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# 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 struct
import os
import socket
import ctypes
import collections
from .common import Transport, ParserSource
# -----------------------------------------------------------------------------
# Logging
# -----------------------------------------------------------------------------
logger = logging.getLogger(__name__)
# -----------------------------------------------------------------------------
async def open_hci_socket_transport(spec):
'''
Open an HCI Socket (only available on some platforms).
The parameter string is either empty (to use the first/default Bluetooth adapter)
or a 0-based integer to indicate the adapter number.
'''
HCI_CHANNEL_USER = 1 # pylint: disable=invalid-name
# Create a raw HCI socket
try:
hci_socket = socket.socket(
socket.AF_BLUETOOTH,
socket.SOCK_RAW | socket.SOCK_NONBLOCK,
socket.BTPROTO_HCI,
)
except AttributeError as error:
# Not supported on this platform
logger.info("HCI sockets not supported on this platform")
raise Exception(
'Bluetooth HCI sockets not supported on this platform'
) from error
# Compute the adapter index
if spec is None:
adapter_index = 0
else:
adapter_index = int(spec)
# Bind the socket
# NOTE: since Python doesn't support binding with the required address format (yet),
# we need to go directly to the C runtime...
try:
ctypes.cdll.LoadLibrary('libc.so.6')
libc = ctypes.CDLL('libc.so.6', use_errno=True)
except OSError as error:
logger.info("HCI sockets not supported on this platform")
raise Exception(
'Bluetooth HCI sockets not supported on this platform'
) from error
libc.bind.argtypes = (ctypes.c_int, ctypes.POINTER(ctypes.c_char), ctypes.c_int)
libc.bind.restype = ctypes.c_int
bind_address = struct.pack(
# pylint: disable=no-member
'<HHH',
socket.AF_BLUETOOTH,
adapter_index,
HCI_CHANNEL_USER,
)
if (
libc.bind(
hci_socket.fileno(),
ctypes.create_string_buffer(bind_address),
len(bind_address),
)
!= 0
):
raise IOError(ctypes.get_errno(), os.strerror(ctypes.get_errno()))
class HciSocketSource(ParserSource):
def __init__(self, hci_socket):
super().__init__()
self.socket = hci_socket
asyncio.get_running_loop().add_reader(
self.socket.fileno(), self.recv_until_would_block
)
def recv_until_would_block(self):
logger.debug('recv until would block +++')
while True:
try:
packet = self.socket.recv(4096)
logger.debug(f'received packet {len(packet)} bytes')
self.parser.feed_data(packet)
except BlockingIOError:
logger.debug('recv would block')
break
def close(self):
asyncio.get_running_loop().remove_reader(self.socket.fileno())
class HciSocketSink:
def __init__(self, hci_socket):
self.socket = hci_socket
self.packets = collections.deque()
self.writer_added = False
def send_until_would_block(self):
logger.debug('send until would block ---')
while self.packets:
packet = self.packets.pop()
logger.debug('sending packet')
try:
bytes_written = self.socket.send(packet)
except BlockingIOError:
bytes_written = 0
if bytes_written != len(packet):
# Note: we assume here that there are no partial writes
logger.debug('send would block')
break
if self.packets:
# There's still something to send, ensure that we are monitoring the
# socket
if not self.writer_added:
asyncio.get_running_loop().add_writer(
# pylint: disable=no-member
self.socket.fileno(),
self.send_until_would_block,
)
self.writer_added = True
else:
# Nothing left to send, stop monitoring the socket
if self.writer_added:
asyncio.get_running_loop().remove_writer(self.socket.fileno())
self.writer_added = False
def on_packet(self, packet):
self.packets.appendleft(packet)
self.send_until_would_block()
def close(self):
if self.writer_added:
asyncio.get_running_loop().remove_writer(self.socket.fileno())
class HciSocketTransport(Transport):
def __init__(self, hci_socket, source, sink):
super().__init__(source, sink)
self.socket = hci_socket
async def close(self):
logger.debug('closing HCI socket transport')
self.source.close()
self.sink.close()
self.socket.close()
packet_source = HciSocketSource(hci_socket)
packet_sink = HciSocketSink(hci_socket)
return HciSocketTransport(hci_socket, packet_source, packet_sink)
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