calendarimporter/php/download.php

<?php
/**
 * download.php, Kopano calendar to ics im/exporter
 *
 * Author: Christoph Haas <christoph.h@sprinternet.at>
 * Copyright (C) 2012-2018 Christoph Haas
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
namespace calendarimporter;

class DownloadHandler
{
    /**
     * Download the given vcf file.
     * @return boolean
     */
    public static function doDownload()
    {
        if (isset($_GET["token"])) {
            $token = $_GET["token"];
        } else {
            return false;
        }

        if (isset($_GET["filename"])) {
            $filename = $_GET["filename"];
        } else {
            return false;
        }

        // validate token
        if (!preg_match('/^[a-zA-Z0-9]+$/', $token)) { // token is a md5 hash
            return false;
        }

        $file = PLUGIN_CALENDARIMPORTER_TMP_UPLOAD . "ics_" . $token . ".ics";

        if (!file_exists($file)) { // invalid token
            return false;
        }

        // set headers here
        header('Content-Disposition: attachment; filename="' . $filename . '"');

        // no caching
        header('Expires: 0'); // set expiration time
        header('Content-Description: File Transfer');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        header('Content-Length: ' . filesize($file));
        header('Content-Type: application/octet-stream');
        header('Pragma: public');
        flush();

        // print the downloaded file
        readfile($file);
        ignore_user_abort(true);
        unlink($file);

        return true;
    }
}