
+        } catch (error) {
+          logToOutput(error);
+          return;
+        }
+
+        // Run the scanner example
+        const script = await (await fetch("scanner.py")).text();
+        await pyodide.runPythonAsync(script);
+        const pythonMain = pyodide.globals.get("main");
+        logToOutput("Starting scanner...");
+        await pythonMain(transport.packet_source, transport.packet_sink, onScanUpdate);
+        logToOutput("Scanner running");
+      } catch (err) {
+        logToOutput(err);
+      }
+    }
+
+    function onScanUpdate(scanEntries) {
+      scanEntries = scanEntries.toJs();
+
+      const scanTable = document.createElement("table");
+
+      const tableHeader = document.createElement("tr");
+      for (const name of ["Address", "Address Type", "RSSI", "Data"]) {
+        const header = document.createElement("th");
+        header.appendChild(document.createTextNode(name));
+        tableHeader.appendChild(header);
+      }
+      scanTable.appendChild(tableHeader);
+
+      scanEntries.forEach(entry => {
+        const row = document.createElement("tr");
+
+        const addressCell = document.createElement("td");
+        addressCell.appendChild(document.createTextNode(entry.address));
+        row.appendChild(addressCell);
+
+        const addressTypeCell = document.createElement("td");
+        addressTypeCell.appendChild(document.createTextNode(entry.address_type));
+        row.appendChild(addressTypeCell);
+
+        const rssiCell = document.createElement("td");
+        rssiCell.appendChild(document.createTextNode(entry.rssi));
+        row.appendChild(rssiCell);
+
+        const dataCell = document.createElement("td");
+        dataCell.appendChild(document.createTextNode(entry.data));
+        row.appendChild(dataCell);
+
+        scanTable.appendChild(row);
+      });
+
+      const scanTableContainer = document.getElementById("scanTableContainer");
+      scanTableContainer.replaceChild(scanTable, scanTableContainer.firstChild);
+
+      return true;
+    }
+
+    async function main() {
+      output = document.getElementById("output");
+
+      // Load pyodide
+      logToOutput("Loading Pyodide");
+      pyodide = await loadPyodide();
+
+      // Load Bumble
+      logToOutput("Loading Bumble");
+      const params = (new URL(document.location)).searchParams;
+      const bumblePackage = params.get("package") || "bumble";
+      await loadBumble(pyodide, bumblePackage);
+
+      logToOutput("Ready!")
+
+      // Enable the Connect button
+      const connectButton = document.getElementById("connectButton");
+      connectButton.disabled = false
+      connectButton.addEventListener("click", run)
+    }
+
+    main();
+  </script>
+</body>
+
+</html>
\ No newline at end of file
diff --git a/web/scanner.py b/web/scanner/scanner.py
index 59eda67..c0fc456 100644
--- a/web/scanner.py
+++ b/web/scanner/scanner.py
@@ -15,50 +15,38 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+import time
+
 from bumble.device import Device
-from bumble.transport.common import PacketParser
 
 
 # -----------------------------------------------------------------------------
-class ScannerListener(Device.Listener):
-    def on_advertisement(self, advertisement):
-        address_type_string = ('P', 'R', 'PI', 'RI')[advertisement.address.address_type]
-        print(
-            f'>>> {advertisement.address} [{address_type_string}]: RSSI={advertisement.rssi}, {advertisement.ad_data}'
-        )
-
-
-class HciSource:
-    def __init__(self, host_source):
-        self.parser = PacketParser()
-        host_source.delegate = self
+class ScanEntry:
+    def __init__(self, advertisement):
+        self.address = advertisement.address.to_string(False)
+        self.address_type = ('Public', 'Random', 'Public Identity', 'Random Identity')[
+            advertisement.address.address_type
+        ]
+        self.rssi = advertisement.rssi
+        self.data = advertisement.data.to_string("\n")
 
