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215ae8e564
Call waitpid in loop to catch SIGCHLD signals that happen while handling the original SIGCHLD signal. Pulled from websockify.
446 lines
14 KiB
Python
Executable File
446 lines
14 KiB
Python
Executable File
#!/usr/bin/python
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'''
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Python WebSocket library with support for "wss://" encryption.
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Copyright 2010 Joel Martin
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Licensed under LGPL version 3 (see docs/LICENSE.LGPL-3)
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You can make a cert/key with openssl using:
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openssl req -new -x509 -days 365 -nodes -out self.pem -keyout self.pem
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as taken from http://docs.python.org/dev/library/ssl.html#certificates
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'''
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import sys, socket, ssl, struct, traceback, select
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import os, resource, errno, signal # daemonizing
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from SimpleHTTPServer import SimpleHTTPRequestHandler
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from cStringIO import StringIO
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from base64 import b64encode, b64decode
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try:
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from hashlib import md5
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except:
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from md5 import md5 # Support python 2.4
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from urlparse import urlsplit
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from cgi import parse_qsl
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class WebSocketServer(object):
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"""
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WebSockets server class.
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Must be sub-classed with new_client method definition.
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"""
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server_handshake = """HTTP/1.1 101 Web Socket Protocol Handshake\r
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Upgrade: WebSocket\r
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Connection: Upgrade\r
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%sWebSocket-Origin: %s\r
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%sWebSocket-Location: %s://%s%s\r
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%sWebSocket-Protocol: sample\r
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\r
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%s"""
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policy_response = """<cross-domain-policy><allow-access-from domain="*" to-ports="*" /></cross-domain-policy>\n"""
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class EClose(Exception):
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pass
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def __init__(self, listen_host='', listen_port=None,
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verbose=False, cert='', key='', ssl_only=None,
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daemon=False, record='', web=''):
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# settings
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self.verbose = verbose
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self.listen_host = listen_host
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self.listen_port = listen_port
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self.ssl_only = ssl_only
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self.daemon = daemon
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# Make paths settings absolute
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self.cert = os.path.abspath(cert)
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self.key = self.web = self.record = ''
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if key:
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self.key = os.path.abspath(key)
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if web:
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self.web = os.path.abspath(web)
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if record:
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self.record = os.path.abspath(record)
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if self.web:
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os.chdir(self.web)
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self.handler_id = 1
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print "WebSocket server settings:"
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print " - Listen on %s:%s" % (
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self.listen_host, self.listen_port)
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print " - Flash security policy server"
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if self.web:
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print " - Web server"
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if os.path.exists(self.cert):
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print " - SSL/TLS support"
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if self.ssl_only:
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print " - Deny non-SSL/TLS connections"
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else:
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print " - No SSL/TLS support (no cert file)"
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if self.daemon:
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print " - Backgrounding (daemon)"
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#
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# WebSocketServer static methods
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#
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@staticmethod
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def daemonize(self, keepfd=None):
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os.umask(0)
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if self.web:
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os.chdir(self.web)
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else:
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os.chdir('/')
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os.setgid(os.getgid()) # relinquish elevations
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os.setuid(os.getuid()) # relinquish elevations
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# Double fork to daemonize
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if os.fork() > 0: os._exit(0) # Parent exits
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os.setsid() # Obtain new process group
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if os.fork() > 0: os._exit(0) # Parent exits
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# Signal handling
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def terminate(a,b): os._exit(0)
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signal.signal(signal.SIGTERM, terminate)
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signal.signal(signal.SIGINT, signal.SIG_IGN)
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# Close open files
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maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
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if maxfd == resource.RLIM_INFINITY: maxfd = 256
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for fd in reversed(range(maxfd)):
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try:
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if fd != keepfd:
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os.close(fd)
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except OSError, exc:
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if exc.errno != errno.EBADF: raise
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# Redirect I/O to /dev/null
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os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdin.fileno())
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os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdout.fileno())
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os.dup2(os.open(os.devnull, os.O_RDWR), sys.stderr.fileno())
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@staticmethod
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def encode(buf):
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""" Encode a WebSocket packet. """
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buf = b64encode(buf)
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return "\x00%s\xff" % buf
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@staticmethod
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def decode(buf):
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""" Decode WebSocket packets. """
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if buf.count('\xff') > 1:
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return [b64decode(d[1:]) for d in buf.split('\xff')]
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else:
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return [b64decode(buf[1:-1])]
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@staticmethod
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def parse_handshake(handshake):
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""" Parse fields from client WebSockets handshake. """
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ret = {}
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req_lines = handshake.split("\r\n")
