<?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.
 */
defined('BASEPATH') OR exit('No direct script access allowed');

if (!is_callable('random_bytes'))
{
	/**
	 * Powered by ext/mcrypt (and thankfully NOT libmcrypt)
	 *
	 * @see https://bugs.php.net/bug.php?id=55169
	 * @see https://github.com/php/php-src/blob/c568ffe5171d942161fc8dda066bce844bdef676/ext/mcrypt/mcrypt.c#L1321-L1386
	 *
	 * @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');
		}
		
		$buf = @mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM);
		if ($buf !== false && RandomCompat_strlen($buf) === $bytes)
		{
			/**
			 * Return our random entropy buffer here:
			 */
			return $buf;
		}
		
		/**
		 * If we reach here, PHP has failed us.
		 */
		throw new Exception('Could not gather sufficient random data');
	}
}
