#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# Copyright 2015 clowwindy
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
# 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
from __future__ import absolute_import, division, print_function, \
with_statement
import socket
import logging
import struct
import errno
import random
from shadowsocks import encrypt, eventloop, lru_cache, common, shell
from shadowsocks.common import parse_header, pack_addr
BUF_SIZE = 65536
def client_key(source_addr, server_af):
# notice this is server af, not dest af
return '%s:%s:%d' % (source_addr[0], source_addr[1], server_af)
class UDPRelay(object):
def __init__(self, config, dns_resolver, is_local, stat_callback=None):
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 = common.to_bytes(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._dns_cache = lru_cache.LRUCache(timeout=300)
self._eventloop = None
self._closed = False
self._sockets = set()
if 'forbidden_ip' in config:
self._forbidden_iplist = config['forbidden_ip']
else:
self._forbidden_iplist = None
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
self._stat_callback = stat_callback
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)
if type(server) == list:
server = random.choice(server)
logging.debug('chosen server: %s:%d', server, server_port)
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._stat_callback:
self._stat_callback(self._listen_port, len(data))
if self._is_local:
frag = common.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
addrs = self._dns_cache.get(server_addr, None)
if addrs is None:
addrs = socket.getaddrinfo(server_addr, server_port, 0,
socket.SOCK_DGRAM, socket.SOL_UDP)
if not addrs:
# drop
return
else:
self._dns_cache[server_addr] = addrs
af, socktype, proto, canonname, sa = addrs[0]
key = client_key(r_addr, af)
client = self._cache.get(key, None)
if not client:
# TODO async getaddrinfo
if self._forbidden_iplist:
if common.to_str(sa[0]) in self._forbidden_iplist:
logging.debug('IP %s is in forbidden list, drop' %
common.to_str(sa[0]))
# drop
return
client = socket.socket(af, socktype, proto)
client.setblocking(False)
self._cache[key] = client
self._client_fd_to_server_addr[client.fileno()] = r_addr
self._sockets.add(client.fileno())
self._eventloop.add(client, eventloop.POLL_IN, self)
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:
shell.print_exception(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 self._stat_callback:
self._stat_callback(self._listen_port, len(data))
if not self._is_local:
addrlen = len(r_addr[0])
if addrlen > 255:
# drop
return
data = pack_addr(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 = b'\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
server_socket = self._server_socket
self._eventloop.add(server_socket,
eventloop.POLL_IN | eventloop.POLL_ERR, self)
loop.add_periodic(self.handle_periodic)
def handle_event(self, sock, fd, event):
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)
def handle_periodic(self):
if self._closed:
if self._server_socket:
self._server_socket.close()
self._server_socket = None
for sock in self._sockets:
sock.close()
logging.info('closed UDP port %d', self._listen_port)
self._cache.sweep()
self._client_fd_to_server_addr.sweep()
def close(self, next_tick=False):
logging.debug('UDP close')
self._closed = True
if not next_tick:
if self._eventloop:
self._eventloop.remove_periodic(self.handle_periodic)
self._eventloop.remove(self._server_socket)
self._server_socket.close()
for client in list(self._cache.values()):
client.close()
