scripts/get-tor-exits

   1 #!/usr/bin/env python3
   2 # -*- coding: utf-8 -*-
   3 #
   4 # This file is part of BridgeDB, a Tor bridge distribution system.
   5 #
   6 # :authors: Isis Lovecruft 0xA3ADB67A2CDB8B35 <isis@torproject.org>
   7 #           please also see AUTHORS file
   8 # :copyright: (c) 2013 Isis Lovecruft
   9 #             (c) 2007-2013, The Tor Project, Inc.
  10 #             (c) 2007-2013, all entities within the AUTHORS file
  11 # :license: 3-clause BSD, see included LICENSE for information
  12
  13 """get-tor-exits -- Download the current list of Tor exit relays."""
  14
  15 from __future__ import print_function
  16
  17 import os.path
  18 import socket
  19 import sys
  20 import io
  21
  22 from ipaddress import IPv4Address
  23
  24 from OpenSSL import SSL
  25
  26 from twisted.python import log
  27 from twisted.python import usage
  28 from twisted.names import client as dnsclient
  29 from twisted.names import error as dnserror
  30 from twisted.web import client
  31 from twisted.internet import defer
  32 from twisted.internet import protocol
  33 from twisted.internet import reactor
  34 from twisted.internet import ssl
  35 from twisted.internet.error import ConnectionRefusedError
  36 from twisted.internet.error import DNSLookupError
  37 from twisted.internet.error import TimeoutError
  38
  39
  40 log.startLogging(sys.stderr, setStdout=False)
  41
  42
  43 def backupFile(filename):
  44     """Move our old exit list file so that we don't append to it."""
  45     if os.path.isfile(filename):
  46         backup = filename + '.bak'
  47         log.msg("get-tor-exits: Moving old exit list file to %s"
  48                       % backup)
  49         os.renames(filename, backup)
  50
  51 def getSelfIPAddress():
  52     """Get external IP address, to ask check which relays can exit to here.
  53
  54     TODO: This is blocking. Make it use Twisted.
  55     """
  56     ip = s = None
  57     try:
  58         s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  59         s.connect(('bridges.torproject.org', 443))
  60         name = s.getsockname()[0]
  61         ip = IPv4Address(name)
  62         if ip.is_link_local or ip.is_private or ip.is_reserved:
  63             name = s.getpeername()[0]
  64             ip = IPv4Address(name)
  65     except ValueError as error:
  66         log.err("get-tor-exits: A socket gave us something that wasn't an IP: %s"
  67                 % error)
  68     except Exception as error:
  69         log.err("get-tor-exits: Unhandled Exception: %s\n%s\n"
  70                 % (error.message, error))
  71     finally:
  72         if s is not None:
  73             s.close()
  74     return ip.compressed
  75
  76 def handle(failure):
  77     """Handle a **failure**."""
  78     if failure.type == ConnectionRefusedError:
  79         log.msg("get-tor-exits: Could not download exitlist; connection was refused.")
  80     elif failure.type == DNSLookupError:
  81         log.msg("get-tor-exits: Could not download exitlist; domain resolution failed.")
  82     elif failure.type == TimeoutError:
  83         log.msg("get-tor-exits: Could not download exitlist; connection timed out.")
  84
  85     failure.trap(ConnectionRefusedError, DNSLookupError, TimeoutError)
  86
  87 def writeToFile(response, filename):
  88     log.msg("get-tor-exits: Downloading list of Tor exit relays.")
  89     finished = defer.Deferred()
  90     response.deliverBody(FileWriter(finished, filename))
  91     return finished
  92
  93
  94 class GetTorExitsOptions(usage.Options):
  95     """Options for this script"""
  96     optFlags = [['stdout', 's', "Write results to stdout instead of file"]]
  97     optParameters = [['file', 'f', 'exit-list', "File to write results to"],
  98                      ['address', 'a', '1.1.1.1', "Only exits which can reach this address"],
  99                      ['port', 'p', 443, "Only exits which can reach this port"]]
 100
 101
 102 class FileWriter(protocol.Protocol):
 103     """Read a downloaded file incrementally and write to file."""
 104     def __init__(self, finished, file):
 105         """Create a FileWriter.
 106
 107         .. warning:: We currently only handle the first 2MB of a file. Files
 108             over 2MB will be truncated prematurely.
 109
 110         :param finished: A :class:`~twisted.internet.defer.Deferred` which
 111             will fire when another portion of the download is complete.
 112         """
 113         self.finished = finished
 114         self.remaining = 1024 * 1024 * 2
 115         self.fh = file
 116
 117     def dataReceived(self, bytes):
 118         """Write a portion of the download with ``bytes`` size to disk."""
 119         if self.remaining:
 120             display = bytes[:self.remaining]
 121             self.fh.write(display.decode("utf-8"))
 122             self.fh.flush()
 123             self.remaining -= len(display)
 124
 125     def connectionLost(self, reason):
 126         """Called when the download is complete."""
 127         log.msg('get-tor-exits: Finished receiving exit list: %s'
 128                  % reason.getErrorMessage())
 129         self.finished.callback(None)
 130
 131
 132 def main(filename=None, address=None, port=None):
 133
 134     fh = filename
 135     if filename:
 136         if (not isinstance(filename, io.TextIOBase)) and (filename is not sys.stdout):
 137             fh = open(filename, 'w')
 138
 139     if not address:
 140         address = getSelfIPAddress()
 141
 142     check  = "https://check.torproject.org/torbulkexitlist"
 143     params = []
 144
 145     params.append('ip=%s' % address)
 146     if port is not None:
 147         params.append("port=%s" % port)
 148
 149     check += '?' + '&'.join(params)
 150
 151     log.msg("get-tor-exits: Requesting %s..." % check)
 152
 153     agent = client.Agent(reactor)
 154     d = agent.request(b"GET", check.encode("utf-8"))
 155     d.addCallback(writeToFile, fh)
 156     d.addErrback(handle)
 157     d.addCallbacks(log.msg, log.err)
 158
 159     if not reactor.running:
 160         d.addCallback(lambda ignored: reactor.stop())
 161         reactor.run()
 162
 163     if filename:
 164         if (not isinstance(filename, io.TextIOBase)) and (filename is not sys.stdout):
 165             fh.flush()
 166             fh.close()
 167
 168
 169 if __name__ == "__main__":
 170     try:
 171         options = GetTorExitsOptions()
 172         options.parseOptions()
 173     except usage.UsageError as error:
 174         log.err(error)
 175         raise SystemExit(options.getUsage())
 176
 177     if options['stdout']:
 178         filename = sys.stdout
 179     elif options['file']:
 180         filename = options['file']
 181         log.msg("get-tor-exits: Saving Tor exit relay list to file: '%s'"
 182                 % filename)
 183         backupFile(filename)
 184
 185     main(filename, options['address'], options['port'])