initial commit

hamrokhaanpaan/wp-includes/random_compat/random_bytes_dev_urandom.php

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+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * 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.
+ */
+
+if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
+    define('RANDOM_COMPAT_READ_BUFFER', 8);
+}
+
+if (!is_callable('random_bytes')) {
+    /**
+     * Unless open_basedir is enabled, use /dev/urandom for
+     * random numbers in accordance with best practices
+     *
+     * Why we use /dev/urandom and not /dev/random
+     * @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers
+     *
+     * @param int $bytes
+     *
+     * @throws Exception
+     *
+     * @return string
+     */
+    function random_bytes($bytes)
+    {
+        static $fp = null;
+        /**
+         * This block should only be run once
+         */
+        if (empty($fp)) {
+            /**
+             * We use /dev/urandom if it is a char device.
+             * We never fall back to /dev/random
+             */
+            $fp = fopen('/dev/urandom', 'rb');
+            if (!empty($fp)) {
+                $st = fstat($fp);
+                if (($st['mode'] & 0170000) !== 020000) {
+                    fclose($fp);
+                    $fp = false;
+                }
+            }
+
+            if (!empty($fp)) {
+                /**
+                 * stream_set_read_buffer() does not exist in HHVM
+                 *
+                 * If we don't set the stream's read buffer to 0, PHP will
+                 * internally buffer 8192 bytes, which can waste entropy
+                 *
+                 * stream_set_read_buffer returns 0 on success
+                 */
+                if (is_callable('stream_set_read_buffer')) {
+                    stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER);
+                }
+                if (is_callable('stream_set_chunk_size')) {
+                    stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER);
+                }
+            }
+        }
+
+        try {
+            $bytes = RandomCompat_intval($bytes);
+        } catch (TypeError $ex) {
+            throw new TypeError(
+                'random_bytes(): $bytes must be an integer'
+            );
+        }
+
+        if ($bytes < 1) {
+            throw new Error(
+                'Length must be greater than 0'
+            );
+        }
+
+        /**
+         * This if() block only runs if we managed to open a file handle
+         *
+         * It does not belong in an else {} block, because the above
+         * if (empty($fp)) line is logic that should only be run once per
+         * page load.
+         */
+        if (!empty($fp)) {
+            /**
+             * @var int
+             */
+            $remaining = $bytes;
+
+            /**
+             * @var string|bool
+             */
+            $buf = '';
+
+            /**
+             * We use fread() in a loop to protect against partial reads
+             */
+            do {
+                /**
+                 * @var string|bool
+                 */
+                $read = fread($fp, $remaining);
+                if (!is_string($read)) {
+                    if ($read === false) {
+                        /**
+                         * We cannot safely read from the file. Exit the
+                         * do-while loop and trigger the exception condition
+                         *
+                         * @var string|bool
+                         */
+                        $buf = false;
+                        break;
+                    }
+                }
+                /**
+                 * Decrease the number of bytes returned from remaining
+                 */
+                $remaining -= RandomCompat_strlen($read);
+                /**
+                 * @var string|bool
+                 */
+                $buf = $buf . $read;
+            } while ($remaining > 0);
+
+            /**
+             * Is our result valid?
+             */
+            if (is_string($buf)) {
+                if (RandomCompat_strlen($buf) === $bytes) {
+                    /**
+                     * Return our random entropy buffer here:
+                     */
+                    return $buf;
+                }
+            }
+        }
+
+        /**
+         * If we reach here, PHP has failed us.
+         */
+        throw new Exception(
+            'Error reading from source device'
+        );
+    }
+}