chore: dialer will consider the routing of the local interface when auto-detect-interface in tun is enabled

wwqgtxx · wwqgtxx · commit 4bd3ae52bd88 · 2025-03-10T10:45:31.000+08:00
for MetaCubeX#1881 MetaCubeX#1819
diff --git a/component/dialer/dialer.go b/component/dialer/dialer.go
@@ -88,6 +88,15 @@ func ListenPacket(ctx context.Context, network, address string, rAddrPort netip.
 	if DefaultSocketHook != nil { // ignore interfaceName, routingMark when DefaultSocketHook not null (in CMFA)
 		socketHookToListenConfig(lc)
 	} else {
+		if cfg.interfaceName == "" {
+			if finder := DefaultInterfaceFinder.Load(); finder != nil {
+				cfg.interfaceName = finder.FindInterfaceName(rAddrPort.Addr())
+			}
+		}
+		if rAddrPort.Addr().Unmap().IsLoopback() {
+			// avoid "The requested address is not valid in its context."
+			cfg.interfaceName = ""
+		}
 		if cfg.interfaceName != "" {
 			bind := bindIfaceToListenConfig
 			if cfg.fallbackBind {
@@ -153,6 +162,11 @@ func dialContext(ctx context.Context, network string, destination netip.Addr, po
 	if DefaultSocketHook != nil { // ignore interfaceName, routingMark and tfo when DefaultSocketHook not null (in CMFA)
 		socketHookToToDialer(dialer)
 	} else {
+		if opt.interfaceName == "" {
+			if finder := DefaultInterfaceFinder.Load(); finder != nil {
+				opt.interfaceName = finder.FindInterfaceName(destination)
+			}
+		}
 		if opt.interfaceName != "" {
 			bind := bindIfaceToDialer
 			if opt.fallbackBind {
@@ -373,12 +387,7 @@ func (d Dialer) DialContext(ctx context.Context, network, address string) (net.C
 }
 
 func (d Dialer) ListenPacket(ctx context.Context, network, address string, rAddrPort netip.AddrPort) (net.PacketConn, error) {
-	opt := d.Opt // make a copy
-	if rAddrPort.Addr().Unmap().IsLoopback() {
-		// avoid "The requested address is not valid in its context."
-		WithInterface("")(&opt)
-	}
-	return ListenPacket(ctx, ParseNetwork(network, rAddrPort.Addr()), address, rAddrPort, WithOption(opt))
+	return ListenPacket(ctx, ParseNetwork(network, rAddrPort.Addr()), address, rAddrPort, WithOption(d.Opt))
 }
 
 func NewDialer(options ...Option) Dialer {
diff --git a/component/dialer/options.go b/component/dialer/options.go
@@ -3,6 +3,7 @@ package dialer
 import (
 	"context"
 	"net"
+	"net/netip"
 
 	"github.com/metacubex/mihomo/common/atomic"
 	"github.com/metacubex/mihomo/component/resolver"
@@ -12,8 +13,14 @@ var (
 	DefaultOptions     []Option
 	DefaultInterface   = atomic.NewTypedValue[string]("")
 	DefaultRoutingMark = atomic.NewInt32(0)
+
+	DefaultInterfaceFinder = atomic.NewTypedValue[InterfaceFinder](nil)
 )
 
+type InterfaceFinder interface {
+	FindInterfaceName(destination netip.Addr) string
+}
+
 type NetDialer interface {
 	DialContext(ctx context.Context, network, address string) (net.Conn, error)
 }
diff --git a/listener/listener.go b/listener/listener.go
@@ -512,9 +512,6 @@ func ReCreateTun(tunConf LC.Tun, tunnel C.Tunnel) {
 	}()
 
 	if tunConf.Equal(LastTunConf) {
-		if tunLister != nil {
-			tunLister.FlushDefaultInterface()
-		}
 		return
 	}
 
diff --git a/listener/sing_tun/server.go b/listener/sing_tun/server.go
@@ -52,6 +52,8 @@ type Listener struct {
 	autoRedirect            tun.AutoRedirect
 	autoRedirectOutputMark  int32
 
+	cDialerInterfaceFinder dialer.InterfaceFinder
+
 	ruleUpdateCallbackCloser io.Closer
 	ruleUpdateMutex          sync.Mutex
 	routeAddressMap          map[string]*netipx.IPSet
@@ -290,13 +292,25 @@ func New(options LC.Tun, tunnel C.Tunnel, additions ...inbound.Addition) (l *Lis
 		}
 		l.defaultInterfaceMonitor = defaultInterfaceMonitor
 		defaultInterfaceMonitor.RegisterCallback(func(event int) {
-			l.FlushDefaultInterface()
+			iface.FlushCache()
+			resolver.ResetConnection() // reset resolver's connection after default interface changed
 		})
 		err = defaultInterfaceMonitor.Start()
 		if err != nil {
 			err = E.Cause(err, "start DefaultInterfaceMonitor")
 			return
 		}
+
+		if options.AutoDetectInterface {
+			l.cDialerInterfaceFinder = &cDialerInterfaceFinder{
+				tunName:                 tunName,
+				defaultInterfaceMonitor: defaultInterfaceMonitor,
+			}
+			if !dialer.DefaultInterfaceFinder.CompareAndSwap(nil, l.cDialerInterfaceFinder) {
+				err = E.New("don't allowed two tun listener using auto-detect-interface")
+				return
+			}
+		}
 	}
 
 	tunOptions := tun.Options{
@@ -503,27 +517,25 @@ func (l *Listener) updateRule(ruleProvider provider.RuleProvider, exclude bool,
 	}
 }
 
