Golang Buffer.SliceFrom方法代码示例

func (this *SimpleAuthenticator) Open(buffer *alloc.Buffer) bool {
	len := buffer.Len()
	xtra := 4 - len%4
	if xtra != 0 {
		buffer.Slice(0, len+xtra)
	}
	xorbkd(buffer.Value)
	if xtra != 0 {
		buffer.Slice(0, len)
	}

	fnvHash := fnv.New32a()
	fnvHash.Write(buffer.Value[4:])
	if serial.BytesToUint32(buffer.Value[:4]) != fnvHash.Sum32() {
		return false
	}

	length := serial.BytesToUint16(buffer.Value[4:6])
	if buffer.Len()-6 != int(length) {
		return false
	}

	buffer.SliceFrom(6)

	return true
}

// Write implements Writer.Write(). Write() takes ownership of the given buffer.
func (this *AdaptiveWriter) Write(buffer *alloc.Buffer) error {
	defer buffer.Release()
	for !buffer.IsEmpty() {
		nBytes, err := this.writer.Write(buffer.Value)
		if err != nil {
			return err
		}
		buffer.SliceFrom(nBytes)
	}
	return nil
}

func (this *SRTP) Open(payload *alloc.Buffer) bool {
	payload.SliceFrom(this.Overhead())
	return true
}

func (this *Server) handlerUDPPayload(payload *alloc.Buffer, session *proxy.SessionInfo) {
	defer payload.Release()

	source := session.Source
	ivLen := this.config.Cipher.IVSize()
	iv := payload.Value[:ivLen]
	key := this.config.Key
	payload.SliceFrom(ivLen)

	stream, err := this.config.Cipher.NewDecodingStream(key, iv)
	if err != nil {
		log.Error("Shadowsocks: Failed to create decoding stream: ", err)
		return
	}

	reader := crypto.NewCryptionReader(stream, payload)

	request, err := ReadRequest(reader, NewAuthenticator(HeaderKeyGenerator(key, iv)), true)
	if err != nil {
		if err != io.EOF {
			log.Access(source, "", log.AccessRejected, err)
			log.Warning("Shadowsocks: Invalid request from ", source, ": ", err)
		}
		return
	}
	//defer request.Release()

	dest := v2net.UDPDestination(request.Address, request.Port)
	log.Access(source, dest, log.AccessAccepted, "")
	log.Info("Shadowsocks: Tunnelling request to ", dest)

	this.udpServer.Dispatch(&proxy.SessionInfo{Source: source, Destination: dest}, request.DetachUDPPayload(), func(destination v2net.Destination, payload *alloc.Buffer) {
		defer payload.Release()

		response := alloc.NewBuffer().Slice(0, ivLen)
		defer response.Release()

		rand.Read(response.Value)
		respIv := response.Value

		stream, err := this.config.Cipher.NewEncodingStream(key, respIv)
		if err != nil {
			log.Error("Shadowsocks: Failed to create encoding stream: ", err)
			return
		}

		writer := crypto.NewCryptionWriter(stream, response)

		switch request.Address.Family() {
		case v2net.AddressFamilyIPv4:
			writer.Write([]byte{AddrTypeIPv4})
			writer.Write(request.Address.IP())
		case v2net.AddressFamilyIPv6:
			writer.Write([]byte{AddrTypeIPv6})
			writer.Write(request.Address.IP())
		case v2net.AddressFamilyDomain:
			writer.Write([]byte{AddrTypeDomain, byte(len(request.Address.Domain()))})
			writer.Write([]byte(request.Address.Domain()))
		}

		writer.Write(request.Port.Bytes(nil))
		writer.Write(payload.Value)

		if request.OTA {
			respAuth := NewAuthenticator(HeaderKeyGenerator(key, respIv))
			respAuth.Authenticate(response.Value, response.Value[ivLen:])
		}

		this.udpHub.WriteTo(response.Value, source)
	})
}

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

	ivLen := account.Cipher.IVSize()
	iv := payload.Value[:ivLen]
	payload.SliceFrom(ivLen)

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

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

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

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

		actualAuth := authenticator.Authenticate(nil, payload.Value[0:payloadLen])
		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.Value[:4])
		payload.SliceFrom(4)
	case AddrTypeIPv6:
		request.Address = v2net.IPAddress(payload.Value[:16])
		payload.SliceFrom(16)
	case AddrTypeDomain:
		domainLength := int(payload.Value[0])
		request.Address = v2net.DomainAddress(string(payload.Value[1 : 1+domainLength]))
		payload.SliceFrom(1 + domainLength)
	default:
		return nil, nil, errors.New("Shadowsocks|UDP: Unknown address type")
	}

	request.Port = v2net.PortFromBytes(payload.Value[:2])
	payload.SliceFrom(2)

	return request, payload, nil
}

func (this *AuthChunkReader) Read() (*alloc.Buffer, error) {
	var buffer *alloc.Buffer
	if this.last != nil {
		buffer = this.last
		this.last = nil
	} else {
		buffer = alloc.NewBufferWithSize(4096).Clear()
	}

	if this.chunkLength == -1 {
		for buffer.Len() < 6 {
			_, err := buffer.FillFrom(this.reader)
			if err != nil {
				buffer.Release()
				return nil, io.ErrUnexpectedEOF
			}
		}
		length := serial.BytesToUint16(buffer.Value[:2])
		this.chunkLength = int(length) - 4
		this.validator = NewValidator(serial.BytesToUint32(buffer.Value[2:6]))
		buffer.SliceFrom(6)
		if buffer.Len() < this.chunkLength && this.chunkLength <= 2048 {
			_, err := buffer.FillFrom(this.reader)
			if err != nil {
				buffer.Release()
				return nil, io.ErrUnexpectedEOF
			}
		}
	} else if buffer.Len() < this.chunkLength {
		_, err := buffer.FillFrom(this.reader)
		if err != nil {
			buffer.Release()
			return nil, io.ErrUnexpectedEOF
		}
	}

	if this.chunkLength == 0 {
		buffer.Release()
		return nil, io.EOF
	}

	if buffer.Len() < this.chunkLength {
		this.validator.Consume(buffer.Value)
		this.chunkLength -= buffer.Len()
	} else {
		this.validator.Consume(buffer.Value[:this.chunkLength])
		if !this.validator.Validate() {
			buffer.Release()
			return nil, transport.ErrCorruptedPacket
		}
		leftLength := buffer.Len() - this.chunkLength
		if leftLength > 0 {
			this.last = alloc.NewBufferWithSize(leftLength + 4096).Clear()
			this.last.Append(buffer.Value[this.chunkLength:])
			buffer.Slice(0, this.chunkLength)
		}

		this.chunkLength = -1
		this.validator = nil
	}

	return buffer, nil
}