Move Connection libs outside vhal_v2_0.

The connection libs are going to be used by AIDL VHAL as well so
move them to a common place.

Bug: 215419573
Test: Presubmit
Change-Id: Ibff7030089fa4fd891bfeaee5604d9dba3ae07df

11 files changed, 984 insertions, 0 deletions

diff --git a/emulator/Conn/CommConn/Android.bp b/emulator/Conn/CommConn/Android.bp
new file mode 100644
index 0000000..9de4e08
--- /dev/null
+++ b/emulator/Conn/CommConn/Android.bp
@@ -0,0 +1,33 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// 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.
+
+package {
+    default_applicable_licenses: ["device_generic_car_license"],
+}
+
+cc_library {
+    name: "EmulatorCommConn",
+    vendor: true,
+    srcs: [
+        "*.cpp",
+    ],
+    shared_libs: [
+        "liblog",
+        "libprotobuf-cpp-lite",
+    ],
+    export_include_dirs: ["include"],
+    static_libs: [
+        "android.hardware.automotive.vehicle@2.0-libproto-native",
+    ],
+}
diff --git a/emulator/Conn/CommConn/CommConn.cpp b/emulator/Conn/CommConn/CommConn.cpp
new file mode 100644
index 0000000..800a539
--- /dev/null
+++ b/emulator/Conn/CommConn/CommConn.cpp
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "CommConn"
+
+#include <thread>
+
+#include <log/log.h>
+
+#include "CommConn.h"
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+void CommConn::start() {
+    mReadThread = std::make_unique<std::thread>(std::bind(&CommConn::readThread, this));
+}
+
+void CommConn::stop() {
+    if (mReadThread->joinable()) {
+        mReadThread->join();
+    }
+}
+
+void CommConn::sendMessage(vhal_proto::EmulatorMessage const& msg) {
+    int numBytes = msg.ByteSize();
+    std::vector<uint8_t> buffer(static_cast<size_t>(numBytes));
+    if (!msg.SerializeToArray(buffer.data(), numBytes)) {
+        ALOGE("%s: SerializeToString failed!", __func__);
+        return;
+    }
+
+    write(buffer);
+}
+
+void CommConn::readThread() {
+    std::vector<uint8_t> buffer;
+    while (isOpen()) {
+        buffer = read();
+        if (buffer.size() == 0) {
+            ALOGI("%s: Read returned empty message, exiting read loop.", __func__);
+            break;
+        }
+
+        vhal_proto::EmulatorMessage rxMsg;
+        if (rxMsg.ParseFromArray(buffer.data(), static_cast<int32_t>(buffer.size()))) {
+            vhal_proto::EmulatorMessage respMsg;
+            mMessageProcessor->processMessage(rxMsg, respMsg);
+
+            sendMessage(respMsg);
+        }
+    }
+}
+
+}  // namespace impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
diff --git a/emulator/Conn/CommConn/include/CommConn.h b/emulator/Conn/CommConn/include/CommConn.h
new file mode 100644
index 0000000..cbc8281
--- /dev/null
+++ b/emulator/Conn/CommConn/include/CommConn.h
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef ANDROID_EMULATORCOMMCONN_COMMCONN_H
+#define ANDROID_EMULATORCOMMCONN_COMMCONN_H
+
+#include <string>
+#include <thread>
+#include <vector>
+
+#include "VehicleHalProto.pb.h"
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+/**
+ * MessageProcess is an interface implemented by VehicleEmulator to process messages received
+ * over a CommConn.
+ */
+class MessageProcessor {
+   public:
+    virtual ~MessageProcessor() = default;
+
+    /**
+     * Process a single message received over a CommConn. Populate the given respMsg with the reply
+     * message we should send.
+     */
+    virtual void processMessage(vhal_proto::EmulatorMessage const& rxMsg,
+                                vhal_proto::EmulatorMessage& respMsg) = 0;
+};
+
+/**
+ * This is the interface that both PipeComm and SocketComm use to represent a connection. The
+ * connection will listen for commands on a separate 'read' thread.
+ */
+class CommConn {
+   public:
+    CommConn(MessageProcessor* messageProcessor) : mMessageProcessor(messageProcessor) {}
+
+    virtual ~CommConn() {}
+
+    /**
+     * Start the read thread reading messages from this connection.
+     */
+    virtual void start();
+
+    /**
+     * Closes a connection if it is open.
+     */
+    virtual void stop();
+
+    /**
+     * Returns true if the connection is open and available to send/receive.
