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

app/dispatcher/default.go

@@ -218,11 +218,12 @@ func (d *DefaultDispatcher) Dispatch(ctx context.Context, destination net.Destin
 	if !destination.IsValid() {
 		panic("Dispatcher: Invalid destination.")
 	}
-	ob := session.OutboundFromContext(ctx)
-	if ob == nil {
-		ob = &session.Outbound{}
-		ctx = session.ContextWithOutbound(ctx, ob)
+	outbounds := session.OutboundsFromContext(ctx)
+	if len(outbounds) == 0 {
+		outbounds = []*session.Outbound{{}}
+		ctx = session.ContextWithOutbounds(ctx, outbounds)
 	}
+	ob := outbounds[len(outbounds) - 1]
 	ob.OriginalTarget = destination
 	ob.Target = destination
 	content := session.ContentFromContext(ctx)
@@ -274,11 +275,12 @@ func (d *DefaultDispatcher) DispatchLink(ctx context.Context, destination net.De
 	if !destination.IsValid() {
 		return newError("Dispatcher: Invalid destination.")
 	}
-	ob := session.OutboundFromContext(ctx)
-	if ob == nil {
-		ob = &session.Outbound{}
-		ctx = session.ContextWithOutbound(ctx, ob)
+	outbounds := session.OutboundsFromContext(ctx)
+	if len(outbounds) == 0 {
+		outbounds = []*session.Outbound{{}}
+		ctx = session.ContextWithOutbounds(ctx, outbounds)
 	}
+	ob := outbounds[len(outbounds) - 1]
 	ob.OriginalTarget = destination
 	ob.Target = destination
 	content := session.ContentFromContext(ctx)
@@ -368,7 +370,8 @@ func sniffer(ctx context.Context, cReader *cachedReader, metadataOnly bool, netw
 	return contentResult, contentErr
 }
 func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.Link, destination net.Destination) {
-	ob := session.OutboundFromContext(ctx)
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
 	if hosts, ok := d.dns.(dns.HostsLookup); ok && destination.Address.Family().IsDomain() {
 		proxied := hosts.LookupHosts(ob.Target.String())
 		if proxied != nil {
@@ -425,6 +428,7 @@ func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.
 		return
 	}
 
+	ob.Tag = handler.Tag()
 	if accessMessage := log.AccessMessageFromContext(ctx); accessMessage != nil {
 		if tag := handler.Tag(); tag != "" {
 			if inTag == "" {

app/dispatcher/fakednssniffer.go

@@ -26,11 +26,12 @@ func newFakeDNSSniffer(ctx context.Context) (protocolSnifferWithMetadata, error)
 		return protocolSnifferWithMetadata{}, errNotInit
 	}
 	return protocolSnifferWithMetadata{protocolSniffer: func(ctx context.Context, bytes []byte) (SniffResult, error) {
-		Target := session.OutboundFromContext(ctx).Target
-		if Target.Network == net.Network_TCP || Target.Network == net.Network_UDP {
-			domainFromFakeDNS := fakeDNSEngine.GetDomainFromFakeDNS(Target.Address)
+		outbounds := session.OutboundsFromContext(ctx)
+		ob := outbounds[len(outbounds) - 1]
+		if ob.Target.Network == net.Network_TCP || ob.Target.Network == net.Network_UDP {
+			domainFromFakeDNS := fakeDNSEngine.GetDomainFromFakeDNS(ob.Target.Address)
 			if domainFromFakeDNS != "" {
-				newError("fake dns got domain: ", domainFromFakeDNS, " for ip: ", Target.Address.String()).WriteToLog(session.ExportIDToError(ctx))
+				newError("fake dns got domain: ", domainFromFakeDNS, " for ip: ", ob.Target.Address.String()).WriteToLog(session.ExportIDToError(ctx))
 				return &fakeDNSSniffResult{domainName: domainFromFakeDNS}, nil
 			}
 		}
@@ -38,7 +39,7 @@ func newFakeDNSSniffer(ctx context.Context) (protocolSnifferWithMetadata, error)
 		if ipAddressInRangeValueI := ctx.Value(ipAddressInRange); ipAddressInRangeValueI != nil {
 			ipAddressInRangeValue := ipAddressInRangeValueI.(*ipAddressInRangeOpt)
 			if fkr0, ok := fakeDNSEngine.(dns.FakeDNSEngineRev0); ok {
-				inPool := fkr0.IsIPInIPPool(Target.Address)
+				inPool := fkr0.IsIPInIPPool(ob.Target.Address)
 				ipAddressInRangeValue.addressInRange = &inPool
 			}
 		}

app/proxyman/inbound/worker.go

@@ -60,7 +60,7 @@ func (w *tcpWorker) callback(conn stat.Connection) {
 	sid := session.NewID()
 	ctx = session.ContextWithID(ctx, sid)
 
