Example #1
0
    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 = pack_addr(r_addr[0]) + struct.pack('>H', r_addr[1]) + data
            try:
                response = cryptor.encrypt_all(self._password, self._method,
                                               data, self._crypto_path)
            except Exception:
                logging.debug("UDP handle_client: encrypt data failed")
                return
            if not response:
                return
        else:
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method, data,
                                                    self._crypto_path)
            except Exception:
                logging.debug('UDP handle_client: decrypt data failed')
                return
            if not data:
                return
            header_result = parse_header(data)
            if header_result is None:
                return
            addrtype, dest_addr, dest_port, header_length = header_result
            if self._is_tunnel:
                # remove ss header
                response = data[header_length:]
            else:
                response = b'\x00\x00\x00' + data
        client_addr = self._client_fd_to_server_addr.get(sock.fileno())

        if self._stat_callback:
            activity = {
                'remote_address': client_addr,
                'local_address': r_addr[0],
                'protocal': 'UDP',
                'type': 'UP',
                'traffic': len(data),
                'time': datetime.datetime.today().strftime('%Y-%m-%d %H:%M:%S')
            }
            self._stat_callback(self._listen_port, activity)

        if client_addr:
            logging.debug("send udp response to %s:%d" %
                          (client_addr[0], client_addr[1]))
            self._server_socket.sendto(response, client_addr)
        else:
            # this packet is from somewhere else we know
            # simply drop that packet
            pass
Example #2
0
    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])
            # 域名规范:域名不能超过255个字符。其中顶级域名不能超过63字符
            if addrlen > 255:
                # drop
                return
            # pack_addr(r_addr[0]):把r_addr[0]打包成shadowvpn的专用的地址header,追加到r_addr[0]头部。
            # struct.pack('>H', r_addr[1]):打包成Big-Endian格式
            data = pack_addr(r_addr[0]) + struct.pack('>H', r_addr[1]) + data
            try:
                response = cryptor.encrypt_all(self._password,
                                               self._method, data,
                                               self._crypto_path)
            except Exception:
                logging.debug("UDP handle_client: encrypt data failed")
                return
            if not response:
                return
        # 本地端收到服务端发来的加密udp
        else:
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method, data,
                                                    self._crypto_path)
            except Exception:
                logging.debug('UDP handle_client: decrypt data failed')
                return
            if not data:
                return
            header_result = parse_header(data)
            if header_result is None:
                return
            addrtype, dest_addr, dest_port, header_length = header_result
            if self._is_tunnel:
                # remove ss header
                response = data[header_length:]
            else:
				# addrtype, dest_addr, dest_port, header_length = header_result
            	# 还原为标准的udp数据报格式,加上首3个字节
                response = b'\x00\x00\x00' + data
        client_addr = self._client_fd_to_server_addr.get(sock.fileno())
        if client_addr:
            logging.debug("send udp response to %s:%d"
                          % (client_addr[0], client_addr[1]))
            self._server_socket.sendto(response, client_addr)
        else:
            # this packet is from somewhere else we know
            # simply drop that packet
            pass
Example #3
0
 def _handle_client(self, sock):
     data, r_addr = sock.recvfrom(BUF_SIZE)
     if not data:
         logging.debug('U[%d] UDP handle_client: data is empty' %
                       self._config['server_port'])
         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
         try:
             response = cryptor.encrypt_all(self._password,
                                            self._method, data,
                                            self._crypto_path)
         except Exception:
             logging.debug("UDP handle_client: encrypt data failed")
             return
         if not response:
             return
     else:
         try:
             data, key, iv = cryptor.decrypt_all(self._password,
                                                 self._method, data,
                                                 self._crypto_path)
         except Exception:
             logging.debug('UDP handle_client: decrypt data failed')
             return
         if not data:
             return
         header_result = parse_header(data)
         if header_result is None:
             return
         addrtype, dest_addr, dest_port, header_length = header_result
         if self._is_tunnel:
             # remove ss header
             response = data[header_length:]
