/*
 * Copyright (C) 2019,2020 by Sukchan Lee <acetcom@gmail.com>
 *
 * This file is part of Open5GS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "nas-security.h"

#include "ngap-path.h"
#include "nas-path.h"
#include "amf-path.h"
#include "sbi-path.h"

#include "gmm-handler.h"

#undef OGS_LOG_DOMAIN
#define OGS_LOG_DOMAIN __gmm_log_domain

int gmm_handle_registration_request(amf_ue_t *amf_ue,
        ogs_nas_5gs_registration_request_t *registration_request)
{
    int served_tai_index = 0;

    ran_ue_t *ran_ue = NULL;
    ogs_nas_5gs_registration_type_t *registration_type = NULL;
    ogs_nas_5gs_mobile_identity_t *mobile_identity = NULL;
    ogs_nas_5gs_mobile_identity_header_t *mobile_identity_header = NULL;
    ogs_nas_5gs_mobile_identity_guti_t *mobile_identity_guti = NULL;
    ogs_nas_ue_security_capability_t *ue_security_capability = NULL;
    ogs_nas_5gs_guti_t nas_guti;

    ogs_assert(amf_ue);
    ran_ue = amf_ue->ran_ue;
    ogs_assert(ran_ue);

    ogs_assert(registration_request);
    registration_type = &registration_request->registration_type;
    ogs_assert(registration_type);
    mobile_identity = &registration_request->mobile_identity;
    ogs_assert(mobile_identity);
    ue_security_capability = &registration_request->ue_security_capability;
    ogs_assert(ue_security_capability);

    if (!mobile_identity->length || !mobile_identity->buffer) {
        ogs_error("No Mobile Identity");
        nas_5gs_send_registration_reject(amf_ue,
            OGS_5GMM_CAUSE_SEMANTICALLY_INCORRECT_MESSAGE);
        return OGS_ERROR;
    }

    mobile_identity_header =
            (ogs_nas_5gs_mobile_identity_header_t *)mobile_identity->buffer;

    switch (mobile_identity_header->type) {
    case OGS_NAS_5GS_MOBILE_IDENTITY_SUCI:
        amf_ue_set_suci(amf_ue, mobile_identity);
        ogs_debug("[%s]    SUCI", amf_ue->suci);
        break;
    case OGS_NAS_5GS_MOBILE_IDENTITY_GUTI:
        mobile_identity_guti =
            (ogs_nas_5gs_mobile_identity_guti_t *)mobile_identity->buffer;
        if (!mobile_identity_guti) {
            ogs_error("No mobile identity");
            return OGS_ERROR;
        }

        ogs_nas_5gs_mobile_identity_guti_to_nas_guti(
            mobile_identity_guti, &nas_guti);

        ogs_debug("[%s]    5G-S_GUTI[AMF_ID:0x%x,M_TMSI:0x%x]",
            AMF_UE_HAVE_SUCI(amf_ue) ? amf_ue->suci : "Unknown ID",
            ogs_amf_id_hexdump(&nas_guti.amf_id), nas_guti.m_tmsi);
        break;
    default:
        ogs_error("Unknown SUCI type [%d]", mobile_identity_header->type);
        break;
    }


    /* Set 5GS Registration Type */
    memcpy(&amf_ue->nas.registration, registration_type,
            sizeof(ogs_nas_5gs_registration_type_t));
    amf_ue->nas.message_type = OGS_NAS_5GS_REGISTRATION_REQUEST;
    ogs_debug("[%s]    OGS_NAS_5GS TYPE[%d] TSC[%d] KSI[%d] REGISTRATION[0x%x]",
            amf_ue->suci, amf_ue->nas.message_type,
            amf_ue->nas.tsc, amf_ue->nas.ksi, amf_ue->nas.data);
    /*
     * REGISTRATION_REQUEST
     *   Clear EBI generator
     *   Clear Timer and Message
     *
     * TAU_REQUEST
     *   Clear Timer and Message
     *
     * SERVICE_REQUEST
     *   Clear Timer and Message
     *
     * EXTENDED_SERVICE_REQUEST
     *   Clear Timer and Message
     */
    CLEAR_AMF_UE_ALL_TIMERS(amf_ue);

