nextcloud-server/apps/user_webdavauth/settings.php

<?php
/**
 * @author Bart Visscher <bartv@thisnet.nl>
 * @author Frank Karlitschek <frank@owncloud.org>
 * @author Lukas Reschke <lukas@owncloud.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @copyright Copyright (c) 2015, ownCloud, Inc.
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

OC_Util::checkAdminUser();

if($_POST) {
	// CSRF check
	OCP\JSON::callCheck();

	if(isset($_POST['webdav_url'])) {
		OC_CONFIG::setValue('user_webdavauth_url', strip_tags($_POST['webdav_url']));
	}
}

// fill template
$tmpl = new OC_Template( 'user_webdavauth', 'settings');
$tmpl->assign( 'webdav_url', OC_Config::getValue( "user_webdavauth_url" ));

return $tmpl->fetchPage();