1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20
21 package org.apache.directory.server.dns.protocol;
22
23
24 import org.apache.directory.server.dns.io.decoder.DnsMessageDecoder;
25 import org.apache.mina.common.BufferDataException;
26 import org.apache.mina.common.ByteBuffer;
27 import org.apache.mina.common.IoSession;
28 import org.apache.mina.filter.codec.CumulativeProtocolDecoder;
29 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
30
31
32 /**
33 * A {@link CumulativeProtocolDecoder} which supports DNS operation over TCP,
34 * by reassembling split packets prior to decoding.
35 *
36 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
37 * @version $Rev: 545041 $, $Date: 2007-06-06 20:31:34 -0700 (Wed, 06 Jun 2007) $
38 */
39 public class DnsTcpDecoder extends CumulativeProtocolDecoder
40 {
41 private DnsMessageDecoder decoder = new DnsMessageDecoder();
42
43 private int maxObjectSize = 16384; // 16KB
44
45
46 /**
47 * Returns the allowed maximum size of the object to be decoded.
48 * If the size of the object to be decoded exceeds this value, this
49 * decoder will throw a {@link BufferDataException}. The default
50 * value is <tt>16384</tt> (16KB).
51 *
52 * @return The max object size.
53 */
54 public int getMaxObjectSize()
55 {
56 return maxObjectSize;
57 }
58
59
60 /**
61 * Sets the allowed maximum size of the object to be decoded.
62 * If the size of the object to be decoded exceeds this value, this
63 * decoder will throw a {@link BufferDataException}. The default
64 * value is <tt>16384</tt> (16KB).
65 *
66 * @param maxObjectSize
67 */
68 public void setMaxObjectSize( int maxObjectSize )
69 {
70 if ( maxObjectSize <= 0 )
71 {
72 throw new IllegalArgumentException( "maxObjectSize: " + maxObjectSize );
73 }
74
75 this.maxObjectSize = maxObjectSize;
76 }
77
78
79 @Override
80 protected boolean doDecode( IoSession session, ByteBuffer in, ProtocolDecoderOutput out ) throws Exception
81 {
82 if ( !in.prefixedDataAvailable( 2, maxObjectSize ) )
83 {
84 return false;
85 }
86
87 in.getShort();
88
89 out.write( decoder.decode( in ) );
90
91 return true;
92 }
93 }