/etc != http :)
It'd still leave access to any files in the same (or sub) directory starting with http, which realistically would probably be none but still something to bear in mind.
$url = rawurldecode($_GET['url']);
$url_without_protocol = str_replace(array('https://', 'http://'), '', $url);
$protocol = (stristr($url, 'https://') ? 'https' : 'http');
$page = file_get_contents($protocol . '://' . $url_without_protocol); u = urlparse(url)
if u.scheme not in ['http', 'https']:
return 400