<?php
preg_match('/^[a-z0-9_-]+\.txt$/i', $_GET['smp'], $file);

if ( empty($file[0]) ) die();

$str= file_get_contents($file[0]);

header("Content-Type: application/octet-stream;");
	header('Content-Disposition: attachment; filename='.$file[0]);
	header ('Accept-Ranges: bytes');
	header ('Content-Length: '.strlen($str));
	echo $str;
?>