Implement L2CAP service

Author: zxzxwu

bumble/pandora/__init__.py

@@ -26,11 +26,13 @@
 from .device import PandoraDevice
 from .host import HostService
 from .security import SecurityService, SecurityStorageService
+from .l2cap import L2CAPService
 from pandora.host_grpc_aio import add_HostServicer_to_server
 from pandora.security_grpc_aio import (
     add_SecurityServicer_to_server,
     add_SecurityStorageServicer_to_server,
 )
+from pandora.l2cap_grpc_aio import add_L2CAPServicer_to_server
 from typing import Callable, List, Optional
 
 # public symbols
@@ -77,6 +79,7 @@ async def serve(
             add_SecurityStorageServicer_to_server(
                 SecurityStorageService(bumble.device, config), server
             )
+            add_L2CAPServicer_to_server(L2CAPService(bumble.device, config), server)
 
             # call hooks if any.
             for hook in _SERVICERS_HOOKS:

bumble/pandora/l2cap.py

@@ -0,0 +1,322 @@
+# Copyright 2023 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.
+
+import abc
+import asyncio
+import collections
+import dataclasses
+import grpc
+import logging
+import struct
+
+from bumble import device
+from bumble import l2cap
+from bumble.utils import EventWatcher
+from bumble.pandora import config
+from bumble.pandora import utils
+from google.protobuf import any_pb2  # pytype: disable=pyi-error
+from google.protobuf import empty_pb2  # pytype: disable=pyi-error
+from pandora import l2cap_pb2
+from pandora import l2cap_grpc_aio
+from typing import AsyncGenerator, Dict, Union, Optional, DefaultDict
+
+
+class ChannelProxy(abc.ABC):
+    up_queue: asyncio.Queue[bytes] = asyncio.Queue()
+
+    def send(self, sdu: bytes) -> None:
+        ...
+
+    async def receive(self) -> bytes:
+        return await self.up_queue.get()
+
+    def on_data(self, pdu: bytes) -> None:
+        self.up_queue.put_nowait(pdu)
+
+
+class CocChannelProxy(ChannelProxy):
+    def __init__(
+        self, channel: Union[l2cap.ClassicChannel, l2cap.LeCreditBasedChannel]
+    ) -> None:
+        super().__init__()
+        self.channel = channel
+        channel.sink = self.on_data
+        self.disconnection_result = asyncio.get_event_loop().create_future()
+
+        @channel.once('close')
+        def on_close() -> None:
+            self.disconnection_result.set_result(None)
+
+    def send(self, data: bytes) -> None:
+        if isinstance(self.channel, l2cap.ClassicChannel):
+            self.channel.send_pdu(data)
+        else:
+            self.channel.write(data)
+
+    @property
+    def closed(self):
+        if isinstance(self.channel, l2cap.ClassicChannel):
+            return self.channel.state == self.channel.State.CLOSED
+        else:
+            return self.channel.state == self.channel.State.DISCONNECTED
+
+    async def disconnect(self) -> None:
+        if self.closed:
+            return
+
+        await self.channel.disconnect()
+
+    async def wait_disconnect(self) -> None:
+        if self.closed:
+            return
+
+        await self.disconnection_result
+
+
+@dataclasses.dataclass
+class FixedChannelProxy(ChannelProxy):
+    connection_handle: int
+    cid: int
+    device: device.Device
+
+    def send(self, data: bytes) -> None:
+        self.device.send_l2cap_pdu(self.connection_handle, self.cid, data)
+
+
+class L2CAPService(l2cap_grpc_aio.L2CAPServicer):
+    channels: DefaultDict[int, Dict[int, ChannelProxy]]
+
+    def __init__(self, device: device.Device, config: config.Config) -> None:
+        self.log = utils.BumbleServerLoggerAdapter(
+            logging.getLogger(), {'service_name': 'L2CAP', 'device': device}
+        )
+        self.device = device
+        self.config = config
+        self.channels = collections.defaultdict(dict)
+        self.device.on('connection', self.on_acl)
+
+    def on_acl(self, connection: device.Connection) -> None:
+        def on_disconnection(_reason) -> None:
+            del self.channels[connection.handle]
+
+        connection.once('disconnection', on_disconnection)
+
+    def get_channel(self, channel: l2cap_pb2.Channel) -> ChannelProxy:
+        connection_handle, cid = struct.unpack('>HH', channel.cookie.value)
+        if cid not in self.channels[connection_handle]:
+            raise RuntimeError('No valid cid or handle')
+        return self.channels[connection_handle][cid]
+
+    @utils.rpc
+    async def Connect(
