Merge 1176986 and 1177035 from trunk for HADOOP-7668.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1189976 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -412,6 +412,9 @@ Release 0.23.0 - Unreleased
     help in exception messages. (todd)
 
     HADOOP-7762. Common side of MR-2736. (eli)
+    
+    HADOOP-7668. Add a NetUtils method that can tell if an InetAddress 
+    belongs to local host. (suresh)
 
   OPTIMIZATIONS
   

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/NetUtils.java

@@ -559,6 +559,27 @@ public class NetUtils {
     } catch (UnknownHostException ignore) { }
     return addr;
   }
+  
+  /**
+   * Given an InetAddress, checks to see if the address is a local address, by
+   * comparing the address with all the interfaces on the node.
+   * @param addr address to check if it is local node's address
+   * @return true if the address corresponds to the local node
+   */
+  public static boolean isLocalAddress(InetAddress addr) {
+    // Check if the address is any local or loop back
+    boolean local = addr.isAnyLocalAddress() || addr.isLoopbackAddress();
+
+    // Check if the address is defined on any interface
+    if (!local) {
+      try {
+        local = NetworkInterface.getByInetAddress(addr) != null;
+      } catch (SocketException e) {
+        local = false;
+      }
+    }
+    return local;
+  }
 
   /**
    * Take an IOException , the local host port and remote host port details and

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/net/TestNetUtils.java

@@ -21,15 +21,19 @@ import junit.framework.AssertionFailedError;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.Test;
+
 import static org.junit.Assert.*;
 
 import java.io.IOException;
 import java.net.BindException;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
 import java.net.Socket;
 import java.net.ConnectException;
 import java.net.SocketException;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
+import java.util.Enumeration;
 
 import org.apache.hadoop.conf.Configuration;
 
@@ -99,6 +103,34 @@ public class TestNetUtils {
       fail("NetUtils.verifyHostnames threw unexpected UnknownHostException");
     }
   }
+  
+  /** 
+   * Test for {@link NetUtils#isLocalAddress(java.net.InetAddress)}
+   */
+  @Test
+  public void testIsLocalAddress() throws Exception {
+    // Test - local host is local address
+    assertTrue(NetUtils.isLocalAddress(InetAddress.getLocalHost()));
+    
+    // Test - all addresses bound network interface is local address
+    Enumeration<NetworkInterface> interfaces = NetworkInterface
+        .getNetworkInterfaces();
+    if (interfaces != null) { // Iterate through all network interfaces
+      while (interfaces.hasMoreElements()) {
+        NetworkInterface i = interfaces.nextElement();
+        Enumeration<InetAddress> addrs = i.getInetAddresses();
+        if (addrs == null) {
+          continue;
+        }
+        // Iterate through all the addresses of a network interface
+        while (addrs.hasMoreElements()) {
+          InetAddress addr = addrs.nextElement();
+          assertTrue(NetUtils.isLocalAddress(addr));
+        }
+      }
+    }
+    assertFalse(NetUtils.isLocalAddress(InetAddress.getByName("8.8.8.8")));
+  }
 
   @Test
   public void testWrapConnectException() throws Throwable {