+     */
+    virtual bool isOpen() = 0;
+
+    /**
+     * Blocking call to read data from the connection.
+     *
+     * @return std::vector<uint8_t> Serialized protobuf data received from emulator.  This will be
+     *              an empty vector if the connection was closed or some other error occurred.
+     */
+    virtual std::vector<uint8_t> read() = 0;
+
+    /**
+     * Transmits a string of data to the emulator.
+     *
+     * @param data Serialized protobuf data to transmit.
+     *
+     * @return int Number of bytes transmitted, or -1 if failed.
+     */
+    virtual int write(const std::vector<uint8_t>& data) = 0;
+
+    /**
+     * Serialized and send the given message to the other side.
+     */
+    void sendMessage(vhal_proto::EmulatorMessage const& msg);
+
+   protected:
+    std::unique_ptr<std::thread> mReadThread;
+    MessageProcessor* mMessageProcessor;
+
+    /**
+     * A thread that reads messages in a loop, and responds. You can stop this thread by calling
+     * stop().
+     */
+    void readThread();
+};
+
+}  // namespace impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_EMULATORCOMMCONN_COMMCONN_H
diff --git a/emulator/Conn/PipeComm/Android.bp b/emulator/Conn/PipeComm/Android.bp
new file mode 100644
index 0000000..6f8e3b4
--- /dev/null
+++ b/emulator/Conn/PipeComm/Android.bp
@@ -0,0 +1,35 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// 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.
+
+package {
+    default_applicable_licenses: ["device_generic_car_license"],
+}
+
+cc_library {
+    name: "EmulatorPipeComm",
+    vendor: true,
+    srcs: [
+        "*.cpp",
+    ],
+    shared_libs: [
+        "libbase",
+        "liblog",
+        "libprotobuf-cpp-lite",
+    ],
+    export_include_dirs: ["include"],
+    static_libs: [
+        "android.hardware.automotive.vehicle@2.0-libproto-native",
+        "EmulatorCommConn",
+    ],
+}
diff --git a/emulator/Conn/PipeComm/PipeComm.cpp b/emulator/Conn/PipeComm/PipeComm.cpp
new file mode 100644
index 0000000..c54bf9f
--- /dev/null
+++ b/emulator/Conn/PipeComm/PipeComm.cpp
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "PipeComm"
+
+#include <log/log.h>
+
+#include "qemu_pipe.h"
+
+#include "PipeComm.h"
+
+#define CAR_SERVICE_NAME "pipe:qemud:car"
+
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+PipeComm::PipeComm(MessageProcessor* messageProcessor) : CommConn(messageProcessor), mPipeFd(-1) {}
+
+void PipeComm::start() {
+    int fd = qemu_pipe_open(CAR_SERVICE_NAME);
+
+    if (fd < 0) {
+        ALOGE("%s: Could not open connection to service: %s %d", __FUNCTION__, strerror(errno), fd);
+        return;
+    }
+
+    ALOGI("%s: Starting pipe connection, fd=%d", __FUNCTION__, fd);
+    mPipeFd = fd;
+
+    CommConn::start();
+}
+
+void PipeComm::stop() {
+    if (mPipeFd > 0) {
+        ::close(mPipeFd);
+        mPipeFd = -1;
+    }
+    CommConn::stop();
+}
+
+std::vector<uint8_t> PipeComm::read() {
+    static constexpr int MAX_RX_MSG_SZ = 2048;
+    std::vector<uint8_t> msg = std::vector<uint8_t>(MAX_RX_MSG_SZ);
+    int numBytes;
+
+    numBytes = qemu_pipe_frame_recv(mPipeFd, msg.data(), msg.size());
+
+    if (numBytes == MAX_RX_MSG_SZ) {
+        ALOGE("%s: Received max size = %d", __FUNCTION__, MAX_RX_MSG_SZ);
+    } else if (numBytes > 0) {
+        msg.resize(numBytes);
+        return msg;
+    } else {
+        ALOGD("%s: Connection terminated on pipe %d, numBytes=%d", __FUNCTION__, mPipeFd, numBytes);
+        mPipeFd = -1;
+    }
+
+    return std::vector<uint8_t>();
+}
+
+int PipeComm::write(const std::vector<uint8_t>& data) {
+    int retVal = 0;
+
+    if (mPipeFd != -1) {
+        retVal = qemu_pipe_frame_send(mPipeFd, data.data(), data.size());
+    }
+
+    if (retVal < 0) {
+        retVal = -errno;
+        ALOGE("%s:  send_cmd: (fd=%d): ERROR: %s", __FUNCTION__, mPipeFd, strerror(errno));
+    }
+
+    return retVal;
+}
+
+
+}  // impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+
+
diff --git a/emulator/Conn/PipeComm/include/PipeComm.h b/emulator/Conn/PipeComm/include/PipeComm.h
new file mode 100644
index 0000000..24dd686
--- /dev/null
+++ b/emulator/Conn/PipeComm/include/PipeComm.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef ANDROID_EMULATORPIPECOMM_PIPECOMM_H
+#define ANDROID_EMULATORPIPECOMM_PIPECOMM_H
+
+#include <mutex>
+#include <vector>
+
+#include "CommConn.h"
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+/**
+ * PipeComm opens a qemu pipe to connect to the emulator, allowing the emulator UI to access the
+ * Vehicle HAL and simulate changing properties.
