Backport UnknownHostException mentions hostname with search domain added, close AsyncHttpClient#1223

Author: slandelle

netty-bp/resolver-dns/src/main/java/io/netty/resolver/dns/DnsNameResolverContext.java

@@ -70,6 +70,7 @@ public void operationComplete(Future<AddressedEnvelope<DnsResponse, InetSocketAd
     private final DnsNameResolver parent;
     private final DnsServerAddressStream nameServerAddrs;
     private final String hostname;
+    protected String pristineHostname;
     private final DnsCache resolveCache;
     private final boolean traceEnabled;
     private final int maxAllowedQueries;
@@ -117,6 +118,7 @@ public void operationComplete(Future<T> future) throws Exception {
                         String nextHostname = DnsNameResolverContext.this.hostname + "." + searchDomain;
                         DnsNameResolverContext<T> nextContext = newResolverContext(parent,
                             nextHostname, resolveCache);
+                        nextContext.pristineHostname = hostname;
                         nextContext.internalResolve(nextPromise);
                         nextPromise.addListener(this);
                     } else {
@@ -450,8 +452,13 @@ private void finishResolve(Promise<T> promise) {
         final int tries = maxAllowedQueries - allowedQueries;
         final StringBuilder buf = new StringBuilder(64);
 
-        buf.append("failed to resolve '")
-           .append(hostname).append('\'');
+        buf.append("failed to resolve '");
+        if (pristineHostname != null) {
+          buf.append(pristineHostname);
+        } else {
+          buf.append(hostname);
+        }
+        buf.append('\'');
         if (tries > 1) {
             if (tries < maxAllowedQueries) {
                 buf.append(" after ")

netty-bp/resolver-dns/src/test/java/io/netty/resolver/dns/SearchDomainTest.java

@@ -24,6 +24,7 @@
 import org.junit.Test;
 
 import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -34,7 +35,10 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.hamcrest.Matchers.not;
+import static org.hamcrest.core.StringContains.containsString;
 
 public class SearchDomainTest {
 
@@ -265,4 +269,23 @@ private List<String> assertResolveAll(DnsNameResolver resolver, String inetHost)
         }
         return list;
     }
+
+    @Test
+    public void testExceptionMsgNoSearchDomain() throws Exception {
+        Set<String> domains = new HashSet<String>();
+
+        TestDnsServer.MapRecordStoreA store = new TestDnsServer.MapRecordStoreA(domains);
+        dnsServer = new TestDnsServer(store);
+        dnsServer.start();
+
+        resolver = newResolver().searchDomains(Collections.singletonList("foo.com")).build();
+
+        Future<InetAddress> fut = resolver.resolve("unknown.hostname");
+        assertTrue(fut.await(10, TimeUnit.SECONDS));
+        assertFalse(fut.isSuccess());
+        final Throwable cause = fut.cause();
+        assertEquals(UnknownHostException.class, cause.getClass());
+        assertThat("search domain is included in UnknownHostException", cause.getMessage(),
+            not(containsString("foo.com")));
+    }
 }