Add multi network dialing

adapter/inbound.go

@@ -3,8 +3,10 @@ package adapter
 import (
 	"context"
 	"net/netip"
+	"time"
 
 	"github.com/sagernet/sing-box/common/process"
+	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
 	M "github.com/sagernet/sing/common/metadata"
@@ -66,6 +68,8 @@ type InboundContext struct {
 	InboundOptions            option.InboundOptions
 	UDPDisableDomainUnmapping bool
 	UDPConnect                bool
+	NetworkStrategy           C.NetworkStrategy
+	FallbackDelay             time.Duration
 
 	DNSServer string
 

adapter/network.go

@@ -1,6 +1,9 @@
 package adapter
 
 import (
+	"time"
+
+	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-tun"
 	"github.com/sagernet/sing/common/control"
 )
@@ -11,10 +14,10 @@ type NetworkManager interface {
 	UpdateInterfaces() error
 	DefaultNetworkInterface() *NetworkInterface
 	NetworkInterfaces() []NetworkInterface
-	DefaultInterface() string
 	AutoDetectInterface() bool
 	AutoDetectInterfaceFunc() control.Func
-	DefaultMark() uint32
+	ProtectFunc() control.Func
+	DefaultOptions() NetworkOptions
 	RegisterAutoRedirectOutputMark(mark uint32) error
 	AutoRedirectOutputMark() uint32
 	NetworkMonitor() tun.NetworkUpdateMonitor
@@ -24,6 +27,13 @@ type NetworkManager interface {
 	ResetNetwork()
 }
 
+type NetworkOptions struct {
+	DefaultNetworkStrategy C.NetworkStrategy
+	DefaultFallbackDelay   time.Duration
+	DefaultInterface       string
+	DefaultMark            uint32
+}
+
 type InterfaceUpdateListener interface {
 	InterfaceUpdated()
 }

adapter/outbound/default.go

@@ -8,8 +8,8 @@ import (
 	"time"
 
 	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/dialer"
 	C "github.com/sagernet/sing-box/constant"
-	"github.com/sagernet/sing-dns"
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
 	"github.com/sagernet/sing/common/bufio"
@@ -25,35 +25,11 @@ func NewConnection(ctx context.Context, this N.Dialer, conn net.Conn, metadata a
 	var outConn net.Conn
 	var err error
 	if len(metadata.DestinationAddresses) > 0 {
-		outConn, err = N.DialSerial(ctx, this, N.NetworkTCP, metadata.Destination, metadata.DestinationAddresses)
+		if parallelDialer, isParallelDialer := this.(dialer.ParallelInterfaceDialer); isParallelDialer {
+			outConn, err = dialer.DialSerialNetwork(ctx, parallelDialer, N.NetworkTCP, metadata.Destination, metadata.DestinationAddresses, metadata.NetworkStrategy, metadata.FallbackDelay)
 		} else {
-		outConn, err = this.DialContext(ctx, N.NetworkTCP, metadata.Destination)
-	}
-	if err != nil {
-		return N.ReportHandshakeFailure(conn, err)
-	}
-	err = N.ReportConnHandshakeSuccess(conn, outConn)
-	if err != nil {
-		outConn.Close()
-		return err
-	}
-	return CopyEarlyConn(ctx, conn, outConn)
-}
-
-func NewDirectConnection(ctx context.Context, router adapter.Router, this N.Dialer, conn net.Conn, metadata adapter.InboundContext, domainStrategy dns.DomainStrategy) error {
-	defer conn.Close()
-	ctx = adapter.WithContext(ctx, &metadata)
-	var outConn net.Conn
-	var err error
-	if len(metadata.DestinationAddresses) > 0 {
 			outConn, err = N.DialSerial(ctx, this, N.NetworkTCP, metadata.Destination, metadata.DestinationAddresses)
-	} else if metadata.Destination.IsFqdn() {
-		var destinationAddresses []netip.Addr
-		destinationAddresses, err = router.Lookup(ctx, metadata.Destination.Fqdn, domainStrategy)
-		if err != nil {
-			return N.ReportHandshakeFailure(conn, err)
 		}
-		outConn, err = N.DialSerial(ctx, this, N.NetworkTCP, metadata.Destination, destinationAddresses)
 	} else {
 		outConn, err = this.DialContext(ctx, N.NetworkTCP, metadata.Destination)
 	}
@@ -79,7 +55,11 @@ func NewPacketConnection(ctx context.Context, this N.Dialer, conn N.PacketConn,
 	)
 	if metadata.UDPConnect {
 		if len(metadata.DestinationAddresses) > 0 {
+			if parallelDialer, isParallelDialer := this.(dialer.ParallelInterfaceDialer); isParallelDialer {
+				outConn, err = dialer.DialSerialNetwork(ctx, parallelDialer, N.NetworkUDP, metadata.Destination, metadata.DestinationAddresses, metadata.NetworkStrategy, metadata.FallbackDelay)
+			} else {
 				outConn, err = N.DialSerial(ctx, this, N.NetworkUDP, metadata.Destination, metadata.DestinationAddresses)
+			}
 		} else {
 			outConn, err = this.DialContext(ctx, N.NetworkUDP, metadata.Destination)
 		}
@@ -93,7 +73,11 @@ func NewPacketConnection(ctx context.Context, this N.Dialer, conn N.PacketConn,
 		}
 	} else {
 		if len(metadata.DestinationAddresses) > 0 {
+			if parallelDialer, isParallelDialer := this.(dialer.ParallelInterfaceDialer); isParallelDialer {
+				outPacketConn, destinationAddress, err = dialer.ListenSerialNetworkPacket(ctx, parallelDialer, metadata.Destination, metadata.DestinationAddresses, metadata.NetworkStrategy, metadata.FallbackDelay)
+			} else {
 				outPacketConn, destinationAddress, err = N.ListenSerial(ctx, this, metadata.Destination, metadata.DestinationAddresses)
+			}
 		} else {
 			outPacketConn, err = this.ListenPacket(ctx, metadata.Destination)
 		}
@@ -129,76 +113,6 @@ func NewPacketConnection(ctx context.Context, this N.Dialer, conn N.PacketConn,
 	return bufio.CopyPacketConn(ctx, conn, bufio.NewPacketConn(outPacketConn))
 }
 
-func NewDirectPacketConnection(ctx context.Context, router adapter.Router, this N.Dialer, conn N.PacketConn, metadata adapter.InboundContext, domainStrategy dns.DomainStrategy) error {
-	defer conn.Close()
-	ctx = adapter.WithContext(ctx, &metadata)
-	var (
-		outPacketConn      net.PacketConn
-		outConn            net.Conn
-		destinationAddress netip.Addr
-		err                error
-	)
-	if metadata.UDPConnect {
-		if len(metadata.DestinationAddresses) > 0 {
-			outConn, err = N.DialSerial(ctx, this, N.NetworkUDP, metadata.Destination, metadata.DestinationAddresses)
-		} else if metadata.Destination.IsFqdn() {
-			var destinationAddresses []netip.Addr
-			destinationAddresses, err = router.Lookup(ctx, metadata.Destination.Fqdn, domainStrategy)
-			if err != nil {
-				return N.ReportHandshakeFailure(conn, err)
-			}
-			outConn, err = N.DialSerial(ctx, this, N.NetworkUDP, metadata.Destination, destinationAddresses)
-		} else {
-			outConn, err = this.DialContext(ctx, N.NetworkUDP, metadata.Destination)
-		}
-		if err != nil {
-			return N.ReportHandshakeFailure(conn, err)
-		}
-		connRemoteAddr := M.AddrFromNet(outConn.RemoteAddr())
-		if connRemoteAddr != metadata.Destination.Addr {
-			destinationAddress = connRemoteAddr
-		}
-	} else {
-		if len(metadata.DestinationAddresses) > 0 {
-			outPacketConn, destinationAddress, err = N.ListenSerial(ctx, this, metadata.Destination, metadata.DestinationAddresses)
-		} else if metadata.Destination.IsFqdn() {
-			var destinationAddresses []netip.Addr
-			destinationAddresses, err = router.Lookup(ctx, metadata.Destination.Fqdn, domainStrategy)
-			if err != nil {
-				return N.ReportHandshakeFailure(conn, err)
-			}
-			outPacketConn, destinationAddress, err = N.ListenSerial(ctx, this, metadata.Destination, destinationAddresses)
-		} else {
-			outPacketConn, err = this.ListenPacket(ctx, metadata.Destination)
-		}
-		if err != nil {
-			return N.ReportHandshakeFailure(conn, err)
-		}
-	}
-	err = N.ReportPacketConnHandshakeSuccess(conn, outPacketConn)
-	if err != nil {
-		outPacketConn.Close()
-		return err
-	}
-	if destinationAddress.IsValid() {
-		if metadata.Destination.IsFqdn() {
-			outPacketConn = bufio.NewNATPacketConn(bufio.NewPacketConn(outPacketConn), M.SocksaddrFrom(destinationAddress, metadata.Destination.Port), metadata.Destination)
-		}
-		if natConn, loaded := common.Cast[bufio.NATPacketConn](conn); loaded {
-			natConn.UpdateDestination(destinationAddress)
-		}
-	}
-	switch metadata.Protocol {
-	case C.ProtocolSTUN:
-		ctx, conn = canceler.NewPacketConn(ctx, conn, C.STUNTimeout)
-	case C.ProtocolQUIC:
-		ctx, conn = canceler.NewPacketConn(ctx, conn, C.QUICTimeout)
-	case C.ProtocolDNS:
-		ctx, conn = canceler.NewPacketConn(ctx, conn, C.DNSTimeout)
-	}
-	return bufio.CopyPacketConn(ctx, conn, bufio.NewPacketConn(outPacketConn))
-}
-
 func CopyEarlyConn(ctx context.Context, conn net.Conn, serverConn net.Conn) error {
 	if cachedReader, isCached := conn.(N.CachedReader); isCached {
 		payload := cachedReader.ReadCached()

