确保URL来自同一服务器[重复]

Maybe I don't know how to phrase my searches properly, but this is what I need to do: Make sure that when a user clicks on my ad, it only comes from one particular site, otherwise returns false, or error.

FILTER_VALIDATE_URL

This only makes sure the URL is valid; I want to make sure it only originates from www.example.com or example.com, etc., but from nowhere else.

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You can simply use $_SERVER['HTTP_REFERER'] then use PHP's parse_url function and use a condition for your url

ex:

$url = $_SERVER['HTTP_REFERER'];

if ( $parts = parse_url($url ) ) {
    $host = $parts[ "host" ];
if($host == 'www.example.com' || $host == 'example.com'){
  //... your action
}

}

reference: Extract Scheme and Host from HTTP_REFERER