ike: Delay actively initiated reauthentication when other exchanges in progress

If any other IKE or CHILD_SA operation takes places, we should not start
initiating reauthentication to avoid any potential races.

src/libcharon/processing/jobs/rekey_ike_sa_job.c

@@ -46,11 +46,47 @@ METHOD(job_t, destroy, void,
 	free(this);
 }
 
+/**
+ * Check if we should delay a reauth, and by how many seconds
+ */
+static u_int32_t get_retry_delay(ike_sa_t *ike_sa)
+{
+	enumerator_t *enumerator;
+	child_sa_t *child_sa;
+	u_int32_t retry = 0;
+
+	/* avoid reauth collisions for certain IKE_SA/CHILD_SA states */
+	if (ike_sa->get_state(ike_sa) != IKE_ESTABLISHED)
+	{
+		retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
+		DBG1(DBG_IKE, "unable to reauthenticate in %N state, delaying for %us",
+			 ike_sa_state_names, ike_sa->get_state(ike_sa), retry);
+	}
+	else
+	{
+		enumerator = ike_sa->create_child_sa_enumerator(ike_sa);
+		while (enumerator->enumerate(enumerator, &child_sa))
+		{
+			if (child_sa->get_state(child_sa) != CHILD_INSTALLED)
+			{
+				retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
+				DBG1(DBG_IKE, "unable to reauthenticate in CHILD_SA %N state, "
+					 "delaying for %us", child_sa_state_names,
+					 child_sa->get_state(child_sa), retry);
+				break;
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	return retry;
+}
+
 METHOD(job_t, execute, job_requeue_t,
 	private_rekey_ike_sa_job_t *this)
 {
 	ike_sa_t *ike_sa;
 	status_t status = SUCCESS;
+	u_int32_t retry = 0;
 
 	ike_sa = charon->ike_sa_manager->checkout(charon->ike_sa_manager,
 											  this->ike_sa_id);
@@ -62,7 +98,11 @@ METHOD(job_t, execute, job_requeue_t,
 	{
 		if (this->reauth)
 		{
-			status = ike_sa->reauth(ike_sa);
+			retry = get_retry_delay(ike_sa);
+			if (!retry)
+			{
+				status = ike_sa->reauth(ike_sa);
+			}
 		}
 		else
 		{
@@ -71,13 +111,18 @@ METHOD(job_t, execute, job_requeue_t,
 
 		if (status == DESTROY_ME)
 		{
-			charon->ike_sa_manager->checkin_and_destroy(charon->ike_sa_manager, ike_sa);
+			charon->ike_sa_manager->checkin_and_destroy(charon->ike_sa_manager,
+														ike_sa);
 		}
 		else
 		{
 			charon->ike_sa_manager->checkin(charon->ike_sa_manager, ike_sa);
 		}
 	}
+	if (retry)
+	{
+		return JOB_RESCHEDULE(retry);
+	}
 	return JOB_REQUEUE_NONE;
 }