<?php
/**
 * Random_* Compatibility Library
 * for using the new PHP 7 random_* API in PHP 5 projects
 *
 * @version 2.0.10
 * @released 2017-03-13
 *
 * 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 ( ! defined('PHP_VERSION_ID'))
{
	// This constant was introduced in PHP 5.2.7
	$RandomCompatversion = array_map('intval', explode('.', PHP_VERSION));
	define('PHP_VERSION_ID', $RandomCompatversion[0] * 10000 + $RandomCompatversion[1] * 100 + $RandomCompatversion[2]);
	$RandomCompatversion = null;
}

// PHP 7.0.0 and newer have these functions natively.
if (PHP_VERSION_ID >= 70000)
{
	return;
}

defined('RANDOM_COMPAT_READ_BUFFER') OR define('RANDOM_COMPAT_READ_BUFFER', 8);

$random_compat_dir = dirname(__FILE__);

require_once $random_compat_dir.'/byte_safe_strings.php';
require_once $random_compat_dir.'/cast_to_int.php';
require_once $random_compat_dir.'/error_polyfill.php';

if ( ! is_callable('random_bytes'))
{
	/**
	 * PHP 5.2.0 - 5.6.x way to implement random_bytes()
	 *
	 * We use conditional statements here to define the function in accordance
	 * to the operating environment. It's a micro-optimization.
	 *
	 * In order of preference:
	 *   1. Use libsodium if available.
	 *   2. fread() /dev/urandom if available (never on Windows)
	 *   3. mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM)
	 *   4. COM('CAPICOM.Utilities.1')->GetRandom()
	 *
	 * See RATIONALE.md for our reasoning behind this particular order
	 */
	if (extension_loaded('libsodium'))
	{
		// See random_bytes_libsodium.php
		if (PHP_VERSION_ID >= 50300 && is_callable('\\Sodium\\randombytes_buf'))
		{
			require_once $random_compat_dir.'/random_bytes_libsodium.php';
		}
		elseif (method_exists('Sodium', 'randombytes_buf'))
		{
			require_once $random_compat_dir.'/random_bytes_libsodium_legacy.php';
		}
	}
	
	/**
	 * Reading directly from /dev/urandom:
	 */
	if (DIRECTORY_SEPARATOR === '/')
	{
		// DIRECTORY_SEPARATOR === '/' on Unix-like OSes -- this is a fast
		// way to exclude Windows.
		$RandomCompatUrandom  = true;
		$RandomCompat_basedir = ini_get('open_basedir');
		
		if ( ! empty($RandomCompat_basedir))
		{
			$RandomCompat_open_basedir = explode(PATH_SEPARATOR, strtolower($RandomCompat_basedir));
			$RandomCompatUrandom       = (array() !== array_intersect(array(
				'/dev',
				'/dev/',
				'/dev/urandom'
			), $RandomCompat_open_basedir));
			$RandomCompat_open_basedir = null;
		}
		
		if ( ! is_callable('random_bytes') && $RandomCompatUrandom && @is_readable('/dev/urandom'))
		{
			// Error suppression on is_readable() in case of an open_basedir
			// or safe_mode failure. All we care about is whether or not we
			// can read it at this point. If the PHP environment is going to
			// panic over trying to see if the file can be read in the first
			// place, that is not helpful to us here.
			
			// See random_bytes_dev_urandom.php
			require_once $random_compat_dir.'/random_bytes_dev_urandom.php';
		}
		// Unset variables after use
		$RandomCompat_basedir = null;
	}
	else
	{
		$RandomCompatUrandom = false;
	}
	
	/**
	 * mcrypt_create_iv()
	 *
	 * We only want to use mcypt_create_iv() if:
	 *
	 * - random_bytes() hasn't already been defined
	 * - the mcrypt extensions is loaded
	 * - One of these two conditions is true:
	 *   - We're on Windows (DIRECTORY_SEPARATOR !== '/')
	 *   - We're not on Windows and /dev/urandom is readabale
	 *     (i.e. we're not in a chroot jail)
	 * - Special case:
	 *   - If we're not on Windows, but the PHP version is between
	 *     5.6.10 and 5.6.12, we don't want to use mcrypt. It will
	 *     hang indefinitely. This is bad.
	 *   - If we're on Windows, we want to use PHP >= 5.3.7 or else
	 *     we get insufficient entropy errors.
	 */
	if ( ! is_callable('random_bytes') && 
	// Windows on PHP < 5.3.7 is broken, but non-Windows is not known to be.
		(DIRECTORY_SEPARATOR === '/' || PHP_VERSION_ID >= 50307) && 
	// Prevent this code from hanging indefinitely on non-Windows;
		
	// see https://bugs.php.net/bug.php?id=69833
		(DIRECTORY_SEPARATOR !== '/' || (PHP_VERSION_ID <= 50609 || PHP_VERSION_ID >= 50613)) && extension_loaded('mcrypt'))
	{
		// See random_bytes_mcrypt.php
		require_once $random_compat_dir.'/random_bytes_mcrypt.php';
	}
	$RandomCompatUrandom = null;
	
	/**
	 * This is a Windows-specific fallback, for when the mcrypt extension
	 * isn't loaded.
	 */
	if ( ! is_callable('random_bytes') && extension_loaded('com_dotnet') && class_exists('COM'))
	{
		$RandomCompat_disabled_classes = preg_split('#\s*,\s*#', strtolower(ini_get('disable_classes')));
		
		if ( ! in_array('com', $RandomCompat_disabled_classes))
		{
			try
			{
				$RandomCompatCOMtest = new COM('CAPICOM.Utilities.1');
				if (method_exists($RandomCompatCOMtest, 'GetRandom'))
				{
					// See random_bytes_com_dotnet.php
					require_once $random_compat_dir.'/random_bytes_com_dotnet.php';
				}
			}
			catch (com_exception $e)
			{
				// Don't try to use it.
			}
		}
		$RandomCompat_disabled_classes = null;
		$RandomCompatCOMtest           = null;
	}
	
	/**
	 * openssl_random_pseudo_bytes()
	 */
	if ((
	// Unix-like with PHP >= 5.3.0 or
		(DIRECTORY_SEPARATOR === '/' && PHP_VERSION_ID >= 50300) || 
	// Windows with PHP >= 5.4.1
		PHP_VERSION_ID >= 50401) && !function_exists('random_bytes') && extension_loaded('openssl'))
	{
		// See random_bytes_openssl.php
		require_once $random_compat_dir.'/random_bytes_openssl.php';
	}
	
	/**
	 * throw new Exception
	 */
	if ( ! is_callable('random_bytes'))
	{
		/**
		 * We don't have any more options, so let's throw an exception right now
		 * and hope the developer won't let it fail silently.
		 *
		 * @param mixed $length
		 * @psalm-suppress MissingReturnType
		 * @throws Exception
		 * @return string
		 */
		function random_bytes($length)
		{
			unset($length); // Suppress "variable not used" warnings.
			throw new Exception('There is no suitable CSPRNG installed on your system');
			return '';
		}
	}
}

if ( ! is_callable('random_int'))
{
	require_once $random_compat_dir.'/random_int.php';
}

$random_compat_dir = null;