    if (SECURITY_CONTEXT_IS_VALID(amf_ue)) {
        ogs_kdf_kgnb_and_kn3iwf(
                amf_ue->kamf, amf_ue->ul_count.i32,
                amf_ue->nas.access_type, amf_ue->kgnb);
        ogs_kdf_nh_gnb(amf_ue->kamf, amf_ue->kgnb, amf_ue->nh);
        amf_ue->nhcc = 1;
    }

    ogs_debug("[%s]    OLD TAI[PLMN_ID:%06x,TAC:%d]", amf_ue->suci,
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac.v);
    ogs_debug("[%s]    OLD NR_CGI[PLMN_ID:%06x,CELL_ID:0x%llx]", amf_ue->suci,
            ogs_plmn_id_hexdump(&amf_ue->cgi.plmn_id),
            (long long)amf_ue->cgi.cell_id);
    ogs_debug("[%s]    TAI[PLMN_ID:%06x,TAC:%d]", amf_ue->suci,
            ogs_plmn_id_hexdump(&ran_ue->saved.tai.plmn_id),
            ran_ue->saved.tai.tac.v);
    ogs_debug("[%s]    NR_CGI[PLMN_ID:%06x,CELL_ID:0x%llx]", amf_ue->suci,
            ogs_plmn_id_hexdump(&ran_ue->saved.cgi.plmn_id),
            (long long)ran_ue->saved.cgi.cell_id);

    /* Copy TAI and ECGI from ran_ue */
    memcpy(&amf_ue->tai, &ran_ue->saved.tai, sizeof(ogs_5gs_tai_t));
    memcpy(&amf_ue->cgi, &ran_ue->saved.cgi, sizeof(ogs_nr_cgi_t));

    /* Check TAI */
    served_tai_index = amf_find_served_tai(&amf_ue->tai);
    if (served_tai_index < 0) {
        /* Send Registration Reject */
        ogs_warn("[%s] Cannot find Served TAI[PLMN_ID:%06x,TAC:%d]",
            amf_ue->suci,
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac.v);
        nas_5gs_send_registration_reject(amf_ue,
            OGS_5GMM_CAUSE_TRACKING_AREA_NOT_ALLOWED);
        return OGS_ERROR;
    }
    ogs_debug("[%s]    SERVED_TAI_INDEX[%d]", amf_ue->suci, served_tai_index);

    /* Store UE specific information */
    if (registration_request->presencemask &
        OGS_NAS_5GS_REGISTRATION_REQUEST_LAST_VISITED_REGISTERED_TAI_PRESENT) {
        ogs_nas_5gs_tai_t *last_visited_registered_tai = 
            &registration_request->last_visited_registered_tai;

        ogs_nas_to_plmn_id(&amf_ue->last_visited_plmn_id,
            &last_visited_registered_tai->nas_plmn_id);
        ogs_debug("[%s]    Visited_PLMN_ID:%06x", amf_ue->suci,
                ogs_plmn_id_hexdump(&amf_ue->last_visited_plmn_id));
    }

    if (registration_request->presencemask &
            OGS_NAS_5GS_REGISTRATION_REQUEST_5GMM_CAPABILITY_PRESENT) {
        ogs_nas_5gmm_capability_t *gmm_capability =
            &registration_request->gmm_capability;

        amf_ue->gmm_capability.lte_positioning_protocol_capability
            = gmm_capability->lte_positioning_protocol_capability;
        amf_ue->gmm_capability.ho_attach = gmm_capability->ho_attach;
        amf_ue->gmm_capability.s1_mode = gmm_capability->s1_mode;
            
        ogs_debug("[%s]    5GMM Capability:[LPP:%d, HO_ATTACH:%d, S1_MODE:%d]",
            amf_ue->suci,
            amf_ue->gmm_capability.lte_positioning_protocol_capability,
            amf_ue->gmm_capability.ho_attach,
            amf_ue->gmm_capability.s1_mode);
    }

    if (registration_request->presencemask &
            OGS_NAS_5GS_REGISTRATION_REQUEST_UE_SECURITY_CAPABILITY_PRESENT) {
        memcpy(&amf_ue->ue_security_capability,
                &registration_request->ue_security_capability,
                registration_request->ue_security_capability.length +
                sizeof(registration_request->ue_security_capability.length));
    }

