Use resolved in local DNS server if available

adapter/outbound/manager.go

@@ -30,7 +30,7 @@ type Manager struct {
 	outboundByTag           map[string]adapter.Outbound
 	dependByTag             map[string][]string
 	defaultOutbound         adapter.Outbound
-	defaultOutboundFallback adapter.Outbound
+	defaultOutboundFallback func() (adapter.Outbound, error)
 }
 
 func NewManager(logger logger.ContextLogger, registry adapter.OutboundRegistry, endpoint adapter.EndpointManager, defaultTag string) *Manager {
@@ -44,7 +44,7 @@ func NewManager(logger logger.ContextLogger, registry adapter.OutboundRegistry,
 	}
 }
 
-func (m *Manager) Initialize(defaultOutboundFallback adapter.Outbound) {
+func (m *Manager) Initialize(defaultOutboundFallback func() (adapter.Outbound, error)) {
 	m.defaultOutboundFallback = defaultOutboundFallback
 }
 
@@ -55,18 +55,31 @@ func (m *Manager) Start(stage adapter.StartStage) error {
 	}
 	m.started = true
 	m.stage = stage
-	outbounds := m.outbounds
-	m.access.Unlock()
 	if stage == adapter.StartStateStart {
+		if m.defaultOutbound == nil {
+			directOutbound, err := m.defaultOutboundFallback()
+			if err != nil {
+				m.access.Unlock()
+				return E.Cause(err, "create direct outbound for fallback")
+			}
+			m.outbounds = append(m.outbounds, directOutbound)
+			m.outboundByTag[directOutbound.Tag()] = directOutbound
+			m.defaultOutbound = directOutbound
+		}
 		if m.defaultTag != "" && m.defaultOutbound == nil {
 			defaultEndpoint, loaded := m.endpoint.Get(m.defaultTag)
 			if !loaded {
+				m.access.Unlock()
 				return E.New("default outbound not found: ", m.defaultTag)
 			}
 			m.defaultOutbound = defaultEndpoint
 		}
+		outbounds := m.outbounds
+		m.access.Unlock()
 		return m.startOutbounds(append(outbounds, common.Map(m.endpoint.Endpoints(), func(it adapter.Endpoint) adapter.Outbound { return it })...))
 	} else {
+		outbounds := m.outbounds
+		m.access.Unlock()
 		for _, outbound := range outbounds {
 			err := adapter.LegacyStart(outbound, stage)
 			if err != nil {
@@ -187,11 +200,7 @@ func (m *Manager) Outbound(tag string) (adapter.Outbound, bool) {
 func (m *Manager) Default() adapter.Outbound {
 	m.access.RLock()
 	defer m.access.RUnlock()
-	if m.defaultOutbound != nil {
-		return m.defaultOutbound
-	} else {
-		return m.defaultOutboundFallback
-	}
+	return m.defaultOutbound
 }
 
 func (m *Manager) Remove(tag string) error {

box.go

@@ -314,15 +314,15 @@ func New(options Options) (*Box, error) {
 			return nil, E.Cause(err, "initialize service[", i, "]")
 		}
 	}
-	outboundManager.Initialize(common.Must1(
-		direct.NewOutbound(
+	outboundManager.Initialize(func() (adapter.Outbound, error) {
+		return direct.NewOutbound(
 			ctx,
 			router,
 			logFactory.NewLogger("outbound/direct"),
 			"direct",
 			option.DirectOutboundOptions{},
-		),
-	))
+		)
+	})
 	dnsTransportManager.Initialize(common.Must1(
 		local.NewTransport(
 			ctx,

dns/transport/local/local.go

@@ -13,6 +13,7 @@ import (
 	"github.com/sagernet/sing-box/option"
 	"github.com/sagernet/sing/common/buf"
 	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 
@@ -23,9 +24,11 @@ var _ adapter.DNSTransport = (*Transport)(nil)
 
 type Transport struct {
 	dns.TransportAdapter
-	ctx    context.Context
-	hosts  *hosts.File
-	dialer N.Dialer
+	ctx      context.Context
+	logger   logger.ContextLogger
+	hosts    *hosts.File
+	dialer   N.Dialer
+	resolved ResolvedResolver
 }
 
 func NewTransport(ctx context.Context, logger log.ContextLogger, tag string, options option.LocalDNSServerOptions) (adapter.DNSTransport, error) {
@@ -36,20 +39,39 @@ func NewTransport(ctx context.Context, logger log.ContextLogger, tag string, opt
 	return &Transport{
 		TransportAdapter: dns.NewTransportAdapterWithLocalOptions(C.DNSTypeLocal, tag, options),
 		ctx:              ctx,
+		logger:           logger,
 		hosts:            hosts.NewFile(hosts.DefaultPath),
 		dialer:           transportDialer,
 	}, nil
 }
 