-    def set_packet_sink(self, sink):
-        self.parser.set_packet_sink(sink)
 
-    # host source delegation
-    def data_received(self, data):
-        print('*** DATA from JS:', data)
-        buffer = bytes(data.to_py())
-        self.parser.feed_data(buffer)
-
-
-# class HciSink:
-#     def __init__(self, host_sink):
-#         self.host_sink = host_sink
+# -----------------------------------------------------------------------------
+class ScannerListener(Device.Listener):
+    def __init__(self, callback):
+        self.callback = callback
+        self.entries = {}
 
-#     def on_packet(self, packet):
-#         print(f'>>> PACKET from Python: {packet}')
-#         self.host_sink.on_packet(packet)
+    def on_advertisement(self, advertisement):
+        self.entries[advertisement.address] = ScanEntry(advertisement)
+        self.callback(list(self.entries.values()))
 
 
 # -----------------------------------------------------------------------------
-async def main(host_source, host_sink):
+async def main(hci_source, hci_sink, callback):
     print('### Starting Scanner')
-    hci_source = HciSource(host_source)
-    hci_sink = host_sink
     device = Device.with_hci('Bumble', 'F0:F1:F2:F3:F4:F5', hci_source, hci_sink)
-    device.listener = ScannerListener()
+    device.listener = ScannerListener(callback)
     await device.power_on()
     await device.start_scanning()
 
diff --git a/web/speaker/logo.svg b/web/speaker/logo.svg
new file mode 100644
index 0000000..70ef7a9
--- /dev/null
+++ b/web/speaker/logo.svg
@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!-- Created with Vectornator for iOS (http://vectornator.io/) --><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg height="100%" style="fill-rule:nonzero;clip-rule:evenodd;stroke-linecap:round;stroke-linejoin:round;" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" xml:space="preserve" width="100%" xmlns:vectornator="http://vectornator.io" version="1.1" viewBox="0 0 745 744.634">
+<metadata>
+<vectornator:setting key="DimensionsVisible" value="1"/>
+<vectornator:setting key="PencilOnly" value="0"/>
+<vectornator:setting key="SnapToPoints" value="0"/>
+<vectornator:setting key="OutlineMode" value="0"/>
+<vectornator:setting key="CMYKEnabledKey" value="0"/>
+<vectornator:setting key="RulersVisible" value="1"/>
+<vectornator:setting key="SnapToEdges" value="0"/>
+<vectornator:setting key="GuidesVisible" value="1"/>
+<vectornator:setting key="DisplayWhiteBackground" value="0"/>
+<vectornator:setting key="doHistoryDisabled" value="0"/>
+<vectornator:setting key="SnapToGuides" value="1"/>
+<vectornator:setting key="TimeLapseWatermarkDisabled" value="0"/>
+<vectornator:setting key="Units" value="Pixels"/>
+<vectornator:setting key="DynamicGuides" value="0"/>
+<vectornator:setting key="IsolateActiveLayer" value="0"/>
+<vectornator:setting key="SnapToGrid" value="0"/>
+</metadata>
+<defs/>
+<g id="Layer 1" vectornator:layerName="Layer 1">
+<path stroke="#000000" stroke-width="18.6464" d="M368.753+729.441L58.8847+550.539L58.8848+192.734L368.753+13.8313L678.621+192.734L678.621+550.539L368.753+729.441Z" fill="#0082fc" stroke-linecap="butt" fill-opacity="0.307489" opacity="1" stroke-linejoin="round"/>
+<g opacity="1">
+<g opacity="1">
+<path stroke="#000000" stroke-width="20" d="M292.873+289.256L442.872+289.256L442.872+539.254L292.873+539.254L292.873+289.256Z" fill="#fcd100" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="20" d="M292.873+289.256C292.873+247.835+326.452+214.257+367.873+214.257C409.294+214.257+442.872+247.835+442.872+289.256C442.872+330.677+409.294+364.256+367.873+364.256C326.452+364.256+292.873+330.677+292.873+289.256Z" fill="#fcd100" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="20" d="M292.873+539.254C292.873+497.833+326.452+464.255+367.873+464.255C409.294+464.255+442.872+497.833+442.872+539.254C442.872+580.675+409.294+614.254+367.873+614.254C326.452+614.254+292.873+580.675+292.873+539.254Z" fill="#fcd100" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<path stroke="#0082fc" stroke-width="0.1" d="M302.873+289.073L432.872+289.073L432.872+539.072L302.873+539.072L302.873+289.073Z" fill="#fcd100" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+</g>