common/dialer/default.go

@@ -10,13 +10,17 @@ import (
 	"github.com/sagernet/sing-box/common/conntrack"
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing/common/atomic"
 	"github.com/sagernet/sing/common/control"
 	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 )
 
-var _ WireGuardListener = (*DefaultDialer)(nil)
+var (
+	_ ParallelInterfaceDialer = (*DefaultDialer)(nil)
+	_ WireGuardListener       = (*DefaultDialer)(nil)
+)
 
 type DefaultDialer struct {
 	dialer4              tcpDialer
@@ -27,49 +31,72 @@ type DefaultDialer struct {
 	udpAddr4             string
 	udpAddr6             string
 	isWireGuardListener  bool
+	networkManager       adapter.NetworkManager
+	networkStrategy      C.NetworkStrategy
+	networkFallbackDelay time.Duration
+	networkLastFallback  atomic.TypedValue[time.Time]
 }
 
 func NewDefault(networkManager adapter.NetworkManager, options option.DialerOptions) (*DefaultDialer, error) {
-	var dialer net.Dialer
+	var (
-	var listener net.ListenConfig
+		dialer               net.Dialer
-	if options.BindInterface != "" {
+		listener             net.ListenConfig
-		var interfaceFinder control.InterfaceFinder
+		interfaceFinder      control.InterfaceFinder
+		networkStrategy      C.NetworkStrategy
+		networkFallbackDelay time.Duration
+	)
 	if networkManager != nil {
 		interfaceFinder = networkManager.InterfaceFinder()
 	} else {
 		interfaceFinder = control.NewDefaultInterfaceFinder()
 	}
+	if options.BindInterface != "" {
 		bindFunc := control.BindToInterface(interfaceFinder, options.BindInterface, -1)
 		dialer.Control = control.Append(dialer.Control, bindFunc)
 		listener.Control = control.Append(listener.Control, bindFunc)
-	} else if networkManager != nil && networkManager.AutoDetectInterface() {
-		bindFunc := networkManager.AutoDetectInterfaceFunc()
-		dialer.Control = control.Append(dialer.Control, bindFunc)
-		listener.Control = control.Append(listener.Control, bindFunc)
-	} else if networkManager != nil && networkManager.DefaultInterface() != "" {
-		bindFunc := control.BindToInterface(networkManager.InterfaceFinder(), networkManager.DefaultInterface(), -1)
-		dialer.Control = control.Append(dialer.Control, bindFunc)
-		listener.Control = control.Append(listener.Control, bindFunc)
-	}
-	var autoRedirectOutputMark uint32
-	if networkManager != nil {
-		autoRedirectOutputMark = networkManager.AutoRedirectOutputMark()
-	}
-	if autoRedirectOutputMark > 0 {
-		dialer.Control = control.Append(dialer.Control, control.RoutingMark(autoRedirectOutputMark))
-		listener.Control = control.Append(listener.Control, control.RoutingMark(autoRedirectOutputMark))
 	}
 	if options.RoutingMark > 0 {
 		dialer.Control = control.Append(dialer.Control, control.RoutingMark(options.RoutingMark))
 		listener.Control = control.Append(listener.Control, control.RoutingMark(options.RoutingMark))
-		if autoRedirectOutputMark > 0 {
-			return nil, E.New("`auto_redirect` with `route_[_exclude]_address_set is conflict with `routing_mark`")
 	}
-	} else if networkManager != nil && networkManager.DefaultMark() > 0 {
+	if networkManager != nil {
-		dialer.Control = control.Append(dialer.Control, control.RoutingMark(networkManager.DefaultMark()))
+		autoRedirectOutputMark := networkManager.AutoRedirectOutputMark()
-		listener.Control = control.Append(listener.Control, control.RoutingMark(networkManager.DefaultMark()))
 		if autoRedirectOutputMark > 0 {
-			return nil, E.New("`auto_redirect` with `route_[_exclude]_address_set is conflict with `default_mark`")
+			if options.RoutingMark > 0 {
+				return nil, E.New("`routing_mark` is conflict with `tun.auto_redirect` with `tun.route_[_exclude]_address_set")
+			}
+			dialer.Control = control.Append(dialer.Control, control.RoutingMark(autoRedirectOutputMark))
+			listener.Control = control.Append(listener.Control, control.RoutingMark(autoRedirectOutputMark))
+		}
+	}
+	if C.NetworkStrategy(options.NetworkStrategy) != C.NetworkStrategyDefault {
+		if options.BindInterface != "" || options.Inet4BindAddress != nil || options.Inet6BindAddress != nil {
+			return nil, E.New("`network_strategy` is conflict with `bind_interface`, `inet4_bind_address` and `inet6_bind_address`")
+		}
+		networkStrategy = C.NetworkStrategy(options.NetworkStrategy)
+		networkFallbackDelay = time.Duration(options.NetworkFallbackDelay)
+		if networkManager == nil || !networkManager.AutoDetectInterface() {
+			return nil, E.New("`route.auto_detect_interface` is require by `network_strategy`")
+		}
+	}
+	if networkManager != nil && options.BindInterface == "" && options.Inet4BindAddress == nil && options.Inet6BindAddress == nil {
+		defaultOptions := networkManager.DefaultOptions()
+		if defaultOptions.DefaultInterface != "" {
+			bindFunc := control.BindToInterface(networkManager.InterfaceFinder(), defaultOptions.DefaultInterface, -1)
+			dialer.Control = control.Append(dialer.Control, bindFunc)
+			listener.Control = control.Append(listener.Control, bindFunc)
+		} else if networkManager.AutoDetectInterface() {
+			if defaultOptions.DefaultNetworkStrategy != C.NetworkStrategyDefault && C.NetworkStrategy(options.NetworkStrategy) == C.NetworkStrategyDefault {
+				networkStrategy = defaultOptions.DefaultNetworkStrategy
+				networkFallbackDelay = defaultOptions.DefaultFallbackDelay
+				bindFunc := networkManager.ProtectFunc()
+				dialer.Control = control.Append(dialer.Control, bindFunc)
+				listener.Control = control.Append(listener.Control, bindFunc)
+			} else {
+				bindFunc := networkManager.AutoDetectInterfaceFunc()
+				dialer.Control = control.Append(dialer.Control, bindFunc)
+				listener.Control = control.Append(listener.Control, bindFunc)
+			}
 		}
 	}
 	if options.ReuseAddr {
@@ -130,6 +157,9 @@ func NewDefault(networkManager adapter.NetworkManager, options option.DialerOpti
 			listener.Control = control.Append(listener.Control, controlFn)
 		}
 	}
+	if networkStrategy != C.NetworkStrategyDefault && options.TCPFastOpen {
+		return nil, E.New("`tcp_fast_open` is conflict with `network_strategy` or `route.default_network_strategy`")
+	}
 	tcpDialer4, err := newTCPDialer(dialer4, options.TCPFastOpen)
 	if err != nil {
 		return nil, err
@@ -139,14 +169,17 @@ func NewDefault(networkManager adapter.NetworkManager, options option.DialerOpti
 		return nil, err
 	}
 	return &DefaultDialer{
-		tcpDialer4,
+		dialer4:              tcpDialer4,
-		tcpDialer6,
+		dialer6:              tcpDialer6,
-		udpDialer4,
+		udpDialer4:           udpDialer4,
-		udpDialer6,
+		udpDialer6:           udpDialer6,
-		listener,
+		udpListener:          listener,
-		udpAddr4,
+		udpAddr4:             udpAddr4,
-		udpAddr6,
+		udpAddr6:             udpAddr6,
-		options.IsWireGuardListener,
+		isWireGuardListener:  options.IsWireGuardListener,
+		networkManager:       networkManager,
+		networkStrategy:      networkStrategy,
+		networkFallbackDelay: networkFallbackDelay,
 	}, nil
 }
 
