address PR comments

apps/bench.py

@@ -50,8 +50,10 @@ from bumble.sdp import (
     SDP_PUBLIC_BROWSE_ROOT,
     SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
     SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
+    SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID,
     DataElement,
     ServiceAttribute,
+    Client as SdpClient,
 )
 from bumble.transport import open_transport_or_link
 import bumble.rfcomm
@@ -195,6 +197,50 @@ def make_sdp_records(channel):
     }
 
 
+async def find_rfcomm_channel_with_uuid(
+    device: Device, connection: Connection, uuid: str
+) -> int:
+    # Connect to the SDP Server
+    sdp_client = SdpClient(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,
+        ],
+    )
+    for attribute_list in search_result:
+        service_uuid = None
+        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:
+                for service_class_id in service_class_id_list.value:
+                    service_uuid = service_class_id.value
+        if str(service_uuid) != uuid:
+            # This service doesn't have a UUID or isn't the right one.
+            continue
+
+        # 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:
+                        await sdp_client.disconnect()
+                        return protocol_descriptor.value[1].value
+
+    await sdp_client.disconnect()
+    return 0
+
+
 class PacketType(enum.IntEnum):
     RESET = 0
     SEQUENCE = 1
@@ -747,24 +793,40 @@ class L2capServer(StreamedPacketIO):
 # RfcommClient
 # -----------------------------------------------------------------------------
 class RfcommClient(StreamedPacketIO):
-    def __init__(self, device, channel):
+    def __init__(self, device, channel, uuid):
         super().__init__()
         self.device = device
         self.channel = channel
+        self.uuid = uuid
         self.ready = asyncio.Event()
 
     async def on_connection(self, connection):
         connection.on('disconnection', self.on_disconnection)
 
+        # Find the channel number if not specified
+        channel = self.channel
+        if channel == 0:
+            print(
+                color(f'@@@ Discovering channel number from UUID {self.uuid}', 'cyan')
+            )
+            channel = await find_rfcomm_channel_with_uuid(
+                self.device, connection, self.uuid
+            )
+            print(color(f'@@@ Channel number = {channel}', 'cyan'))
+            if channel == 0:
+                print(color('!!! No RFComm service with this UUID found', 'red'))
+                await connection.disconnect()
+                return
+
         # Create a client and start it
         print(color('*** Starting RFCOMM client...', 'blue'))
         rfcomm_client = bumble.rfcomm.Client(self.device, connection)
         rfcomm_mux = await rfcomm_client.start()
         print(color('*** Started', 'blue'))
 
-        print(color(f'### Opening session for channel {self.channel}...', 'yellow'))
+        print(color(f'### Opening session for channel {channel}...', 'yellow'))
         try:
-            rfcomm_session = await rfcomm_mux.open_dlc(self.channel)
+            rfcomm_session = await rfcomm_mux.open_dlc(channel)
             print(color('### Session open', 'yellow'), rfcomm_session)
         except bumble.core.ConnectionError as error:
             print(color(f'!!! Session open failed: {error}', 'red'))
@@ -1087,7 +1149,9 @@ def create_mode_factory(ctx, default_mode):
             return L2capServer(device, psm=ctx.obj['l2cap_psm'])
 
         if mode == 'rfcomm-client':
-            return RfcommClient(device, channel=ctx.obj['rfcomm_channel'])
+            return RfcommClient(
+                device, channel=ctx.obj['rfcomm_channel'], uuid=ctx.obj['rfcomm_uuid']
+            )
 
         if mode == 'rfcomm-server':
             return RfcommServer(device, channel=ctx.obj['rfcomm_channel'])
@@ -1166,6 +1230,11 @@ def create_role_factory(ctx, default_role):
     default=DEFAULT_RFCOMM_CHANNEL,
     help='RFComm channel to use',
 )
+@click.option(
+    '--rfcomm-uuid',
+    default=DEFAULT_RFCOMM_UUID,
+    help='RFComm service UUID to use (ignored is --rfcomm-channel is not 0)',
+)
 @click.option(
     '--l2cap-psm',
     type=int,
@@ -1208,6 +1277,7 @@ def bench(
     packet_count,
     start_delay,
     rfcomm_channel,
+    rfcomm_uuid,
     l2cap_psm,
 ):
     ctx.ensure_object(dict)
@@ -1216,6 +1286,7 @@ def bench(
     ctx.obj['mode'] = mode
     ctx.obj['att_mtu'] = att_mtu
     ctx.obj['rfcomm_channel'] = rfcomm_channel
+    ctx.obj['rfcomm_uuid'] = rfcomm_uuid
     ctx.obj['l2cap_psm'] = l2cap_psm
     ctx.obj['packet_size'] = packet_size
     ctx.obj['packet_count'] = packet_count