ikev2: Defer path probing if no path is currently available

We do the same before initiating the task, so we should probably do it
too when we already initiated it, not just time out and destroy the SA.

src/libcharon/sa/ikev2/task_manager_v2.c

@@ -120,6 +120,11 @@ struct private_task_manager_t {
 		 */
 		exchange_type_t type;
 
+		/**
+		 * TRUE if exchange was deferred because no path was available
+		 */
+		bool deferred;
+
 	} initiating;
 
 	/**
@@ -289,7 +294,14 @@ METHOD(task_manager_t, retransmit, status_t,
 				DBG1(DBG_IKE, "path probing attempt %d",
 					 this->initiating.retransmitted);
 			}
-			mobike->transmit(mobike, this->initiating.packet);
+			if (!mobike->transmit(mobike, this->initiating.packet))
+			{
+				DBG1(DBG_IKE, "no route found to reach peer, path probing "
+					 "deferred");
+				this->ike_sa->set_condition(this->ike_sa, COND_STALE, TRUE);
+				this->initiating.deferred = TRUE;
+				return SUCCESS;
+			}
 		}
 
 		this->initiating.retransmitted++;
@@ -315,6 +327,12 @@ METHOD(task_manager_t, initiate, status_t,
 		DBG2(DBG_IKE, "delaying task initiation, %N exchange in progress",
 				exchange_type_names, this->initiating.type);
 		/* do not initiate if we already have a message in the air */
+		if (this->initiating.deferred)
+		{	/* re-initiate deferred exchange */
+			this->initiating.deferred = FALSE;
+			this->initiating.retransmitted = 0;
+			return retransmit(this, this->initiating.mid);
+		}
 		return SUCCESS;
 	}
 
@@ -458,6 +476,7 @@ METHOD(task_manager_t, initiate, status_t,
 	message->set_exchange_type(message, exchange);
 	this->initiating.type = exchange;
 	this->initiating.retransmitted = 0;
+	this->initiating.deferred = FALSE;
 
 	enumerator = array_create_enumerator(this->active_tasks);
 	while (enumerator->enumerate(enumerator, &task))