+<path stroke="#000000" stroke-width="0.1" d="M103.161+309.167L226.956+443.903L366.671+309.604L103.161+309.167Z" fill="#0082fc" stroke-linecap="round" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="0.1" d="M383.411+307.076L508.887+440.112L650.5+307.507L383.411+307.076Z" fill="#0082fc" stroke-linecap="round" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="20" d="M522.045+154.808L229.559+448.882L83.8397+300.104L653.666+302.936L511.759+444.785L223.101+156.114" fill="none" stroke-linecap="round" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="61.8698" d="M295.857+418.738L438.9+418.738" fill="none" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<path stroke="#000000" stroke-width="61.8698" d="M295.857+521.737L438.9+521.737" fill="none" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<g opacity="1">
+<path stroke="#0082fc" stroke-width="0.1" d="M367.769+667.024L367.821+616.383L403.677+616.336C383.137+626.447+368.263+638.69+367.769+667.024Z" fill="#000000" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+<path stroke="#0082fc" stroke-width="0.1" d="M367.836+667.024L367.784+616.383L331.928+616.336C352.468+626.447+367.341+638.69+367.836+667.024Z" fill="#000000" stroke-linecap="butt" opacity="1" stroke-linejoin="round"/>
+</g>
+</g>
+</g>
+</svg>
diff --git a/web/speaker/speaker.css b/web/speaker/speaker.css
new file mode 100644
index 0000000..988392a
--- /dev/null
+++ b/web/speaker/speaker.css
@@ -0,0 +1,76 @@
+body, h1, h2, h3, h4, h5, h6 {
+    font-family: sans-serif;
+}
+
+#controlsDiv {
+    margin: 6px;
+}
+
+#errorText {
+    background-color: rgb(239, 89, 75);
+    border: none;
+    border-radius: 4px;
+    padding: 8px;
+    display: inline-block;
+    margin: 4px;
+}
+
+#startButton {
+    padding: 4px;
+    margin: 6px;
+}
+
+#fftCanvas {
+    border-radius: 16px;
+    margin: 6px;
+}
+
+#bandwidthCanvas {
+    border: grey;
+    border-style: solid;
+    border-radius: 8px;
+    margin: 6px;
+}
+
+#streamStateText {
+    background-color: rgb(93, 165, 93);
+    border: none;
+    border-radius: 8px;
+    padding: 10px 20px;
+    display: inline-block;
+    margin: 6px;
+}
+
+#connectionStateText {
+    background-color: rgb(112, 146, 206);
+    border: none;
+    border-radius: 8px;
+    padding: 10px 20px;
+    display: inline-block;
+    margin: 6px;
+}
+
+#propertiesTable {
+    border: grey;
+    border-style: solid;
+    border-radius: 4px;
+    padding: 4px;
+    margin: 6px;
+    margin-left: 0px;
+}
+
+th, td {
+    padding-left: 6px;
+    padding-right: 6px;
+}
+
+.properties td:nth-child(even) {
+    background-color: #D6EEEE;
+    font-family: monospace;
+}
+
+.properties td:nth-child(odd) {
+    font-weight: bold;
+}
+
+.properties tr td:nth-child(2) { width: 150px; }
\ No newline at end of file
diff --git a/web/speaker/speaker.html b/web/speaker/speaker.html
new file mode 100644
index 0000000..a20f084
--- /dev/null
+++ b/web/speaker/speaker.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Bumble Speaker</title>
+  <script src="https://cdn.jsdelivr.net/pyodide/v0.23.2/full/pyodide.js"></script>
+  <script type="module" src="speaker.js"></script>
+  <link rel="stylesheet" href="speaker.css">
+</head>
+<body>
+  <h1><img src="logo.svg" width=100 height=100 style="vertical-align:middle" alt=""/>Bumble Virtual Speaker</h1>
+  <div id="errorText"></div>
+  <div id="speaker">
+    <table><tr>
+      <td>
+        <table id="propertiesTable" class="properties">
+          <tr><td>Codec</td><td><span id="codecText"></span></td></tr>
+          <tr><td>Packets</td><td><span id="packetsReceivedText"></span></td></tr>
+          <tr><td>Bytes</td><td><span id="bytesReceivedText"></span></td></tr>
+        </table>
+      </td>
+      <td>