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if not req_lines[0].startswith("GET "):
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raise Exception("Invalid handshake: no GET request line")
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ret['path'] = req_lines[0].split(" ")[1]
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for line in req_lines[1:]:
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if line == "": break
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try:
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var, val = line.split(": ")
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except:
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raise Exception("Invalid handshake header: %s" % line)
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ret[var] = val
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if req_lines[-2] == "":
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ret['key3'] = req_lines[-1]
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return ret
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@staticmethod
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def gen_md5(keys):
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""" Generate hash value for WebSockets handshake v76. """
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key1 = keys['Sec-WebSocket-Key1']
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key2 = keys['Sec-WebSocket-Key2']
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key3 = keys['key3']
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spaces1 = key1.count(" ")
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spaces2 = key2.count(" ")
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num1 = int("".join([c for c in key1 if c.isdigit()])) / spaces1
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num2 = int("".join([c for c in key2 if c.isdigit()])) / spaces2
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return md5(struct.pack('>II8s', num1, num2, key3)).digest()
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#
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# WebSocketServer logging/output functions
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#
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def traffic(self, token="."):
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""" Show traffic flow in verbose mode. """
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if self.verbose and not self.daemon:
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sys.stdout.write(token)
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sys.stdout.flush()
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def msg(self, msg):
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""" Output message with handler_id prefix. """
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if not self.daemon:
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print "% 3d: %s" % (self.handler_id, msg)
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def vmsg(self, msg):
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""" Same as msg() but only if verbose. """
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if self.verbose:
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self.msg(msg)
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#
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# Main WebSocketServer methods
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#
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def do_handshake(self, sock, address):
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"""
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do_handshake does the following:
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- Peek at the first few bytes from the socket.
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- If the connection is Flash policy request then answer it,
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close the socket and return.
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- If the connection is an HTTPS/SSL/TLS connection then SSL
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wrap the socket.
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- Read from the (possibly wrapped) socket.
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- If we have received a HTTP GET request and the webserver
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functionality is enabled, answer it, close the socket and
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return.
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- Assume we have a WebSockets connection, parse the client
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handshake data.
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- Send a WebSockets handshake server response.
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- Return the socket for this WebSocket client.
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"""
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stype = ""
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ready = select.select([sock], [], [], 3)[0]
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if not ready:
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raise self.EClose("ignoring socket not ready")
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# Peek, but do not read the data so that we have a opportunity
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# to SSL wrap the socket first
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handshake = sock.recv(1024, socket.MSG_PEEK)
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#self.msg("Handshake [%s]" % repr(handshake))
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if handshake == "":
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raise self.EClose("ignoring empty handshake")
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elif handshake.startswith("<policy-file-request/>"):
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# Answer Flash policy request
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handshake = sock.recv(1024)
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sock.send(self.policy_response)
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raise self.EClose("Sending flash policy response")
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elif handshake[0] in ("\x16", "\x80"):
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# SSL wrap the connection
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if not os.path.exists(self.cert):
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raise self.EClose("SSL connection but '%s' not found"
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% self.cert)
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try:
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retsock = ssl.wrap_socket(
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sock,
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server_side=True,
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certfile=self.cert,
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keyfile=self.key)
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except ssl.SSLError, x:
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if x.args[0] == ssl.SSL_ERROR_EOF:
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raise self.EClose("")
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else:
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raise
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scheme = "wss"
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stype = "SSL/TLS (wss://)"
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elif self.ssl_only:
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raise self.EClose("non-SSL connection received but disallowed")
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else:
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retsock = sock
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scheme = "ws"
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stype = "Plain non-SSL (ws://)"
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# Now get the data from the socket
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handshake = retsock.recv(4096)
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if len(handshake) == 0:
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raise self.EClose("Client closed during handshake")
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# Check for and handle normal web requests
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if handshake.startswith('GET ') and \
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handshake.find('Upgrade: WebSocket\r\n') == -1:
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if not self.web:
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raise self.EClose("Normal web request received but disallowed")
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sh = SplitHTTPHandler(handshake, retsock, address)
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if sh.last_code < 200 or sh.last_code >= 300:
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raise self.EClose(sh.last_message)
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elif self.verbose:
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raise self.EClose(sh.last_message)
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else:
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raise self.EClose("")
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#self.msg("handshake: " + repr(handshake))
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# Parse client WebSockets handshake
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h = self.parse_handshake(handshake)
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if h.get('key3'):
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trailer = self.gen_md5(h)
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pre = "Sec-"
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ver = 76
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else:
