func (this *VMessOutboundHandler) Dispatch(firstPacket v2net.Packet, ray ray.OutboundRay) error {
	vNextAddress, vNextUser := this.receiverManager.PickReceiver()

	command := protocol.CmdTCP
	if firstPacket.Destination().IsUDP() {
		command = protocol.CmdUDP
	}
	request := &protocol.VMessRequest{
		Version: protocol.Version,
		User:    vNextUser,
		Command: command,
		Address: firstPacket.Destination().Address(),
		Port:    firstPacket.Destination().Port(),
	}
	if command == protocol.CmdUDP {
		request.Option |= protocol.OptionChunk
	}

	buffer := alloc.NewSmallBuffer()
	defer buffer.Release()                      // Buffer is released after communication finishes.
	io.ReadFull(rand.Reader, buffer.Value[:33]) // 16 + 16 + 1
	request.RequestIV = buffer.Value[:16]
	request.RequestKey = buffer.Value[16:32]
	request.ResponseHeader = buffer.Value[32]

	return this.startCommunicate(request, vNextAddress, ray, firstPacket)
}

func (this *OutboundConnectionHandler) Dispatch(packet v2net.Packet, ray ray.OutboundRay) error {
	input := ray.OutboundInput()
	output := ray.OutboundOutput()

	this.Destination = packet.Destination()
	if packet.Chunk() != nil {
		this.ConnOutput.Write(packet.Chunk().Value)
		packet.Chunk().Release()
	}

	if packet.MoreChunks() {
		writeFinish := &sync.Mutex{}

		writeFinish.Lock()

		go func() {
			v2io.ChanToRawWriter(this.ConnOutput, input)
			writeFinish.Unlock()
		}()

		writeFinish.Lock()
	}

	v2io.RawReaderToChan(output, this.ConnInput)
	close(output)

	return nil
}

func (this *UDPServer) locateExistingAndDispatch(dest string, packet v2net.Packet) bool {
	this.RLock()
	defer this.RUnlock()
	if entry, found := this.conns[dest]; found {
		entry.inboundRay.InboundInput() <- packet.Chunk()
		return true
	}
	return false
}

func (this *BlackHole) Dispatch(firstPacket v2net.Packet, ray ray.OutboundRay) error {
	if chunk := firstPacket.Chunk(); chunk != nil {
		chunk.Release()
	}

	close(ray.OutboundOutput())
	if firstPacket.MoreChunks() {
		v2net.ChanToWriter(ioutil.Discard, ray.OutboundInput())
	}
	return nil
}

func (this *VMessOutboundHandler) handleRequest(conn net.Conn, request *protocol.VMessRequest, firstPacket v2net.Packet, input <-chan *alloc.Buffer, finish *sync.Mutex) {
	defer finish.Unlock()
	aesStream, err := v2crypto.NewAesEncryptionStream(request.RequestKey[:], request.RequestIV[:])
	if err != nil {
		log.Error("VMessOut: Failed to create AES encryption stream: ", err)
		return
	}
	encryptRequestWriter := v2crypto.NewCryptionWriter(aesStream, conn)

	buffer := alloc.NewBuffer().Clear()
	defer buffer.Release()
	buffer, err = request.ToBytes(protocol.NewRandomTimestampGenerator(protocol.Timestamp(time.Now().Unix()), 30), buffer)
	if err != nil {
		log.Error("VMessOut: Failed to serialize VMess request: ", err)
		return
	}

	// Send first packet of payload together with request, in favor of small requests.
	firstChunk := firstPacket.Chunk()
	moreChunks := firstPacket.MoreChunks()

	for firstChunk == nil && moreChunks {
		firstChunk, moreChunks = <-input
	}

	if firstChunk == nil && !moreChunks {
		log.Warning("VMessOut: Nothing to send. Existing...")
		return
	}

	if request.IsChunkStream() {
		vmessio.Authenticate(firstChunk)
	}

	aesStream.XORKeyStream(firstChunk.Value, firstChunk.Value)
	buffer.Append(firstChunk.Value)
	firstChunk.Release()

