Merge remote-tracking branch 'GuidoCasati/sdap-header-fix' into integration_2026_w28

SDAP header handling fixes (#249)

OAI SDAP treated SDAP header presence as a single PDU-session flag
(enable_sdap), so a valid asymmetric RRC config (UL header present, DL
header absent) caused the UE to parse downlink payload as an SDAP QFI
and drop traffic (e.g. IPv4 0x45 -> bogus QFI 5).

SDAP now follows RRC SDAP-Config per DRB and per direction from (TS
38.331 / TS 37.324). Header presence, QFI-to-DRB mapping, and
default-DRB fallback all derive from what RRC configured for each DRB.

In the new implementation, RRC (SDAP-Config IE) fills sdap_config_t per
DRB (role, defaultDRB, mapped QFIs), SDAP entity stores it in
qfi2drb_table + default_drb row to be used in the TX/RX data path.

Also, simplify mapping logic, improves E1 QoS-flow remap, and completes
UE reflective QoS mapping with the correct entity_role on new QFI rows.
Reviewed-by: Robert Schmidt <robert.schmidt@openairinterface.org>
Reviewed-by: Bartosz Podrygajlo <bartosz.podrygajlo@openairinterface.org>

doc/RRC/rrc-usage.md

@@ -90,9 +90,9 @@ the [MAC configuration](../MAC/mac-usage.md) as well for SIB configuration.
       `0xffffff` is a reserved value and means "no SD"
     Note that: SST=1, no SD is "eMBB"; SST=2, no SD is "URLLC"; SST=3, no SD
     is "mMTC"
-- `enable_sdap` (default: true): enable the use of the SDAP layer. If
-  deactivated, a transparent SDAP header is prepended to packets, but no
-  further processing is being done.
+- `enable_sdap` (default: true): set `sdap-HeaderUL` and `sdap-HeaderDL` to
+  present in the RRC `SDAP-Config` IE for SA PDU sessions. If false, both
+  headers are absent (per DRB). SDAP entities are still created, SDAP layer always enabled.
 - `cu_sibs` (default: `[]`) list of SIBs to give to the DU for transmission.
   Currently supported:
   - SIB2: serving-cell reselection parameters (configured in `sib2_config`)

openair2/GNB_APP/gnb_config.c

@@ -2443,7 +2443,7 @@ gNB_RRC_INST *RCconfig_NRRRC()
 
         nrrrc_config.num_plmn = set_plmn_config(nrrrc_config.plmn, k);
         nrrrc_config.enable_sdap = *GNBParamList.paramarray[i][GNB_ENABLE_SDAP_IDX].iptr;
-        LOG_I(GNB_APP, "SDAP layer is %s\n", nrrrc_config.enable_sdap ? "enabled" : "disabled");
+        LOG_I(GNB_APP, "SDAP UL/DL headers in RRC are %s\n", nrrrc_config.enable_sdap ? "present" : "absent");
         nrrrc_config.um_on_default_drb = *(GNBParamList.paramarray[i][GNB_UMONDEFAULTDRB_IDX].uptr);
 
       }//

openair2/GNB_APP/gnb_paramdef.h

@@ -102,7 +102,7 @@ typedef enum {
 #define GNB_CONFIG_STRING_1ST_ACTIVE_BWP                "first_active_bwp"
 #define GNB_CONFIG_STRING_LIMIT_RSRP_REPORT             "max_num_RSRP_reported"
 
-#define GNB_CONFIG_HLP_STRING_ENABLE_SDAP               "enable the SDAP layer\n"
+#define GNB_CONFIG_HLP_STRING_ENABLE_SDAP               "set sdap-HeaderUL/DL present in RRC SDAP-Config (false = both absent)\n"
 #define GNB_CONFIG_HLP_FORCE256QAMOFF                   "suppress activation of 256 QAM despite UE support"
 #define GNB_CONFIG_HLP_MAXMIMOLAYERS                    "limit on maxMIMO-layers for DL"
 #define GNB_CONFIG_HLP_DISABLE_HARQ                     "disable feedback for all HARQ processes (REL17 feature)"

openair2/LAYER2/nr_pdcp/cucp_cuup_handler.c

@@ -427,9 +427,15 @@ void e1_bearer_context_modif(const e1ap_bearer_mod_req_t *req)
         DevAssert(to_modif->numQosFlowsMod <= E1AP_MAX_NUM_QOS_FLOWS);
         modified->numQosFlowSetup = to_modif->numQosFlowsMod;
 
