Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle 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 General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

namespace mod_bigbluebuttonbn\local\proxy;

use mod_bigbluebuttonbn\extension;

use mod_bigbluebuttonbn\local\config;

use mod_bigbluebuttonbn\local\exceptions\bigbluebutton_exception;

use mod_bigbluebuttonbn\local\exceptions\server_not_available_exception;

use mod_bigbluebuttonbn\plugin;

use moodle_url;

/**

 * The abstract proxy base class.

 *

 * This class provides common and shared functions used when interacting with

 * the BigBlueButton API server.

 *

 * @package   mod_bigbluebuttonbn

 * @copyright 2010 onwards, Blindside Networks Inc

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 * @author    Jesus Federico  (jesus [at] blindsidenetworks [dt] com)

 */

abstract class proxy_base {

    /**

     * Sometimes the server sends back some error and errorKeys that

     * can be converted to Moodle error messages

     */

    const BBB_TO_MOODLE_ERROR_CODE = [

        'checksumError' => 'index_error_checksum',

        'notFound' => 'general_error_not_found',

        'maxConcurrent' => 'view_error_max_concurrent',

    ];

    /**

     * Returns the right URL for the action specified.

     *

     * @param string $action

     * @param array $data

     * @param array $metadata

     * @param int|null $instanceid

     * @return string

     */

    protected static function action_url(

        string $action = '',

        array $data = [],

        array $metadata = [],

        ?int $instanceid = null

    ): string {

        $baseurl = self::sanitized_url() . $action . '?';

        ['data' => $additionaldata, 'metadata' => $additionalmetadata] =

            extension::action_url_addons($action, $data, $metadata, $instanceid);

        $data = array_merge($data, $additionaldata ?? []);

        $metadata = array_merge($metadata, $additionalmetadata ?? []);

        $metadata = array_combine(array_map(function($k) {

            return 'meta_' . $k;

        }, array_keys($metadata)), $metadata);

        $params = http_build_query($data + $metadata, '', '&');

        $checksum = self::get_checksum($action, $params);

        return $baseurl . $params . '&checksum=' . $checksum;

    }

    /**

     * Makes sure the url used doesn't is in the format required.

     *

     * @return string

     */

    protected static function sanitized_url(): string {

        $serverurl = trim(config::get('server_url'));

        if (PHPUNIT_TEST) {

            $serverurl = (new moodle_url(TEST_MOD_BIGBLUEBUTTONBN_MOCK_SERVER))->out(false);

        }

        if (substr($serverurl, -1) == '/') {

            $serverurl = rtrim($serverurl, '/');

        }

        if (substr($serverurl, -4) == '/api') {

            $serverurl = rtrim($serverurl, '/api');

        }

        return $serverurl . '/api/';

    }

    /**

     * Makes sure the shared_secret used doesn't have trailing white characters.

     *

     * @return string

     */

    protected static function sanitized_secret(): string {

        return trim(config::get('shared_secret'));

    }

    /**

     * Throw an exception if there is a problem in the returned XML value

     *

     * @param \SimpleXMLElement|bool $xml

     * @param array|null $additionaldetails

     * @throws bigbluebutton_exception

     * @throws server_not_available_exception

     */

    protected static function assert_returned_xml($xml, ?array $additionaldetails = null): void {

        $messagekey = '';

        if (!empty($xml)) {

            $messagekey = (string) ($xml->messageKey ?? '');

        }

        if (empty($xml) || static::is_known_server_unavailable_errorcode($messagekey)) {

            $errorcode = self::get_errorcode_from_xml_messagekey($messagekey);

            throw new server_not_available_exception(

                $errorcode,

                plugin::COMPONENT,

                (new moodle_url('/admin/settings.php?section=modsettingbigbluebuttonbn'))->out(),

            );

        }

        // If it is a checksum error, this is equivalent to the server not being available.

        // So we treat it the same way as if there is not answer.

        if (is_bool($xml) && $xml) {

            // Nothing to do here, this might be a post returning that everything went well.

            return;

        }

        if ((string) $xml->returncode == 'FAILED') {

            $errorcode = self::get_errorcode_from_xml_messagekey($messagekey);

            if (!$additionaldetails) {

                $additionaldetails = [];

            }

            $additionaldetails['xmlmessage'] = (string) $xml->message ?? '';

            throw new bigbluebutton_exception($errorcode, json_encode($additionaldetails));

        }

    }

    /**

     * Get Moodle error code from returned Message Key

     *

     * @param string $messagekey

     * @return string

     */

    private static function get_errorcode_from_xml_messagekey(string $messagekey): string {

        $errorcode = 'general_error_no_answer';

        if ($messagekey) {

            $errorcode = self::BBB_TO_MOODLE_ERROR_CODE[$messagekey] ?? $errorcode;

        }

        return $errorcode;

    }

    /**

     * Get Moodle error code from returned Message Key

     *

     * @param string $messagekey

     * @return string

     */

    private static function is_known_server_unavailable_errorcode(string $messagekey): string {

        // For now, only checksumError is supposed to mean that the server is unavailable.

        // Other errors are recoverable.

        return in_array($messagekey, ['checksumError']);

    }

    /**

     * Fetch the XML from an endpoint and test for success.

     *

     * If the result could not be loaded, or the returncode was not 'SUCCESS', a null value is returned.

     *

     * @param string $action

     * @param array $data

     * @param array $metadata

     * @param int|null $instanceid

     * @return null|bool|\SimpleXMLElement

     */

    protected static function fetch_endpoint_xml(

        string $action,

        array $data = [],

        array $metadata = [],

        ?int $instanceid = null

    ) {

        if (PHPUNIT_TEST && !defined('TEST_MOD_BIGBLUEBUTTONBN_MOCK_SERVER')) {

            return true; // In case we still use fetch and mock server is not defined, this prevents

            // an error. This can happen if a function from lib.php is called in test from other modules

            // for example.

        }

        $curl = new curl();

        return $curl->get(self::action_url($action, $data, $metadata, $instanceid));

    }

    /**

     * Get checksum

     *

     * @param string $action

     * @param string $params

     * @return string

     */

    public static function get_checksum(string $action, string $params): string {

        return hash(config::get('checksum_algorithm'), $action . $params . self::sanitized_secret());

    }

}