         else:
             response = b'\x00\x00\x00' + data
     client_addr = self._client_fd_to_server_addr.get(sock.fileno())
     if client_addr:
         logging.debug("send udp response to %s:%d"
                       % (client_addr[0], client_addr[1]))
         self._server_socket.sendto(response, client_addr)
     else:
         # this packet is from somewhere else we know
         # simply drop that packet
         pass
Example #4
0
 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
         try:
             response = cryptor.encrypt_all(self._password,
                                            self._method, data,
                                            self._crypto_path)
         except Exception:
             logging.debug("UDP handle_client: encrypt data failed")
             return
         if not response:
             return
     else:
         try:
             data, key, iv = cryptor.decrypt_all(self._password,
                                                 self._method, data,
                                                 self._crypto_path)
         except Exception:
             logging.debug('UDP handle_client: decrypt data failed')
             return
         if not data:
             return
         header_result = parse_header(data)
         if header_result is None:
             return
         addrtype, dest_addr, dest_port, header_length = header_result
         if self._is_tunnel:
             # remove ss header
             response = data[header_length:]
         else:
             response = b'\x00\x00\x00' + data
     client_addr = self._client_fd_to_server_addr.get(sock.fileno())
     if client_addr:
         logging.debug("send udp response to %s:%d"
                       % (client_addr[0], client_addr[1]))
         self._server_socket.sendto(response, client_addr)
     else:
         # this packet is from somewhere else we know
         # simply drop that packet
         pass
Example #5
0
    def _handle_server(self):
        server = self._server_socket
        data, r_addr = server.recvfrom(BUF_SIZE)
        key = None
        iv = None
        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:
            if self._is_tunnel:
                # add ss header to data
                tunnel_remote = self.tunnel_remote
                tunnel_remote_port = self.tunnel_remote_port
                data = common.add_header(tunnel_remote, tunnel_remote_port,
                                         data)
            else:
                frag = common.ord(data[2])
                if frag != 0:
                    logging.warn('UDP drop a message since frag is not 0')
                    return
                else:
                    data = data[3:]
        else:
            # decrypt data
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method, data,
                                                    self._crypto_path)
            except Exception:
                logging.debug('UDP handle_server: decrypt data failed')
                return
            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
        logging.info("[%d] udp data to %s:%d from %s:%d" %
                     (self._config['server_port'], dest_addr, dest_port,
                      r_addr[0], r_addr[1]))
        if self._is_local:
            server_addr, server_port = self._get_a_server()
        else:
            server_addr, server_port = dest_addr, dest_port
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            self._ota_enable_session = addrtype & ADDRTYPE_AUTH
            if self._ota_enable and not self._ota_enable_session:
                logging.warn('client one time auth is required')
                return
            if self._ota_enable_session:
                if len(data) < header_length + ONETIMEAUTH_BYTES:
                    logging.warn('UDP one time auth header is too short')
                    return
                _hash = data[-ONETIMEAUTH_BYTES:]
                data = data[:-ONETIMEAUTH_BYTES]
                _key = iv + key
                if onetimeauth_verify(_hash, data, _key) is False:
                    logging.warn('UDP one time auth fail')
                    return
        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:
            key, iv, m = cryptor.gen_key_iv(self._password, self._method)
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            if self._ota_enable_session:
                data = self._ota_chunk_data_gen(key, iv, data)
            try:
                data = cryptor.encrypt_all_m(key, iv, m, self._method, data,
                                             self._crypto_path)
            except Exception:
                logging.debug("UDP handle_server: encrypt data failed")
                return
            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)
Example #6
0
    def _handle_server(self):
        server = self._server_socket
        data, r_addr = server.recvfrom(BUF_SIZE)
        key = None
        iv = None
        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:
            if self._is_tunnel:
                # add ss header to data
                tunnel_remote = self.tunnel_remote
                tunnel_remote_port = self.tunnel_remote_port