@@ -154,6 +187,7 @@ func (d *DefaultDialer) DialContext(ctx context.Context, network string, address
 	if !address.IsValid() {
 		return nil, E.New("invalid address")
 	}
+	if d.networkStrategy == C.NetworkStrategyDefault {
 		switch N.NetworkName(network) {
 		case N.NetworkUDP:
 			if !address.IsIPv6() {
@@ -167,9 +201,46 @@ func (d *DefaultDialer) DialContext(ctx context.Context, network string, address
 		} else {
 			return trackConn(DialSlowContext(&d.dialer6, ctx, network, address))
 		}
+	} else {
+		return d.DialParallelInterface(ctx, network, address, d.networkStrategy, d.networkFallbackDelay)
+	}
+}
+
+func (d *DefaultDialer) DialParallelInterface(ctx context.Context, network string, address M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error) {
+	if strategy == C.NetworkStrategyDefault {
+		return d.DialContext(ctx, network, address)
+	}
+	if !d.networkManager.AutoDetectInterface() {
+		return nil, E.New("`route.auto_detect_interface` is require by `network_strategy`")
+	}
+	var dialer net.Dialer
+	if N.NetworkName(network) == N.NetworkTCP {
+		dialer = dialerFromTCPDialer(d.dialer4)
+	} else {
+		dialer = d.udpDialer4
+	}
+	fastFallback := time.Now().Sub(d.networkLastFallback.Load()) < C.TCPTimeout
+	var (
+		conn      net.Conn
+		isPrimary bool
+		err       error
+	)
+	if !fastFallback {
+		conn, isPrimary, err = d.dialParallelInterface(ctx, dialer, network, address.String(), strategy, fallbackDelay)
+	} else {
+		conn, isPrimary, err = d.dialParallelInterfaceFastFallback(ctx, dialer, network, address.String(), strategy, fallbackDelay, d.networkLastFallback.Store)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if !fastFallback && !isPrimary {
+		d.networkLastFallback.Store(time.Now())
+	}
+	return trackConn(conn, nil)
 }
 
 func (d *DefaultDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+	if d.networkStrategy == C.NetworkStrategyDefault {
 		if destination.IsIPv6() {
 			return trackPacketConn(d.udpListener.ListenPacket(ctx, N.NetworkUDP, d.udpAddr6))
 		} else if destination.IsIPv4() && !destination.Addr.IsUnspecified() {
@@ -177,10 +248,27 @@ func (d *DefaultDialer) ListenPacket(ctx context.Context, destination M.Socksadd
 		} else {
 			return trackPacketConn(d.udpListener.ListenPacket(ctx, N.NetworkUDP, d.udpAddr4))
 		}
+	} else {
+		return d.ListenSerialInterfacePacket(ctx, destination, d.networkStrategy, d.networkFallbackDelay)
+	}
+}
+
+func (d *DefaultDialer) ListenSerialInterfacePacket(ctx context.Context, destination M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, error) {
+	if strategy == C.NetworkStrategyDefault {
+		return d.ListenPacket(ctx, destination)
+	}
+	if !d.networkManager.AutoDetectInterface() {
+		return nil, E.New("`route.auto_detect_interface` is require by `network_strategy`")
+	}
+	network := N.NetworkUDP
+	if destination.IsIPv4() && !destination.Addr.IsUnspecified() {
+		network += "4"
+	}
+	return trackPacketConn(d.listenSerialInterfacePacket(ctx, d.udpListener, network, "", strategy, fallbackDelay))
 }
 
 func (d *DefaultDialer) ListenPacketCompat(network, address string) (net.PacketConn, error) {
-	return trackPacketConn(d.udpListener.ListenPacket(context.Background(), network, address))
+	return trackPacketConn(d.listenSerialInterfacePacket(context.Background(), d.udpListener, network, address, d.networkStrategy, d.networkFallbackDelay))
 }
 
 func trackConn(conn net.Conn, err error) (net.Conn, error) {

common/dialer/default_go1.20.go

@@ -13,3 +13,7 @@ type tcpDialer = tfo.Dialer
 func newTCPDialer(dialer net.Dialer, tfoEnabled bool) (tcpDialer, error) {
 	return tfo.Dialer{Dialer: dialer, DisableTFO: !tfoEnabled}, nil
 }
+
+func dialerFromTCPDialer(dialer tcpDialer) net.Dialer {
+	return dialer.Dialer
+}

common/dialer/default_nongo1.20.go

@@ -16,3 +16,7 @@ func newTCPDialer(dialer net.Dialer, tfoEnabled bool) (tcpDialer, error) {
 	}
 	return dialer, nil
 }
+
+func dialerFromTCPDialer(dialer tcpDialer) net.Dialer {
+	return dialer
+}

