#!/usr/bin/python # -*- coding: utf-8 -*- # Copyright (c) 2014 clowwindy # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the "Software"), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # SOFTWARE. # SOCKS5 UDP Request # +----+------+------+----------+----------+----------+ # |RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA | # +----+------+------+----------+----------+----------+ # | 2 | 1 | 1 | Variable | 2 | Variable | # +----+------+------+----------+----------+----------+ # SOCKS5 UDP Response # +----+------+------+----------+----------+----------+ # |RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA | # +----+------+------+----------+----------+----------+ # | 2 | 1 | 1 | Variable | 2 | Variable | # +----+------+------+----------+----------+----------+ # shadowsocks UDP Request (before encrypted) # +------+----------+----------+----------+ # | ATYP | DST.ADDR | DST.PORT | DATA | # +------+----------+----------+----------+ # | 1 | Variable | 2 | Variable | # +------+----------+----------+----------+ # shadowsocks UDP Response (before encrypted) # +------+----------+----------+----------+ # | ATYP | DST.ADDR | DST.PORT | DATA | # +------+----------+----------+----------+ # | 1 | Variable | 2 | Variable | # +------+----------+----------+----------+ # shadowsocks UDP Request and Response (after encrypted) # +-------+--------------+ # | IV | PAYLOAD | # +-------+--------------+ # | Fixed | Variable | # +-------+--------------+ # HOW TO NAME THINGS # ------------------ # `dest` means destination server, which is from DST fields in the SOCKS5 # request # `local` means local server of shadowsocks # `remote` means remote server of shadowsocks # `client` means UDP clients that connects to other servers # `server` means the UDP server that handles user requests import time import socket import logging import struct import errno import random import encrypt import eventloop import lru_cache from common import parse_header BUF_SIZE = 65536 def client_key(a, b, c, d): return '%s:%s:%s:%s' % (a, b, c, d) class UDPRelay(object): def __init__(self, config, dns_resolver, is_local): self._config = config if is_local: self._listen_addr = config['local_address'] self._listen_port = config['local_port'] self._remote_addr = config['server'] self._remote_port = config['server_port'] else: self._listen_addr = config['server'] self._listen_port = config['server_port'] self._remote_addr = None self._remote_port = None self._dns_resolver = dns_resolver self._password = config['password'] self._method = config['method'] self._timeout = config['timeout'] self._is_local = is_local self._cache = lru_cache.LRUCache(timeout=config['timeout'], close_callback=self._close_client) self._client_fd_to_server_addr = \ lru_cache.LRUCache(timeout=config['timeout']) self._eventloop = None self._closed = False self._last_time = time.time() self._sockets = set() addrs = socket.getaddrinfo(self._listen_addr, self._listen_port, 0, socket.SOCK_DGRAM, socket.SOL_UDP) if len(addrs) == 0: raise Exception("can't get addrinfo for %s:%d" % (self._listen_addr, self._listen_port)) af, socktype, proto, canonname, sa = addrs[0] server_socket = socket.socket(af, socktype, proto) server_socket.bind((self._listen_addr, self._listen_port)) server_socket.setblocking(False) self._server_socket = server_socket def _get_a_server(self): server = self._config['server'] server_port = self._config['server_port'] if type(server_port) == list: server_port = random.choice(server_port) logging.debug('chosen server: %s:%d', server, server_port) # TODO support multiple server IP return server, server_port def _close_client(self, client): if hasattr(client, 'close'): self._sockets.remove(client.fileno()) self._eventloop.remove(client) client.close() else: # just an address pass def _handle_server(self): server = self._server_socket data, r_addr = server.recvfrom(BUF_SIZE) if not data: logging.debug('UDP handle_server: data is empty') if self._is_local: frag = ord(data[2]) if frag != 0: logging.warn('drop a message since frag is not 0') return else: data = data[3:] else: data = encrypt.encrypt_all(self._password, self._method, 0, data) # decrypt data if not data: logging.debug('UDP handle_server: data is empty after decrypt') return header_result = parse_header(data) if header_result is None: return addrtype, dest_addr, dest_port, header_length = header_result if self._is_local: server_addr, server_port = self._get_a_server() else: server_addr, server_port = dest_addr, dest_port key = client_key(r_addr[0], r_addr[1], dest_addr, dest_port) client = self._cache.get(key, None) if not client: # TODO async getaddrinfo addrs = socket.getaddrinfo(server_addr, server_port, 0, socket.SOCK_DGRAM, socket.SOL_UDP) if addrs: af, socktype, proto, canonname, sa = addrs[0] client = socket.socket(af, socktype, proto) client.setblocking(False) self._cache[key] = client self._client_fd_to_server_addr[client.fileno()] = r_addr else: # drop return self._sockets.add(client.fileno()) self._eventloop.add(client, eventloop.POLL_IN) if self._is_local: data = encrypt.encrypt_all(self._password, self._method, 1, data) if not data: return else: data = data[header_length:] if not data: return try: client.sendto(data, (server_addr, server_port)) except IOError as e: err = eventloop.errno_from_exception(e) if err in (errno.EINPROGRESS, errno.EAGAIN): pass else: logging.error(e) def _handle_client(self, sock): data, r_addr = sock.recvfrom(BUF_SIZE) if not data: logging.debug('UDP handle_client: data is empty') return if not self._is_local: addrlen = len(r_addr[0]) if addrlen > 255: # drop return data = '\x03' + chr(addrlen) + r_addr[0] + \ struct.pack('>H', r_addr[1]) + data response = encrypt.encrypt_all(self._password, self._method, 1, data) if not response: return else: data = encrypt.encrypt_all(self._password, self._method, 0, data) if not data: return header_result = parse_header(data) if header_result is None: return # addrtype, dest_addr, dest_port, header_length = header_result response = '\x00\x00\x00' + data client_addr = self._client_fd_to_server_addr.get(sock.fileno()) if client_addr: self._server_socket.sendto(response, client_addr) else: # this packet is from somewhere else we know # simply drop that packet pass def add_to_loop(self, loop): if self._eventloop: raise Exception('already add to loop') if self._closed: raise Exception('already closed') self._eventloop = loop loop.add_handler(self._handle_events) server_socket = self._server_socket self._eventloop.add(server_socket, eventloop.POLL_IN | eventloop.POLL_ERR) def _handle_events(self, events): for sock, fd, event in events: if sock == self._server_socket: if event & eventloop.POLL_ERR: logging.error('UDP server_socket err') self._handle_server() elif sock and (fd in self._sockets): if event & eventloop.POLL_ERR: logging.error('UDP client_socket err') self._handle_client(sock) now = time.time() if now - self._last_time > 3.5: self._cache.sweep() if now - self._last_time > 7: self._client_fd_to_server_addr.sweep() self._last_time = now def close(self): self._closed = True self._server_socket.close()