MDL-80835 auth_lti: add partitioning to post-auth MoodleSession cookie

Adds the property that is required by Chrome to opt-in to its 3rd party
cookie partitioning solution, CHIPS. This specific change to auth_lti is
to ensure the MoodleSession Set-Cookie header resulting from
complete_user_login() calls (in auth.php) have this property set.

auth/lti/classes/local/ltiadvantage/event/event_handler.php

@@ -0,0 +1,50 @@
+<?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 auth_lti\local\ltiadvantage\event;
+
+use auth_lti\local\ltiadvantage\utility\cookie_helper;
+use core\event\user_loggedin;
+
+/**
+ * Event handler for auth_lti.
+ *
+ * @package    auth_lti
+ * @copyright  2024 Jake Dallimore <[email protected]>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class event_handler {
+
+    /**
+     * Allows the plugin to augment Set-Cookie headers when the user_loggedin event is fired as part of complete_user_login() calls.
+     *
+     * @param user_loggedin $event the event
+     * @return void
+     */
+    public static function handle_user_loggedin(user_loggedin $event): void {
+        // The event data isn't important here. The intent of this listener is to ensure that the MoodleSession cookie gets the
+        // 'Partitioned' attribute, when required - an opt-in flag needed to use Chrome's partitioning mechanism, CHIPS. During LTI
+        // auth, the auth class (auth/lti/auth.php) calls complete_user_login(), which generates a new session cookie as part of its
+        // login process. This handler makes sure that this new cookie is intercepted and partitioned, if needed.
+        if (cookie_helper::cookies_supported()) {
+            if (cookie_helper::get_cookies_supported_method() == cookie_helper::COOKIE_METHOD_EXPLICIT_PARTITIONING) {
+                global $CFG;
+                cookie_helper::add_attributes_to_cookie_response_header('MoodleSession' . $CFG->sessioncookie,
+                    ['Partitioned', 'Secure']);
+            }
+        }
+    }
+}

auth/lti/db/events.php

@@ -0,0 +1,33 @@
+<?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/>.
+
+/**
+ * LTI Auth plugin event handler definition.
+ *
+ * @package auth_lti
+ * @category event
+ * @copyright 2024 Jake Dallimore <[email protected]>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$observers = [
+    [
+        'eventname' => '\core\event\user_loggedin',
+        'callback' => '\auth_lti\local\ltiadvantage\event\event_handler::handle_user_loggedin',
+    ],
+];

auth/lti/version.php

@@ -24,6 +24,6 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version = 2023100900; // The current plugin version (Date: YYYYMMDDXX).
+$plugin->version = 2024020700; // The current plugin version (Date: YYYYMMDDXX).
 $plugin->requires = 2023100400; // Requires this Moodle version.
 $plugin->component = 'auth_lti'; // Full name of the plugin (used for diagnostics).