HDFS-6008. Merging change r1571881 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1571883 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -292,6 +292,9 @@ Release 2.4.0 - UNRELEASED
 
     HDFS-5922. DN heartbeat thread can get stuck in tight loop. (Arpit Agarwal)
 
+    HDFS-6008. Namenode dead node link is giving HTTP error 500.
+    (Benoy Antony via cnauroth)
+
 Release 2.3.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/JspHelper.java

@@ -147,7 +147,9 @@ public class JspHelper {
    */
   public static final class Url {
     public static String authority(String scheme, DatanodeID d) {
-      String fqdn = canonicalize(d.getIpAddr());
+      String fqdn = (d.getIpAddr() != null && !d.getIpAddr().isEmpty())?
+          canonicalize(d.getIpAddr()): 
+          d.getHostName();
       if (scheme.equals("http")) {
         return fqdn + ":" + d.getInfoPort();
       } else if (scheme.equals("https")) {

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/common/TestJspHelper.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.server.common;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.*;
 
@@ -611,5 +612,20 @@ public class TestJspHelper {
     assertTrue(upgradeStatusReport.getStatusText(true).equals(
         MessageFormat.format(EXPECTED_NOTF_PATTERN, version)));
   }  
+  
+  @Test 
+  public void testAuthority(){
+    DatanodeID dnWithIp = new DatanodeID("127.0.0.1", "hostName", null,
+        50020, 50075, 50076, 50010);
+    assertNotNull(JspHelper.Url.authority("http", dnWithIp));
+
+    DatanodeID dnWithNullIp = new DatanodeID(null, "hostName", null,
+        50020, 50075, 50076, 50010);
+    assertNotNull(JspHelper.Url.authority("http", dnWithNullIp));
+
+    DatanodeID dnWithEmptyIp = new DatanodeID("", "hostName", null,
+        50020, 50075, 50076, 50010);
+    assertNotNull(JspHelper.Url.authority("http", dnWithEmptyIp));
+  }
 }