Fix IllegalStateException in DnsClient when DNS server responds with DNAME record

src/main/java/io/vertx/core/dns/impl/DnsClientImpl.java

@@ -14,6 +14,7 @@
 import io.netty.channel.*;
 import io.netty.channel.socket.DatagramChannel;
 import io.netty.channel.socket.InternetProtocolFamily;
+import io.netty.handler.codec.DecoderException;
 import io.netty.handler.codec.dns.*;
 import io.netty.handler.logging.LoggingHandler;
 import io.netty.util.collection.LongObjectHashMap;
@@ -261,7 +262,14 @@ void handle(DnsResponse msg) {
         List<T> records = new ArrayList<>(count);
         for (int idx = 0;idx < count;idx++) {
           DnsRecord a = msg.recordAt(DnsSection.ANSWER, idx);
-          T record = RecordDecoder.decode(a);
+          T record;
+          try {
+            record = RecordDecoder.decode(a);
+          } catch (DecoderException e) {
+            fail(e);
+            return;
+          }
+
           if (isRequestedType(a.type(), types)) {
             records.add(record);
           }

src/main/java/io/vertx/core/dns/impl/decoder/RecordDecoder.java

@@ -222,7 +222,7 @@ public static <T> T decode(DnsRecord record) {
         DnsRecordType type = record.type();
         Function<DnsRecord, ?> decoder = decoders.get(type);
         if (decoder == null) {
-            throw new IllegalStateException("Unsupported resource record type [id: " + type + "].");
+            throw new DecoderException("DNS record decoding error occurred: Unsupported resource record type [id: " + type + "].");
         }
         T result = null;
         try {

src/test/java/io/vertx/core/dns/DNSTest.java

@@ -405,6 +405,19 @@ public void testLookup4CNAME() throws Exception {
     await();
   }
 
+  @Test
+  public void testResolveMXWhenDNSRepliesWithDNAMERecord() throws Exception {
+    final DnsClient dns = prepareDns();
+    dnsServer.testResolveDNAME("mail.vertx.io");
+
+    dns.resolveMX("vertx.io")
+      .onComplete(ar -> {
+        assertTrue(ar.failed());
+        testComplete();
+      });
+    await();
+  }
+
   private TestLoggerFactory testLogging(DnsClientOptions options) {
     final String ip = "10.0.0.1";
     dnsServer.testResolveA(ip);

src/test/java/io/vertx/test/fakedns/DnameRecordEncoder.java

@@ -0,0 +1,15 @@
+package io.vertx.test.fakedns;
+
+import org.apache.directory.server.dns.io.encoder.ResourceRecordEncoder;
+import org.apache.directory.server.dns.messages.ResourceRecord;
+import org.apache.directory.server.dns.store.DnsAttribute;
+import org.apache.mina.core.buffer.IoBuffer;
+
+public class DnameRecordEncoder extends ResourceRecordEncoder  {
+
+  protected void putResourceRecordData(IoBuffer byteBuffer, ResourceRecord record )
+  {
+    String domainName = record.get( DnsAttribute.DOMAIN_NAME );
+    putDomainName( byteBuffer, domainName );
+  }
+}

