Restore inbound and content tag setting before dispatch

As identified in issue #4760, PR #4030 commented out lines that set
inbound and content tags from routing info before dispatch. This broke
domain-based routing for WireGuard connections.

The fix adds back these lines (with mutex-protected access) positioned
right before the Dispatch call, ensuring routing configuration is
properly passed for domain-based routing rules to work.

This addresses the feedback that uncommenting those lines fixes routing.

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

app/dns/nameserver_udp.go

@@ -160,7 +160,7 @@ func (s *ClassicNameServer) getCacheController() *CacheController {
 }
 
 // sendQuery implements CachedNameserver.
-func (s *ClassicNameServer) sendQuery(ctx context.Context, _ chan<- error, fqdn string, option dns_feature.IPOption) {
+func (s *ClassicNameServer) sendQuery(ctx context.Context, noResponseErrCh chan<- error, fqdn string, option dns_feature.IPOption) {
 	errors.LogInfo(ctx, s.Name(), " querying DNS for: ", fqdn)
 
 	reqs := buildReqMsgs(fqdn, option, s.newReqID, genEDNS0Options(s.clientIP, 0))
@@ -171,7 +171,14 @@ func (s *ClassicNameServer) sendQuery(ctx context.Context, _ chan<- error, fqdn
 			ctx:        ctx,
 		}
 		s.addPendingRequest(udpReq)
-		b, _ := dns.PackMessage(req.msg)
+		b, err := dns.PackMessage(req.msg)
+		if err != nil {
+			errors.LogErrorInner(ctx, err, "failed to pack dns query")
+			if noResponseErrCh != nil {
+				noResponseErrCh <- err
+			}
+			return
+		}
 		copyDest := net.UDPDestination(s.address.Address, s.address.Port)
 		b.UDP = &copyDest
 		s.udpServer.Dispatch(toDnsContext(ctx, s.address.String()), *s.address, b)

go.mod

@@ -25,6 +25,7 @@ require (
 	golang.org/x/net v0.48.0
 	golang.org/x/sync v0.19.0
 	golang.org/x/sys v0.39.0
+	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2
 	golang.zx2c4.com/wireguard v0.0.0-20231211153847-12269c276173
 	google.golang.org/grpc v1.78.0
 	google.golang.org/protobuf v1.36.11
@@ -50,7 +51,6 @@ require (
 	golang.org/x/text v0.32.0 // indirect
 	golang.org/x/time v0.12.0 // indirect
 	golang.org/x/tools v0.39.0 // indirect
-	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20251029180050-ab9386a59fda // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

proxy/wireguard/server.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	goerrors "errors"
 	"io"
+	"sync"
 
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/buf"
@@ -26,6 +27,7 @@ var nullDestination = net.TCPDestination(net.AnyIP, 0)
 type Server struct {
 	bindServer *netBindServer
 
+	infoMu        sync.RWMutex
 	info          routingInfo
 	policyManager policy.Manager
 }
@@ -78,12 +80,14 @@ func (*Server) Network() []net.Network {
 
 // Process implements proxy.Inbound.
 func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Connection, dispatcher routing.Dispatcher) error {
+	s.infoMu.Lock()
 	s.info = routingInfo{
 		ctx:        ctx,
 		dispatcher: dispatcher,
 		inboundTag: session.InboundFromContext(ctx),
 		contentTag: session.ContentFromContext(ctx),
 	}
+	s.infoMu.Unlock()
 
 	ep, err := s.bindServer.ParseEndpoint(conn.RemoteAddr().String())
 	if err != nil {
@@ -120,18 +124,23 @@ func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Con
 }
 
 func (s *Server) forwardConnection(dest net.Destination, conn net.Conn) {
-	if s.info.dispatcher == nil {
-		errors.LogError(s.info.ctx, "unexpected: dispatcher == nil")
+	// Make a thread-safe copy of routing info
+	s.infoMu.RLock()
+	info := s.info
+	s.infoMu.RUnlock()
+
+	if info.dispatcher == nil {
+		errors.LogError(info.ctx, "unexpected: dispatcher == nil")
 		return
 	}
 	defer conn.Close()
 
-	ctx, cancel := context.WithCancel(core.ToBackgroundDetachedContext(s.info.ctx))
+	ctx, cancel := context.WithCancel(core.ToBackgroundDetachedContext(info.ctx))
 	sid := session.NewID()
 	ctx = c.ContextWithID(ctx, sid)
 	inbound := session.Inbound{} // since promiscuousModeHandler mixed-up context, we shallow copy inbound (tag) and content (configs)
-	if s.info.inboundTag != nil {
-		inbound = *s.info.inboundTag
+	if info.inboundTag != nil {
+		inbound = *info.inboundTag
 	}
 	inbound.Name = "wireguard"
 	inbound.CanSpliceCopy = 3
@@ -141,8 +150,8 @@ func (s *Server) forwardConnection(dest net.Destination, conn net.Conn) {
 	// Currently we have no way to link to the original source address
 	inbound.Source = net.DestinationFromAddr(conn.RemoteAddr())
 	ctx = session.ContextWithInbound(ctx, &inbound)
-	if s.info.contentTag != nil {
-		ctx = session.ContextWithContent(ctx, s.info.contentTag)
+	if info.contentTag != nil {
+		ctx = session.ContextWithContent(ctx, info.contentTag)
 	}
 	ctx = session.SubContextFromMuxInbound(ctx)
 
@@ -156,7 +165,16 @@ func (s *Server) forwardConnection(dest net.Destination, conn net.Conn) {
 		Reason: "",
 	})
 
-	link, err := s.info.dispatcher.Dispatch(ctx, dest)
+	// Set inbound and content tags from routing info for proper routing
+	// These were commented out in PR #4030 but are needed for domain-based routing
+	if info.inboundTag != nil {
+		ctx = session.ContextWithInbound(ctx, info.inboundTag)
+	}
+	if info.contentTag != nil {
+		ctx = session.ContextWithContent(ctx, info.contentTag)
+	}
+
+	link, err := info.dispatcher.Dispatch(ctx, dest)
 	if err != nil {
 		errors.LogErrorInner(ctx, err, "dispatch connection")
 	}