Merge remote-tracking branch 'origin/fix-bug-release-no-amf' into integration_2026_w03 (!3857)

Fix bug "no AMF for UE"

It might happen that the RRC does not know the AMF UE NGAP ID, yet. Even
in that case, we should forward the release request to the NGAP module,
which can either forward a message to the AMF, or reply back to release
the UE. This avoids an error where the CU claims there was no AMF, when
there actually is.

One possible problematic behavior is if a UE disconnects before the gNB
receives an NGAP Initial Context Setup. In this case, the AMF UE NGAP ID
was not forwarded to the RRC (although it was known at NGAP), thus
blocking the release of the UE.

This is the main fix, the rest are minor fixes:

- store AMF UE NGAP ID as early as possible
- warn in MAC if UE unknown for UE context release command
- show TEIDs with correct endianness in GTP
- avoid NG Setup Failure+Setup log.

openair2/RRC/NR/rrc_gNB.c

@@ -2440,10 +2440,8 @@ static void rrc_CU_process_ue_context_release_request(MessageDef *msg_p, sctp_as
   gNB_RRC_INST *rrc = RC.nrrrc[instance];
   rrc_gNB_ue_context_t *ue_context_p = rrc_gNB_get_ue_context(rrc, req->gNB_CU_ue_id);
   int srbid = 1;
-  // valid AMF UE NGAP ID range is 0..2^40-1
-  if (!ue_context_p || ue_context_p->ue_context.amf_ue_ngap_id >= (1LL << 40)) {
-    const char *reason = !ue_context_p ? "could not find UE context" : "no AMF";
-    LOG_W(RRC, "%s for CU UE ID %u: auto-generate release command\n", reason, req->gNB_CU_ue_id);
+  if (!ue_context_p) {
+    LOG_W(RRC, "could not find UE context for CU UE ID %u: auto-generate release command\n", req->gNB_CU_ue_id);
     uint8_t buffer[NR_RRC_BUF_SIZE] = {0};
     int size = do_NR_RRCRelease(buffer, NR_RRC_BUF_SIZE, rrc_gNB_get_next_transaction_identifier(0));
     RETURN_IF_INVALID_ASSOC_ID(assoc_id);

openair2/RRC/NR/rrc_gNB_NGAP.c

@@ -717,6 +717,7 @@ int rrc_gNB_process_NGAP_DOWNLINK_NAS(MessageDef *msg_p, instance_t instance, mu
   }
 
   gNB_RRC_UE_t *UE = &ue_context_p->ue_context;
+  UE->amf_ue_ngap_id = req->amf_ue_ngap_id;
   UE->nas_pdu = req->nas_pdu;
   rrc_forward_ue_nas_message(rrc, UE);
   return 0;