+        <canvas id="bandwidthCanvas" width="500", height="100">Bandwidth Graph</canvas>
+      </td>
+    </tr></table>
+    <span id="streamStateText">IDLE</span>
+    <span id="connectionStateText">NOT CONNECTED</span>
+    <div id="controlsDiv">
+        <button id="audioOnButton">Audio On</button>
+    </div>
+    <canvas id="fftCanvas" width="1024", height="300">Audio Frequencies Animation</canvas>
+    <audio id="audio"></audio>
+  </div>
+</body>
+</html>
\ No newline at end of file
diff --git a/web/speaker/speaker.js b/web/speaker/speaker.js
new file mode 100644
index 0000000..b94180f
--- /dev/null
+++ b/web/speaker/speaker.js
@@ -0,0 +1,289 @@
+import { loadBumble, connectWebSocketTransport } from "../bumble.js";
+
+(function () {
+    'use strict';
+
+    let codecText;
+    let packetsReceivedText;
+    let bytesReceivedText;
+    let streamStateText;
+    let connectionStateText;
+    let errorText;
+    let audioOnButton;
+    let mediaSource;
+    let sourceBuffer;
+    let audioElement;
+    let audioContext;
+    let audioAnalyzer;
+    let audioFrequencyBinCount;
+    let audioFrequencyData;
+    let packetsReceived = 0;
+    let bytesReceived = 0;
+    let audioState = "stopped";
+    let streamState = "IDLE";
+    let fftCanvas;
+    let fftCanvasContext;
+    let bandwidthCanvas;
+    let bandwidthCanvasContext;
+    let bandwidthBinCount;
+    let bandwidthBins = [];
+    let pyodide;
+
+    const FFT_WIDTH = 800;
+    const FFT_HEIGHT = 256;
+    const BANDWIDTH_WIDTH = 500;
+    const BANDWIDTH_HEIGHT = 100;
+
+
+    function init() {
+        initUI();
+        initMediaSource();
+        initAudioElement();
+        initAnalyzer();
+        initBumble();
+    }
+
+    function initUI() {
+        audioOnButton = document.getElementById("audioOnButton");
+        codecText = document.getElementById("codecText");
+        packetsReceivedText = document.getElementById("packetsReceivedText");
+        bytesReceivedText = document.getElementById("bytesReceivedText");
+        streamStateText = document.getElementById("streamStateText");
+        errorText = document.getElementById("errorText");
+        connectionStateText = document.getElementById("connectionStateText");
+
+        audioOnButton.onclick = () => startAudio();
+
+        codecText.innerText = "AAC";
+        setErrorText("");
+
+        requestAnimationFrame(onAnimationFrame);
+    }
+
+    function initMediaSource() {
+        mediaSource = new MediaSource();
+        mediaSource.onsourceopen = onMediaSourceOpen;
+        mediaSource.onsourceclose = onMediaSourceClose;
+        mediaSource.onsourceended = onMediaSourceEnd;
+    }
+
+    function initAudioElement() {
+        audioElement = document.getElementById("audio");
+        audioElement.src = URL.createObjectURL(mediaSource);
+        // audioElement.controls = true;
+    }
+
+    function initAnalyzer() {
+        fftCanvas = document.getElementById("fftCanvas");
+        fftCanvas.width = FFT_WIDTH
+        fftCanvas.height = FFT_HEIGHT
+        fftCanvasContext = fftCanvas.getContext('2d');
+        fftCanvasContext.fillStyle = "rgb(0, 0, 0)";
+        fftCanvasContext.fillRect(0, 0, FFT_WIDTH, FFT_HEIGHT);
+
+        bandwidthCanvas = document.getElementById("bandwidthCanvas");
+        bandwidthCanvas.width = BANDWIDTH_WIDTH
+        bandwidthCanvas.height = BANDWIDTH_HEIGHT
+        bandwidthCanvasContext = bandwidthCanvas.getContext('2d');
+        bandwidthCanvasContext.fillStyle = "rgb(255, 255, 255)";
+        bandwidthCanvasContext.fillRect(0, 0, BANDWIDTH_WIDTH, BANDWIDTH_HEIGHT);
+    }
+
+    async function initBumble() {
+        // Load pyodide
+        console.log("Loading Pyodide");
+        pyodide = await loadPyodide();
+
+        // Load Bumble
+        console.log("Loading Bumble");
+        const params = (new URL(document.location)).searchParams;
+        const bumblePackage = params.get("package") || "bumble";
+        await loadBumble(pyodide, bumblePackage);
+
+        console.log("Ready!")
