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.shared.ldap.schema.syntaxes;
021
022 import org.apache.directory.shared.ldap.constants.SchemaConstants;
023 import org.apache.directory.shared.ldap.schema.AbstractSyntaxChecker;
024
025
026 /**
027 * A SyntaxChecker which verifies that a value is a Jpeg according to RFC 4517.
028 *
029 * The JFIF (Jpeg File Interchange Format) specify that a jpeg image starts with
030 * the following bytes :
031 * 0xFF 0xD8 (SOI, Start Of Image)
032 * 0xFF 0xE0 (App0)
033 * 0xNN 0xNN (Header length)
034 * "JFIF\0" (JFIF string with an ending \0)
035 * some other bytes which are related to the image.
036 *
037 * We will check for those 11 bytes, except the length.
038 *
039 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
040 * @version $Rev: 437007 $
041 */
042 public class JpegSyntaxChecker extends AbstractSyntaxChecker
043 {
044 /**
045 *
046 * Creates a new instance of JpegSyntaxChecker.
047 *
048 */
049 public JpegSyntaxChecker()
050 {
051 super( SchemaConstants.JPEG_SYNTAX );
052 }
053
054
055 /**
056 *
057 * Creates a new instance of JpegSyntaxChecker.
058 *
059 * @param oid the oid to associate with this new SyntaxChecker
060 *
061 */
062 protected JpegSyntaxChecker( String oid )
063 {
064 super( oid );
065 }
066
067 /* (non-Javadoc)
068 * @see org.apache.directory.shared.ldap.schema.SyntaxChecker#isValidSyntax(java.lang.Object)
069 */
070 public boolean isValidSyntax( Object value )
071 {
072 if ( value == null )
073 {
074 return false;
075 }
076
077 // The value must be a byte array
078 if ( ! ( value instanceof byte[] ) )
079 {
080 return false;
081 }
082
083 byte[] bytes = (byte[])value;
084
085 // The header must be at least 11 bytes long
086 if ( bytes.length < 11 )
087 {
088 return false;
089 }
090
091 if ( ( bytes[0] == (byte)0x00FF ) && // SOI
092 ( bytes[1] == (byte)0x00D8 ) &&
093 ( bytes[2] == (byte)0x00FF ) && // APP0
094 ( bytes[3] == (byte)0x00E0 ) &&
095 ( bytes[6] == 'J' ) && // JFIF
096 ( bytes[7] == 'F' ) && // JFIF
097 ( bytes[8] == 'I' ) && // JFIF
098 ( bytes[9] == 'F' ) &&
099 ( bytes[10] == 0x00 ) ) // \0
100 {
101 // Note : this is not because the header is correct
102 // that the file is a jpeg file. There are much more
103 // elements to check, but we are not writing a jpeg
104 // file checker...
105 return true;
106 }
107
108 return false;
109 }
110 }