#!/usr/bin/env python
'''
Python WebSocket library with support for "wss://" encryption.
Copyright 2011 Joel Martin
Licensed under LGPL version 3 (see docs/LICENSE.LGPL-3)
Supports following protocol versions:
- http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75
- http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76
- http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-10
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 os, sys, time, errno, signal, socket, traceback, select
import struct, array
from cgi import parse_qsl
from base64 import b64encode, b64decode
# Imports that vary by python version
if sys.hexversion > 0x3000000:
# python >= 3.0
from io import StringIO
from http.server import SimpleHTTPRequestHandler
from urllib.parse import urlsplit
b2s = lambda buf: buf.decode('latin_1')
s2b = lambda s: s.encode('latin_1')
s2a = lambda s: s
else:
# python 2.X
from cStringIO import StringIO
from SimpleHTTPServer import SimpleHTTPRequestHandler
from urlparse import urlsplit
# No-ops
b2s = lambda buf: buf
s2b = lambda s: s
s2a = lambda s: [ord(c) for c in s]
if sys.hexversion >= 0x2060000:
# python >= 2.6
from multiprocessing import Process
from hashlib import md5, sha1
else:
# python < 2.6
Process = None
from md5 import md5
from sha import sha as sha1
# Degraded functionality if these imports are missing
for mod, sup in [('numpy', 'HyBi protocol'),
('ssl', 'TLS/SSL/wss'), ('resource', 'daemonizing')]:
try:
globals()[mod] = __import__(mod)
except ImportError:
globals()[mod] = None
print("WARNING: no '%s' module, %s decode may be slower" % (
mod, sup))
class WebSocketServer(object):
"""
WebSockets server class.
Must be sub-classed with new_client method definition.
"""
buffer_size = 65536
server_handshake_hixie = """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
"""
server_handshake_hybi = """HTTP/1.1 101 Switching Protocols\r
Upgrade: websocket\r
Connection: Upgrade\r
Sec-WebSocket-Accept: %s\r
"""
GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
policy_response = """\n"""
class EClose(Exception):
pass
def __init__(self, listen_host='', listen_port=None, source_is_ipv6=False,
verbose=False, cert='', key='', ssl_only=None,
daemon=False, record='', web='',
run_once=False, timeout=0):
# settings
self.verbose = verbose
self.listen_host = listen_host
self.listen_port = listen_port
self.ssl_only = ssl_only
self.daemon = daemon
self.run_once = run_once
self.timeout = timeout
self.launch_time = time.time()
self.ws_connection = False
self.handler_id = 1
# Make paths settings absolute
self.cert = os.path.abspath(cert)
self.key = self.web = self.record = ''
if key:
self.key = os.path.abspath(key)
if web:
self.web = os.path.abspath(web)
if record:
self.record = os.path.abspath(record)
if self.web:
os.chdir(self.web)
# Sanity checks
if not ssl and self.ssl_only:
raise Exception("No 'ssl' module and SSL-only specified")
if self.daemon and not resource:
raise Exception("Module 'resource' required to daemonize")
# Show configuration
print("WebSocket server settings:")
print(" - Listen on %s:%s" % (
self.listen_host, self.listen_port))
print(" - Flash security policy server")
if self.web:
print(" - Web server. Web root: %s" % self.web)
if ssl:
if os.path.exists(self.cert):
print(" - SSL/TLS support")
if self.ssl_only:
print(" - Deny non-SSL/TLS connections")
else:
print(" - No SSL/TLS support (no cert file)")
else:
print(" - No SSL/TLS support (no 'ssl' module)")
if self.daemon:
print(" - Backgrounding (daemon)")
if self.record:
print(" - Recording to '%s.*'" % self.record)
#
# WebSocketServer static methods
#
@staticmethod
def socket(host, port=None, connect=False, prefer_ipv6=False):
""" Resolve a host (and optional port) to an IPv4 or IPv6
address. Create a socket. Bind to it if listen is set,
otherwise connect to it. Return the socket.
