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 package org.apache.directory.server.kerberos.shared.messages.value;
021
022
023 import java.nio.BufferOverflowException;
024 import java.nio.ByteBuffer;
025 import java.util.Arrays;
026
027 import org.apache.directory.server.kerberos.shared.crypto.checksum.ChecksumType;
028 import org.apache.directory.shared.asn1.AbstractAsn1Object;
029 import org.apache.directory.shared.asn1.ber.tlv.TLV;
030 import org.apache.directory.shared.asn1.ber.tlv.UniversalTag;
031 import org.apache.directory.shared.asn1.ber.tlv.Value;
032 import org.apache.directory.shared.asn1.codec.EncoderException;
033 import org.apache.directory.shared.ldap.util.StringTools;
034 import org.slf4j.Logger;
035 import org.slf4j.LoggerFactory;
036
037
038 /**
039 * The Checksum structure is used to store a checksum associated to a type.
040 *
041 * The ASN.1 grammar is :
042 * Checksum ::= SEQUENCE {
043 * cksumtype [0] Int32,
044 * checksum [1] OCTET STRING
045 * }
046 *
047 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
048 * @version $Rev: 642496 $, $Date: 2008-03-29 05:09:22 +0200 (Sat, 29 Mar 2008) $
049 */
050 public class Checksum extends AbstractAsn1Object
051 {
052 /** The logger */
053 private static final Logger log = LoggerFactory.getLogger( Checksum.class );
054
055 /** Speedup for logs */
056 private static final boolean IS_DEBUG = log.isDebugEnabled();
057
058 /** The checksum type used */
059 private ChecksumType cksumtype;
060
061 /** The byte array containing the checksum */
062 private byte[] checksum;
063
064 // Storage for computed lengths
065 private transient int checksumTypeLength;
066 private transient int checksumBytesLength;
067 private transient int checksumLength;
068
069
070 /**
071 * Creates a new instance of Checksum.
072 */
073 public Checksum()
074 {
075 }
076
077
078 /**
079 * Creates a new instance of Checksum.
080 *
081 * @param cksumtype The checksum type used
082 * @param checksum The checksum value
083 */
084 public Checksum( ChecksumType cksumtype, byte[] checksum )
085 {
086 this.cksumtype = cksumtype;
087 this.checksum = checksum;
088 }
089
090
091 /**
092 * @see Object#equals(Object)
093 */
094 public boolean equals( Object o )
095 {
096 if ( this == o )
097 {
098 return true;
099 }
100
101 if ( !( o instanceof Checksum ) )
102 {
103 return false;
104 }
105
106 Checksum that = ( Checksum ) o;
107
108 return ( cksumtype == that.cksumtype ) && ( Arrays.equals( checksum, that.checksum ) );
109 }
110
111
112 /**
113 * Returns the checksum value.
114 *
115 * @return The checksum value.
116 */
117 public byte[] getChecksumValue()
118 {
119 return checksum;
120 }
121
122
123 /**
124 * Set the checksum Value.
125 *
126 * @param checksum The checksum value
127 */
128 public void setChecksumValue( byte[] checksum )
129 {
130 this.checksum = checksum;
131 }
132
133
134 /**
135 * Returns the {@link ChecksumType}.
136 *
137 * @return The {@link ChecksumType}.
138 */
139 public ChecksumType getChecksumType()
140 {
141 return cksumtype;
142 }
143
144
145 /**
146 * Set the {@link ChecksumType}.
