3 * Random_* Compatibility Library
4 * for using the new PHP 7 random_* API in PHP 5 projects
6 * The MIT License (MIT)
8 * Copyright (c) 2015 - 2018 Paragon Initiative Enterprises
10 * Permission is hereby granted, free of charge, to any person obtaining a copy
11 * of this software and associated documentation files (the "Software"), to deal
12 * in the Software without restriction, including without limitation the rights
13 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
14 * copies of the Software, and to permit persons to whom the Software is
15 * furnished to do so, subject to the following conditions:
17 * The above copyright notice and this permission notice shall be included in
18 * all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
23 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
25 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
30 define('RANDOM_COMPAT_READ_BUFFER', 8);
33 if (!is_callable('random_bytes')) {
35 * Unless open_basedir is enabled, use /dev/urandom for
36 * random numbers in accordance with best practices
38 * Why we use /dev/urandom and not /dev/random
39 * @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers
47 function random_bytes($bytes)
49 /** @var resource $fp */
53 * This block should only be run once
57 * We use /dev/urandom if it is a char device.
58 * We never fall back to /dev/random
60 /** @var resource|bool $fp */
61 $fp = fopen('/dev/urandom', 'rb');
62 if (is_resource($fp)) {
63 /** @var array<string, int> $st */
65 if (($st['mode'] & 0170000) !== 020000) {
71 if (is_resource($fp)) {
73 * stream_set_read_buffer() does not exist in HHVM
75 * If we don't set the stream's read buffer to 0, PHP will
76 * internally buffer 8192 bytes, which can waste entropy
78 * stream_set_read_buffer returns 0 on success
80 if (is_callable('stream_set_read_buffer')) {
81 stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER);
83 if (is_callable('stream_set_chunk_size')) {
84 stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER);
90 /** @var int $bytes */
91 $bytes = RandomCompat_intval($bytes);
92 } catch (TypeError $ex) {
94 'random_bytes(): $bytes must be an integer'
100 'Length must be greater than 0'
105 * This if() block only runs if we managed to open a file handle
107 * It does not belong in an else {} block, because the above
108 * if (empty($fp)) line is logic that should only be run once per
111 if (is_resource($fp)) {
123 * We use fread() in a loop to protect against partial reads
129 $read = fread($fp, $remaining);
130 if (!is_string($read)) {
131 if ($read === false) {
133 * We cannot safely read from the file. Exit the
134 * do-while loop and trigger the exception condition
143 * Decrease the number of bytes returned from remaining
145 $remaining -= RandomCompat_strlen($read);
150 } while ($remaining > 0);
153 * Is our result valid?
155 if (is_string($buf)) {
156 if (RandomCompat_strlen($buf) === $bytes) {
158 * Return our random entropy buffer here:
166 * If we reach here, PHP has failed us.
169 'Error reading from source device'