fix: fix Fakedns xUDP destination override

app/mydispatcher/default.go

@@ -95,7 +95,8 @@ type DefaultDispatcher struct {
 	router      routing.Router
 	policy      policy.Manager
 	stats       stats.Manager
-	hosts       dns.HostsLookup
+	dns         dns.Client
+	fdns        dns.FakeDNSEngine
 	Limiter     *limiter.Limiter
 	RuleManager *rule.RuleManager
 }
@@ -104,6 +105,9 @@ func init() {
 	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		d := new(DefaultDispatcher)
 		if err := core.RequireFeatures(ctx, func(om outbound.Manager, router routing.Router, pm policy.Manager, sm stats.Manager, dc dns.Client) error {
+			core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
+				d.fdns = fdns
+			})
 			return d.Init(config.(*Config), om, router, pm, sm, dc)
 		}); err != nil {
 			return nil, err
@@ -113,16 +117,14 @@ func init() {
 }
 
 // Init initializes DefaultDispatcher.
-func (d *DefaultDispatcher) Init(config *Config, om outbound.Manager, router routing.Router, pm policy.Manager, sm stats.Manager, dc dns.Client) error {
+func (d *DefaultDispatcher) Init(config *Config, om outbound.Manager, router routing.Router, pm policy.Manager, sm stats.Manager, dns dns.Client) error {
 	d.ohm = om
 	d.router = router
 	d.policy = pm
 	d.stats = sm
 	d.Limiter = limiter.New()
 	d.RuleManager = rule.New()
-	if hosts, ok := dc.(dns.HostsLookup); ok {
+	d.dns = dns
-		d.hosts = hosts
-	}
 	return nil
 }
 
@@ -139,10 +141,77 @@ func (*DefaultDispatcher) Start() error {
 // Close implements common.Closable.
 func (*DefaultDispatcher) Close() error { return nil }
 
-func (d *DefaultDispatcher) getLink(ctx context.Context) (*transport.Link, *transport.Link, error) {
+func (d *DefaultDispatcher) getLink(ctx context.Context, network net.Network, sniffing session.SniffingRequest) (*transport.Link, *transport.Link, error) {
-	opt := pipe.OptionsFromContext(ctx)
+	downOpt := pipe.OptionsFromContext(ctx)
-	uplinkReader, uplinkWriter := pipe.New(opt...)
+	upOpt := downOpt
-	downlinkReader, downlinkWriter := pipe.New(opt...)
+
+	if network == net.Network_UDP {
+		var ip2domain *sync.Map // net.IP.String() => domain, this map is used by server side when client turn on fakedns
+		// Client will send domain address in the buffer.UDP.Address, server record all possible target IP addrs.
+		// When target replies, server will restore the domain and send back to client.
+		// Note: this map is not global but per connection context
+		upOpt = append(upOpt, pipe.OnTransmission(func(mb buf.MultiBuffer) buf.MultiBuffer {
+			for i, buffer := range mb {
+				if buffer.UDP == nil {
+					continue
+				}
+				addr := buffer.UDP.Address
+				if addr.Family().IsIP() {
+					if fkr0, ok := d.fdns.(dns.FakeDNSEngineRev0); ok && fkr0.IsIPInIPPool(addr) && sniffing.Enabled {
+						domain := fkr0.GetDomainFromFakeDNS(addr)
+						if len(domain) > 0 {
+							buffer.UDP.Address = net.DomainAddress(domain)
+							newError("[fakedns client] override with domain: ", domain, " for xUDP buffer at ", i).WriteToLog(session.ExportIDToError(ctx))
+						} else {
+							newError("[fakedns client] failed to find domain! :", addr.String(), " for xUDP buffer at ", i).AtWarning().WriteToLog(session.ExportIDToError(ctx))
+						}
+					}
+				} else {
+					if ip2domain == nil {
+						ip2domain = new(sync.Map)
+						newError("[fakedns client] create a new map").WriteToLog(session.ExportIDToError(ctx))
+					}
+					domain := addr.Domain()
+					ips, err := d.dns.LookupIP(domain, dns.IPOption{true, true, false})
+					if err == nil {
+						for _, ip := range ips {
+							ip2domain.Store(ip.String(), domain)
+						}
+						newError("[fakedns client] candidate ip: "+fmt.Sprintf("%v", ips), " for xUDP buffer at ", i).WriteToLog(session.ExportIDToError(ctx))
+					} else {
+						newError("[fakedns client] failed to look up IP for ", domain, " for xUDP buffer at ", i).Base(err).WriteToLog(session.ExportIDToError(ctx))
+					}
+				}
+			}
+			return mb
+		}))
+		downOpt = append(downOpt, pipe.OnTransmission(func(mb buf.MultiBuffer) buf.MultiBuffer {
+			for i, buffer := range mb {
+				if buffer.UDP == nil {
+					continue
+				}
+				addr := buffer.UDP.Address
+				if addr.Family().IsIP() {
+					if ip2domain == nil {
+						continue
+					}
+					if domain, found := ip2domain.Load(addr.IP().String()); found {
+						buffer.UDP.Address = net.DomainAddress(domain.(string))
+						newError("[fakedns client] restore domain: ", domain.(string), " for xUDP buffer at ", i).WriteToLog(session.ExportIDToError(ctx))
+					}
+				} else {
+					if fkr0, ok := d.fdns.(dns.FakeDNSEngineRev0); ok {
+						fakeIp := fkr0.GetFakeIPForDomain(addr.Domain())
+						buffer.UDP.Address = fakeIp[0]
+						newError("[fakedns client] restore FakeIP: ", buffer.UDP, fmt.Sprintf("%v", fakeIp), " for xUDP buffer at ", i).WriteToLog(session.ExportIDToError(ctx))
+					}
+				}
+			}
+			return mb
+		}))
+	}
+	uplinkReader, uplinkWriter := pipe.New(upOpt...)
+	downlinkReader, downlinkWriter := pipe.New(downOpt...)
 
