Add session context outbounds as slice (#3356)

* Add session context outbounds as slice

slice is needed for dialer proxy where two outbounds work on top of each other
There are two sets of target addr for example
It also enable Xtls to correctly do splice copy by checking both outbounds are ready to do direct copy

* Fill outbound tag info

* Splice now checks capalibility from all outbounds

* Fix unit tests

common/mux/client.go

@@ -148,9 +148,10 @@ func (f *DialingWorkerFactory) Create() (*ClientWorker, error) {
 	}
 
 	go func(p proxy.Outbound, d internet.Dialer, c common.Closable) {
-		ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{
+		outbounds := []*session.Outbound{{
 			Target: net.TCPDestination(muxCoolAddress, muxCoolPort),
-		})
+		}}
+		ctx := session.ContextWithOutbounds(context.Background(), outbounds)
 		ctx, cancel := context.WithCancel(ctx)
 
 		if err := p.Process(ctx, &transport.Link{Reader: uplinkReader, Writer: downlinkWriter}, d); err != nil {
@@ -242,17 +243,18 @@ func writeFirstPayload(reader buf.Reader, writer *Writer) error {
 }
 
 func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
-	dest := session.OutboundFromContext(ctx).Target
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
 	transferType := protocol.TransferTypeStream
-	if dest.Network == net.Network_UDP {
+	if ob.Target.Network == net.Network_UDP {
 		transferType = protocol.TransferTypePacket
 	}
 	s.transferType = transferType
-	writer := NewWriter(s.ID, dest, output, transferType, xudp.GetGlobalID(ctx))
+	writer := NewWriter(s.ID, ob.Target, output, transferType, xudp.GetGlobalID(ctx))
 	defer s.Close(false)
 	defer writer.Close()
 
-	newError("dispatching request to ", dest).WriteToLog(session.ExportIDToError(ctx))
+	newError("dispatching request to ", ob.Target).WriteToLog(session.ExportIDToError(ctx))
 	if err := writeFirstPayload(s.input, writer); err != nil {
 		newError("failed to write first payload").Base(err).WriteToLog(session.ExportIDToError(ctx))
 		writer.hasError = true

common/mux/client_test.go

@@ -86,9 +86,9 @@ func TestClientWorkerClose(t *testing.T) {
 	}
 
 	tr1, tw1 := pipe.New(pipe.WithoutSizeLimit())
-	ctx1 := session.ContextWithOutbound(context.Background(), &session.Outbound{
+	ctx1 := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
 		Target: net.TCPDestination(net.DomainAddress("www.example.com"), 80),
-	})
+	}})
 	common.Must(manager.Dispatch(ctx1, &transport.Link{
 		Reader: tr1,
 		Writer: tw1,
@@ -103,9 +103,9 @@ func TestClientWorkerClose(t *testing.T) {
 	}
 
 	tr2, tw2 := pipe.New(pipe.WithoutSizeLimit())
-	ctx2 := session.ContextWithOutbound(context.Background(), &session.Outbound{
+	ctx2 := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
 		Target: net.TCPDestination(net.DomainAddress("www.example.com"), 80),
-	})
+	}})
 	common.Must(manager.Dispatch(ctx2, &transport.Link{
 		Reader: tr2,
 		Writer: tw2,

common/session/context.go

@@ -51,13 +51,13 @@ func InboundFromContext(ctx context.Context) *Inbound {
 	return nil
 }
 
-func ContextWithOutbound(ctx context.Context, outbound *Outbound) context.Context {
-	return context.WithValue(ctx, outboundSessionKey, outbound)
+func ContextWithOutbounds(ctx context.Context, outbounds []*Outbound) context.Context {
+	return context.WithValue(ctx, outboundSessionKey, outbounds)
 }
 
-func OutboundFromContext(ctx context.Context) *Outbound {
-	if outbound, ok := ctx.Value(outboundSessionKey).(*Outbound); ok {
-		return outbound
+func OutboundsFromContext(ctx context.Context) []*Outbound {
+	if outbounds, ok := ctx.Value(outboundSessionKey).([]*Outbound); ok {
+		return outbounds
 	}
 	return nil
 }

common/session/session.go

@@ -50,18 +50,11 @@ type Inbound struct {
 	Conn net.Conn
 	// Timer of the inbound buf copier. May be nil.
 	Timer *signal.ActivityTimer
-	// CanSpliceCopy is a property for this connection, set by both inbound and outbound
+	// CanSpliceCopy is a property for this connection
 	// 1 = can, 2 = after processing protocol info should be able to, 3 = cannot
 	CanSpliceCopy int
 }
 
-func(i *Inbound) SetCanSpliceCopy(canSpliceCopy int) int {
-	if canSpliceCopy > i.CanSpliceCopy {
-		i.CanSpliceCopy = canSpliceCopy
-	}
-	return i.CanSpliceCopy
-}
-
 // Outbound is the metadata of an outbound connection.
 type Outbound struct {
 	// Target address of the outbound connection.
@@ -70,10 +63,15 @@ type Outbound struct {
 	RouteTarget    net.Destination
 	// Gateway address
 	Gateway net.Address
+	// Tag of the outbound proxy that handles the connection.
+	Tag string
 	// Name of the outbound proxy that handles the connection.
 	Name string
 	// Conn is actually internet.Connection. May be nil. It is currently nil for outbound with proxySettings 
 	Conn net.Conn
+	// CanSpliceCopy is a property for this connection
+	// 1 = can, 2 = after processing protocol info should be able to, 3 = cannot
+	CanSpliceCopy int
 }
 
 // SniffingRequest controls the behavior of content sniffing.

common/singbridge/dialer.go

@@ -43,9 +43,14 @@ func NewOutboundDialer(outbound proxy.Outbound, dialer internet.Dialer) *XrayOut
 }
 
 func (d *XrayOutboundDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
-	ctx = session.ContextWithOutbound(ctx, &session.Outbound{
-		Target: ToDestination(destination, ToNetwork(network)),
-	})
+	outbounds := session.OutboundsFromContext(ctx)
+	if len(outbounds) == 0 {
+		outbounds = []*session.Outbound{{}}
+		ctx = session.ContextWithOutbounds(ctx, outbounds)
+	}
+	ob := outbounds[len(outbounds) - 1]
+	ob.Target = ToDestination(destination, ToNetwork(network))
+	
 	opts := []pipe.Option{pipe.WithSizeLimit(64 * 1024)}
 	uplinkReader, uplinkWriter := pipe.New(opts...)
 	downlinkReader, downlinkWriter := pipe.New(opts...)