From e7eb1b1c3bda680b1ee94c2afa9b844b6d81e138 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@openairinterface.org>
Date: Wed, 5 Jun 2024 17:52:07 +0200
Subject: [PATCH] Store DRB UL TEID information at RRC

To be used later in the case of handover.
---
 openair2/RRC/NR/nr_rrc_defs.h |  2 ++
 openair2/RRC/NR/rrc_gNB.c     | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/openair2/RRC/NR/nr_rrc_defs.h b/openair2/RRC/NR/nr_rrc_defs.h
index 234c42daaf..de4bd5f5ec 100644
--- a/openair2/RRC/NR/nr_rrc_defs.h
+++ b/openair2/RRC/NR/nr_rrc_defs.h
@@ -205,6 +205,8 @@ typedef struct drb_s {
   } pdcp_config;
   // F1-U Downlink Tunnel Config (on DU side)
   f1u_tunnel_t du_tunnel_config;
+  // F1-U Uplink Tunnel Config (on CU-UP side)
+  f1u_tunnel_t cuup_tunnel_config;
 } drb_t;
 
 typedef enum {
diff --git a/openair2/RRC/NR/rrc_gNB.c b/openair2/RRC/NR/rrc_gNB.c
index 3d28a9fdaa..4e5593e8b5 100644
--- a/openair2/RRC/NR/rrc_gNB.c
+++ b/openair2/RRC/NR/rrc_gNB.c
@@ -1889,6 +1889,16 @@ static void store_du_f1u_tunnel(const f1ap_drb_to_be_setup_t *drbs, int n, gNB_R
   }
 }
 
+/*
+ * @brief Store F1-U UL TEID and address in RRC
+ */
+static void f1u_ul_gtp_update(f1u_tunnel_t *f1u, const up_params_t *p)
+{
+  f1u->teid = p->teId;
+  memcpy(&f1u->addr.buffer, &p->tlAddress, sizeof(uint8_t) * 4);
+  f1u->addr.length = sizeof(in_addr_t);
+}
+
 /* \brief use list of DRBs and send the corresponding bearer update message via
  * E1 to the CU of this UE. Also updates TEID info internally */
 static void e1_send_bearer_updates(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, int n, f1ap_drb_to_be_setup_t *drbs)
@@ -2165,6 +2175,15 @@ void rrc_gNB_process_e1_bearer_context_setup_resp(e1ap_bearer_setup_resp_t *resp
     rrc_pdu->param.gNB_teid_N3 = e1_pdu->teId;
     memcpy(&rrc_pdu->param.gNB_addr_N3.buffer, &e1_pdu->tlAddress, sizeof(uint8_t) * 4);
     rrc_pdu->param.gNB_addr_N3.length = sizeof(in_addr_t);
+
+    // save the tunnel address for the DRBs
+    for (int i = 0; i < e1_pdu->numDRBSetup; i++) {
+      DRB_nGRAN_setup_t *drb_config = &e1_pdu->DRBnGRanList[i];
+      // numUpParam only relevant in F1, but not monolithic
+      AssertFatal(drb_config->numUpParam <= 1, "can only up to one UP param\n");
+      drb_t *drb = get_drb(UE, drb_config->id);
+      f1u_ul_gtp_update(&drb->cuup_tunnel_config, &drb_config->UpParamList[0]);
+    }
   }
 
   /* Instruction towards the DU for DRB configuration and tunnel creation */