Hide media files for non-logged-in users in WordPress

dl-file.php

<?php //Credits: http://0to5.com/protecting-wordpress-media-uploads-unless-user-is-logged-in/

require_once('wp-load.php');
If (!is_user_logged_in()){
$upload_dir = wp_upload_dir();
echo $upload_dir['baseurl'] . '/' . $_GET[ 'file' ];
wp_redirect( wp_login_url( $upload_dir['baseurl'] . '/' . $_GET[ 'file' ]));
exit();
}
list($basedir) = array_values(array_intersect_key(wp_upload_dir(), array('basedir' => 1)))+array(NULL);
$file = rtrim($basedir,'/').'/'.str_replace('..', '', isset($_GET[ 'file' ])?$_GET[ 'file' ]:'');
if (!$basedir || !is_file($file)) {
status_header(404);
die('404 — File not found.');
}
$mime = wp_check_filetype($file);
if( false === $mime[ 'type' ] && function_exists( 'mime_content_type' ) )
$mime[ 'type' ] = mime_content_type( $file );
if( $mime[ 'type' ] )
$mimetype = $mime[ 'type' ];
else
$mimetype = 'image/' . substr( $file, strrpos( $file, '.' ) + 1 );
header( 'Content-Type: ' . $mimetype ); // always send this
if ( false === strpos( $_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS' ) )
header( 'Content-Length: ' . filesize( $file ) );
$last_modified = gmdate( 'D, d M Y H:i:s', filemtime( $file ) );
$etag = '"' . md5( $last_modified ) . '"';
header( "Last-Modified: $last_modified GMT" );
header( 'ETag: ' . $etag );
header( 'Expires: ' . gmdate( 'D, d M Y H:i:s', time() + 100000000 ) . ' GMT' );
// Support for Conditional GET
$client_etag = isset( $_SERVER['HTTP_IF_NONE_MATCH'] ) ? stripslashes( $_SERVER['HTTP_IF_NONE_MATCH'] ) : false;
if( ! isset( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) )
$_SERVER['HTTP_IF_MODIFIED_SINCE'] = false;
$client_last_modified = trim( $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
// If string is empty, return 0. If not, attempt to parse into a timestamp
$client_modified_timestamp = $client_last_modified ? strtotime( $client_last_modified ) : 0;
// Make a timestamp for our most recent modification...
$modified_timestamp = strtotime($last_modified);
if ( ( $client_last_modified && $client_etag )
? ( ( $client_modified_timestamp >= $modified_timestamp) && ( $client_etag == $etag ) )
: ( ( $client_modified_timestamp >= $modified_timestamp) || ( $client_etag == $etag ) )
) {
status_header( 304 );
exit;
}
// If we made it this far, just serve the file
readfile( $file );

?>

htaccess

RewriteCond %{REQUEST_FILENAME} -s
RewriteRule ^wp-content/uploads/(.*)$ dl-file.php?file=$1 [QSA,L]