 func (t *Transport) Start(stage adapter.StartStage) error {
+	switch stage {
+	case adapter.StartStateInitialize:
+		resolvedResolver, err := NewResolvedResolver(t.ctx, t.logger)
+		if err == nil {
+			err = resolvedResolver.Start()
+			if err == nil {
+				t.resolved = resolvedResolver
+			} else {
+				t.logger.Warn(E.Cause(err, "initialize resolved resolver"))
+			}
+		}
+	}
 	return nil
 }
 
 func (t *Transport) Close() error {
+	if t.resolved != nil {
+		return t.resolved.Close()
+	}
 	return nil
 }
 
 func (t *Transport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
+	if t.resolved != nil && t.resolved.Available() {
+		return t.resolved.Exchange(ctx, message)
+	}
 	question := message.Question[0]
 	domain := dns.FqdnToDomain(question.Name)
 	if question.Qtype == mDNS.TypeA || question.Qtype == mDNS.TypeAAAA {

dns/transport/local/local_fallback.go

@@ -33,6 +33,10 @@ func NewFallbackTransport(ctx context.Context, logger log.ContextLogger, tag str
 	if err != nil {
 		return nil, err
 	}
+	platformInterface := service.FromContext[platform.Interface](ctx)
+	if platformInterface == nil {
+		return transport, nil
+	}
 	return &FallbackTransport{
 		DNSTransport: transport,
 		ctx:          ctx,
@@ -40,11 +44,11 @@ func NewFallbackTransport(ctx context.Context, logger log.ContextLogger, tag str
 }
 
 func (f *FallbackTransport) Start(stage adapter.StartStage) error {
-	if stage != adapter.StartStateStart {
-		return nil
+	err := f.DNSTransport.Start(stage)
+	if err != nil {
+		return err
 	}
-	platformInterface := service.FromContext[platform.Interface](f.ctx)
-	if platformInterface == nil {
+	if stage != adapter.StartStatePostStart {
 		return nil
 	}
 	inboundManager := service.FromContext[adapter.InboundManager](f.ctx)
@@ -59,7 +63,7 @@ func (f *FallbackTransport) Start(stage adapter.StartStage) error {
 }
 
 func (f *FallbackTransport) Close() error {
-	return nil
+	return f.DNSTransport.Close()
 }
 
 func (f *FallbackTransport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {

dns/transport/local/local_resolved.go

@@ -0,0 +1,14 @@
+package local
+
+import (
+	"context"
+
+	mDNS "github.com/miekg/dns"
+)
+
+type ResolvedResolver interface {
+	Start() error
+	Close() error
+	Available() bool
+	Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error)
+}

