A simple WebSockets server with no dependencies

websocketserver.py

import struct
import SocketServer
from base64 import b64encode
from hashlib import sha1
from mimetools import Message
from StringIO import StringIO

class WebSocketsHandler(SocketServer.StreamRequestHandler):
    magic = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'

    def setup(self):
        SocketServer.StreamRequestHandler.setup(self)
        print "connection established", self.client_address
        self.handshake_done = False

    def handle(self):
        while True:
            if not self.handshake_done:
                self.handshake()
            else:
                self.read_next_message()

    def read_next_message(self):
        length = ord(self.rfile.read(2)[1]) & 127
        if length == 126:
            length = struct.unpack(">H", self.rfile.read(2))[0]
        elif length == 127:
            length = struct.unpack(">Q", self.rfile.read(8))[0]
        masks = [ord(byte) for byte in self.rfile.read(4)]
        decoded = ""
        for char in self.rfile.read(length):
            decoded += chr(ord(char) ^ masks[len(decoded) % 4])
        self.on_message(decoded)

    def send_message(self, message):
        self.request.send(chr(129))
        length = len(message)
        if length <= 125:
            self.request.send(chr(length))
        elif length >= 126 and length <= 65535:
            self.request.send(126)
            self.request.send(struct.pack(">H", length))
        else:
            self.request.send(127)
            self.request.send(struct.pack(">Q", length))
        self.request.send(message)

    def handshake(self):
        data = self.request.recv(1024).strip()
        headers = Message(StringIO(data.split('\r\n', 1)[1]))
        if headers.get("Upgrade", None) != "websocket":
            return
        print 'Handshaking...'
        key = headers['Sec-WebSocket-Key']
        digest = b64encode(sha1(key + self.magic).hexdigest().decode('hex'))
        response = 'HTTP/1.1 101 Switching Protocols\r\n'
        response += 'Upgrade: websocket\r\n'
        response += 'Connection: Upgrade\r\n'
        response += 'Sec-WebSocket-Accept: %s\r\n\r\n' % digest
        self.handshake_done = self.request.send(response)

    def on_message(self, message):
        print messsage

if __name__ == "__main__":
    server = SocketServer.TCPServer(
        ("localhost", 9999), WebSocketsHandler)
    server.serve_forever()

Try it out with something like this (http://jsfiddle.net/ is handy for quick tests...):

var ws = new WebSocket("ws://localhost:9999/");
ws.onopen = function() {
    function schedule(i) {
        setTimeout(function() { 
          ws.send('Hello from the client! (iteration ' + i + ')');
          schedule(i + 1);
        }, 1000);            
    };
    schedule(1);            
};

I'm working on something using this as the websocket backend and the Webkit notification API :D
https://github.com/Mause/websocket-notifications/

You have a typo in your on_message method; you've got the letter S three times on line 63

def on_message(self, message):
print messsage # typo

You should change the serve_forever() part to something like this:
try:
server.serve_forever()
except KeyboardInterrupt:
print "Got ^C"
server.server_close();
print "bye!"

Awesome, thanks for sharing!

I am facing a weird problem. Only one client can be connected to this server. Am I missing something really basic ?

@Applterate Check this for multiple client support.

Very impressive. I am happy to be a witness to the excellence of this code.

im trying to use this with python3.. struggling with mimetools.Message can somebody give me a hint how to replace correct with the email package?

I'm totally noob with python and need to make something fast so pelase can you help me. How can i create instance of this class and use send_message() method from external file ?

self.request.send(126) should be self.request.send(chr(126)), same for 127.

You have a typo on line 63:

  def on_message(self, message):
-     print messsage
+     print message

Thanks for this nice example, which inspired (as in reuse some code) to make a combined HTTP/WebSocket server using one and the same port. The HTTP server part is based on the standard SimpleHTTPServer library.

See https://gist.github.com/SevenW/47be2f9ab74cac26bf21
and for more background:
http://www.sevenwatt.com/main/websocket-html-webserver-python/ for some background

Thank you @jkp that was very helpful. I've taken it one step further than @SevenW and turned it in to an git repository (https://github.com/mbirtwell/simple-websockets). I've got examples there of getting this to work with SimpleHTTPServer, wsgiref and werkzeug.

I have added support for SSL/HTTPS, and added exception handling. I updated my gist,
https://gist.github.com/SevenW/47be2f9ab74cac26bf21
and also created a repository for further maintenance:
https://github.com/SevenW/httpwebsockethandler

An elaborate example for the web interface for Plugwise-2-py can be found here:
https://github.com/SevenW/Plugwise-2-py

Thanks @jkp, that's lightweight and serves most development purposes. I recommend adding

SocketServer.TCPServer.allow_reuse_address = True

to set SO_REUSEADDR socket option before TCPServer instantiation on line 66 in case the script is run repeatedly during development.

Here is a somewhat more modular version if anyone wants to use this as an import.

Hi, I trying launch the web socket server with param secure and I get this error:

File "main.py", line 50, in _ws_main
    server.socket = ssl.wrap_socket (server.socket, certfile='./server.pem', server_side=True)
File "/usr/lib/python2.7/ssl.py", line 891, in wrap_socket
    ciphers=ciphers)
File "/usr/lib/python2.7/ssl.py", line 509, in __init__
    self._context.load_cert_chain(certfile, keyfile)
ssl.SSLError: [SSL] PEM lib (_ssl.c:2525)

I read that this error is caused for a bad private key, but I've added it as a parameter in the function wrap_socket() and result is the same. My cert and key are self-signed, I created it with openssl command.
How I can resolve this?

Thanks in advance

i need to send binary data over this server. will it work ?

I am facing a weird problem. Only one client can be connected to this server. Am I missing something really basic ?

To handle multiple client support:

At the beginning of the websocketserver-py file: I added:
import sys ###
import threading ###
from SocketServer import ThreadingMixIn ###

At the end of the websocketserver-py file: I added a class ThreadedWebSocketServer and adapted the 'if name == "main" ' part.

class ThreadedWebSocketServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
"""Handle requests in a separate thread."""
# Ctrl-C will cleanly kill all spawned threads
daemon_threads = True
# much faster rebinding
allow_reuse_address = True

def __init__(self, server_address, RequestHandlerClass):
    SocketServer.TCPServer.__init__(self, server_address, RequestHandlerClass)

if name == "main":
##server = SocketServer.TCPServer(
## ("127.0.0.1", 8088), WebSocketsHandler)
server = ThreadedWebSocketServer(("127.0.0.1", 8088), WebSocketsHandler) ###
# terminate with Ctrl-C
try:
server.serve_forever()
except KeyboardInterrupt:
print ('========================================')
print ('^C received, shutting down server')
print ('========================================')
server.socket.close()
sys.exit(0)