View file download.php

<?php
/* code by DQH - DDVIET.VN */
define('IN_DDU',1);
require_once('common.php');
$idf = intval($_GET['id_file']);
$au = intval($_GET['author']);
if(!isset($_SESSION['download'.$idf])) go(URL.'/viewfile.php?id='.$idf);

$queryFile = mysql_query("select name,size from files where id = '$idf'");
if($_GET['code'] != $_SESSION['download'.$idf]) go(URL.'/viewfile.php?id='.$idf);
elseif(mysql_num_rows($queryFile)>0){
    $info = mysql_fetch_assoc($queryFile);
    mysql_free_result($queryFile);
    $filed = 'data/ID'.$au.'/'.$info['name'];
    if(!is_file($filed) || !is_readable($filed)) {
        go(URL.'/viewfile.php?id=0');
    } else {
        mysql_query("UPDATE files SET downloaded = downloaded+1 WHERE id = '$idf'");
        $fp=fopen($filed, "rb");
        header('Content-type:application/octet-stream');
        header('Content-disposition: attachment;filename="'.$info['name'].'"');
        header('Content-length: '.$info['size']);
        fpassthru($fp);
        fclose($fp);
    }
} else go(URL.'/viewfile.php?id=0');
?>