+
+        const hciWsUrl = params.get("hci") || "ws://localhost:9922/hci";
+        try {
+            // Create a WebSocket HCI transport
+            let transport
+            try {
+                transport = await connectWebSocketTransport(pyodide, hciWsUrl);
+            } catch (error) {
+                console.error(error);
+                setErrorText(error);
+                return;
+            }
+
+            // Run the scanner example
+            const script = await (await fetch("speaker.py")).text();
+            await pyodide.runPythonAsync(script);
+            const pythonMain = pyodide.globals.get("main");
+            console.log("Starting speaker...");
+            await pythonMain(transport.packet_source, transport.packet_sink, onEvent);
+            console.log("Speaker running");
+        } catch (err) {
+            console.log(err);
+        }
+    }
+
+    function startAnalyzer() {
+        // FFT
+        if (audioElement.captureStream !== undefined) {
+            audioContext = new AudioContext();
+            audioAnalyzer = audioContext.createAnalyser();
+            audioAnalyzer.fftSize = 128;
+            audioFrequencyBinCount = audioAnalyzer.frequencyBinCount;
+            audioFrequencyData = new Uint8Array(audioFrequencyBinCount);
+            const stream = audioElement.captureStream();
+            const source = audioContext.createMediaStreamSource(stream);
+            source.connect(audioAnalyzer);
+        }
+
+        // Bandwidth
+        bandwidthBinCount = BANDWIDTH_WIDTH / 2;
+        bandwidthBins = [];
+    }
+
+    function setErrorText(message) {
+        errorText.innerText = message;
+        if (message.length == 0) {
+            errorText.style.display = "none";
+        } else {
+            errorText.style.display = "inline-block";
+        }
+    }
+
+    function setStreamState(state) {
+        streamState = state;
+        streamStateText.innerText = streamState;
+    }
+
+    function onAnimationFrame() {
+        // FFT
+        if (audioAnalyzer !== undefined) {
+            audioAnalyzer.getByteFrequencyData(audioFrequencyData);
+            fftCanvasContext.fillStyle = "rgb(0, 0, 0)";
+            fftCanvasContext.fillRect(0, 0, FFT_WIDTH, FFT_HEIGHT);
+            const barCount = audioFrequencyBinCount;
+            const barWidth = (FFT_WIDTH / audioFrequencyBinCount) - 1;
+            for (let bar = 0; bar < barCount; bar++) {
+                const barHeight = audioFrequencyData[bar];
+                fftCanvasContext.fillStyle = `rgb(${barHeight / 256 * 200 + 50}, 50, ${50 + 2 * bar})`;
+                fftCanvasContext.fillRect(bar * (barWidth + 1), FFT_HEIGHT - barHeight, barWidth, barHeight);
+            }
+        }
+
+        // Bandwidth
+        bandwidthCanvasContext.fillStyle = "rgb(255, 255, 255)";
+        bandwidthCanvasContext.fillRect(0, 0, BANDWIDTH_WIDTH, BANDWIDTH_HEIGHT);
+        bandwidthCanvasContext.fillStyle = `rgb(100, 100, 100)`;
+        for (let t = 0; t < bandwidthBins.length; t++) {
+            const lineHeight = (bandwidthBins[t] / 1000) * BANDWIDTH_HEIGHT;
+            bandwidthCanvasContext.fillRect(t * 2, BANDWIDTH_HEIGHT - lineHeight, 2, lineHeight);
+        }
+
+        // Display again at the next frame
+        requestAnimationFrame(onAnimationFrame);
+    }
+
+    function onMediaSourceOpen() {
+        console.log(this.readyState);
+        sourceBuffer = mediaSource.addSourceBuffer("audio/aac");
+    }
+
+    function onMediaSourceClose() {
+        console.log(this.readyState);
+    }
+
+    function onMediaSourceEnd() {
+        console.log(this.readyState);
+    }
+
+    async function startAudio() {
+        try {
+            console.log("starting audio...");
+            audioOnButton.disabled = true;
+            audioState = "starting";
+            await audioElement.play();
+            console.log("audio started");
+            audioState = "playing";
+            startAnalyzer();
+        } catch (error) {
+            console.error(`play failed: ${error}`);
+            audioState = "stopped";
+            audioOnButton.disabled = false;
+        }
+    }
+
+    async function onEvent(name, params) {
+        // Dispatch the message.
