HADOOP-17052. NetUtils.connect() throws unchecked exception (UnresolvedAddressException) causing clients to abort (#2036)

Contributed by Dhiraj Hegde.

Signed-off-by: Mingliang Liu <liuml07@apache.org>

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

@@ -37,6 +37,7 @@ import java.net.URISyntaxException;
 import java.net.UnknownHostException;
 import java.net.ConnectException;
 import java.nio.channels.SocketChannel;
+import java.nio.channels.UnresolvedAddressException;
 import java.util.Map.Entry;
 import java.util.regex.Pattern;
 import java.util.*;
@@ -534,6 +535,8 @@ public class NetUtils {
       }
     } catch (SocketTimeoutException ste) {
       throw new ConnectTimeoutException(ste.getMessage());
+    }  catch (UnresolvedAddressException uae) {
+      throw new UnknownHostException(uae.getMessage());
     }
 
     // There is a very rare case allowed by the TCP specification, such that

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

@@ -95,7 +95,25 @@ public class TestNetUtils {
       assertInException(se, "Invalid argument");
     }
   }
-  
+
+  @Test
+  public void testInvalidAddress() throws Throwable {
+    Configuration conf = new Configuration();
+
+    Socket socket = NetUtils.getDefaultSocketFactory(conf)
+        .createSocket();
+    socket.bind(new InetSocketAddress("127.0.0.1", 0));
+    try {
+      NetUtils.connect(socket,
+          new InetSocketAddress("invalid-test-host",
+              0), 20000);
+      socket.close();
+      fail("Should not have connected");
+    } catch (UnknownHostException uhe) {
+      LOG.info("Got exception: ", uhe);
+    }
+  }
+
   @Test
   public void testSocketReadTimeoutWithChannel() throws Exception {
     doSocketReadTimeoutTest(true);