E1AP: Add PDU Session Resource To Remove List to Bearer Context Modification enc/dec

According to TS 38.463 - clause 9.2.2.4 and 9.3.3.12.
Also, fix response message by encoding choice IE only
with presence of modified PDU sessions.
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>

openair2/COMMON/e1ap_messages_types.h

@@ -475,6 +475,14 @@ typedef struct pdu_session_to_mod_s {
   DRB_nGRAN_to_mod_t DRBnGRanModList[E1AP_MAX_NUM_DRBS];
 } pdu_session_to_mod_t;
 
+/** PDU Session Resource To Remove List (3GPP TS 38.463 clause 9.3.3.12) */
+typedef struct {
+  // PDU Session ID (M)
+  long sessionId;
+  // Cause (O)
+  e1ap_cause_t cause;
+} pdu_session_to_remove_t;
+
 /**
  * Bearer Context Setup Request message, clause 9.2.2.1 of 3GPP TS 38.463
  */
@@ -534,6 +542,9 @@ typedef struct e1ap_bearer_mod_req_s {
   // NG-RAN PDU Session Resource To Modify List (O)
   int numPDUSessionsMod;
   pdu_session_to_mod_t pduSessionMod[E1AP_MAX_NUM_PDU_SESSIONS];
+  // NG-RAN PDU Session Resource To Remove List (O)
+  int numPDUSessionsRem;
+  pdu_session_to_remove_t pduSessionRem[E1AP_MAX_NUM_PDU_SESSIONS];
 } e1ap_bearer_mod_req_t;
 
 typedef struct e1ap_bearer_release_cmd_s {

openair2/E1AP/lib/e1ap_bearer_context_management.c

@@ -1631,6 +1631,20 @@ E1AP_E1AP_PDU_t *encode_E1_bearer_context_mod_request(const e1ap_bearer_mod_req_
       *ieC3_1 = e1_encode_pdu_session_to_mod_item(i);
     }
   }
+
+  // NG-RAN PDU Session Resource To Remove List (O)
+  if (in->numPDUSessionsRem) {
+    asn1cSequenceAdd(out->protocolIEs.list, E1AP_BearerContextModificationRequestIEs_t, remList);
+    E1AP_NG_RAN_BearerContextModificationRequest_t *msgNGRAN = encode_ng_ran_to_mod(remList);
+    msgNGRAN->id = E1AP_ProtocolIE_ID_id_PDU_Session_Resource_To_Remove_List;
+    msgNGRAN->criticality = E1AP_Criticality_reject;
+    msgNGRAN->value.present = E1AP_NG_RAN_BearerContextModificationRequest__value_PR_PDU_Session_Resource_To_Remove_List;
+    E1AP_PDU_Session_Resource_To_Remove_List_t *pdu2Remove = &msgNGRAN->value.choice.PDU_Session_Resource_To_Remove_List;
+    for (const pdu_session_to_remove_t *i = in->pduSessionRem; i < in->pduSessionRem + in->numPDUSessionsRem; i++) {
+      asn1cSequenceAdd(pdu2Remove->list, E1AP_PDU_Session_Resource_To_Remove_Item_t, ieC4_1);
+      ieC4_1->pDU_Session_ID = i->sessionId;
+    }
+  }
   return pdu;
 }
 
@@ -1854,6 +1868,19 @@ bool decode_E1_bearer_context_mod_request(const E1AP_E1AP_PDU_t *pdu, e1ap_beare
                     CHECK_E1AP_DEC(e1_decode_pdu_session_to_mod_item(out->pduSessionMod + i, modList->list.array[i]));
                   }
                   break;
+                case E1AP_ProtocolIE_ID_id_PDU_Session_Resource_To_Remove_List:
+                  /* PDU Session Resource To Remove List (see 9.3.3.12 of TS 38.463) */
+                  _E1_EQ_CHECK_INT(msgNGRAN->value.present,
+                                   E1AP_NG_RAN_BearerContextModificationRequest__value_PR_PDU_Session_Resource_To_Remove_List);
+                  E1AP_PDU_Session_Resource_To_Remove_List_t *remList = &msgNGRAN->value.choice.PDU_Session_Resource_To_Remove_List;
+                  out->numPDUSessionsRem = remList->list.count;
+                  // Loop through all PDU sessions to remove
+                  for (int i = 0; i < remList->list.count; i++) {
+                    E1AP_PDU_Session_Resource_To_Remove_Item_t *remItem = remList->list.array[i];
+                    pdu_session_to_remove_t *pduRem = &out->pduSessionRem[i];
+                    pduRem->sessionId = remItem->pDU_Session_ID;
+                  }
+                  break;
                 default:
                   PRINT_ERROR("Unknown msgNGRAN->id in E1 Setup Modification Request\n");
                   return false;
@@ -1924,6 +1951,9 @@ e1ap_bearer_mod_req_t cp_bearer_context_mod_request(const e1ap_bearer_mod_req_t
     cp.pduSession[i] = cp_pdu_session_item(&msg->pduSession[i]);
   for (int i = 0; i < msg->numPDUSessionsMod; i++)
     cp.pduSessionMod[i] = cp_pdu_session_to_mod_item(&msg->pduSessionMod[i]);
+  // Copy PDU sessions to remove (simple struct copy, no deep copy needed)
+  for (int i = 0; i < msg->numPDUSessionsRem; i++)
+    cp.pduSessionRem[i] = msg->pduSessionRem[i];
   return cp;
 }
 
