8075378: JNDI DnsClient Exception Handling

Reviewed-by: vinnie

src/share/classes/com/sun/jndi/dns/DnsClient.java

 /*
- * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -184,6 +184,7 @@ public class DnsClient {
         Exception caughtException = null;
         boolean[] doNotRetry = new boolean[servers.length];
 
+        try {
             //
             // The UDP retry strategy is to try the 1st server, and then
             // each server in order. If no answer, double the timeout
@@ -282,6 +283,7 @@ public class DnsClient {
                             doNotRetry[i] = true;
                         }
                     } catch (NameNotFoundException e) {
+                        // This is authoritative, so return immediately
                         throw e;
                     } catch (CommunicationException e) {
                         if (caughtException == null) {
@@ -296,7 +298,10 @@ public class DnsClient {
                 } // servers
             } // retries
 
-        reqs.remove(xid);
+        } finally {
+            reqs.remove(xid); // cleanup
+        }
+
         if (caughtException instanceof NamingException) {
             throw (NamingException) caughtException;
         }