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openairinterface5g/openair3/NGAP/ngap_gNB_decoder.c
T
Guido Casati bc9c59f186 Add NGAP RAN Status Transfer enc/dec and handlers (UL and DL) 
According to 4.9.1.3.3 of 3GPP TS 23.502:

> 2a. - 2c. The S-RAN sends the Uplink RAN Status Transfer message to the S-AMF,
> as specified in TS 36.300 [46] and TS 38.300 [9]. The S-RAN may omit sending
> this message if none of the radio bearers of the UE shall be treated with PDCP status preservation.

TS 38.300 says:
> For DRBs not configured with DAPS, the source gNB sends the SN STATUS TRANSFER message to the target
> gNB to convey the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of DRBs for
> which PDCP status preservation applies (i.e. for RLC AM). The uplink PDCP SN receiver status includes at
> least the PDCP SN of the first missing UL PDCP SDU and may include a bit map of the receive status of the out
> of sequence UL PDCP SDUs that the UE needs to retransmit in the target cell, if any. The downlink PDCP SN
> transmitter status indicates the next PDCP SN that the target gNB shall assign to new PDCP SDUs, not having a
> PDCP SN yet.

i.e., for DRBs for which PDCP status preservation applies (i.e. for RLC AM), which is is our case.

This commit introduces full support for NG-RAN Status Transfer message handling
(TS 38.413 §9.2.3.13-14) in CU. It enables correct state transfer of PDCP COUNT
values (SN + HFN) during mobility or recovery scenarios.

Summary of changes - NGAP:
* Added encoding/decoding support for UL/DL RAN Status Transfer message
* Defined structures for: ngap_drb_count_value_t, ngap_drb_status_t,
  ngap_ran_status_container_t, ngap_ran_status_transfer_t
2025-09-18 11:34:31 +02:00

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/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.1 (the "License"); you may not use this file
* except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.openairinterface.org/?page_id=698
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
/*! \file ngap_gNB_decoder.c
* \brief ngap pdu decode procedures for gNB
* \author Yoshio INOUE, Masayuki HARADA
* \email yoshio.inoue@fujitsu.com,masayuki.harada@fujitsu.com (yoshio.inoue%40fujitsu.com%2cmasayuki.harada%40fujitsu.com)
* \date 2020
* \version 0.1
*/
#include "ngap_gNB_decoder.h"
#include <stdio.h>
#include <stdlib.h>
#include "ngap_msg_includes.h"
#include "T.h"
#include "aper_decoder.h"
#include "asn_application.h"
#include "asn_codecs.h"
#include "assertions.h"
#include "common/utils/T/T.h"
#include "ngap_common.h"
static int ngap_gNB_decode_initiating_message(NGAP_NGAP_PDU_t *pdu) {
asn_encode_to_new_buffer_result_t res = { NULL, {0, NULL, NULL} };
DevAssert(pdu != NULL);
switch(pdu->choice.initiatingMessage->procedureCode) {
case NGAP_ProcedureCode_id_DownlinkNASTransport:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_InitialContextSetup:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_UEContextRelease:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_Paging:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
NGAP_INFO("Paging initiating message\n");
free(res.buffer);
break;
case NGAP_ProcedureCode_id_PDUSessionResourceSetup:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("PDUSESSIONSetup initiating message\n");
break;
case NGAP_ProcedureCode_id_HandoverPreparation:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("Handover Preparation initiating message\n");
break;
case NGAP_ProcedureCode_id_PDUSessionResourceModify:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("PDUSESSIONModify initiating message\n");
break;
case NGAP_ProcedureCode_id_PDUSessionResourceRelease:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("PDUSESSIONRelease initiating message\n");
break;
case NGAP_ProcedureCode_id_ErrorIndication:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("TODO ErrorIndication initiating message\n");
break;
case NGAP_ProcedureCode_id_HandoverResourceAllocation:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("Handover Resource Allocation initiating message\n");
break;
case NGAP_ProcedureCode_id_DownlinkRANStatusTransfer:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
NGAP_INFO("DL RAN Status Transfer initiating message\n");
break;
default:
NGAP_ERROR("Unknown procedure ID (%d) for initiating message\n",
(int)pdu->choice.initiatingMessage->procedureCode);
AssertFatal( 0, "Unknown procedure ID (%d) for initiating message\n",
(int)pdu->choice.initiatingMessage->procedureCode);
return -1;
}
return 0;
}
static int ngap_gNB_decode_successful_outcome(NGAP_NGAP_PDU_t *pdu) {
asn_encode_to_new_buffer_result_t res = { NULL, {0, NULL, NULL} };
DevAssert(pdu != NULL);
switch(pdu->choice.successfulOutcome->procedureCode) {
case NGAP_ProcedureCode_id_NGSetup:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_PathSwitchRequest:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_PDUSessionResourceModifyIndication:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_HandoverPreparation:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
default:
NGAP_ERROR("Unknown procedure ID (%d) for successfull outcome message\n",
(int)pdu->choice.successfulOutcome->procedureCode);
return -1;
}
return 0;
}
static int ngap_gNB_decode_unsuccessful_outcome(NGAP_NGAP_PDU_t *pdu) {
asn_encode_to_new_buffer_result_t res = { NULL, {0, NULL, NULL} };
DevAssert(pdu != NULL);
switch(pdu->choice.unsuccessfulOutcome->procedureCode) {
case NGAP_ProcedureCode_id_NGSetup:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
case NGAP_ProcedureCode_id_PathSwitchRequest:
res = asn_encode_to_new_buffer(NULL, ATS_CANONICAL_XER, &asn_DEF_NGAP_NGAP_PDU, pdu);
free(res.buffer);
break;
default:
NGAP_ERROR("Unknown procedure ID (%d) for unsuccessfull outcome message\n",
(int)pdu->choice.unsuccessfulOutcome->procedureCode);
return -1;
}
return 0;
}
int ngap_gNB_decode_pdu(NGAP_NGAP_PDU_t *pdu, const uint8_t *const buffer,
const uint32_t length) {
asn_dec_rval_t dec_ret;
DevAssert(pdu != NULL);
DevAssert(buffer != NULL);
asn_codec_ctx_t st = {.max_stack_size = 100 * 1000}; // if we enable asn1c debug the stack size become large
dec_ret = aper_decode(&st, &asn_DEF_NGAP_NGAP_PDU, (void **)&pdu, buffer, length, 0, 0);
if (dec_ret.code != RC_OK) {
NGAP_ERROR("Failed to decode pdu\n");
return -1;
}
switch(pdu->present) {
case NGAP_NGAP_PDU_PR_initiatingMessage:
return ngap_gNB_decode_initiating_message(pdu);
case NGAP_NGAP_PDU_PR_successfulOutcome:
return ngap_gNB_decode_successful_outcome(pdu);
case NGAP_NGAP_PDU_PR_unsuccessfulOutcome:
return ngap_gNB_decode_unsuccessful_outcome(pdu);
default:
NGAP_DEBUG("Unknown presence (%d) or not implemented\n", (int)pdu->present);
break;
}
return -1;
}
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