<?php

/**

 * Random_* Compatibility Library 

 * for using the new PHP 7 random_* API in PHP 5 projects

 * 

 * The MIT License (MIT)

 * 

 * Copyright (c) 2015 - 2017 Paragon Initiative Enterprises

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

if (!is_callable('random_bytes')) {

    /**

     * Windows with PHP < 5.3.0 will not have the function

     * openssl_random_pseudo_bytes() available, so let's use

     * CAPICOM to work around this deficiency.

     *

     * @param int $bytes

     *

     * @throws Exception

     *

     * @return string

     */

    function random_bytes($bytes)

    {

        try {

            $bytes = RandomCompat_intval($bytes);

        } catch (TypeError $ex) {

            throw new TypeError(

                'random_bytes(): $bytes must be an integer'

            );

        }

        if ($bytes < 1) {

            throw new Error(

                'Length must be greater than 0'

            );

        }

        $buf = '';

        if (!class_exists('COM')) {

            throw new Error(

                'COM does not exist'

            );

        }

        $util = new COM('CAPICOM.Utilities.1');

        $execCount = 0;

        /**

         * Let's not let it loop forever. If we run N times and fail to

         * get N bytes of random data, then CAPICOM has failed us.

         */

        do {

            $buf .= base64_decode($util->GetRandom($bytes, 0));

            if (RandomCompat_strlen($buf) >= $bytes) {

                /**

                 * Return our random entropy buffer here:

                 */

                return RandomCompat_substr($buf, 0, $bytes);

            }

            ++$execCount;

        } while ($execCount < $bytes);

        /**

         * If we reach here, PHP has failed us.

         */

        throw new Exception(

            'Could not gather sufficient random data'

        );

    }

}