Fix possible HTTP DoS on error in keep-alive requests (#1488782)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix possible HTTP DoS on error in keep-alive requests (#1488782)
 - Add option to disable saving sent mail in Sent folder - no_save_sent_messages (#1488686)
 - Fix handling dont_override with message_sort_col and message_sort_order settings (#1488760)
 - Fix HTML part detection in messages with attachments (#1488769)

program/js/app.js

@@ -6273,9 +6273,9 @@ function rcube_webmail()
 
     // re-send keep-alive requests after 30 seconds
     if (action == 'keep-alive')
-      setTimeout(function(){ ref.keep_alive(); }, 30000);
+      setTimeout(function(){ ref.keep_alive(); ref.start_keepalive(); }, 30000);
     else if (action == 'check-recent')
-      setTimeout(function(){ ref.check_for_recent(false); }, 30000);
+      setTimeout(function(){ ref.check_for_recent(false); ref.start_keepalive(); }, 30000);
   };
 
   // post the given form to a hidden iframe