-	var outbound = &session.Outbound{}
+	outbounds := []*session.Outbound{{}}
 	if w.recvOrigDest {
 		var dest net.Destination
 		switch getTProxyType(w.stream) {
@@ -75,10 +75,10 @@ func (w *tcpWorker) callback(conn stat.Connection) {
 			dest = net.DestinationFromAddr(conn.LocalAddr())
 		}
 		if dest.IsValid() {
-			outbound.Target = dest
+			outbounds[0].Target = dest
 		}
 	}
-	ctx = session.ContextWithOutbound(ctx, outbound)
+	ctx = session.ContextWithOutbounds(ctx, outbounds)
 
 	if w.uplinkCounter != nil || w.downlinkCounter != nil {
 		conn = &stat.CounterConnection{
@@ -309,9 +309,10 @@ func (w *udpWorker) callback(b *buf.Buffer, source net.Destination, originalDest
 			ctx = session.ContextWithID(ctx, sid)
 
 			if originalDest.IsValid() {
-				ctx = session.ContextWithOutbound(ctx, &session.Outbound{
+				outbounds := []*session.Outbound{{
 					Target: originalDest,
-				})
+				}}
+				ctx = session.ContextWithOutbounds(ctx, outbounds)
 			}
 			ctx = session.ContextWithInbound(ctx, &session.Inbound{
 				Source:  source,

app/proxyman/outbound/handler.go

@@ -169,10 +169,11 @@ func (h *Handler) Tag() string {
 
 // Dispatch implements proxy.Outbound.Dispatch.
 func (h *Handler) Dispatch(ctx context.Context, link *transport.Link) {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound.Target.Network == net.Network_UDP && outbound.OriginalTarget.Address != nil && outbound.OriginalTarget.Address != outbound.Target.Address {
-		link.Reader = &buf.EndpointOverrideReader{Reader: link.Reader, Dest: outbound.Target.Address, OriginalDest: outbound.OriginalTarget.Address}
-		link.Writer = &buf.EndpointOverrideWriter{Writer: link.Writer, Dest: outbound.Target.Address, OriginalDest: outbound.OriginalTarget.Address}
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if ob.Target.Network == net.Network_UDP && ob.OriginalTarget.Address != nil && ob.OriginalTarget.Address != ob.Target.Address {
+		link.Reader = &buf.EndpointOverrideReader{Reader: link.Reader, Dest: ob.Target.Address, OriginalDest: ob.OriginalTarget.Address}
+		link.Writer = &buf.EndpointOverrideWriter{Writer: link.Writer, Dest: ob.Target.Address, OriginalDest: ob.OriginalTarget.Address}
 	}
 	if h.mux != nil {
 		test := func(err error) {
@@ -183,7 +184,7 @@ func (h *Handler) Dispatch(ctx context.Context, link *transport.Link) {
 				common.Interrupt(link.Writer)
 			}
 		}
-		if outbound.Target.Network == net.Network_UDP && outbound.Target.Port == 443 {
+		if ob.Target.Network == net.Network_UDP && ob.Target.Port == 443 {
 			switch h.udp443 {
 			case "reject":
 				test(newError("XUDP rejected UDP/443 traffic").AtInfo())
@@ -192,7 +193,7 @@ func (h *Handler) Dispatch(ctx context.Context, link *transport.Link) {
 				goto out
 			}
 		}
-		if h.xudp != nil && outbound.Target.Network == net.Network_UDP {
+		if h.xudp != nil && ob.Target.Network == net.Network_UDP {
 			if !h.xudp.Enabled {
 				goto out
 			}
@@ -243,10 +244,11 @@ func (h *Handler) Dial(ctx context.Context, dest net.Destination) (stat.Connecti
 			handler := h.outboundManager.GetHandler(tag)
 			if handler != nil {
 				newError("proxying to ", tag, " for dest ", dest).AtDebug().WriteToLog(session.ExportIDToError(ctx))
-				ctx = session.ContextWithOutbound(ctx, &session.Outbound{
+				outbounds := session.OutboundsFromContext(ctx)
+				ctx = session.ContextWithOutbounds(ctx, append(outbounds, &session.Outbound{
 					Target: dest,
-				})
-
+					Tag: tag,
+				})) // add another outbound in session ctx
 				opts := pipe.OptionsFromContext(ctx)
 				uplinkReader, uplinkWriter := pipe.New(opts...)
 				downlinkReader, downlinkWriter := pipe.New(opts...)
@@ -266,15 +268,12 @@ func (h *Handler) Dial(ctx context.Context, dest net.Destination) (stat.Connecti
 		}
 
 		if h.senderSettings.Via != nil {
-			outbound := session.OutboundFromContext(ctx)
-			if outbound == nil {
-				outbound = new(session.Outbound)
-				ctx = session.ContextWithOutbound(ctx, outbound)
-			}
+			outbounds := session.OutboundsFromContext(ctx)
+			ob := outbounds[len(outbounds) - 1]
 			if h.senderSettings.ViaCidr == "" {
-				outbound.Gateway = h.senderSettings.Via.AsAddress()
+				ob.Gateway = h.senderSettings.Via.AsAddress()
 			} else { //Get a random address.
-				outbound.Gateway = ParseRandomIPv6(h.senderSettings.Via.AsAddress(), h.senderSettings.ViaCidr)
+				ob.Gateway = ParseRandomIPv6(h.senderSettings.Via.AsAddress(), h.senderSettings.ViaCidr)
 			}
 		}
 	}
@@ -285,10 +284,9 @@ func (h *Handler) Dial(ctx context.Context, dest net.Destination) (stat.Connecti
 
 	conn, err := internet.Dial(ctx, dest, h.streamSettings)
 	conn = h.getStatCouterConnection(conn)
-	outbound := session.OutboundFromContext(ctx)
-	if outbound != nil {
-		outbound.Conn = conn
-	}
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	ob.Conn = conn
 	return conn, err
 }
 

