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#!/usr/bin/env python
"""
This script extracts btsnooz content from bugreports and generates
a valid btsnoop log file which can be viewed using standard tools
like Wireshark.
btsnooz is a custom format designed to be included in bugreports.
It can be described as:
base64 {
file_header
deflate {
repeated {
record_header
record_data
}
}
}
where the file_header and record_header are modified versions of
the btsnoop headers.
"""
import base64
import fileinput
import struct
import sys
import zlib
# Enumeration of the values the 'type' field can take in a btsnooz
# header. These values come from the Bluetooth stack's internal
# representation of packet types.
TYPE_IN_EVT = 0x10
TYPE_IN_ACL = 0x11
TYPE_IN_SCO = 0x12
TYPE_IN_ISO = 0x17
TYPE_OUT_CMD = 0x20
TYPE_OUT_ACL = 0x21
TYPE_OUT_SCO = 0x22
TYPE_OUT_ISO = 0x2d
def type_to_direction(type):
"""
Returns the inbound/outbound direction of a packet given its type.
0 = sent packet
1 = received packet
"""
if type in [TYPE_IN_EVT, TYPE_IN_ACL, TYPE_IN_SCO, TYPE_IN_ISO]:
return 1
return 0
def type_to_hci(type):
"""
Returns the HCI type of a packet given its btsnooz type.
"""
if type == TYPE_OUT_CMD:
return '\x01'
if type == TYPE_IN_ACL or type == TYPE_OUT_ACL:
return '\x02'
if type == TYPE_IN_SCO or type == TYPE_OUT_SCO:
return '\x03'
if type == TYPE_IN_EVT:
return '\x04'
if type == TYPE_IN_ISO or type == TYPE_OUT_ISO:
return '\x05'
raise RuntimeError("type_to_hci: unknown type (0x{:02x})".format(type))
def decode_snooz(snooz):
"""
Decodes all known versions of a btsnooz file into a btsnoop file.
"""
version, last_timestamp_ms = struct.unpack_from('=bQ', snooz)
if version != 1 and version != 2:
sys.stderr.write('Unsupported btsnooz version: %s\n' % version)
exit(1)
# Oddly, the file header (9 bytes) is not compressed, but the rest is.
decompressed = zlib.decompress(snooz[9:])
sys.stdout.write('btsnoop\x00\x00\x00\x00\x01\x00\x00\x03\xea')
if version == 1:
decode_snooz_v1(decompressed, last_timestamp_ms)
elif version == 2:
decode_snooz_v2(decompressed, last_timestamp_ms)
def decode_snooz_v1(decompressed, last_timestamp_ms):
"""
Decodes btsnooz v1 files into a btsnoop file.
"""
# An unfortunate consequence of the file format design: we have to do a
# pass of the entire file to determine the timestamp of the first packet.
first_timestamp_ms = last_timestamp_ms + 0x00dcddb30f2f8000
offset = 0
while offset < len(decompressed):
length, delta_time_ms, type = struct.unpack_from('=HIb', decompressed, offset)
offset += 7 + length - 1
first_timestamp_ms -= delta_time_ms
# Second pass does the actual writing out to stdout.
offset = 0
while offset < len(decompressed):
length, delta_time_ms, type = struct.unpack_from('=HIb', decompressed, offset)
first_timestamp_ms += delta_time_ms
offset += 7
sys.stdout.write(struct.pack('>II', length, length))
sys.stdout.write(struct.pack('>II', type_to_direction(type), 0))
sys.stdout.write(struct.pack('>II', (first_timestamp_ms >> 32), (first_timestamp_ms & 0xFFFFFFFF)))
sys.stdout.write(type_to_hci(type))
sys.stdout.write(decompressed[offset:offset + length - 1])
offset += length - 1
def decode_snooz_v2(decompressed, last_timestamp_ms):
"""
Decodes btsnooz v2 files into a btsnoop file.
"""
# An unfortunate consequence of the file format design: we have to do a
# pass of the entire file to determine the timestamp of the first packet.
first_timestamp_ms = last_timestamp_ms + 0x00dcddb30f2f8000
offset = 0
while offset < len(decompressed):
length, packet_length, delta_time_ms, snooz_type = struct.unpack_from('=HHIb', decompressed, offset)
offset += 9 + length - 1
first_timestamp_ms -= delta_time_ms
# Second pass does the actual writing out to stdout.
offset = 0
while offset < len(decompressed):
length, packet_length, delta_time_ms, snooz_type = struct.unpack_from('=HHIb', decompressed, offset)
first_timestamp_ms += delta_time_ms
offset += 9
sys.stdout.write(struct.pack('>II', packet_length, length))
sys.stdout.write(struct.pack('>II', type_to_direction(snooz_type), 0))
sys.stdout.write(struct.pack('>II', (first_timestamp_ms >> 32), (first_timestamp_ms & 0xFFFFFFFF)))
sys.stdout.write(type_to_hci(snooz_type))
sys.stdout.write(decompressed[offset:offset + length - 1])
offset += length - 1
def main():
if len(sys.argv) > 2:
sys.stderr.write('Usage: %s [bugreport]\n' % sys.argv[0])
exit(1)
iterator = fileinput.input()
found = False
base64_string = ""
for line in iterator:
if found:
if line.find('--- END:BTSNOOP_LOG_SUMMARY') != -1:
decode_snooz(base64.standard_b64decode(base64_string))
sys.exit(0)
base64_string += line.strip()
if line.find('--- BEGIN:BTSNOOP_LOG_SUMMARY') != -1:
found = True
if not found:
sys.stderr.write('No btsnooz section found in bugreport.\n')
sys.exit(1)
if __name__ == '__main__':
main()
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