Add functions to separate ipv4 from ipv6 functions

pkg/util/net.go

@@ -63,3 +63,25 @@ func GetFirst4String(elems []string) (string, error) {
 	}
 	return ip.String(), nil
 }
+
+// JoinIP4Nets stringifies and joins a list of IPv4 networks with commas.
+func JoinIP4Nets(elems []*net.IPNet) string {
+	var strs []string
+	for _, elem := range elems {
+		if elem != nil && elem.IP.To4() != nil {
+			strs = append(strs, elem.String())
+		}
+	}
+	return strings.Join(strs, ",")
+}
+
+// JoinIP6Nets stringifies and joins a list of IPv6 networks with commas.
+func JoinIP6Nets(elems []*net.IPNet) string {
+	var strs []string
+	for _, elem := range elems {
+		if elem != nil && elem.IP.To4() == nil {
+			strs = append(strs, elem.String())
+		}
+	}
+	return strings.Join(strs, ",")
+}