app/proxyman/outbound/handler_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/xtls/xray-core/app/stats"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/serial"
+	"github.com/xtls/xray-core/common/session"
 	core "github.com/xtls/xray-core/core"
 	"github.com/xtls/xray-core/features/outbound"
 	"github.com/xtls/xray-core/proxy/freedom"
@@ -44,6 +45,7 @@ func TestOutboundWithoutStatCounter(t *testing.T) {
 	v, _ := core.New(config)
 	v.AddFeature((outbound.Manager)(new(Manager)))
 	ctx := context.WithValue(context.Background(), xrayKey, v)
+	ctx = session.ContextWithOutbounds(ctx, []*session.Outbound{{}})
 	h, _ := NewHandler(ctx, &core.OutboundHandlerConfig{
 		Tag:           "tag",
 		ProxySettings: serial.ToTypedMessage(&freedom.Config{}),
@@ -73,6 +75,7 @@ func TestOutboundWithStatCounter(t *testing.T) {
 	v, _ := core.New(config)
 	v.AddFeature((outbound.Manager)(new(Manager)))
 	ctx := context.WithValue(context.Background(), xrayKey, v)
+	ctx = session.ContextWithOutbounds(ctx, []*session.Outbound{{}})
 	h, _ := NewHandler(ctx, &core.OutboundHandlerConfig{
 		Tag:           "tag",
 		ProxySettings: serial.ToTypedMessage(&freedom.Config{}),

app/reverse/portal.go

@@ -62,12 +62,13 @@ func (p *Portal) Close() error {
 }
 
 func (p *Portal) HandleConnection(ctx context.Context, link *transport.Link) error {
-	outboundMeta := session.OutboundFromContext(ctx)
-	if outboundMeta == nil {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if ob == nil {
 		return newError("outbound metadata not found").AtError()
 	}
 
-	if isDomain(outboundMeta.Target, p.domain) {
+	if isDomain(ob.Target, p.domain) {
 		muxClient, err := mux.NewClientWorker(*link, mux.ClientStrategy{})
 		if err != nil {
 			return newError("failed to create mux client worker").Base(err).AtWarning()
@@ -206,9 +207,10 @@ func NewPortalWorker(client *mux.ClientWorker) (*PortalWorker, error) {
 	downlinkReader, downlinkWriter := pipe.New(opt...)
 
 	ctx := context.Background()
-	ctx = session.ContextWithOutbound(ctx, &session.Outbound{
+	outbounds := []*session.Outbound{{
 		Target: net.UDPDestination(net.DomainAddress(internalDomain), 0),
-	})
+	}}
+	ctx = session.ContextWithOutbounds(ctx, outbounds)
 	f := client.Dispatch(ctx, &transport.Link{
 		Reader: uplinkReader,
 		Writer: downlinkWriter,

app/router/router_test.go

@@ -45,7 +45,9 @@ func TestSimpleRouter(t *testing.T) {
 		HandlerSelector: mockHs,
 	}, nil))
 
-	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("example.com"), 80)})
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
+		Target: net.TCPDestination(net.DomainAddress("example.com"), 80),
+	}})
 	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
 	if tag := route.GetOutboundTag(); tag != "test" {
@@ -86,7 +88,9 @@ func TestSimpleBalancer(t *testing.T) {
 		HandlerSelector: mockHs,
 	}, nil))
 
-	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("example.com"), 80)})
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
+		Target: net.TCPDestination(net.DomainAddress("example.com"), 80),
+	}})
 	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
 	if tag := route.GetOutboundTag(); tag != "test" {
@@ -174,7 +178,9 @@ func TestIPOnDemand(t *testing.T) {
 	r := new(Router)
 	common.Must(r.Init(context.TODO(), config, mockDNS, nil, nil))
 
-	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("example.com"), 80)})
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
+		Target: net.TCPDestination(net.DomainAddress("example.com"), 80),
+	}})
 	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
 	if tag := route.GetOutboundTag(); tag != "test" {
@@ -213,7 +219,9 @@ func TestIPIfNonMatchDomain(t *testing.T) {
 	r := new(Router)
 	common.Must(r.Init(context.TODO(), config, mockDNS, nil, nil))
 
-	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("example.com"), 80)})
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
+		Target: net.TCPDestination(net.DomainAddress("example.com"), 80),
+	}})
 	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
 	if tag := route.GetOutboundTag(); tag != "test" {
@@ -247,7 +255,9 @@ func TestIPIfNonMatchIP(t *testing.T) {
 	r := new(Router)
 	common.Must(r.Init(context.TODO(), config, mockDNS, nil, nil))
 
-	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.LocalHostIP, 80)})
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{
+		Target: net.TCPDestination(net.LocalHostIP, 80),
+	}})
 	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
 	if tag := route.GetOutboundTag(); tag != "test" {

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...)

features/routing/session/context.go

@@ -124,9 +124,11 @@ func (ctx *Context) GetSkipDNSResolve() bool {
 
 // AsRoutingContext creates a context from context.context with session info.
 func AsRoutingContext(ctx context.Context) routing.Context {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
 	return &Context{
 		Inbound:  session.InboundFromContext(ctx),
-		Outbound: session.OutboundFromContext(ctx),
+		Outbound: ob,
 		Content:  session.ContentFromContext(ctx),
 	}
 }

proxy/blackhole/blackhole.go

@@ -31,10 +31,9 @@ func New(ctx context.Context, config *Config) (*Handler, error) {
 
