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I'm using python to implement a simple websocket server. The handshake I'm using comes from http://en.wikipedia.org/w/index.php?title=WebSockets&oldid=372387414.
The handshake itself seems to work, but when I hit send, I get a javascript error:
Uncaught Error: INVALID_STATE_ERR: DOM Exception 11
Here's the html:
<!doctype html>
<html>
<head>
<title>ws_json</title>
</head>
<body onload="handleLoad();" onunload="handleUnload();">
<input type="text" id='input' />
<input type="button" value="submit" onclick="handleSubmit()" />
<div id="display"></div>
<script type="text/javascript">
function showmsg(str){
display = document.getElementById("display");
display.innerHTML += "<p>" + str + "</p>";
}
function send(str){
ws.send(str.length);
ws.send(str);
}
function handleSubmit(){
input = document.getElementById('input');
send(input.value);
input.focus();
input.value = '';
}
function handleLoad(){
ws = new WebSocket("ws://localhost:8888/");
ws.onopen = function(){
showmsg("websocket opened.");
}
ws.onclose = function(){
showmsg("websocket closed.");
}
}
function handleUnload(){
ws.close();
}
</script>
</body>
</html>
And here's the python code:
import socket
import threading
import json
PORT = 8888
LOCATION = "localhost:8888"
def handler(s):
print " in handler "
ip, _ = s.getpeername()
print "New connection from %s" % ip
request = s.recv(1024)
print "\n%s\n" % request
print s.getpeername()
# send response
response = "HTTP/1.1 101 Web Socket Protocol Handshake\r\n"
response += "Upgrade: WebSocket\r\n"
response += "Connection: Upgrade\r\n"
try:
peername = s.getpeername()
response += "Sec-WebSocket-Origin: http://%s\r\n" % peername[0] # % request[request.index("Origin: ")+8:-4]
except ValueError:
print "Bad Request"
raise socket.error
response += "Sec-WebSocket-Location: ws://%s\r\n" % LOCATION
response += "Sec-WebSocket-Protocol: sample"
response = response.strip() + "\r\n\r\n"
print response
s.send(response)
while True:
length = s.recv(1)
print length
if not length:
break
length = int(length)
print "Length: %i" % length
data = s.recv(length)
print "Received: %s" % data
print ""
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(('localhost', PORT))
s.listen(5)
print "server is running..."
while True:
sock, addr = s.accept()
threading.Thread(target=handler, args=(sock, )).start()
Does anyone know what I'm doing wrong here?
926
I tested your code on Firefox 4 and got the same error upon hitting send, however before that I got
Firefox can't establish a connection to the server at ws://localhost:8888/.
which is probably why the WebSocket object was destroyed. I suspect your handshake response is missing something, so Firefox is closing the socket.
From the Wikipedia article on Websockets:
The Sec-WebSocket-Key1 and Sec-WebSocket-Key2 fields and the eight bytes after the fields are random tokens which the server uses to construct a 16 byte token at the end of its handshake to prove that it has read the client's handshake.
Your server's response does not have this special number at the bottom, So I think we need to figure out how to generate it, and include it.
EDIT: How to generate that number
Lets start with key1, key2, and the 8 bytes at the end of the handshake
key1 = "18x 6]8vM;54 *(5: { U1]8 z [ 8"
key2 = "1_ tx7X d < nw 334J702) 7]o}` 0"
end8 = "Tm[K T2u"
We make a number for each key by ignoring every character that is not a digit 0-9. In Python:
def numFromKey(key):
return int(filter(lambda c: c in map(str,range(10)),key))
next we divide that number by the number of spaces in the original key string, so here is a is a function that counts the spaces in a string.
def spacesIn(key):
return len(filter(lambda c: c==' ',key))
The two numbers resulting from the keys are:
pkey1 = numFromKey(key1)/spacesIn(key1)
pkey2 = numFromKey(key2)/spacesIn(key2)
Now we need to concatenate the bytes of pkey1, pkey2, and end8. The processed keys need to be represented as 32 bit Big-Endian numbers.
from struct import pack
catstring = pack('>L',pkey1) + pack('>L',pkey2) + end8
Then we take the md5 hash of those bytes to get the magic number that we tack on the end of the handshake
import md5
magic = md5.new(catstring).digest()
Thats how I think it works at least
198
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