server/core/ajax/appconfig.php

<?php
/**
 * @author Lukas Reschke <lukas@owncloud.com>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @copyright Copyright (c) 2016, 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();
OCP\JSON::callCheck();

$action=isset($_POST['action'])?$_POST['action']:$_GET['action'];

if(isset($_POST['app']) || isset($_GET['app'])) {
	$app=OC_App::cleanAppId(isset($_POST['app'])? (string)$_POST['app']: (string)$_GET['app']);
}

// An admin should not be able to add remote and public services
// on its own. This should only be possible programmatically.
// This change is due the fact that an admin may not be expected 
// to execute arbitrary code in every environment.
if($app === 'core' && isset($_POST['key']) &&(substr((string)$_POST['key'],0,7) === 'remote_' || substr((string)$_POST['key'],0,7) === 'public_')) {
	OC_JSON::error(array('data' => array('message' => 'Unexpected error!')));
	return;
}

$result=false;
$appConfig = \OC::$server->getAppConfig();
switch($action) {
	case 'getValue':
		$result=$appConfig->getValue($app, (string)$_GET['key'], (string)$_GET['defaultValue']);
		break;
	case 'setValue':
		$result=$appConfig->setValue($app, (string)$_POST['key'], (string)$_POST['value']);
		break;
	case 'getApps':
		$result=$appConfig->getApps();
		break;
	case 'getKeys':
		$result=$appConfig->getKeys($app);
		break;
	case 'hasKey':
		$result=$appConfig->hasKey($app, (string)$_GET['key']);
		break;
	case 'deleteKey':
		$result=$appConfig->deleteKey($app, (string)$_POST['key']);
		break;
	case 'deleteApp':
		$result=$appConfig->deleteApp($app);
		break;
}
OC_JSON::success(array('data'=>$result));