 // Process implements OutboundHandler.Dispatch().
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound != nil {
-		outbound.Name = "blackhole"
-	}
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	ob.Name = "blackhole"
 	
 	nBytes := h.response.WriteTo(link.Writer)
 	if nBytes > 0 {

proxy/blackhole/blackhole_test.go

@@ -7,13 +7,15 @@ import (
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/serial"
+	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/proxy/blackhole"
 	"github.com/xtls/xray-core/transport"
 	"github.com/xtls/xray-core/transport/pipe"
 )
 
 func TestBlackholeHTTPResponse(t *testing.T) {
-	handler, err := blackhole.New(context.Background(), &blackhole.Config{
+	ctx := session.ContextWithOutbounds(context.Background(), []*session.Outbound{{}})
+	handler, err := blackhole.New(ctx, &blackhole.Config{
 		Response: serial.ToTypedMessage(&blackhole.HTTPResponse{}),
 	})
 	common.Must(err)
@@ -32,7 +34,7 @@ func TestBlackholeHTTPResponse(t *testing.T) {
 		Reader: reader,
 		Writer: writer,
 	}
-	common.Must(handler.Process(context.Background(), &link, nil))
+	common.Must(handler.Process(ctx, &link, nil))
 	common.Must(rerr)
 	if mb.IsEmpty() {
 		t.Error("expect http response, but nothing")

proxy/dns/dns.go

@@ -96,15 +96,16 @@ func parseIPQuery(b []byte) (r bool, domain string, id uint16, qType dnsmessage.
 
 // Process implements proxy.Outbound.
 func (h *Handler) Process(ctx context.Context, link *transport.Link, d internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("invalid outbound")
 	}
-	outbound.Name = "dns"
+	ob.Name = "dns"
 
-	srcNetwork := outbound.Target.Network
+	srcNetwork := ob.Target.Network
 
-	dest := outbound.Target
+	dest := ob.Target
 	if h.server.Network != net.Network_Unknown {
 		dest.Network = h.server.Network
 	}

proxy/dokodemo/dokodemo.go

@@ -86,10 +86,15 @@ func (d *DokodemoDoor) Process(ctx context.Context, network net.Network, conn st
 
 	destinationOverridden := false
 	if d.config.FollowRedirect {
-		if outbound := session.OutboundFromContext(ctx); outbound != nil && outbound.Target.IsValid() {
-			dest = outbound.Target
-			destinationOverridden = true
-		} else if handshake, ok := conn.(hasHandshakeAddressContext); ok {
+		outbounds := session.OutboundsFromContext(ctx)
+		if len(outbounds) > 0 {
+			ob := outbounds[len(outbounds) - 1]
+			if ob.Target.IsValid() {
+				dest = ob.Target
+				destinationOverridden = true
+			}
+		}
+		if handshake, ok := conn.(hasHandshakeAddressContext); ok && !destinationOverridden {
 			addr := handshake.HandshakeAddressContext(ctx)
 			if addr != nil {
 				dest.Address = addr
@@ -103,7 +108,7 @@ func (d *DokodemoDoor) Process(ctx context.Context, network net.Network, conn st
 
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "dokodemo-door"
-	inbound.SetCanSpliceCopy(1)
+	inbound.CanSpliceCopy = 1
 	inbound.User = &protocol.MemoryUser{
 		Level: d.config.UserLevel,
 	}

proxy/freedom/freedom.go

@@ -106,16 +106,16 @@ func isValidAddress(addr *net.IPOrDomain) bool {
 
 // Process implements proxy.Outbound.
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified.")
 	}
-	outbound.Name = "freedom"
+	ob.Name = "freedom"
+	ob.CanSpliceCopy = 1
 	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(1)
-	}
-	destination := outbound.Target
+
+	destination := ob.Target
 	UDPOverride := net.UDPDestination(nil, 0)
 	if h.config.DestinationOverride != nil {
 		server := h.config.DestinationOverride.Server

proxy/http/client.go

@@ -69,16 +69,14 @@ func NewClient(ctx context.Context, config *ClientConfig) (*Client, error) {
 
 // Process implements proxy.Outbound.Process. We first create a socket tunnel via HTTP CONNECT method, then redirect all inbound traffic to that tunnel.
 func (c *Client) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified.")
 	}
-	outbound.Name = "http"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(2)
-	}
-	target := outbound.Target
+	ob.Name = "http"
+	ob.CanSpliceCopy = 2
+	target := ob.Target
 	targetAddr := target.NetAddr()
 
 	if target.Network == net.Network_UDP {
@@ -175,9 +173,10 @@ func fillRequestHeader(ctx context.Context, header []*Header) ([]*Header, error)
 	}
 
 	inbound := session.InboundFromContext(ctx)
-	outbound := session.OutboundFromContext(ctx)
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
 
-	if inbound == nil || outbound == nil {
+	if inbound == nil || ob == nil {
 		return nil, newError("missing inbound or outbound metadata from context")
 	}
 
@@ -186,7 +185,7 @@ func fillRequestHeader(ctx context.Context, header []*Header) ([]*Header, error)
 		Target net.Destination
 	}{
 		Source: inbound.Source,
-		Target: outbound.Target,
+		Target: ob.Target,
 	}
 
 	filled := make([]*Header, len(header))

proxy/http/server.go

@@ -85,7 +85,7 @@ type readerOnly struct {
 func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "http"
-	inbound.SetCanSpliceCopy(2)
+	inbound.CanSpliceCopy = 2
 	inbound.User = &protocol.MemoryUser{
 		Level: s.config.UserLevel,
 	}

proxy/loopback/loopback.go

@@ -22,12 +22,13 @@ type Loopback struct {
 }
 
 func (l *Loopback) Process(ctx context.Context, link *transport.Link, _ internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified.")
 	}
-	outbound.Name = "loopback"
-	destination := outbound.Target
+	ob.Name = "loopback"
+	destination := ob.Target
 
 	newError("opening connection to ", destination).WriteToLog(session.ExportIDToError(ctx))
 