common/dialer/default_parallel_interface.go

@@ -0,0 +1,241 @@
+package dialer
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing/common/control"
+	E "github.com/sagernet/sing/common/exceptions"
+	F "github.com/sagernet/sing/common/format"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func (d *DefaultDialer) dialParallelInterface(ctx context.Context, dialer net.Dialer, network string, addr string, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, bool, error) {
+	primaryInterfaces, fallbackInterfaces := selectInterfaces(d.networkManager, strategy)
+	if len(primaryInterfaces)+len(fallbackInterfaces) == 0 {
+		return nil, false, E.New("no available network interface")
+	}
+	if fallbackDelay == 0 {
+		fallbackDelay = N.DefaultFallbackDelay
+	}
+	returned := make(chan struct{})
+	defer close(returned)
+	type dialResult struct {
+		net.Conn
+		error
+		primary bool
+	}
+	results := make(chan dialResult) // unbuffered
+	startRacer := func(ctx context.Context, primary bool, iif adapter.NetworkInterface) {
+		perNetDialer := dialer
+		perNetDialer.Control = control.Append(perNetDialer.Control, control.BindToInterface(nil, iif.Name, iif.Index))
+		conn, err := perNetDialer.DialContext(ctx, network, addr)
+		if err != nil {
+			select {
+			case results <- dialResult{error: E.Cause(err, "dial ", iif.Name, " (", iif.Name, ")"), primary: primary}:
+			case <-returned:
+			}
+		} else {
+			select {
+			case results <- dialResult{Conn: conn}:
+			case <-returned:
+				conn.Close()
+			}
+		}
+	}
+	primaryCtx, primaryCancel := context.WithCancel(ctx)
+	defer primaryCancel()
+	for _, iif := range primaryInterfaces {
+		go startRacer(primaryCtx, true, iif)
+	}
+	var (
+		fallbackTimer *time.Timer
+		fallbackChan  <-chan time.Time
+	)
+	if len(fallbackInterfaces) > 0 {
+		fallbackTimer = time.NewTimer(fallbackDelay)
+		defer fallbackTimer.Stop()
+		fallbackChan = fallbackTimer.C
+	}
+	var errors []error
+	for {
+		select {
+		case <-fallbackChan:
+			fallbackCtx, fallbackCancel := context.WithCancel(ctx)
+			defer fallbackCancel()
+			for _, iif := range fallbackInterfaces {
+				go startRacer(fallbackCtx, false, iif)
+			}
+		case res := <-results:
+			if res.error == nil {
+				return res.Conn, res.primary, nil
+			}
+			errors = append(errors, res.error)
+			if len(errors) == len(primaryInterfaces)+len(fallbackInterfaces) {
+				return nil, false, E.Errors(errors...)
+			}
+			if res.primary && fallbackTimer != nil && fallbackTimer.Stop() {
+				fallbackTimer.Reset(0)
+			}
+		}
+	}
+}
+
+func (d *DefaultDialer) dialParallelInterfaceFastFallback(ctx context.Context, dialer net.Dialer, network string, addr string, strategy C.NetworkStrategy, fallbackDelay time.Duration, resetFastFallback func(time.Time)) (net.Conn, bool, error) {
+	primaryInterfaces, fallbackInterfaces := selectInterfaces(d.networkManager, strategy)
+	if len(primaryInterfaces)+len(fallbackInterfaces) == 0 {
+		return nil, false, E.New("no available network interface")
+	}
+	if fallbackDelay == 0 {
+		fallbackDelay = N.DefaultFallbackDelay
+	}
+	returned := make(chan struct{})
+	defer close(returned)
+	type dialResult struct {
+		net.Conn
+		error
+		primary bool
+	}
+	startAt := time.Now()
+	results := make(chan dialResult) // unbuffered
+	startRacer := func(ctx context.Context, primary bool, iif adapter.NetworkInterface) {
+		perNetDialer := dialer
+		perNetDialer.Control = control.Append(perNetDialer.Control, control.BindToInterface(nil, iif.Name, iif.Index))
+		conn, err := perNetDialer.DialContext(ctx, network, addr)
+		if err != nil {
+			select {
+			case results <- dialResult{error: E.Cause(err, "dial ", iif.Name, " (", iif.Name, ")"), primary: primary}:
+			case <-returned:
+			}
+		} else {
+			select {
+			case results <- dialResult{Conn: conn}:
+			case <-returned:
+				if primary && time.Since(startAt) <= fallbackDelay {
+					resetFastFallback(time.Time{})
+				}
+				conn.Close()
+			}
+		}
+	}
+	for _, iif := range primaryInterfaces {
+		go startRacer(ctx, true, iif)
+	}
+	fallbackCtx, fallbackCancel := context.WithCancel(ctx)
+	defer fallbackCancel()
+	for _, iif := range fallbackInterfaces {
+		go startRacer(fallbackCtx, false, iif)
+	}
+	var errors []error
+	for {
+		select {
+		case res := <-results:
+			if res.error == nil {
+				return res.Conn, res.primary, nil
+			}
+			errors = append(errors, res.error)
+			if len(errors) == len(primaryInterfaces)+len(fallbackInterfaces) {
+				return nil, false, E.Errors(errors...)
+			}
+		}
+	}
+}
+
+func (d *DefaultDialer) listenSerialInterfacePacket(ctx context.Context, listener net.ListenConfig, network string, addr string, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, error) {
+	primaryInterfaces, fallbackInterfaces := selectInterfaces(d.networkManager, strategy)
+	if len(primaryInterfaces)+len(fallbackInterfaces) == 0 {
+		return nil, E.New("no available network interface")
+	}
+	if fallbackDelay == 0 {
+		fallbackDelay = N.DefaultFallbackDelay
+	}
+	var errors []error
+	for _, primaryInterface := range primaryInterfaces {
+		perNetListener := listener
+		perNetListener.Control = control.Append(perNetListener.Control, control.BindToInterface(nil, primaryInterface.Name, primaryInterface.Index))
+		conn, err := perNetListener.ListenPacket(ctx, network, addr)
+		if err == nil {
+			return conn, nil
+		}
+		errors = append(errors, E.Cause(err, "listen ", primaryInterface.Name, " (", primaryInterface.Name, ")"))
+	}
+	for _, fallbackInterface := range fallbackInterfaces {
+		perNetListener := listener
+		perNetListener.Control = control.Append(perNetListener.Control, control.BindToInterface(nil, fallbackInterface.Name, fallbackInterface.Index))
+		conn, err := perNetListener.ListenPacket(ctx, network, addr)
+		if err == nil {
+			return conn, nil
+		}
+		errors = append(errors, E.Cause(err, "listen ", fallbackInterface.Name, " (", fallbackInterface.Name, ")"))
+	}
+	return nil, E.Errors(errors...)
+}
+
+func selectInterfaces(networkManager adapter.NetworkManager, strategy C.NetworkStrategy) (primaryInterfaces []adapter.NetworkInterface, fallbackInterfaces []adapter.NetworkInterface) {
+	interfaces := networkManager.NetworkInterfaces()
+	switch strategy {
+	case C.NetworkStrategyFallback:
+		defaultIf := networkManager.InterfaceMonitor().DefaultInterface()
+		if defaultIf != nil {
+			for _, iif := range interfaces {
+				if iif.Index == defaultIf.Index {
+					primaryInterfaces = append(primaryInterfaces, iif)
+				} else {
+					fallbackInterfaces = append(fallbackInterfaces, iif)
+				}
+			}
+		} else {
+			primaryInterfaces = interfaces
+		}
+	case C.NetworkStrategyHybrid:
+		primaryInterfaces = interfaces
+	case C.NetworkStrategyWIFI:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeWIFI {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			} else {
+				fallbackInterfaces = append(fallbackInterfaces, iif)
+			}
+		}
+	case C.NetworkStrategyCellular:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeCellular {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			} else {
+				fallbackInterfaces = append(fallbackInterfaces, iif)
+			}
+		}
+	case C.NetworkStrategyEthernet:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeEthernet {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			} else {
+				fallbackInterfaces = append(fallbackInterfaces, iif)
+			}
+		}
+	case C.NetworkStrategyWIFIOnly:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeWIFI {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			}
+		}
+	case C.NetworkStrategyCellularOnly:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeCellular {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			}
+		}
+	case C.NetworkStrategyEthernetOnly:
+		for _, iif := range interfaces {
+			if iif.Type == C.InterfaceTypeEthernet {
+				primaryInterfaces = append(primaryInterfaces, iif)
+			}
+		}
+	default:
+		panic(F.ToString("unknown network strategy: ", strategy))
+	}
+	return primaryInterfaces, fallbackInterfaces
+}

common/dialer/default_parallel_network.go

@@ -0,0 +1,122 @@
+package dialer
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"time"
+
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing/common"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func DialSerialNetwork(ctx context.Context, dialer ParallelInterfaceDialer, network string, destination M.Socksaddr, destinationAddresses []netip.Addr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error) {
+	if parallelDialer, isParallel := dialer.(ParallelNetworkDialer); isParallel {
+		return parallelDialer.DialParallelNetwork(ctx, network, destination, destinationAddresses, strategy, fallbackDelay)
+	}
+	var errors []error
+	for _, address := range destinationAddresses {
+		conn, err := dialer.DialParallelInterface(ctx, network, M.SocksaddrFrom(address, destination.Port), strategy, fallbackDelay)
+		if err == nil {
+			return conn, nil
+		}
+		errors = append(errors, err)
+	}
+	return nil, E.Errors(errors...)
+}
+
+func DialParallelNetwork(ctx context.Context, dialer ParallelInterfaceDialer, network string, destination M.Socksaddr, destinationAddresses []netip.Addr, preferIPv6 bool, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error) {
+	if fallbackDelay == 0 {
+		fallbackDelay = N.DefaultFallbackDelay
+	}
+
+	returned := make(chan struct{})
+	defer close(returned)
+
+	addresses4 := common.Filter(destinationAddresses, func(address netip.Addr) bool {
+		return address.Is4() || address.Is4In6()
+	})
+	addresses6 := common.Filter(destinationAddresses, func(address netip.Addr) bool {
+		return address.Is6() && !address.Is4In6()
+	})
+	if len(addresses4) == 0 || len(addresses6) == 0 {
+		return DialSerialNetwork(ctx, dialer, network, destination, destinationAddresses, strategy, fallbackDelay)
+	}
+	var primaries, fallbacks []netip.Addr
+	if preferIPv6 {
+		primaries = addresses6
+		fallbacks = addresses4
+	} else {
+		primaries = addresses4
+		fallbacks = addresses6
+	}
+	type dialResult struct {
+		net.Conn
+		error
+		primary bool
+		done    bool
+	}
+	results := make(chan dialResult) // unbuffered
+	startRacer := func(ctx context.Context, primary bool) {
+		ras := primaries
+		if !primary {
+			ras = fallbacks
+		}
+		c, err := DialSerialNetwork(ctx, dialer, network, destination, ras, strategy, fallbackDelay)
+		select {
+		case results <- dialResult{Conn: c, error: err, primary: primary, done: true}:
+		case <-returned:
+			if c != nil {
+				c.Close()
+			}
+		}
+	}
+	var primary, fallback dialResult
+	primaryCtx, primaryCancel := context.WithCancel(ctx)
+	defer primaryCancel()
+	go startRacer(primaryCtx, true)
+	fallbackTimer := time.NewTimer(fallbackDelay)
+	defer fallbackTimer.Stop()
+	for {
+		select {
+		case <-fallbackTimer.C:
+			fallbackCtx, fallbackCancel := context.WithCancel(ctx)
+			defer fallbackCancel()
+			go startRacer(fallbackCtx, false)
+
+		case res := <-results:
+			if res.error == nil {
+				return res.Conn, nil
+			}
+			if res.primary {
+				primary = res
+			} else {
+				fallback = res
+			}
+			if primary.done && fallback.done {
+				return nil, primary.error
+			}
+			if res.primary && fallbackTimer.Stop() {
+				fallbackTimer.Reset(0)
+			}
+		}
+	}
+}
+
+func ListenSerialNetworkPacket(ctx context.Context, dialer ParallelInterfaceDialer, destination M.Socksaddr, destinationAddresses []netip.Addr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, netip.Addr, error) {
+	if parallelDialer, isParallel := dialer.(ParallelNetworkDialer); isParallel {
+		return parallelDialer.ListenSerialNetworkPacket(ctx, destination, destinationAddresses, strategy, fallbackDelay)
+	}
+	var errors []error
+	for _, address := range destinationAddresses {
+		conn, err := dialer.ListenSerialInterfacePacket(ctx, M.SocksaddrFrom(address, destination.Port), strategy, fallbackDelay)
+		if err == nil {
+			return conn, address, nil
+		}
+		errors = append(errors, err)
+	}
+	return nil, netip.Addr{}, E.Errors(errors...)
+}

common/dialer/dialer.go

@@ -2,12 +2,16 @@ package dialer
 
 import (
 	"context"
+	"net"
+	"net/netip"
 	"time"
 
