#!/usr/bin/python
'''
Python WebSocket library with support for "wss://" encryption.
Copyright 2010 Joel Martin
Licensed under LGPL version 3 (see docs/LICENSE.LGPL-3)
You can make a cert/key with openssl using:
openssl req -new -x509 -days 365 -nodes -out self.pem -keyout self.pem
as taken from http://docs.python.org/dev/library/ssl.html#certificates
'''
import sys, socket, ssl, struct, traceback
import os, resource, errno, signal # daemonizing
from base64 import b64encode, b64decode
try:
from hashlib import md5
except:
from md5 import md5 # Support python 2.4
from urlparse import urlsplit
from cgi import parse_qsl
settings = {
'verbose' : False,
'listen_host' : '',
'listen_port' : None,
'handler' : None,
'handler_id' : 1,
'cert' : None,
'ssl_only' : False,
'daemon' : True,
'record' : None, }
server_handshake = """HTTP/1.1 101 Web Socket Protocol Handshake\r
Upgrade: WebSocket\r
Connection: Upgrade\r
%sWebSocket-Origin: %s\r
%sWebSocket-Location: %s://%s%s\r
%sWebSocket-Protocol: sample\r
\r
%s"""
policy_response = """<cross-domain-policy><allow-access-from domain="*" to-ports="*" /></cross-domain-policy>\n"""
class EClose(Exception):
pass
def traffic(token="."):
if settings['verbose'] and not settings['daemon']:
sys.stdout.write(token)
sys.stdout.flush()
def handler_msg(msg):
if not settings['daemon']:
print " %d: %s" % (settings['handler_id'], msg)
def encode(buf):
buf = b64encode(buf)
return "\x00%s\xff" % buf
def decode(buf):
""" Parse out WebSocket packets. """
if buf.count('\xff') > 1:
return [b64decode(d[1:]) for d in buf.split('\xff')]
else:
return [b64decode(buf[1:-1])]
def parse_handshake(handshake):
ret = {}
req_lines = handshake.split("\r\n")
if not req_lines[0].startswith("GET "):
raise Exception("Invalid handshake: no GET request line")
ret['path'] = req_lines[0].split(" ")[1]
for line in req_lines[1:]:
if line == "": break
var, val = line.split(": ")
ret[var] = val
if req_lines[-2] == "":
ret['key3'] = req_lines[-1]
return ret
def gen_md5(keys):
key1 = keys['Sec-WebSocket-Key1']
key2 = keys['Sec-WebSocket-Key2']
key3 = keys['key3']
spaces1 = key1.count(" ")
spaces2 = key2.count(" ")
num1 = int("".join([c for c in key1 if c.isdigit()])) / spaces1
num2 = int("".join([c for c in key2 if c.isdigit()])) / spaces2
return md5(struct.pack('>II8s', num1, num2, key3)).digest()
def do_handshake(sock):
# Peek, but don't read the data
handshake = sock.recv(1024, socket.MSG_PEEK)
#handler_msg("Handshake [%s]" % repr(handshake))
if handshake == "":
handler_msg("ignoring empty handshake")
sock.close()
return False
elif handshake.startswith("<policy-file-request/>"):
handshake = sock.recv(1024)
handler_msg("Sending flash policy response")
sock.send(policy_response)
sock.close()
return False
elif handshake[0] in ("\x16", "\x80"):
retsock = ssl.wrap_socket(
sock,
server_side=True,
certfile=settings['cert'])
scheme = "wss"
handler_msg("using SSL/TLS")
elif settings['ssl_only']:
handler_msg("non-SSL connection disallowed")
sock.close()
return False
else:
retsock = sock
scheme = "ws"
handler_msg("using plain (not SSL) socket")
handshake = retsock.recv(4096)
#handler_msg("handshake: " + repr(handshake))
if len(handshake) == 0:
raise EClose("Client closed during handshake")
h = parse_handshake(handshake)
if h.get('key3'):
trailer = gen_md5(h)
pre = "Sec-"
handler_msg("using protocol version 76")
else:
trailer = ""
pre = ""
handler_msg("using protocol version 75")
response = server_handshake % (pre, h['Origin'], pre, scheme,
h['Host'], h['path'], pre, trailer)
#handler_msg("sending response:", repr(response))
retsock.send(response)
return retsock
def daemonize(keepfd=None):
os.umask(0)
os.chdir('/')
os.setgid(os.getgid()) # relinquish elevations
os.setuid(os.getuid()) # relinquish elevations
# Double fork to daemonize
if os.fork() > 0: os._exit(0) # Parent exits
os.setsid() # Obtain new process group
if os.fork() > 0: os._exit(0) # Parent exits
# Signal handling
def terminate(a,b): os._exit(0)
signal.signal(signal.SIGTERM, terminate)
signal.signal(signal.SIGINT, signal.SIG_IGN)
# Close open files
maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
if maxfd == resource.RLIM_INFINITY: maxfd = 256
for fd in reversed(range(maxfd)):
try:
if fd != keepfd:
os.close(fd)
elif settings['verbose']:
print "Keeping fd: %d" % fd
except OSError, exc:
if exc.errno != errno.EBADF: raise
# Redirect I/O to /dev/null
os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdin.fileno())
os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdout.fileno())
os.dup2(os.open(os.devnull, os.O_RDWR), sys.stderr.fileno())
def start_server():
lsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
lsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
lsock.bind((settings['listen_host'], settings['listen_port']))
lsock.listen(100)
if settings['daemon']:
daemonize(keepfd=lsock.fileno())
# Reep zombies
signal.signal(signal.SIGCHLD, signal.SIG_IGN)
print 'Waiting for connections on %s:%s' % (
settings['listen_host'], settings['listen_port'])
while True:
try:
csock = startsock = None
pid = 0
startsock, address = lsock.accept()
handler_msg('got client connection from %s' % address[0])
handler_msg("forking handler process")
pid = os.fork()
if pid == 0: # handler process
csock = do_handshake(startsock)
if not csock:
handler_msg("No connection after handshake");
break
settings['handler'](csock)
else: # parent process
settings['handler_id'] += 1
except EClose, exc:
handler_msg("handler exit: %s" % exc.args)
except Exception, exc:
handler_msg("handler exception: %s" % str(exc))
#handler_msg(traceback.format_exc())
if pid == 0:
if csock: csock.close()
if startsock and startsock != csock: startsock.close()
break # Child process exits