+ *
+ * Since the pipe is a client, it directly implements CommConn, and only one PipeComm can be open
+ * at a time.
+ */
+class PipeComm : public CommConn {
+   public:
+    PipeComm(MessageProcessor* messageProcessor);
+
+    void start() override;
+    void stop() override;
+
+    std::vector<uint8_t> read() override;
+    int write(const std::vector<uint8_t>& data) override;
+
+    inline bool isOpen() override { return mPipeFd > 0; }
+
+   private:
+    int mPipeFd;
+};
+
+}  // impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_EMULATORPIPECOMM_PIPECOMM_H
diff --git a/emulator/Conn/PipeComm/include/qemu_pipe.h b/emulator/Conn/PipeComm/include/qemu_pipe.h
new file mode 100644
index 0000000..bd3e71d
--- /dev/null
+++ b/emulator/Conn/PipeComm/include/qemu_pipe.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef ANDROID_EMULATORPIPECOMM_QEMU_PIPE_H
+#define ANDROID_EMULATORPIPECOMM_QEMU_PIPE_H
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+// Try to open a new Qemu fast-pipe. This function returns a file descriptor
+// that can be used to communicate with a named service managed by the
+// emulator.
+//
+// This file descriptor can be used as a standard pipe/socket descriptor.
+//
+// 'pipeName' is the name of the emulator service you want to connect to,
+// and should begin with 'pipe:' (e.g. 'pipe:camera' or 'pipe:opengles').
+// For backward compatibility, the 'pipe:' prefix can be omitted, and in
+// that case, qemu_pipe_open will add it for you.
+
+// On success, return a valid file descriptor, or -1/errno on failure. E.g.:
+//
+// EINVAL  -> unknown/unsupported pipeName
+// ENOSYS  -> fast pipes not available in this system.
+//
+// ENOSYS should never happen, except if you're trying to run within a
+// misconfigured emulator.
+//
+// You should be able to open several pipes to the same pipe service,
+// except for a few special cases (e.g. GSM modem), where EBUSY will be
+// returned if more than one client tries to connect to it.
+int qemu_pipe_open(const char* pipeName);
+
+// Send a framed message |buff| of |len| bytes through the |fd| descriptor.
+// This really adds a 4-hexchar prefix describing the payload size.
+// Returns 0 on success, and -1 on error.
+int qemu_pipe_frame_send(int fd, const void* buff, size_t len);
+
+// Read a frame message from |fd|, and store it into |buff| of |len| bytes.
+// If the framed message is larger than |len|, then this returns -1 and the
+// content is lost. Otherwise, this returns the size of the message. NOTE:
+// empty messages are possible in a framed wire protocol and do not mean
+// end-of-stream.
+int qemu_pipe_frame_recv(int fd, void* buff, size_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // ANDROID_EMULATORPIPECOMM_QEMU_PIPE_H
diff --git a/emulator/Conn/PipeComm/qemu_pipe.cpp b/emulator/Conn/PipeComm/qemu_pipe.cpp
new file mode 100644
index 0000000..1f541b5
--- /dev/null
+++ b/emulator/Conn/PipeComm/qemu_pipe.cpp
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <android-base/file.h>
+
+#include "qemu_pipe.h"
+
+using android::base::ReadFully;
+using android::base::WriteFully;
+
+// Define QEMU_PIPE_DEBUG if you want to print error messages when an error
+// occurs during pipe operations. The macro should simply take a printf-style
+// formatting string followed by optional arguments.
