From 302e496890e90678fcd593f2af23f9a939833cae Mon Sep 17 00:00:00 2001
From: Gilles Boccon-Gibod <bok@bok.net>
Date: Sat, 13 Dec 2025 16:27:04 -0800
Subject: [PATCH] android-netsim transport enhancements

---
 bumble/transport/android_netsim.py | 74 +++++++++++++++++-------------
 1 file changed, 42 insertions(+), 32 deletions(-)

diff --git a/bumble/transport/android_netsim.py b/bumble/transport/android_netsim.py
index 35653806..4a6a210c 100644
--- a/bumble/transport/android_netsim.py
+++ b/bumble/transport/android_netsim.py
@@ -156,21 +156,26 @@ async def open_android_netsim_controller_transport(
         logger.warning("unable to publish gRPC port")
 
     class HciDevice:
-        def __init__(self, context, on_data_received):
+        def __init__(self, context, server):
             self.context = context
-            self.on_data_received = on_data_received
+            self.server = server
             self.name = None
+            self.sink = None
             self.loop = asyncio.get_running_loop()
             self.done = self.loop.create_future()
-            self.task = self.loop.create_task(self.pump())
 
         async def pump(self):
             try:
                 await self.pump_loop()
             except asyncio.CancelledError:
                 logger.debug('Pump task canceled')
-                if not self.done.done():
-                    self.done.set_result(None)
+            finally:
+                if self.sink:
+                    logger.debug('Releasing sink')
+                    self.server.release_sink()
+                    self.sink = None
+
+                logger.debug('Pump task terminated')
 
         async def pump_loop(self):
             while True:
@@ -186,15 +191,26 @@ async def pump_loop(self):
                     if request.WhichOneof('request_type') == 'initial_info':
                         logger.debug(f'Received initial info: {request}')
 
+                        self.name = request.initial_info.name
+
                         # We only accept BLUETOOTH
                         if request.initial_info.chip.kind != ChipKind.BLUETOOTH:
                             logger.warning('Unsupported chip type')
                             error = PacketResponse(error='Unsupported chip type')
                             await self.context.write(error)
-                            return
+                            # return
+                            continue
+
+                        # Lease the sink so that no other device can send
+                        self.sink = self.server.lease_sink(self)
+                        if self.sink is None:
+                            logger.warning('Another device is already connected')
+                            error = PacketResponse(error='Device busy')
+                            await self.context.write(error)
+                            # return
+                            continue
 
-                    self.name = request.initial_info.name
-                    continue
+                        continue
 
                 # Expect a data packet
                 request_type = request.WhichOneof('request_type')
@@ -205,10 +221,10 @@ async def pump_loop(self):
                     continue
 
                 # Process the packet
-                data = (
+                assert self.sink is not None
+                self.sink(
                     bytes([request.hci_packet.packet_type]) + request.hci_packet.packet
                 )
-                self.on_data_received(data)
 
         async def send_packet(self, data):
             return await self.context.write(
@@ -217,12 +233,6 @@ async def send_packet(self, data):
                 )
             )
 
-        def terminate(self):
-            self.task.cancel()
-
-        async def wait_for_termination(self):
-            await self.done
-
     server_address = f'{server_host}:{server_port}'
 
     class Server(PacketStreamerServicer, ParserSource):
@@ -258,27 +268,27 @@ async def send_packet(self, packet):
 
             return await self.device.send_packet(packet)
 
-        async def StreamPackets(self, _request_iterator, context):
-            logger.debug('StreamPackets request')
-
-            # Check that we don't already have a device
+        def lease_sink(self, device):
             if self.device:
-                logger.debug('Busy, already serving a device')
-                return PacketResponse(error='Busy')
+                return None
+            self.device = device
+            return self.parser.feed_data
+
+        def release_sink(self):
+            self.device = None
+
+        async def StreamPackets(self, request_iterator, context):
+            logger.debug('StreamPackets request')
 
             # Instantiate a new device
-            self.device = HciDevice(context, self.parser.feed_data)
+            device = HciDevice(context, self)
 
-            # Wait for the device to terminate
-            logger.debug('Waiting for device to terminate')
+            # Pump packets to/from the device
+            logger.debug('Pumping device packets')
             try:
-                await self.device.wait_for_termination()
-            except asyncio.CancelledError:
-                logger.debug('Request canceled')
-                self.device.terminate()
-
-            logger.debug('Device terminated')
-            self.device = None
+                await device.pump()
+            finally:
+                logger.debug('Pump terminated')
 
     server = Server()
     await server.start()