	_, err = conn.Write(buffer.Value)
	if err != nil {
		log.Error("VMessOut: Failed to write VMess request: ", err)
		return
	}

	if moreChunks {
		var streamWriter v2io.Writer
		streamWriter = v2io.NewAdaptiveWriter(encryptRequestWriter)
		if request.IsChunkStream() {
			streamWriter = vmessio.NewAuthChunkWriter(streamWriter)
		}
		v2io.ChanToWriter(streamWriter, input)
	}
	return
}

func (this *UDPServer) Dispatch(source v2net.Destination, packet v2net.Packet, callback UDPResponseCallback) {
	destString := source.String() + "-" + packet.Destination().String()
	if this.locateExistingAndDispatch(destString, packet) {
		return
	}

	this.Lock()
	inboundRay := this.packetDispatcher.DispatchToOutbound(v2net.NewPacket(packet.Destination(), packet.Chunk(), true))
	this.conns[destString] = &connEntry{
		inboundRay: inboundRay,
		callback:   callback,
	}
	this.Unlock()
	go this.handleConnection(destString, inboundRay, source, callback)
}

// Dispatches a Packet to an OutboundConnection.
// The packet will be passed through the router (if configured), and then sent to an outbound
// connection with matching tag.
func (this *Point) DispatchToOutbound(context app.Context, packet v2net.Packet) ray.InboundRay {
	direct := ray.NewRay()
	dest := packet.Destination()

	dispatcher := this.och

	if this.router != nil {
		if tag, err := this.router.TakeDetour(dest); err == nil {
			if handler, found := this.odh[tag]; found {
				dispatcher = handler
			}
		}
	}

	go this.FilterPacketAndDispatch(packet, direct, dispatcher)
	return direct
}

func handleRequest(conn net.Conn, request *protocol.VMessRequest, firstPacket v2net.Packet, input <-chan *alloc.Buffer, finish *sync.Mutex) {
	defer finish.Unlock()
	aesStream, err := v2crypto.NewAesEncryptionStream(request.RequestKey[:], request.RequestIV[:])
	if err != nil {
		log.Error("VMessOut: Failed to create AES encryption stream: %v", err)
		return
	}
	encryptRequestWriter := v2crypto.NewCryptionWriter(aesStream, conn)

	buffer := alloc.NewBuffer().Clear()
	defer buffer.Release()
	buffer, err = request.ToBytes(user.NewTimeHash(user.HMACHash{}), user.GenerateRandomInt64InRange, buffer)
	if err != nil {
		log.Error("VMessOut: Failed to serialize VMess request: %v", err)
		return
	}

	// Send first packet of payload together with request, in favor of small requests.
	firstChunk := firstPacket.Chunk()
	moreChunks := firstPacket.MoreChunks()

	for firstChunk == nil && moreChunks {
		firstChunk, moreChunks = <-input
	}

	if firstChunk == nil && !moreChunks {
		log.Warning("VMessOut: Nothing to send. Existing...")
		return
	}

	aesStream.XORKeyStream(firstChunk.Value, firstChunk.Value)
	buffer.Append(firstChunk.Value)
	firstChunk.Release()

	_, err = conn.Write(buffer.Value)
	if err != nil {
		log.Error("VMessOut: Failed to write VMess request: %v", err)
		return
	}

	if moreChunks {
		v2net.ChanToWriter(encryptRequestWriter, input)
	}
	return
}

func (this *Point) DispatchToOutbound(packet v2net.Packet) ray.InboundRay {
	direct := ray.NewRay()
	dest := packet.Destination()

	if this.router != nil {
		tag, err := this.router.TakeDetour(dest)
		if err == nil {
			handler, found := this.odh[tag]
			if found {
				go handler.Dispatch(packet, direct)
				return direct
			}
		}
	}

	go this.och.Dispatch(packet, direct)
	return direct
}

func handleRequest(conn net.Conn, request *protocol.VMessRequest, firstPacket v2net.Packet, input <-chan *alloc.Buffer, finish *sync.Mutex) {
	defer finish.Unlock()
	encryptRequestWriter, err := v2io.NewAesEncryptWriter(request.RequestKey[:], request.RequestIV[:], conn)
	if err != nil {
		log.Error("VMessOut: Failed to create encrypt writer: %v", err)
		return
	}

	buffer := alloc.NewBuffer()
	buffer.Clear()
	requestBytes, err := request.ToBytes(user.NewTimeHash(user.HMACHash{}), user.GenerateRandomInt64InRange, buffer.Value)
	if err != nil {
		log.Error("VMessOut: Failed to serialize VMess request: %v", err)
		return
	}

	// Send first packet of payload together with request, in favor of small requests.
	firstChunk := firstPacket.Chunk()
	moreChunks := firstPacket.MoreChunks()

	if firstChunk == nil && moreChunks {
		firstChunk, moreChunks = <-input
	}

	if firstChunk != nil {
		encryptRequestWriter.Crypt(firstChunk.Value)
		requestBytes = append(requestBytes, firstChunk.Value...)
		firstChunk.Release()