proxy/proxy.go

@@ -474,45 +474,73 @@ func CopyRawConnIfExist(ctx context.Context, readerConn net.Conn, writerConn net
 	readerConn, readCounter, _ := UnwrapRawConn(readerConn)
 	writerConn, _, writeCounter := UnwrapRawConn(writerConn)
 	reader := buf.NewReader(readerConn)
-	if inbound := session.InboundFromContext(ctx); inbound != nil {
-		if tc, ok := writerConn.(*net.TCPConn); ok && readerConn != nil && writerConn != nil && (runtime.GOOS == "linux" || runtime.GOOS == "android") {
-			for inbound.CanSpliceCopy != 3 {
-				if inbound.CanSpliceCopy == 1 {
-					newError("CopyRawConn splice").WriteToLog(session.ExportIDToError(ctx))
-					statWriter, _ := writer.(*dispatcher.SizeStatWriter)
-					//runtime.Gosched() // necessary
-					time.Sleep(time.Millisecond) // without this, there will be a rare ssl error for freedom splice
-					w, err := tc.ReadFrom(readerConn)
-					if readCounter != nil {
-						readCounter.Add(w) // outbound stats
-					}
-					if writeCounter != nil {
-						writeCounter.Add(w) // inbound stats
-					}
-					if statWriter != nil {
-						statWriter.Counter.Add(w) // user stats
-					}
-					if err != nil && errors.Cause(err) != io.EOF {
-						return err
-					}
-					return nil
-				}
-				buffer, err := reader.ReadMultiBuffer()
-				if !buffer.IsEmpty() {
-					if readCounter != nil {
-						readCounter.Add(int64(buffer.Len()))
-					}
-					timer.Update()
-					if werr := writer.WriteMultiBuffer(buffer); werr != nil {
-						return werr
-					}
-				}
-				if err != nil {
-					return err
-				}
+	if runtime.GOOS != "linux" && runtime.GOOS != "android" {
+		return readV(ctx, reader, writer, timer, readCounter)
+	}
+	tc, ok := writerConn.(*net.TCPConn)
+	if !ok || readerConn == nil || writerConn == nil {
+		return readV(ctx, reader, writer, timer, readCounter)
+	}
+	inbound := session.InboundFromContext(ctx)
+	if inbound == nil || inbound.CanSpliceCopy == 3 {
+		return readV(ctx, reader, writer, timer, readCounter)
+	}
+	outbounds := session.OutboundsFromContext(ctx)
+	if len(outbounds) == 0 {
+		return readV(ctx, reader, writer, timer, readCounter)
+	}
+	for _, ob := range outbounds {
+		if ob.CanSpliceCopy == 3 {
+			return readV(ctx, reader, writer, timer, readCounter)
+		}
+	}
+
+	for {
+		inbound := session.InboundFromContext(ctx)
+		outbounds := session.OutboundsFromContext(ctx)
+		var splice = inbound.CanSpliceCopy == 1
+		for _, ob := range outbounds {
+			if ob.CanSpliceCopy != 1 {
+				splice = false
+			}
+		}
+		if splice {
+			newError("CopyRawConn splice").WriteToLog(session.ExportIDToError(ctx))
+			statWriter, _ := writer.(*dispatcher.SizeStatWriter)
+			//runtime.Gosched() // necessary
+			time.Sleep(time.Millisecond) // without this, there will be a rare ssl error for freedom splice
+			w, err := tc.ReadFrom(readerConn)
+			if readCounter != nil {
+				readCounter.Add(w) // outbound stats
+			}
+			if writeCounter != nil {
+				writeCounter.Add(w) // inbound stats
+			}
+			if statWriter != nil {
+				statWriter.Counter.Add(w) // user stats
+			}
+			if err != nil && errors.Cause(err) != io.EOF {
+				return err
 			}
+			return nil
+		}
+		buffer, err := reader.ReadMultiBuffer()
+		if !buffer.IsEmpty() {
+			if readCounter != nil {
+				readCounter.Add(int64(buffer.Len()))
+			}
+			timer.Update()
+			if werr := writer.WriteMultiBuffer(buffer); werr != nil {
+				return werr
+			}
+		}
+		if err != nil {
+			return err
 		}
 	}
+}
+
+func readV(ctx context.Context, reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, readCounter stats.Counter) error {
 	newError("CopyRawConn readv").WriteToLog(session.ExportIDToError(ctx))
 	if err := buf.Copy(reader, writer, buf.UpdateActivity(timer), buf.AddToStatCounter(readCounter)); err != nil {
 		return newError("failed to process response").Base(err)

proxy/shadowsocks/client.go

@@ -49,16 +49,14 @@ func NewClient(ctx context.Context, config *ClientConfig) (*Client, error) {
 
