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<?php
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/**
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* Random_* Compatibility Library
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* for using the new PHP 7 random_* API in PHP 5 projects
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 - 2017 Paragon Initiative Enterprises
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
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define('RANDOM_COMPAT_READ_BUFFER', 8);
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}
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if (!is_callable('random_bytes')) {
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/**
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* Unless open_basedir is enabled, use /dev/urandom for
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* random numbers in accordance with best practices
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*
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* Why we use /dev/urandom and not /dev/random
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* @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers
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*
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* @param int $bytes
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*
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* @throws Exception
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*
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* @return string
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*/
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function random_bytes($bytes)
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{
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static $fp = null;
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/**
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* This block should only be run once
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*/
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if (empty($fp)) {
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/**
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* We use /dev/urandom if it is a char device.
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* We never fall back to /dev/random
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*/
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$fp = fopen('/dev/urandom', 'rb');
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if (!empty($fp)) {
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$st = fstat($fp);
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if (($st['mode'] & 0170000) !== 020000) {
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fclose($fp);
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$fp = false;
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}
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}
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if (!empty($fp)) {
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/**
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* stream_set_read_buffer() does not exist in HHVM
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*
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* If we don't set the stream's read buffer to 0, PHP will
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* internally buffer 8192 bytes, which can waste entropy
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*
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* stream_set_read_buffer returns 0 on success
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*/
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if (is_callable('stream_set_read_buffer')) {
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stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER);
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}
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if (is_callable('stream_set_chunk_size')) {
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stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER);
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}
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}
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}
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try {
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$bytes = RandomCompat_intval($bytes);
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} catch (TypeError $ex) {
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throw new TypeError(
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'random_bytes(): $bytes must be an integer'
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);
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}
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if ($bytes < 1) {
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throw new Error(
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'Length must be greater than 0'
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);
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}
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/**
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* This if() block only runs if we managed to open a file handle
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*
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* It does not belong in an else {} block, because the above
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* if (empty($fp)) line is logic that should only be run once per
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* page load.
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*/
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if (!empty($fp)) {
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/**
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* @var int
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*/
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$remaining = $bytes;
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/**
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* @var string|bool
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*/
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$buf = '';
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/**
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* We use fread() in a loop to protect against partial reads
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*/
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do {
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/**
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* @var string|bool
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*/
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$read = fread($fp, $remaining);
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if (!is_string($read)) {
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if ($read === false) {
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/**
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* We cannot safely read from the file. Exit the
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* do-while loop and trigger the exception condition
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*
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* @var string|bool
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*/
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$buf = false;
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break;
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}
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}
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/**
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* Decrease the number of bytes returned from remaining
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*/
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$remaining -= RandomCompat_strlen($read);
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/**
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* @var string|bool
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*/
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$buf = $buf . $read;
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} while ($remaining > 0);
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/**
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* Is our result valid?
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*/
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if (is_string($buf)) {
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if (RandomCompat_strlen($buf) === $bytes) {
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/**
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* Return our random entropy buffer here:
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*/
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return $buf;
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}
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}
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}
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/**
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* If we reach here, PHP has failed us.
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*/
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throw new Exception(
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'Error reading from source device'
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);
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}
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}
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