PHP - Valid IP and CIDR

check.php

<?php

    function valid_ip_or_cidr($input)
    {
        if (is_int(strpos($value, '/')))
        {
            /*
             * https://www.regexpal.com/93987
             * if ip_cidr valid return 1, else 0
             */
            $valid = preg_match('/^([0-9]{1,3}\.){3}[0-9]{1,3}(\/([0-9]|[1-2][0-9]|3[0-2]))?$/', $input);
        } else
        {
            // if ip valid return ip, else FALSE
            $valid = filter_var($input, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
        }
      
        return (boolean)$valid;
    }