dns/transport/local/local_resolved_linux.go

@@ -0,0 +1,154 @@
+package local
+
+import (
+	"context"
+	"os"
+	"sync"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/service/resolved"
+	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common/atomic"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
+	"github.com/sagernet/sing/service"
+
+	"github.com/godbus/dbus/v5"
+	mDNS "github.com/miekg/dns"
+)
+
+type DBusResolvedResolver struct {
+	logger           logger.ContextLogger
+	interfaceMonitor tun.DefaultInterfaceMonitor
+	systemBus        *dbus.Conn
+	resoledObject    atomic.TypedValue[dbus.BusObject]
+	closeOnce        sync.Once
+}
+
+func NewResolvedResolver(ctx context.Context, logger logger.ContextLogger) (ResolvedResolver, error) {
+	interfaceMonitor := service.FromContext[adapter.NetworkManager](ctx).InterfaceMonitor()
+	if interfaceMonitor == nil {
+		return nil, os.ErrInvalid
+	}
+	systemBus, err := dbus.SystemBus()
+	if err != nil {
+		return nil, err
+	}
+	return &DBusResolvedResolver{
+		logger:           logger,
+		interfaceMonitor: interfaceMonitor,
+		systemBus:        systemBus,
+	}, nil
+}
+
+func (t *DBusResolvedResolver) Start() error {
+	t.updateStatus()
+	err := t.systemBus.BusObject().AddMatchSignal(
+		"org.freedesktop.DBus",
+		"NameOwnerChanged",
+		dbus.WithMatchSender("org.freedesktop.DBus"),
+		dbus.WithMatchArg(0, "org.freedesktop.resolve1.Manager"),
+	).Err
+	if err != nil {
+		return E.Cause(err, "configure resolved restart listener")
+	}
+	go t.loopUpdateStatus()
+	return nil
+}
+
+func (t *DBusResolvedResolver) Close() error {
+	t.closeOnce.Do(func() {
+		if t.systemBus != nil {
+			_ = t.systemBus.Close()
+		}
+	})
+	return nil
+}
+
+func (t *DBusResolvedResolver) Available() bool {
+	return t.resoledObject.Load() == nil
+}
+
+func (t *DBusResolvedResolver) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
+	defaultInterface := t.interfaceMonitor.DefaultInterface()
+	if defaultInterface == nil {
+		return nil, E.New("missing default interface")
+	}
+	resolvedObject := t.resoledObject.Load()
+	if resolvedObject == nil {
+		return nil, E.New("DBus interface for resolved is not available")
+	}
+	question := message.Question[0]
+	call := resolvedObject.CallWithContext(
+		ctx,
+		"org.freedesktop.resolve1.Manager.ResolveRecord",
+		0,
+		int32(defaultInterface.Index),
+		question.Name,
+		question.Qclass,
+		question.Qtype,
+		uint64(0),
+	)
+	if call.Err != nil {
+		return nil, E.Cause(call.Err, " resolve record via resolved")
+	}
+	var (
+		records  []resolved.ResourceRecord
+		outflags uint64
+	)
+	err := call.Store(&records, &outflags)
+	if err != nil {
+		return nil, err
+	}
+	response := &mDNS.Msg{
+		MsgHdr: mDNS.MsgHdr{
+			Id:                 message.Id,
+			Response:           true,
+			Authoritative:      true,
+			RecursionDesired:   true,
+			RecursionAvailable: true,
+			Rcode:              mDNS.RcodeSuccess,
+		},
+		Question: []mDNS.Question{question},
+	}
+	for _, record := range records {
+		var rr mDNS.RR
+		rr, _, err = mDNS.UnpackRR(record.Data, 0)
+		if err != nil {
+			return nil, E.Cause(err, "unpack resource record")
+		}
+		response.Answer = append(response.Answer, rr)
+	}
+	return response, nil
+}
+
+func (t *DBusResolvedResolver) loopUpdateStatus() {
+	signalChan := make(chan *dbus.Signal, 1)
+	t.systemBus.Signal(signalChan)
+	for signal := range signalChan {
+		var restarted bool
+		if signal.Name == "org.freedesktop.DBus.NameOwnerChanged" {
+			if len(signal.Body) != 3 || signal.Body[2].(string) == "" {
+				continue
+			} else {
+				restarted = true
+			}
+		}
+		if restarted {
+			t.updateStatus()
+		}
+	}
+}
+
+func (t *DBusResolvedResolver) updateStatus() {
+	dbusObject := t.systemBus.Object("org.freedesktop.resolve1", "/org/freedesktop/resolve1")
+	err := dbusObject.Call("org.freedesktop.DBus.Peer.Ping", 0).Err
+	if err != nil {
+		if t.resoledObject.Swap(nil) != nil {
+			t.logger.Debug("systemd-resolved service is gone")
+		}
+		return
+	}
+	t.resoledObject.Store(dbusObject)
+	t.logger.Debug("using systemd-resolved service as resolver")
+}

dns/transport/local/local_resolved_stub.go

@@ -0,0 +1,14 @@
+//go:build !linux
+
+package local
+
+import (
+	"context"
+	"os"
+
+	"github.com/sagernet/sing/common/logger"
+)
+
+func NewResolvedResolver(ctx context.Context, logger logger.ContextLogger) (ResolvedResolver, error) {
+	return nil, os.ErrInvalid
+}

service/resolved/resolve1.go

@@ -182,9 +182,9 @@ func (t *resolve1Manager) logRequest(sender dbus.Sender, message ...any) context
 		} else if metadata.ProcessInfo.UserId != 0 {
 			prefix = F.ToString("uid:", metadata.ProcessInfo.UserId)
 		}
-		t.logger.InfoContext(ctx, "(", prefix, ") ", F.ToString(message...))
+		t.logger.InfoContext(ctx, "(", prefix, ") ", strings.Join(F.MapToString(message), " "))
 	} else {
-		t.logger.InfoContext(ctx, F.ToString(message...))
+		t.logger.InfoContext(ctx, strings.Join(F.MapToString(message), " "))
 	}
 	return adapter.WithContext(ctx, &metadata)
 }
@@ -280,7 +280,10 @@ func (t *resolve1Manager) ResolveAddress(sender dbus.Sender, ifIndex int32, fami
 		},
 	}
 	ctx := t.logRequest(sender, "ResolveAddress ", link.iif.Name, familyToString(family), addr, flags)
-	response, lookupErr := t.dnsRouter.Exchange(ctx, request, adapter.DNSQueryOptions{})
+	var metadata adapter.InboundContext
+	metadata.InboundType = t.Type()
+	metadata.Inbound = t.Tag()
+	response, lookupErr := t.dnsRouter.Exchange(adapter.WithContext(ctx, &metadata), request, adapter.DNSQueryOptions{})
 	if lookupErr != nil {
 		err = wrapError(err)
 		return
@@ -301,7 +304,7 @@ func (t *resolve1Manager) ResolveAddress(sender dbus.Sender, ifIndex int32, fami
 	return
 }
 
