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1 <?php 2 /** 3 * Random_* Compatibility Library 4 * for using the new PHP 7 random_* API in PHP 5 projects 5 * 6 * The MIT License (MIT) 7 * 8 * Copyright (c) 2015 - 2017 Paragon Initiative Enterprises 9 * 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: 16 * 17 * The above copyright notice and this permission notice shall be included in 18 * all copies or substantial portions of the Software. 19 * 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 26 * SOFTWARE. 27 */ 28 29 if (!defined('RANDOM_COMPAT_READ_BUFFER')) { 30 define('RANDOM_COMPAT_READ_BUFFER', 8); 31 } 32 33 if (!is_callable('random_bytes')) { 34 /** 35 * Unless open_basedir is enabled, use /dev/urandom for 36 * random numbers in accordance with best practices 37 * 38 * Why we use /dev/urandom and not /dev/random 39 * @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers 40 * 41 * @param int $bytes 42 * 43 * @throws Exception 44 * 45 * @return string 46 */ 47 function random_bytes($bytes) 48 { 49 static $fp = null; 50 /** 51 * This block should only be run once 52 */ 53 if (empty($fp)) { 54 /** 55 * We use /dev/urandom if it is a char device. 56 * We never fall back to /dev/random 57 */ 58 $fp = fopen('/dev/urandom', 'rb'); 59 if (!empty($fp)) { 60 $st = fstat($fp); 61 if (($st['mode'] & 0170000) !== 020000) { 62 fclose($fp); 63 $fp = false; 64 } 65 } 66 67 if (!empty($fp)) { 68 /** 69 * stream_set_read_buffer() does not exist in HHVM 70 * 71 * If we don't set the stream's read buffer to 0, PHP will 72 * internally buffer 8192 bytes, which can waste entropy 73 * 74 * stream_set_read_buffer returns 0 on success 75 */ 76 if (is_callable('stream_set_read_buffer')) { 77 stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER); 78 } 79 if (is_callable('stream_set_chunk_size')) { 80 stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER); 81 } 82 } 83 } 84 85 try { 86 $bytes = RandomCompat_intval($bytes); 87 } catch (TypeError $ex) { 88 throw new TypeError( 89 'random_bytes(): $bytes must be an integer' 90 ); 91 } 92 93 if ($bytes < 1) { 94 throw new Error( 95 'Length must be greater than 0' 96 ); 97 } 98 99 /** 100 * This if() block only runs if we managed to open a file handle 101 * 102 * It does not belong in an else {} block, because the above 103 * if (empty($fp)) line is logic that should only be run once per 104 * page load. 105 */ 106 if (!empty($fp)) { 107 /** 108 * @var int 109 */ 110 $remaining = $bytes; 111 112 /** 113 * @var string|bool 114 */ 115 $buf = ''; 116 117 /** 118 * We use fread() in a loop to protect against partial reads 119 */ 120 do { 121 /** 122 * @var string|bool 123 */ 124 $read = fread($fp, $remaining); 125 if (!is_string($read)) { 126 if ($read === false) { 127 /** 128 * We cannot safely read from the file. Exit the 129 * do-while loop and trigger the exception condition 130 * 131 * @var string|bool 132 */ 133 $buf = false; 134 break; 135 } 136 } 137 /** 138 * Decrease the number of bytes returned from remaining 139 */ 140 $remaining -= RandomCompat_strlen($read); 141 /** 142 * @var string|bool 143 */ 144 $buf = $buf . $read; 145 } while ($remaining > 0); 146 147 /** 148 * Is our result valid? 149 */ 150 if (is_string($buf)) { 151 if (RandomCompat_strlen($buf) === $bytes) { 152 /** 153 * Return our random entropy buffer here: 154 */ 155 return $buf; 156 } 157 } 158 } 159 160 /** 161 * If we reach here, PHP has failed us. 162 */ 163 throw new Exception( 164 'Error reading from source device' 165 ); 166 } 167 }
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