def handle_event(self, sock, fd, event):
     if sock == self._server_socket:
         if event & eventloop.POLL_ERR:
             logging.error('UDP server_socket err')
         try:
             self._handle_server()
         except Exception as e:
             shell.print_exception(e)
             if self._config['verbose']:
                 traceback.print_exc()
     elif sock and (fd in self._sockets):
         if event & eventloop.POLL_ERR:
             logging.error('UDP client_socket err')
         try:
             self._handle_client(sock)
         except Exception as e:
             shell.print_exception(e)
             if self._config['verbose']:
                 traceback.print_exc()
     else:
         if sock:
             handler = self._fd_to_handlers.get(fd, None)
             if handler:
                 handler.handle_event(sock, event)
         else:
             logging.warn('poll removed fd')
Exemplo n.º 2
0
 def handle_event(self, sock, fd, event):
     if sock == self._server_socket:
         if event & eventloop.POLL_ERR:
             logging.error('UDP server_socket err')
         try:
             self._handle_server()
         except Exception as e:
             shell.print_exception(e)
             if self._config['verbose']:
                 traceback.print_exc()
     elif sock and (fd in self._sockets):
         if event & eventloop.POLL_ERR:
             logging.error('UDP client_socket err')
         try:
             self._handle_client(sock)
         except Exception as e:
             shell.print_exception(e)
             if self._config['verbose']:
                 traceback.print_exc()
     else:
         if sock:
             handler = self._fd_to_handlers.get(fd, None)
             if handler:
                 handler.handle_event(sock, event)
         else:
             logging.warn('poll removed fd')
Exemplo n.º 3
0
def write_pid_file(pid_file, pid):
    import fcntl
    import stat

    try:
        fd = os.open(pid_file, os.O_RDWR | os.O_CREAT,
                     stat.S_IRUSR | stat.S_IWUSR)
    except OSError as e:
        shell.print_exception(e)
        return -1
    flags = fcntl.fcntl(fd, fcntl.F_GETFD)
    assert flags != -1
    flags |= fcntl.FD_CLOEXEC
    r = fcntl.fcntl(fd, fcntl.F_SETFD, flags)
    assert r != -1
    # There is no platform independent way to implement fcntl(fd, F_SETLK, &fl)
    # via fcntl.fcntl. So use lockf instead
    try:
        fcntl.lockf(fd, fcntl.LOCK_EX | fcntl.LOCK_NB, 0, 0, os.SEEK_SET)
    except IOError:
        r = os.read(fd, 32)
        if r:
            logging.error('already started at pid %s' % common.to_str(r))
        else:
            logging.error('already started')
        os.close(fd)
        return -1
    os.ftruncate(fd, 0)
    os.write(fd, common.to_bytes(str(pid)))
    return 0
    def run(self):
        events = []
        while not self._stopping:
            asap = False
            try:
                events = self.poll(TIMEOUT_PRECISION)
            except (OSError, IOError) as e:
                if errno_from_exception(e) in (errno.EPIPE, errno.EINTR):
                    # EPIPE: Happens when the client closes the connection
                    # EINTR: Happens when received a signal
                    # handles them as soon as possible
                    asap = True
                    logging.debug('poll:%s', e)
                else:
                    logging.error('poll:%s', e)
                    import traceback
                    traceback.print_exc()
                    continue

            handle = False
            for sock, fd, event in events:
                handler = self._fdmap.get(fd, None)
                if handler is not None:
                    handler = handler[1]
                    try:
                        handle = handler.handle_event(sock, fd, event) or handle
                    except (OSError, IOError) as e:
                        shell.print_exception(e)
            now = time.time()
            if asap or now - self._last_time >= TIMEOUT_PRECISION:
                for callback in self._periodic_callbacks:
                    callback()
                self._last_time = now
            if events and not handle:
                time.sleep(0.001)
Exemplo n.º 5
0
def main():
    shell.check_python()