"""
flags = 0
if host == '':
host = None
if connect and not port:
raise Exception("Connect mode requires a port")
if not connect:
flags = flags | socket.AI_PASSIVE
addrs = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM,
socket.IPPROTO_TCP, flags)
if not addrs:
raise Exception("Could resolve host '%s'" % host)
addrs.sort(key=lambda x: x[0])
if prefer_ipv6:
addrs.reverse()
sock = socket.socket(addrs[0][0], addrs[0][1])
if connect:
sock.connect(addrs[0][4])
else:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(addrs[0][4])
sock.listen(100)
return sock
@staticmethod
def daemonize(keepfd=None, chdir='/'):
os.umask(0)
if chdir:
os.chdir(chdir)
else:
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)
except OSError:
_, exc, _ = sys.exc_info()
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())
@staticmethod
def unmask(buf, f):
pstart = f['hlen'] + 4
pend = pstart + f['length']
if numpy:
b = c = s2b('')
if f['length'] >= 4:
mask = numpy.frombuffer(buf, dtype=numpy.dtype('BB', b1, payload_len)
elif payload_len > 125 and payload_len < 65536:
header = struct.pack('>BBH', b1, 126, payload_len)
elif payload_len >= 65536:
header = struct.pack('>BBQ', b1, 127, payload_len)
#print("Encoded: %s" % repr(header + buf))
return header + buf, len(header), 0
@staticmethod
def decode_hybi(buf, base64=False):
""" Decode HyBi style WebSocket packets.
Returns:
{'fin' : 0_or_1,
'opcode' : number,
'mask' : 32_bit_number,
'hlen' : header_bytes_number,
'length' : payload_bytes_number,
'payload' : decoded_buffer,
'left' : bytes_left_number,
'close_code' : number,
'close_reason' : string}
"""
f = {'fin' : 0,
'opcode' : 0,
'mask' : 0,
'hlen' : 2,
'length' : 0,
'payload' : None,
'left' : 0,
'close_code' : None,
'close_reason' : None}
blen = len(buf)
f['left'] = blen
if blen < f['hlen']:
return f # Incomplete frame header
b1, b2 = struct.unpack_from(">BB", buf)
f['opcode'] = b1 & 0x0f
f['fin'] = (b1 & 0x80) >> 7
has_mask = (b2 & 0x80) >> 7
f['length'] = b2 & 0x7f
if f['length'] == 126:
f['hlen'] = 4
if blen < f['hlen']:
return f # Incomplete frame header
(f['length'],) = struct.unpack_from('>xxH', buf)
elif f['length'] == 127:
f['hlen'] = 10
if blen < f['hlen']:
return f # Incomplete frame header
(f['length'],) = struct.unpack_from('>xxQ', buf)
full_len = f['hlen'] + has_mask * 4 + f['length']
if blen < full_len: # Incomplete frame
return f # Incomplete frame header
# Number of bytes that are part of the next frame(s)
f['left'] = blen - full_len
# Process 1 frame
if has_mask:
# unmask payload
f['mask'] = buf[f['hlen']:f['hlen']+4]
f['payload'] = WebSocketServer.unmask(buf, f)
else:
print("Unmasked frame: %s" % repr(buf))
f['payload'] = buf[(f['hlen'] + has_mask * 4):full_len]
if base64 and f['opcode'] in [1, 2]:
try:
f['payload'] = b64decode(f['payload'])
except:
print("Exception while b64decoding buffer: %s" %
repr(buf))
raise
if f['opcode'] == 0x08:
if f['length'] >= 2:
f['close_code'] = struct.unpack_from(">H", f['payload'])
if f['length'] > 3:
f['close_reason'] = f['payload'][2:]
return f
@staticmethod
def encode_hixie(buf):
return s2b("\x00" + b2s(b64encode(buf)) + "\xff"), 1, 1
@staticmethod
def decode_hixie(buf):
end = buf.find(s2b('\xff'))
return {'payload': b64decode(buf[1:end]),
'hlen': 1,
'length': end - 1,
'left': len(buf) - (end + 1)}
@staticmethod
def gen_md5(keys):
""" Generate hash value for WebSockets hixie-76. """
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 b2s(md5(struct.pack('>II8s',
int(num1), int(num2), key3)).digest())
#
# WebSocketServer logging/output functions
#
def traffic(self, token="."):
""" Show traffic flow in verbose mode. """
if self.verbose and not self.daemon:
sys.stdout.write(token)
sys.stdout.flush()
def msg(self, msg):
""" Output message with handler_id prefix. """
if not self.daemon:
print("% 3d: %s" % (self.handler_id, msg))
def vmsg(self, msg):
""" Same as msg() but only if verbose. """
if self.verbose:
self.msg(msg)
#
# Main WebSocketServer methods
#
def send_frames(self, bufs=None):
""" Encode and send WebSocket frames. Any frames already
queued will be sent first. If buf is not set then only queued
frames will be sent. Returns the number of pending frames that
could not be fully sent. If returned pending frames is greater
than 0, then the caller should call again when the socket is
ready. """
tdelta = int(time.time()*1000) - self.start_time
if bufs:
for buf in bufs:
if self.version.startswith("hybi"):
if self.base64:
encbuf, lenhead, lentail = self.encode_hybi(
buf, opcode=1, base64=True)
else:
encbuf, lenhead, lentail = self.encode_hybi(
buf, opcode=2, base64=False)
else:
encbuf, lenhead, lentail = self.encode_hixie(buf)
if self.rec:
self.rec.write("%s,\n" %
repr("{%s{" % tdelta
+ encbuf[lenhead:-lentail]))
self.send_parts.append(encbuf)
while self.send_parts:
# Send pending frames
buf = self.send_parts.pop(0)
sent = self.client.send(buf)
if sent == len(buf):
self.traffic("<")
else:
self.traffic("<.")
