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.syntaxCheckers;
021
022 import org.apache.directory.shared.ldap.constants.SchemaConstants;
023 import org.apache.directory.shared.ldap.schema.SyntaxChecker;
024 import org.slf4j.Logger;
025 import org.slf4j.LoggerFactory;
026
027
028 /**
029 * A SyntaxChecker which verifies that a value is a Jpeg according to RFC 4517.
030 *
031 * The JFIF (Jpeg File Interchange Format) specify that a jpeg image starts with
032 * the following bytes :
033 * 0xFF 0xD8 (SOI, Start Of Image)
034 * 0xFF 0xE0 (App0)
035 * 0xNN 0xNN (Header length)
036 * "JFIF\0" (JFIF string with an ending \0)
037 * some other bytes which are related to the image.
038 *
039 * We will check for those 11 bytes, except the length.
040 *
041 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
042 * @version $Rev: 437007 $
043 */
044 public class JpegSyntaxChecker extends SyntaxChecker
045 {
046 /** A logger for this class */
047 private static final Logger LOG = LoggerFactory.getLogger( JpegSyntaxChecker.class );
048
049 /** The serialVersionUID */
050 private static final long serialVersionUID = 1L;
051
052 /**
053 * Creates a new instance of JpegSyntaxChecker.
054 */
055 public JpegSyntaxChecker()
056 {
057 super( SchemaConstants.JPEG_SYNTAX );
058 }
059
060
061 /**
062 * {@inheritDoc}
063 */
064 public boolean isValidSyntax( Object value )
065 {
066 if ( value == null )
067 {
068 LOG.debug( "Syntax invalid for '{}'", value );
069 return false;
070 }
071
072 // The value must be a byte array
073 if ( ! ( value instanceof byte[] ) )
074 {
075 LOG.debug( "Syntax invalid for '{}'", value );
076 return false;
077 }
078
079 byte[] bytes = (byte[])value;
080
081 // The header must be at least 11 bytes long
082 if ( bytes.length < 11 )
083 {
084 LOG.debug( "Syntax invalid for '{}'", value );
085 return false;
086 }
087
088 if ( ( bytes[0] == (byte)0x00FF ) && // SOI
089 ( bytes[1] == (byte)0x00D8 ) &&
090 ( bytes[2] == (byte)0x00FF ) && // APP0
091 ( bytes[3] == (byte)0x00E0 ) &&
092 ( bytes[6] == 'J' ) && // JFIF
093 ( bytes[7] == 'F' ) && // JFIF
094 ( bytes[8] == 'I' ) && // JFIF
095 ( bytes[9] == 'F' ) &&
096 ( bytes[10] == 0x00 ) ) // \0
097 {
098 // Note : this is not because the header is correct
099 // that the file is a jpeg file. There are much more
100 // elements to check, but we are not writing a jpeg
101 // file checker...
102 LOG.debug( "Syntax valid for '{}'", value );
103 return true;
104 }
105
106 LOG.debug( "Syntax invalid for '{}'", value );
107 return false;
108 }
109 }