    # fix py2exe
    if hasattr(sys, "frozen") and sys.frozen in \
            ("windows_exe", "console_exe"):
        p = os.path.dirname(os.path.abspath(sys.executable))
        os.chdir(p)

    config = shell.get_config(True)

    if not config.get('dns_ipv6', False):
        asyncdns.IPV6_CONNECTION_SUPPORT = False

    daemon.daemon_exec(config)
    logging.info(
        "local start with protocol[%s] password [%s] method [%s] obfs [%s] obfs_param [%s]"
        % (config['protocol'], config['password'], config['method'],
           config['obfs'], config['obfs_param']))

    try:
        logging.info("starting local at %s:%d" %
                     (config['local_address'], config['local_port']))

        dns_resolver = asyncdns.DNSResolver()
        tcp_server = tcprelay.TCPRelay(config, dns_resolver, True)
        udp_server = udprelay.UDPRelay(config, dns_resolver, True)
        loop = eventloop.EventLoop()
        dns_resolver.add_to_loop(loop)
        tcp_server.add_to_loop(loop)
        udp_server.add_to_loop(loop)

        def handler(signum, _):
            logging.warn('received SIGQUIT, doing graceful shutting down..')
            tcp_server.close(next_tick=True)
            udp_server.close(next_tick=True)

        signal.signal(getattr(signal, 'SIGQUIT', signal.SIGTERM), handler)

        def int_handler(signum, _):
            sys.exit(1)

        signal.signal(signal.SIGINT, int_handler)

        daemon.set_user(config.get('user', None))
        loop.run()
    except Exception as e:
        shell.print_exception(e)
        sys.exit(1)
Exemplo n.º 6
0
def main(dictionary=None, str_json=None, port=None):
    shell.check_python()

    # fix py2exe
    if str_json:
        config = shell.check_and_parse_config(
            shell.parse_json_in_str(shell.remove_comment(str_json)))
    elif dictionary:
        config = shell.check_and_parse_config(dictionary)
    else:
        raise Exception('No config specified')

    if port:
        config['local_port'] = int(port)

    if not config.get('dns_ipv6', False):
        asyncdns.IPV6_CONNECTION_SUPPORT = False

    daemon.daemon_exec(config)
    # logging.info("local start with protocol[%s] password [%s] method [%s] obfs [%s] obfs_param [%s]" %
    #         (config['protocol'], config['password'], config['method'], config['obfs'], config['obfs_param']))

    try:
        # logging.info("starting local at %s:%d" %
        #              (config['local_address'], config['local_port']))

        dns_resolver = asyncdns.DNSResolver()
        tcp_server = tcprelay.TCPRelay(config, dns_resolver, True)
        udp_server = udprelay.UDPRelay(config, dns_resolver, True)
        loop = eventloop.EventLoop()
        dns_resolver.add_to_loop(loop)
        tcp_server.add_to_loop(loop)
        udp_server.add_to_loop(loop)

        # daemon.set_user(config.get('user', None))
        return [loop, tcp_server, udp_server]
        loop.run()
    except OSError as e:
        print(e)
        raise OSError(e)
    except Exception as e:
        if 'tcp_server' in locals():
            tcp_server.close(next_tick=True)
        if 'udp_server' in locals():
            udp_server.close(next_tick=True)
        if 'loop' in locals():
            loop.stop()
        shell.print_exception(e)
        raise Exception(e)
Exemplo n.º 7
0
def main():
    shell.check_python()

    # fix py2exe
    if hasattr(sys, "frozen") and sys.frozen in \
            ("windows_exe", "console_exe"):
        p = os.path.dirname(os.path.abspath(sys.executable))
        os.chdir(p)

    config = shell.get_config(True)

    if not config.get('dns_ipv6', False):
        asyncdns.IPV6_CONNECTION_SUPPORT = False

    daemon.daemon_exec(config)
    logging.info("local start with protocol[%s] password [%s] method [%s] obfs [%s] obfs_param [%s]" %
            (config['protocol'], config['password'], config['method'], config['obfs'], config['obfs_param']))

    try:
        logging.info("starting local at %s:%d" %
                     (config['local_address'], config['local_port']))