src/test/java/io/vertx/test/fakedns/DnsMessageEncoder.java

@@ -0,0 +1,233 @@
+package io.vertx.test.fakedns;
+
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ *
+ */
+
+
+  import java.io.IOException;
+  import java.util.*;
+
+  import org.apache.directory.server.dns.io.encoder.*;
+  import org.apache.directory.server.dns.messages.DnsMessage;
+  import org.apache.directory.server.dns.messages.MessageType;
+  import org.apache.directory.server.dns.messages.OpCode;
+  import org.apache.directory.server.dns.messages.QuestionRecord;
+  import org.apache.directory.server.dns.messages.RecordType;
+  import org.apache.directory.server.dns.messages.ResourceRecord;
+  import org.apache.directory.server.dns.messages.ResponseCode;
+  import org.apache.directory.server.i18n.I18n;
+  import org.apache.mina.core.buffer.IoBuffer;
+  import org.slf4j.Logger;
+  import org.slf4j.LoggerFactory;
+
+
+/**
+ * An encoder for DNS messages.  The primary usage of the DnsMessageEncoder is
+ * to call the <code>encode(ByteBuffer, DnsMessage)</code> method which will
+ * write the message to the outgoing ByteBuffer according to the DnsMessage
+ * encoding in RFC-1035.
+ *
+ * @author <a href="mailto:[email protected]">Apache Directory Project</a>
+ * @version $Rev$, $Date$
+ */
+public class DnsMessageEncoder
+{
+  /** the log for this class */
+  private static final Logger log = LoggerFactory.getLogger( DnsMessageEncoder.class );
+
+  /**
+   * A Hashed Adapter mapping record types to their encoders.
+   */
+  private static final Map<RecordType, RecordEncoder> DEFAULT_ENCODERS;
+
+  static
+  {
+    Map<RecordType, RecordEncoder> map = new HashMap<RecordType, RecordEncoder>();
+
+    map.put( RecordType.SOA, new StartOfAuthorityRecordEncoder() );
+    map.put( RecordType.A, new AddressRecordEncoder() );
+    map.put( RecordType.NS, new NameServerRecordEncoder() );
+    map.put( RecordType.CNAME, new CanonicalNameRecordEncoder() );
+    map.put( RecordType.PTR, new PointerRecordEncoder() );
+    map.put( RecordType.MX, new MailExchangeRecordEncoder() );
+    map.put( RecordType.SRV, new ServerSelectionRecordEncoder() );
+    map.put( RecordType.TXT, new TextRecordEncoder() );
+    map.put( RecordType.DNAME,  new DnameRecordEncoder());
+
+    DEFAULT_ENCODERS = Collections.unmodifiableMap( map );
+  }
+
+
+  /**
+   * Encodes the {@link DnsMessage} into the {@link ByteBuffer}.
+   *
+   * @param byteBuffer
+   * @param message
+   */
+  public void encode( IoBuffer byteBuffer, DnsMessage message )
+  {
+    byteBuffer.putShort( ( short ) message.getTransactionId() );
+
+    byte header = ( byte ) 0x00;
+    header |= encodeMessageType( message.getMessageType() );
+    header |= encodeOpCode( message.getOpCode() );
+    header |= encodeAuthoritativeAnswer( message.isAuthoritativeAnswer() );
+    header |= encodeTruncated( message.isTruncated() );
+    header |= encodeRecursionDesired( message.isRecursionDesired() );
+    byteBuffer.put( header );
+
+    header = ( byte ) 0x00;
+    header |= encodeRecursionAvailable( message.isRecursionAvailable() );
+    header |= encodeResponseCode( message.getResponseCode() );
+    byteBuffer.put( header );
+
+    byteBuffer
+      .putShort( ( short ) ( message.getQuestionRecords() != null ? message.getQuestionRecords().size() : 0 ) );
+    byteBuffer.putShort( ( short ) ( message.getAnswerRecords() != null ? message.getAnswerRecords().size() : 0 ) );
+    byteBuffer.putShort( ( short ) ( message.getAuthorityRecords() != null ? message.getAuthorityRecords().size()
+      : 0 ) );
+    byteBuffer.putShort( ( short ) ( message.getAdditionalRecords() != null ? message.getAdditionalRecords().size()
+      : 0 ) );
+
+    putQuestionRecords( byteBuffer, message.getQuestionRecords() );
+    putResourceRecords( byteBuffer, message.getAnswerRecords() );
+    putResourceRecords( byteBuffer, message.getAuthorityRecords() );
+    putResourceRecords( byteBuffer, message.getAdditionalRecords() );
+  }
+
+
+  private void putQuestionRecords( IoBuffer byteBuffer, List<QuestionRecord> questions )
+  {
+    if ( questions == null )
+    {
+      return;
+    }
+
+    QuestionRecordEncoder encoder = new QuestionRecordEncoder();
+
+    Iterator<QuestionRecord> it = questions.iterator();
+
+    while ( it.hasNext() )
+    {
+      QuestionRecord question = it.next();
+      encoder.put( byteBuffer, question );
+    }
+  }
+
+
+  private void putResourceRecords( IoBuffer byteBuffer, List<ResourceRecord> records )
+  {
+    if ( records == null )
+    {
+      return;
+    }
+
+    Iterator<ResourceRecord> it = records.iterator();
+
+    while ( it.hasNext() )
+    {
+      ResourceRecord record = it.next();
+
+      try
+      {
+        put( byteBuffer, record );
+      }
+      catch ( IOException ioe )
+      {
+        log.error( ioe.getLocalizedMessage(), ioe );
+      }
+    }
+  }
+
+
+  private void put( IoBuffer byteBuffer, ResourceRecord record ) throws IOException
+  {
+    RecordType type = record.getRecordType();
+
+    RecordEncoder encoder = DEFAULT_ENCODERS.get( type );
+
+    if ( encoder == null )
+    {
+      throw new IOException( I18n.err( I18n.ERR_597, type ) );
+    }
+
+    encoder.put( byteBuffer, record );
+  }
+
+
+  private byte encodeMessageType( MessageType messageType )
+  {
+    byte oneBit = ( byte ) ( messageType.convert() & 0x01 );
+    return ( byte ) ( oneBit << 7 );
+  }
+
+
+  private byte encodeOpCode( OpCode opCode )
+  {
+    byte fourBits = ( byte ) ( opCode.convert() & 0x0F );
+    return ( byte ) ( fourBits << 3 );
+  }
+
+
+  private byte encodeAuthoritativeAnswer( boolean authoritative )
+  {
+    if ( authoritative )
+    {
+      return ( byte ) ( ( byte ) 0x01 << 2 );
+    }
+    return ( byte ) 0;
+  }
+
+
+  private byte encodeTruncated( boolean truncated )
+  {
+    if ( truncated )
+    {
+      return ( byte ) ( ( byte ) 0x01 << 1 );
+    }
+    return 0;
+  }
+
+
+  private byte encodeRecursionDesired( boolean recursionDesired )
+  {
+    if ( recursionDesired )
+    {
+      return ( byte ) 0x01;
+    }
+    return 0;
+  }
+
+
+  private byte encodeRecursionAvailable( boolean recursionAvailable )
+  {
+    if ( recursionAvailable )
+    {
+      return ( byte ) ( ( byte ) 0x01 << 7 );
+    }
+    return 0;
+  }
+
+
+  private byte encodeResponseCode( ResponseCode responseCode )
+  {
+    return ( byte ) ( responseCode.convert() & 0x0F );
+  }
+}

