001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 *
019 */
020
021 package org.apache.directory.server.dns.protocol;
022
023
024 import org.apache.directory.server.dns.io.encoder.DnsMessageEncoder;
025 import org.apache.directory.server.dns.messages.DnsMessage;
026 import org.apache.mina.core.buffer.IoBuffer;
027 import org.apache.mina.core.session.IoSession;
028 import org.apache.mina.filter.codec.ProtocolEncoderAdapter;
029 import org.apache.mina.filter.codec.ProtocolEncoderOutput;
030
031
032 /**
033 * A ProtocolEncoder for use in the MINA framework that uses the
034 * DnsMessageEncoder to encode DnsMessages.
035 *
036 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
037 * @version $Rev: 545041 $, $Date: 2007-06-06 20:31:34 -0700 (Wed, 06 Jun 2007) $
038 */
039 public class DnsTcpEncoder extends ProtocolEncoderAdapter
040 {
041 private DnsMessageEncoder encoder = new DnsMessageEncoder();
042
043
044 public void encode( IoSession session, Object message, ProtocolEncoderOutput out )
045 {
046 IoBuffer buf = IoBuffer.allocate( 1024 );
047
048 // make space for short length
049 buf.putShort( ( short ) 0 );
050
051 encoder.encode( buf, ( DnsMessage ) message );
052
053 // mark position
054 int end = buf.position();
055
056 // length is the data minus 2 bytes for the pre-pended length
057 short recordLength = ( short ) ( end - 2 );
058
059 // write the length
060 buf.rewind();
061 buf.putShort( recordLength );
062
063 // set the position back before flipping the buffer
064 buf.position( end );
065 buf.flip();
066
067 out.write( buf );
068 }
069 }