        dns_resolver = asyncdns.DNSResolver()
        tcp_server = tcprelay.TCPRelay(config, dns_resolver, True)
        udp_server = udprelay.UDPRelay(config, dns_resolver, True)
        loop = eventloop.EventLoop()
        dns_resolver.add_to_loop(loop)
        tcp_server.add_to_loop(loop)
        udp_server.add_to_loop(loop)

        def handler(signum, _):
            logging.warn('received SIGQUIT, doing graceful shutting down..')
            tcp_server.close(next_tick=True)
            udp_server.close(next_tick=True)
        signal.signal(getattr(signal, 'SIGQUIT', signal.SIGTERM), handler)

        def int_handler(signum, _):
            sys.exit(1)
        signal.signal(signal.SIGINT, int_handler)

        daemon.set_user(config.get('user', None))
        loop.run()
    except Exception as e:
        shell.print_exception(e)
        sys.exit(1)
Exemplo n.º 8
0
def daemon_stop(pid_file):
    import errno
    try:
        with open(pid_file) as f:
            buf = f.read()
            pid = common.to_str(buf)
            if not buf:
                logging.error('not running')
    except IOError as e:
        shell.print_exception(e)
        if e.errno == errno.ENOENT:
            # always exit 0 if we are sure daemon is not running
            logging.error('not running')
            return
        sys.exit(1)
    pid = int(pid)
    if pid > 0:
        try:
            os.kill(pid, signal.SIGTERM)
        except OSError as e:
            if e.errno == errno.ESRCH:
                logging.error('not running')
                # always exit 0 if we are sure daemon is not running
                return
            shell.print_exception(e)
            sys.exit(1)
    else:
        logging.error('pid is not positive: %d', pid)

    # sleep for maximum 10s
    for i in range(0, 200):
        try:
            # query for the pid
            os.kill(pid, 0)
        except OSError as e:
            if e.errno == errno.ESRCH:
                break
        time.sleep(0.05)
    else:
        logging.error('timed out when stopping pid %d', pid)
        sys.exit(1)
    print('stopped')
    os.unlink(pid_file)
 def write_to_server_socket(self, data, addr):
     uncomplete = False
     retry = 0
     try:
         self._server_socket.sendto(data, addr)
         data = None
         while self._data_to_write_to_server_socket:
             data_buf = self._data_to_write_to_server_socket[0]
             retry = data_buf[1] + 1
             del self._data_to_write_to_server_socket[0]
             data, addr = data_buf[0]
             self._server_socket.sendto(data, addr)
     except (OSError, IOError) as e:
         error_no = eventloop.errno_from_exception(e)
         uncomplete = True
         if error_no in (errno.EWOULDBLOCK,):
             pass
         else:
             shell.print_exception(e)
             return False
Exemplo n.º 10
0
 def write_to_server_socket(self, data, addr):
     uncomplete = False
     retry = 0
     try:
         self._server_socket.sendto(data, addr)
         data = None
         while self._data_to_write_to_server_socket:
             data_buf = self._data_to_write_to_server_socket[0]
             retry = data_buf[1] + 1
             del self._data_to_write_to_server_socket[0]
             data, addr = data_buf[0]
             self._server_socket.sendto(data, addr)
     except (OSError, IOError) as e:
         error_no = eventloop.errno_from_exception(e)
         uncomplete = True
         if error_no in (errno.EWOULDBLOCK, ):
             pass
         else:
             shell.print_exception(e)
             return False
Exemplo n.º 11
0
    def run_server():
        def child_handler(signum, _):
            logging.warn('received SIGQUIT, doing graceful shutting down..')
            list(map(lambda s: s.close(next_tick=True),
                     tcp_servers + udp_servers))
        signal.signal(getattr(signal, 'SIGQUIT', signal.SIGTERM),
                      child_handler)

        def int_handler(signum, _):
            sys.exit(1)
        signal.signal(signal.SIGINT, int_handler)

        try:
            loop = eventloop.EventLoop()
            dns_resolver.add_to_loop(loop)
            list(map(lambda s: s.add_to_loop(loop), tcp_servers + udp_servers))

            daemon.set_user(config.get('user', None))
            loop.run()
        except Exception as e:
            shell.print_exception(e)
            sys.exit(1)
Exemplo n.º 12
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def daemon_start(pid_file, log_file):

    def handle_exit(signum, _):
        if signum == signal.SIGTERM:
            sys.exit(0)
        sys.exit(1)

    signal.signal(signal.SIGINT, handle_exit)
    signal.signal(signal.SIGTERM, handle_exit)