 // Process implements OutboundHandler.Process().
 func (c *Client) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified")
 	}
-	outbound.Name = "shadowsocks"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(3)
-	}
-	destination := outbound.Target
+	ob.Name = "shadowsocks"
+	ob.CanSpliceCopy = 3
+	destination := ob.Target
 	network := destination.Network
 
 	var server *protocol.ServerSpec

proxy/shadowsocks/server.go

@@ -73,7 +73,7 @@ func (s *Server) Network() []net.Network {
 func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "shadowsocks"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 	
 	switch network {
 	case net.Network_TCP:

proxy/shadowsocks_2022/inbound.go

@@ -66,7 +66,7 @@ func (i *Inbound) Network() []net.Network {
 func (i *Inbound) Process(ctx context.Context, network net.Network, connection stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "shadowsocks-2022"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 
 	var metadata M.Metadata
 	if inbound.Source.IsValid() {

proxy/shadowsocks_2022/inbound_multi.go

@@ -155,7 +155,7 @@ func (i *MultiUserInbound) Network() []net.Network {
 func (i *MultiUserInbound) Process(ctx context.Context, network net.Network, connection stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "shadowsocks-2022-multi"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 
 	var metadata M.Metadata
 	if inbound.Source.IsValid() {

proxy/shadowsocks_2022/inbound_relay.go

@@ -87,7 +87,7 @@ func (i *RelayInbound) Network() []net.Network {
 func (i *RelayInbound) Process(ctx context.Context, network net.Network, connection stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "shadowsocks-2022-relay"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 
 	var metadata M.Metadata
 	if inbound.Source.IsValid() {

proxy/shadowsocks_2022/outbound.go

@@ -65,15 +65,16 @@ func (o *Outbound) Process(ctx context.Context, link *transport.Link, dialer int
 	inbound := session.InboundFromContext(ctx)
 	if inbound != nil {
 		inboundConn = inbound.Conn
-		inbound.SetCanSpliceCopy(3)
 	}
 
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified")
 	}
-	outbound.Name = "shadowsocks-2022"
-	destination := outbound.Target
+	ob.Name = "shadowsocks-2022"
+	ob.CanSpliceCopy = 3
+	destination := ob.Target
 	network := destination.Network
 
 	newError("tunneling request to ", destination, " via ", o.server.NetAddr()).WriteToLog(session.ExportIDToError(ctx))

proxy/socks/client.go

@@ -57,17 +57,15 @@ func NewClient(ctx context.Context, config *ClientConfig) (*Client, error) {
 
 // Process implements proxy.Outbound.Process.
 func (c *Client) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified.")
 	}
-	outbound.Name = "socks"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(2)
-	}
+	ob.Name = "socks"
+	ob.CanSpliceCopy = 2
 	// Destination of the inner request.
-	destination := outbound.Target
+	destination := ob.Target
 
 	// Outbound server.
 	var server *protocol.ServerSpec

proxy/socks/server.go

@@ -65,7 +65,7 @@ func (s *Server) Network() []net.Network {
 func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "socks"
-	inbound.SetCanSpliceCopy(2)
+	inbound.CanSpliceCopy = 2
 	inbound.User = &protocol.MemoryUser{
 		Level: s.config.UserLevel,
 	}

proxy/trojan/client.go

@@ -50,16 +50,14 @@ func NewClient(ctx context.Context, config *ClientConfig) (*Client, error) {
 
 // Process implements OutboundHandler.Process().
 func (c *Client) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified")
 	}
-	outbound.Name = "trojan"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(3)
-	}
-	destination := outbound.Target
+	ob.Name = "trojan"
+	ob.CanSpliceCopy = 3
+	destination := ob.Target
 	network := destination.Network
 
 	var server *protocol.ServerSpec

proxy/trojan/server.go

@@ -215,7 +215,7 @@ func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Con
 
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "trojan"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 	inbound.User = user
 	sessionPolicy = s.policyManager.ForLevel(user.Level)
 

proxy/vless/encoding/encoding.go

@@ -174,15 +174,18 @@ 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 {
+func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, conn net.Conn, input *bytes.Reader, rawInput *bytes.Buffer, trafficState *proxy.TrafficState, ob *session.Outbound, ctx context.Context) error {
 	err := func() error {
 		for {
 			if trafficState.ReaderSwitchToDirectCopy {
 				var writerConn net.Conn
-				if inbound := session.InboundFromContext(ctx); inbound != nil && inbound.Conn != nil {
+				if inbound := session.InboundFromContext(ctx); inbound != nil && inbound.Conn != nil && ob != nil {
 					writerConn = inbound.Conn
 					if inbound.CanSpliceCopy == 2 {
-						inbound.CanSpliceCopy = 1 // force the value to 1, don't use setter
+						inbound.CanSpliceCopy = 1
+					}
+					if ob.CanSpliceCopy == 2 { // ob need to be passed in due to context can change
+						ob.CanSpliceCopy = 1
 					}
 				}
 				return proxy.CopyRawConnIfExist(ctx, conn, writerConn, writer, timer)
@@ -219,14 +222,19 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
 }
 
 // XtlsWrite filter and write xtls protocol
-func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, conn net.Conn, trafficState *proxy.TrafficState, ctx context.Context) error {
+func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, conn net.Conn, trafficState *proxy.TrafficState, ob *session.Outbound, ctx context.Context) error {
 	err := func() error {
 		var ct stats.Counter
 		for {
 			buffer, err := reader.ReadMultiBuffer()
 			if trafficState.WriterSwitchToDirectCopy {
-				if inbound := session.InboundFromContext(ctx); inbound != nil && inbound.CanSpliceCopy == 2 {
-					inbound.CanSpliceCopy = 1 // force the value to 1, don't use setter
+				if inbound := session.InboundFromContext(ctx); inbound != nil && ob != nil {
+					if inbound.CanSpliceCopy == 2 {
+						inbound.CanSpliceCopy = 1
+					}
+					if ob.CanSpliceCopy == 2 {
+						ob.CanSpliceCopy = 1
+					}
 				}
 				rawConn, _, writerCounter := proxy.UnwrapRawConn(conn)
 				writer = buf.NewWriter(rawConn)

