I have a flask socket io application that used to work a few months ago, but I'm not sure whats happened. I've stripped it down to the basics. The output logs show a bunch of garbled nonsense that I think is supposed to be the start of a TLS handshake (from the research I've done). Console is showing a CORS related error. I don't know why that is - shouldn't the origin be the same for local host? Is the server sending secure requests?
I've tried socketio = SocketIO(app, cors_allowed_origins='*')
as mentioned in this question, but the issue is still there.
This is the logging output, in the past it would show the polling url:
My application.py code:
from flask import Flask, render_template
from flask_socketio import SocketIO, emit
app = Flask(__name__)
app.config["SECRET_KEY"] = 'secret?'
socketio = SocketIO(app, engineio_logger=True, logger=True)
@app.route("/", methods=["GET"])
def index():
return render_template("layout.html")
@socketio.on('message')
def handleMessage(msg):
print(msg)
emit(msg, broadcast=True)
if __name__ == '__main__':
socketio.run(app)
Javascript:
document.addEventListener('DOMContentLoaded', () => {
connectSocketIO();
addMessage();
});
var socket;
function connectSocketIO () {
socket = io.connect('http://' + document.domain + ':' + location.port);
socket.on('connect', () => {
console.log('client connected');
socket.on('disconnect', () => console.log('client disconnected'));
});
socket.on('message', (data) => {
console.log(data);
});
}
function addMessage () {
// emit a new message announcement when message is posted
document.querySelector('#btn').onclick = () => {
const message = document.querySelector('input').value;
socket.emit('message', {'message': message});
return false;
};
}
requirements.txt
Flask
Flask-SocketIO
gunicorn
eventlet==0.24.1
Edit:
It appears the initial issue was caused by specifying https protocol in io.connect - changing that has solved the garbled output.
This has caused Firefox to throw an error:
Firefox can't establish a connection to the server as wss://url
In Chrome it works, but the connection changes to http.
Both warn about cookies misusing the sameSite attribute
Cookie "io" will be soon rejected because it has the "sameSite" attribute set to "none" or an invalid value, without the "secure" attribute.
Heroku Procfile:
web: gunicorn --worker-class eventlet -w 1 application:app
On the server side, the logs for Heroku:
2020-07-28T12:41:43.350016+00:00 app[web.1]: https://flack-messaging-app.herokuapp.com is not an accepted origin.
2020-07-28T12:41:43.346991+00:00 heroku[router]: at=info method=POST path="/socket.io/?EIO=3&transport=polling&t=NELSMDM&sid=f25e5af236d347eaa3100951014be579" host=flack-messaging-app.herokuapp.com request_id=1041f8b4-71b8-4cf5-a321-75014d2ccde7 fwd="78.146.97.151" dyno=web.1 connect=1ms service=8ms status=400 bytes=182 protocol=https
2020-07-28T12:41:44.399195+00:00 heroku[router]: at=info method=POST path="/socket.io/?EIO=3&transport=polling&t=NELSMTk&sid=f25e5af236d347eaa3100951014be579" host=flack-messaging-app.herokuapp.com request_id=dba0c5f4-6afd-4621-ad7e-4c511911a714 fwd="78.146.97.151" dyno=web.1 connect=2ms service=3ms status=400 bytes=182 protocol=https
2020-07-28T12:41:44.402016+00:00 app[web.1]: https://flack-messaging-app.herokuapp.com is not an accepted origin.
2020-07-28T12:41:45.481764+00:00 heroku[router]: at=info method=GET path="/socket.io/?EIO=3&transport=polling&t=NELSMkn" host=flack-messaging-app.herokuapp.com request_id=8ba7cc91-5e33-4113-a15d-84e5ceba8ca4 fwd="78.146.97.151" dyno=web.1 connect=1ms service=3ms status=200 bytes=385 protocol=https
2020-07-28T12:41:45.483979+00:00 app[web.1]: 5b1138c7e62a4ea2bff2beb55eb5241d: Sending packet OPEN data {'sid': '5b1138c7e62a4ea2bff2beb55eb5241d', 'upgrades': ['websocket'], 'pingTimeout': 60000, 'pingInterval': 25000}
2020-07-28T12:41:45.484100+00:00 app[web.1]: 5b1138c7e62a4ea2bff2beb55eb5241d: Sending packet MESSAGE data 0
2020-07-28T12:41:45.571836+00:00 app[web.1]: https://flack-messaging-app.herokuapp.com is not an accepted origin.
2020-07-28T12:41:45.566552+00:00 heroku[router]: at=info method=GET path="/socket.io/?EIO=3&transport=websocket&sid=5b1138c7e62a4ea2bff2beb55eb5241d" host=flack-messaging-app.herokuapp.com request_id=d802cd1c-c875-4406-a75e-2c3ca2368de0 fwd="78.146.97.151" dyno=web.1 connect=0ms service=2ms status=400 bytes=187 protocol=https
2020-07-28T12:41:48.383640+00:00 heroku[router]: at=error code=H12 desc="Request timeout" method=GET path="/socket.io/?EIO=3&transport=polling&t=NELSG6k&sid=f25e5af236d347eaa3100951014be579" host=flack-messaging-app.herokuapp.com request_id=26757146-e11f-43d6-a243-65172f72dd5e fwd="78.146.97.151" dyno=web.1 connect=1ms service=30001ms status=503 bytes=0 protocol=https