		_, err = conn.Write(requestBytes)
		buffer.Release()
		if err != nil {
			log.Error("VMessOut: Failed to write VMess request: %v", err)
			return
		}
	}

	if moreChunks {
		v2net.ChanToWriter(encryptRequestWriter, input)
	}
	return
}

// Dispatches a Packet to an OutboundConnection.
// The packet will be passed through the router (if configured), and then sent to an outbound
// connection with matching tag.
func (this *Point) DispatchToOutbound(context app.Context, packet v2net.Packet) ray.InboundRay {
	direct := ray.NewRay()
	dest := packet.Destination()

	dispatcher := this.och

	if this.router != nil {
		if tag, err := this.router.TakeDetour(dest); err == nil {
			if handler, found := this.odh[tag]; found {
				log.Info("Point: Taking detour [", tag, "] for [", dest, "]", tag, dest)
				dispatcher = handler
			} else {
				log.Warning("Point: Unable to find routing destination: ", tag)
			}
		}
	}

	go this.FilterPacketAndDispatch(packet, direct, dispatcher)
	return direct
}

func (this *VMessOutboundHandler) Dispatch(firstPacket v2net.Packet, ray ray.OutboundRay) error {
	vNextAddress, vNextUser := this.receiverManager.PickReceiver()

	command := proto.RequestCommandTCP
	if firstPacket.Destination().IsUDP() {
		command = proto.RequestCommandUDP
	}
	request := &proto.RequestHeader{
		Version: raw.Version,
		User:    vNextUser,
		Command: command,
		Address: firstPacket.Destination().Address(),
		Port:    firstPacket.Destination().Port(),
	}
	if command == proto.RequestCommandUDP {
		request.Option |= proto.RequestOptionChunkStream
	}

	return this.startCommunicate(request, vNextAddress, ray, firstPacket)
}

func (handler *VMessOutboundHandler) Dispatch(firstPacket v2net.Packet, ray ray.OutboundRay) error {
	vNextList := handler.vNextList
	if firstPacket.Destination().IsUDP() {
		vNextList = handler.vNextListUDP
	}
	vNextAddress, vNextUser := pickVNext(vNextList)

	command := protocol.CmdTCP
	if firstPacket.Destination().IsUDP() {
		command = protocol.CmdUDP
	}
	request := &protocol.VMessRequest{
		Version: protocol.Version,
		User:    vNextUser,
		Command: command,
		Address: firstPacket.Destination().Address(),
	}

	buffer := alloc.NewSmallBuffer()
	defer buffer.Release()
	v2net.ReadAllBytes(rand.Reader, buffer.Value[:36]) // 16 + 16 + 4
	request.RequestIV = buffer.Value[:16]
	request.RequestKey = buffer.Value[16:32]
	request.ResponseHeader = buffer.Value[32:36]

	return startCommunicate(request, vNextAddress, ray, firstPacket)
}

func (handler *OutboundConnectionHandler) Dispatch(packet v2net.Packet, ray core.OutboundRay) error {
	input := ray.OutboundInput()
	output := ray.OutboundOutput()

	handler.Destination = packet.Destination()
	if packet.Chunk() != nil {
		handler.Data2Send.Write(packet.Chunk().Value)
	}

	go func() {
		for {
			data, open := <-input
			if !open {
				break
			}
			handler.Data2Send.Write(data.Value)
			data.Release()
		}
		response := alloc.NewBuffer()
		response.Clear()
		response.Append(handler.Data2Return)
		output <- response
		close(output)
	}()

	return nil
}

func (handler *VMessOutboundHandler) Dispatch(firstPacket v2net.Packet, ray core.OutboundRay) error {
	vNextList := handler.vNextList
	if firstPacket.Destination().IsUDP() {
		vNextList = handler.vNextListUDP
	}
	vNextAddress, vNextUser := pickVNext(vNextList)

	command := protocol.CmdTCP
	if firstPacket.Destination().IsUDP() {
		command = protocol.CmdUDP
	}
	request := &protocol.VMessRequest{
		Version: protocol.Version,
		UserId:  vNextUser.Id,
		Command: command,
		Address: firstPacket.Destination().Address(),
	}

