/*
 * $Header: /home/cvs/jakarta-tomcat/src/share/org/apache/tomcat/util/HexUtils.java,v 1.4 2000/02/14 04:59:42 costin Exp $
 * $Revision: 1.4 $
 * $Date: 2000/02/14 04:59:42 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */ 


package org.apache.tomcat.util;

import java.io.ByteArrayOutputStream;

/**
 * Library of utility methods useful in dealing with converting byte arrays
 * to and from strings of hexadecimal digits.
 *
 * @author Craig R. McClanahan
 */

public final class HexUtils {
    // Code from Ajp11, from Apache's JServ
    
    // Table for HEX to DEC byte translation
    public static final int[] DEC = {
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        00, 01, 02, 03, 04, 05, 06, 07,  8,  9, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    };
    


    /**
     * The string manager for this package.
     */
    private static StringManager sm =
	StringManager.getManager("org.apache.tomcat.util");


    /**
     * Convert a String of hexadecimal digits into the corresponding
     * byte array by encoding each two hexadecimal digits as a byte.
     *
     * @param digits Hexadecimal digits representation
     *
     * @exception IllegalArgumentException if an invalid hexadecimal digit
     *  is found, or the input string contains an odd number of hexadecimal
     *  digits
     */
    public static byte[] convert(String digits) {

	ByteArrayOutputStream baos = new ByteArrayOutputStream();
	for (int i = 0; i < digits.length(); i += 2) {
	    char c1 = digits.charAt(i);
	    if ((i+1) >= digits.length())
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.odd"));
	    char c2 = digits.charAt(i + 1);
	    byte b = 0;
	    if ((c1 >= '0') && (c1 <= '9'))
		b += ((c1 - '0') * 16);
	    else if ((c1 >= 'a') && (c1 <= 'f'))
		b += ((c1 - 'a' + 10) * 16);
	    else if ((c1 >= 'A') && (c1 <= 'F'))
		b += ((c1 - 'A' + 10) * 16);
	    else
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.bad"));
	    if ((c2 >= '0') && (c2 <= '9'))
		b += (c2 - '0');
	    else if ((c2 >= 'a') && (c2 <= 'f'))
		b += (c2 - 'a' + 10);
	    else if ((c2 >= 'A') && (c2 <= 'F'))
		b += (c2 - 'A' + 10);
	    else
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.bad"));
	    baos.write(b);
	}
	return (baos.toByteArray());

    }


    /**
     * Convert a byte array into a printable format containing a
     * String of hexadecimal digit characters (two per byte).
     *
     * @param bytes Byte array representation
     */
    public static String convert(byte bytes[]) {

	StringBuffer sb = new StringBuffer(bytes.length * 2);
	for (int i = 0; i < bytes.length; i++) {
	    sb.append(convertDigit((int) (bytes[i] >> 4)));
	    sb.append(convertDigit((int) (bytes[i] & 0x0f)));
	}
	return (sb.toString());

    }

    /**
     * Convert 4 hex digits to an int, and return the number of converted
     * bytes.
     *
     * @param hex Byte array containing exactly four hexadecimal digits
     *
     * @exception IllegalArgumentException if an invalid hexadecimal digit
     *  is included
     */
    public static int convert2Int( byte[] hex ) {
	// Code from Ajp11, from Apache's JServ
    
	// assert b.length==4
	// assert valid data
	int len;
	if(hex.length < 4 ) return 0;
	if( DEC[hex[0]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len = DEC[hex[0]];
	len = len << 4;
	if( DEC[hex[1]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[1]];
	len = len << 4;
	if( DEC[hex[2]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[2]];
	len = len << 4;
	if( DEC[hex[3]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[3]];
	return len;
    }



    /**
     * [Private] Convert the specified value (0 .. 15) to the corresponding
     * hexadecimal digit.
     *
     * @param value Value to be converted
     */
    private static char convertDigit(int value) {

	value &= 0x0f;
	if (value >= 10)
	    return ((char) (value - 10 + 'a'));
	else
	    return ((char) (value + '0'));

    }


}