+#ifndef QEMU_PIPE_DEBUG
+#define QEMU_PIPE_DEBUG(...) (void)0
+#endif
+
+int qemu_pipe_open(const char* pipeName) {
+    if (!pipeName) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    int fd = TEMP_FAILURE_RETRY(open("/dev/qemu_pipe", O_RDWR));
+    if (fd < 0) {
+        QEMU_PIPE_DEBUG("%s: Could not open /dev/qemu_pipe: %s", __FUNCTION__, strerror(errno));
+        return -1;
+    }
+
+    // Write the pipe name, *including* the trailing zero which is necessary.
+    size_t pipeNameLen = strlen(pipeName);
+    if (WriteFully(fd, pipeName, pipeNameLen + 1U)) {
+        return fd;
+    }
+
+    // now, add 'pipe:' prefix and try again
+    // Note: host side will wait for the trailing '\0' to start
+    // service lookup.
+    const char pipe_prefix[] = "pipe:";
+    if (WriteFully(fd, pipe_prefix, strlen(pipe_prefix)) &&
+        WriteFully(fd, pipeName, pipeNameLen + 1U)) {
+        return fd;
+    }
+    QEMU_PIPE_DEBUG("%s: Could not write to %s pipe service: %s", __FUNCTION__, pipeName,
+                    strerror(errno));
+    close(fd);
+    return -1;
+}
+
+int qemu_pipe_frame_send(int fd, const void* buff, size_t len) {
+    char header[5];
+    snprintf(header, sizeof(header), "%04zx", len);
+    if (!WriteFully(fd, header, 4)) {
+        QEMU_PIPE_DEBUG("Can't write qemud frame header: %s", strerror(errno));
+        return -1;
+    }
+    if (!WriteFully(fd, buff, len)) {
+        QEMU_PIPE_DEBUG("Can't write qemud frame payload: %s", strerror(errno));
+        return -1;
+    }
+    return 0;
+}
+
+int qemu_pipe_frame_recv(int fd, void* buff, size_t len) {
+    char header[5];
+    if (!ReadFully(fd, header, 4)) {
+        QEMU_PIPE_DEBUG("Can't read qemud frame header: %s", strerror(errno));
+        return -1;
+    }
+    header[4] = '\0';
+    size_t size;
+    if (sscanf(header, "%04zx", &size) != 1) {
+        QEMU_PIPE_DEBUG("Malformed qemud frame header: [%.*s]", 4, header);
+        return -1;
+    }
+    if (size > len) {
+        QEMU_PIPE_DEBUG("Oversized qemud frame (% bytes, expected <= %)", size, len);
+        return -1;
+    }
+    if (!ReadFully(fd, buff, size)) {
+        QEMU_PIPE_DEBUG("Could not read qemud frame payload: %s", strerror(errno));
+        return -1;
+    }
+    return size;
+}
diff --git a/emulator/Conn/SocketComm/Android.bp b/emulator/Conn/SocketComm/Android.bp
new file mode 100644
index 0000000..0a186d1
--- /dev/null
+++ b/emulator/Conn/SocketComm/Android.bp
@@ -0,0 +1,34 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// 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.
+
+package {
+    default_applicable_licenses: ["device_generic_car_license"],
+}
+
+cc_library {
+    name: "EmulatorSocketComm",
+    vendor: true,
+    srcs: [
+        "*.cpp",
+    ],
+    shared_libs: [
+        "liblog",
+        "libprotobuf-cpp-lite",
+    ],
+    export_include_dirs: ["include"],
+    static_libs: [
+        "android.hardware.automotive.vehicle@2.0-libproto-native",
+        "EmulatorCommConn",
+    ],
+}
diff --git a/emulator/Conn/SocketComm/SocketComm.cpp b/emulator/Conn/SocketComm/SocketComm.cpp
new file mode 100644
index 0000000..1e9a9bd
--- /dev/null
+++ b/emulator/Conn/SocketComm/SocketComm.cpp
@@ -0,0 +1,225 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "SocketComm"
+
+#include <android/log.h>
+#include <arpa/inet.h>
+#include <log/log.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "SocketComm.h"
+
+// Socket to use when communicating with Host PC
+static constexpr int DEBUG_SOCKET = 33452;
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+SocketComm::SocketComm(MessageProcessor* messageProcessor)
+    : mListenFd(-1), mMessageProcessor(messageProcessor) {}
+
+SocketComm::~SocketComm() {
