Websocket 返回状态 200 而不是 101 (flask socket.io)

Question

I've done quite a bit of reading around to try and solve this issue but I'm still stuck. My problem is with trying to get the websocket handshake to complete using socket.io client side and flask_socket.io server side.

I can run the flask development server on my local machine using:

 app = Flask(__name__) app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT' socketio = SocketIO(app) socketio.run(app) ...

and if I point chrome to localhost:5000 and press the button which I have linked to opening a websocket it works fine and chrome network tab shows status 101.

However on uploading the code to a remote machine and again using flask's development server but changing the port to 80,

 socketio.run(app,host='0.0.0.0',port=80)

the websocket handshake stops working and gives status 200 instead.

WebSocket connection to 'ws://example.com/socket.io/?EIO=3&transport=websocket&sid=cfb1949b243b42578fe422782a0db359' failed: Error during WebSocket handshake: Unexpected response code: 200

All websocket messages are now sent over xhr polling instead of inside the websocket frame.

I've followed all of the guides I can find on google relating to this but with no success. I was previously using nginx and gunicorn and followed the advice to change the nginx conf to allow upgrade to websockets but that didn't solve the problem. So I simplified to using the flask development server but I still haven't been able to get a successful handshake.

Answer 1

I found a solution after finding a similar problem posted here https://nolanlawson.com/2013/05/31/web-sockets-with-socket-io-node-js-and-nginx-port-80-considered-harmful/#comment-85425 .

It turns out many public wifi networks block websockets when they are running on port 80. However often ports 443 and 8080 are not blocked. You can find out which ports are blocked from this website: http://websocketstest.com/ . I just moved the address of my websocket from example.com to example.com:8080.

Answer 2

I ran into a similar problem but due to a different reason. When using flask-socketio you have to install gevent-websocket or else it's going to use long-polling and you'll see a lot of 200 responses. Thus, my solution to that problem was just.

pip install gevent-websocket