-        uint8_t qfi_list[E1AP_MAX_NUM_QOS_FLOWS];
+        sdap_config_t sdap = {
+            .pdusession_id = req_pdu_mod->sessionId,
+            .drb_id = to_modif->id,
+            .mappedQFIs2AddCount = to_modif->numQosFlowsMod,
+        };
+
         for (int q = 0; q < to_modif->numQosFlowsMod; q++) {
-          modified->qosFlows[q].qfi = qfi_list[q] = to_modif->qosFlows[q].qfi;
+          sdap.mappedQFIs2Add[q] = to_modif->qosFlows[q].qfi;
+          modified->qosFlows[q].qfi = to_modif->qosFlows[q].qfi;
         }
 
         LOG_D(NR_RRC,
@@ -438,11 +444,7 @@ void e1_bearer_context_modif(const e1ap_bearer_mod_req_t *req)
               req_pdu_mod->sessionId,
               to_modif->id,
               to_modif->numQosFlowsMod);
-        nr_sdap_entity_update_qos_flows(req->gNB_cu_up_ue_id,
-                                        req_pdu_mod->sessionId,
-                                        to_modif->id,
-                                        qfi_list,
-                                        to_modif->numQosFlowsMod);
+        nr_sdap_entity_update_qos_flows(req->gNB_cu_up_ue_id, &sdap);
       }
 
       if (to_modif->pdcp_config && to_modif->pdcp_config->pDCP_Reestablishment) {

openair2/RRC/NR/rrc_gNB_NGAP.c

@@ -345,8 +345,8 @@ static DRB_nGRAN_to_setup_t fill_e1_drb_to_setup(const drb_t *rrc_drb,
   drb_ngran.id = rrc_drb->drb_id;
 
   drb_ngran.sdap_config.defaultDRB = (session->sdap_config.default_drb == drb_ngran.id);
-  drb_ngran.sdap_config.sDAP_Header_UL = session->sdap_config.header_ul_absent ? false : true;
-  drb_ngran.sdap_config.sDAP_Header_DL = session->sdap_config.header_dl_absent ? false : true;
+  drb_ngran.sdap_config.sDAP_Header_UL = !session->sdap_config.header_ul_absent;
+  drb_ngran.sdap_config.sDAP_Header_DL = !session->sdap_config.header_dl_absent;
 
   drb_ngran.pdcp_config = set_bearer_context_pdcp_config(rrc_drb->pdcp_config, um_on_default_drb, redcap_cap);
 

openair2/SDAP/nr_sdap/nr_sdap.c

@@ -162,7 +162,7 @@ bool sdap_data_req(protocol_ctxt_t *ctxt_p,
                                 rqi);
 }
 
-void sdap_data_ind(int pdcp_entity, int is_gnb, int pdusession_id, ue_id_t ue_id, char *buf, int size)
+void sdap_data_ind(int drb_id, int is_gnb, int pdusession_id, ue_id_t ue_id, char *buf, int size)
 {
   nr_sdap_entity_t *sdap_entity;
   sdap_entity = nr_sdap_get_entity(ue_id, pdusession_id);
@@ -172,13 +172,7 @@ void sdap_data_ind(int pdcp_entity, int is_gnb, int pdusession_id, ue_id_t ue_id
     return;
   }
 
-  sdap_entity->rx_entity(sdap_entity,
-                         pdcp_entity,
-                         is_gnb,
-                         pdusession_id,
-                         ue_id,
-                         buf,
-                         size);
+  sdap_entity->rx_entity(sdap_entity, drb_id, is_gnb, pdusession_id, ue_id, buf, size);
 }
 
 static void *sdap_tun_read_thread(void *arg)
@@ -213,14 +207,6 @@ static void *sdap_tun_read_thread(void *arg)
 
     LOG_D(SDAP, "read data of size %d\n", len);
 