+}
+
+void SocketComm::start() {
+    if (!listen()) {
+        return;
+    }
+
+    mListenThread = std::make_unique<std::thread>(std::bind(&SocketComm::listenThread, this));
+}
+
+void SocketComm::stop() {
+    if (mListenFd > 0) {
+        ::close(mListenFd);
+        if (mListenThread->joinable()) {
+            mListenThread->join();
+        }
+        mListenFd = -1;
+    }
+}
+
+void SocketComm::sendMessage(vhal_proto::EmulatorMessage const& msg) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    for (std::unique_ptr<SocketConn> const& conn : mOpenConnections) {
+        conn->sendMessage(msg);
+    }
+}
+
+bool SocketComm::listen() {
+    int retVal;
+    struct sockaddr_in servAddr;
+
+    mListenFd = socket(AF_INET, SOCK_STREAM, 0);
+    if (mListenFd < 0) {
+        ALOGE("%s: socket() failed, mSockFd=%d, errno=%d", __FUNCTION__, mListenFd, errno);
+        mListenFd = -1;
+        return false;
+    }
+
+    memset(&servAddr, 0, sizeof(servAddr));
+    servAddr.sin_family = AF_INET;
+    servAddr.sin_addr.s_addr = INADDR_ANY;
+    servAddr.sin_port = htons(DEBUG_SOCKET);
+
+    retVal = bind(mListenFd, reinterpret_cast<struct sockaddr*>(&servAddr), sizeof(servAddr));
+    if(retVal < 0) {
+        ALOGE("%s: Error on binding: retVal=%d, errno=%d", __FUNCTION__, retVal, errno);
+        close(mListenFd);
+        mListenFd = -1;
+        return false;
+    }
+
+    ALOGI("%s: Listening for connections on port %d", __FUNCTION__, DEBUG_SOCKET);
+    if (::listen(mListenFd, 1) == -1) {
+        ALOGE("%s: Error on listening: errno: %d: %s", __FUNCTION__, errno, strerror(errno));
+        return false;
+    }
+    return true;
+}
+
+SocketConn* SocketComm::accept() {
+    sockaddr_in cliAddr;
+    socklen_t cliLen = sizeof(cliAddr);
+    int sfd = ::accept(mListenFd, reinterpret_cast<struct sockaddr*>(&cliAddr), &cliLen);
+
+    if (sfd > 0) {
+        char addr[INET_ADDRSTRLEN];
+        inet_ntop(AF_INET, &cliAddr.sin_addr, addr, INET_ADDRSTRLEN);
+
+        ALOGD("%s: Incoming connection received from %s:%d", __FUNCTION__, addr, cliAddr.sin_port);
+        return new SocketConn(mMessageProcessor, sfd);
+    }
+
+    return nullptr;
+}
+
+void SocketComm::listenThread() {
+    while (true) {
+        SocketConn* conn = accept();
+        if (conn == nullptr) {
+            return;
+        }
+
+        conn->start();
+        {
+            std::lock_guard<std::mutex> lock(mMutex);
+            mOpenConnections.push_back(std::unique_ptr<SocketConn>(conn));
+        }
+    }
+}
+
+/**
+ * Called occasionally to clean up connections that have been closed.
+ */
+void SocketComm::removeClosedConnections() {
+    std::lock_guard<std::mutex> lock(mMutex);
+    std::remove_if(mOpenConnections.begin(), mOpenConnections.end(),
+                   [](std::unique_ptr<SocketConn> const& c) { return !c->isOpen(); });
+}
+
+SocketConn::SocketConn(MessageProcessor* messageProcessor, int sfd)
+    : CommConn(messageProcessor), mSockFd(sfd) {}
+
+/**
+ * Reads, in a loop, exactly numBytes from the given fd. If the connection is closed, returns
+ * an empty buffer, otherwise will return exactly the given number of bytes.
+ */
+std::vector<uint8_t> readExactly(int fd, int numBytes) {
+    std::vector<uint8_t> buffer(numBytes);
+    int totalRead = 0;
+    int offset = 0;
+    while (totalRead < numBytes) {
+        int numRead = ::read(fd, &buffer.data()[offset], numBytes - offset);
+        if (numRead == 0) {
+            buffer.resize(0);
+            return buffer;
+        }
+
+        totalRead += numRead;
+    }
+    return buffer;
+}
+
+/**
+ * Reads an int, guaranteed to be non-zero, from the given fd. If the connection is closed, returns
+ * -1.
