OSError/simple_websocket.ws.ConnectionClosed: Connection closed: 1005 on disconnect during the connect event. #1958

Seluj78 · 2023-03-21T16:03:06Z

Seluj78
Mar 21, 2023

Hi,

First of all, thank you for your work !

Here is my setup:

import logging

from flask_socketio import emit, send, disconnect
from flask import request, session
from hub_backend import socketio
from flask_jwt_extended import decode_token
from jwt.exceptions import ExpiredSignatureError
from dst_datamodel import Users

socket_connections = {}


@socketio.on("connect")
def on_connect():
    token = request.args.get('token')
    if token is None:
        logging.info("Canceled connection without a token.")
        disconnect(request.sid)
        return

    try:
        data = decode_token(token)
    except ExpiredSignatureError:
        logging.info("User tried to connect with expired token.")
        disconnect(request.sid)
        return

    user_id = int(data['sub']['id'])
    if socket_connections.get(user_id):
        logging.info(f"Rejecting already opened session for user {user_id}.")
        disconnect(request.sid)
        return

    logging.info(f"Received SocketIO connection for user {user_id}.")
    try:
        user: Users = Users.get_by_id(user_id)
    except Users.DoesNotExist:
        logging.info(f"User {user_id} tried to connect to sockets but doesn't exist in database.")
        disconnect(request.sid)
        return

    if not user.is_active:
        logging.info(f"User {user_id} tried to connect to sockets but isn't active.")
        disconnect(request.sid)
        return

    socket_connections[user_id] = request.sid
    session["user_id"] = user_id
    session["sid"] = request.sid

    logging.info(f"SocketIO Auth success for user {user_id}.")
    send(f"Connection for user {user_id} is successful.")
    emit("ack", "Connection successfully received.")


@socketio.on("disconnect")
def on_disconnect():
    if 'user_id' in session:
        logging.info(f"User {session['user_id']} disconnected.")
        del socket_connections[session["user_id"]]


@socketio.on("message")
def handle_message(data):
    logging.info(f"Got message {data} with session {session} and request {request}.")
    logging.warning(socket_connections)


@socketio.on_error()
def error_handler(e):
    logging.warning(e)

@socketio.on_error_default
def default_error_handler(e):
    logging.warning(request.event["message"])
    logging.warning(request.event["args"])
    logging.warning(e)

And the definition of socketio (application is a normal Flask application.):

socketio = SocketIO(application, logger=True, engineio_logger=True)
socketio.init_app(application, cors_allowed_origins="*")

The server is ran using socketio.run(application, debug=True, port=5000).

Here is my client testing file:

<html>
    <head>
        <script src="https://cdn.socket.io/4.4.1/socket.io.min.js" integrity="sha384-fKnu0iswBIqkjxrhQCTZ7qlLHOFEgNkRmK2vaO/LbTZSXdJfAu6ewRBdwHPhBo/H" crossorigin="anonymous"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.4/jquery.min.js" integrity="sha512-pumBsjNRGGqkPzKHndZMaAG+bir374sORyzM3uulLV14lN5LyykqNk8eEeUlUkB3U0M4FApyaHraT65ihJhDpQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
    </head>
    <body>
        <button id="create_socket_connection">CONNECT</button>
        <button id="socket_disconnect">DISCONNECT</button>
        <button id="send_message">Send event</button>
        <script>
            var socket = null;

            $( "#create_socket_connection" ).click(function() {
                socket = new io(
                    'ws://localhost:5000', {
                        query: {
                            token: 'A JWT TOKEN'
                        }
                    }
                );
                socket.connect();

                socket.on("connect", () => {
                    console.log('\r\n*** Connected to API ***\r\n');
                });

                socket.on("message", (data) => {
                    console.log('data', data);
                });


                socket.on("disconnect", () => {
                    socket = null
                    console.log('\r\n*** Disconnected from API ***\r\n');
                })
            });

            $("#socket_disconnect").click(() => {
                socket.disconnect();
            })

            $("#send_message").click(() => {
                // socket.emit("notification", "all")
                if (socket) {
                    socket.send("Hello")
                }
            })
        </script>
    </body>
</html>

The idea behind this is, when the page is loaded (Not this simple html/js page, but a react frontend), a socketio connection is created betweeen the client (user, on the website) and the server (the backend, using Flask, flask-jwt-extended and flask-socketio.)

Everything is running great, except when I have an expired token sent in the query string, which might happen, so I want to close the connection because we cannot allow an unauthentified user to use the sockets.

When I use the Connect button on the html page, Here are the logs thrown by the Flask application.