+        self, request: l2cap_pb2.ConnectRequest, context: grpc.ServicerContext
+    ) -> l2cap_pb2.ConnectResponse:
+        self.log.debug('Connect')
+        channel: Union[
+            FixedChannelProxy, l2cap.ClassicChannel, l2cap.LeCreditBasedChannel
+        ]
+        connection_handle = int.from_bytes(request.connection.cookie.value, 'big')
+
+        connection = self.device.lookup_connection(connection_handle)
+        if connection is None:
+            raise RuntimeError('Connection not exist')
+
+        if request.type_variant() == 'fixed':
+            # For fixed channel connection, do nothing because it's connectionless
+            assert request.fixed
+            cid = request.fixed.cid
+            l2cap_cookie = any_pb2.Any(value=struct.pack('>HH', connection_handle, cid))
+            self.channels[connection_handle][cid] = FixedChannelProxy(
+                connection_handle=connection_handle,
+                cid=cid,
+                device=self.device,
+            )
+
+            def on_fixed_pdu(connection_handle: int, pdu: bytes) -> None:
+                self.channels[connection_handle][cid].on_data(pdu)
+
+            self.device.l2cap_channel_manager.register_fixed_channel(cid, on_fixed_pdu)
+            return l2cap_pb2.ConnectResponse(
+                channel=l2cap_pb2.Channel(cookie=l2cap_cookie)
+            )
+
+        if request.type_variant() == 'basic':
+            assert request.basic
+            channel = await connection.create_l2cap_channel(
+                spec=l2cap.ClassicChannelSpec(
+                    psm=request.basic.psm, mtu=request.basic.mtu
+                )
+            )
+        elif request.type_variant() == 'le_credit_based':
+            assert request.le_credit_based
+            channel = await connection.create_l2cap_channel(
+                spec=l2cap.LeCreditBasedChannelSpec(
+                    psm=request.le_credit_based.spsm,
+                    max_credits=request.le_credit_based.initial_credit,
+                    mtu=request.le_credit_based.mtu,
+                    mps=request.le_credit_based.mps,
+                )
+            )
+        else:
+            raise NotImplementedError()
+
+        self.channels[connection_handle][channel.source_cid] = CocChannelProxy(channel)
+        l2cap_cookie = any_pb2.Any(
+            value=struct.pack('>HH', connection_handle, channel.source_cid)
+        )
+        return l2cap_pb2.ConnectResponse(channel=l2cap_pb2.Channel(cookie=l2cap_cookie))
+
+    @utils.rpc
+    async def OnConnection(
+        self, request: l2cap_pb2.OnConnectionRequest, context: grpc.ServicerContext
+    ) -> AsyncGenerator[l2cap_pb2.OnConnectionResponse, None]:
+        self.log.debug('WaitConnection')
+
+        queue: asyncio.Queue[l2cap_pb2.OnConnectionResponse] = asyncio.Queue()
+
+        watcher = EventWatcher()
+        server: Union[
+            l2cap.ClassicChannelServer, l2cap.LeCreditBasedChannelServer, None
+        ] = None
+        fixed_cid: Optional[int] = None
+
+        # Fixed channels are connectionless, so it should produce a response immediately.
+        if request.type_variant() == 'fixed':
+            assert request.fixed
+            fixed_cid = request.fixed.cid
+
+            def on_fixed_pdu(connection_handle: int, pdu: bytes) -> None:
+                self.channels[connection_handle][fixed_cid].on_data(pdu)
+
+                channel_proxy = FixedChannelProxy(
+                    connection_handle=connection_handle,
+                    cid=fixed_cid,
+                    device=self.device,
+                )
+                self.channels[connection_handle][fixed_cid] = channel_proxy
+                l2cap_cookie = any_pb2.Any(
+                    value=struct.pack('>HH', connection_handle, fixed_cid)
+                )
+
+                queue.put_nowait(
+                    l2cap_pb2.OnConnectionResponse(
+                        channel=l2cap_pb2.Channel(cookie=l2cap_cookie)
+                    )
+                )
+
+            # Register CID and callback
+            self.device.l2cap_channel_manager.register_fixed_channel(
+                fixed_cid, on_fixed_pdu
+            )
+        else:
+
+            def on_connected(
+                channel: Union[l2cap.ClassicChannel, l2cap.LeCreditBasedChannel]
+            ) -> None:
