socks5_server.py

# Modified From https://github.com/rushter/socks5

import logging
import select
import socket
import struct
from socketserver import ThreadingMixIn, TCPServer, StreamRequestHandler

logging.basicConfig(level=logging.DEBUG)
SOCKS_VERSION = 5


class ThreadingTCPServer(ThreadingMixIn, TCPServer):
    pass


class SocksProxy(StreamRequestHandler):
    username = 'username'
    password = 'password'

    def handle(self):
        # logging.info('Accepting connection from %s:%s' % self.client_address)

        # greeting header
        # read and unpack 2 bytes from a client
        header = self.connection.recv(2)
        version, nmethods = struct.unpack("!BB", header)

        # socks 5
        assert version == SOCKS_VERSION
        assert nmethods > 0

        # send welcome message
        self.connection.recv(nmethods)
        self.connection.sendall(struct.pack("!BB", SOCKS_VERSION, 0))

        # request
        version, cmd, _, address_type = struct.unpack(
            "!BBBB", self.connection.recv(4))
        assert version == SOCKS_VERSION

        if address_type == 1:  # IPv4
            address = socket.inet_ntoa(self.connection.recv(4))
        elif address_type == 3:  # Domain name
            domain_length = self.connection.recv(1)[0]
            address = self.connection.recv(domain_length)
            address = socket.gethostbyname(address)
        port = struct.unpack('!H', self.connection.recv(2))[0]

        # reply
        try:
            if cmd == 1:  # CONNECT
                remote = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                remote.connect((address, port))
                bind_address = remote.getsockname()
            else:
                self.server.close_request(self.request)

            addr = struct.unpack("!I", socket.inet_aton(bind_address[0]))[0]
            port = bind_address[1]
            reply = struct.pack("!BBBBIH", SOCKS_VERSION, 0, 0, 1,
                                addr, port)

        except Exception as err:
            logging.error(err)
            # return connection refused error
            reply = self.generate_failed_reply(address_type, 5)

        self.connection.sendall(reply)

        # establish data exchange
        if reply[1] == 0 and cmd == 1:
            self.exchange_loop(self.connection, remote)

        self.server.close_request(self.request)

    def generate_failed_reply(self, address_type, error_number):
        return struct.pack("!BBBBIH", SOCKS_VERSION, error_number, 0, address_type, 0, 0)

    def exchange_loop(self, client, remote):

        while True:

            # wait until client or remote is available for read
            r, w, e = select.select([client, remote], [], [])

            if client in r:
                data = client.recv(4096)
                if remote.send(data) <= 0:
                    break

            if remote in r:
                data = remote.recv(4096)
                if client.send(data) <= 0:
                    break


if __name__ == '__main__':
    with ThreadingTCPServer(('127.0.0.1', 9011), SocksProxy) as server:
        server.serve_forever()