enhance unit test and logging (#3374)

* enhance unit test and logging

* enhance logging message

* fix unit test

* make code clean

Author: beiwei30

dubbo-common/src/main/java/org/apache/dubbo/common/utils/NetUtils.java

@@ -346,25 +346,24 @@ public static String toURL(String protocol, String host, int port, String path)
     }
 
     public static void joinMulticastGroup (MulticastSocket multicastSocket, InetAddress multicastAddress) throws IOException {
-        setInterface(multicastSocket, multicastAddress);
+        setInterface(multicastSocket, multicastAddress instanceof Inet6Address);
         multicastSocket.setLoopbackMode(false);
         multicastSocket.joinGroup(multicastAddress);
     }
 
-    public static void setInterface (MulticastSocket multicastSocket, InetAddress multicastAddress) throws IOException{
+    public static void setInterface (MulticastSocket multicastSocket, boolean preferIpv6) throws IOException{
         boolean interfaceSet = false;
-        boolean ipV6 = multicastAddress instanceof Inet6Address;
         Enumeration interfaces = NetworkInterface.getNetworkInterfaces();
         while (interfaces.hasMoreElements()) {
             NetworkInterface i = (NetworkInterface) interfaces.nextElement();
             Enumeration addresses = i.getInetAddresses();
             while (addresses.hasMoreElements()) {
                 InetAddress address = (InetAddress) addresses.nextElement();
-                if (ipV6 && address instanceof Inet6Address) {
+                if (preferIpv6 && address instanceof Inet6Address) {
                     multicastSocket.setInterface(address);
                     interfaceSet = true;
                     break;
-                } else if (!ipV6 && address instanceof Inet4Address) {
+                } else if (!preferIpv6 && address instanceof Inet4Address) {
                     multicastSocket.setInterface(address);
                     interfaceSet = true;
                     break;
@@ -376,4 +375,4 @@ public static void setInterface (MulticastSocket multicastSocket, InetAddress mu
         }
     }
 
-}
+}

dubbo-registry/dubbo-registry-multicast/src/main/java/org/apache/dubbo/registry/multicast/MulticastRegistry.java

@@ -31,6 +31,7 @@
 
 import java.io.IOException;
 import java.net.DatagramPacket;
+import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.MulticastSocket;
@@ -81,9 +82,8 @@ public MulticastRegistry(URL url) {
         }
         try {
             multicastAddress = InetAddress.getByName(url.getHost());
-            if (!multicastAddress.isMulticastAddress()) {
-                throw new IllegalArgumentException("Invalid multicast address " + url.getHost() + ", ipv4 multicast address scope: 224.0.0.0 - 239.255.255.255.");
-            }
+            checkMulticastAddress(multicastAddress);
+
             multicastPort = url.getPort() <= 0 ? DEFAULT_MULTICAST_PORT : url.getPort();
             multicastSocket = new MulticastSocket(multicastPort);
             NetUtils.joinMulticastGroup(multicastSocket, multicastAddress);
@@ -132,6 +132,19 @@ public void run() {
         }
     }
 
+    private void checkMulticastAddress(InetAddress multicastAddress) {
+        if (!multicastAddress.isMulticastAddress()) {
+            String message = "Invalid multicast address " + multicastAddress;
+            if (!(multicastAddress instanceof Inet4Address)) {
+                throw new IllegalArgumentException(message + ", " +
+                        "ipv4 multicast address scope: 224.0.0.0 - 239.255.255.255.");
+            } else {
+                throw new IllegalArgumentException(message + ", " + "ipv6 multicast address must start with ff, " +
+                        "for example: ff01::1");
+            }
+        }
+    }
+
     /**
      * Remove the expired providers, only when "clean" parameter is true.
      */

dubbo-registry/dubbo-registry-multicast/src/test/java/org/apache/dubbo/registry/multicast/MulticastRegistryTest.java

@@ -227,34 +227,35 @@ public void testMulticastAddress() {
         MulticastSocket multicastSocket = null;
         try {
             // ipv4 multicast address
-            try {
-                multicastAddress = InetAddress.getByName("224.55.66.77");
-                multicastSocket = new MulticastSocket(2345);
-                multicastSocket.setLoopbackMode(false);
-                NetUtils.setInterface(multicastSocket, multicastAddress);
-                multicastSocket.joinGroup(multicastAddress);
-            } finally {
-                if (multicastSocket != null) {
-                    multicastSocket.close();
-                }
+            multicastAddress = InetAddress.getByName("224.55.66.77");
+            multicastSocket = new MulticastSocket(2345);
+            multicastSocket.setLoopbackMode(false);
+            NetUtils.setInterface(multicastSocket, false);
+            multicastSocket.joinGroup(multicastAddress);
+        } catch (Exception e) {
+            Assertions.fail(e);
+        } finally {
+            if (multicastSocket != null) {
+                multicastSocket.close();
             }
+        }
 
-            // multicast ipv6 address,
-            /*try {
-                multicastAddress = InetAddress.getByName("ff01::1");
-                multicastSocket = new MulticastSocket();
-                multicastSocket.setLoopbackMode(false);
-                NetUtils.setInterface(multicastSocket, multicastAddress);
-                multicastSocket.joinGroup(multicastAddress);
-            } finally {
-                if (multicastSocket != null) {
-                    multicastSocket.close();
-                }
-            }*/
+        // multicast ipv6 address,
+        try {
+            multicastAddress = InetAddress.getByName("ff01::1");
 
-        } catch (Exception e) {
-            Assertions.fail(e);
+            multicastSocket = new MulticastSocket();
+            multicastSocket.setLoopbackMode(false);
+            NetUtils.setInterface(multicastSocket, true);
+            multicastSocket.joinGroup(multicastAddress);
+        } catch (Throwable t) {
+            t.printStackTrace();
+        } finally {
+            if (multicastSocket != null) {
+                multicastSocket.close();
+            }
         }
+
     }
 
 }