download file php

1.  <?php
2.  $dir="download/";
3.  $filename=$_GET['file'];
4.  $file_path=$dir.$filename;
5.  $ctype="application/octet-stream";
6.  //
7.  if(!empty($file_path) && file_exists($file_path)){ //check keberadaan file
8.    header("Pragma:public");
9.    header("Expired:0");
10.   header("Cache-Control:must-revalidate");
11.   header("Content-Control:public");
12.   header("Content-Description: File Transfer");
13.   header("Content-Type: $ctype");
14.   header("Content-Disposition:attachment; filename=\"".basename($file_path)."\"");
15.   header("Content-Transfer-Encoding:binary");
16.   header("Content-Length:".filesize($file_path));
17.   flush();
18.   readfile($file_path);
19.   exit();
20. }else{
21.   echo "The File does not exist.";
22. }
23. ?>

<?php
if(isset($_REQUEST["file"])){
    // Get parameters
    $file = urldecode($_REQUEST["file"]); // Decode URL-encoded string

    /* Check if the file name includes illegal characters
    like "../" using the regular expression */
    if(preg_match('/^[^.][-a-z0-9_.]+[a-z]$/i', $file)){
        $filepath = "images/" . $file;

        // Process download
        if(file_exists($filepath)) {
            header('Content-Description: File Transfer');
            header('Content-Type: application/octet-stream');
            header('Content-Disposition: attachment; filename="'.basename($filepath).'"');
            header('Expires: 0');
            header('Cache-Control: must-revalidate');
            header('Pragma: public');
            header('Content-Length: ' . filesize($filepath));
            flush(); // Flush system output buffer
            readfile($filepath);
            die();
        } else {
            http_response_code(404);
	        die();
        }
    } else {
        die("Invalid file name!");
    }
}
?>