From 6bf895b378b90027b14f751a03e3c8d100a575ab Mon Sep 17 00:00:00 2001
From: Aaron Myers <atm@apache.org>
Date: Thu, 17 Jan 2013 23:11:18 +0000
Subject: [PATCH] HDFS-4415. HostnameFilter should handle hostname resolution
 failures and continue processing. Contributed by Robert Kanter.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1434952 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop/lib/servlet/HostnameFilter.java    | 18 ++++++++++++-
 .../lib/servlet/TestHostnameFilter.java       | 26 +++++++++++++++++++
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  3 +++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/servlet/HostnameFilter.java b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/servlet/HostnameFilter.java
index 39b7e4fb61a..dd395f67495 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/servlet/HostnameFilter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/servlet/HostnameFilter.java
@@ -29,6 +29,9 @@ import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import java.io.IOException;
 import java.net.InetAddress;
+import java.net.UnknownHostException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Filter that resolves the requester hostname.
@@ -36,6 +39,7 @@ import java.net.InetAddress;
 @InterfaceAudience.Private
 public class HostnameFilter implements Filter {
   static final ThreadLocal<String> HOSTNAME_TL = new ThreadLocal<String>();
+  private static final Logger log = LoggerFactory.getLogger(HostnameFilter.class);
 
   /**
    * Initializes the filter.
@@ -66,7 +70,19 @@ public class HostnameFilter implements Filter {
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
     throws IOException, ServletException {
     try {
-      String hostname = InetAddress.getByName(request.getRemoteAddr()).getCanonicalHostName();
+      String hostname;
+      try {
+        String address = request.getRemoteAddr();
+        if (address != null) {
+          hostname = InetAddress.getByName(address).getCanonicalHostName();
+        } else {
+          log.warn("Request remote address is NULL");
+          hostname = "???";
+        }
+      } catch (UnknownHostException ex) {
+        log.warn("Request remote address could not be resolved, {0}", ex.toString(), ex);
+        hostname = "???";
+      }
       HOSTNAME_TL.set(hostname);
       chain.doFilter(request, response);
     } finally {
diff --git a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/lib/servlet/TestHostnameFilter.java b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/lib/servlet/TestHostnameFilter.java
index 44da0afd705..3148d3a6820 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/lib/servlet/TestHostnameFilter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-httpfs/src/test/java/org/apache/hadoop/lib/servlet/TestHostnameFilter.java
@@ -64,4 +64,30 @@ public class TestHostnameFilter extends HTestCase {
     filter.destroy();
   }
 
+  @Test
+  public void testMissingHostname() throws Exception {
+    ServletRequest request = Mockito.mock(ServletRequest.class);
+    Mockito.when(request.getRemoteAddr()).thenReturn(null);
+
+    ServletResponse response = Mockito.mock(ServletResponse.class);
+
+    final AtomicBoolean invoked = new AtomicBoolean();
+
+    FilterChain chain = new FilterChain() {
+      @Override
+      public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse)
+        throws IOException, ServletException {
+        assertTrue(HostnameFilter.get().contains("???"));
+        invoked.set(true);
+      }
+    };
+
+    Filter filter = new HostnameFilter();
+    filter.init(null);
+    assertNull(HostnameFilter.get());
+    filter.doFilter(request, response, chain);
+    assertTrue(invoked.get());
+    assertNull(HostnameFilter.get());
+    filter.destroy();
+  }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 58c88066334..546aaa01183 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -420,6 +420,9 @@ Release 2.0.3-alpha - Unreleased
 
     HDFS-1245. Pluggable block id generation. (shv)
 
+    HDFS-4415. HostnameFilter should handle hostname resolution failures and
+    continue processing. (Robert Kanter via atm)
+
   BREAKDOWN OF HDFS-3077 SUBTASKS
 
     HDFS-3077. Quorum-based protocol for reading and writing edit logs.