org.owasp.esapi.codecs.UnixCodec Maven / Gradle / Ivy

/**
 * OWASP Enterprise Security API (ESAPI)
 * 
 * This file is part of the Open Web Application Security Project (OWASP)
 * Enterprise Security API (ESAPI) project. For details, please see
 * http://www.owasp.org/index.php/ESAPI.
 *
 * Copyright (c) 2007 - The OWASP Foundation
 * 
 * The ESAPI is published by OWASP under the BSD license. You should read and accept the
 * LICENSE before you use, modify, and/or redistribute this software.
 * 
 * @author Jeff Williams Aspect Security
 * @created 2007
 */
package org.owasp.esapi.codecs;


/**
 * Implementation of the Codec interface for '\' encoding from Unix command shell.
 * 
 * @author Jeff Williams (jeff.williams .at. aspectsecurity.com) Aspect Security
 * @since June 1, 2007
 * @see org.owasp.esapi.Encoder
 */
public class UnixCodec extends AbstractCharacterCodec {

	/**
	 * {@inheritDoc}
	 * 
	 * Returns backslash-encoded character
     *
     * @param immune
     */
	public String encodeCharacter( char[] immune, Character c ) {
		char ch = c.charValue();
		
		// check for immune characters
		if ( containsCharacter( ch, immune ) ) {
			return ""+ch;
		}
		
		// check for alphanumeric characters
		String hex = super.getHexForNonAlphanumeric( ch );
		if ( hex == null ) {
			return ""+ch;
		}
		
        return "\\" + c;
	}
	
	
	/**
	 * {@inheritDoc}
	 * 
	 * Returns the decoded version of the character starting at index, or
	 * null if no decoding is possible.
	 * 
	 * Formats all are legal both upper/lower case:
	 *   \x - all special characters
	 *   
	 */
	public Character decodeCharacter( PushbackSequence input ) {
		input.mark();
		Character first = input.next();
		if ( first == null ) {
			input.reset();
			return null;
		}
		
		// if this is not an encoded character, return null
		if ( first.charValue() != '\\' ) {
			input.reset();
			return null;
		}

		Character second = input.next();
		return second;
	}

}