ike-mobike: Always use this task for DPDs even if not behind a NAT

This allows switching to probing mode if the client is on a public IP
and this is the active task and connectivity gets restored.  We only add
NAT-D payloads if we are currently behind a NAT (to detect changed NAT
mappings), a MOBIKE update that might follow will add them in case we
move behind a NAT.

src/libcharon/sa/ikev2/task_manager_v2.c

@@ -1946,8 +1946,7 @@ METHOD(task_manager_t, queue_dpd, void,
 {
 	ike_mobike_t *mobike;
 
-	if (this->ike_sa->supports_extension(this->ike_sa, EXT_MOBIKE) &&
-		this->ike_sa->has_condition(this->ike_sa, COND_NAT_HERE))
+	if (this->ike_sa->supports_extension(this->ike_sa, EXT_MOBIKE))
 	{
 #ifdef ME
 		peer_cfg_t *cfg = this->ike_sa->get_peer_cfg(this->ike_sa);

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

@@ -193,7 +193,7 @@ static void process_payloads(private_ike_mobike_t *this, message_t *message)
 			case NAT_DETECTION_DESTINATION_IP:
 			{
 				/* NAT check in this MOBIKE exchange, create subtask for it */
-				if (this->natd == NULL)
+				if (!this->natd)
 				{
 					this->natd = ike_natd_create(this->ike_sa, this->initiator);
 				}
@@ -648,7 +648,7 @@ METHOD(ike_mobike_t, roam, void,
 METHOD(ike_mobike_t, dpd, void,
 	   private_ike_mobike_t *this)
 {
-	if (!this->natd)
+	if (!this->natd && this->ike_sa->has_condition(this->ike_sa, COND_NAT_HERE))
 	{
 		this->natd = ike_natd_create(this->ike_sa, this->initiator);
 	}