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Refactor NGAP decodePDUSessionResourceSetup/Modify to improve RRC/NGAP separation

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Motivation of the commit:

Previously, the RRC module on the NGAP interface directly handled ASN.1 decoding
of NGAP PDU Session Resource items, that was directly stored in pdusession_t, i.e.
in the UE context. Decode logic between Setup and Modify was also duplicated.,
e.g. fill_qos/fill_qos2. The idea behind this change is to achieve this flow:
(1) NGAP handler: decoding (2) ITTI to RRC: transfer decoded message (3) RRC
handler: process decoded message, e.g. store in UE context, etc..

The goal of this commit is to:

* improve the NGAP decoding library by adding decoding functions
* let RRC handle the already decoded data
* enhance error handling, with decode failures now consistently detected and rejected early
* have a cleaner, more maintainable code with fewer duplications and a clearer separation of modules

Changes:
* Moved all ASN.1 decode logic for PDU Session Resource items into the NGAP library
* Introduced decode functions for NGAP IEs whenever necessary, e.g. decode_TNLInformation
decode_pdusession_transfer
* Removed duplicate fill_qos functions and centralized QoS handling in NGAP
* Added function to copy from NGAP PDU Session Resource item to RRC pdusession_t: this actually
  replaces decodePDUSessionResourceSetup in RRC, copying from the decoded NGAP struct to
  the UE context pdusession_t
This commit is contained in:
Guido Casati
2025-06-18 10:52:15 +02:00
parent 48a4c2b0ab
commit 0c408875a3
5 changed files with 177 additions and 223 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair3/NGAP/ngap_gNB_handlers.c
+139 -7
View File
@@ -694,6 +694,99 @@ static int ngap_gNB_handle_error_indication(sctp_assoc_t assoc_id, uint32_t stre
return 0;
}
static void *decode_pdusession_transfer(const asn_TYPE_descriptor_t *td, const OCTET_STRING_t buf)
{
void *decoded = NULL;
asn_codec_ctx_t ctx = {.max_stack_size = 100 * 1000};
asn_dec_rval_t rval = aper_decode(&ctx, td, &decoded, buf.buf, buf.size, 0, 0);
if (rval.code != RC_OK) {
NGAP_ERROR("Decoding failed for %s\n", td->name);
return NULL;
}
return decoded;
}
static pdusession_level_qos_parameter_t fill_qos(uint8_t qfi, const NGAP_QosFlowLevelQosParameters_t *params)
{
pdusession_level_qos_parameter_t out = {0};
// QFI
out.qfi = qfi;
AssertFatal(params != NULL, "QoS parameters are NULL\n");
// QosCharacteristics
const NGAP_QosCharacteristics_t *qosChar = &params->qosCharacteristics;
AssertFatal(qosChar != NULL, "QoS characteristics are NULL\n");
if (qosChar->present == NGAP_QosCharacteristics_PR_nonDynamic5QI) {
AssertFatal(qosChar->choice.nonDynamic5QI != NULL, "nonDynamic5QI is NULL\n");
out.fiveQI_type = NON_DYNAMIC;
out.fiveQI = qosChar->choice.nonDynamic5QI->fiveQI;
} else if (qosChar->present == NGAP_QosCharacteristics_PR_dynamic5QI) {
AssertFatal(qosChar->choice.dynamic5QI != NULL, "dynamic5QI is NULL\n");
out.fiveQI_type = DYNAMIC;
out.fiveQI = *qosChar->choice.dynamic5QI->fiveQI;
} else {
AssertFatal(0, "Unsupported QoS Characteristics present value: %d\n", qosChar->present);
}
// Allocation and Retention Priority
const NGAP_AllocationAndRetentionPriority_t *arp = &params->allocationAndRetentionPriority;
