base64.js

/*
 * Modified from:
 * http://lxr.mozilla.org/mozilla/source/extensions/xml-rpc/src/nsXmlRpcClient.js#956
 */

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla XML-RPC Client component.
 *
 * The Initial Developer of the Original Code is
 * Digital Creations 2, Inc.
 * Portions created by the Initial Developer are Copyright (C) 2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Martijn Pieters <mj@digicool.com> (original author)
 *   Samuel Sieb <samuel@sieb.net>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

"use strict";
/*jslint white: false, bitwise: false, plusplus: false */
/*global console */

var Base64 = {

/* Convert data (an array of integers) to a Base64 string. */
toBase64Table : 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/',
base64Pad     : '=',

encode: function (data) {
    var result = '',
        chrTable = Base64.toBase64Table.split(''),
        pad = Base64.base64Pad,
        length = data.length,
        i;
    // Convert every three bytes to 4 ascii characters.
    for (i = 0; i < (length - 2); i += 3) {
        result += chrTable[data[i] >> 2];
        result += chrTable[((data[i] & 0x03) << 4) + (data[i+1] >> 4)];
        result += chrTable[((data[i+1] & 0x0f) << 2) + (data[i+2] >> 6)];
        result += chrTable[data[i+2] & 0x3f];
    }

    // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
    if (length%3) {
        i = length - (length%3);
        result += chrTable[data[i] >> 2];
        if ((length%3) === 2) {
            result += chrTable[((data[i] & 0x03) << 4) + (data[i+1] >> 4)];
            result += chrTable[(data[i+1] & 0x0f) << 2];
            result += pad;
        } else {
            result += chrTable[(data[i] & 0x03) << 4];
            result += pad + pad;
        }
    }

    return result;
},

/* Convert Base64 data to a string */
toBinaryTable : [
    -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,-1,62, -1,-1,-1,63,
    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-1,-1,
    -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
    15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
],

decode: function (data, offset) {
    offset = typeof(offset) !== 'undefined' ? offset : 0;
    var binTable = Base64.toBinaryTable,
        pad = Base64.base64Pad,
        result, result_length, idx, i, c, padding,
        leftbits = 0, // number of bits decoded, but yet to be appended
        leftdata = 0, // bits decoded, but yet to be appended
        data_length = data.indexOf('=') - offset;

    if (data_length < 0) { data_length = data.length - offset; }

    /* Every four characters is 3 resulting numbers */
    result_length = (data_length >> 2) * 3 + Math.floor((data_length%4)/1.5);
    result = new Array(result_length);

    // Convert one by one.
    for (idx = 0, i = offset; i < data.length; i++) {
        c = binTable[data.charCodeAt(i) & 0x7f];
        padding = (data.charAt(i) === pad);
        // Skip illegal characters and whitespace
        if (c === -1) {
            console.error("Illegal character '" + data.charCodeAt(i) + "'");
            continue;
        }
        
        // Collect data into leftdata, update bitcount
        leftdata = (leftdata << 6) | c;
        leftbits += 6;

        // If we have 8 or more bits, append 8 bits to the result
        if (leftbits >= 8) {
            leftbits -= 8;
            // Append if not padding.
            if (!padding) {
                result[idx++] = (leftdata >> leftbits) & 0xff;
            }
            leftdata &= (1 << leftbits) - 1;
        }
    }

    // If there are any bits left, the base64 string was corrupted
    if (leftbits) {
        throw {name: 'Base64-Error', 
               message: 'Corrupted base64 string'};
    }

    return result;
}

}; /* End of Base64 namespace */