From 34b5e592f0e10cf72df4dd6484da9acf60734d5f Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@openairinterface.org>
Date: Fri, 19 Jan 2024 16:42:05 +0100
Subject: [PATCH] Add function to activate SRBs in gNB RRC

Create a single function to activate an SRB. This function derives the
corresponding keys, triggers the setup in PDCP, and marks the SRB as set
up, instead of doing all of this common functionality in individual
steps.  Use it at the corresponding places.
---
 openair2/RRC/NR/rrc_gNB.c | 53 ++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 17 deletions(-)

diff --git a/openair2/RRC/NR/rrc_gNB.c b/openair2/RRC/NR/rrc_gNB.c
index 3c84737db6..46db206991 100644
--- a/openair2/RRC/NR/rrc_gNB.c
+++ b/openair2/RRC/NR/rrc_gNB.c
@@ -442,6 +442,38 @@ static void freeSRBlist(NR_SRB_ToAddModList_t *l)
     LOG_E(NR_RRC, "Call free SRB list on NULL pointer\n");
 }
 
+static void activate_srb(gNB_RRC_UE_t *UE, int srb_id)
+{
+  AssertFatal(srb_id == 1 || srb_id == 2, "handling only SRB 1 or 2\n");
+  if (UE->Srb[srb_id].Active == 1) {
+    LOG_W(RRC, "UE %d SRB %d already activated\n", UE->rrc_ue_id, srb_id);
+    return;
+  }
+  LOG_I(RRC, "activate SRB %d of UE %d\n", srb_id, UE->rrc_ue_id);
+  UE->Srb[srb_id].Active = 1;
+
+  NR_SRB_ToAddModList_t *list = CALLOC(sizeof(*list), 1);
+  asn1cSequenceAdd(list->list, NR_SRB_ToAddMod_t, srb);
+  srb->srb_Identity = srb_id;
+
+  if (srb_id == 1) {
+    nr_pdcp_add_srbs(true, UE->rrc_ue_id, list, 0, NULL, NULL);
+  } else {
+    uint8_t kRRCenc[16] = {0};
+    uint8_t kRRCint[16] = {0};
+    nr_derive_key(RRC_ENC_ALG, UE->ciphering_algorithm, UE->kgnb, kRRCenc);
+    nr_derive_key(RRC_INT_ALG, UE->integrity_algorithm, UE->kgnb, kRRCint);
+
+    nr_pdcp_add_srbs(true,
+                     UE->rrc_ue_id,
+                     list,
+                     (UE->integrity_algorithm << 4) | UE->ciphering_algorithm,
+                     kRRCenc,
+                     kRRCint);
+  }
+  freeSRBlist(list);
+}
+
 //-----------------------------------------------------------------------------
 static void rrc_gNB_generate_RRCSetup(instance_t instance,
                                       rnti_t rnti,
@@ -463,12 +495,7 @@ static void rrc_gNB_generate_RRCSetup(instance_t instance,
   AssertFatal(size > 0, "do_RRCSetup failed\n");
   AssertFatal(size <= 1024, "memory corruption\n");
 
-  LOG_DUMPMSG(NR_RRC, DEBUG_RRC,
-              (char *)buf,
-              size,
-              "[MSG] RRC Setup\n");
-  nr_pdcp_add_srbs(true, ue_p->rrc_ue_id, SRBs, 0, NULL, NULL);
-
+  LOG_DUMPMSG(NR_RRC, DEBUG_RRC, (char *)buf, size, "[MSG] RRC Setup\n");
   freeSRBlist(SRBs);
   f1_ue_data_t ue_data = cu_get_f1_ue_data(ue_p->rrc_ue_id);
   RETURN_IF_INVALID_ASSOC_ID(ue_data);
@@ -944,14 +971,6 @@ static void rrc_gNB_process_RRCReconfigurationComplete(const protocol_ctxt_t *co
   LOG_D(NR_RRC, "Configuring PDCP DRBs/SRBs for UE %04x\n", ue_p->rnti);
   ue_context_pP->ue_context.ue_reconfiguration_after_reestablishment_counter++;
 
-  NR_SRB_ToAddModList_t *SRBs = createSRBlist(ue_p, false);
-  nr_pdcp_add_srbs(ctxt_pP->enb_flag,
-                   ue_p->rrc_ue_id,
-                   SRBs,
-                   (ue_p->integrity_algorithm << 4) | ue_p->ciphering_algorithm,
-                   kRRCenc,
-                   kRRCint);
-  freeSRBlist(SRBs);
   nr_pdcp_add_drbs(ctxt_pP->enb_flag,
                    ue_p->rrc_ue_id,
                    DRB_configList,
@@ -1235,7 +1254,7 @@ static void rrc_handle_RRCSetupRequest(gNB_RRC_INST *rrc, sctp_assoc_t assoc_id,
   gNB_RRC_UE_t *UE = &ue_context_p->ue_context;
   UE = &ue_context_p->ue_context;
   UE->establishment_cause = rrcSetupRequest->establishmentCause;
-  UE->Srb[1].Active = 1;
+  activate_srb(UE, 1);
   rrc_gNB_generate_RRCSetup(0, msg->crnti, ue_context_p, msg->du2cu_rrc_container, msg->du2cu_rrc_container_length);
 }
 
@@ -1330,7 +1349,7 @@ fallback_rrc_setup:
   random_value = random_value & 0x7fffffffff; /* random value is 39 bits */
 
   rrc_gNB_ue_context_t *new = rrc_gNB_create_ue_context(assoc_id, msg->crnti, rrc, random_value, msg->gNB_DU_ue_id);
-  new->ue_context.Srb[1].Active = 1;
+  activate_srb(&new->ue_context, 1);
   rrc_gNB_generate_RRCSetup(0, msg->crnti, new, msg->du2cu_rrc_container, msg->du2cu_rrc_container_length);
   return;
 }
@@ -2114,7 +2133,7 @@ void rrc_gNB_process_e1_bearer_context_setup_resp(e1ap_bearer_setup_resp_t *resp
   int nb_srb = 0;
   f1ap_srb_to_be_setup_t srbs[1];
   if (UE->Srb[2].Active == 0) {
-    UE->Srb[2].Active = 1;
+    activate_srb(UE, 2);
     nb_srb = 1;
     srbs[0].srb_id = 2;
     srbs[0].lcid = 2;