src/test/java/io/vertx/test/fakedns/FakeDNSServer.java

@@ -13,7 +13,6 @@
 
 import org.apache.directory.server.dns.DnsException;
 import org.apache.directory.server.dns.DnsServer;
-import org.apache.directory.server.dns.io.encoder.DnsMessageEncoder;
 import org.apache.directory.server.dns.io.encoder.ResourceRecordEncoder;
 import org.apache.directory.server.dns.messages.DnsMessage;
 import org.apache.directory.server.dns.messages.DnsMessageModifier;
@@ -263,6 +262,24 @@ public Set<ResourceRecord> getRecords(QuestionRecord questionRecord) throws org.
     });
   }
 
+  public FakeDNSServer testResolveDNAME(final String dname) {
+    return store(new RecordStore() {
+      @Override
+      public Set<ResourceRecord> getRecords(QuestionRecord questionRecord) throws org.apache.directory.server.dns.DnsException {
+        Set<ResourceRecord> set = new HashSet<>();
+
+        ResourceRecordModifier rm = new ResourceRecordModifier();
+        rm.setDnsClass(RecordClass.IN);
+        rm.setDnsName("dns.vertx.io");
+        rm.setDnsTtl(100);
+        rm.setDnsType(RecordType.DNAME);
+        rm.put(DnsAttribute.DOMAIN_NAME, dname);
+        set.add(rm.getEntry());
+        return set;
+      }
+    });
+  }
+
   public FakeDNSServer testLookup4(final String ip) {
     return store(new RecordStore() {
       @Override