self.send_parts.insert(0, buf[sent:])
break
return len(self.send_parts)
def recv_frames(self):
""" Receive and decode WebSocket frames.
Returns:
(bufs_list, closed_string)
"""
closed = False
bufs = []
tdelta = int(time.time()*1000) - self.start_time
buf = self.client.recv(self.buffer_size)
if len(buf) == 0:
closed = "Client closed abruptly"
return bufs, closed
if self.recv_part:
# Add partially received frames to current read buffer
buf = self.recv_part + buf
self.recv_part = None
while buf:
if self.version.startswith("hybi"):
frame = self.decode_hybi(buf, base64=self.base64)
#print("Received buf: %s, frame: %s" % (repr(buf), frame))
if frame['payload'] == None:
# Incomplete/partial frame
self.traffic("}.")
if frame['left'] > 0:
self.recv_part = buf[-frame['left']:]
break
else:
if frame['opcode'] == 0x8: # connection close
closed = "Client closed, reason: %s - %s" % (
frame['close_code'],
frame['close_reason'])
break
else:
if buf[0:2] == s2b('\xff\x00'):
closed = "Client sent orderly close frame"
break
elif buf[0:2] == s2b('\x00\xff'):
buf = buf[2:]
continue # No-op
elif buf.count(s2b('\xff')) == 0:
# Partial frame
self.traffic("}.")
self.recv_part = buf
break
frame = self.decode_hixie(buf)
self.traffic("}")
if self.rec:
start = frame['hlen']
end = frame['hlen'] + frame['length']
self.rec.write("%s,\n" %
repr("}%s}" % tdelta + buf[start:end]))
bufs.append(frame['payload'])
if frame['left']:
buf = buf[-frame['left']:]
else:
buf = ''
return bufs, closed
def send_close(self, code=None, reason=''):
""" Send a WebSocket orderly close frame. """
if self.version.startswith("hybi"):
msg = s2b('')
if code != None:
msg = struct.pack(">H%ds" % (len(reason)), code)
buf, h, t = self.encode_hybi(msg, opcode=0x08, base64=False)
self.client.send(buf)
elif self.version == "hixie-76":
buf = s2b('\xff\x00')
self.client.send(buf)
# No orderly close for 75
def do_handshake(self, sock, address):
"""
do_handshake does the following:
- Peek at the first few bytes from the socket.
- If the connection is Flash policy request then answer it,
close the socket and return.
- If the connection is an HTTPS/SSL/TLS connection then SSL
wrap the socket.
- Read from the (possibly wrapped) socket.
- If we have received a HTTP GET request and the webserver
functionality is enabled, answer it, close the socket and
return.
- Assume we have a WebSockets connection, parse the client
handshake data.
- Send a WebSockets handshake server response.
- Return the socket for this WebSocket client.