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trailer = ""
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pre = ""
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ver = 75
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self.msg("%s: %s WebSocket connection (version %s)"
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% (address[0], stype, ver))
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# Send server WebSockets handshake response
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response = self.server_handshake % (pre, h['Origin'], pre,
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scheme, h['Host'], h['path'], pre, trailer)
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#self.msg("sending response:", repr(response))
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retsock.send(response)
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# Return the WebSockets socket which may be SSL wrapped
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return retsock
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#
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# Events that can/should be overridden in sub-classes
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#
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def started(self):
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""" Called after WebSockets startup """
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self.vmsg("WebSockets server started")
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def poll(self):
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""" Run periodically while waiting for connections. """
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#self.vmsg("Running poll()")
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pass
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def top_SIGCHLD(self, sig, stack):
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# Reap zombies after calling child SIGCHLD handler
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self.do_SIGCHLD(sig, stack)
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self.vmsg("Got SIGCHLD, reaping zombies")
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try:
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result = os.waitpid(-1, os.WNOHANG)
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while result[0]:
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self.vmsg("Reaped child process %s" % result[0])
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result = os.waitpid(-1, os.WNOHANG)
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except (OSError):
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pass
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def do_SIGCHLD(self, sig, stack):
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pass
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def do_SIGINT(self, sig, stack):
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self.msg("Got SIGINT, exiting")
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sys.exit(0)
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def new_client(self, client):
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""" Do something with a WebSockets client connection. """
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raise("WebSocketServer.new_client() must be overloaded")
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def start_server(self):
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"""
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Daemonize if requested. Listen for for connections. Run
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do_handshake() method for each connection. If the connection
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is a WebSockets client then call new_client() method (which must
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be overridden) for each new client connection.
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"""
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lsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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lsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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lsock.bind((self.listen_host, self.listen_port))
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lsock.listen(100)
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if self.daemon:
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self.daemonize(self, keepfd=lsock.fileno())
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self.started() # Some things need to happen after daemonizing
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# Reep zombies
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signal.signal(signal.SIGCHLD, self.top_SIGCHLD)
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signal.signal(signal.SIGINT, self.do_SIGINT)
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while True:
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try:
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try:
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csock = startsock = None
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pid = err = 0
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try:
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self.poll()
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ready = select.select([lsock], [], [], 1)[0];
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if lsock in ready:
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startsock, address = lsock.accept()
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else:
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continue
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except Exception, exc:
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if hasattr(exc, 'errno'):
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err = exc.errno
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else:
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err = exc[0]
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if err == errno.EINTR:
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self.vmsg("Ignoring interrupted syscall")
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continue
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else:
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raise
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self.vmsg('%s: forking handler' % address[0])
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pid = os.fork()
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if pid == 0:
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# handler process
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csock = self.do_handshake(startsock, address)
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self.new_client(csock)
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else:
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# parent process
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self.handler_id += 1
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except self.EClose, exc:
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# Connection was not a WebSockets connection
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if exc.args[0]:
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self.msg("%s: %s" % (address[0], exc.args[0]))
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except KeyboardInterrupt, exc:
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pass
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except Exception, exc:
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self.msg("handler exception: %s" % str(exc))
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if self.verbose:
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self.msg(traceback.format_exc())
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finally:
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if csock and csock != startsock:
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csock.close()
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if startsock:
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startsock.close()
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if pid == 0:
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break # Child process exits
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# HTTP handler with request from a string and response to a socket
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class SplitHTTPHandler(SimpleHTTPRequestHandler):
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def __init__(self, req, resp, addr):
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# Save the response socket
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self.response = resp
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SimpleHTTPRequestHandler.__init__(self, req, addr, object())
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def setup(self):
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self.connection = self.response
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# Duck type request string to file object
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self.rfile = StringIO(self.request)
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self.wfile = self.connection.makefile('wb', self.wbufsize)
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def send_response(self, code, message=None):
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# Save the status code
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self.last_code = code
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SimpleHTTPRequestHandler.send_response(self, code, message)
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def log_message(self, f, *args):
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# Save instead of printing
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self.last_message = f % args
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