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167 lines
5.3 KiB
167 lines
5.3 KiB
<?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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