+        const handlerName = `on${name.charAt(0).toUpperCase()}${name.slice(1)}`
+        const handler = eventHandlers[handlerName];
+        if (handler !== undefined) {
+            handler(params);
+        } else {
+            console.warn(`unhandled event: ${name}`)
+        }
+    }
+
+    function onStart() {
+        setStreamState("STARTED");
+    }
+
+    function onStop() {
+        setStreamState("STOPPED");
+    }
+
+    function onSuspend() {
+        setStreamState("SUSPENDED");
+    }
+
+    function onConnection(params) {
+        connectionStateText.innerText = `CONNECTED: ${params.get('peer_name')} (${params.get('peer_address')})`;
+    }
+
+    function onDisconnection(params) {
+        connectionStateText.innerText = "DISCONNECTED";
+    }
+
+    function onAudio(python_packet) {
+        const packet = python_packet.toJs({create_proxies : false});
+        python_packet.destroy();
+        if (audioState != "stopped") {
+            // Queue the audio packet.
+            sourceBuffer.appendBuffer(packet);
+        }
+
+        packetsReceived += 1;
+        packetsReceivedText.innerText = packetsReceived;
+        bytesReceived += packet.byteLength;
+        bytesReceivedText.innerText = bytesReceived;
+
+        bandwidthBins[bandwidthBins.length] = packet.byteLength;
+        if (bandwidthBins.length > bandwidthBinCount) {
+            bandwidthBins.shift();
+        }
+    }
+
+    function onKeystoreupdate() {
+        // Sync the FS
+        pyodide.FS.syncfs(() => {
+            console.log("FS synced out")
+        });
+    }
+
+    const eventHandlers = {
+        onStart,
+        onStop,
+        onSuspend,
+        onConnection,
+        onDisconnection,
+        onAudio,
+        onKeystoreupdate
+    }
+
+    window.onload = (event) => {
+        init();
+    }
+
+}());
\ No newline at end of file
diff --git a/web/speaker/speaker.py b/web/speaker/speaker.py
new file mode 100644
index 0000000..d9293a4
--- /dev/null
+++ b/web/speaker/speaker.py
@@ -0,0 +1,321 @@
+# Copyright 2021-2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+from __future__ import annotations
+import enum
+import logging
+from typing import Dict, List
+
+from bumble.core import BT_BR_EDR_TRANSPORT, CommandTimeoutError
+from bumble.device import Device, DeviceConfiguration
+from bumble.pairing import PairingConfig
+from bumble.sdp import ServiceAttribute
+from bumble.avdtp import (
+    AVDTP_AUDIO_MEDIA_TYPE,
+    Listener,
+    MediaCodecCapabilities,
+    MediaPacket,
+    Protocol,
+)
+from bumble.a2dp import (
+    make_audio_sink_service_sdp_records,
+    MPEG_2_AAC_LC_OBJECT_TYPE,
+    A2DP_SBC_CODEC_TYPE,
+    A2DP_MPEG_2_4_AAC_CODEC_TYPE,
+    SBC_MONO_CHANNEL_MODE,
+    SBC_DUAL_CHANNEL_MODE,
+    SBC_SNR_ALLOCATION_METHOD,
+    SBC_LOUDNESS_ALLOCATION_METHOD,
+    SBC_STEREO_CHANNEL_MODE,
+    SBC_JOINT_STEREO_CHANNEL_MODE,
+    SbcMediaCodecInformation,
+    AacMediaCodecInformation,
+)
+from bumble.utils import AsyncRunner
+from bumble.codecs import AacAudioRtpPacket
+
+
+# -----------------------------------------------------------------------------
+# Logging
+# -----------------------------------------------------------------------------
+logger = logging.getLogger(__name__)
+
+
+# -----------------------------------------------------------------------------
+class AudioExtractor:
+    @staticmethod
+    def create(codec: str):
+        if codec == 'aac':
+            return AacAudioExtractor()
+        if codec == 'sbc':
+            return SbcAudioExtractor()
+
+    def extract_audio(self, packet: MediaPacket) -> bytes:
+        raise NotImplementedError()
+
+
+# -----------------------------------------------------------------------------
+class AacAudioExtractor:
+    def extract_audio(self, packet: MediaPacket) -> bytes:
+        return AacAudioRtpPacket(packet.payload).to_adts()
+
+
+# -----------------------------------------------------------------------------
+class SbcAudioExtractor:
+    def extract_audio(self, packet: MediaPacket) -> bytes:
+        # header = packet.payload[0]
+        # fragmented = header >> 7
+        # start = (header >> 6) & 0x01
+        # last = (header >> 5) & 0x01
+        # number_of_frames = header & 0x0F
+
+        # TODO: support fragmented payloads
+        return packet.payload[1:]
+
+
