From 2c841e65648244d46f98e988cdb964f7d5681775 Mon Sep 17 00:00:00 2001
From: rohithsharmaks <rohithsharmaks@apache.org>
Date: Thu, 7 Jan 2016 10:42:48 +0530
Subject: [PATCH] HADOOP-12687. SecureUtil#QualifiedHostResolver#getByName
 should also try to resolve direct hostname (Sunil G via rohithsharmaks)

(cherry picked from commit 2b252844e04eebd4f32815d4bd6f914c02994709)
---
 hadoop-common-project/hadoop-common/CHANGES.txt             | 4 ++++
 .../main/java/org/apache/hadoop/security/SecurityUtil.java  | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 1d612862b07..44f561ab60b 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -19,6 +19,10 @@ Release 2.9.0 - UNRELEASED
 
   BUG FIXES
 
+    HADOOP-12687. SecureUtil#QualifiedHostResolver#getByName should also try to
+    resolve direct hostname, incase multiple loopback addresses are present in
+    /etc/hosts (Sunil G via rohithsharmaks)
+
 Release 2.8.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
index 38096ab4715..714c923a627 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
@@ -580,7 +580,13 @@ public class SecurityUtil {
           addr = getByNameWithSearch(host);
           if (addr == null) {
             addr = getByExactName(host);
+            // If multiple loopback addresses are present, a direct lookup
+            // will be helpful
+            if (addr == null) {
+              addr = InetAddress.getByName(host);
+            }
           }
+
         }
       }
       // unresolvable!