-    if (!entity->is_gnb && entity->enable_sdap && (entity->qfi < 0 || entity->qfi >= SDAP_MAX_QFI)) {
-      LOG_W(SDAP,
-            "Dropping UL SDU for UE %ld PDU session %d: no QoS rule QFI available for SDAP header\n",
-            entity->ue_id,
-            entity->pdusession_id);
-      continue;
-    }
-
     protocol_ctxt_t ctxt = {.enb_flag = entity->is_gnb, .rntiMaybeUEid = entity->ue_id};
 
     bool dc = entity->is_gnb ? false : SDAP_HDR_UL_DATA_PDU;

openair2/SDAP/nr_sdap/nr_sdap.h

@@ -37,7 +37,7 @@ bool sdap_data_req(protocol_ctxt_t *ctxt_p,
  * Uplink   - gNB
  * Downlink - nrUE
  */
-void sdap_data_ind(int pdcp_entity, int is_gnb, int pdusession_id, ue_id_t ue_id, char *buf, int size);
+void sdap_data_ind(int drb_id, int is_gnb, int pdusession_id, ue_id_t ue_id, char *buf, int size);
 
 void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id, int pdu_session_id);
 void create_ue_ip_if(const char *ipv4, const char *ipv6, int ue_id, int pdu_session_id, bool is_default);

openair2/SDAP/nr_sdap/nr_sdap_entity.h

@@ -20,7 +20,6 @@
 #define SDAP_HDR_UL_CTRL_PDU        (0)
 #define SDAP_HDR_LENGTH             (1)
 #define SDAP_MAX_QFI                (64)
-#define SDAP_MAP_RULE_EMPTY         (0)
 #define SDAP_NO_MAPPING_RULE        (0)
 #define SDAP_REFLECTIVE_MAPPING     (1)
 #define SDAP_RQI_HANDLING           (1)
@@ -78,17 +77,16 @@ typedef struct sdap_configuration_s {
 
 typedef struct nr_sdap_entity_s {
   ue_id_t ue_id;
-  int default_drb;
   /// sdap_tun_read_thread needs to know if we are gNB/UE, so for noS1 mode,
   /// store which one we are
   bool is_gnb;
-  bool enable_sdap;
   int pdusession_id;
   int pdusession_sock;
   pthread_t pdusession_thread;
   bool stop_thread;
   int qfi;
 
+  qfi2drb_t default_drb;
   qfi2drb_t qfi2drb_table[SDAP_MAX_QFI];
 
   void (*qfi2drb_map_update)(struct nr_sdap_entity_s *entity, const sdap_config_t *sdap);
@@ -97,7 +95,7 @@ typedef struct nr_sdap_entity_s {
                           const uint8_t qfi,
                           const uint8_t drb_id,
                           const uint8_t role);
-  int (*qfi2drb_map)(struct nr_sdap_entity_s *entity, uint8_t qfi);
+  const qfi2drb_t *(*qfi2drb_map)(const struct nr_sdap_entity_s *entity, uint8_t qfi);
 
   nr_sdap_ul_hdr_t (*sdap_construct_ctrl_pdu)(uint8_t qfi);
   int (*sdap_map_ctrl_pdu)(struct nr_sdap_entity_s *entity, int map_type, uint8_t dl_qfi);
@@ -116,13 +114,7 @@ typedef struct nr_sdap_entity_s {
                     const uint8_t qfi,
                     const bool rqi);
 
-  void (*rx_entity)(struct nr_sdap_entity_s *entity,
-                    int pdcp_entity,
-                    int is_gnb,
-                    int pdusession_id,
-                    ue_id_t ue_id,
-                    char *buf,
-                    int size);
+  void (*rx_entity)(struct nr_sdap_entity_s *entity, int drb_id, int is_gnb, int pdusession_id, ue_id_t ue_id, char *buf, int size);
 
   /* List of entities */
   struct nr_sdap_entity_s *next_entity;
@@ -182,7 +174,7 @@ bool nr_sdap_delete_ue_entities(ue_id_t ue_id);
  */
 void nr_reconfigure_sdap_entity(NR_SDAP_Config_t *sdap_config, ue_id_t ue_id, int pdusession_id, int drb_id);
 
-void nr_sdap_entity_update_qos_flows(ue_id_t ue_id, int pdusession_id, int drb_id, const uint8_t *qfis, int n_qfis);
+void nr_sdap_entity_update_qos_flows(ue_id_t ue_id, sdap_config_t *sdap);
 
 void set_qfi(uint8_t qfi, uint8_t pduid, ue_id_t ue_id);
 #endif