cheatproxy.py

   1 #!/usr/bin/env python
   2
   3 """A basic HTTP proxy server that intercepts communication with
   4 BitTorrent trackers and optionally spoofs the amount of data
   5 uploaded. Free from artificial colours and preservatives. Web 2.0
   6 compatible."""
   7
   8 import getopt
   9 import logging
  10 import select
  11 import socket
  12 import sys
  13 import urlparse
  14
  15 import BaseHTTPServer
  16
  17 import cheatbt
  18
  19 class CheatHandler(BaseHTTPServer.BaseHTTPRequestHandler):
  20     """Used by HTTPServer to handle HTTP requests"""
  21
  22     mappings = {}
  23
  24     def do_GET(self):
  25         """Called by BaseHTTPRequestHandler when a GET request is
  26         received from a client."""
  27
  28         cheatpath = cheatbt.cheat(self.path, CheatHandler.mappings)
  29
  30         logger = logging.getLogger("cheatproxy")
  31         logger.info(cheatpath)
  32
  33         (scheme, netloc, path, params, query, fragment) = \
  34             urlparse.urlparse(cheatpath, 'http')
  35
  36         # TODO: https support.
  37         if scheme != 'http' or fragment or not netloc:
  38             self.send_error(501)
  39             return
  40
  41         soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  42
  43         try:
  44             if self._connect_to(netloc, soc):
  45                 request = urlparse.urlunparse(('', '', path, params, query, ''))
  46                 soc.send("%s %s %s\r\n" % (self.command, request,
  47                                            self.request_version))
  48                 self.headers['Connection'] = 'close'
  49                 del self.headers['Proxy-Connection']
  50                 # This is naughty. But rfc822.Message, which self.headers is a
  51                 # subclass of, insists on converting headers to lowercase when
  52                 # accessed conventionally (i.e. as a dict).
  53                 for header in self.headers.headers:
  54                     soc.send(header.strip() + '\r\n')
  55                     logger.debug(repr(header))
  56                 soc.send("\r\n")
  57                 self._read_write(soc)
  58         finally:
  59             soc.close()
  60             self.connection.close()
  61
  62     def _connect_to(self, netloc, soc):
  63         """Attempt to establish a connection to the tracker."""
  64
  65         i = netloc.find(':')
  66         if i >= 0:
  67             host_port = (netloc[:i], int(netloc[i+1:]))
  68         else:
  69             host_port = (netloc, 80)
  70
  71         try:
  72             soc.connect(host_port)
  73         except socket.error:
  74             self.send_error(502)
  75             return False
  76
  77         return True
  78
  79     def _read_write(self, soc, max_idling=20):
  80         """Pass data between the remote server and the client. I
  81         think."""
  82
  83         rlist = [self.connection, soc]
  84         wlist = []
  85         count = 0
  86         while True:
  87             count += 1
  88             (ins, _, exs) = select.select(rlist, wlist, rlist, 3)
  89             if exs:
  90                 break
  91             if ins:
  92                 for i in ins:
  93                     if i is soc:
  94                         out = self.connection
  95                     else:
  96                         out = soc
  97                     data = i.recv(8192)
  98                     if data:
  99                         out.send(data)
 100                         count = 0
 101             else:
 102                 pass
 103             if count == max_idling:
 104                 break
 105
 106 def usage():
 107     """Prints usage information and exits."""
 108
 109     print """
 110 usage: %s [-b host] [-p port] [-f file] [-v] [-d] [-h]
 111
 112   -b host  IP or hostname to bind to. Default is localhost.
 113   -p port  Port to listen on. Default is 8000.
 114   -f file  Mappings file.
 115   -v       Verbose output.
 116   -d       Debug output.
 117   -h       What you're reading.
 118 """ % sys.argv[0]
 119     sys.exit(1)
 120
 121 def main():
 122     host = "localhost"
 123     port = 8000
 124
 125     rootlogger = logging.getLogger("")
 126     ch = logging.StreamHandler()
 127     ch.setFormatter(
 128         logging.Formatter("%(asctime)s:%(name)s:%(levelname)s %(message)s"))
 129     rootlogger.addHandler(ch)
 130
 131     try:
 132         opts, _ = getopt.getopt(sys.argv[1:], "b:f:p:hvd")
 133     except getopt.GetoptError:
 134         usage()
 135
 136     for opt, val in opts:
 137         if opt == "-b":
 138             host = val
 139         if opt == "-p":
 140             port = int(val)
 141         if opt == "-f":
 142             CheatHandler.mappings = cheatbt.load_mappings(val)
 143         if opt == "-v":
 144             rootlogger.setLevel(logging.INFO)
 145         if opt == "-d":
 146             rootlogger.setLevel(logging.DEBUG)
 147         if opt == "-h":
 148             usage()
 149
 150     httpd = BaseHTTPServer.HTTPServer((host, port), CheatHandler)
 151
 152     logger = logging.getLogger("cheatproxy")
 153     logger.info("listening on %s:%d" % (host, port))
 154
 155     httpd.serve_forever()
 156
 157 if __name__ == "__main__":
 158     try:
 159         main()
 160     except KeyboardInterrupt:
 161         logging.shutdown()
 162         sys.exit()