aio-libs
Strange WebSocket behavior since version 3.7
Close code of WebSocket became different after upgrading aiohttp from version 3.6.3 to version 3.7.2.
$ python -V
Python 3.9.0
server.py:
from aiohttp import web
async def ws_handler(request):
ws = web.WebSocketResponse()
await ws.prepare(request)
print('Closing')
await ws.close()
return ws
app = web.Application()
app.add_routes([web.get('/ws', ws_handler)])
web.run_app(app, port=8888)
Server logs are the same for all versions of aiohttp.
client.py:
import asyncio
import aiohttp
async def main():
async with aiohttp.ClientSession() as session:
async with session.ws_connect('http://localhost:8888/ws') as ws:
print('Sending')
await ws.send_str('some data')
await asyncio.sleep(1)
print('Receiving')
await ws.receive()
print('Close code:', ws.close_code)
asyncio.run(main())
Client logs (aiohttp==3.6.3):
$ python client.py
Sending
Receiving
Close code: 1000
Client logs (aiohttp==3.7.2):
$ python client.py
Sending
Receiving
Close code: 1006
Timing issue? 1006 is set when pong is not received or the caller was cancelled.
@asvetlov No it's not. Here is the test to reproduce
async def test_ws_close_return_code(aiohttp_client) -> None:
async def handler(request):
ws = web.WebSocketResponse()
await ws.prepare(request)
await ws.close()
return ws
app = web.Application()
app.router.add_route("GET", "/", handler)
client = await aiohttp_client(app)
resp = await client.ws_connect("/")
await resp.send_str('some data')
await asyncio.sleep(0.1)
await resp.receive()
assert resp.close_code == WSCloseCode.OK
In client_ws.py it calls `close()' :
async def close(self, *, code: int = 1000, message: bytes = b"") -> bool:
# we need to break `receive()` cycle first,
# `close()` may be called from different task
if self._waiting is not None and not self._closed:
self._reader.feed_data(WS_CLOSING_MESSAGE, 0)
await self._waiting
if not self._closed:
self._cancel_heartbeat()
self._closed = True
try:
await self._writer.close(code, message)
except asyncio.CancelledError:
self._close_code = 1006
self._response.close()
raise
except Exception as exc: # <-- we come to this branch due to ConnectionResetError("Cannot write to closing transport") from WebSocketWriter
self._close_code = 1006
self._exception = exc
self._response.close()
return True
This overwrites the OK close code.
The real reason IMHO in overcomplicated (closing/closed boolean flags) logic of closing the ws. I would recommend to refactor it using finite state machine.
Reread you message again. Looks like your detection is right. Please let me keep the issue open for a while
WS client received the close message from the server and set the code to 1000. Then it tried to send/receive some data. But this action shouldn't overwrite the close code. Or it should?
WebSocket problems are on my radar but I have no capacity to analyze them right now. Sure, I'll go over all websocket issues and try to address them before 3.8 release
@bdraco Fancy another websocket one? Test is in https://github.com/aio-libs/aiohttp/issues/5180#issuecomment-720057199
Issue here is the client receives a Close frame, then tries to send a Close frame in response, but then hits this error:
../hacking/aiohttp/aiohttp/client_ws.py:360: in receive
await self.close()
../hacking/aiohttp/aiohttp/client_ws.py:264: in close
await self._writer.close(code, message)
../hacking/aiohttp/aiohttp/http_websocket.py:718: in close
await self._send_frame(
../hacking/aiohttp/aiohttp/http_websocket.py:657: in _send_frame
self._write(header + mask + message)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <aiohttp.http_websocket.WebSocketWriter object at 0x7f4c20d17ca0>, data = b'\x88\x82h!\x9e\xdak\xc9'
def _write(self, data: bytes) -> None:
if self.transport.is_closing():
> raise ConnectionResetError("Cannot write to closing transport")
E ConnectionResetError: Cannot write to closing transport
../hacking/aiohttp/aiohttp/http_websocket.py:684: ConnectionResetError
This suggests the server has closed the connection prematurely. The server should wait for the Close frame from the client before closing the connection: https://datatracker.ietf.org/doc/html/rfc6455#section-1.4
I’ll put it in my queue. Busy this week though so probably next weekend before I look
Note to self: Need to make sure we don't wait too long for a close frame that never comes as well. Probably needs a timeout for that if we don't already have one
It took me a while but I realized that this is behaving as expected because the client is sending a string await ws.send_str('some data') which is never received by the server (no receive), and the connection is closed while the message is still on the wire.
Hmm, I suppose that's a bit of an odd case. close() could maybe drain the buffer or something, but shouldn't really be happening in real use cases regardless.