XTLS Vision: Apply padding to single XUDP by default at client side

Requires Xray-core v1.8.1+ at server side: https://github.com/XTLS/Xray-core/commit/242f3b0e0b635699db26a991aa6c0cd47927e8b6

proxy/vless/encoding/addons.go

@@ -62,11 +62,7 @@ func DecodeHeaderAddons(buffer *buf.Buffer, reader io.Reader) (*Addons, error) {
 // EncodeBodyAddons returns a Writer that auto-encrypt content written by caller.
 func EncodeBodyAddons(writer io.Writer, request *protocol.RequestHeader, requestAddons *Addons, state *proxy.TrafficState, context context.Context) buf.Writer {
 	if request.Command == protocol.RequestCommandUDP {
-		w := writer.(buf.Writer)
-		if requestAddons.Flow == vless.XRV {
-			w = proxy.NewVisionWriter(w, state, context)
-		}
-		return NewMultiLengthPacketWriter(w)
+		return NewMultiLengthPacketWriter(writer.(buf.Writer))
 	}
 	w := buf.NewWriter(writer)
 	if requestAddons.Flow == vless.XRV {

proxy/vless/encoding/encoding.go

@@ -176,7 +176,6 @@ func DecodeResponseHeader(reader io.Reader, request *protocol.RequestHeader) (*A
 // XtlsRead filter and read xtls protocol
 func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, conn net.Conn, input *bytes.Reader, rawInput *bytes.Buffer, trafficState *proxy.TrafficState, ctx context.Context) error {
 	err := func() error {
-		visionReader := proxy.NewVisionReader(reader, trafficState, ctx)
 		for {
 			if trafficState.ReaderSwitchToDirectCopy {
 				var writerConn net.Conn
@@ -188,7 +187,7 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
 				}
 				return proxy.CopyRawConnIfExist(ctx, conn, writerConn, writer, timer)
 			}
-			buffer, err := visionReader.ReadMultiBuffer()
+			buffer, err := reader.ReadMultiBuffer()
 			if !buffer.IsEmpty() {
 				timer.Update()
 				if trafficState.ReaderSwitchToDirectCopy {

proxy/vless/inbound/inbound.go

@@ -522,6 +522,7 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
 
 		if requestAddons.Flow == vless.XRV {
 			ctx1 := session.ContextWithInbound(ctx, nil) // TODO enable splice
+			clientReader = proxy.NewVisionReader(clientReader, trafficState, ctx1)
 			err = encoding.XtlsRead(clientReader, serverWriter, timer, connection, input, rawInput, trafficState, ctx1)
 		} else {
 			// from clientReader.ReadMultiBuffer to serverWriter.WriteMultiBufer

proxy/vless/outbound/outbound.go

@@ -138,7 +138,6 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 			if !allowUDP443 && request.Port == 443 {
 				return newError("XTLS rejected UDP/443 traffic").AtInfo()
 			}
-			requestAddons.Flow = ""
 		case protocol.RequestCommandMux:
 			fallthrough // let server break Mux connections that contain TCP requests
 		case protocol.RequestCommandTCP:
@@ -185,7 +184,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 	clientReader := link.Reader // .(*pipe.Reader)
 	clientWriter := link.Writer // .(*pipe.Writer)
 	trafficState := proxy.NewTrafficState(account.ID.Bytes())
-	if request.Command == protocol.RequestCommandUDP && h.cone && request.Port != 53 && request.Port != 443 {
+	if request.Command == protocol.RequestCommandUDP && (requestAddons.Flow == vless.XRV || (h.cone && request.Port != 53 && request.Port != 443)) {
 		request.Command = protocol.RequestCommandMux
 		request.Address = net.DomainAddress("v1.mux.cool")
 		request.Port = net.Port(666)
@@ -266,8 +265,15 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 
 		// default: serverReader := buf.NewReader(conn)
 		serverReader := encoding.DecodeBodyAddons(conn, request, responseAddons)
+		if requestAddons.Flow == vless.XRV {
+			serverReader = proxy.NewVisionReader(serverReader, trafficState, ctx)
+		}
 		if request.Command == protocol.RequestCommandMux && request.Port == 666 {
-			serverReader = xudp.NewPacketReader(conn)
+			if requestAddons.Flow == vless.XRV {
+				serverReader = xudp.NewPacketReader(&buf.BufferedReader{Reader: serverReader})
+			} else {
+				serverReader = xudp.NewPacketReader(conn)
+			}
 		}
 
 		if requestAddons.Flow == vless.XRV {