PMPro protect (lock) download non wordpress file

<?php
/*
Plugin Name: PMPro Customizations
Plugin URI: http://www.paidmembershipspro.com/wp/pmpro-customizations/
Description: Customizations for Paid Memberships Pro
Version: 0.1
Author: You
Author URI: https://facebook.com/You
*/
// NOTE: Copy this code and paste it at: wp-content/plugins/pmpro-customizations/pmpro-customizations.php
//       You can add more modification here
/* PMPro Protect Download */
function my_pmpro_getfile()
{
    if(isset($_REQUEST['pmpro_getfile']))
    {
        global $wpdb;

        //prevent loops when redirecting to .php files
        if(!empty($_REQUEST['noloop']))
        {
            status_header( 500 );
            die("This file cannot be loaded through the get file script.");
        }

        $uri = $_REQUEST['pmpro_getfile'];
        if($uri[0] == "/")
            $uri = substr($uri, 1, strlen($uri) - 1);

        /*
        Remove ../-like strings from the URI.
        Actually removes any combination of two or more ., /, and \.
        This will prevent traversal attacks and loading hidden files.
        */
        $uri = preg_replace("/[\.\/\\\\]{2,}/", "", $uri);

        //edit to point at your protected directory
        $new_uri = "downloads/" . $uri;

        $filename = ABSPATH . $new_uri;
        $pathParts = pathinfo($filename);

        //remove params from the end
        if(strpos($filename, "?") !== false)
        {
            $parts = explode("?", $filename);
            $filename = $parts[0];
        }

        //add index.html if this is a directory
        if(is_dir($filename))
            $filename .= "index.html";

        //only checking if the file is pulled from outside the admin
        if(!is_admin())
        {
            //non-members don't have access (checks for level 2 or 3)
            if(!pmpro_hasMembershipLevel())
            {
                //nope
                //header('HTTP/1.1 503 Service Unavailable', true, 503);
                //echo "HTTP/1.1 503 Service Unavailable";
                wp_redirect(wp_login_url());
                exit;
            }
        }

        //if file is not found, die
        if(!file_exists($filename))
        {
            status_header( 404 );
                nocache_headers();
                die("File not found.");
        }

        //if blacklistsed file type, redirect to it instead
        $basename = basename($filename);
        $parts = explode('.', $basename);
        $ext = strtolower($parts[count($parts)-1]);

        //build blacklist and allow for filtering
        $blacklist = array("inc", "php", "php3", "php4", "php5", "phps", "phtml");
        $blacklist = apply_filters("pmpro_getfile_extension_blacklist", $blacklist);

        //check
        if(in_array($ext, $blacklist))
        {
            //add a noloop param to avoid infinite loops
            $uri = add_query_arg("noloop", 1, $uri);

            //guess scheme and add host back to uri
            if(is_ssl())
                $uri = "https://" . $_SERVER['HTTP_HOST'] . "/" . $uri;
            else
                $uri = "http://" . $_SERVER['HTTP_HOST'] . "/" . $uri;

            wp_redirect($uri);
            exit;
        }

        require_once(dirname(__FILE__) . '/../paid-memberships-pro/classes/class.mimetype.php');

        //otherwise show it
        $mimetype = new pmpro_mimetype();
        header("Content-type: " . $mimetype->getType($filename));
        header("Content-Disposition: attachment; filename=" . basename($filename) . ";"); /*make sure download file name not random*/
        readfile($filename);
        exit;
    }
}
add_action("init", "my_pmpro_getfile");
?>