"""
stype = ""
ready = select.select([sock], [], [], 3)[0]
if not ready:
raise self.EClose("ignoring socket not ready")
# Peek, but do not read the data so that we have a opportunity
# to SSL wrap the socket first
handshake = sock.recv(1024, socket.MSG_PEEK)
#self.msg("Handshake [%s]" % handshake)
if handshake == "":
raise self.EClose("ignoring empty handshake")
elif handshake.startswith(s2b("")):
# Answer Flash policy request
handshake = sock.recv(1024)
sock.send(s2b(self.policy_response))
raise self.EClose("Sending flash policy response")
elif handshake[0] in ("\x16", "\x80"):
# SSL wrap the connection
if not ssl:
raise self.EClose("SSL connection but no 'ssl' module")
if not os.path.exists(self.cert):
raise self.EClose("SSL connection but '%s' not found"
% self.cert)
retsock = None
try:
retsock = ssl.wrap_socket(
sock,
server_side=True,
certfile=self.cert,
keyfile=self.key)
except ssl.SSLError:
_, x, _ = sys.exc_info()
if x.args[0] == ssl.SSL_ERROR_EOF:
raise self.EClose("")
else:
raise
scheme = "wss"
stype = "SSL/TLS (wss://)"
elif self.ssl_only:
raise self.EClose("non-SSL connection received but disallowed")
else:
retsock = sock
scheme = "ws"
stype = "Plain non-SSL (ws://)"
wsh = WSRequestHandler(retsock, address, not self.web)
if wsh.last_code == 101:
# Continue on to handle WebSocket upgrade
pass
elif wsh.last_code == 405:
raise self.EClose("Normal web request received but disallowed")
elif wsh.last_code < 200 or wsh.last_code >= 300:
raise self.EClose(wsh.last_message)
elif self.verbose:
raise self.EClose(wsh.last_message)
else:
raise self.EClose("")
h = self.headers = wsh.headers
path = self.path = wsh.path
prot = 'WebSocket-Protocol'
protocols = h.get('Sec-'+prot, h.get(prot, '')).split(',')
ver = h.get('Sec-WebSocket-Version')
if ver:
# HyBi/IETF version of the protocol
# HyBi-07 report version 7
# HyBi-08 - HyBi-12 report version 8
# HyBi-13 reports version 13
if ver in ['7', '8', '13']:
self.version = "hybi-%02d" % int(ver)
else:
raise self.EClose('Unsupported protocol version %s' % ver)
key = h['Sec-WebSocket-Key']
# Choose binary if client supports it
if 'binary' in protocols:
self.base64 = False
elif 'base64' in protocols:
self.base64 = True
else:
raise self.EClose("Client must support 'binary' or 'base64' protocol")
# Generate the hash value for the accept header
accept = b64encode(sha1(s2b(key + self.GUID)).digest())
response = self.server_handshake_hybi % b2s(accept)
if self.base64:
response += "Sec-WebSocket-Protocol: base64\r\n"
else:
response += "Sec-WebSocket-Protocol: binary\r\n"
response += "\r\n"
else:
# Hixie version of the protocol (75 or 76)
if h.get('key3'):
trailer = self.gen_md5(h)
pre = "Sec-"
self.version = "hixie-76"
else:
trailer = ""
pre = ""
self.version = "hixie-75"
# We only support base64 in Hixie era
self.base64 = True
response = self.server_handshake_hixie % (pre,
h['Origin'], pre, scheme, h['Host'], path)
if 'base64' in protocols:
response += "%sWebSocket-Protocol: base64\r\n" % pre
else:
self.msg("Warning: client does not report 'base64' protocol support")
response += "\r\n" + trailer
self.msg("%s: %s WebSocket connection" % (address[0], stype))
self.msg("%s: Version %s, base64: '%s'" % (address[0],
self.version, self.base64))
if self.path != '/':
self.msg("%s: Path: '%s'" % (address[0], self.path))
# Send server WebSockets handshake response
#self.msg("sending response [%s]" % response)
retsock.send(s2b(response))
# Return the WebSockets socket which may be SSL wrapped
return retsock
#
# Events that can/should be overridden in sub-classes
#
def started(self):
""" Called after WebSockets startup """
self.vmsg("WebSockets server started")
def poll(self):
""" Run periodically while waiting for connections. """
#self.vmsg("Running poll()")
pass
def fallback_SIGCHLD(self, sig, stack):
# Reap zombies when using os.fork() (python 2.4)
self.vmsg("Got SIGCHLD, reaping zombies")
try:
result = os.waitpid(-1, os.WNOHANG)
while result[0]:
self.vmsg("Reaped child process %s" % result[0])
result = os.waitpid(-1, os.WNOHANG)
except (OSError):
pass
def do_SIGINT(self, sig, stack):
self.msg("Got SIGINT, exiting")
sys.exit(0)
def top_new_client(self, startsock, address):
""" Do something with a WebSockets client connection. """
# Initialize per client settings
self.send_parts = []
self.recv_part = None
self.base64 = False
self.rec = None
self.start_time = int(time.time()*1000)
# handler process
try:
try:
self.client = self.do_handshake(startsock, address)
if self.record:
# Record raw frame data as JavaScript array
fname = "%s.%s" % (self.record,
self.handler_id)
self.msg("opening record file: %s" % fname)
self.rec = open(fname, 'w+')
self.rec.write("var VNC_frame_data = [\n")
self.ws_connection = True
self.new_client()
except self.EClose:
_, exc, _ = sys.exc_info()
# Connection was not a WebSockets connection
if exc.args[0]:
self.msg("%s: %s" % (address[0], exc.args[0]))
except Exception:
_, exc, _ = sys.exc_info()
self.msg("handler exception: %s" % str(exc))
if self.verbose:
self.msg(traceback.format_exc())
finally:
if self.rec:
self.rec.write("'EOF']\n")
self.rec.close()
if self.client and self.client != startsock:
self.client.close()
def new_client(self):
""" Do something with a WebSockets client connection. """
raise("WebSocketServer.new_client() must be overloaded")
def start_server(self):
"""
Daemonize if requested. Listen for for connections. Run
do_handshake() method for each connection. If the connection
is a WebSockets client then call new_client() method (which must
be overridden) for each new client connection.