	buffer := make([]byte, 36) // 16 + 16 + 4
	rand.Read(buffer)
	request.RequestIV = buffer[:16]
	request.RequestKey = buffer[16:32]
	request.ResponseHeader = buffer[32:]

	go startCommunicate(request, vNextAddress, ray, firstPacket)
	return nil
}

func (handler *OutboundConnectionHandler) Dispatch(packet v2net.Packet, ray core.OutboundRay) error {
	input := ray.OutboundInput()
	output := ray.OutboundOutput()

	handler.Destination = packet.Destination()
	if packet.Chunk() != nil {
		handler.Data2Send.Write(packet.Chunk())
	}

	go func() {
		for {
			data, open := <-input
			if !open {
				break
			}
			handler.Data2Send.Write(data)
		}
		dataCopy := make([]byte, len(handler.Data2Return))
		copy(dataCopy, handler.Data2Return)
		output <- dataCopy
		close(output)
	}()

	return nil
}

func (this *VMessOutboundHandler) handleRequest(session *raw.ClientSession, conn net.Conn, request *proto.RequestHeader, firstPacket v2net.Packet, input <-chan *alloc.Buffer, finish *sync.Mutex) {
	defer finish.Unlock()

	writer := v2io.NewBufferedWriter(conn)
	session.EncodeRequestHeader(request, writer)

	// Send first packet of payload together with request, in favor of small requests.
	firstChunk := firstPacket.Chunk()
	moreChunks := firstPacket.MoreChunks()

	for firstChunk == nil && moreChunks {
		firstChunk, moreChunks = <-input
	}

	if firstChunk == nil && !moreChunks {
		log.Warning("VMessOut: Nothing to send. Existing...")
		return
	}

	if request.Option.IsChunkStream() {
		vmessio.Authenticate(firstChunk)
	}

	bodyWriter := session.EncodeRequestBody(writer)
	bodyWriter.Write(firstChunk.Value)
	firstChunk.Release()

	writer.SetCached(false)

	if moreChunks {
		var streamWriter v2io.ReleasableWriter = v2io.NewAdaptiveWriter(bodyWriter)
		if request.Option.IsChunkStream() {
			streamWriter = vmessio.NewAuthChunkWriter(streamWriter)
		}
		v2io.ChanToWriter(streamWriter, input)
		streamWriter.Release()
	}
	return
}

func (handler *OutboundConnectionHandler) Create(point *core.Point, packet v2net.Packet) (core.OutboundConnectionHandler, error) {
	handler.Destination = packet.Destination()
	if packet.Chunk() != nil {
		handler.Data2Send.Write(packet.Chunk())
	}

	return handler, nil
}

func startCommunicate(request *protocol.VMessRequest, dest v2net.Destination, ray core.OutboundRay, firstPacket v2net.Packet) error {
	conn, err := net.DialTCP(dest.Network(), nil, &net.TCPAddr{dest.Address().IP(), int(dest.Address().Port()), ""})
	if err != nil {
		log.Error("Failed to open tcp (%s): %v", dest.String(), err)
		if ray != nil {
			close(ray.OutboundOutput())
		}
		return err
	}
	log.Info("VMessOut: Tunneling request for %s", request.Address.String())

	defer conn.Close()

	if chunk := firstPacket.Chunk(); chunk != nil {
		conn.Write(chunk)
	}

	if !firstPacket.MoreChunks() {
		if ray != nil {
			close(ray.OutboundOutput())
		}
		return nil
	}

	input := ray.OutboundInput()
	output := ray.OutboundOutput()
	var requestFinish, responseFinish sync.Mutex
	requestFinish.Lock()
	responseFinish.Lock()

	go handleRequest(conn, request, input, &requestFinish)
	go handleResponse(conn, request, output, &responseFinish)

	requestFinish.Lock()
	conn.CloseWrite()
	responseFinish.Lock()
	return nil
}

func (this *Point) FilterPacketAndDispatch(packet v2net.Packet, link ray.OutboundRay, dispatcher proxy.OutboundConnectionHandler) {
	// Filter empty packets
	chunk := packet.Chunk()
	moreChunks := packet.MoreChunks()
	changed := false
	for chunk == nil && moreChunks {
		changed = true
		chunk, moreChunks = <-link.OutboundInput()
	}
	if chunk == nil && !moreChunks {
		close(link.OutboundOutput())
		return
	}

	if changed {
		packet = v2net.NewPacket(packet.Destination(), chunk, moreChunks)
	}

	dispatcher.Dispatch(packet, link)
}