5vuHkzT7GouFH86rAAAA: Sending packet OPEN data {'sid': '5vuHkzT7GouFH86rAAAA', 'upgrades': ['websocket'], 'pingTimeout': 20000, 'pingInterval': 25000}
{"message": "5vuHkzT7GouFH86rAAAA: Sending packet OPEN data {'sid': '5vuHkzT7GouFH86rAAAA', 'upgrades': ['websocket'], 'pingTimeout': 20000, 'pingInterval': 25000}", "username": null, "path": null, "ip": null, "filename": "socket.py", "funcName": "send", "levelname": "INFO", "lineno": 89, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.110472"}
{"message": "5vuHkzT7GouFH86rAAAA: Received packet MESSAGE data 0", "username": null, "path": null, "ip": null, "filename": "socket.py", "funcName": "receive", "levelname": "INFO", "lineno": 52, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.119581"}
{"message": "User tried to connect with expired token.", "username": null, "path": "/socket.io/", "ip": "127.0.0.1", "filename": "__init__.py", "funcName": "on_connect", "levelname": "INFO", "lineno": 24, "module": "__init__", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/hub_backend/routes/sockets/__init__.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.121462"}
{"message": "Disconnecting 1GrIqB7NdURHXyq3AAAB [/]", "username": null, "path": "/socket.io/", "ip": "127.0.0.1", "filename": "server.py", "funcName": "disconnect", "levelname": "INFO", "lineno": 565, "module": "server", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/socketio/server.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.121669"}
{"message": "5vuHkzT7GouFH86rAAAA: Sending packet MESSAGE data 1", "username": null, "path": "/socket.io/", "ip": "127.0.0.1", "filename": "socket.py", "funcName": "send", "levelname": "INFO", "lineno": 89, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.123379"}
{"message": "5vuHkzT7GouFH86rAAAA: Received request to upgrade to websocket", "username": null, "path": null, "ip": null, "filename": "socket.py", "funcName": "handle_get_request", "levelname": "INFO", "lineno": 101, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6234992640, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.123981"}
{"message": "5vuHkzT7GouFH86rAAAA: Sending packet MESSAGE data 0{\"sid\":\"1GrIqB7NdURHXyq3AAAB\"}", "username": null, "path": null, "ip": null, "filename": "socket.py", "funcName": "send", "levelname": "INFO", "lineno": 89, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6134034432, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.124908"}
{"message": "5vuHkzT7GouFH86rAAAA: Received packet CLOSE data ", "username": null, "path": null, "ip": null, "filename": "socket.py", "funcName": "receive", "levelname": "INFO", "lineno": 52, "module": "socket", "pathname": "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", "process": 21335, "thread": 6218166272, "hostname": "preprod.api.hub.datascientest.com", "service": "Hub Backend", "time": "2023-03-21T15:53:52.131554"}
5vuHkzT7GouFH86rAAAA: Received packet MESSAGE data 0
Disconnecting 1GrIqB7NdURHXyq3AAAB [/]
5vuHkzT7GouFH86rAAAA: Sending packet MESSAGE data 1
5vuHkzT7GouFH86rAAAA: Received request to upgrade to websocket
5vuHkzT7GouFH86rAAAA: Sending packet MESSAGE data 0{"sid":"1GrIqB7NdURHXyq3AAAB"}
5vuHkzT7GouFH86rAAAA: Received packet CLOSE data 
Traceback (most recent call last):
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/async_drivers/threading.py", line 36, in wait
    return self.ws.receive()
           ^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/simple_websocket/ws.py", line 112, in receive
    raise ConnectionClosed(self.close_reason, self.close_message)
simple_websocket.ws.ConnectionClosed: Connection closed: 1005 

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/sentry_sdk/integrations/flask.py", line 88, in sentry_patched_wsgi_app
    return SentryWsgiMiddleware(lambda *a, **kw: old_app(self, *a, **kw))(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/sentry_sdk/integrations/wsgi.py", line 140, in __call__
    reraise(*_capture_exception(hub))
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/sentry_sdk/_compat.py", line 54, in reraise
    raise value
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/sentry_sdk/integrations/wsgi.py", line 133, in __call__
    rv = self.app(
         ^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/sentry_sdk/integrations/flask.py", line 88, in <lambda>
    return SentryWsgiMiddleware(lambda *a, **kw: old_app(self, *a, **kw))(
                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/flask/app.py", line 2551, in __call__
    return self.wsgi_app(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/flask_socketio/__init__.py", line 43, in __call__
    return super(_SocketIOMiddleware, self).__call__(environ,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/middleware.py", line 63, in __call__
    return self.engineio_app.handle_request(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/socketio/server.py", line 607, in handle_request
    return self.eio.handle_request(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/server.py", line 410, in handle_request
    packets = socket.handle_get_request(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", line 103, in handle_get_request
    return getattr(self, '_upgrade_' + transport)(environ,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", line 158, in _upgrade_websocket
    return ws(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/async_drivers/threading.py", line 23, in __call__
    return self.app(self)
           ^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", line 190, in _websocket_handler
    pkt = websocket_wait()
          ^^^^^^^^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/socket.py", line 163, in websocket_wait
    data = ws.wait()
           ^^^^^^^^^
  File "/Users/seluj78/Projects/Datascientest/hub-backend/.venv/lib/python3.11/site-packages/engineio/async_drivers/threading.py", line 38, in wait
    raise IOError()
OSError

I cannot figure out where the error comes from and why I am getting a 1005 error and then a OSError. I thought it might be the fact that I send an send and an ack at the end, but these are after a return clause if one of the conditions fails.

Any thoughts on this ?

miguelgrinberg · 2023-03-21T16:17:15Z

miguelgrinberg
Mar 21, 2023
Maintainer

To reject a user in the connect handler you have to return False or raise ConnectionRefusedError. See the docs. At this early stage the connection is not fully established, so disconnecting isn't the right thing to do.

15 replies

Seluj78 Mar 21, 2023
Author

Thanks ! Also if you change the connection event to not return False but instead raise the ConnectionRefusedError, the client will still connect and not be disconnected as they should be.

miguelgrinberg Mar 21, 2023
Maintainer

Okay, I have fixed the ConnectionRefusedError problem. You can test the fix by installing Flask-SocketIO's main branch.

Still working on silencing that stack trace. In the mean time you can just ignore it.

miguelgrinberg Mar 21, 2023
Maintainer

Fix for the stack trace on disconnect or close is in the main branch of the python-engineio package. Could you install this branch and test this as well to confirm the fix?

Seluj78 Mar 22, 2023
Author

Thank you very much ! I will try this and tell you the results !

Seluj78 Mar 22, 2023
Author

It works like a charm ! I've pushed my changes on https://github.com/Seluj78/Flask-Socketio-bug-1958 (Mainly the requirements.txt).

When will you be able to release this on pypi ? :)

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