    # fork only once because we are sure parent will exit
    pid = os.fork()
    assert pid != -1

    if pid > 0:
        # parent waits for its child
        time.sleep(5)
        sys.exit(0)

    # child signals its parent to exit
    ppid = os.getppid()
    pid = os.getpid()
    if write_pid_file(pid_file, pid) != 0:
        os.kill(ppid, signal.SIGINT)
        sys.exit(1)

    os.setsid()
    signal.signal(signal.SIG_IGN, signal.SIGHUP)

    print('started')
    os.kill(ppid, signal.SIGTERM)

    sys.stdin.close()
    try:
        freopen(log_file, 'a', sys.stdout)
        freopen(log_file, 'a', sys.stderr)
    except IOError as e:
        shell.print_exception(e)
        sys.exit(1)
Exemplo n.º 13
0
def parse_response(data):
    try:
        if len(data) >= 12:
            header = parse_header(data)
            if not header:
                return None
            res_id, res_qr, res_tc, res_ra, res_rcode, res_qdcount, \
                res_ancount, res_nscount, res_arcount = header

            qds = []
            ans = []
            offset = 12
            for i in range(0, res_qdcount):
                l, r = parse_record(data, offset, True)
                offset += l
                if r:
                    qds.append(r)
            for i in range(0, res_ancount):
                l, r = parse_record(data, offset)
                offset += l
                if r:
                    ans.append(r)
            for i in range(0, res_nscount):
                l, r = parse_record(data, offset)
                offset += l
            for i in range(0, res_arcount):
                l, r = parse_record(data, offset)
                offset += l
            response = DNSResponse()
            if qds:
                response.hostname = qds[0][0]
            for an in qds:
                response.questions.append((an[1], an[2], an[3]))
            for an in ans:
                response.answers.append((an[1], an[2], an[3]))
            return response
    except Exception as e:
        shell.print_exception(e)
        return None
Exemplo n.º 14
0
    def run(self):
        events = []
        while not self._stopping:
            asap = False
            try:
                events = self.poll(TIMEOUT_PRECISION)
            except (OSError, IOError) as e:
                if errno_from_exception(e) in (errno.EPIPE, errno.EINTR):
                    # EPIPE: Happens when the client closes the connection
                    # EINTR: Happens when received a signal
                    # handles them as soon as possible
                    asap = True
                    logging.debug('poll:%s', e)
                else:
                    logging.error('poll:%s', e)
                    import traceback
                    traceback.print_exc()
                    continue

            handle = False
            for sock, fd, event in events:
                handler = self._fdmap.get(fd, None)
                if handler is not None:
                    handler = handler[1]
                    try:
                        handle = handler.handle_event(sock, fd,
                                                      event) or handle
                    except (OSError, IOError) as e:
                        shell.print_exception(e)
            now = time.time()
            if asap or now - self._last_time >= TIMEOUT_PRECISION:
                for callback in self._periodic_callbacks:
                    callback()
                self._last_time = now
            if events and not handle:
                time.sleep(0.001)
Exemplo n.º 15
0
def main():
    shell.check_python()

    config = shell.get_config(False)

    shell.log_shadowsocks_version()

    daemon.daemon_exec(config)

    try:
        import resource
        logging.info('current process RLIMIT_NOFILE resource: soft %d hard %d'  % resource.getrlimit(resource.RLIMIT_NOFILE))
    except ImportError:
        pass

    if config['port_password']:
        pass
    else:
        config['port_password'] = {}
        server_port = config['server_port']
        if type(server_port) == list:
            for a_server_port in server_port:
                config['port_password'][a_server_port] = config['password']
        else:
            config['port_password'][str(server_port)] = config['password']

    if not config.get('dns_ipv6', False):
        asyncdns.IPV6_CONNECTION_SUPPORT = False

