From 9e2b2a32fd0e967ad3184e9a5d091a29953acb91 Mon Sep 17 00:00:00 2001 From: Frederic Guillot Date: Wed, 25 Oct 2017 16:22:10 -0700 Subject: Include composer dependencies in repo --- vendor/paragonie/random_compat/lib/random_int.php | 191 ++++++++++++++++++++++ 1 file changed, 191 insertions(+) create mode 100644 vendor/paragonie/random_compat/lib/random_int.php (limited to 'vendor/paragonie/random_compat/lib/random_int.php') diff --git a/vendor/paragonie/random_compat/lib/random_int.php b/vendor/paragonie/random_compat/lib/random_int.php new file mode 100644 index 00000000..fd3ef87a --- /dev/null +++ b/vendor/paragonie/random_compat/lib/random_int.php @@ -0,0 +1,191 @@ + 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; + } + + /** + * 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); + if ($randomByteString === false) { + throw new Exception( + 'Random number generator failure' + ); + } + + /** + * 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; +} -- cgit v1.2.3