out.allocation_retention_priority.priority_level = arp->priorityLevelARP;
out.allocation_retention_priority.pre_emp_capability = arp->pre_emptionCapability;
out.allocation_retention_priority.pre_emp_vulnerability = arp->pre_emptionVulnerability;
return out;
}
static gtpu_tunnel_t decode_TNLInformation(const NGAP_GTPTunnel_t *gTPTunnel_p)
{
gtpu_tunnel_t out = {0};
// Transport layer address
memcpy(out.addr.buffer, gTPTunnel_p->transportLayerAddress.buf, gTPTunnel_p->transportLayerAddress.size);
out.addr.length = gTPTunnel_p->transportLayerAddress.size - gTPTunnel_p->transportLayerAddress.bits_unused;
// GTP tunnel endpoint ID
OCTET_STRING_TO_INT32(&gTPTunnel_p->gTP_TEID, out.teid);
return out;
}
/** @brief Decode PDU Session Resource Setup Request Transfer (9.3.4.1 3GPP TS 38.413) */
static bool decodePDUSessionResourceSetup(pdusession_transfer_t *out, const OCTET_STRING_t in)
{
void *decoded = decode_pdusession_transfer(&asn_DEF_NGAP_PDUSessionResourceSetupRequestTransfer, in);
if (!decoded) {
LOG_E(NR_RRC, "Failed to decode PDUSessionResourceSetupRequestTransfer\n");
return false;
}
NGAP_PDUSessionResourceSetupRequestTransfer_t *pdusessionTransfer = (NGAP_PDUSessionResourceSetupRequestTransfer_t *)decoded;
for (int i = 0; i < pdusessionTransfer->protocolIEs.list.count; i++) {
NGAP_PDUSessionResourceSetupRequestTransferIEs_t *pdusessionTransfer_ies = pdusessionTransfer->protocolIEs.list.array[i];
switch (pdusessionTransfer_ies->id) {
// UL NG-U UP TNL Information (Mandatory)
case NGAP_ProtocolIE_ID_id_UL_NGU_UP_TNLInformation:
out->n3_incoming = decode_TNLInformation(pdusessionTransfer_ies->value.choice.UPTransportLayerInformation.choice.gTPTunnel);
break;
// PDU Session Type (Mandatory)
case NGAP_ProtocolIE_ID_id_PDUSessionType:
out->pdu_session_type = pdusessionTransfer_ies->value.choice.PDUSessionType;
break;
// QoS Flow Setup Request List (Mandatory)
case NGAP_ProtocolIE_ID_id_QosFlowSetupRequestList:
out->nb_qos = pdusessionTransfer_ies->value.choice.QosFlowSetupRequestList.list.count;
for (int i = 0; i < out->nb_qos; i++) {
NGAP_QosFlowSetupRequestItem_t *item = pdusessionTransfer_ies->value.choice.QosFlowSetupRequestList.list.array[i];
out->qos[i] = fill_qos(item->qosFlowIdentifier, &item->qosFlowLevelQosParameters);
}
break;
default:
LOG_D(NR_RRC, "Unhandled optional IE %ld\n", pdusessionTransfer_ies->id);
}
}
ASN_STRUCT_FREE(asn_DEF_NGAP_PDUSessionResourceSetupRequestTransfer, pdusessionTransfer);
return true;
}
static int ngap_gNB_handle_initial_context_request(sctp_assoc_t assoc_id, uint32_t stream, NGAP_NGAP_PDU_t *pdu)
{
int i;
@@ -767,8 +860,11 @@ static int ngap_gNB_handle_initial_context_request(sctp_assoc_t assoc_id, uint32
if (item_p->nAS_PDU) {
msg->pdusession[i].nas_pdu = create_byte_array(item_p->nAS_PDU->size, item_p->nAS_PDU->buf);
}
OCTET_STRING_t *transfer = &item_p->pDUSessionResourceSetupRequestTransfer;
msg->pdusession[i].pdusessionTransfer = create_byte_array(transfer->size, transfer->buf);
bool ret = decodePDUSessionResourceSetup(&msg->pdusession[i].pdusessionTransfer, item_p->pDUSessionResourceSetupRequestTransfer);
if (!ret) {
NGAP_ERROR("Failed to decode pDUSessionResourceSetupRequestTransfer in NG Initial Context Setup Request\n");
return -1;
}
}
}
