comparison vendor/paragonie/random_compat/lib/random_int.php @ 0:4c8ae668cc8c

Initial import (non-working)

+<?php
+
+if (!is_callable('random_int')) {
+    /**
+     * 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.
+     */
+
+    /**
+     * Fetch a random integer between $min and $max inclusive
+     *
+     * @param int $min
+     * @param int $max
+     *
+     * @throws Exception
+     *
+     * @return int
+     */
+    function random_int($min, $max)
+    {
+        /**
+         * Type and input logic checks
+         *
+         * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)
+         * (non-inclusive), it will sanely cast it to an int. If you it's equal to
+         * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats
+         * lose precision, so the <= and => operators might accidentally let a float
+         * through.
+         */
+
+        try {
+            $min = RandomCompat_intval($min);
+        } catch (TypeError $ex) {
+            throw new TypeError(
+                'random_int(): $min must be an integer'
+            );
+        }
+
+        try {
+            $max = RandomCompat_intval($max);
+        } catch (TypeError $ex) {
+            throw new TypeError(
+                'random_int(): $max must be an integer'
+            );
+        }
+
+        /**
+         * Now that we've verified our weak typing system has given us an integer,
+         * let's validate the logic then we can move forward with generating random
+         * integers along a given range.
+         */
+        if ($min > $max) {
+            throw new Error(
+                'Minimum value must be less than or equal to the maximum value'
+            );
+        }
+
+        if ($max === $min) {
+            return $min;
+        }
+
+        /**
+         * Initialize variables to 0
+         *
+         * We want to store:
+         * $bytes => the number of random bytes we need
+         * $mask => an integer bitmask (for use with the &) operator
+         *          so we can minimize the number of discards
+         */
+        $attempts = $bits = $bytes = $mask = $valueShift = 0;
+
+        /**
+         * At this point, $range is a positive number greater than 0. It might
+         * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to
+         * a float and we will lose some precision.
+         */
+        $range = $max - $min;
+
+        /**
+         * Test for integer overflow:
+         */
+        if (!is_int($range)) {
+
+            /**
+             * Still safely calculate wider ranges.
+             * Provided by @CodesInChaos, @oittaa
+             *
+             * @ref https://gist.github.com/CodesInChaos/03f9ea0b58e8b2b8d435
+             *
+             * We use ~0 as a mask in this case because it generates all 1s
+             *
+             * @ref https://eval.in/400356 (32-bit)
+             * @ref http://3v4l.org/XX9r5  (64-bit)
+             */
+            $bytes = PHP_INT_SIZE;
+            $mask = ~0;
+
+        } else {
+
+            /**
+             * $bits is effectively ceil(log($range, 2)) without dealing with
+             * type juggling
+             */
+            while ($range > 0) {
+                if ($bits % 8 === 0) {
+                    ++$bytes;
+                }
+                ++$bits;
+                $range >>= 1;
+                $mask = $mask << 1 | 1;
+            }
+            $valueShift = $min;
+        }
+
+        $val = 0;
+        /**
+         * Now that we have our parameters set up, let's begin generating
+         * random integers until one falls between $min and $max
+         */
+        do {
+            /**
+             * The rejection probability is at most 0.5, so this corresponds
+             * to a failure probability of 2^-128 for a working RNG
+             */
+            if ($attempts > 128) {
+                throw new Exception(
+                    'random_int: RNG is broken - too many rejections'
+                );
+            }
+
+            /**
+             * Let's grab the necessary number of random bytes
+             */
+            $randomByteString = random_bytes($bytes);
+
+            /**
+             * Let's turn $randomByteString into an integer
+             *
+             * This uses bitwise operators (<< and |) to build an integer
+             * out of the values extracted from ord()
+             *
+             * Example: [9F] | [6D] | [32] | [0C] =>
+             *   159 + 27904 + 3276800 + 201326592 =>
+             *   204631455
+             */
+            $val &= 0;
+            for ($i = 0; $i < $bytes; ++$i) {
+                $val |= ord($randomByteString[$i]) << ($i * 8);
+            }
+
+            /**
+             * Apply mask
+             */
+            $val &= $mask;
+            $val += $valueShift;
+
+            ++$attempts;
+            /**
+             * If $val overflows to a floating point number,
+             * ... or is larger than $max,
+             * ... or smaller than $min,
+             * then try again.
+             */
+        } while (!is_int($val) || $val > $max || $val < $min);
+
+        return (int)$val;
+    }
+}