Merge remote-tracking branch 'origin/e1ap-lib-improvements' into integration_2025_w06 (!3219)

E1AP enc/dec lib improvements

This MR is including some fixes and improvements for the E1AP library,
focusing mostly on Bearer Context Management:

- struct reorganization: split setup and modification request messages
  into distinct structures, ensuring compliance with 3GPP TS 38.463
  specifications
- add encoding/decoding sub-functions for different IEs
- improvements to Bearer Context Management: Implemented various
  improvements to the E1 Bearer Context Setup Response and Request,
  including the adoption of encoding/decoding sub-functions for
  different IEs
- use lib functions whenever need (e.g. cp_bearer_context_setup_request
  in cucp_cuup_e1ap.c)
- handle optional struct members as pointers
- updated copy/equality check utility functions

EDIT: The MR is also including the changes from !3222 (closed):

> While testing E1 with security enabled for DRBs, it was found that
> data traffic was not functional.
>
> The problem was that security settings were modified in the PDCP
> reestablishment happening when receiving Bearer Context Modification
> Request.
>
> So some restructuring was done.
>
> The actual fix is in 18176297, the others are for support. Basically
> we introduce a boolean to check if the security settings are present in
> Bearer Context Modification Request and we change PDCP security settings
> only if they are.
>
> (Note that in OAI CU security settings are not sent in Bearer Context
> Modification Request, so we could also remove all this, but we need to
> be compatible with other cu-up and/or cu-cp.)

openair1/SIMULATION/NR_PHY/dlsim.c

@@ -125,7 +125,7 @@ void nr_derive_key_ng_ran_star(uint16_t pci, uint64_t nr_arfcn_dl, const uint8_t
 int dummy_nr_ue_ul_indication(nr_uplink_indication_t *ul_info) { return(0);  }
 
 void e1_bearer_context_setup(const e1ap_bearer_setup_req_t *req) { abort(); }
-void e1_bearer_context_modif(const e1ap_bearer_setup_req_t *req) { abort(); }
+void e1_bearer_context_modif(const e1ap_bearer_mod_req_t *req) { abort(); }
 void e1_bearer_release_cmd(const e1ap_bearer_release_cmd_t *cmd) { abort(); }
 
 int8_t nr_rrc_RA_succeeded(const module_id_t mod_id, const uint8_t gNB_index) {

openair1/SIMULATION/NR_PHY/psbchsim.c

@@ -51,7 +51,7 @@ void e1_bearer_context_setup(const e1ap_bearer_setup_req_t *req)
 {
   abort();
 }
-void e1_bearer_context_modif(const e1ap_bearer_setup_req_t *req)
+void e1_bearer_context_modif(const e1ap_bearer_mod_req_t *req)
 {
   abort();
 }

openair1/SIMULATION/NR_PHY/ulsim.c

@@ -126,7 +126,7 @@ void nr_derive_key_ng_ran_star(uint16_t pci, uint64_t nr_arfcn_dl, const uint8_t
 extern void fix_scd(NR_ServingCellConfig_t *scd);// forward declaration
 
 void e1_bearer_context_setup(const e1ap_bearer_setup_req_t *req) { abort(); }
-void e1_bearer_context_modif(const e1ap_bearer_setup_req_t *req) { abort(); }
+void e1_bearer_context_modif(const e1ap_bearer_mod_req_t *req) { abort(); }
 void e1_bearer_release_cmd(const e1ap_bearer_release_cmd_t *cmd) { abort(); }
 
 int8_t nr_rrc_RA_succeeded(const module_id_t mod_id, const uint8_t gNB_index) {