+# -----------------------------------------------------------------------------
+class Speaker:
+    class StreamState(enum.Enum):
+        IDLE = 0
+        STOPPED = 1
+        STARTED = 2
+        SUSPENDED = 3
+
+    def __init__(self, hci_source, hci_sink, emit_event, codec, discover):
+        self.hci_source = hci_source
+        self.hci_sink = hci_sink
+        self.emit_event = emit_event
+        self.codec = codec
+        self.discover = discover
+        self.device = None
+        self.connection = None
+        self.listener = None
+        self.packets_received = 0
+        self.bytes_received = 0
+        self.stream_state = Speaker.StreamState.IDLE
+        self.audio_extractor = AudioExtractor.create(codec)
+
+    def sdp_records(self) -> Dict[int, List[ServiceAttribute]]:
+        service_record_handle = 0x00010001
+        return {
+            service_record_handle: make_audio_sink_service_sdp_records(
+                service_record_handle
+            )
+        }
+
+    def codec_capabilities(self) -> MediaCodecCapabilities:
+        if self.codec == 'aac':
+            return self.aac_codec_capabilities()
+
+        if self.codec == 'sbc':
+            return self.sbc_codec_capabilities()
+
+        raise RuntimeError('unsupported codec')
+
+    def aac_codec_capabilities(self) -> MediaCodecCapabilities:
+        return MediaCodecCapabilities(
+            media_type=AVDTP_AUDIO_MEDIA_TYPE,
+            media_codec_type=A2DP_MPEG_2_4_AAC_CODEC_TYPE,
+            media_codec_information=AacMediaCodecInformation.from_lists(
+                object_types=[MPEG_2_AAC_LC_OBJECT_TYPE],
+                sampling_frequencies=[48000, 44100],
+                channels=[1, 2],
+                vbr=1,
+                bitrate=256000,
+            ),
+        )
+
+    def sbc_codec_capabilities(self) -> MediaCodecCapabilities:
+        return MediaCodecCapabilities(
+            media_type=AVDTP_AUDIO_MEDIA_TYPE,
+            media_codec_type=A2DP_SBC_CODEC_TYPE,
+            media_codec_information=SbcMediaCodecInformation.from_lists(
+                sampling_frequencies=[48000, 44100, 32000, 16000],
+                channel_modes=[
+                    SBC_MONO_CHANNEL_MODE,
+                    SBC_DUAL_CHANNEL_MODE,
+                    SBC_STEREO_CHANNEL_MODE,
+                    SBC_JOINT_STEREO_CHANNEL_MODE,
+                ],
+                block_lengths=[4, 8, 12, 16],
+                subbands=[4, 8],
+                allocation_methods=[
+                    SBC_LOUDNESS_ALLOCATION_METHOD,
+                    SBC_SNR_ALLOCATION_METHOD,
+                ],
+                minimum_bitpool_value=2,
+                maximum_bitpool_value=53,
+            ),
+        )
+
+    def on_key_store_update(self):
+        print("Key Store updated")
+        self.emit_event('keystoreupdate', None)
+
+    def on_bluetooth_connection(self, connection):
+        print(f'Connection: {connection}')
+        self.connection = connection
+        connection.on('disconnection', self.on_bluetooth_disconnection)
+        peer_name = '' if connection.peer_name is None else connection.peer_name
+        peer_address = connection.peer_address.to_string(False)
+        self.emit_event(
+            'connection', {'peer_name': peer_name, 'peer_address': peer_address}
+        )
+
+    def on_bluetooth_disconnection(self, reason):
+        print(f'Disconnection ({reason})')
+        self.connection = None
+        AsyncRunner.spawn(self.advertise())
+        self.emit_event('disconnection', None)
+
+    def on_avdtp_connection(self, protocol):
+        print('Audio Stream Open')
+
+        # Add a sink endpoint to the server
+        sink = protocol.add_sink(self.codec_capabilities())
+        sink.on('start', self.on_sink_start)
+        sink.on('stop', self.on_sink_stop)
+        sink.on('suspend', self.on_sink_suspend)
+        sink.on('configuration', lambda: self.on_sink_configuration(sink.configuration))
+        sink.on('rtp_packet', self.on_rtp_packet)
+        sink.on('rtp_channel_open', self.on_rtp_channel_open)
+        sink.on('rtp_channel_close', self.on_rtp_channel_close)
+
+        # Listen for close events
+        protocol.on('close', self.on_avdtp_close)
+
+        # Discover all endpoints on the remote device is requested
+        if self.discover:
