kindnetd remove wrong routes

images/kindnetd/cmd/kindnetd/main.go

@@ -261,12 +261,12 @@ func makeNodesReconciler(cniConfig *CNIConfigWriter, hostIP string, ipFamily IPF
 		}
 
 		if nodeIPv4 != "" && len(podCIDRsv4) > 0 {
-			if err := syncRoute(nodeIPv4, podCIDRsv4); err != nil {
+			if err := syncRoutes(nodeIPv4, podCIDRsv4); err != nil {
 				return err
 			}
 		}
 		if nodeIPv6 != "" && len(podCIDRsv6) > 0 {
-			if err := syncRoute(nodeIPv6, podCIDRsv6); err != nil {
+			if err := syncRoutes(nodeIPv6, podCIDRsv6); err != nil {
 				return err
 			}
 		}

images/kindnetd/cmd/kindnetd/routes.go

@@ -24,30 +24,49 @@ import (
 	"k8s.io/klog/v2"
 )
 
-func syncRoute(nodeIP string, podCIDRs []string) error {
+func syncRoutes(nodeIP string, podCIDRs []string) error {
 	ip := net.ParseIP(nodeIP)
-
 	for _, podCIDR := range podCIDRs {
-		// parse subnet
-		dst, err := netlink.ParseIPNet(podCIDR)
-		if err != nil {
+		if err := syncRoute(podCIDR, ip); err != nil {
 			return err
 		}
+	}
+	return nil
+}
 
-		// Check if the route exists to the other node's PodCIDR
-		routeToDst := netlink.Route{Dst: dst, Gw: ip}
-		route, err := netlink.RouteListFiltered(nl.GetIPFamily(ip), &routeToDst, netlink.RT_FILTER_DST)
-		if err != nil {
-			return err
+func syncRoute(podCIDR string, gw net.IP) error {
+	// parse subnet
+	dst, err := netlink.ParseIPNet(podCIDR)
+	if err != nil {
+		return err
+	}
+
+	// List all routes to the other node's PodCIDR
+	routeToDst := netlink.Route{Dst: dst, Gw: gw}
+	routes, err := netlink.RouteListFiltered(nl.GetIPFamily(gw), &routeToDst, netlink.RT_FILTER_DST)
+	if err != nil {
+		return err
+	}
+
+	// Check if the route exists to the other node's PodCIDR and delete invalid routes
+	for _, route := range routes {
+		// Skip creation of a route if there is gateway matches the expected.
+		if route.Gw.Equal(gw) {
+			return nil
 		}
 
-		// Add route if not present
-		if len(route) == 0 {
-			klog.Infof("Adding route %v \n", routeToDst)
-			if err := netlink.RouteAdd(&routeToDst); err != nil {
-				return err
-			}
+		// Delete wrong route because of invalid gateway.
+		klog.Infof("Removing invalid route %v\n", route)
+		if err := netlink.RouteDel(&route); err != nil {
+			return err
 		}
 	}
+
+	// Add route if not present
+	klog.Infof("Adding route %v \n", routeToDst)
+	if err := netlink.RouteAdd(&routeToDst); err != nil {
+		return err
+	}
+
 	return nil
 }