+                connection_handle = channel.connection.handle
+
+                # Save channel instances
+                cid = channel.source_cid
+                self.channels[connection_handle][cid] = CocChannelProxy(channel)
+
+                # Produce connection responses
+                l2cap_cookie = any_pb2.Any(
+                    value=struct.pack('>HH', connection_handle, cid)
+                )
+                queue.put_nowait(
+                    l2cap_pb2.OnConnectionResponse(
+                        channel=l2cap_pb2.Channel(cookie=l2cap_cookie)
+                    )
+                )
+
+                # Listen disconnections
+                @watcher.on(channel, 'close')
+                def on_close():
+                    del self.channels[connection_handle][cid]
+
+            if request.type_variant() == 'basic':
+                assert request.basic
+                server = self.device.create_l2cap_server(
+                    spec=l2cap.ClassicChannelSpec(psm=request.basic.psm),
+                    handler=on_connected,
+                )
+            elif request.type_variant() == 'le_credit_based':
+                assert request.le_credit_based
+                server = self.device.create_l2cap_server(
+                    spec=l2cap.LeCreditBasedChannelSpec(
+                        psm=request.le_credit_based.spsm,
+                        max_credits=request.le_credit_based.initial_credit,
+                        mtu=request.le_credit_based.mtu,
+                        mps=request.le_credit_based.mps,
+                    ),
+                    handler=on_connected,
+                )
+            else:
+                raise NotImplementedError()
+
+        try:
+            # Produce event stream
+            while event := await queue.get():
+                yield event
+        finally:
+            watcher.close()
+            if server:
+                server.close()
+            if fixed_cid:
+                self.device.l2cap_channel_manager.deregister_fixed_channel(fixed_cid)
+
+    @utils.rpc
+    async def Disconnect(
+        self, request: l2cap_pb2.DisconnectRequest, context: grpc.ServicerContext
+    ) -> l2cap_pb2.DisconnectResponse:
+        self.log.debug('Disconnect')
+        channel = self.get_channel(request.channel)
+        if isinstance(channel, FixedChannelProxy):
+            raise ValueError('Fixed channel cannot be disconnected')
+
+        assert isinstance(channel, CocChannelProxy)
+        await channel.disconnect()
+        return l2cap_pb2.DisconnectResponse(success=empty_pb2.Empty())
+
+    @utils.rpc
+    async def WaitDisconnection(
+        self, request: l2cap_pb2.WaitDisconnectionRequest, context: grpc.ServicerContext
+    ) -> l2cap_pb2.WaitDisconnectionResponse:
+        self.log.debug('WaitDisconnection')
+        channel = self.get_channel(request.channel)
+        if isinstance(channel, FixedChannelProxy):
+            raise RuntimeError('Fixed channel cannot be disconnected')
+
+        assert isinstance(channel, CocChannelProxy)
+        await channel.wait_disconnect()
+        return l2cap_pb2.WaitDisconnectionResponse(success=empty_pb2.Empty())
+
+    @utils.rpc
+    async def Receive(
+        self, request: l2cap_pb2.ReceiveRequest, context: grpc.ServicerContext
+    ) -> AsyncGenerator[l2cap_pb2.ReceiveResponse, None]:
+        self.log.debug('Receive')
+        channel = self.get_channel(request.channel)
+
+        while packet := await channel.receive():
+            yield l2cap_pb2.ReceiveResponse(data=packet)
+
+    @utils.rpc
+    async def Send(
+        self, request: l2cap_pb2.SendRequest, context: grpc.ServicerContext
+    ) -> l2cap_pb2.SendResponse:
+        self.log.debug('Send')
+        channel = self.get_channel(request.channel)
+        channel.send(request.data)
+        return l2cap_pb2.SendResponse(success=empty_pb2.Empty())

setup.cfg

@@ -33,7 +33,7 @@ include_package_data = True
 install_requires =
     aiohttp ~= 3.8; platform_system!='Emscripten'
     appdirs >= 1.4; platform_system!='Emscripten'
-    bt-test-interfaces >= 0.0.2; platform_system!='Emscripten'
+    bt-test-interfaces >= 0.0.4; platform_system!='Emscripten'
     click == 8.1.3; platform_system!='Emscripten'
     cryptography == 39; platform_system!='Emscripten'
     # Pyodide bundles a version of cryptography that is built for wasm, which may not match the