The validity time for NF Instances obtained through NF Discovery was
not properly implemented. Since the validity was 3600 seconds(1 hour),
which caused 5G Core to not work properly after 3600 seconds(1 hour).
There was an issue where an NF Instance should be deleted
when its validity time expired, but it was not working correctly
due to incorrect use of reference count.
Therefore, I have modified the Validity of NF Instances obtained
through NF Discovery to work properly.
I also changed the default value of valdityPeriod to 30 seconds.
This problem can be occurred in the following scenarios.
1. Run NFs(NRF/SCP/SMF/UPF/AUSF/UDM/PCF/BSF/NSSF/UDR) except AMF.
2. Run AMF
3. Run gNB/UE and try to register
4. STOP PCF
5. AMF Crashed
AMF discovered the PCF through SCP during the UE registration process.
At this time, ogs_sbi_nf_fsm_init() is not called,
so AMF does not have state information about PCF.
In other words, AMF state is NULL.
In such a situation, when PCF is terminated at this time,
a crash occurs as AMF attempts to change the PCF state.
So, I've fixed that state information is initialized to solve this problem.
== Known limitation ==
Placing npcf-smpolicycontrol and pcf-policyauthorization
in different NFs is not supported. Both npcf-smpolicycontrol
and pcf-policyauthorization should be placed in the same NF.
Sukchan Lee