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#!/usr/bin/env python3
"""Minimal non-feature complete socks proxy"""
import socket
from struct import pack, unpack
import threading
import sys
import traceback
from socketserver import StreamRequestHandler, ThreadingTCPServer
def debug(s):
print('socks.py: ', s)
sys.stdout.flush()
def error(s):
print('socks.py, ERROR: ', s)
sys.stdout.flush()
class MyTCPServer(ThreadingTCPServer):
allow_reuse_address = True
def handle_timeout(self):
raise Exception('socks.py: timeout')
CLOSE = object()
VERSION = b'\x05'
NOAUTH = b'\x00'
USERPASS = b'\x02'
CONNECT = b'\x01'
UDP_ASSOCIATE = b'\x03'
IPV4 = b'\x01'
IPV6 = b'\x04'
DOMAIN_NAME = b'\x03'
SUCCESS = b'\x00'
password = None
username = None
allow_v4 = False
def send(dest, msg):
if msg == CLOSE:
try:
dest.shutdown(socket.SHUT_WR)
except Exception:
pass
dest.close()
return 0
else:
return dest.sendall(msg)
def recv(source, n):
data = source.recv(n)
if data == b'':
return CLOSE
else:
return data
def forward(source, dest, name):
while True:
data = recv(source, 4000)
if data == CLOSE:
send(dest, CLOSE)
debug('%s hung up' % name)
return
# debug('Forwarding (%d) %r' % (len(data), data))
send(dest, data)
def spawn_forwarder(source, dest, name):
t = threading.Thread(target=forward, args=(source, dest, name))
t.daemon = True
t.start()
class SocksHandler(StreamRequestHandler):
"""Highly feature incomplete SOCKS 5 implementation"""
def close_request(self):
self.server.close_request(self.request)
def read(self, n):
data = b''
while len(data) < n:
extra = self.rfile.read(n)
if extra == b'':
raise Exception('Connection closed')
data += extra
return data
def handle(self):
try:
self.inner_handle()
except Exception:
error("Unhandled exception")
traceback.print_exc(file=sys.stdout)
sys.stdout.flush()
def inner_handle(self):
# IMPROVEMENT: Report who requests are from in logging
# IMPROVEMENT: Timeout on client
debug('Connection - authenticating')
version = self.read(1)
if allow_v4 and version == b'\x04':
cmd = self.read(1)
if cmd != CONNECT and cmd != UDP_ASSOCIATE:
error('Only supports connect and udp-associate method not (%r) closing' % cmd)
self.close_request()
return
raw_dest_port = self.read(2)
dest_port, = unpack('>H', raw_dest_port)
raw_dest_address = self.read(4)
dest_address = '.'.join(map(str, unpack('>4B', raw_dest_address)))
user_id = b''
c = self.read(1)
while c != b'\0':
user_id += c
c = self.read(1)
outbound_sock = socket.socket(socket.AF_INET)
out_address = socket.getaddrinfo(dest_address, dest_port)[0][4]
debug("Creating forwarder connection to %s:%d" % (out_address[0], out_address[1]))
outbound_sock.connect(out_address)
self.send_reply_v4(outbound_sock.getsockname())
spawn_forwarder(outbound_sock, self.request, 'destination')
forward(self.request, outbound_sock, 'client')
return
if version != b'\x05':
error('Wrong version number (%r) closing...' % version)
self.close_request()
return
nmethods = ord(self.read(1))
method_list = self.read(nmethods)
global password
global username
if password is None and NOAUTH in method_list:
self.send_no_auth_method()
debug('Authenticated (no-auth)')
elif USERPASS in method_list:
self.send_user_pass_auth_method()
auth_version = self.read(1)
if auth_version != b'\x01':
error('Wrong sub-negotiation version number (%r) closing...' % version)
self.close_request()
return
usr_len = ord(self.read(1))
usr_name = self.read(usr_len)
pwd_len = ord(self.read(1))
pwd = self.read(pwd_len)
if usr_name != username.encode() or pwd != password.encode():
error('Invalid username or password')
self.close_request()
return
debug('Authenticated (user/password)')
self.send_authenticated()
else:
error('Server only supports NOAUTH and user/pass')
self.send_no_method()
return
# If we were authenticating it would go here
version = self.read(1)
cmd = self.read(1)