    if config.get('manager_address', 0):
        logging.info('entering manager mode')
        manager.run(config)
        return

    tcp_servers = []
    udp_servers = []
    dns_resolver = asyncdns.DNSResolver()
    if int(config['workers']) > 1:
        stat_counter_dict = None
    else:
        stat_counter_dict = {}
    port_password = config['port_password']
    config_password = config.get('password', 'm')
    del config['port_password']
    for port, password_obfs in port_password.items():
        method = config["method"]
        protocol = config.get("protocol", 'origin')
        protocol_param = config.get("protocol_param", '')
        obfs = config.get("obfs", 'plain')
        obfs_param = config.get("obfs_param", '')
        bind = config.get("out_bind", '')
        bindv6 = config.get("out_bindv6", '')
        if type(password_obfs) == list:
            password = password_obfs[0]
            obfs = common.to_str(password_obfs[1])
            if len(password_obfs) > 2:
                protocol = common.to_str(password_obfs[2])
        elif type(password_obfs) == dict:
            password = password_obfs.get('password', config_password)
            method = common.to_str(password_obfs.get('method', method))
            protocol = common.to_str(password_obfs.get('protocol', protocol))
            protocol_param = common.to_str(password_obfs.get('protocol_param', protocol_param))
            obfs = common.to_str(password_obfs.get('obfs', obfs))
            obfs_param = common.to_str(password_obfs.get('obfs_param', obfs_param))
            bind = password_obfs.get('out_bind', bind)
            bindv6 = password_obfs.get('out_bindv6', bindv6)
        else:
            password = password_obfs
        a_config = config.copy()
        ipv6_ok = False
        logging.info("server start with protocol[%s] password [%s] method [%s] obfs [%s] obfs_param [%s]" %
                (protocol, password, method, obfs, obfs_param))
        if 'server_ipv6' in a_config:
            try:
                if len(a_config['server_ipv6']) > 2 and a_config['server_ipv6'][0] == "[" and a_config['server_ipv6'][-1] == "]":
                    a_config['server_ipv6'] = a_config['server_ipv6'][1:-1]
                a_config['server_port'] = int(port)
                a_config['password'] = password
                a_config['method'] = method
                a_config['protocol'] = protocol
                a_config['protocol_param'] = protocol_param
                a_config['obfs'] = obfs
                a_config['obfs_param'] = obfs_param
                a_config['out_bind'] = bind
                a_config['out_bindv6'] = bindv6
                a_config['server'] = a_config['server_ipv6']
                logging.info("starting server at [%s]:%d" %
                             (a_config['server'], int(port)))
                tcp_servers.append(tcprelay.TCPRelay(a_config, dns_resolver, False, stat_counter=stat_counter_dict))
                udp_servers.append(udprelay.UDPRelay(a_config, dns_resolver, False, stat_counter=stat_counter_dict))
                if a_config['server_ipv6'] == b"::":
                    ipv6_ok = True
            except Exception as e:
                shell.print_exception(e)

        try:
            a_config = config.copy()
            a_config['server_port'] = int(port)
            a_config['password'] = password
            a_config['method'] = method
            a_config['protocol'] = protocol
            a_config['protocol_param'] = protocol_param
            a_config['obfs'] = obfs
            a_config['obfs_param'] = obfs_param
            a_config['out_bind'] = bind
            a_config['out_bindv6'] = bindv6
            logging.info("starting server at %s:%d" %
                         (a_config['server'], int(port)))
            tcp_servers.append(tcprelay.TCPRelay(a_config, dns_resolver, False, stat_counter=stat_counter_dict))
            udp_servers.append(udprelay.UDPRelay(a_config, dns_resolver, False, stat_counter=stat_counter_dict))
        except Exception as e:
            if not ipv6_ok:
                shell.print_exception(e)

    def run_server():
        def child_handler(signum, _):
            logging.warn('received SIGQUIT, doing graceful shutting down..')
            list(map(lambda s: s.close(next_tick=True),
                     tcp_servers + udp_servers))
        signal.signal(getattr(signal, 'SIGQUIT', signal.SIGTERM),
                      child_handler)

