/*
* 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.
*
*/
package org.apache.directory.server.dns.io.encoder;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
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:dev@directory.apache.org">Apache Directory Project</a>
*/
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() );
DEFAULT_ENCODERS = Collections.unmodifiableMap( map );
}
/**
* Encodes the {@link DnsMessage} into the {@link IoBuffer}.
*
* @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 );
}
}