    if (registration_request->presencemask &
            OGS_NAS_5GS_REGISTRATION_REQUEST_S1_UE_NETWORK_CAPABILITY_PRESENT) {
        memcpy(&amf_ue->ue_network_capability,
                &registration_request->s1_ue_network_capability,
                registration_request->s1_ue_network_capability.length +
                sizeof(registration_request->s1_ue_network_capability.length));
    }

    if (amf_selected_int_algorithm(amf_ue) ==
            OGS_NAS_SECURITY_ALGORITHMS_NIA0) {
        ogs_error("[%s] [UE:0x%x:0x%x], NEA0 can be used in Encrypt[0x%x], "
            "but Integrity[0x%x] cannot be bypassed with NIA0", amf_ue->suci,
            ue_security_capability->nea, ue_security_capability->nia,
            amf_selected_enc_algorithm(amf_ue), 
            amf_selected_int_algorithm(amf_ue));
        nas_5gs_send_registration_reject(amf_ue,
            OGS_5GMM_CAUSE_UE_SECURITY_CAPABILITIES_MISMATCH);
        return OGS_ERROR;
    }

    return OGS_OK;
}

int gmm_handle_registration_update(amf_ue_t *amf_ue,
        ogs_nas_5gs_registration_request_t *registration_request)
{
    amf_sess_t *sess = NULL;
    uint16_t psimask = 0;
    bool handled = false;

    amf_nsmf_pdu_session_update_sm_context_param_t param;
    ogs_nas_uplink_data_status_t *uplink_data_status = NULL;

    ogs_assert(amf_ue);
    ogs_assert(registration_request);

    uplink_data_status = &registration_request->uplink_data_status;
    ogs_assert(uplink_data_status);

    if ((registration_request->presencemask &
            OGS_NAS_5GS_REGISTRATION_REQUEST_UPLINK_DATA_STATUS_PRESENT) == 0) {
        ogs_error("No Update data status");
        return OGS_ERROR;
    }

    psimask = 0;
    psimask |= uplink_data_status->psi << 8;
    psimask |= uplink_data_status->psi >> 8;

    handled = false;
    ogs_list_for_each(&amf_ue->sess_list, sess) {
        if (psimask & (1 << sess->psi)) {
            /* UPDATE_UpCnxState - UE: ACTIVATING, SMF: DEACTIVATED */
            sess->ueUpCnxState = OpenAPI_up_cnx_state_ACTIVATING;
            sess->smfUpCnxState = OpenAPI_up_cnx_state_DEACTIVATED;

            memset(&param, 0, sizeof(param));
            param.upCnxState = sess->ueUpCnxState;
            amf_sess_sbi_discover_and_send(
                    OpenAPI_nf_type_SMF, sess, &param,
                    amf_nsmf_pdu_session_build_update_sm_context);
            handled = true;
        }
    }

    if (handled == false) {
        ogs_error("Cannot find PSI[0x%x]", uplink_data_status->psi);
        return OGS_ERROR;
    }

    return OGS_OK;
}

int gmm_handle_authentication_response(amf_ue_t *amf_ue,
        ogs_nas_5gs_authentication_response_t *authentication_response)
{
    ogs_nas_authentication_response_parameter_t
        *authentication_response_parameter = NULL;
    uint8_t hxres_star[OGS_MAX_RES_LEN];

    ogs_assert(amf_ue);
    ogs_assert(authentication_response);

    authentication_response_parameter = &authentication_response->
                authentication_response_parameter;

    ogs_debug("[%s] Authentication response", amf_ue->suci);

    CLEAR_AMF_UE_TIMER(amf_ue->t3560);

    if (authentication_response_parameter->length != OGS_MAX_RES_LEN) {
        ogs_error("[%s] Invalid length [%d]",
                amf_ue->suci, authentication_response_parameter->length);
        return OGS_ERROR;
    }

    ogs_kdf_hxres_star(
            amf_ue->rand, authentication_response_parameter->res, hxres_star);

