UPDATE: THIS IS CODE FOR AN OLD VERSION OF THE WEBSOCKET PROTOCOL HANDSHAKE AND IS NO LONGER VALID.
Yes, long hiatus. Hi.
WebSockets have amazing potential for browser-based gaming. Unfortunately, they are also in a constant state of flux, partially because the draft spec keeps changing and partially because browser makers want to minimize the amount of dickery that internet doofuses can inflict on you. Firefox and Opera have temporarily dropped WebSocket support but they should be back in again in Firefox 6.
The last few nights I've been trying to fix a handshake bug with my implementation of draft76 handshaking. This is the version currently used by Chrome and Safari. Finally got it working again after writing the following test case:
#!/usr/bin/env python
#------------------------------------------------------------------------------
# netboa/websocket/sanity_check.py
# Copyright 2011 Jim Storch
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain a
# copy of the License at http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
#------------------------------------------------------------------------------
"""
Wrote this to test that I'm correctly generating the responses for draft76
websockets.
"""
import struct
import hashlib
## From the draft76 docs:
REQUEST1 = (
'GET /demo HTTP/1.1\r\n'
'Host: example.com\r\n'
'Connection: Upgrade\r\n'
'Sec-WebSocket-Key2: 12998 5 Y3 1 .P00\r\n'
'Sec-WebSocket-Protocol: sample\r\n'
'Upgrade: WebSocket\r\n'
'Sec-WebSocket-Key1: 4 @1 46546xW%0l 1 5\r\n'
'Origin: http://example.com\r\n'
'\r\n'
'^n:ds[4U'
)
CORRECT_RESPONSE1 = "8jKS'y:G*Co,Wxa-"
REQUEST2 = (
'GET /demo HTTP/1.1\r\n'
'Host: example.com\r\n'
'Connection: Upgrade\r\n'
'Sec-WebSocket-Key2: 1_ tx7X d < nw 334J702) 7]o}` 0\r\n'
'Sec-WebSocket-Protocol: sample\r\n'
'Upgrade: WebSocket\r\n'
'Sec-WebSocket-Key1: 18x 6]8vM;54 *(5: { U1]8 z [ 8\r\n'
'Origin: http://example.com\r\n'
'\r\n'
'Tm[K T2u'
)
CORRECT_RESPONSE2 = 'fQJ,fN/4F4!~K~MH'
def parse_request(request):
req = {}
segments = request.split('\r\n\r\n', 1)
assert(len(segments) == 2)
header, payload = segments
lines = header.split('\r\n')
line = lines.pop(0)
items = line.split('\x20',2)
assert(len(items) == 3)
req['method'] = items[0]
req['request_uri'] = items[1]
req['http_version'] = items[2]
for line in lines:
parts = line.split(':\x20', 1)
assert(len(parts) == 2)
req[parts[0].lower()] = parts[1]
req['payload'] = payload
return req
def get_word(key):
digits=''
spaces=0
for char in key:
if char.isdigit():
digits += char
elif char == '\x20':
spaces += 1
assert(spaces)
assert(digits)
keynum = int(digits)
assert(keynum % spaces == 0)
wordval = keynum / spaces
assert(wordval < 2 ** 32)
return struct.pack("!I", wordval)
def create_token(req):
key1 = req.get('sec-websocket-key1', None)
assert(key1 is not None)
word1 = get_word(key1)
key2 = req.get('sec-websocket-key2', None)
assert(key2 is not None)
word2 = get_word(key2)
salt = req.get('payload', None)
assert(salt is not None)
assert(len(salt)==8)
return hashlib.md5(word1 + word2 + salt).digest()
req = parse_request(REQUEST1)
print create_token(req) == CORRECT_RESPONSE1
req = parse_request(REQUEST2)
print create_token(req) == CORRECT_RESPONSE2
Please note that this version is scheduled to be replaced by a draft called Hybi-08 which features a way simpler algorithm (which I *think* I have it nearly ready to drop in).
My interests are clearly taking Netboa towards being a browser-based game server. The combination of HTTP + WebSockets is quite appealing. It's really time to knuckle down and learn some Javascript -- or, more likely, lots of JQuery.
