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 021package org.apache.directory.server.dns.protocol; 022 023 024import org.apache.directory.server.dns.io.decoder.DnsMessageDecoder; 025import org.apache.directory.server.i18n.I18n; 026import org.apache.mina.core.buffer.IoBuffer; 027import org.apache.mina.core.session.IoSession; 028import org.apache.mina.filter.codec.CumulativeProtocolDecoder; 029import org.apache.mina.filter.codec.ProtocolDecoderOutput; 030 031 032/** 033 * A {@link CumulativeProtocolDecoder} which supports DNS operation over TCP, 034 * by reassembling split packets prior to decoding. 035 * 036 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 037 */ 038public class DnsTcpDecoder extends CumulativeProtocolDecoder 039{ 040 private DnsMessageDecoder decoder = new DnsMessageDecoder(); 041 042 private int maxObjectSize = 16384; // 16KB 043 044 045 /** 046 * Returns the allowed maximum size of the object to be decoded. 047 * 048 * @return The max object size. 049 */ 050 public int getMaxObjectSize() 051 { 052 return maxObjectSize; 053 } 054 055 056 /** 057 * Sets the allowed maximum size of the object to be decoded. 058 * If the size of the object to be decoded exceeds this value, this 059 * decoder will throw a {@link IllegalArgumentException}. The default 060 * value is <tt>16384</tt> (16KB). 061 * 062 * @param maxObjectSize 063 */ 064 public void setMaxObjectSize( int maxObjectSize ) 065 { 066 if ( maxObjectSize <= 0 ) 067 { 068 throw new IllegalArgumentException( I18n.err( I18n.ERR_634, maxObjectSize ) ); 069 } 070 071 this.maxObjectSize = maxObjectSize; 072 } 073 074 075 @Override 076 protected boolean doDecode( IoSession session, IoBuffer in, ProtocolDecoderOutput out ) throws Exception 077 { 078 if ( !in.prefixedDataAvailable( 2, maxObjectSize ) ) 079 { 080 return false; 081 } 082 083 in.getShort(); 084 085 out.write( decoder.decode( in ) ); 086 087 return true; 088 } 089}