 	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/option"
 	"github.com/sagernet/sing-dns"
 	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/service"
 )
@@ -49,3 +53,35 @@ func New(ctx context.Context, options option.DialerOptions) (N.Dialer, error) {
 	}
 	return dialer, nil
 }
+
+func NewDirect(ctx context.Context, options option.DialerOptions) (ParallelInterfaceDialer, error) {
+	if options.Detour != "" {
+		return nil, E.New("`detour` is not supported in direct context")
+	}
+	networkManager := service.FromContext[adapter.NetworkManager](ctx)
+	if options.IsWireGuardListener {
+		return NewDefault(networkManager, options)
+	}
+	dialer, err := NewDefault(networkManager, options)
+	if err != nil {
+		return nil, err
+	}
+	return NewResolveParallelInterfaceDialer(
+		service.FromContext[adapter.Router](ctx),
+		dialer,
+		true,
+		dns.DomainStrategy(options.DomainStrategy),
+		time.Duration(options.FallbackDelay),
+	), nil
+}
+
+type ParallelInterfaceDialer interface {
+	N.Dialer
+	DialParallelInterface(ctx context.Context, network string, destination M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error)
+	ListenSerialInterfacePacket(ctx context.Context, destination M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, error)
+}
+
+type ParallelNetworkDialer interface {
+	DialParallelNetwork(ctx context.Context, network string, destination M.Socksaddr, destinationAddresses []netip.Addr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error)
+	ListenSerialNetworkPacket(ctx context.Context, destination M.Socksaddr, destinationAddresses []netip.Addr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, netip.Addr, error)
+}

common/dialer/resolve.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-dns"
 	"github.com/sagernet/sing/common/bufio"
@@ -14,7 +15,12 @@ import (
 	N "github.com/sagernet/sing/common/network"
 )
 
-type ResolveDialer struct {
+var (
+	_ N.Dialer                = (*resolveDialer)(nil)
+	_ ParallelInterfaceDialer = (*resolveParallelNetworkDialer)(nil)
+)
+
+type resolveDialer struct {
 	dialer        N.Dialer
 	parallel      bool
 	router        adapter.Router
@@ -22,8 +28,8 @@ type ResolveDialer struct {
 	fallbackDelay time.Duration
 }
 
-func NewResolveDialer(router adapter.Router, dialer N.Dialer, parallel bool, strategy dns.DomainStrategy, fallbackDelay time.Duration) *ResolveDialer {
+func NewResolveDialer(router adapter.Router, dialer N.Dialer, parallel bool, strategy dns.DomainStrategy, fallbackDelay time.Duration) N.Dialer {
-	return &ResolveDialer{
+	return &resolveDialer{
 		dialer,
 		parallel,
 		router,
@@ -32,7 +38,25 @@ func NewResolveDialer(router adapter.Router, dialer N.Dialer, parallel bool, str
 	}
 }
 
-func (d *ResolveDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
+type resolveParallelNetworkDialer struct {
+	resolveDialer
+	dialer ParallelInterfaceDialer
+}
+
+func NewResolveParallelInterfaceDialer(router adapter.Router, dialer ParallelInterfaceDialer, parallel bool, strategy dns.DomainStrategy, fallbackDelay time.Duration) ParallelInterfaceDialer {
+	return &resolveParallelNetworkDialer{
+		resolveDialer{
+			dialer,
+			parallel,
+			router,
+			strategy,
+			fallbackDelay,
+		},
+		dialer,
+	}
+}
+
+func (d *resolveDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
 	if !destination.IsFqdn() {
 		return d.dialer.DialContext(ctx, network, destination)
 	}
@@ -57,7 +81,7 @@ func (d *ResolveDialer) DialContext(ctx context.Context, network string, destina
 	}
 }
 
-func (d *ResolveDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+func (d *resolveDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
 	if !destination.IsFqdn() {
 		return d.dialer.ListenPacket(ctx, destination)
 	}
@@ -82,6 +106,59 @@ func (d *ResolveDialer) ListenPacket(ctx context.Context, destination M.Socksadd
 	return bufio.NewNATPacketConn(bufio.NewPacketConn(conn), M.SocksaddrFrom(destinationAddress, destination.Port), destination), nil
 }
 
-func (d *ResolveDialer) Upstream() any {
+func (d *resolveParallelNetworkDialer) DialParallelInterface(ctx context.Context, network string, destination M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error) {
+	if !destination.IsFqdn() {
+		return d.dialer.DialContext(ctx, network, destination)
+	}
+	ctx, metadata := adapter.ExtendContext(ctx)
+	ctx = log.ContextWithOverrideLevel(ctx, log.LevelDebug)
+	metadata.Destination = destination
+	metadata.Domain = ""
+	var addresses []netip.Addr
+	var err error
+	if d.strategy == dns.DomainStrategyAsIS {
+		addresses, err = d.router.LookupDefault(ctx, destination.Fqdn)
+	} else {
+		addresses, err = d.router.Lookup(ctx, destination.Fqdn, d.strategy)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if fallbackDelay == 0 {
+		fallbackDelay = d.fallbackDelay
+	}
+	if d.parallel {
+		return DialParallelNetwork(ctx, d.dialer, network, destination, addresses, d.strategy == dns.DomainStrategyPreferIPv6, strategy, fallbackDelay)
+	} else {
+		return DialSerialNetwork(ctx, d.dialer, network, destination, addresses, strategy, fallbackDelay)
+	}
+}
+
+func (d *resolveParallelNetworkDialer) ListenSerialInterfacePacket(ctx context.Context, destination M.Socksaddr, strategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, error) {
+	if !destination.IsFqdn() {
+		return d.dialer.ListenPacket(ctx, destination)
+	}
+	ctx, metadata := adapter.ExtendContext(ctx)
+	ctx = log.ContextWithOverrideLevel(ctx, log.LevelDebug)
+	metadata.Destination = destination
+	metadata.Domain = ""
+	var addresses []netip.Addr
+	var err error
+	if d.strategy == dns.DomainStrategyAsIS {
+		addresses, err = d.router.LookupDefault(ctx, destination.Fqdn)
+	} else {
+		addresses, err = d.router.Lookup(ctx, destination.Fqdn, d.strategy)
+	}
+	if err != nil {
+		return nil, err
+	}
+	conn, destinationAddress, err := ListenSerialNetworkPacket(ctx, d.dialer, destination, addresses, strategy, fallbackDelay)
+	if err != nil {
+		return nil, err
+	}
+	return bufio.NewNATPacketConn(bufio.NewPacketConn(conn), M.SocksaddrFrom(destinationAddress, destination.Port), destination), nil
+}
+
+func (d *resolveDialer) Upstream() any {
 	return d.dialer
 }

common/settings/proxy_darwin.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common/control"
 	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/sing/common/shell"
@@ -33,7 +34,7 @@ func NewSystemProxy(ctx context.Context, serverAddr M.Socksaddr, supportSOCKS bo
 		serverAddr:   serverAddr,
 		supportSOCKS: supportSOCKS,
 	}
-	proxy.element = interfaceMonitor.RegisterCallback(proxy.update)
+	proxy.element = interfaceMonitor.RegisterCallback(proxy.routeUpdate)
 	return proxy, nil
 }
 
