Improve add windows route

Author: nekohasekai

tun_windows.go

@@ -172,15 +172,9 @@ func (t *NativeTun) Start() error {
 	if err != nil {
 		return err
 	}
-	for _, routeRange := range routeRanges {
-		if routeRange.Addr().Is4() {
-			err = luid.AddRoute(routeRange, gateway4, 0)
-		} else {
-			err = luid.AddRoute(routeRange, gateway6, 0)
-		}
-		if err != nil {
-			return err
-		}
+	err = addRouteList(luid, routeRanges, gateway4, gateway6, 0)
+	if err != nil {
+		return err
 	}
 	err = windnsapi.FlushResolverCache()
 	if err != nil {
@@ -560,20 +554,45 @@ func (t *NativeTun) UpdateRouteOptions(tunOptions Options) error {
 	if err != nil {
 		return err
 	}
-	for _, routeRange := range routeRanges {
-		if routeRange.Addr().Is4() {
-			err = luid.AddRoute(routeRange, gateway4, 0)
+	err = addRouteList(luid, routeRanges, gateway4, gateway6, 0)
+	if err != nil {
+		return err
+	}
+	err = windnsapi.FlushResolverCache()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func addRouteList(luid winipcfg.LUID, destinations []netip.Prefix, gateway4 netip.Addr, gateway6 netip.Addr, metric uint32) error {
+	row := winipcfg.MibIPforwardRow2{}
+	row.Init()
+	row.InterfaceLUID = luid
+	row.Metric = metric
+	nextHop4 := row.NextHop
+	nextHop6 := row.NextHop
+	if gateway4.IsValid() {
+		nextHop4.SetAddr(gateway4)
+	}
+	if gateway6.IsValid() {
+		nextHop6.SetAddr(gateway6)
+	}
+	for _, destination := range destinations {
+		err := row.DestinationPrefix.SetPrefix(destination)
+		if err != nil {
+			return err
+		}
+		if destination.Addr().Is4() {
+			row.NextHop = nextHop4
 		} else {
-			err = luid.AddRoute(routeRange, gateway6, 0)
+			row.NextHop = nextHop6
 		}
+		err = row.Create()
 		if err != nil {
 			return err
 		}
 	}
-	err = windnsapi.FlushResolverCache()
-	if err != nil {
-		return err
-	}
 	return nil
 }