Add intermediate fallback to rrc_gNB_get_ue_context_by_rnti_any_du() in
re-establishment request handling to better handle cases where UE
re-establishes on a different DU.
RNTI is NOT globally unique - different DUs can assign the same RNTI to
different UEs. The assoc_id check in rrc_gNB_get_ue_context_by_rnti()
disambiguates RNTI across DUs and prevents returning the wrong UE.
However, during re-establishment on a different DU, du_assoc_id hasn't
been updated yet (message comes from new DU, but ue_data.du_assoc_id
still points to old DU), causing the primary lookup to fail even though
the UE exists.
The lookup now uses a three-tier fallback:
1. Primary: rrc_gNB_get_ue_context_by_rnti() with assoc_id check
(normal case: same DU)
2. Fallback 1: rrc_gNB_get_ue_context_by_rnti_any_du() by RNTI only
(re-establishment on different DU)
3. Fallback 2: rrc_gNB_get_ue_context_source_cell() using physCellId
(handover scenarios)
Guido Casati
9a11690f81