prevent access from origin

<?php
function youShalDie() {
    echo "<h1>YOU SHALL NOT PASS!!</h1>";
    die;
}

if ("GET" == $_SERVER["REQUEST_METHOD"]) {
    if (isset($_SERVER["HTTP_ORIGIN"]) || isset($_SERVER["HTTP_REFERER"])) {
        $allowedOrigin = "https://www.google.com.br/";
        if (
            strpos($allowedOrigin, $_SERVER["HTTP_ORIGIN"]) === FALSE &&
            strpos($allowedOrigin, $_SERVER["HTTP_REFERER"]) === FALSE
        ) {
            youShalDie();
        }
    } else {
        youShalDie();
    }
}

?>