Feature: auto detect interface if switch network

listener/tun/ipstack/commons/router.go

@@ -3,11 +3,19 @@ package commons
 import (
 	"fmt"
 	"net"
+	"time"
+
+	"github.com/Dreamacro/clash/component/dialer"
+	"github.com/Dreamacro/clash/log"
 )
 
-var Routes = []string{"1.0.0.0/8", "2.0.0.0/7", "4.0.0.0/6", "8.0.0.0/5", "16.0.0.0/4", "32.0.0.0/3", "64.0.0.0/2", "128.0.0.0/1"}
+var (
+	defaultRoutes = []string{"1.0.0.0/8", "2.0.0.0/7", "4.0.0.0/6", "8.0.0.0/5", "16.0.0.0/4", "32.0.0.0/3", "64.0.0.0/2", "128.0.0.0/1"}
 
-func IPv4MaskString(bits int) string {
+	defaultInterfaceMonitorDuration = 20 * time.Second
+)
+
+func ipv4MaskString(bits int) string {
 	m := net.CIDRMask(bits, 32)
 	if len(m) != 4 {
 		panic("ipv4Mask: len must be 4 bytes")
@@ -15,3 +23,27 @@ func IPv4MaskString(bits int) string {
 
 	return fmt.Sprintf("%d.%d.%d.%d", m[0], m[1], m[2], m[3])
 }
+
+func defaultInterfaceChangeMonitor() {
+	t := time.NewTicker(defaultInterfaceMonitorDuration)
+	defer t.Stop()
+
+	for {
+		<-t.C
+
+		interfaceName, err := GetAutoDetectInterface()
+		if err != nil {
+			log.Warnln("[TUN] default interface monitor exited, cause: %v", err)
+			break
+		}
+
+		old := dialer.DefaultInterface.Load()
+		if interfaceName == old {
+			continue
+		}
+
+		dialer.DefaultInterface.Store(interfaceName)
+
+		log.Warnln("[TUN] default interface changed by monitor, %s => %s", old, interfaceName)
+	}
+}

listener/tun/ipstack/commons/router_darwin.go

@@ -9,7 +9,7 @@ import (
 )
 
 func GetAutoDetectInterface() (string, error) {
-	return cmd.ExecCmd("bash -c netstat -rnf inet | grep 'default' | awk -F ' ' 'NR==1{print $6}' | xargs echo -n")
+	return cmd.ExecCmd("bash -c route -n get default | grep 'interface:' | awk -F ' ' 'NR==1{print $2}' | xargs echo -n")
 }
 
 func ConfigInterfaceAddress(dev device.Device, addr netip.Prefix, forceMTU int, autoRoute bool) error {
@@ -21,7 +21,7 @@ func ConfigInterfaceAddress(dev device.Device, addr netip.Prefix, forceMTU int,
 		interfaceName = dev.Name()
 		ip            = addr.Masked().Addr().Next()
 		gw            = ip.Next()
-		netmask       = IPv4MaskString(addr.Bits())
+		netmask       = ipv4MaskString(addr.Bits())
 	)
 
 	cmdStr := fmt.Sprintf("ifconfig %s inet %s netmask %s %s", interfaceName, ip, netmask, gw)
@@ -44,7 +44,7 @@ func ConfigInterfaceAddress(dev device.Device, addr netip.Prefix, forceMTU int,
 
 func configInterfaceRouting(interfaceName string, addr netip.Prefix) error {
 	var (
-		routes  = append(Routes, addr.String())
+		routes  = append(defaultRoutes, addr.String())
 		gateway = addr.Masked().Addr().Next()
 	)
 
@@ -54,6 +54,8 @@ func configInterfaceRouting(interfaceName string, addr netip.Prefix) error {
 		}
 	}
 
+	go defaultInterfaceChangeMonitor()
+
 	return execRouterCmd("add", "-inet6", "2000::/3", interfaceName)
 }
 

listener/tun/ipstack/commons/router_linux.go

@@ -36,11 +36,14 @@ func ConfigInterfaceAddress(dev device.Device, addr netip.Prefix, forceMTU int,
 
 func configInterfaceRouting(interfaceName string, addr netip.Prefix) error {
 	linkIP := addr.Masked().Addr().Next()
-	for _, route := range Routes {
+	for _, route := range defaultRoutes {
 		if err := execRouterCmd("add", route, interfaceName, linkIP.String()); err != nil {
 			return err
 		}
 	}
+
+	go defaultInterfaceChangeMonitor()
+
 	return nil
 }
 

listener/tun/ipstack/commons/router_windows.go

@@ -15,6 +15,8 @@ import (
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 )
 
+var wintunInterfaceName string
+
 func GetAutoDetectInterface() (string, error) {
 	ifname, err := getAutoDetectInterfaceByFamily(winipcfg.AddressFamily(windows.AF_INET))
 	if err == nil {
@@ -30,7 +32,7 @@ func ConfigInterfaceAddress(dev device.Device, addr netip.Prefix, forceMTU int,
 	var err error
 startOver:
 	if tryTimes > 0 {
-		log.Infoln("Retrying interface configuration after failure because system just booted (T+%v): %v", windows.DurationSinceBoot(), err)
+		log.Infoln("[TUN] retrying interface configuration after failure because system just booted (T+%v): %v", windows.DurationSinceBoot(), err)
 		time.Sleep(time.Second)
 		retryOnFailure = retryOnFailure && tryTimes < 15
 	}
@@ -199,6 +201,10 @@ startOver:
 		return fmt.Errorf("unable to set DNS %s %s: %w", "198.18.0.2", "nil", err)
 	}
 
+	wintunInterfaceName = dev.Name()
+
+	go defaultInterfaceChangeMonitor()
+
 	return nil
 }
 
@@ -221,7 +227,7 @@ func cleanupAddressesOnDisconnectedInterfaces(family winipcfg.AddressFamily, add
 		for address := iface.FirstUnicastAddress; address != nil; address = address.Next {
 			if ip, _ := netip.AddrFromSlice(address.Address.IP()); addrHash[ip] {
 				prefix := netip.PrefixFrom(ip, int(address.OnLinkPrefixLength))
-				log.Infoln("Cleaning up stale address %s from interface ‘%s’", prefix.String(), iface.FriendlyName())
+				log.Infoln("[TUN] cleaning up stale address %s from interface ‘%s’", prefix.String(), iface.FriendlyName())
 				_ = iface.LUID.DeleteIPAddress(prefix)
 			}
 		}
@@ -248,6 +254,10 @@ func getAutoDetectInterfaceByFamily(family winipcfg.AddressFamily) (string, erro
 
 		ifname := iface.FriendlyName()
 
+		if wintunInterfaceName == ifname {
+			continue
+		}
+
 		for gatewayAddress := iface.FirstGatewayAddress; gatewayAddress != nil; gatewayAddress = gatewayAddress.Next {
 			nextHop, _ := netip.AddrFromSlice(gatewayAddress.Address.IP())