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# -*- test-case-name: twisted.test.test_socks -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Implementation of the SOCKSv4 protocol.
"""
import socket
import string
# python imports
import struct
import time
# twisted imports
from twisted.internet import defer, protocol, reactor
from twisted.python import log
class SOCKSv4Outgoing(protocol.Protocol):
def __init__(self, socks):
self.socks = socks
def connectionMade(self):
peer = self.transport.getPeer()
self.socks.makeReply(90, 0, port=peer.port, ip=peer.host)
self.socks.otherConn = self
def connectionLost(self, reason):
self.socks.transport.loseConnection()
def dataReceived(self, data):
self.socks.write(data)
def write(self, data):
self.socks.log(self, data)
self.transport.write(data)
class SOCKSv4Incoming(protocol.Protocol):
def __init__(self, socks):
self.socks = socks
self.socks.otherConn = self
def connectionLost(self, reason):
self.socks.transport.loseConnection()
def dataReceived(self, data):
self.socks.write(data)
def write(self, data):
self.socks.log(self, data)
self.transport.write(data)
class SOCKSv4(protocol.Protocol):
"""
An implementation of the SOCKSv4 protocol.
@type logging: L{str} or L{None}
@ivar logging: If not L{None}, the name of the logfile to which connection
information will be written.
@type reactor: object providing L{twisted.internet.interfaces.IReactorTCP}
@ivar reactor: The reactor used to create connections.
@type buf: L{str}
@ivar buf: Part of a SOCKSv4 connection request.
@type otherConn: C{SOCKSv4Incoming}, C{SOCKSv4Outgoing} or L{None}
@ivar otherConn: Until the connection has been established, C{otherConn} is
L{None}. After that, it is the proxy-to-destination protocol instance
along which the client's connection is being forwarded.
"""
def __init__(self, logging=None, reactor=reactor):
self.logging = logging
self.reactor = reactor
def connectionMade(self):
self.buf = b""
self.otherConn = None
def dataReceived(self, data):
"""
Called whenever data is received.
@type data: L{bytes}
@param data: Part or all of a SOCKSv4 packet.
"""
if self.otherConn:
self.otherConn.write(data)
return
self.buf = self.buf + data
completeBuffer = self.buf
if b"\000" in self.buf[8:]:
head, self.buf = self.buf[:8], self.buf[8:]
version, code, port = struct.unpack("!BBH", head[:4])
user, self.buf = self.buf.split(b"\000", 1)
if head[4:7] == b"\000\000\000" and head[7:8] != b"\000":
# An IP address of the form 0.0.0.X, where X is non-zero,
# signifies that this is a SOCKSv4a packet.
# If the complete packet hasn't been received, restore the
# buffer and wait for it.
if b"\000" not in self.buf:
self.buf = completeBuffer
return
server, self.buf = self.buf.split(b"\000", 1)
d = self.reactor.resolve(server)
d.addCallback(self._dataReceived2, user, version, code, port)
d.addErrback(lambda result, self=self: self.makeReply(91))
return
else:
server = socket.inet_ntoa(head[4:8])
self._dataReceived2(server, user, version, code, port)
def _dataReceived2(self, server, user, version, code, port):
"""
The second half of the SOCKS connection setup. For a SOCKSv4 packet this
is after the server address has been extracted from the header. For a
SOCKSv4a packet this is after the host name has been resolved.
@type server: L{str}
@param server: The IP address of the destination, represented as a
dotted quad.
@type user: L{str}
@param user: The username associated with the connection.
@type version: L{int}
@param version: The SOCKS protocol version number.
@type code: L{int}
@param code: The command code. 1 means establish a TCP/IP stream
connection, and 2 means establish a TCP/IP port binding.
@type port: L{int}
@param port: The port number associated with the connection.
"""
assert version == 4, "Bad version code: %s" % version
if not self.authorize(code, server, port, user):
self.makeReply(91)
return
if code == 1: # CONNECT
d = self.connectClass(server, port, SOCKSv4Outgoing, self)
d.addErrback(lambda result, self=self: self.makeReply(91))
elif code == 2: # BIND
d = self.listenClass(0, SOCKSv4IncomingFactory, self, server)
d.addCallback(lambda x, self=self: self.makeReply(90, 0, x[1], x[0]))
else:
raise RuntimeError(f"Bad Connect Code: {code}")
assert self.buf == b"", "hmm, still stuff in buffer... %s" % repr(self.buf)
def connectionLost(self, reason):
if self.otherConn:
self.otherConn.transport.loseConnection()
def authorize(self, code, server, port, user):
log.msg(
"code %s connection to %s:%s (user %s) authorized"
% (code, server, port, user)
)
return 1
def connectClass(self, host, port, klass, *args):
return protocol.ClientCreator(reactor, klass, *args).connectTCP(host, port)
def listenClass(self, port, klass, *args):
serv = reactor.listenTCP(port, klass(*args))
return defer.succeed(serv.getHost()[1:])
def makeReply(self, reply, version=0, port=0, ip="0.0.0.0"):
self.transport.write(
struct.pack("!BBH", version, reply, port) + socket.inet_aton(ip)
)
if reply != 90:
self.transport.loseConnection()
def write(self, data):
self.log(self, data)
self.transport.write(data)
def log(self, proto, data):
if not self.logging:
return
peer = self.transport.getPeer()
their_peer = self.otherConn.transport.getPeer()
f = open(self.logging, "a")
f.write(
"%s\t%s:%d %s %s:%d\n"
% (
time.ctime(),
peer.host,
peer.port,
((proto == self and "<") or ">"),
their_peer.host,
their_peer.port,
)
)
while data:
p, data = data[:16], data[16:]
f.write(string.join(map(lambda x: "%02X" % ord(x), p), " ") + " ")
f.write((16 - len(p)) * 3 * " ")
for c in p:
if len(repr(c)) > 3:
f.write(".")
else:
f.write(c)
f.write("\n")
f.write("\n")
f.close()
class SOCKSv4Factory(protocol.Factory):
"""
A factory for a SOCKSv4 proxy.
Constructor accepts one argument, a log file name.
"""
def __init__(self, log):
self.logging = log
def buildProtocol(self, addr):
return SOCKSv4(self.logging, reactor)
class SOCKSv4IncomingFactory(protocol.Factory):
"""
A utility class for building protocols for incoming connections.
"""
def __init__(self, socks, ip):
self.socks = socks
self.ip = ip
def buildProtocol(self, addr):
if addr[0] == self.ip:
self.ip = ""
self.socks.makeReply(90, 0)
return SOCKSv4Incoming(self.socks)
elif self.ip == "":
return None
else:
self.socks.makeReply(91, 0)
self.ip = ""
return None
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