Protect file downloads with Ultimate Member WordPress plugin

require( dirname( __FILE__ ) . '/wp-blog-header.php' );
global $ultimatemember;
 
// The path to the protected folder relative to the wordpress uploads directory
// e.g. /wp-content/uploads/<$protectedDir>
$protectedDir = 'paid-content';
 
// The required member role (slug of the role)
$requiredRole = 'paidsubscriber';
 
// Map file extensions to mime types (TODO: better implementation?)
$extMap = array(
    'pdf' => 'application/pdf',
    'zip' => 'application/zip'
);
 
// ----- you shouldn't need to modify anything below here -------
 
// Get the user id of the currently logged in user. If no user is logged in, return a 404
$userId = um_profile_id();
if (!$userId) {
    exitWith404();
}
 
// Check the status of the user
um_fetch_user($userId);
$isAdmin = um_user('administrator') === true; // is the user an admin?
$isApproved = um_user('status') === 'approved'; // is the user approved?
$userRole = um_user('role_name'); // the slug of the community role assigned to the user
 
// Check if the user is allowed to access the requested folder
$allow = (($isAdmin === true || $userRole === $requiredRole) && $isApproved === true);
if ($allow !== true) {
    exitWith404();
}
 
// Ensure that the file name provided really and truly exists in the directory we expect
$uploadBase = preg_replace('/[\\/\\\]/', DIRECTORY_SEPARATOR, wp_upload_dir()['basedir']);
$docName = $_GET['f'];
$docPath = realpath(join('/', array($uploadBase, $protectedDir, $docName)));
if (strpos($docPath, $uploadBase) !== 0 || !is_file($docPath)) {
    exitWith404();
}
 
if ($fd = fopen($docPath, "r")) {
    // Try to determine the mime type based on the file extension
    $pathInfo = pathinfo($docPath);
    $ext = strtolower($pathInfo["extension"]);
    if (isset($extMap[$ext])) {
        $contentType = $extMap[$ext];
    }
    else {
        $contentType = 'application/octet-stream'; // TODO: Just a hack fallback
    }
 
    // Set http status to 200 (OK), otherwise it will default to 404
    status_header(200);
    header("Content-type: $contentType");
    header("Content-Disposition: attachment; filename=\"".$pathInfo["basename"]."\"");
    header("Content-Transfer-Encoding: chunked");
    header("Content-length: " . filesize($docPath));
    header("Cache-control: private");
 
    // Output the contents of the file in 2048 byte chunks
    ob_clean();
    flush();
    while (!feof($fd)) {
        echo fread($fd, 2048);
    }
    ob_end_flush();
    fclose ($fd);
    exit;
}
else {
    wp_die('Oops, there was a problem downloading your file. Please try again.');
}
 
/**
* Output the WordPress 404 page
*
*/
function exitWith404() {
    status_header(404);
    nocache_headers();
    include(get_query_template('404'));
    exit;
}