Golang Buffer.Len方法代码示例

func (v *ChunkWriter) Write(payload *buf.Buffer) error {
	totalLength := payload.Len()
	serial.Uint16ToBytes(uint16(totalLength), v.buffer[:0])
	v.auth.Authenticate(payload.Bytes())(v.buffer[2:])
	copy(v.buffer[2+AuthSize:], payload.Bytes())
	_, err := v.writer.Write(v.buffer[:2+AuthSize+payload.Len()])
	return err
}

func (v *Server) handleUDPPayload(payload *buf.Buffer, session *proxy.SessionInfo) {
	source := session.Source
	log.Info("Socks: Client UDP connection from ", source)
	request, err := protocol.ReadUDPRequest(payload.Bytes())
	payload.Release()

	if err != nil {
		log.Error("Socks: Failed to parse UDP request: ", err)
		return
	}
	if request.Data.Len() == 0 {
		request.Data.Release()
		return
	}
	if request.Fragment != 0 {
		log.Warning("Socks: Dropping fragmented UDP packets.")
		// TODO handle fragments
		request.Data.Release()
		return
	}

	log.Info("Socks: Send packet to ", request.Destination(), " with ", request.Data.Len(), " bytes")
	log.Access(source, request.Destination, log.AccessAccepted, "")
	v.udpServer.Dispatch(&proxy.SessionInfo{Source: source, Destination: request.Destination(), Inbound: v.meta}, request.Data, func(destination v2net.Destination, payload *buf.Buffer) {
		response := &protocol.Socks5UDPRequest{
			Fragment: 0,
			Address:  request.Destination().Address,
			Port:     request.Destination().Port,
			Data:     payload,
		}
		log.Info("Socks: Writing back UDP response with ", payload.Len(), " bytes to ", destination)

		udpMessage := buf.NewLocal(2048)
		response.Write(udpMessage)

		v.udpMutex.RLock()
		if !v.accepting {
			v.udpMutex.RUnlock()
			return
		}
		nBytes, err := v.udpHub.WriteTo(udpMessage.Bytes(), destination)
		v.udpMutex.RUnlock()
		udpMessage.Release()
		response.Data.Release()
		if err != nil {
			log.Error("Socks: failed to write UDP message (", nBytes, " bytes) to ", destination, ": ", err)
		}
	})
}

func DecodeUDPPacket(user *protocol.User, payload *buf.Buffer) (*protocol.RequestHeader, *buf.Buffer, error) {
	rawAccount, err := user.GetTypedAccount()
	if err != nil {
		return nil, nil, errors.Base(err).Message("Shadowsocks|UDP: Failed to parse account.")
	}
	account := rawAccount.(*ShadowsocksAccount)

	ivLen := account.Cipher.IVSize()
	iv := payload.BytesTo(ivLen)
	payload.SliceFrom(ivLen)

	stream, err := account.Cipher.NewDecodingStream(account.Key, iv)
	if err != nil {
		return nil, nil, errors.Base(err).Message("Shadowsocks|UDP: Failed to initialize decoding stream.")
	}
	stream.XORKeyStream(payload.Bytes(), payload.Bytes())

	authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv))
	request := &protocol.RequestHeader{
		Version: Version,
		User:    user,
		Command: protocol.RequestCommandUDP,
	}

	addrType := (payload.Byte(0) & 0x0F)
	if (payload.Byte(0) & 0x10) == 0x10 {
		request.Option |= RequestOptionOneTimeAuth
	}

	if request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Disabled {
		return nil, nil, errors.New("Shadowsocks|UDP: Rejecting packet with OTA enabled, while server disables OTA.")
	}

	if !request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Enabled {
		return nil, nil, errors.New("Shadowsocks|UDP: Rejecting packet with OTA disabled, while server enables OTA.")
	}

	if request.Option.Has(RequestOptionOneTimeAuth) {
		payloadLen := payload.Len() - AuthSize
		authBytes := payload.BytesFrom(payloadLen)

		actualAuth := make([]byte, AuthSize)
		authenticator.Authenticate(payload.BytesTo(payloadLen))(actualAuth)
		if !bytes.Equal(actualAuth, authBytes) {
			return nil, nil, errors.New("Shadowsocks|UDP: Invalid OTA.")
		}

		payload.Slice(0, payloadLen)
	}

	payload.SliceFrom(1)

	switch addrType {
	case AddrTypeIPv4:
		request.Address = v2net.IPAddress(payload.BytesTo(4))
		payload.SliceFrom(4)
	case AddrTypeIPv6:
		request.Address = v2net.IPAddress(payload.BytesTo(16))
		payload.SliceFrom(16)
	case AddrTypeDomain:
		domainLength := int(payload.Byte(0))
		request.Address = v2net.DomainAddress(string(payload.BytesRange(1, 1+domainLength)))
		payload.SliceFrom(1 + domainLength)
	default:
		return nil, nil, errors.New("Shadowsocks|UDP: Unknown address type: ", addrType)
	}

	request.Port = v2net.PortFromBytes(payload.BytesTo(2))
	payload.SliceFrom(2)

	return request, payload, nil
}

func (v *Listener) OnReceive(payload *buf.Buffer, src v2net.Destination, originalDest v2net.Destination) {
	defer payload.Release()

	segments := v.reader.Read(payload.Bytes())
	if len(segments) == 0 {
		log.Info("KCP|Listener: discarding invalid payload from ", src)
		return
	}

	if !v.running {
		return
	}
	v.Lock()
	defer v.Unlock()
	if !v.running {
		return
	}
	if payload.Len() < 4 {
		return
	}
	conv := segments[0].Conversation()
	cmd := segments[0].Command()

	id := ConnectionID{
		Remote: src.Address,
		Port:   src.Port,
		Conv:   conv,
	}
	conn, found := v.sessions[id]

	if !found {
		if cmd == CommandTerminate {
			return
		}
		writer := &Writer{
			id:       id,
			hub:      v.hub,
			dest:     src,
			listener: v,
		}
		remoteAddr := &net.UDPAddr{
			IP:   src.Address.IP(),
			Port: int(src.Port),
		}
		localAddr := v.hub.Addr()
		sConn := &ServerConnection{
			id:     internal.NewConnectionID(v2net.LocalHostIP, src),
			local:  localAddr,
			remote: remoteAddr,
			writer: &KCPPacketWriter{
				Header:   v.header,
				Writer:   writer,
				Security: v.security,
			},
			closer: writer,
		}
		conn = NewConnection(conv, sConn, v, v.config)
		select {
		case v.awaitingConns <- conn:
		case <-time.After(time.Second * 5):
			conn.Close()
			return
		}
		v.sessions[id] = conn
	}
	conn.Input(segments)
}