                data = common.add_header(tunnel_remote,
                                         tunnel_remote_port, data)
            else:
                frag = common.ord(data[2])
                if frag != 0:
                    logging.warn('UDP drop a message since frag is not 0')
                    return
                else:
                    data = data[3:]
        else:
            # decrypt data
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method,
                                                    data, self._crypto_path)
            except Exception:
                logging.debug('UDP handle_server: decrypt data failed')
                return
            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
        logging.info("udp data to %s:%d from %s:%d"
                     % (dest_addr, dest_port, r_addr[0], r_addr[1]))
        if self._is_local:
            server_addr, server_port = self._get_a_server()
        else:
            server_addr, server_port = dest_addr, dest_port
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            self._ota_enable_session = addrtype & ADDRTYPE_AUTH
            if self._ota_enable and not self._ota_enable_session:
                logging.warn('client one time auth is required')
                return
            if self._ota_enable_session:
                if len(data) < header_length + ONETIMEAUTH_BYTES:
                    logging.warn('UDP one time auth header is too short')
                    return
                _hash = data[-ONETIMEAUTH_BYTES:]
                data = data[: -ONETIMEAUTH_BYTES]
                _key = iv + key
                if onetimeauth_verify(_hash, data, _key) is False:
                    logging.warn('UDP one time auth fail')
                    return
        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:
            key, iv, m = cryptor.gen_key_iv(self._password, self._method)
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            if self._ota_enable_session:
                data = self._ota_chunk_data_gen(key, iv, data)
            try:
                data = cryptor.encrypt_all_m(key, iv, m, self._method, data,
                                             self._crypto_path)
            except Exception:
                logging.debug("UDP handle_server: encrypt data failed")
                return
            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)
Example #7
0
    def _handle_server(self):
        server = self._server_socket
        data, r_addr = server.recvfrom(BUF_SIZE)
        client_address = r_addr[0]
        key = None
        iv = None
        if not data:
            logging.debug('U[%d] UDP handle_server: data is empty' %
                          self._config['server_port'])
        if self._stat_callback:
            self._stat_callback(self._listen_port, len(data))
        if self._is_local:
            if self._is_tunnel:
                # add ss header to data
                tunnel_remote = self.tunnel_remote
                tunnel_remote_port = self.tunnel_remote_port
                data = common.add_header(tunnel_remote,
                                         tunnel_remote_port, data)
            else:
                frag = common.ord(data[2])
                if frag != 0:
                    logging.warning('UDP drop a message since frag is not 0')
                    return
                else:
                    data = data[3:]
        else:
            # decrypt data
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method,
                                                    data)
            except Exception:
                logging.debug('U[%d] UDP handle_server: decrypt data failed' % self._config[
                    'server_port'])
                return
            if not data:
                logging.debug(
                    'U[%d] UDP handle_server: data is empty after decrypt' % self._config[
                        'server_port']
                )
                return
        header_result = parse_header(data)
        if header_result is None:
            return
        addrtype, dest_addr, dest_port, header_length = header_result

        if self._config['firewall_ports'] and self._config['server_port'] not in self._config['firewall_trusted']:
            # Firewall enabled
            if self._config['firewall_mode'] == 'blacklist' and dest_port in self._config['firewall_ports']:
                firewall_blocked = True
            elif self._config['firewall_mode'] == 'whitelist' and dest_port not in self._config['firewall_ports']:
                firewall_blocked = True
            else:
                firewall_blocked = False
        else:
            firewall_blocked = False
        if firewall_blocked:
            logging.warning('U[%d] UDP PORT BANNED: RP[%d] A[%s-->%s]' % (
                self._config['server_port'], dest_port,
                client_address, common.to_str(dest_addr)
            ))
            return
        else:
            logging.info('U[%d] UDP CONN: RP[%d] A[%s-->%s]' % (
                self._config['server_port'], dest_port,
                client_address, common.to_str(dest_addr)
            ))
        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('U[%d] IP %s is in forbidden list, drop' %
