From c83ff4c388c5856c442ca7c5156fc8ddb505b054 Mon Sep 17 00:00:00 2001
From: Guido Casati <hello@guidocasati.com>
Date: Thu, 22 Feb 2024 12:19:30 +0100
Subject: [PATCH] Store F1-U downlink TL and TEID

- info coming from UE context setup/modification response messages in RRC
---
 openair2/COMMON/ngap_messages_types.h |  6 ++++--
 openair2/RRC/NR/nr_rrc_defs.h         | 12 ++++++++++++
 openair2/RRC/NR/rrc_gNB.c             | 12 ++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/openair2/COMMON/ngap_messages_types.h b/openair2/COMMON/ngap_messages_types.h
index caf0bff683..0c9be504ca 100644
--- a/openair2/COMMON/ngap_messages_types.h
+++ b/openair2/COMMON/ngap_messages_types.h
@@ -276,12 +276,14 @@ typedef struct pdusession_s {
   /* The transport layer address for the IP packets */
   pdu_session_type_t pdu_session_type;
   transport_layer_addr_t upf_addr;
-  /* S-GW Tunnel endpoint identifier */
+  /* Outgoing (UL) NG-U Tunnel Endpoint Identifier (S-GW/UPF) */
   uint32_t gtp_teid;
   /* Stores the DRB ID of the DRBs used by this PDU Session */
   uint8_t used_drbs[MAX_DRBS_PER_UE];
+  /* Incoming (DL) NG-U Tunnel Endpoint Identifier (S-GW/UPF) */
   uint32_t gNB_teid_N3;
   transport_layer_addr_t gNB_addr_N3;
+  /* Incoming (DL) NG-U Tunnel Endpoint Identifier (S-GW/UPF) */
   uint32_t UPF_teid_N3;
   transport_layer_addr_t UPF_addr_N3;
   nssai_t nssai;
@@ -306,7 +308,7 @@ typedef struct pdusession_setup_s {
   uint8_t pdu_session_type;
   transport_layer_addr_t gNB_addr;
 
-  /* UPF Tunnel endpoint identifier */
+  /* Incoming NG-U Tunnel Endpoint Identifier (S-GW/UPF) */
   uint32_t gtp_teid;
 
   /* qos flow list number */
diff --git a/openair2/RRC/NR/nr_rrc_defs.h b/openair2/RRC/NR/nr_rrc_defs.h
index f0d4039033..4dc17fd493 100644
--- a/openair2/RRC/NR/nr_rrc_defs.h
+++ b/openair2/RRC/NR/nr_rrc_defs.h
@@ -189,6 +189,16 @@ typedef struct pdu_session_param_s {
   uint8_t cause_value;
 } rrc_pdu_session_param_t;
 
+/**
+ * @brief F1-U tunnel configuration
+*/
+typedef struct f1u_tunnel_s {
+  /* Downlink F1-U Tunnel Endpoint Identifier (CU-UP/DU) */
+  uint32_t cuup_teid_f1u;
+  /* DL F1-U Transport Layer */
+  transport_layer_addr_t cuup_addr_f1u;
+} f1u_tunnel_t;
+
 typedef struct drb_s {
   int status;
   int defaultDRBid;
@@ -221,6 +231,8 @@ typedef struct drb_s {
       int cipheringDisabled;
     } ext1;
   } pdcp_config;
+  // F1-U
+  f1u_tunnel_t f1u_tunnel_config;
 } drb_t;
 
 typedef enum {
diff --git a/openair2/RRC/NR/rrc_gNB.c b/openair2/RRC/NR/rrc_gNB.c
index acc5233151..4e7505bcd0 100644
--- a/openair2/RRC/NR/rrc_gNB.c
+++ b/openair2/RRC/NR/rrc_gNB.c
@@ -1761,6 +1761,16 @@ static void fill_e1_bearer_modif(DRB_nGRAN_to_setup_t *drb_e1, const f1ap_drb_to
   drb_e1->DlUpParamList[0].teId = drb_f1->up_dl_tnl[0].teid;
 }
 
+/**
+ * @brief Store F1-U DL TL and TEID in RRC
+*/
+static void f1u_gtp_update(f1u_tunnel_t *f1u, const f1ap_drb_to_be_setup_t *drb_f1)
+{
+  f1u->cuup_teid_f1u = drb_f1->up_dl_tnl[0].teid;
+  memcpy(&f1u->cuup_addr_f1u.buffer, &drb_f1->up_dl_tnl[0].tl_address, sizeof(uint8_t) * 4);
+  f1u->cuup_addr_f1u.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 */
 static void e1_send_bearer_updates(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, int n, f1ap_drb_to_be_setup_t *drbs)
@@ -1782,6 +1792,8 @@ static void e1_send_bearer_updates(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, int n, f
     DevAssert(pdu_e1 != NULL);
     pdu_e1->sessionId = pdu_ue->param.pdusession_id;
     DRB_nGRAN_to_setup_t *drb_e1 = &pdu_e1->DRBnGRanModList[pdu_e1->numDRB2Modify];
+    f1u_gtp_update(&UE->established_drbs[drb_f1->drb_id].f1u_tunnel_config, drb_f1);
+    /* Fill E1 bearer context modification */
     fill_e1_bearer_modif(drb_e1, drb_f1);
     pdu_e1->numDRB2Modify += 1;
   }