<?php
$url = isset($_GET['url']) && filter_var($_GET['url'], FILTER_VALIDATE_URL) ? $_GET['url'] : '';
?>
<iframe src="<?php echo $url ?>"></iframe>

<iframe id="frame"></iframe>
<script>
var urlParams = new URLSearchParams(window.location.search);
var url = urlParams.get('url');
if(!url.match(/(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/g)) {
	url = '';
}
document.getElementById('frame').src = url;
</script>