                                  (self._config['server_port'], 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:
            key, iv, m = cryptor.gen_key_iv(self._password, self._method)
            try:
                data = cryptor.encrypt_all_m(key, iv, m, self._method, data,
                                             self._crypto_path)
            except Exception:
                logging.debug("UDP handle_server: encrypt data failed")
                return
            if not data:
                return
        else:
            data = data[header_length:]
        if not data:
            return
        try:
            client.sendto(data, (server_addr, server_port))
        except (socket.error, OSError, IOError) as e:
            error_no = eventloop.errno_from_exception(e)
            if sys.platform == "win32":
                if error_no in (errno.EAGAIN, errno.EINPROGRESS,
                                errno.EWOULDBLOCK, errno.WSAEWOULDBLOCK):
                    pass
                else:
                    shell.print_exception(e)
            elif error_no in (errno.EAGAIN, errno.EINPROGRESS,
                              errno.EWOULDBLOCK):
                pass
            else:
                shell.print_exception(e)
Example #8
0
    def _handle_server(self):
        server = self._server_socket

        data, r_addr = server.recvfrom(BUF_SIZE)
        key = None
        iv = None
        if not data:
            logging.debug('UDP handle_server: data is empty')
        if self._stat_callback:
            self._stat_callback(self._listen_port, len(data))
		
		# 若本地端从监听1080端口收到本机应用进程(例如chrome)的数据,进行切除header
        if self._is_local:
            if self._is_tunnel:
                # add ss header to data
                tunnel_remote = self.tunnel_remote
                tunnel_remote_port = self.tunnel_remote_port
                data = common.add_header(tunnel_remote,
                                         tunnel_remote_port, data)
            else:
                frag = common.ord(data[2])
                if frag != 0:
                    logging.warn('UDP drop a message since frag is not 0')
                    return
                else:
                    data = data[3:]
		# 如果是服务端收到本地端发出的udp数据,先进行解密
        else:
            # decrypt data
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method,
                                                    data, self._crypto_path)
            except Exception:
                logging.debug('UDP handle_server: decrypt data failed')
                return
            if not data:
                logging.debug('UDP handle_server: data is empty after decrypt')
                return
        # 处理header
        header_result = parse_header(data)
        if header_result is None:
            return
        addrtype, dest_addr, dest_port, header_length = header_result
        logging.info("udp data to %s:%d from %s:%d"
                     % (dest_addr, dest_port, r_addr[0], r_addr[1]))
        if self._is_local:
            # 如果是local收到,则server_addr server_port都是远程的
            server_addr, server_port = self._get_a_server()
        else:
            # 如果远程收到,则将server_addr这些改成dest_addr dest_port,方便操作
            # dest就是最终目标,例如 www.youtube.com:443
            server_addr, server_port = dest_addr, dest_port
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            self._ota_enable_session = addrtype & ADDRTYPE_AUTH
            if self._ota_enable and not self._ota_enable_session:
                logging.warn('client one time auth is required')
                return
            if self._ota_enable_session:
                if len(data) < header_length + ONETIMEAUTH_BYTES:
                    logging.warn('UDP one time auth header is too short')
                    return
                _hash = data[-ONETIMEAUTH_BYTES:]
                data = data[: -ONETIMEAUTH_BYTES]
                _key = iv + key
                if onetimeauth_verify(_hash, data, _key) is False:
                    logging.warn('UDP one time auth fail')
                    return
        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())
            # 添加进Eventloop,标志设置为可读
            self._eventloop.add(client, eventloop.POLL_IN, self)

        # 如果是local,要向远程发,要过墙,所以要加密
        if self._is_local:
            key, iv, m = cryptor.gen_key_iv(self._password, self._method)
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            if self._ota_enable_session:
                data = self._ota_chunk_data_gen(key, iv, data)
            try:
                data = cryptor.encrypt_all_m(key, iv, m, self._method, data,
                                             self._crypto_path)
            except Exception:
                logging.debug("UDP handle_server: encrypt data failed")
                return
            if not data:
                return
        # 如果是远程,要向dest发请求,所以把除数据的部分除去,即除去header。
        else:
            # data已经在上面进行数据解密了。不需要像local一样加密发送。
            # data已经被切除头的3个字节了
            data = data[header_length:]
        if not data:
            return
        try:
            # 发送,完美无瑕。。。。
            # 这个sendto同时有udp的和tcp的两种,sendto函数主要用于UDP,但这里两种都用了
            # 调用sendto时候会自动加上那个首3个字节,貌似是x00 x00 x00