 	inboundLink := &transport.Link{
 		Reader: downlinkReader,
@@ -199,17 +268,13 @@ func (d *DefaultDispatcher) getLink(ctx context.Context) (*transport.Link, *tran
 	return inboundLink, outboundLink, nil
 }
 
-func shouldOverride(ctx context.Context, result SniffResult, request session.SniffingRequest, destination net.Destination) bool {
+func (d *DefaultDispatcher) shouldOverride(ctx context.Context, result SniffResult, request session.SniffingRequest, destination net.Destination) bool {
 	domain := result.Domain()
 	for _, d := range request.ExcludeForDomain {
 		if strings.ToLower(domain) == d {
 			return false
 		}
 	}
-	var fakeDNSEngine dns.FakeDNSEngine
-	core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
-		fakeDNSEngine = fdns
-	})
 	protocolString := result.Protocol()
 	if resComp, ok := result.(SnifferResultComposite); ok {
 		protocolString = resComp.ProtocolForDomainResult()
@@ -218,7 +283,7 @@ func shouldOverride(ctx context.Context, result SniffResult, request session.Sni
 		if strings.HasPrefix(protocolString, p) {
 			return true
 		}
-		if fkr0, ok := fakeDNSEngine.(dns.FakeDNSEngineRev0); ok && protocolString != "bittorrent" && p == "fakedns" &&
+		if fkr0, ok := d.fdns.(dns.FakeDNSEngineRev0); ok && protocolString != "bittorrent" && p == "fakedns" &&
 			destination.Address.Family().IsIP() && fkr0.IsIPInIPPool(destination.Address) {
 			newError("Using sniffer ", protocolString, " since the fake DNS missed").WriteToLog(session.ExportIDToError(ctx))
 			return true
@@ -242,17 +307,17 @@ func (d *DefaultDispatcher) Dispatch(ctx context.Context, destination net.Destin
 		Target: destination,
 	}
 	ctx = session.ContextWithOutbound(ctx, ob)
-
-	inbound, outbound, err := d.getLink(ctx)
-	if err != nil {
-		return nil, err
-	}
 	content := session.ContentFromContext(ctx)
 	if content == nil {
 		content = new(session.Content)
 		ctx = session.ContextWithContent(ctx, content)
 	}
+
 	sniffingRequest := content.SniffingRequest
+	inbound, outbound, err := d.getLink(ctx, destination.Network, sniffingRequest)
+	if err != nil {
+		return nil, err
+	}
 	switch {
 	case !sniffingRequest.Enabled:
 		go d.routedDispatch(ctx, outbound, destination)
@@ -261,7 +326,7 @@ func (d *DefaultDispatcher) Dispatch(ctx context.Context, destination net.Destin
 		result, err := sniffer(ctx, nil, true)
 		if err == nil {
 			content.Protocol = result.Protocol()
-			if shouldOverride(ctx, result, sniffingRequest, destination) {
+			if d.shouldOverride(ctx, result, sniffingRequest, destination) {
 				domain := result.Domain()
 				newError("sniffed domain: ", domain).WriteToLog(session.ExportIDToError(ctx))
 				destination.Address = net.ParseAddress(domain)
@@ -283,7 +348,7 @@ func (d *DefaultDispatcher) Dispatch(ctx context.Context, destination net.Destin
 			if err == nil {
 				content.Protocol = result.Protocol()
 			}
-			if err == nil && shouldOverride(ctx, result, sniffingRequest, destination) {
+			if err == nil && d.shouldOverride(ctx, result, sniffingRequest, destination) {
 				domain := result.Domain()
 				newError("sniffed domain: ", domain).WriteToLog(session.ExportIDToError(ctx))
 				destination.Address = net.ParseAddress(domain)
@@ -322,7 +387,7 @@ func (d *DefaultDispatcher) DispatchLink(ctx context.Context, destination net.De
 		result, err := sniffer(ctx, nil, true)
 		if err == nil {
 			content.Protocol = result.Protocol()
-			if shouldOverride(ctx, result, sniffingRequest, destination) {
+			if d.shouldOverride(ctx, result, sniffingRequest, destination) {
 				domain := result.Domain()
 				newError("sniffed domain: ", domain).WriteToLog(session.ExportIDToError(ctx))
 				destination.Address = net.ParseAddress(domain)
@@ -344,7 +409,7 @@ func (d *DefaultDispatcher) DispatchLink(ctx context.Context, destination net.De
 			if err == nil {
 				content.Protocol = result.Protocol()
 			}
-			if err == nil && shouldOverride(ctx, result, sniffingRequest, destination) {
+			if err == nil && d.shouldOverride(ctx, result, sniffingRequest, destination) {
 				domain := result.Domain()
 				newError("sniffed domain: ", domain).WriteToLog(session.ExportIDToError(ctx))
 				destination.Address = net.ParseAddress(domain)
@@ -408,8 +473,8 @@ func sniffer(ctx context.Context, cReader *cachedReader, metadataOnly bool) (Sni
 
