Python WebSocket not working

Question

I tried to implement my first websocket example but I cannot make it work.

I use a python webserver:

import threading
import socket

def start_server():
    tick = 0
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind(('localhost', 1234))
    sock.listen(100)
    while True:
        print 'listening...'
        csock, address = sock.accept()
        tick+=1
        print 'connection!' 
        handshake(csock, tick)
        print 'handshaken'
        while True:
            interact(csock, tick)
            tick+=1


def send_data(client, str):
     #_write(request, '\x00' + message.encode('utf-8') + '\xff')
     str = '\x00' + str.encode('utf-8') + '\xff'
     return client.send(str)

def recv_data(client, count):
    data = client.recv(count)    
    return data.decode('utf-8', 'ignore')

def handshake(client, tick):
     our_handshake = "HTTP/1.1 101 Web Socket Protocol Handshake\r\n"+"Upgrade:         WebSocket\r\n"+"Connection: Upgrade\r\n"+"WebSocket-Origin: http://localhost:8888\r\n"+"WebSocket-Location: "+" ws://localhost:1234/websession\r\n\r\n"
     shake = recv_data(client, 255)
     print shake
     #We want to send this without any encoding
     client.send(our_handshake)

 def interact(client, tick):
     data = recv_data(client, 255)
     print 'got:%s' %(data)
     send_data(client, "clock ! tick%d" % (tick))
     send_data(client, "out ! %s" %(data))

 if __name__ == '__main__':
     start_server()

And HTML:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>Web Socket Example</title>
    <meta charset="UTF-8">
    <script>
      window.onload = function() {
        var s = new WebSocket("ws://localhost:1234/");
        s.onopen = function(e) { s.send('Ping'); }
        s.onmessage = function(e) { alert("got: " + e.data); }
        s.onclose = function(e) { alert("closed"); }
      };
    </script>
    </head>
    <body>
      <div id="holder" style="width:600px; height:300px"></div>
    </body>
 </html>

When I point my browser to http://localhost/websocket.html over apache2

I got the following error:

python websocketserver.py
listening...
connection!
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: localhost:1234
Origin: http://localhost
Sec-WebSocket-Key: A4sVkUhjVlTZbJrp2NUrqg==
Sec-WebSocket-Version: 13


handshaken
got:
Traceback (most recent call last):
  File "websocketserver.py", line 43, in <module>
    start_server()
  File "websocketserver.py", line 17, in start_server
    interact(csock, tick)
  File "websocketserver.py", line 40, in interact
    send_data(client, "out ! %s" %(data))
  File "websocketserver.py", line 24, in send_data
    return client.send(str)
socket.error: [Errno 32] Broken pipe

Can someone help me to fix this?

Thanks

My suggestion is that do not try to implement WebSocket stack yourself, but use a server and library which supports them out of the box. Some starting points duckduckgo.com/?q=!pypi+websocket — Mikko Ohtamaa
– Mikko Ohtamaa, Commented Jan 29, 2012 at 13:57

Community · Accepted Answer · 2021-10-07 05:59:28Z

3

You're responding with the older Hixie 75 protocol but the client only speaks the newer HyBi/IETF RFC 6455 WebSocket protocol.

Your response to the handshake should look more like this (the accept value is calculated from the key value from the client):

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

In HyBi/6455, the frames are no longer delimited with \x00 and \xff. Instead there is a header to every frame that contains several pieces of data including frame type and payload length.

See the spec for more information. Or better yet, you could refer and/or use an existing python WebSocket implementation such as pywebsocket, tornado, or my own project websockify which contains websocket.py which is a generic websocket server lib.

edited Oct 7, 2021 at 5:59

CommunityBot

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answered Jan 29, 2012 at 20:53

kanaka

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3 Comments

glarkou Over a year ago

Thanks mate. I will try to use websockify. I have already checked the VNC that you have built and I will take ideas from there in order to build my own implementation and satisfy my needs. I wanted to email you earlier but I couldn't send you an email through github.

glarkou Over a year ago

kanaka, where can I find a simple example of websockify with a python server sending images? And a final question. Is websockify working with the flash version of websockets for anyone not having an HTML5 enabled browser?

kanaka Over a year ago

I don't have a simple example of sending images, but if you send the raw data string using websockify and websock.js you'll get it as a binary string on the other end. Yes, websockify support [web-socket-js](htttp://github.com/kanaka/websockify) and include/websock.js will automatically load it if required.

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