fix(NRC): error when nec. host IP not found

If we can't find an appropriate IP to add for nextHop to injectRoute or
overlay tunnel, raise error rather than trying to continue.

pkg/controllers/routing/network_routes_controller.go

@@ -649,14 +649,18 @@ func (nrc *NetworkRoutingController) injectRoute(path *gobgpapi.Path) error {
 
 	switch {
 	case link != nil:
-		// if we setup an overlay tunnel link, then use it for destination routing
+		// if we set up an overlay tunnel link, then use it for destination routing
 		var bestIPForFamily net.IP
 		if dst.IP.To4() != nil {
 			bestIPForFamily = utils.FindBestIPv4NodeAddress(nrc.primaryIP, nrc.nodeIPv4Addrs)
 		} else {
 			// Need to activate the ip command in IPv6 mode
 			bestIPForFamily = utils.FindBestIPv6NodeAddress(nrc.primaryIP, nrc.nodeIPv6Addrs)
 		}
+		if bestIPForFamily == nil {
+			return fmt.Errorf("not able to find an appropriate configured IP address on node for destination "+
+				"IP family: %s", dst.String())
+		}
 		route = &netlink.Route{
 			LinkIndex: link.Attrs().Index,
 			Src:       bestIPForFamily,
@@ -734,6 +738,10 @@ func (nrc *NetworkRoutingController) setupOverlayTunnel(tunnelName string, nextH
 		bestIPForFamily = utils.FindBestIPv6NodeAddress(nrc.primaryIP, nrc.nodeIPv6Addrs)
 		ipipMode = "ip6ip6"
 	}
+	if nil == bestIPForFamily {
+		return nil, fmt.Errorf("not able to find an appropriate configured IP address on node for destination "+
+			"IP family: %s", nextHop.String())
+	}
 
 	// an error here indicates that the tunnel didn't exist, so we need to create it, if it already exists there's
 	// nothing to do here