        def int_handler(signum, _):
            sys.exit(1)
        signal.signal(signal.SIGINT, int_handler)

        try:
            loop = eventloop.EventLoop()
            dns_resolver.add_to_loop(loop)
            list(map(lambda s: s.add_to_loop(loop), tcp_servers + udp_servers))

            daemon.set_user(config.get('user', None))
            loop.run()
        except Exception as e:
            shell.print_exception(e)
            sys.exit(1)

    if int(config['workers']) > 1:
        if os.name == 'posix':
            children = []
            is_child = False
            for i in range(0, int(config['workers'])):
                r = os.fork()
                if r == 0:
                    logging.info('worker started')
                    is_child = True
                    run_server()
                    break
                else:
                    children.append(r)
            if not is_child:
                def handler(signum, _):
                    for pid in children:
                        try:
                            os.kill(pid, signum)
                            os.waitpid(pid, 0)
                        except OSError:  # child may already exited
                            pass
                    sys.exit()
                signal.signal(signal.SIGTERM, handler)
                signal.signal(signal.SIGQUIT, handler)
                signal.signal(signal.SIGINT, handler)

                # master
                for a_tcp_server in tcp_servers:
                    a_tcp_server.close()
                for a_udp_server in udp_servers:
                    a_udp_server.close()
                dns_resolver.close()

                for child in children:
                    os.waitpid(child, 0)
        else:
            logging.warn('worker is only available on Unix/Linux')
            run_server()
    else:
        run_server()
Exemplo n.º 16
0
    def _handle_server_dns_resolved(self, error, remote_addr, server_addr, params):
        if error:
            return
        data, r_addr, uid, header_length = params
        user_id = self._listen_port
        try:
            server_port = remote_addr[1]
            addrs = socket.getaddrinfo(server_addr, server_port, 0,
                                        socket.SOCK_DGRAM, socket.SOL_UDP)
            if not addrs: # drop
                return
            af, socktype, proto, canonname, sa = addrs[0]
            server_addr = sa[0]
            key = client_key(r_addr, af)
            client_pair = self._cache.get(key, None)
            if client_pair is None:
                client_pair = self._cache_dns_client.get(key, None)
            if client_pair is None:
                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
                if self._forbidden_portset:
                    if sa[1] in self._forbidden_portset:
                        logging.debug('Port %d is in forbidden list, reject' % sa[1])
                        # drop
                        return
                client = socket.socket(af, socktype, proto)
                client_uid = uid
                client.setblocking(False)
                self._socket_bind_addr(client, af)
                is_dns = False
                if len(data) > header_length + 13 and data[header_length + 4 : header_length + 12] == b"\x00\x01\x00\x00\x00\x00\x00\x00":
                    is_dns = True
                else:
                    pass
                if sa[1] == 53 and is_dns: #DNS
                    logging.debug("DNS query %s from %s:%d" % (common.to_str(sa[0]), r_addr[0], r_addr[1]))
                    self._cache_dns_client[key] = (client, uid)
                else:
                    self._cache[key] = (client, uid)
                self._client_fd_to_server_addr[client.fileno()] = (r_addr, af)

                self._sockets.add(client.fileno())
                self._eventloop.add(client, eventloop.POLL_IN, self)

                logging.debug('UDP port %5d sockets %d' % (self._listen_port, len(self._sockets)))

                if uid is not None:
                    user_id = struct.unpack('<I', client_uid)[0]
            else:
                client, client_uid = client_pair
            self._cache.clear(self._udp_cache_size)
            self._cache_dns_client.clear(16)

            if self._is_local:
                ref_iv = [encrypt.encrypt_new_iv(self._method)]
                self._protocol.obfs.server_info.iv = ref_iv[0]
                data = self._protocol.client_udp_pre_encrypt(data)
                #logging.debug("%s" % (binascii.hexlify(data),))
                data = encrypt.encrypt_all_iv(self._protocol.obfs.server_info.key, self._method, 1, data, ref_iv)
                if not data:
                    return
            else:
                data = data[header_length:]
            if not data:
                return
        except Exception as e:
            shell.print_exception(e)
            logging.error("exception from user %d" % (user_id,))