            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)
Example #9
0
    def _handle_server(self):
        server = self._server_socket
        data, r_addr = server.recvfrom(BUF_SIZE)
        client_address = r_addr[0]
        key = None
        iv = None
        if not data:
            logging.debug('U[%d] UDP handle_server: data is empty' %
                          self._config['server_port'])
        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('U[%d] UDP drop a message since frag is not 0' %
                             self._config['server_port'])
                return
            else:
                data = data[3:]
        else:
            # decrypt data
            try:
                data, key, iv = cryptor.decrypt_all(self._password,
                                                    self._method, data)
            except Exception:
                logging.debug('U[%d] UDP handle_server: decrypt data failed' %
                              self._config['server_port'])
                return
            if not data:
                logging.debug(
                    'U[%d] UDP handle_server: data is empty after decrypt' %
                    self._config['server_port'])
                return
        header_result = parse_header(data)
        if header_result is None:
            return
        addrtype, dest_addr, dest_port, header_length = header_result

        if self._config['firewall_ports'] and self._config[
                'server_port'] not in self._config['firewall_trusted']:
            # Firewall enabled
            if self._config[
                    'firewall_mode'] == 'blacklist' and dest_port in self._config[
                        'firewall_ports']:
                firewall_blocked = True
            elif self._config[
                    'firewall_mode'] == 'whitelist' and dest_port not in self._config[
                        'firewall_ports']:
                firewall_blocked = True
            else:
                firewall_blocked = False
        else:
            firewall_blocked = False
        if firewall_blocked:
            logging.warning('U[%d] UDP PORT BANNED: RP[%d] A[%s-->%s]' %
                            (self._config['server_port'], dest_port,
                             client_address, common.to_str(dest_addr)))
            return
        else:
            logging.info('U[%d] UDP CONN: RP[%d] A[%s-->%s]' %
                         (self._config['server_port'], dest_port,
                          client_address, common.to_str(dest_addr)))
        if self._is_local:
            server_addr, server_port = self._get_a_server()
        else:
            server_addr, server_port = dest_addr, dest_port
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            if self._one_time_auth_enable or (addrtype & ADDRTYPE_AUTH
                                              == ADDRTYPE_AUTH):
                if not self._one_time_auth_enable and self._config['verbose']:
                    logging.info(
                        'U[%d] UDP one time auth automatically enabled' %
                        self._config['server_port'])
                self._one_time_auth_enable = True
                if len(data) < header_length + ONETIMEAUTH_BYTES:
                    logging.warn(
                        'U[%d] UDP one time auth header is too short' %
                        self._config['server_port'])
                    return
                _hash = data[-ONETIMEAUTH_BYTES:]
                data = data[:-ONETIMEAUTH_BYTES]
                _key = iv + key
                if onetimeauth_verify(_hash, data, _key) is False:
                    logging.warn('U[%d] UDP one time auth fail' %
                                 self._config['server_port'])
                    return
        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(
                        'U[%d] IP %s is in forbidden list, drop' %
                        (self._config['server_port'], 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:
            key, iv, m = cryptor.gen_key_iv(self._password, self._method)
            # spec https://shadowsocks.org/en/spec/one-time-auth.html
            if self._one_time_auth_enable:
                data = self._ota_chunk_data_gen(key, iv, data)
            try:
                data = cryptor.encrypt_all_m(key, iv, m, self._method, data)
            except Exception:
                logging.debug("UDP handle_server: encrypt data failed")
                return
            if not data:
                return
        else:
            data = data[header_length:]
        if not data:
            return
        try:
            client.sendto(data, (server_addr, server_port))
        except (socket.error, OSError, IOError) as e:
            error_no = eventloop.errno_from_exception(e)
            if sys.platform == "win32":
                if error_no in (errno.EAGAIN, errno.EINPROGRESS,
                                errno.EWOULDBLOCK, errno.WSAEWOULDBLOCK):
                    pass
                else:
                    shell.print_exception(e)
            elif error_no in (errno.EAGAIN, errno.EINPROGRESS,
                              errno.EWOULDBLOCK):
                pass
            else:
                shell.print_exception(e)