bus: Add a handle_vips() hook invoked after handling configuration attributes

Similar to assign_vips() used by a peer assigning virtual IPs to the other peer,
the handle_vips() hook gets invoked on a peers after receiving attributes. On
release of the same attributes the hook gets invoked again.

This is useful to inspect handled attributes, as the ike_updown() hook is
invoked after authentication, when attributes have not been handled yet.

src/libcharon/sa/ikev2/tasks/ike_config.c

@@ -446,6 +446,8 @@ METHOD(task_t, process_i, status_t,
 			}
 		}
 		enumerator->destroy(enumerator);
+
+		charon->bus->handle_vips(charon->bus, this->ike_sa, TRUE);
 		return SUCCESS;
 	}
 	return NEED_MORE;