<?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'))
{
	/**
	 * If the libsodium PHP extension is loaded, we'll use it above any other
	 * solution.
	 *
	 * libsodium-php project:
	 * @see 	https://github.com/jedisct1/libsodium-php
	 * @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');
		}
		
		/**
		 * \Sodium\randombytes_buf() doesn't allow more than 2147483647 bytes to be
		 * generated in one invocation.
		 */
		if ($bytes > 2147483647)
		{
			$buf = '';
			for ($i = 0; $i < $bytes; $i += 1073741824)
			{
				$n = ($bytes - $i) > 1073741824 ? 1073741824 : $bytes - $i;
				$buf .= \Sodium\randombytes_buf($n);
			}
		}
		else
		{
			$buf = \Sodium\randombytes_buf($bytes);
		}
		
		if ($buf !== false)
		{
			if (RandomCompat_strlen($buf) === $bytes)
			{
				return $buf;
			}
		}
		
		/**
		 * If we reach here, PHP has failed us.
		 */
		throw new Exception('Could not gather sufficient random data');
	}
}