@@ -65,11 +66,8 @@ func (p *DarwinSystemProxy) Disable() error {
 	return err
 }
 
-func (p *DarwinSystemProxy) update(event int) {
+func (p *DarwinSystemProxy) routeUpdate(defaultInterface *control.Interface, flags int) {
-	if event&tun.EventInterfaceUpdate == 0 {
+	if !p.isEnabled || defaultInterface == nil {
-		return
-	}
-	if !p.isEnabled {
 		return
 	}
 	_ = p.update0()

constant/network.go

@@ -1,8 +1,50 @@
 package constant
 
+import (
+	"github.com/sagernet/sing/common"
+	F "github.com/sagernet/sing/common/format"
+)
+
 const (
 	InterfaceTypeWIFI     = "wifi"
 	InterfaceTypeCellular = "cellular"
 	InterfaceTypeEthernet = "ethernet"
 	InterfaceTypeOther    = "other"
 )
+
+type NetworkStrategy int
+
+const (
+	NetworkStrategyDefault NetworkStrategy = iota
+	NetworkStrategyFallback
+	NetworkStrategyHybrid
+	NetworkStrategyWIFI
+	NetworkStrategyCellular
+	NetworkStrategyEthernet
+	NetworkStrategyWIFIOnly
+	NetworkStrategyCellularOnly
+	NetworkStrategyEthernetOnly
+)
+
+var (
+	NetworkStrategyToString = map[NetworkStrategy]string{
+		NetworkStrategyDefault:      "default",
+		NetworkStrategyFallback:     "fallback",
+		NetworkStrategyHybrid:       "hybrid",
+		NetworkStrategyWIFI:         "wifi",
+		NetworkStrategyCellular:     "cellular",
+		NetworkStrategyEthernet:     "ethernet",
+		NetworkStrategyWIFIOnly:     "wifi_only",
+		NetworkStrategyCellularOnly: "cellular_only",
+		NetworkStrategyEthernetOnly: "ethernet_only",
+	}
+	StringToNetworkStrategy = common.ReverseMap(NetworkStrategyToString)
+)
+
+func (s NetworkStrategy) String() string {
+	name, loaded := NetworkStrategyToString[s]
+	if !loaded {
+		return F.ToString(int(s))
+	}
+	return name
+}

experimental/libbox/monitor.go

@@ -67,7 +67,7 @@ func (m *platformDefaultInterfaceMonitor) UpdateDefaultInterface(interfaceName s
 		callbacks := m.callbacks.Array()
 		m.defaultInterfaceAccess.Unlock()
 		for _, callback := range callbacks {
-			callback(tun.EventInterfaceUpdate)
+			callback(nil, 0)
 		}
 		return
 	}
@@ -86,6 +86,6 @@ func (m *platformDefaultInterfaceMonitor) UpdateDefaultInterface(interfaceName s
 	callbacks := m.callbacks.Array()
 	m.defaultInterfaceAccess.Unlock()
 	for _, callback := range callbacks {
-		callback(tun.EventInterfaceUpdate)
+		callback(newInterface, 0)
 	}
 }

option/outbound.go

@@ -78,7 +78,9 @@ type DialerOptions struct {
 	UDPFragment          *bool              `json:"udp_fragment,omitempty"`
 	UDPFragmentDefault   bool               `json:"-"`
 	DomainStrategy       DomainStrategy     `json:"domain_strategy,omitempty"`
+	NetworkStrategy      NetworkStrategy    `json:"network_strategy,omitempty"`
 	FallbackDelay        badoption.Duration `json:"fallback_delay,omitempty"`
+	NetworkFallbackDelay badoption.Duration `json:"network_fallback_delay,omitempty"`
 	IsWireGuardListener  bool               `json:"-"`
 }
 

option/route.go

@@ -1,5 +1,7 @@
 package option
 
+import "github.com/sagernet/sing/common/json/badoption"
+
 type RouteOptions struct {
 	GeoIP                  *GeoIPOptions      `json:"geoip,omitempty"`
 	Geosite                *GeositeOptions    `json:"geosite,omitempty"`
@@ -11,6 +13,8 @@ type RouteOptions struct {
 	OverrideAndroidVPN     bool               `json:"override_android_vpn,omitempty"`
 	DefaultInterface       string             `json:"default_interface,omitempty"`
 	DefaultMark            uint32             `json:"default_mark,omitempty"`
+	DefaultNetworkStrategy NetworkStrategy    `json:"default_network_strategy,omitempty"`
+	DefaultFallbackDelay   badoption.Duration `json:"default_fallback_delay,omitempty"`
 }
 
 type GeoIPOptions struct {

option/rule_action.go

@@ -138,11 +138,15 @@ func (r *DNSRuleAction) UnmarshalJSONContext(ctx context.Context, data []byte) e
 
 type RouteActionOptions struct {
 	Outbound                  string          `json:"outbound,omitempty"`
+	NetworkStrategy           NetworkStrategy `json:"network_strategy,omitempty"`
+	FallbackDelay             uint32          `json:"fallback_delay,omitempty"`
 	UDPDisableDomainUnmapping bool            `json:"udp_disable_domain_unmapping,omitempty"`
 	UDPConnect                bool            `json:"udp_connect,omitempty"`
 }
 
 type _RouteOptionsActionOptions struct {
+	NetworkStrategy           NetworkStrategy `json:"network_strategy,omitempty"`
+	FallbackDelay             uint32          `json:"fallback_delay,omitempty"`
 	UDPDisableDomainUnmapping bool            `json:"udp_disable_domain_unmapping,omitempty"`
 	UDPConnect                bool            `json:"udp_connect,omitempty"`
 }

option/types.go

@@ -3,6 +3,7 @@ package option
 import (
 	"strings"
 
+	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-dns"
 	E "github.com/sagernet/sing/common/exceptions"
 	F "github.com/sagernet/sing/common/format"
@@ -150,3 +151,23 @@ func DNSQueryTypeToString(queryType uint16) string {
 	}
 	return F.ToString(queryType)
 }
+
+type NetworkStrategy C.NetworkStrategy
+
+func (n NetworkStrategy) MarshalJSON() ([]byte, error) {
+	return json.Marshal(C.NetworkStrategy(n).String())
+}
+
+func (n *NetworkStrategy) UnmarshalJSON(content []byte) error {
+	var value string
+	err := json.Unmarshal(content, &value)
+	if err != nil {
+		return err
+	}
+	strategy, loaded := C.StringToNetworkStrategy[value]
+	if !loaded {
+		return E.New("unknown network strategy: ", value)
+	}
+	*n = NetworkStrategy(strategy)
+	return nil
+}

protocol/direct/outbound.go

@@ -13,6 +13,7 @@ import (
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
 	dns "github.com/sagernet/sing-dns"
+	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/bufio"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/logger"
@@ -24,14 +25,19 @@ func RegisterOutbound(registry *outbound.Registry) {
 	outbound.Register[option.DirectOutboundOptions](registry, C.TypeDirect, NewOutbound)
 }
 
-var _ N.ParallelDialer = (*Outbound)(nil)
+var (
+	_ N.ParallelDialer             = (*Outbound)(nil)
+	_ dialer.ParallelNetworkDialer = (*Outbound)(nil)
+)
 
 type Outbound struct {
 	outbound.Adapter
 	logger               logger.ContextLogger
-	dialer              N.Dialer
+	dialer               dialer.ParallelInterfaceDialer
 	domainStrategy       dns.DomainStrategy
 	fallbackDelay        time.Duration
+	networkStrategy      C.NetworkStrategy
+	networkFallbackDelay time.Duration
 	overrideOption       int
 	overrideDestination  M.Socksaddr
 	// loopBack *loopBackDetector
@@ -39,7 +45,7 @@ type Outbound struct {
 
 func NewOutbound(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.DirectOutboundOptions) (adapter.Outbound, error) {
 	options.UDPFragmentDefault = true
-	outboundDialer, err := dialer.New(ctx, options.DialerOptions)
+	outboundDialer, err := dialer.NewDirect(ctx, options.DialerOptions)
 	if err != nil {
 		return nil, err
 	}
@@ -48,6 +54,8 @@ func NewOutbound(ctx context.Context, router adapter.Router, logger log.ContextL
 		logger:               logger,
 		domainStrategy:       dns.DomainStrategy(options.DomainStrategy),
 		fallbackDelay:        time.Duration(options.FallbackDelay),
+		networkStrategy:      C.NetworkStrategy(options.NetworkStrategy),
+		networkFallbackDelay: time.Duration(options.NetworkFallbackDelay),
 		dialer:               outboundDialer,
 		// loopBack:       newLoopBackDetector(router),
 	}
@@ -96,33 +104,6 @@ func (h *Outbound) DialContext(ctx context.Context, network string, destination
 	return h.dialer.DialContext(ctx, network, destination)
 }
 