-func (t *resolve1Manager) ResolveRecord(sender dbus.Sender, ifIndex int32, family int32, hostname string, qClass uint16, qType uint16, flags uint64) (records []ResourceRecord, outflags uint64, err *dbus.Error) {
+func (t *resolve1Manager) ResolveRecord(sender dbus.Sender, ifIndex int32, hostname string, qClass uint16, qType uint16, flags uint64) (records []ResourceRecord, outflags uint64, err *dbus.Error) {
 	t.linkAccess.Lock()
 	link, err := t.getLink(ifIndex)
 	if err != nil {
@@ -320,8 +323,11 @@ func (t *resolve1Manager) ResolveRecord(sender dbus.Sender, ifIndex int32, famil
 			},
 		},
 	}
-	ctx := t.logRequest(sender, "ResolveRecord ", link.iif.Name, familyToString(family), hostname, mDNS.Class(qClass), mDNS.Type(qType), flags)
-	response, exchangeErr := t.dnsRouter.Exchange(ctx, request, adapter.DNSQueryOptions{})
+	ctx := t.logRequest(sender, "ResolveRecord", link.iif.Name, hostname, mDNS.Class(qClass), mDNS.Type(qType), flags)
+	var metadata adapter.InboundContext
+	metadata.InboundType = t.Type()
+	metadata.Inbound = t.Tag()
+	response, exchangeErr := t.dnsRouter.Exchange(adapter.WithContext(ctx, &metadata), request, adapter.DNSQueryOptions{})
 	if exchangeErr != nil {
 		err = wrapError(exchangeErr)
 		return
@@ -341,6 +347,7 @@ func (t *resolve1Manager) ResolveRecord(sender dbus.Sender, ifIndex int32, famil
 			err = wrapError(unpackErr)
 		}
 		record.Data = data
+		records = append(records, record)
 	}
 	return
 }
@@ -380,8 +387,10 @@ func (t *resolve1Manager) ResolveService(sender dbus.Sender, ifIndex int32, host
 			},
 		},
 	}
-
-	srvResponse, exchangeErr := t.dnsRouter.Exchange(ctx, srvRequest, adapter.DNSQueryOptions{})
+	var metadata adapter.InboundContext
+	metadata.InboundType = t.Type()
+	metadata.Inbound = t.Tag()
+	srvResponse, exchangeErr := t.dnsRouter.Exchange(adapter.WithContext(ctx, &metadata), srvRequest, adapter.DNSQueryOptions{})
 	if exchangeErr != nil {
 		err = wrapError(exchangeErr)
 		return

service/resolved/service.go

@@ -91,11 +91,6 @@ func (i *Service) Start(stage adapter.StartStage) error {
 				return E.New("multiple resolved service are not supported")
 			}
 		}
-	case adapter.StartStateStart:
-		err := i.listener.Start()
-		if err != nil {
-			return err
-		}
 		systemBus, err := dbus.SystemBus()
 		if err != nil {
 			return err
@@ -117,6 +112,11 @@ func (i *Service) Start(stage adapter.StartStage) error {
 			return E.New("unknown request name reply: ", reply)
 		}
 		i.networkUpdateCallback = i.network.NetworkMonitor().RegisterCallback(i.onNetworkUpdate)
+	case adapter.StartStateStart:
+		err := i.listener.Start()
+		if err != nil {
+			return err
+		}
 	}
 	return nil
 }
@@ -167,6 +167,8 @@ func (i *Service) exchangePacket0(ctx context.Context, buffer *buf.Buffer, oob [
 	}
 	var metadata adapter.InboundContext
 	metadata.Source = source
+	metadata.InboundType = i.Type()
+	metadata.Inbound = i.Tag()
 	response, err := i.dnsRouter.Exchange(adapter.WithContext(ctx, &metadata), &message, adapter.DNSQueryOptions{})
 	if err != nil {
 		return err