-func (l *Listener) FlushDefaultInterface() {
-	if l.options.AutoDetectInterface && l.defaultInterfaceMonitor != nil {
-		for _, destination := range []netip.Addr{netip.IPv4Unspecified(), netip.IPv6Unspecified(), netip.MustParseAddr("1.1.1.1")} {
-			autoDetectInterfaceName := l.defaultInterfaceMonitor.DefaultInterfaceName(destination)
-			if autoDetectInterfaceName == l.tunName {
-				log.Warnln("[TUN] Auto detect interface by %s get same name with tun", destination.String())
-			} else if autoDetectInterfaceName == "" || autoDetectInterfaceName == "<nil>" {
-				log.Warnln("[TUN] Auto detect interface by %s get empty name.", destination.String())
-			} else {
-				if old := dialer.DefaultInterface.Swap(autoDetectInterfaceName); old != autoDetectInterfaceName {
-					log.Warnln("[TUN] default interface changed by monitor, %s => %s", old, autoDetectInterfaceName)
-					iface.FlushCache()
-					resolver.ResetConnection() // reset resolver's connection after default interface changed
-				}
-				return
-			}
-		}
-		if dialer.DefaultInterface.CompareAndSwap("", "<invalid>") {
-			log.Warnln("[TUN] Auto detect interface failed, set '<invalid>' to DefaultInterface to avoid lookback")
+type cDialerInterfaceFinder struct {
+	tunName                 string
+	defaultInterfaceMonitor tun.DefaultInterfaceMonitor
+}
+
+func (d *cDialerInterfaceFinder) FindInterfaceName(destination netip.Addr) string {
+	for _, dest := range []netip.Addr{destination, netip.IPv4Unspecified(), netip.IPv6Unspecified()} {
+		autoDetectInterfaceName := d.defaultInterfaceMonitor.DefaultInterfaceName(dest)
+		if autoDetectInterfaceName == d.tunName {
+			log.Warnln("[TUN] Auto detect interface for %s get same name with tun", destination.String())
+		} else if autoDetectInterfaceName == "" || autoDetectInterfaceName == "<nil>" {
+			log.Warnln("[TUN] Auto detect interface for %s get empty name.", destination.String())
+		} else {
+			log.Debugln("[TUN] Auto detect interface for %s --> %s", destination, autoDetectInterfaceName)
+			return autoDetectInterfaceName
 		}
 	}
+	log.Warnln("[TUN] Auto detect interface for %s failed, return '<invalid>' to avoid lookback", destination)
+	return "<invalid>"
 }
 
 func uidToRange(uidList []uint32) []ranges.Range[uint32] {
@@ -564,6 +576,9 @@ func (l *Listener) Close() error {
 	if l.autoRedirectOutputMark != 0 {
 		dialer.DefaultRoutingMark.CompareAndSwap(l.autoRedirectOutputMark, 0)
 	}
+	if l.cDialerInterfaceFinder != nil {
+		dialer.DefaultInterfaceFinder.CompareAndSwap(l.cDialerInterfaceFinder, nil)
+	}
 	return common.Close(
 		l.ruleUpdateCallbackCloser,
 		l.tunStack,
diff --git a/transport/hysteria/conns/faketcp/tcp_linux.go b/transport/hysteria/conns/faketcp/tcp_linux.go
@@ -404,8 +404,14 @@ func Dial(network, address string) (*TCPConn, error) {
 
 	var lTcpAddr *net.TCPAddr
 	var lIpAddr *net.IPAddr
-	if ifaceName := dialer.DefaultInterface.Load(); len(ifaceName) > 0 {
-		rAddrPort := raddr.AddrPort()
+	rAddrPort := raddr.AddrPort()
+	ifaceName := dialer.DefaultInterface.Load()
+	if ifaceName == "" {
+		if finder := dialer.DefaultInterfaceFinder.Load(); finder != nil {
+			ifaceName = finder.FindInterfaceName(rAddrPort.Addr())
+		}
+	}
+	if len(ifaceName) > 0 {
 		addr, err := dialer.LookupLocalAddrFromIfaceName(ifaceName, network, rAddrPort.Addr(), int(rAddrPort.Port()))
 		if err != nil {
 			return nil, err

Original file line number	Diff line number	Diff line change
`@@ -512,9 +512,6 @@ func ReCreateTun(tunConf LC.Tun, tunnel C.Tunnel) {`
`512`	`512`	`}()`
`513`	`513`
`514`	`514`	`if tunConf.Equal(LastTunConf) {`
`515`		`- if tunLister != nil {`
`516`		`- tunLister.FlushDefaultInterface()`
`517`		`- }`
`518`	`515`	`return`
`519`	`516`	`}`
`520`	`517`