-func (h *Outbound) DialParallel(ctx context.Context, network string, destination M.Socksaddr, destinationAddresses []netip.Addr) (net.Conn, error) {
-	ctx, metadata := adapter.ExtendContext(ctx)
-	metadata.Outbound = h.Tag()
-	metadata.Destination = destination
-	switch h.overrideOption {
-	case 1, 2:
-		// override address
-		return h.DialContext(ctx, network, destination)
-	case 3:
-		destination.Port = h.overrideDestination.Port
-	}
-	network = N.NetworkName(network)
-	switch network {
-	case N.NetworkTCP:
-		h.logger.InfoContext(ctx, "outbound connection to ", destination)
-	case N.NetworkUDP:
-		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
-	}
-	var domainStrategy dns.DomainStrategy
-	if h.domainStrategy != dns.DomainStrategyAsIS {
-		domainStrategy = h.domainStrategy
-	} else {
-		domainStrategy = dns.DomainStrategy(metadata.InboundOptions.DomainStrategy)
-	}
-	return N.DialParallel(ctx, h.dialer, network, destination, destinationAddresses, domainStrategy == dns.DomainStrategyPreferIPv6, h.fallbackDelay)
-}
-
 func (h *Outbound) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
 	ctx, metadata := adapter.ExtendContext(ctx)
 	metadata.Outbound = h.Tag()
@@ -154,6 +135,110 @@ func (h *Outbound) ListenPacket(ctx context.Context, destination M.Socksaddr) (n
 	return conn, nil
 }
 
+func (h *Outbound) DialParallel(ctx context.Context, network string, destination M.Socksaddr, destinationAddresses []netip.Addr) (net.Conn, error) {
+	ctx, metadata := adapter.ExtendContext(ctx)
+	metadata.Outbound = h.Tag()
+	metadata.Destination = destination
+	switch h.overrideOption {
+	case 1, 2:
+		// override address
+		return h.DialContext(ctx, network, destination)
+	case 3:
+		destination.Port = h.overrideDestination.Port
+	}
+	network = N.NetworkName(network)
+	switch network {
+	case N.NetworkTCP:
+		h.logger.InfoContext(ctx, "outbound connection to ", destination)
+	case N.NetworkUDP:
+		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
+	}
+	var domainStrategy dns.DomainStrategy
+	if h.domainStrategy != dns.DomainStrategyAsIS {
+		domainStrategy = h.domainStrategy
+	} else {
+		domainStrategy = dns.DomainStrategy(metadata.InboundOptions.DomainStrategy)
+	}
+	switch domainStrategy {
+	case dns.DomainStrategyUseIPv4:
+		destinationAddresses = common.Filter(destinationAddresses, netip.Addr.Is4)
+		if len(destinationAddresses) == 0 {
+			return nil, E.New("no IPv4 address available for ", destination)
+		}
+	case dns.DomainStrategyUseIPv6:
+		destinationAddresses = common.Filter(destinationAddresses, netip.Addr.Is6)
+		if len(destinationAddresses) == 0 {
+			return nil, E.New("no IPv6 address available for ", destination)
+		}
+	}
+	return dialer.DialParallelNetwork(ctx, h.dialer, network, destination, destinationAddresses, domainStrategy == dns.DomainStrategyPreferIPv6, h.networkStrategy, h.fallbackDelay)
+}
+
+func (h *Outbound) DialParallelNetwork(ctx context.Context, network string, destination M.Socksaddr, destinationAddresses []netip.Addr, networkStrategy C.NetworkStrategy, fallbackDelay time.Duration) (net.Conn, error) {
+	ctx, metadata := adapter.ExtendContext(ctx)
+	metadata.Outbound = h.Tag()
+	metadata.Destination = destination
+	switch h.overrideOption {
+	case 1, 2:
+		// override address
+		return h.DialContext(ctx, network, destination)
+	case 3:
+		destination.Port = h.overrideDestination.Port
+	}
+	network = N.NetworkName(network)
+	switch network {
+	case N.NetworkTCP:
+		h.logger.InfoContext(ctx, "outbound connection to ", destination)
+	case N.NetworkUDP:
+		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
+	}
+	var domainStrategy dns.DomainStrategy
+	if h.domainStrategy != dns.DomainStrategyAsIS {
+		domainStrategy = h.domainStrategy
+	} else {
+		domainStrategy = dns.DomainStrategy(metadata.InboundOptions.DomainStrategy)
+	}
+	switch domainStrategy {
+	case dns.DomainStrategyUseIPv4:
+		destinationAddresses = common.Filter(destinationAddresses, netip.Addr.Is4)
+		if len(destinationAddresses) == 0 {
+			return nil, E.New("no IPv4 address available for ", destination)
+		}
+	case dns.DomainStrategyUseIPv6:
+		destinationAddresses = common.Filter(destinationAddresses, netip.Addr.Is6)
+		if len(destinationAddresses) == 0 {
+			return nil, E.New("no IPv6 address available for ", destination)
+		}
+	}
+	return dialer.DialParallelNetwork(ctx, h.dialer, network, destination, destinationAddresses, domainStrategy == dns.DomainStrategyPreferIPv6, networkStrategy, fallbackDelay)
+}
+
+func (h *Outbound) ListenSerialNetworkPacket(ctx context.Context, destination M.Socksaddr, destinationAddresses []netip.Addr, networkStrategy C.NetworkStrategy, fallbackDelay time.Duration) (net.PacketConn, netip.Addr, error) {
+	ctx, metadata := adapter.ExtendContext(ctx)
+	metadata.Outbound = h.Tag()
+	metadata.Destination = destination
+	switch h.overrideOption {
+	case 1:
+		destination = h.overrideDestination
+	case 2:
+		newDestination := h.overrideDestination
+		newDestination.Port = destination.Port
+		destination = newDestination
+	case 3:
+		destination.Port = h.overrideDestination.Port
+	}
+	if h.overrideOption == 0 {
+		h.logger.InfoContext(ctx, "outbound packet connection")
+	} else {
+		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
+	}
+	conn, newDestination, err := dialer.ListenSerialNetworkPacket(ctx, h.dialer, destination, destinationAddresses, networkStrategy, fallbackDelay)
+	if err != nil {
+		return nil, netip.Addr{}, err
+	}
+	return conn, newDestination, nil
+}
+
 /*func (h *Outbound) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
 	if h.loopBack.CheckConn(metadata.Source.AddrPort(), M.AddrPortFromNet(conn.LocalAddr())) {
 		return E.New("reject loopback connection to ", metadata.Destination)

protocol/socks/outbound.go

@@ -10,7 +10,6 @@ import (
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
-	"github.com/sagernet/sing-dns"
 	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/logger"
@@ -115,23 +114,3 @@ func (h *Outbound) ListenPacket(ctx context.Context, destination M.Socksaddr) (n
 	h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
 	return h.client.ListenPacket(ctx, destination)
 }
-
-// TODO
-// Deprecated
-func (h *Outbound) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
-	if h.resolve {
-		return outbound.NewDirectConnection(ctx, h.router, h, conn, metadata, dns.DomainStrategyUseIPv4)
-	} else {
-		return outbound.NewConnection(ctx, h, conn, metadata)
-	}
-}
-
-// TODO
-// Deprecated
-func (h *Outbound) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
-	if h.resolve {
-		return outbound.NewDirectPacketConnection(ctx, h.router, h, conn, metadata, dns.DomainStrategyUseIPv4)
-	} else {
-		return outbound.NewPacketConnection(ctx, h, conn, metadata)
-	}
-}

protocol/wireguard/outbound.go

@@ -16,7 +16,6 @@ import (
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
 	"github.com/sagernet/sing-box/transport/wireguard"
-	"github.com/sagernet/sing-dns"
 	"github.com/sagernet/sing-tun"
 	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
@@ -231,15 +230,3 @@ func (w *Outbound) ListenPacket(ctx context.Context, destination M.Socksaddr) (n
 	}
 	return w.tunDevice.ListenPacket(ctx, destination)
 }
-
-// TODO
-// Deprecated
-func (w *Outbound) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
-	return outbound.NewDirectConnection(ctx, w.router, w, conn, metadata, dns.DomainStrategyAsIS)
-}
-
-// TODO
-// Deprecated
-func (w *Outbound) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
-	return outbound.NewDirectPacketConnection(ctx, w.router, w, conn, metadata, dns.DomainStrategyAsIS)
-}

route/network.go

@@ -8,6 +8,7 @@ import (
 	"runtime"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/common/conntrack"
@@ -38,8 +39,7 @@ type NetworkManager struct {
 	networkInterfaces atomic.TypedValue[[]adapter.NetworkInterface]
 
 	autoDetectInterface    bool
-	defaultInterface       string
+	defaultOptions         adapter.NetworkOptions
-	defaultMark            uint32
 	autoRedirectOutputMark uint32
 