zero = self.read(1)
address_type = self.read(1)
if version != b'\x05':
error('Wrong version number (%r) closing...' % version)
self.close_request()
elif cmd != CONNECT and cmd != UDP_ASSOCIATE:
error('Only supports connect and udp-associate method not (%r) closing' % cmd)
self.close_request()
elif zero != b'\x00':
error('Mangled request. Reserved field (%r) is not null' % zero)
self.close_request()
if address_type == IPV4:
raw_dest_address = self.read(4)
dest_address = '.'.join(map(str, unpack('>4B', raw_dest_address)))
elif address_type == IPV6:
raw_dest_address = self.read(16)
dest_address = ":".join([hex(x)[2:] for x in unpack('>8H', raw_dest_address)])
elif address_type == DOMAIN_NAME:
dns_length = ord(self.read(1))
dns_name = self.read(dns_length)
dest_address = dns_name
else:
error('Unknown addressing (%r)' % address_type)
self.close_request()
raw_dest_port = self.read(2)
dest_port, = unpack('>H', raw_dest_port)
if address_type == IPV6:
outbound_sock = socket.socket(socket.AF_INET6)
else:
outbound_sock = socket.socket(socket.AF_INET)
try:
out_address = socket.getaddrinfo(dest_address, dest_port)[0][4]
except Exception as e:
error('%s' % e)
traceback.print_exc(file=sys.stdout)
return
if cmd == UDP_ASSOCIATE:
debug("no UDP support yet, closing")
return
debug("Creating forwarder connection to %s:%d" % (out_address[0], out_address[1]))
try:
outbound_sock.connect(out_address)
except Exception as e:
error('%s' % e)
traceback.print_exc(file=sys.stdout)
return
if address_type == IPV6:
self.send_reply6(outbound_sock.getsockname())
else:
self.send_reply(outbound_sock.getsockname())
spawn_forwarder(outbound_sock, self.request, 'destination')
try:
forward(self.request, outbound_sock, 'client')
except Exception as e:
error('%s' % e)
traceback.print_exc(file=sys.stdout)
def send_reply_v4(self, xxx_todo_changeme):
(bind_addr, bind_port) = xxx_todo_changeme
self.wfile.write(b'\0\x5a\0\0\0\0\0\0')
self.wfile.flush()
def send_reply(self, xxx_todo_changeme1):
(bind_addr, bind_port) = xxx_todo_changeme1
bind_tuple = tuple(map(int, bind_addr.split('.')))
full_address = bind_tuple + (bind_port,)
debug('Setting up forwarding port %r' % (full_address,))
msg = pack('>cccc4BH', VERSION, SUCCESS, b'\x00', IPV4, *full_address)
self.wfile.write(msg)
def send_reply6(self, xxx_todo_changeme2):
(bind_addr, bind_port, unused1, unused2) = xxx_todo_changeme2
bind_tuple = tuple([int(x, 16) for x in bind_addr.split(':')])
full_address = bind_tuple + (bind_port,)
debug('Setting up forwarding port %r' % (full_address,))
msg = pack('>cccc8HH', VERSION, SUCCESS, b'\x00', IPV6, *full_address)
self.wfile.write(msg)
def send_no_method(self):
self.wfile.write(b'\x05\xff')
self.close_request()
def send_no_auth_method(self):
self.wfile.write(b'\x05\x00')
self.wfile.flush()
def send_user_pass_auth_method(self):
self.wfile.write(b'\x05\x02')
self.wfile.flush()
def send_authenticated(self):
self.wfile.write(b'\x01\x00')
self.wfile.flush()
if __name__ == '__main__':
debug('starting socks.py %s' % " ".join(sys.argv))
debug('python version: %s' % sys.version_info.__str__())
listen_port = 8002
i = 1
while i < len(sys.argv):
if sys.argv[i] == '--username':
username = sys.argv[i + 1]
i += 1
elif sys.argv[i] == '--password':
password = sys.argv[i + 1]
i += 1
elif sys.argv[i] == '--port':
listen_port = int(sys.argv[i + 1])
i += 1
elif sys.argv[i] == '--allow-v4':
allow_v4 = True
else:
if sys.argv[i] != '--help':
debug('unknown option "%s"' % sys.argv[i])
print('usage: socks.py [--username <user> --password <password>] [--port <listen-port>]')
sys.stdout.flush()
sys.exit(1)
i += 1
debug('Listening on port %d...' % listen_port)
server = MyTCPServer(('localhost', listen_port), SocksHandler)
server.timeout = 190
while True:
server.handle_request()
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