+ */
+int32_t readInt(int fd) {
+    std::vector<uint8_t> buffer = readExactly(fd, sizeof(int32_t));
+    if (buffer.size() == 0) {
+        return -1;
+    }
+
+    int32_t value = *reinterpret_cast<int32_t*>(buffer.data());
+    return ntohl(value);
+}
+
+std::vector<uint8_t> SocketConn::read() {
+    int32_t msgSize = readInt(mSockFd);
+    if (msgSize <= 0) {
+        ALOGD("%s: Connection terminated on socket %d", __FUNCTION__, mSockFd);
+        return std::vector<uint8_t>();
+    }
+
+    return readExactly(mSockFd, msgSize);
+}
+
+void SocketConn::stop() {
+    if (mSockFd > 0) {
+        close(mSockFd);
+        mSockFd = -1;
+    }
+}
+
+int SocketConn::write(const std::vector<uint8_t>& data) {
+    static constexpr int MSG_HEADER_LEN = 4;
+    int retVal = 0;
+    union {
+        uint32_t msgLen;
+        uint8_t msgLenBytes[MSG_HEADER_LEN];
+    };
+
+    // Prepare header for the message
+    msgLen = static_cast<uint32_t>(data.size());
+    msgLen = htonl(msgLen);
+
+    if (mSockFd > 0) {
+        retVal = ::write(mSockFd, msgLenBytes, MSG_HEADER_LEN);
+
+        if (retVal == MSG_HEADER_LEN) {
+            retVal = ::write(mSockFd, data.data(), data.size());
+        }
+    }
+
+    return retVal;
+}
+
+}  // impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
diff --git a/emulator/Conn/SocketComm/include/SocketComm.h b/emulator/Conn/SocketComm/include/SocketComm.h
new file mode 100644
index 0000000..0664747
--- /dev/null
+++ b/emulator/Conn/SocketComm/include/SocketComm.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef ANDROID_EMULATORSOCKETCOMM_SOCKETCOMM_H
+#define ANDROID_EMULATORSOCKETCOMM_SOCKETCOMM_H
+
+#include <mutex>
+#include <thread>
+#include <vector>
+#include "CommConn.h"
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace V2_0 {
+
+namespace impl {
+
+class SocketConn;
+
+/**
+ * SocketComm opens a socket, and listens for connections from clients. Typically the client will be
+ * adb's TCP port-forwarding to enable a host PC to connect to the VehicleHAL.
+ */
+class SocketComm {
+   public:
+    SocketComm(MessageProcessor* messageProcessor);
+    virtual ~SocketComm();
+
+    void start();
+    void stop();
+
+    /**
+     * Serialized and send the given message to all connected clients.
+     */
+    void sendMessage(vhal_proto::EmulatorMessage const& msg);
+
+   private:
+    int mListenFd;
+    std::unique_ptr<std::thread> mListenThread;
+    std::vector<std::unique_ptr<SocketConn>> mOpenConnections;
+    MessageProcessor* mMessageProcessor;
+    std::mutex mMutex;
+
+    /**
+     * Opens the socket and begins listening.
+     *
+     * @return bool Returns true on success.
+     */
+    bool listen();
+
+    /**
+     * Blocks and waits for a connection from a client, returns a new SocketConn with the connection
+     * or null, if the connection has been closed.
+     *
+     * @return int Returns fd or socket number if connection is successful.
+     *              Otherwise, returns -1 if no connection is available.
+     */
+    SocketConn* accept();
+
+    void listenThread();
+
+    void removeClosedConnections();
+};
+
+/**
+ * SocketConn represents a single connection to a client.
+ */
+class SocketConn : public CommConn {
+   public:
+    SocketConn(MessageProcessor* messageProcessor, int sfd);
+    virtual ~SocketConn() = default;
+
+    /**
+     * Blocking call to read data from the connection.
+     *
+     * @return std::vector<uint8_t> Serialized protobuf data received from emulator.  This will be
+     *              an empty vector if the connection was closed or some other error occurred.
+     */
+    std::vector<uint8_t> read() override;
+
+    /**
+     * Closes a connection if it is open.
+     */
+    void stop() override;
+
+    /**
+     * Transmits a string of data to the emulator.
+     *
+     * @param data Serialized protobuf data to transmit.
+     *
+     * @return int Number of bytes transmitted, or -1 if failed.
+     */
+    int write(const std::vector<uint8_t>& data) override;
+
+    inline bool isOpen() override { return mSockFd > 0; }
+
+   private:
+    int mSockFd;
+};
+
+}  // impl
+
+}  // namespace V2_0
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_EMULATORSOCKETCOMM_SOCKETCOMM_H