 	networkMonitor    tun.NetworkUpdateMonitor
@@ -58,12 +58,24 @@ func NewNetworkManager(ctx context.Context, logger logger.ContextLogger, routeOp
 		logger:              logger,
 		interfaceFinder:     control.NewDefaultInterfaceFinder(),
 		autoDetectInterface: routeOptions.AutoDetectInterface,
-		defaultInterface:    routeOptions.DefaultInterface,
+		defaultOptions: adapter.NetworkOptions{
-		defaultMark:         routeOptions.DefaultMark,
+			DefaultInterface:       routeOptions.DefaultInterface,
+			DefaultMark:            routeOptions.DefaultMark,
+			DefaultNetworkStrategy: C.NetworkStrategy(routeOptions.DefaultNetworkStrategy),
+			DefaultFallbackDelay:   time.Duration(routeOptions.DefaultFallbackDelay),
+		},
 		pauseManager:      service.FromContext[pause.Manager](ctx),
 		platformInterface: service.FromContext[platform.Interface](ctx),
 		outboundManager:   service.FromContext[adapter.OutboundManager](ctx),
 	}
+	if C.NetworkStrategy(routeOptions.DefaultNetworkStrategy) != C.NetworkStrategyDefault {
+		if routeOptions.DefaultInterface != "" {
+			return nil, E.New("`default_network_strategy` is conflict with `default_interface`")
+		}
+		if !routeOptions.AutoDetectInterface {
+			return nil, E.New("`auto_detect_interface` is required by `default_network_strategy`")
+		}
+	}
 	usePlatformDefaultInterfaceMonitor := nm.platformInterface != nil
 	enforceInterfaceMonitor := routeOptions.AutoDetectInterface
 	if !usePlatformDefaultInterfaceMonitor {
@@ -84,12 +96,12 @@ func NewNetworkManager(ctx context.Context, logger logger.ContextLogger, routeOp
 			if err != nil {
 				return nil, E.New("auto_detect_interface unsupported on current platform")
 			}
-			interfaceMonitor.RegisterCallback(nm.notifyNetworkUpdate)
+			interfaceMonitor.RegisterCallback(nm.notifyInterfaceUpdate)
 			nm.interfaceMonitor = interfaceMonitor
 		}
 	} else {
 		interfaceMonitor := nm.platformInterface.CreateDefaultInterfaceMonitor(logger)
-		interfaceMonitor.RegisterCallback(nm.notifyNetworkUpdate)
+		interfaceMonitor.RegisterCallback(nm.notifyInterfaceUpdate)
 		nm.interfaceMonitor = interfaceMonitor
 	}
 	return nm, nil
@@ -265,10 +277,6 @@ func (r *NetworkManager) NetworkInterfaces() []adapter.NetworkInterface {
 	return r.networkInterfaces.Load()
 }
 
-func (r *NetworkManager) DefaultInterface() string {
-	return r.defaultInterface
-}
-
 func (r *NetworkManager) AutoDetectInterface() bool {
 	return r.autoDetectInterface
 }
@@ -301,8 +309,19 @@ func (r *NetworkManager) AutoDetectInterfaceFunc() control.Func {
 	}
 }
 
-func (r *NetworkManager) DefaultMark() uint32 {
+func (r *NetworkManager) ProtectFunc() control.Func {
-	return r.defaultMark
+	if r.platformInterface != nil && r.platformInterface.UsePlatformAutoDetectInterfaceControl() {
+		return func(network, address string, conn syscall.RawConn) error {
+			return control.Raw(conn, func(fd uintptr) error {
+				return r.platformInterface.AutoDetectInterfaceControl(int(fd))
+			})
+		}
+	}
+	return nil
+}
+
+func (r *NetworkManager) DefaultOptions() adapter.NetworkOptions {
+	return r.defaultOptions
 }
 
 func (r *NetworkManager) RegisterAutoRedirectOutputMark(mark uint32) error {
@@ -344,16 +363,14 @@ func (r *NetworkManager) ResetNetwork() {
 	}
 }
 
-func (r *NetworkManager) notifyNetworkUpdate(event int) {
+func (r *NetworkManager) notifyInterfaceUpdate(defaultInterface *control.Interface, flags int) {
-	if event == tun.EventNoRoute {
+	if defaultInterface == nil {
 		r.pauseManager.NetworkPause()
 		r.logger.Error("missing default interface")
-	} else {
+		return
-		r.pauseManager.NetworkWake()
-		defaultInterface := r.DefaultNetworkInterface()
-		if defaultInterface == nil {
-			panic("invalid interface context")
 	}
+
+	r.pauseManager.NetworkWake()
 	var options []string
 	options = append(options, F.ToString("index ", defaultInterface.Index))
 	if C.IsAndroid && r.platformInterface == nil {
@@ -364,14 +381,19 @@ func (r *NetworkManager) notifyNetworkUpdate(event int) {
 			vpnStatus = "disabled"
 		}
 		options = append(options, "vpn "+vpnStatus)
-		} else {
+	} else if r.platformInterface != nil {
-			if defaultInterface.Type != "" {
+		networkInterface := common.Find(r.networkInterfaces.Load(), func(it adapter.NetworkInterface) bool {
-				options = append(options, F.ToString("type ", defaultInterface.Type))
+			return it.Interface.Index == defaultInterface.Index
+		})
+		if networkInterface.Type == "" {
+			// race
+			return
 		}
-			if defaultInterface.Expensive {
+		options = append(options, F.ToString("type ", networkInterface.Type))
+		if networkInterface.Expensive {
 			options = append(options, "expensive")
 		}
-			if defaultInterface.Constrained {
+		if networkInterface.Constrained {
 			options = append(options, "constrained")
 		}
 	}
@@ -385,7 +407,6 @@ func (r *NetworkManager) notifyNetworkUpdate(event int) {
 			}
 		}
 	}
-	}
 
 	if !r.started {
 		return

route/route.go

@@ -424,9 +424,13 @@ match:
 		}
 		switch action := currentRule.Action().(type) {
 		case *rule.RuleActionRoute:
+			metadata.NetworkStrategy = action.NetworkStrategy
+			metadata.FallbackDelay = action.FallbackDelay
 			metadata.UDPDisableDomainUnmapping = action.UDPDisableDomainUnmapping
 			metadata.UDPConnect = action.UDPConnect
 		case *rule.RuleActionRouteOptions:
+			metadata.NetworkStrategy = action.NetworkStrategy
+			metadata.FallbackDelay = action.FallbackDelay
 			metadata.UDPDisableDomainUnmapping = action.UDPDisableDomainUnmapping
 			metadata.UDPConnect = action.UDPConnect
 		case *rule.RuleActionSniff:

route/rule/rule_action.go

@@ -30,12 +30,16 @@ func NewRuleAction(ctx context.Context, logger logger.ContextLogger, action opti
 		return &RuleActionRoute{
 			Outbound: action.RouteOptions.Outbound,
 			RuleActionRouteOptions: RuleActionRouteOptions{
+				NetworkStrategy:           C.NetworkStrategy(action.RouteOptions.NetworkStrategy),
+				FallbackDelay:             time.Duration(action.RouteOptions.FallbackDelay),
 				UDPDisableDomainUnmapping: action.RouteOptions.UDPDisableDomainUnmapping,
 				UDPConnect:                action.RouteOptions.UDPConnect,
 			},
 		}, nil
 	case C.RuleActionTypeRouteOptions:
 		return &RuleActionRouteOptions{
+			NetworkStrategy:           C.NetworkStrategy(action.RouteOptionsOptions.NetworkStrategy),
+			FallbackDelay:             time.Duration(action.RouteOptionsOptions.FallbackDelay),
 			UDPDisableDomainUnmapping: action.RouteOptionsOptions.UDPDisableDomainUnmapping,
 			UDPConnect:                action.RouteOptionsOptions.UDPConnect,
 		}, nil
@@ -135,6 +139,8 @@ func (r *RuleActionRoute) String() string {
 }
 
 type RuleActionRouteOptions struct {
+	NetworkStrategy           C.NetworkStrategy
+	FallbackDelay             time.Duration
 	UDPDisableDomainUnmapping bool
 	UDPConnect                bool
 }

transport/dhcp/server.go

@@ -166,7 +166,7 @@ func (t *Transport) updateServers() error {
 	}
 }
 
-func (t *Transport) interfaceUpdated(int) {
+func (t *Transport) interfaceUpdated(defaultInterface *control.Interface, flags int) {
 	err := t.updateServers()
 	if err != nil {
 		t.options.Logger.Error("update servers: ", err)