This is the PHP snippet in the generate.php file from the FLIR.

This code will check if the request to generate the FLIR image is allowed or not.

if(false !== ALLOWED_DOMAIN && $_SERVER['HTTP_REFERER'] != '') {
    $refhost = get_hostname($_SERVER['HTTP_REFERER']);
    if(substr(ALLOWED_DOMAIN, 0, 1) == '.') {
        if(false === strpos($refhost, substr(ALLOWED_DOMAIN, 1)))
            err('DISALLOWED_DOMAIN');
    }else {
        if($refhost != ALLOWED_DOMAIN)
            err('DISALLOWED_DOMAIN');
    }
}