MDL-70128 webservice: New entry point for draftfiles

webservice/draftfile.php

+<?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/>.
+
+
+/**
+ * Entry point for web service via tokens access to draftfile.php.
+ *
+ * @package    core
+ * @copyright  2020 Juan Leyva <juan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+/**
+ * AJAX_SCRIPT - exception will be converted into JSON.
+ */
+define('AJAX_SCRIPT', true);
+
+/**
+ * NO_MOODLE_COOKIES - we don't want any cookie.
+ */
+define('NO_MOODLE_COOKIES', true);
+
+require_once(__DIR__ . '/../config.php');
+require_once($CFG->dirroot . '/webservice/lib.php');
+
+// Allow CORS requests.
+header('Access-Control-Allow-Origin: *');
+
+// Authenticate the user.
+$token = required_param('token', PARAM_ALPHANUM);
+
+$webservicelib = new webservice();
+$authenticationinfo = $webservicelib->authenticate_user($token);
+
+// Check the service allows file download.
+if (empty($authenticationinfo['service']->downloadfiles)) {
+    throw new webservice_access_exception('Web service file downloading must be enabled in external service settings.');
+}
+
+require_once($CFG->dirroot . '/draftfile.php');