 func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.Link, destination net.Destination) {
 	ob := session.OutboundFromContext(ctx)
-	if d.hosts != nil && destination.Address.Family().IsDomain() {
+	if hosts, ok := d.dns.(dns.HostsLookup); ok && destination.Address.Family().IsDomain() {
-		proxied := d.hosts.LookupHosts(ob.Target.String())
+		proxied := hosts.LookupHosts(ob.Target.String())
 		if proxied != nil {
 			ro := ob.RouteTarget == destination
 			destination.Address = *proxied
@@ -438,10 +503,11 @@ func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.
 
 	routingLink := routing_session.AsRoutingContext(ctx)
 	inTag := routingLink.GetInboundTag()
-
+	isPickRoute := 0
 	if forcedOutboundTag := session.GetForcedOutboundTagFromContext(ctx); forcedOutboundTag != "" {
 		ctx = session.SetForcedOutboundTagToContext(ctx, "")
 		if h := d.ohm.GetHandler(forcedOutboundTag); h != nil {
+			isPickRoute = 1
 			newError("taking platform initialized detour [", forcedOutboundTag, "] for [", destination, "]").WriteToLog(session.ExportIDToError(ctx))
 			handler = h
 		} else {
@@ -451,13 +517,14 @@ func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.
 			return
 		}
 	} else if d.router != nil {
-		if route, err := d.router.PickRoute(routing_session.AsRoutingContext(ctx)); err == nil {
+		if route, err := d.router.PickRoute(routingLink); err == nil {
-			tag := route.GetOutboundTag()
+			outTag := route.GetOutboundTag()
-			if h := d.ohm.GetHandler(tag); h != nil {
+			if h := d.ohm.GetHandler(outTag); h != nil {
-				newError("taking detour [", tag, "] for [", destination, "]").WriteToLog(session.ExportIDToError(ctx))
+				isPickRoute = 2
+				newError("taking detour [", outTag, "] for [", destination, "]").WriteToLog(session.ExportIDToError(ctx))
 				handler = h
 			} else {
-				newError("non existing outTag: ", tag).AtWarning().WriteToLog(session.ExportIDToError(ctx))
+				newError("non existing outTag: ", outTag).AtWarning().WriteToLog(session.ExportIDToError(ctx))
 			}
 		} else {
 			newError("default route for ", destination).WriteToLog(session.ExportIDToError(ctx))
@@ -482,7 +549,15 @@ func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.
 
 	if accessMessage := log.AccessMessageFromContext(ctx); accessMessage != nil {
 		if tag := handler.Tag(); tag != "" {
+			if inTag == "" {
 				accessMessage.Detour = tag
+			} else if isPickRoute == 1 {
+				accessMessage.Detour = inTag + " ==> " + tag
+			} else if isPickRoute == 2 {
+				accessMessage.Detour = inTag + " -> " + tag
+			} else {
+				accessMessage.Detour = inTag + " >> " + tag
+			}
 		}
 		log.Record(accessMessage)
 	}

app/mydispatcher/fakednssniffer.go

@@ -15,7 +15,7 @@ import (
 func newFakeDNSSniffer(ctx context.Context) (protocolSnifferWithMetadata, error) {
 	var fakeDNSEngine dns.FakeDNSEngine
 	{
-		fakeDNSEngineFeat := core.MustFromContext(ctx).GetFeature(fakeDNSEngine)
+		fakeDNSEngineFeat := core.MustFromContext(ctx).GetFeature((*dns.FakeDNSEngine)(nil))
 		if fakeDNSEngineFeat != nil {
 			fakeDNSEngine = fakeDNSEngineFeat.(dns.FakeDNSEngine)
 		}