noVNC/core/base64.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// From: http://hg.mozilla.org/mozilla-central/raw-file/ec10630b1a54/js/src/devtools/jint/sunspider/string-base64.js

import * as Log from './util/logging.js';

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

    encode(data) {
        "use strict";
        let result = '';
        const length = data.length;
        const lengthpad = (length % 3);
        // Convert every three bytes to 4 ascii characters.

        for (let i = 0; i < (length - 2); i += 3) {
            result += this.toBase64Table[data[i] >> 2];
            result += this.toBase64Table[((data[i] & 0x03) << 4) + (data[i + 1] >> 4)];
            result += this.toBase64Table[((data[i + 1] & 0x0f) << 2) + (data[i + 2] >> 6)];
            result += this.toBase64Table[data[i + 2] & 0x3f];
        }

        // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
        const j = length - lengthpad;
        if (lengthpad === 2) {
            result += this.toBase64Table[data[j] >> 2];
            result += this.toBase64Table[((data[j] & 0x03) << 4) + (data[j + 1] >> 4)];
            result += this.toBase64Table[(data[j + 1] & 0x0f) << 2];
            result += this.toBase64Table[64];
        } else if (lengthpad === 1) {
            result += this.toBase64Table[data[j] >> 2];
            result += this.toBase64Table[(data[j] & 0x03) << 4];
            result += this.toBase64Table[64];
            result += this.toBase64Table[64];
        }

        return result;
    },

    /* Convert Base64 data to a string */
    /* eslint-disable comma-spacing */
    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
    ],
    /* eslint-enable comma-spacing */

    decode(data, offset) {
        offset = typeof(offset) !== 'undefined' ? offset : 0;

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

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

        // Convert one by one.

        let leftbits = 0; // number of bits decoded, but yet to be appended
        let leftdata = 0; // bits decoded, but yet to be appended
        for (let idx = 0, i = offset; i < data.length; i++) {
            const c = this.toBinaryTable[data.charCodeAt(i) & 0x7f];
            const padding = (data.charAt(i) === this.base64Pad);
            // Skip illegal characters and whitespace
            if (c === -1) {
                Log.Error("Illegal character code " + data.charCodeAt(i) + " at position " + 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) {
            const err = new Error('Corrupted base64 string');
            err.name = 'Base64-Error';
            throw err;
        }

        return result;
    }
}; /* End of Base64 namespace */