php whitelist that supports cidr notation

cidr_whitelist.php

<?php

function is_whitelisted($remote_ip) {
    $whitelisted = false;
    $remote_ip = sprintf("%u", ip2long($remote_ip));
    $records = ["127.0.0.0/10", "10.0.0.1", "192.168.1.0/24"];
    foreach ($records as $record) {
        $ip = $record;
        $cidr = 32;
        if (strpos($record, "/"))
            list($ip, $cidr) = explode("/", $record);
        $start = sprintf("%u", ip2long($ip));
        $num_hosts = pow(2, 32 - $cidr) - 1;
        if ($remote_ip >= $start && $remote_ip <= $start + $num_hosts) {
            $whitelisted = true;
            break;
        }
    }
    return $whitelisted;
}