ikev2: Add possibility to delay initiation of a queued task

Such a task is not initiated unless a certain time has passed.  This
allows delaying certain tasks but avoids problems if we'd do this
via a scheduled job (e.g. if the IKE_SA is rekeyed in the meantime).

If the IKE_SA is rekeyed the delay of such tasks is reset when the
tasks are adopted i.e. they get executed immediately on the new IKE_SA.

This hasn't been implemented for IKEv1 yet.

src/libcharon/sa/ike_sa.h

@@ -1,9 +1,9 @@
 /*
- * Copyright (C) 2006-2015 Tobias Brunner
+ * Copyright (C) 2006-2016 Tobias Brunner
  * Copyright (C) 2006 Daniel Roethlisberger
  * Copyright (C) 2005-2009 Martin Willi
  * Copyright (C) 2005 Jan Hutter
- * Hochschule fuer Technik Rapperswil
+ * HSR Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -1123,6 +1123,15 @@ struct ike_sa_t {
 	 */
 	void (*queue_task)(ike_sa_t *this, task_t *task);
 
+	/**
+	 * Queue a task in the manager, but delay its initiation for at least the
+	 * given number of seconds.
+	 *
+	 * @param task			task to queue
+	 * @param delay			minimum delay in s before initiating the task
+	 */
+	void (*queue_task_delayed)(ike_sa_t *this, task_t *task, uint32_t delay);
+
 	/**
 	 * Inherit required attributes to new SA before rekeying.
 	 *