owncloud/core

<?php
/**
 * @author Björn Schießle <bjoern@schiessle.org>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Roeland Jago Douma <rullzer@owncloud.com>
 * @author Roeland Jago Douma <rullzer@users.noreply.github.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @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/>
 *
 */

namespace OCA\Federation\Controller;

use OCA\Federation\DbHandler;
use OCA\Federation\TrustedServers;
use OCP\AppFramework\Http;
use OCP\AppFramework\OCSController;
use OCP\BackgroundJob\IJobList;
use OCP\ILogger;
use OCP\IRequest;
use OCP\Security\ISecureRandom;

/**
 * Class OCSAuthAPIController
 *
 * OCS API end-points to exchange shared secret between two connected ownClouds
 *
 * @package OCA\Federation\Controller
 */
class OCSAuthAPIController extends OCSController {
    /** @var ISecureRandom  */
    private $secureRandom;

    /** @var IJobList */
    private $jobList;

    /** @var TrustedServers */
    private $trustedServers;

    /** @var DbHandler */
    private $dbHandler;

    /** @var ILogger */
    private $logger;

    /**
     * OCSAuthAPI constructor.
     *
     * @param string $appName
     * @param IRequest $request
     * @param ISecureRandom $secureRandom
     * @param IJobList $jobList
     * @param TrustedServers $trustedServers
     * @param DbHandler $dbHandler
     * @param ILogger $logger
     */
    public function __construct(
        $appName,
        IRequest $request,
        ISecureRandom $secureRandom,
        IJobList $jobList,
        TrustedServers $trustedServers,
        DbHandler $dbHandler,
        ILogger $logger
    ) {
        parent::__construct($appName, $request);

        $this->secureRandom = $secureRandom;
        $this->jobList = $jobList;
        $this->trustedServers = $trustedServers;
        $this->dbHandler = $dbHandler;
        $this->logger = $logger;
    }

    /**
     * @NoCSRFRequired
     * @PublicPage
     *
     * request received to ask remote server for a shared secret
     *
     * @param string $url
     * @param string $token
     * @return array()
     */
    public function requestSharedSecret($url, $token) {
        if ($this->trustedServers->isTrustedServer($url) === false) {
            $this->logger->error('remote server not trusted (' . $url . ') while requesting shared secret', ['app' => 'federation']);
            return ['statuscode' => Http::STATUS_FORBIDDEN];
        }

        // if both server initiated the exchange of the shared secret the greater
        // token wins
        $localToken = $this->dbHandler->getToken($url);
        if (\strcmp($localToken, $token) > 0) {
            $this->logger->info(
                'remote server (' . $url . ') presented lower token. We will initiate the exchange of the shared secret.',
                ['app' => 'federation']
            );
            return ['statuscode' => Http::STATUS_FORBIDDEN];
        }

        // we ask for the shared secret so we no longer have to ask the other server
        // to request the shared secret
        $this->jobList->remove(
            'OCA\Federation\BackgroundJob\RequestSharedSecret',
            [
                'url' => $url,
                'token' => $localToken
            ]
        );

        $this->jobList->add(
            'OCA\Federation\BackgroundJob\GetSharedSecret',
            [
                'url' => $url,
                'token' => $token,
            ]
        );

        return ['statuscode' => Http::STATUS_OK];
    }

    /**
     * @NoCSRFRequired
     * @PublicPage
     *
     * create shared secret and return it
     *
     * @param string $url
     * @param string $token
     * @return array
     */
    public function getSharedSecret($url, $token) {
        if ($this->trustedServers->isTrustedServer($url) === false) {
            $this->logger->error('remote server not trusted (' . $url . ') while getting shared secret', ['app' => 'federation']);
            return ['statuscode' => Http::STATUS_FORBIDDEN];
        }

        if ($this->isValidToken($url, $token) === false) {
            $expectedToken = $this->dbHandler->getToken($url);
            $this->logger->error(
                'remote server (' . $url . ') didn\'t send a valid token (got "' . $token . '" but expected "'. $expectedToken . '") while getting shared secret',
                ['app' => 'federation']
            );
            return ['statuscode' => Http::STATUS_FORBIDDEN];
        }

        $sharedSecret = $this->secureRandom->generate(32);

        $this->trustedServers->addSharedSecret($url, $sharedSecret);
        // reset token after the exchange of the shared secret was successful
        $this->dbHandler->addToken($url, '');

        return ['statuscode' => Http::STATUS_OK,
            'data' => ['sharedSecret' => $sharedSecret]];
    }

    protected function isValidToken($url, $token) {
        $storedToken = $this->dbHandler->getToken($url);
        return \hash_equals($storedToken, $token);
    }
}