improve IAM module

Signed-off-by: hongming <talonwan@yunify.com>

vendor/k8s.io/apiserver/pkg/server/config_selfclient.go

@@ -21,6 +21,7 @@ import (
 	"net"
 
 	restclient "k8s.io/client-go/rest"
+	netutils "k8s.io/utils/net"
 )
 
 // LoopbackClientServerNameOverride is passed to the apiserver from the loopback client in order to
@@ -70,23 +71,27 @@ func LoopbackHostPort(bindAddress string) (string, string, error) {
 		return "", "", fmt.Errorf("invalid server bind address: %q", bindAddress)
 	}
 
-	isIPv6 := net.ParseIP(host).To4() == nil
+	isIPv6 := netutils.IsIPv6String(host)
 
 	// Value is expected to be an IP or DNS name, not "0.0.0.0".
 	if host == "0.0.0.0" || host == "::" {
-		host = "localhost"
 		// Get ip of local interface, but fall back to "localhost".
 		// Note that "localhost" is resolved with the external nameserver first with Go's stdlib.
 		// So if localhost.<yoursearchdomain> resolves, we don't get a 127.0.0.1 as expected.
-		addrs, err := net.InterfaceAddrs()
-		if err == nil {
-			for _, address := range addrs {
-				if ipnet, ok := address.(*net.IPNet); ok && ipnet.IP.IsLoopback() && isIPv6 == (ipnet.IP.To4() == nil) {
-					host = ipnet.IP.String()
-					break
-				}
-			}
-		}
+		host = getLoopbackAddress(isIPv6)
 	}
 	return host, port, nil
 }
+
+// getLoopbackAddress returns the ip address of local loopback interface. If any error occurs or loopback interface is not found, will fall back to "localhost"
+func getLoopbackAddress(wantIPv6 bool) string {
+	addrs, err := net.InterfaceAddrs()
+	if err == nil {
+		for _, address := range addrs {
+			if ipnet, ok := address.(*net.IPNet); ok && ipnet.IP.IsLoopback() && wantIPv6 == netutils.IsIPv6(ipnet.IP) {
+				return ipnet.IP.String()
+			}
+		}
+	}
+	return "localhost"
+}