fix: issue 911 - replace timer oneshot to periodic.

Updated SCTP reconnect timer from TIMER_ONE_SHOT to
TIMER_PERIODIC so gNB continuously retries AMF lookup every
30 seconds after disconnect.

Timer is now removed only when ngap_amf_associated_nb > 0,
AMF association is actually back.

openair3/NGAP/ngap_gNB_handlers.c

@@ -68,9 +68,17 @@ void ngap_handle_ng_setup_message(ngap_gNB_amf_data_t *amf_desc_p, int sctp_shut
       }
     }
   } else {
+    if (amf_desc_p->t_reconnect != -1 && amf_desc_p->ngap_gNB_instance->ngap_amf_associated_nb > 0) {
+      timer_remove(amf_desc_p->t_reconnect);
+      amf_desc_p->t_reconnect = -1;
+      NGAP_INFO("reconnected to AMF\n");
+    }
+
     /* Check that at least one setup message is pending */
-    DevCheck(amf_desc_p->ngap_gNB_instance->ngap_amf_pending_nb > 0, amf_desc_p->ngap_gNB_instance->instance,
-             amf_desc_p->ngap_gNB_instance->ngap_amf_pending_nb, 0);
+    DevCheck(amf_desc_p->ngap_gNB_instance->ngap_amf_pending_nb > 0,
+             amf_desc_p->ngap_gNB_instance->instance,
+             amf_desc_p->ngap_gNB_instance->ngap_amf_pending_nb,
+             0);
 
     if (amf_desc_p->ngap_gNB_instance->ngap_amf_pending_nb > 0) {
       /* Decrease pending messages number */

openair3/NGAP/ngap_gNB_ue_context.c

@@ -94,7 +94,7 @@ void ngap_release_ues_for_amf(ngap_gNB_amf_data_t *amf_desc_p)
                        0,
                        TASK_NGAP,
                        amf_desc_p->ngap_gNB_instance->instance,
-                       TIMER_ONE_SHOT,
+                       TIMER_PERIODIC,
                        amf_desc_p,
                        &tid);
   if (rc == 0) {