examples/run_rfcomm_client.py

# 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 sys
import os
import logging

from colors import color
from bumble.device import Device
from bumble.transport import open_transport_or_link
from bumble.core import ConnectionError, BT_BR_EDR_TRANSPORT
from bumble.rfcomm import Client
from bumble.sdp import (
    Client as SDP_Client,
    DataElement,
    ServiceAttribute,
    SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
    SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
    SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID
)
from bumble.hci import BT_L2CAP_PROTOCOL_ID, BT_RFCOMM_PROTOCOL_ID


# -----------------------------------------------------------------------------
async def list_rfcomm_channels(device, connection):
    # Connect to the SDP Server
    sdp_client = SDP_Client(device)
    await sdp_client.connect(connection)

    # Search for services with an L2CAP service attribute
    search_result = await sdp_client.search_attributes(
        [BT_L2CAP_PROTOCOL_ID],
        [
            SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
            SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID,
            SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID
        ]
    )
    print(color('==================================', 'blue'))
    print(color('RFCOMM Services:', 'yellow'))
    for attribute_list in search_result:
        # Look for the RFCOMM Channel number
        protocol_descriptor_list = ServiceAttribute.find_attribute_in_list(
            attribute_list,
            SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID
        )
        if protocol_descriptor_list:
            for protocol_descriptor in protocol_descriptor_list.value:
                if len(protocol_descriptor.value) >= 2:
                    if protocol_descriptor.value[0].value == BT_RFCOMM_PROTOCOL_ID:
                        print(color('SERVICE:', 'green'))
                        print(color('  RFCOMM Channel:', 'cyan'), protocol_descriptor.value[1].value)

                        # List profiles
                        bluetooth_profile_descriptor_list = ServiceAttribute.find_attribute_in_list(
                            attribute_list,
                            SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID
                        )
                        if bluetooth_profile_descriptor_list:
                            if bluetooth_profile_descriptor_list.value:
                                if bluetooth_profile_descriptor_list.value[0].type == DataElement.SEQUENCE:
                                    bluetooth_profile_descriptors = bluetooth_profile_descriptor_list.value
                                else:
                                    # Sometimes, instead of a list of lists, we just find a list. Fix that
                                    bluetooth_profile_descriptors = [bluetooth_profile_descriptor_list]

                                print(color('  Profiles:', 'green'))
                                for bluetooth_profile_descriptor in bluetooth_profile_descriptors:
                                    version_major = bluetooth_profile_descriptor.value[1].value >> 8
                                    version_minor = bluetooth_profile_descriptor.value[1].value & 0xFF
                                    print(f'    {bluetooth_profile_descriptor.value[0].value} - version {version_major}.{version_minor}')

                        # List service classes
                        service_class_id_list = ServiceAttribute.find_attribute_in_list(
                            attribute_list,
                            SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID
                        )
                        if service_class_id_list:
                            if service_class_id_list.value:
                                print(color('  Service Classes:', 'green'))
                                for service_class_id in service_class_id_list.value:
                                    print('   ', service_class_id.value)

    await sdp_client.disconnect()

# -----------------------------------------------------------------------------
class TcpServerProtocol(asyncio.Protocol):
    def __init__(self, rfcomm_session):
        self.rfcomm_session = rfcomm_session

    def connection_made(self, transport):
        peername = transport.get_extra_info('peername')
        print(f'<<< TCP Server: connection from {peername}')
        self.transport = transport
        self.rfcomm_session.sink = self.rfcomm_data_received

    def rfcomm_data_received(self, data):
        print(f'<<< RFCOMM Data: {data.hex()}')
        if self.transport:
            self.transport.write(data)
        else:
            print('!!! no TCP connection, dropping data')

    def data_received(self, data):
        print(f'<<< TCP Server: data received: {len(data)} bytes - {data.hex()}')
        self.rfcomm_session.write(data)


# -----------------------------------------------------------------------------
async def tcp_server(tcp_port, rfcomm_session):
    print(f'$$$ Starting TCP server on port {tcp_port}')

    server = await asyncio.get_running_loop().create_server(
        lambda: TcpServerProtocol(rfcomm_session), '127.0.0.1', tcp_port
    )
    await asyncio.get_running_loop().create_future()

    async with server:
        await server.serve_forever()


# -----------------------------------------------------------------------------
async def main():
    if len(sys.argv) < 5:
        print('Usage: run_rfcomm_client.py <device-config> <transport-spec> <bluetooth-address> <channel>|discover [tcp-port]')
        print('  specifying a channel number, or "discover" to list all RFCOMM channels')
        print('example: run_rfcomm_client.py classic1.json usb:04b4:f901 E1:CA:72:48:C4:E8 8')
        return

    print('<<< connecting to HCI...')
    async with await open_transport_or_link(sys.argv[2]) as (hci_source, hci_sink):
        print('<<< connected')

        # Create a device
        device = Device.from_config_file_with_hci(sys.argv[1], hci_source, hci_sink)
        device.classic_enabled = True
        await device.power_on()

        # Connect to a peer
        target_address = sys.argv[3]
        print(f'=== Connecting to {target_address}...')
        connection = await device.connect(target_address, transport=BT_BR_EDR_TRANSPORT)
        print(f'=== Connected to {connection.peer_address}!')

        channel = sys.argv[4]
        if channel == 'discover':
            await list_rfcomm_channels(device, connection)
            return

        # Request authentication
        print('*** Authenticating...')
        await connection.authenticate()
        print('*** Authenticated')

        # Enable encryption
        print('*** Enabling encryption...')
        await connection.encrypt()
        print('*** Encryption on')

        # Create a client and start it
        print('@@@ Starting to RFCOMM client...')
        rfcomm_client = Client(device, connection)
        rfcomm_mux = await rfcomm_client.start()
        print('@@@ Started')

        channel = int(channel)
        print(f'### Opening session for channel {channel}...')
        try:
            session = await rfcomm_mux.open_dlc(channel)
            print('### Session open', session)
        except ConnectionError as error:
            print(f'### Session open failed: {error}')
            await rfcomm_mux.disconnect()
            print('@@@ Disconnected from RFCOMM server')
            return

        if len(sys.argv) == 6:
            # A TCP port was specified, start listening
            tcp_port = int(sys.argv[5])
            asyncio.get_running_loop().create_task(tcp_server(tcp_port, session))

        await hci_source.wait_for_termination()

# -----------------------------------------------------------------------------
logging.basicConfig(level = os.environ.get('BUMBLE_LOGLEVEL', 'DEBUG').upper())
asyncio.run(main())