        try:
            client.sendto(data, (server_addr, server_port))
            self.add_transfer_u(client_uid, len(data))
            if client_pair is None: # new request
                addr, port = client.getsockname()[:2]
                common.connect_log('UDP data to %s(%s):%d from %s:%d by user %d' %
                        (common.to_str(remote_addr[0]), common.to_str(server_addr), server_port, addr, port, user_id))
        except IOError as e:
            err = eventloop.errno_from_exception(e)
            logging.warning('IOError sendto %s:%d by user %d' % (server_addr, server_port, user_id))
            if err in (errno.EINPROGRESS, errno.EAGAIN):
                pass
            else:
                shell.print_exception(e)
Exemplo n.º 17
0
    def _handle_server_dns_resolved(self, error, remote_addr, server_addr,
                                    params):
        if error:
            return
        data, r_addr, uid, header_length = params
        user_id = self._listen_port
        try:
            server_port = remote_addr[1]
            addrs = socket.getaddrinfo(server_addr, server_port, 0,
                                       socket.SOCK_DGRAM, socket.SOL_UDP)
            if not addrs:  # drop
                return
            af, socktype, proto, canonname, sa = addrs[0]
            server_addr = sa[0]
            key = client_key(r_addr, af)
            client_pair = self._cache.get(key, None)
            if client_pair is None:
                client_pair = self._cache_dns_client.get(key, None)
            if client_pair is None:
                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
                if self._forbidden_portset:
                    if sa[1] in self._forbidden_portset:
                        logging.debug('Port %d is in forbidden list, reject' %
                                      sa[1])
                        # drop
                        return
                client = socket.socket(af, socktype, proto)
                client_uid = uid
                client.setblocking(False)
                self._socket_bind_addr(client, af)
                is_dns = False
                if len(data) > header_length + 13 and data[
                        header_length + 4:header_length +
                        12] == b"\x00\x01\x00\x00\x00\x00\x00\x00":
                    is_dns = True
                else:
                    pass
                if sa[1] == 53 and is_dns:  #DNS
                    logging.debug("DNS query %s from %s:%d" %
                                  (common.to_str(sa[0]), r_addr[0], r_addr[1]))
                    self._cache_dns_client[key] = (client, uid)
                else:
                    self._cache[key] = (client, uid)
                self._client_fd_to_server_addr[client.fileno()] = (r_addr, af)

                self._sockets.add(client.fileno())
                self._eventloop.add(client, eventloop.POLL_IN, self)

                logging.debug('UDP port %5d sockets %d' %
                              (self._listen_port, len(self._sockets)))

                if uid is not None:
                    user_id = struct.unpack('<I', client_uid)[0]
            else:
                client, client_uid = client_pair
            self._cache.clear(self._udp_cache_size)
            self._cache_dns_client.clear(16)

            if self._is_local:
                ref_iv = [encrypt.encrypt_new_iv(self._method)]
                self._protocol.obfs.server_info.iv = ref_iv[0]
                data = self._protocol.client_udp_pre_encrypt(data)
                #logging.debug("%s" % (binascii.hexlify(data),))
                data = encrypt.encrypt_all_iv(
                    self._protocol.obfs.server_info.key, self._method, 1, data,
                    ref_iv)
                if not data:
                    return
            else:
                data = data[header_length:]
            if not data:
                return
        except Exception as e:
            shell.print_exception(e)
            logging.error("exception from user %d" % (user_id, ))

        try:
            client.sendto(data, (server_addr, server_port))
            self.add_transfer_u(client_uid, len(data))
            if client_pair is None:  # new request
                addr, port = client.getsockname()[:2]
                common.connect_log(
                    'UDP data to %s(%s):%d from %s:%d by user %d' %
                    (common.to_str(remote_addr[0]), common.to_str(server_addr),
                     server_port, addr, port, user_id))
        except IOError as e:
            err = eventloop.errno_from_exception(e)
            logging.warning('IOError sendto %s:%d by user %d' %
                            (server_addr, server_port, user_id))
            if err in (errno.EINPROGRESS, errno.EAGAIN):
                pass
            else:
                shell.print_exception(e)