Random compat

random_compat.php

if (!function_exists('random_bytes')) {
    function random_bytes($length)
    {
        $buffer = '';
        $valid = false;
        if (function_exists('mcrypt_create_iv') && !defined('PHALANGER')) {
            $buffer = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
            if ($buffer) {
                $valid = true;
            }
        }
        if (!$valid && function_exists('openssl_random_pseudo_bytes')) {
            $bytes = openssl_random_pseudo_bytes($length, $strong);
            if ($bytes && true === $strong) {
                $buffer = $bytes;
                $valid = true;
            }
        }
        if (!$valid && @is_readable('/dev/urandom')) {
            $handle = fopen('/dev/urandom', 'r');
            $len = strlen($buffer);
            while ($len < $length) {
                $buffer .= fread($handle, $length - $len);
                $len = strlen($buffer);
            }
            fclose($handle);
            if ($len >= $length) {
                $valid = true;
            }
        }
        if (!$valid || strlen($buffer) < $length) {
            $len = strlen($buffer);
            for ($i = 0; $i < $length; $i++) {
                if ($i < $len) {
                    $buffer[$i] = $buffer[$i] ^ chr(mt_rand(0, 255));
                } else {
                    $buffer .= chr(mt_rand(0, 255));
                }
            }
        }

        return $buffer;
    }
}

if (!function_exists('random_int')) {
    function random_int($min, $max)
    {
        $min = (int) $min;
        $max = (int) $max;
        $range = $max - $min;
        if ($range <= 0) {
            return $min;
        }
        $bits = (int) ceil(log($range, 2));
        $bytes = (int) max(ceil($bits / 8), 1);
        if ($bits === 63) {
            $mask = 0x7fffffffffffffff;
        } else {
            $mask = (int) (pow(2, $bits) - 1);
        }
        $num = 0;
        do {
            $num = hexdec(bin2hex(random_bytes($bytes))) & $mask;
        } while ($num > $range);

        return $num + $min;
    }
}

Can you explain how your random_int() function works? I'm not following the logic.

@scottchiefbaker The methods that the code is based on have some comments:
https://github.com/ircmaxell/RandomLib/blob/master/lib/RandomLib/Generator.php#L166
https://github.com/ircmaxell/random_compat/blob/master/lib/random.php#L44

Generally speaking, the input values are cast as integers and checked. The range is determined (the number of possible integers). The total amount of bits/bytes is found, in order to hold a value up to the maximum range value. Then a bitmask is created for the "&" operation inside the do loop.

Within the do loop, enough random bytes are generated (from the random_bytes method in this case), converted to hex, then converted to decimal. Then the mask is applied. This is the same as the methods referenced above, and it removes unused bits.

The loop exits as long as the number is within the valid range. Finally adding the generated integer (within range) to the "min" value produces the result.