Adds a field starttime in the session. It permits to detect if the session has expired

main/inc/lib/main_api.lib.php

@@ -996,7 +996,6 @@ function api_get_course_info($course_code = null) {
 function api_session_start($already_installed = true) {
 	global $storeSessionInDb;
 	global $_configuration;
-
 	/* causes too many problems and is not configurable dynamically
 	   if($already_installed){
 	   $session_lifetime = 360000;
@@ -1018,6 +1017,9 @@ function api_session_start($already_installed = true) {
 	}
 	session_name('dk_sid');
 	session_start();
+	if (!isset($_SESSION['starttime'])) {
+		$_SESSION['starttime'] = time();
+	}
 	if ($already_installed) {
 		if (empty ($_SESSION['checkDokeosURL'])) {
 			$_SESSION['checkDokeosURL'] = api_get_path(WEB_PATH);