+            AsyncRunner.spawn(self.discover_remote_endpoints(protocol))
+
+    def on_avdtp_close(self):
+        print("Audio Stream Closed")
+
+    def on_sink_start(self):
+        print("Sink Started")
+        self.stream_state = self.StreamState.STARTED
+        self.emit_event('start', None)
+
+    def on_sink_stop(self):
+        print("Sink Stopped")
+        self.stream_state = self.StreamState.STOPPED
+        self.emit_event('stop', None)
+
+    def on_sink_suspend(self):
+        print("Sink Suspended")
+        self.stream_state = self.StreamState.SUSPENDED
+        self.emit_event('suspend', None)
+
+    def on_sink_configuration(self, config):
+        print("Sink Configuration:")
+        print('\n'.join(["  " + str(capability) for capability in config]))
+
+    def on_rtp_channel_open(self):
+        print("RTP Channel Open")
+
+    def on_rtp_channel_close(self):
+        print("RTP Channel Closed")
+        self.stream_state = self.StreamState.IDLE
+
+    def on_rtp_packet(self, packet):
+        self.packets_received += 1
+        self.bytes_received += len(packet.payload)
+        self.emit_event("audio", self.audio_extractor.extract_audio(packet))
+
+    async def advertise(self):
+        await self.device.set_discoverable(True)
+        await self.device.set_connectable(True)
+
+    async def connect(self, address):
+        # Connect to the source
+        print(f'=== Connecting to {address}...')
+        connection = await self.device.connect(address, transport=BT_BR_EDR_TRANSPORT)
+        print(f'=== Connected to {connection.peer_address}')
+
+        # Request authentication
+        print('*** Authenticating...')
+        await connection.authenticate()
+        print('*** Authenticated')
+
+        # Enable encryption
+        print('*** Enabling encryption...')
+        await connection.encrypt()
+        print('*** Encryption on')
+
+        protocol = await Protocol.connect(connection)
+        self.listener.set_server(connection, protocol)
+        self.on_avdtp_connection(protocol)
+
+    async def discover_remote_endpoints(self, protocol):
+        endpoints = await protocol.discover_remote_endpoints()
+        print(f'@@@ Found {len(endpoints)} endpoints')
+        for endpoint in endpoints:
+            print('@@@', endpoint)
+
+    async def run(self, connect_address):
+        # Create a device
+        device_config = DeviceConfiguration()
+        device_config.name = "Bumble Speaker"
+        device_config.class_of_device = 0x240414
+        device_config.keystore = "JsonKeyStore:/bumble/keystore.json"
+        device_config.classic_enabled = True
+        device_config.le_enabled = False
+        self.device = Device.from_config_with_hci(
+            device_config, self.hci_source, self.hci_sink
+        )
+
+        # Setup the SDP to expose the sink service
+        self.device.sdp_service_records = self.sdp_records()
+
+        # Don't require MITM when pairing.
+        self.device.pairing_config_factory = lambda connection: PairingConfig(
+            mitm=False
+        )
+
+        # Start the controller
+        await self.device.power_on()
+
+        # Listen for Bluetooth connections
+        self.device.on('connection', self.on_bluetooth_connection)
+
+        # Listen for changes to the key store
+        self.device.on('key_store_update', self.on_key_store_update)
+
+        # Create a listener to wait for AVDTP connections
+        self.listener = Listener(Listener.create_registrar(self.device))
+        self.listener.on('connection', self.on_avdtp_connection)
+
+        print(f'Speaker ready to play, codec={self.codec}')
+
+        if connect_address:
+            # Connect to the source
+            try:
+                await self.connect(connect_address)
+            except CommandTimeoutError:
+                print("Connection timed out")
+                return
+        else:
+            # Start being discoverable and connectable
+            print("Waiting for connection...")
+            await self.advertise()
+
+
+# -----------------------------------------------------------------------------
+async def main(hci_source, hci_sink, emit_event):
+    # logging.basicConfig(level='DEBUG')
+    speaker = Speaker(hci_source, hci_sink, emit_event, "aac", False)
+    await speaker.run(None)