proxy/vless/inbound/inbound.go

@@ -449,7 +449,7 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
 	switch requestAddons.Flow {
 	case vless.XRV:
 		if account.Flow == requestAddons.Flow {
-			inbound.SetCanSpliceCopy(2)
+			inbound.CanSpliceCopy = 2
 			switch request.Command {
 			case protocol.RequestCommandUDP:
 				return newError(requestAddons.Flow + " doesn't support UDP").AtWarning()
@@ -479,7 +479,7 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
 			return newError(account.ID.String() + " is not able to use " + requestAddons.Flow).AtWarning()
 		}
 	case "":
-		inbound.SetCanSpliceCopy(3)
+		inbound.CanSpliceCopy = 3
 		if account.Flow == vless.XRV && (request.Command == protocol.RequestCommandTCP || isMuxAndNotXUDP(request, first)) {
 			return newError(account.ID.String() + " is not able to use \"\". Note that the pure TLS proxy has certain TLS in TLS characters.").AtWarning()
 		}
@@ -523,7 +523,7 @@ 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)
+			err = encoding.XtlsRead(clientReader, serverWriter, timer, connection, input, rawInput, trafficState, nil, ctx1)
 		} else {
 			// from clientReader.ReadMultiBuffer to serverWriter.WriteMultiBufer
 			err = buf.Copy(clientReader, serverWriter, buf.UpdateActivity(timer))
@@ -560,7 +560,9 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
 
 		var err error
 		if requestAddons.Flow == vless.XRV {
-			err = encoding.XtlsWrite(serverReader, clientWriter, timer, connection, trafficState, ctx)
+			outbounds := session.OutboundsFromContext(ctx)
+			ob := outbounds[len(outbounds) - 1]
+			err = encoding.XtlsWrite(serverReader, clientWriter, timer, connection, trafficState, ob, ctx)
 		} else {
 			// from serverReader.ReadMultiBuffer to clientWriter.WriteMultiBufer
 			err = buf.Copy(serverReader, clientWriter, buf.UpdateActivity(timer))

proxy/vless/outbound/outbound.go

@@ -70,12 +70,12 @@ func New(ctx context.Context, config *Config) (*Handler, error) {
 
 // Process implements proxy.Outbound.Process().
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified").AtError()
 	}
-	outbound.Name = "vless"
-	inbound := session.InboundFromContext(ctx)
+	ob.Name = "vless"
 
 	var rec *protocol.ServerSpec
 	var conn stat.Connection
@@ -96,7 +96,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 	if statConn, ok := iConn.(*stat.CounterConnection); ok {
 		iConn = statConn.Connection
 	}
-	target := outbound.Target
+	target := ob.Target
 	newError("tunneling request to ", target, " via ", rec.Destination().NetAddr()).AtInfo().WriteToLog(session.ExportIDToError(ctx))
 
 	command := protocol.RequestCommandTCP
@@ -130,9 +130,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 		requestAddons.Flow = requestAddons.Flow[:16]
 		fallthrough
 	case vless.XRV:
-		if inbound != nil {
-			inbound.SetCanSpliceCopy(2)
-		}
+		ob.CanSpliceCopy = 2
 		switch request.Command {
 		case protocol.RequestCommandUDP:
 			if !allowUDP443 && request.Port == 443 {
@@ -161,9 +159,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 			rawInput = (*bytes.Buffer)(unsafe.Pointer(p + r.Offset))
 		}
 	default:
-		if inbound != nil {
-			inbound.SetCanSpliceCopy(3)
-		}
+		ob.CanSpliceCopy = 3
 	}
 
 	var newCtx context.Context
@@ -238,8 +234,8 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 					return newError(`failed to use `+requestAddons.Flow+`, found outer tls version `, utlsConn.ConnectionState().Version).AtWarning()
 				}
 			}
-			ctx1 := session.ContextWithOutbound(ctx, nil) // TODO enable splice
-			err = encoding.XtlsWrite(clientReader, serverWriter, timer, conn, trafficState, ctx1)
+			ctx1 := session.ContextWithInbound(ctx, nil) // TODO enable splice
+			err = encoding.XtlsWrite(clientReader, serverWriter, timer, conn, trafficState, ob, ctx1)
 		} else {
 			// from clientReader.ReadMultiBuffer to serverWriter.WriteMultiBufer
 			err = buf.Copy(clientReader, serverWriter, buf.UpdateActivity(timer))
@@ -277,7 +273,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 		}
 
 		if requestAddons.Flow == vless.XRV {
-			err = encoding.XtlsRead(serverReader, clientWriter, timer, conn, input, rawInput, trafficState, ctx)
+			err = encoding.XtlsRead(serverReader, clientWriter, timer, conn, input, rawInput, trafficState, ob, ctx)
 		} else {
 			// from serverReader.ReadMultiBuffer to clientWriter.WriteMultiBufer
 			err = buf.Copy(serverReader, clientWriter, buf.UpdateActivity(timer))

proxy/vmess/inbound/inbound.go

@@ -257,7 +257,7 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
 
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "vmess"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
 	inbound.User = request.User
 
 	sessionPolicy = h.policyManager.ForLevel(request.User.Level)

proxy/vmess/outbound/outbound.go

@@ -60,15 +60,13 @@ func New(ctx context.Context, config *Config) (*Handler, error) {
 
 // Process implements proxy.Outbound.Process().
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified").AtError()
 	}
-	outbound.Name = "vmess"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(3)
-	}
+	ob.Name = "vmess"
+	ob.CanSpliceCopy = 3
 
 	var rec *protocol.ServerSpec
 	var conn stat.Connection
@@ -87,7 +85,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 	}
 	defer conn.Close()
 