"""
lsock = self.socket(self.listen_host, self.listen_port)
if self.daemon:
self.daemonize(keepfd=lsock.fileno(), chdir=self.web)
self.started() # Some things need to happen after daemonizing
# Allow override of SIGINT
signal.signal(signal.SIGINT, self.do_SIGINT)
if not Process:
# os.fork() (python 2.4) child reaper
signal.signal(signal.SIGCHLD, self.fallback_SIGCHLD)
while True:
try:
try:
self.client = None
startsock = None
pid = err = 0
time_elapsed = time.time() - self.launch_time
if self.timeout and time_elapsed > self.timeout:
self.msg('listener exit due to --timeout %s'
% self.timeout)
break
try:
self.poll()
ready = select.select([lsock], [], [], 1)[0]
if lsock in ready:
startsock, address = lsock.accept()
else:
continue
except Exception:
_, exc, _ = sys.exc_info()
if hasattr(exc, 'errno'):
err = exc.errno
elif hasattr(exc, 'args'):
err = exc.args[0]
else:
err = exc[0]
if err == errno.EINTR:
self.vmsg("Ignoring interrupted syscall")
continue
else:
raise
if self.run_once:
# Run in same process if run_once
self.top_new_client(startsock, address)
if self.ws_connection :
self.msg('%s: exiting due to --run-once'
% address[0])
break
elif Process:
self.vmsg('%s: new handler Process' % address[0])
p = Process(target=self.top_new_client,
args=(startsock, address))
p.start()
# child will not return
else:
# python 2.4
self.vmsg('%s: forking handler' % address[0])
pid = os.fork()
if pid == 0:
# child handler process
self.top_new_client(startsock, address)
break # child process exits
# parent process
self.handler_id += 1
except KeyboardInterrupt:
_, exc, _ = sys.exc_info()
print("In KeyboardInterrupt")
pass
except SystemExit:
_, exc, _ = sys.exc_info()
print("In SystemExit")
break
except Exception:
_, exc, _ = sys.exc_info()
self.msg("handler exception: %s" % str(exc))
if self.verbose:
self.msg(traceback.format_exc())
finally:
if startsock:
startsock.close()
# HTTP handler with WebSocket upgrade support
class WSRequestHandler(SimpleHTTPRequestHandler):
def __init__(self, req, addr, only_upgrade=False):
self.only_upgrade = only_upgrade # only allow upgrades
SimpleHTTPRequestHandler.__init__(self, req, addr, object())
def do_GET(self):
if (self.headers.get('upgrade') and
self.headers.get('upgrade').lower() == 'websocket'):
if (self.headers.get('sec-websocket-key1') or
self.headers.get('websocket-key1')):
# For Hixie-76 read out the key hash
self.headers.__setitem__('key3', self.rfile.read(8))
# Just indicate that an WebSocket upgrade is needed
self.last_code = 101
self.last_message = "101 Switching Protocols"
elif self.only_upgrade:
# Normal web request responses are disabled
self.last_code = 405
self.last_message = "405 Method Not Allowed"
else:
SimpleHTTPRequestHandler.do_GET(self)
def send_response(self, code, message=None):
# Save the status code
self.last_code = code
SimpleHTTPRequestHandler.send_response(self, code, message)
def log_message(self, f, *args):
# Save instead of printing
self.last_message = f % args