PHP禁止从其他站点访问

Question

How can i make this file to redirect or to block if visited from another site.

example i want to allow this script to be accessed just from my site example.com and if any other site try to access this php file can it be blocked or redirect

<?php
if (isset($_GET['id'])) {
if (isset($_SERVER['HTTP_RANGE']) && !empty($_SERVER['HTTP_RANGE'])) {


    require_once './include/db.php';
    require_once './include/video-stream.php';
    $stm = $db->prepare("select * from video where code=?");
    $stm->execute(array($_GET['id']));

    if ($stm->rowCount() > 0) {

        $row = $stm->fetch();


        $stream = new VideoStream($row->path);
        $stream->start();
    } else {
        header("message1");
        echo "message2";
        die();
    }
}

Answer 1

Create a .htaccess file in that directory where the file resides and add

<Files "*">
 Order deny, allow
 Deny from all
 Allow from .example.com
</Files>

which will block that directory accessing from other sites