@@ -2037,6 +2067,15 @@ bool eq_bearer_context_mod_request(const e1ap_bearer_mod_req_t *a, const e1ap_be
     if (!eq_pdu_session_to_mod_item(&a->pduSessionMod[i], &b->pduSessionMod[i]))
       return false;
   }
+  // PDU Sessions to Remove
+  _E1_EQ_CHECK_INT(a->numPDUSessionsRem, b->numPDUSessionsRem);
+  for (int i = 0; i < a->numPDUSessionsRem; i++) {
+    const pdu_session_to_remove_t *pduRemA = &a->pduSessionRem[i];
+    const pdu_session_to_remove_t *pduRemB = &b->pduSessionRem[i];
+    _E1_EQ_CHECK_LONG(pduRemA->sessionId, pduRemB->sessionId);
+    _E1_EQ_CHECK_INT(pduRemA->cause.type, pduRemB->cause.type);
+    _E1_EQ_CHECK_INT(pduRemA->cause.value, pduRemB->cause.value);
+  }
   return true;
 }
 
@@ -2114,6 +2153,7 @@ struct E1AP_E1AP_PDU *encode_E1_bearer_context_mod_response(const e1ap_bearer_mo
   ie2->criticality = E1AP_Criticality_reject;
   ie2->value.present = E1AP_BearerContextModificationResponseIEs__value_PR_GNB_CU_UP_UE_E1AP_ID;
   ie2->value.choice.GNB_CU_UP_UE_E1AP_ID = msg->gNB_cu_up_ue_id;
+  if (msg->numPDUSessionsMod > 0) {
     // NG-RAN PDU Session Resource Modified List (O)
     asn1cSequenceAdd(out->protocolIEs.list, E1AP_BearerContextModificationResponseIEs_t, ie3);
     ie3->id = E1AP_ProtocolIE_ID_id_System_BearerContextModificationResponse;
@@ -2173,13 +2213,11 @@ struct E1AP_E1AP_PDU *encode_E1_bearer_context_mod_response(const e1ap_bearer_mo
             asn1cSequenceAdd(drb_mod->flow_Failed_List->list, E1AP_QoS_Flow_Failed_Item_t, fail);
             encode_qos_flow_failed_item(fail, &drb->qosFlowsFailed[q]);
           }
-
           // PDCP Status Information (O)
           if (drb->pdcp_status) {
             asn1cCalloc(drb_mod->pDCP_SN_Status_Information, pdcp);
             *pdcp = encode_pdcp_status_info(drb->pdcp_status);
           }
-
           // UL UP Parameters (O)
           if (drb->numUpParam)
             drb_mod->uL_UP_Transport_Parameters = calloc_or_fail(1, sizeof(*drb_mod->uL_UP_Transport_Parameters));
@@ -2240,6 +2278,7 @@ struct E1AP_E1AP_PDU *encode_E1_bearer_context_mod_response(const e1ap_bearer_mo
         }
       }
     }
+  }
   return pdu;
 }
 

openair2/E1AP/lib/e1ap_lib_includes.h

@@ -78,6 +78,7 @@
 #include "E1AP_DRB-To-Modify-Item-NG-RAN.h"
 #include "E1AP_PDU-Session-Resource-To-Setup-Mod-Item.h"
 #include "E1AP_DRB-To-Setup-Mod-Item-NG-RAN.h"
+#include "E1AP_PDU-Session-Resource-To-Remove-Item.h"
 // E1 Bearer Context Modification Response
 #include "E1AP_PDU-Session-Resource-Modified-Item.h"
 #include "E1AP_DRB-Modified-List-NG-RAN.h"

openair2/E1AP/tests/e1ap_lib_test.c

@@ -538,6 +538,14 @@ static void test_bearer_context_modification_request(void)
       .DRBnGRanList[0] = drb_to_setup,
   };
 
+  // PDU Session to Remove
+  pdu_session_to_remove_t pdu_session_to_remove = {
+      .sessionId = 2,
+      // Note: cause is optional extension IE, currently encoding/decoding only handles sessionId
+      .cause.type = 0,
+      .cause.value = 0,
+  };
+
   // Initialize the Bearer Context Modification Request
   e1ap_bearer_mod_req_t orig = {
       .gNB_cu_cp_ue_id = 0x1234,
@@ -548,6 +556,8 @@ static void test_bearer_context_modification_request(void)
       .pduSession[0] = pdusession_setup_item,
       .numPDUSessionsMod = 1,
       .pduSessionMod[0] = pdusession_mod_item,
+      .numPDUSessionsRem = 1,
+      .pduSessionRem[0] = pdu_session_to_remove,
   };
   *orig.bearerContextStatus = BEARER_SUSPEND;
   *orig.inactivityTimer = 1000;