-	target := outbound.Target
+	target := ob.Target
 	newError("tunneling request to ", target, " via ", rec.Destination().NetAddr()).WriteToLog(session.ExportIDToError(ctx))
 
 	command := protocol.RequestCommandTCP

proxy/wireguard/client.go

@@ -127,22 +127,20 @@ func (h *Handler) processWireGuard(dialer internet.Dialer) (err error) {
 
 // Process implements OutboundHandler.Dispatch().
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
+	if !ob.Target.IsValid() {
 		return newError("target not specified")
 	}
-	outbound.Name = "wireguard"
-	inbound := session.InboundFromContext(ctx)
-	if inbound != nil {
-		inbound.SetCanSpliceCopy(3)
-	}
+	ob.Name = "wireguard"
+	ob.CanSpliceCopy = 3
 
 	if err := h.processWireGuard(dialer); err != nil {
 		return err
 	}
 
 	// Destination of the inner request.
-	destination := outbound.Target
+	destination := ob.Target
 	command := protocol.RequestCommandTCP
 	if destination.Network == net.Network_UDP {
 		command = protocol.RequestCommandUDP

proxy/wireguard/server.go

@@ -79,13 +79,15 @@ func (*Server) Network() []net.Network {
 func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Connection, dispatcher routing.Dispatcher) error {
 	inbound := session.InboundFromContext(ctx)
 	inbound.Name = "wireguard"
-	inbound.SetCanSpliceCopy(3)
+	inbound.CanSpliceCopy = 3
+	outbounds := session.OutboundsFromContext(ctx)
+	ob := outbounds[len(outbounds) - 1]
 
 	s.info = routingInfo{
 		ctx:         core.ToBackgroundDetachedContext(ctx),
 		dispatcher:  dispatcher,
 		inboundTag:  session.InboundFromContext(ctx),
-		outboundTag: session.OutboundFromContext(ctx),
+		outboundTag: ob,
 		contentTag:  session.ContentFromContext(ctx),
 	}
 
@@ -145,7 +147,7 @@ func (s *Server) forwardConnection(dest net.Destination, conn net.Conn) {
 		ctx = session.ContextWithInbound(ctx, s.info.inboundTag)
 	}
 	if s.info.outboundTag != nil {
-		ctx = session.ContextWithOutbound(ctx, s.info.outboundTag)
+		ctx = session.ContextWithOutbounds(ctx, []*session.Outbound{s.info.outboundTag})
 	}
 	if s.info.contentTag != nil {
 		ctx = session.ContextWithContent(ctx, s.info.contentTag)

transport/internet/dialer.go

@@ -112,7 +112,12 @@ func canLookupIP(ctx context.Context, dst net.Destination, sockopt *SocketConfig
 func redirect(ctx context.Context, dst net.Destination, obt string) net.Conn {
 	newError("redirecting request " + dst.String() + " to " + obt).WriteToLog(session.ExportIDToError(ctx))
 	h := obm.GetHandler(obt)
-	ctx = session.ContextWithOutbound(ctx, &session.Outbound{Target: dst, Gateway: nil})
+	outbounds := session.OutboundsFromContext(ctx)
+    ctx = session.ContextWithOutbounds(ctx, append(outbounds, &session.Outbound{
+		Target: dst, 
+		Gateway: nil,
+		Tag: obt,
+	})) // add another outbound in session ctx
 	if h != nil {
 		ur, uw := pipe.New(pipe.OptionsFromContext(ctx)...)
 		dr, dw := pipe.New(pipe.OptionsFromContext(ctx)...)
@@ -131,8 +136,10 @@ func redirect(ctx context.Context, dst net.Destination, obt string) net.Conn {
 // DialSystem calls system dialer to create a network connection.
 func DialSystem(ctx context.Context, dest net.Destination, sockopt *SocketConfig) (net.Conn, error) {
 	var src net.Address
-	if outbound := session.OutboundFromContext(ctx); outbound != nil {
-		src = outbound.Gateway
+	outbounds := session.OutboundsFromContext(ctx)
+	if len(outbounds) > 0 {
+		ob := outbounds[len(outbounds) - 1]
+		src = ob.Gateway
 	}
 	if sockopt == nil {
 		return effectiveSystemDialer.Dial(ctx, src, dest, sockopt)

transport/internet/grpc/dial.go

@@ -118,7 +118,7 @@ func getGrpcClient(ctx context.Context, dest net.Destination, streamSettings *in
 			address := net.ParseAddress(rawHost)
 
 			gctx = session.ContextWithID(gctx, session.IDFromContext(ctx))
-			gctx = session.ContextWithOutbound(gctx, session.OutboundFromContext(ctx))
+			gctx = session.ContextWithOutbounds(gctx, session.OutboundsFromContext(ctx))
 			gctx = session.ContextWithTimeoutOnly(gctx, true)
 
 			c, err := internet.DialSystem(gctx, net.TCPDestination(address, port), sockopt)

transport/internet/http/dialer.go

@@ -68,7 +68,7 @@ func getHTTPClient(ctx context.Context, dest net.Destination, streamSettings *in
 			address := net.ParseAddress(rawHost)
 
 			hctx = session.ContextWithID(hctx, session.IDFromContext(ctx))
-			hctx = session.ContextWithOutbound(hctx, session.OutboundFromContext(ctx))
+			hctx = session.ContextWithOutbounds(hctx, session.OutboundsFromContext(ctx))
 			hctx = session.ContextWithTimeoutOnly(hctx, true)
 
 			pconn, err := internet.DialSystem(hctx, net.TCPDestination(address, port), sockopt)