$forumid = required_param('forumid', PARAM_INT); // The forum to subscribe or unsubscribe.
$discussionid = optional_param('discussionid', null, PARAM_INT); // The discussionid to subscribe.
-$sesskey = optional_param('sesskey', null, PARAM_RAW);
$includetext = optional_param('includetext', false, PARAM_BOOL);
$forum = $DB->get_record('forum', array('id' => $forumid), '*', MUST_EXIST);
$cm = get_coursemodule_from_instance('forum', $forum->id, $course->id, false, MUST_EXIST);
$context = context_module::instance($cm->id);
+require_sesskey();
require_login($course, false, $cm);
require_capability('mod/forum:viewdiscussion', $context);