HADOOP-8238. NetUtils#getHostNameOfIP blows up if given ip:port string w/o port. Contributed by Eli Collins

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1308192 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -302,6 +302,9 @@ Release 2.0.0 - UNRELEASED
     HADOOP-8218. RPC.closeProxy shouldn't throw error when closing a mock
     (todd)
 
+    HADOOP-8238. NetUtils#getHostNameOfIP blows up if given ip:port
+    string w/o port. (eli)
+
   BREAKDOWN OF HADOOP-7454 SUBTASKS
 
     HADOOP-7455. HA: Introduce HA Service Protocol Interface. (suresh)

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

@@ -570,31 +570,29 @@ public class NetUtils {
     }
   }
 
-  private static final Pattern ipPattern = // Pattern for matching hostname to ip:port
-    Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}:?\\d*");
+  private static final Pattern ipPortPattern = // Pattern for matching ip[:port]
+    Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}(:\\d+)?");
   
   /**
-   * Attempt to obtain the host name of a name specified by ip address.  
-   * Check that the node name is an ip addr and if so, attempt to determine
-   * its host name.  If the name is not an IP addr, or the actual name cannot
-   * be determined, return null.
+   * Attempt to obtain the host name of the given string which contains
+   * an IP address and an optional port.
    * 
-   * @return Host name or null
+   * @param ipPort string of form ip[:port]
+   * @return Host name or null if the name can not be determined
    */
-  public static String getHostNameOfIP(String ip) {
-    // If name is not an ip addr, don't bother looking it up
-    if(!ipPattern.matcher(ip).matches())
+  public static String getHostNameOfIP(String ipPort) {
+    if (null == ipPort || !ipPortPattern.matcher(ipPort).matches()) {
       return null;
+    }
     
-    String hostname = "";
     try {
-      String n = ip.substring(0, ip.indexOf(':'));
-      hostname = InetAddress.getByName(n).getHostName();
+      int colonIdx = ipPort.indexOf(':');
+      String ip = (-1 == colonIdx) ? ipPort
+          : ipPort.substring(0, ipPort.indexOf(':'));
+      return InetAddress.getByName(ip).getHostName();
     } catch (UnknownHostException e) {
       return null;
     }
-    
-    return hostname; 
   }
 
   /**

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

@@ -499,6 +499,18 @@ public class TestNetUtils {
     assertEquals("scheme://host.a.b/path", uri.toString());
   }
   
+  @Test
+  public void testGetHostNameOfIP() {
+    assertNull(NetUtils.getHostNameOfIP(null));
+    assertNull(NetUtils.getHostNameOfIP(""));
+    assertNull(NetUtils.getHostNameOfIP("crazytown"));
+    assertNull(NetUtils.getHostNameOfIP("127.0.0.1:"));   // no port
+    assertNull(NetUtils.getHostNameOfIP("127.0.0.1:-1")); // bogus port
+    assertNull(NetUtils.getHostNameOfIP("127.0.0.1:A"));  // bogus port
+    assertNotNull(NetUtils.getHostNameOfIP("127.0.0.1"));
+    assertNotNull(NetUtils.getHostNameOfIP("127.0.0.1:1"));
+  }
+
   private <T> void assertBetterArrayEquals(T[] expect, T[]got) {
     String expectStr = StringUtils.join(expect, ", ");
     String gotStr = StringUtils.join(got, ", ");