3 if (!is_callable('random_int')) {
5 * Random_* Compatibility Library
6 * for using the new PHP 7 random_* API in PHP 5 projects
8 * The MIT License (MIT)
10 * Copyright (c) 2015 - 2018 Paragon Initiative Enterprises
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this software and associated documentation files (the "Software"), to deal
14 * in the Software without restriction, including without limitation the rights
15 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
16 * copies of the Software, and to permit persons to whom the Software is
17 * furnished to do so, subject to the following conditions:
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
27 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32 * Fetch a random integer between $min and $max inclusive
41 function random_int($min, $max)
44 * Type and input logic checks
46 * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)
47 * (non-inclusive), it will sanely cast it to an int. If you it's equal to
48 * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats
49 * lose precision, so the <= and => operators might accidentally let a float
55 $min = RandomCompat_intval($min);
56 } catch (TypeError $ex) {
58 'random_int(): $min must be an integer'
64 $max = RandomCompat_intval($max);
65 } catch (TypeError $ex) {
67 'random_int(): $max must be an integer'
72 * Now that we've verified our weak typing system has given us an integer,
73 * let's validate the logic then we can move forward with generating random
74 * integers along a given range.
78 'Minimum value must be less than or equal to the maximum value'
87 * Initialize variables to 0
90 * $bytes => the number of random bytes we need
91 * $mask => an integer bitmask (for use with the &) operator
92 * so we can minimize the number of discards
94 $attempts = $bits = $bytes = $mask = $valueShift = 0;
95 /** @var int $attempts */
97 /** @var int $bytes */
99 /** @var int $valueShift */
102 * At this point, $range is a positive number greater than 0. It might
103 * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to
104 * a float and we will lose some precision.
106 * @var int|float $range
108 $range = $max - $min;
111 * Test for integer overflow:
113 if (!is_int($range)) {
116 * Still safely calculate wider ranges.
117 * Provided by @CodesInChaos, @oittaa
119 * @ref https://gist.github.com/CodesInChaos/03f9ea0b58e8b2b8d435
121 * We use ~0 as a mask in this case because it generates all 1s
123 * @ref https://eval.in/400356 (32-bit)
124 * @ref http://3v4l.org/XX9r5 (64-bit)
126 $bytes = PHP_INT_SIZE;
127 /** @var int $mask */
133 * $bits is effectively ceil(log($range, 2)) without dealing with
137 if ($bits % 8 === 0) {
142 /** @var int $mask */
143 $mask = $mask << 1 | 1;
151 * Now that we have our parameters set up, let's begin generating
152 * random integers until one falls between $min and $max
154 /** @psalm-suppress RedundantCondition */
157 * The rejection probability is at most 0.5, so this corresponds
158 * to a failure probability of 2^-128 for a working RNG
160 if ($attempts > 128) {
162 'random_int: RNG is broken - too many rejections'
167 * Let's grab the necessary number of random bytes
169 $randomByteString = random_bytes($bytes);
172 * Let's turn $randomByteString into an integer
174 * This uses bitwise operators (<< and |) to build an integer
175 * out of the values extracted from ord()
177 * Example: [9F] | [6D] | [32] | [0C] =>
178 * 159 + 27904 + 3276800 + 201326592 =>
182 for ($i = 0; $i < $bytes; ++$i) {
183 $val |= ord($randomByteString[$i]) << ($i * 8);
195 * If $val overflows to a floating point number,
196 * ... or is larger than $max,
197 * ... or smaller than $min,
200 } while (!is_int($val) || $val > $max || $val < $min);