@@ -941,11 +1037,14 @@ static int ngap_gNB_handle_pdusession_setup_request(sctp_assoc_t assoc_id, uint3
// S-NSSAI
msg->pdusession[i].nssai = decode_ngap_nssai(&item_p->s_NSSAI);
OCTET_STRING_t *transfer = &item_p->pDUSessionResourceSetupRequestTransfer;
msg->pdusession[i].nas_pdu = create_byte_array(item_p->pDUSessionNAS_PDU->size, item_p->pDUSessionNAS_PDU->buf);
msg->pdusession[i].pdusessionTransfer = create_byte_array(transfer->size, transfer->buf);
bool ret = decodePDUSessionResourceSetup(&msg->pdusession[i].pdusessionTransfer, item_p->pDUSessionResourceSetupRequestTransfer);
if (!ret) {
NGAP_ERROR("Failed to decode pDUSessionResourceSetupRequestTransfer in NG Setup Request\n");
return -1;
}
}
itti_send_msg_to_task(TASK_RRC_GNB, ue_desc_p->gNB_instance->instance, message_p);
itti_send_msg_to_task(TASK_RRC_GNB, ue_desc_p->gNB_instance->instance, message_p);
return 0;
}
@@ -1039,6 +1138,37 @@ static int ngap_gNB_handle_paging(sctp_assoc_t assoc_id, uint32_t stream, NGAP_N
return 0;
}
static bool decodePDUSessionResourceModify(pdusession_transfer_t *out, const OCTET_STRING_t in)
{
void *decoded = decode_pdusession_transfer(&asn_DEF_NGAP_PDUSessionResourceModifyRequestTransfer, in);
if (!decoded) {
LOG_E(NR_RRC, "Failed to decode PDUSessionResourceModifyRequestTransfer\n");
return false;
}
NGAP_PDUSessionResourceModifyRequestTransfer_t *pdusessionTransfer = (NGAP_PDUSessionResourceModifyRequestTransfer_t *)decoded;
for (int j = 0; j < pdusessionTransfer->protocolIEs.list.count; j++) {
NGAP_PDUSessionResourceModifyRequestTransferIEs_t *pdusessionTransfer_ies = pdusessionTransfer->protocolIEs.list.array[j];
switch (pdusessionTransfer_ies->id) {
/* optional QosFlowAddOrModifyRequestList */
case NGAP_ProtocolIE_ID_id_QosFlowAddOrModifyRequestList:
out->nb_qos = pdusessionTransfer_ies->value.choice.QosFlowAddOrModifyRequestList.list.count;
for (int i = 0; i < out->nb_qos; i++) {
NGAP_QosFlowAddOrModifyRequestItem_t *item =
pdusessionTransfer_ies->value.choice.QosFlowAddOrModifyRequestList.list.array[i];
out->qos[i] = fill_qos(item->qosFlowIdentifier, item->qosFlowLevelQosParameters);
}
break;
default:
LOG_E(NR_RRC, "Unhandled optional IE %ld\n", pdusessionTransfer_ies->id);
return false;
}
}
ASN_STRUCT_FREE(asn_DEF_NGAP_PDUSessionResourceModifyRequestTransfer, pdusessionTransfer);
return true;
}
static int ngap_gNB_handle_pdusession_modify_request(sctp_assoc_t assoc_id, uint32_t stream, NGAP_NGAP_PDU_t *pdu)
{
ngap_gNB_amf_data_t *amf_desc_p = NULL;
@@ -1121,8 +1251,10 @@ static int ngap_gNB_handle_pdusession_modify_request(sctp_assoc_t assoc_id, uint
// check for the NAS PDU
if (item_p->nAS_PDU != NULL && item_p->nAS_PDU->size > 0) {
msg->pdusession[i].nas_pdu = create_byte_array(item_p->nAS_PDU->size, item_p->nAS_PDU->buf);
OCTET_STRING_t *transfer = &item_p->pDUSessionResourceModifyRequestTransfer;
msg->pdusession[i].pdusessionTransfer = create_byte_array(transfer->size, transfer->buf);
if (!decodePDUSessionResourceModify(&msg->pdusession[i].pdusessionTransfer, item_p->pDUSessionResourceModifyRequestTransfer)) {
NGAP_ERROR("Failed to decode pDUSessionResourceModifyRequestTransfer\n");
return -1;
}
} else {
LOG_W(NGAP, "received pdu session modify with void content for UE %u, pdu session %lu\n", msg->gNB_ue_ngap_id, item_p->pDUSessionID);
continue;