147 *
148 * @param cksumType The checksum algorithm used
149 */
150 public void setChecksumType( ChecksumType cksumType )
151 {
152 this.cksumtype = cksumType;
153 }
154
155
156 /**
157 * Compute the checksum length
158 *
159 * Checksum :
160 *
161 * 0x30 L1 checksum sequence
162 * |
163 * +--> 0xA0 L2 cksumtype tag
164 * | |
165 * | +--> 0x02 L2-1 cksumtype (int)
166 * |
167 * +--> 0xA1 L3 checksum tag
168 * |
169 * +--> 0x04 L3-1 checksum (OCTET STRING)
170 *
171 * where L1 = L2 + lenght(0xA0) + length(L2) +
172 * L3 + lenght(0xA1) + length(L3)
173 * and
174 * L2 = L2-1 + length(0x02) + length( L2-1)
175 * L3 = L3-1 + length(0x04) + length( L3-1)
176 */
177 public int computeLength()
178 {
179 // Compute the checksulType. The Length will always be contained in 1 byte
180 checksumTypeLength = 1 + 1 + Value.getNbBytes( cksumtype.getOrdinal() );
181 checksumLength = 1 + TLV.getNbBytes( checksumTypeLength ) + checksumTypeLength;
182
183 // Compute the checksum Value
184 if ( checksum == null )
185 {
186 checksumBytesLength = 1 + 1;
187 }
188 else
189 {
190 checksumBytesLength = 1 + TLV.getNbBytes( checksum.length ) + checksum.length;
191 }
192
193 checksumLength += 1 + TLV.getNbBytes( checksumBytesLength ) + checksumBytesLength;
194
195 // Compute the whole sequence length
196 int checksumSeqLength = 1 + Value.getNbBytes( checksumLength ) + checksumLength;
197
198 return checksumSeqLength;
199
200 }
201
202
203 /**
204 * Encode the Checksum message to a PDU.
205 *
206 * Checksum :
207 *
208 * 0x30 LL
209 * 0xA0 LL
210 * 0x02 0x01 cksumtype
211 * 0xA1 LL
212 * 0x04 LL Checksum
213 *
214 * @param buffer The buffer where to put the PDU. It should have been allocated
215 * before, with the right size.
216 * @return The constructed PDU.
217 */
218 public ByteBuffer encode( ByteBuffer buffer ) throws EncoderException
219 {
220 if ( buffer == null )
221 {
222 throw new EncoderException( "Cannot put a PDU in a null buffer !" );
223 }
224
225 try
226 {
227 // The Checksum SEQ Tag
228 buffer.put( UniversalTag.SEQUENCE_TAG );
229 buffer.put( TLV.getBytes( checksumLength ) );
230
231 // The cksumtype, first the tag, then the value
232 buffer.put( ( byte ) 0xA0 );
233 buffer.put( TLV.getBytes( checksumTypeLength ) );
234 Value.encode( buffer, cksumtype.getOrdinal() );
235
236 // The checksum, first the tag, then the value
237 buffer.put( ( byte ) 0xA1 );
238 buffer.put( TLV.getBytes( checksumBytesLength ) );
239 Value.encode( buffer, checksum );
240 }
241 catch ( BufferOverflowException boe )
242 {
243 log.error( "Cannot encode the Checksum object, the PDU size is {} when only {} bytes has been allocated", 1
244 + TLV.getNbBytes( checksumLength ) + checksumLength, buffer.capacity() );
245 throw new EncoderException( "The PDU buffer size is too small !" );
246 }
247
248 if ( IS_DEBUG )
249 {
250 log.debug( "Checksum encoding : {}", StringTools.dumpBytes( buffer.array() ) );
251 log.debug( "Checksum initial value : {}", toString() );
252 }
253
254 return buffer;
255 }
256
257 /**
258 * @see Object#toString()
259 */
260 public String toString()
261 {
262 return toString( "" );
263 }
264
265
266 /**
267 * @see Object#toString()
268 */
269 public String toString( String tabs )
270 {
271 StringBuilder sb = new StringBuilder();
272
273 sb.append( tabs ).append( "Checksum : {\n" );
274 sb.append( tabs ).append( " cksumtype: " ).append( cksumtype ).append( '\n' );
275
276 if ( checksum != null )
277 {
278 sb.append( tabs + " checksum:" ).append( StringTools.dumpBytes( checksum ) ).append( '\n' );
279 }
280
281 sb.append( tabs + "}\n" );
282
283 return sb.toString();
284 }
285 }