    if (memcmp(hxres_star, amf_ue->hxres_star, OGS_MAX_RES_LEN) != 0) {
        ogs_log_hexdump(OGS_LOG_WARN,
                authentication_response_parameter->res,
                authentication_response_parameter->length);
        ogs_log_hexdump(OGS_LOG_WARN, hxres_star, OGS_MAX_RES_LEN);
        ogs_log_hexdump(OGS_LOG_WARN,
                amf_ue->hxres_star, OGS_MAX_RES_LEN);
        return OGS_ERROR;
    }

    memcpy(amf_ue->xres_star, authentication_response_parameter->res,
            authentication_response_parameter->length);

    amf_ue_sbi_discover_and_send(OpenAPI_nf_type_AUSF, amf_ue, NULL,
            amf_nausf_auth_build_authenticate_confirmation);

    return OGS_OK;
}

int gmm_handle_identity_response(amf_ue_t *amf_ue,
        ogs_nas_5gs_identity_response_t *identity_response)
{
    ran_ue_t *ran_ue = NULL;

    ogs_nas_5gs_mobile_identity_t *mobile_identity = NULL;
    ogs_nas_5gs_mobile_identity_header_t *mobile_identity_header = NULL;

    ogs_assert(identity_response);

    ogs_assert(amf_ue);
    ran_ue = amf_ue->ran_ue;
    ogs_assert(ran_ue);

    mobile_identity = &identity_response->mobile_identity;

    if (!mobile_identity->length || !mobile_identity->buffer) {
        ogs_error("No Mobile Identity");
        return OGS_ERROR;
    }

    mobile_identity_header =
            (ogs_nas_5gs_mobile_identity_header_t *)mobile_identity->buffer;

    if (mobile_identity_header->type == OGS_NAS_5GS_MOBILE_IDENTITY_SUCI) {
        amf_ue_set_suci(amf_ue, mobile_identity);
        ogs_debug("[%s]    SUCI", amf_ue->suci);
    } else {
        ogs_error("Not supported Identity type[%d]",
                mobile_identity_header->type);
    }

    return OGS_OK;
}

int gmm_handle_deregistration_request(amf_ue_t *amf_ue,
        ogs_nas_5gs_deregistration_request_from_ue_t *deregistration_request)
{
    ogs_nas_de_registration_type_t *de_registration_type = NULL;

    ogs_assert(amf_ue);
    ogs_assert(deregistration_request);

    de_registration_type = &deregistration_request->de_registration_type;

    ogs_debug("[%s] Deregistration request", amf_ue->supi);

    /* Set 5GS Attach Type */
    memcpy(&amf_ue->nas.de_registration,
            de_registration_type, sizeof(ogs_nas_de_registration_type_t));
    amf_ue->nas.message_type = OGS_NAS_5GS_DEREGISTRATION_REQUEST;
    amf_ue->nas.tsc = de_registration_type->tsc;
    amf_ue->nas.ksi = de_registration_type->ksi;
    ogs_debug("[%s]    OGS_NAS_5GS TYPE[%d] TSC[%d] KSI[%d] "
            "DEREGISTRATION[0x%x]",
            amf_ue->suci, amf_ue->nas.message_type,
            amf_ue->nas.tsc, amf_ue->nas.ksi, amf_ue->nas.data);

    if (deregistration_request->de_registration_type.switch_off)
        ogs_debug("    Switch-Off");

    amf_send_delete_session_or_de_register(amf_ue);

    return OGS_OK;
}

int gmm_handle_service_request(amf_ue_t *amf_ue,
        ogs_nas_5gs_service_request_t *service_request)
{
    amf_sess_t *sess = NULL;
    ogs_nas_key_set_identifier_t *ngksi = NULL;
    ogs_nas_uplink_data_status_t *uplink_data_status = NULL;
    uint16_t psimask = 0;
    bool need_to_activating = false;

    ogs_assert(amf_ue);

    ngksi = &service_request->ngksi;
    ogs_assert(ngksi);
    uplink_data_status = &service_request->uplink_data_status;

    amf_ue->nas.message_type = OGS_NAS_5GS_SERVICE_REQUEST;
    amf_ue->nas.tsc = ngksi->tsc;
    amf_ue->nas.ksi = ngksi->value;
    ogs_debug("[%s]    OGS_NAS_5GS TYPE[%d] TSC[%d] KSI[%d] SERVICE[0x%x]",
            amf_ue->suci, amf_ue->nas.message_type,
            amf_ue->nas.tsc, amf_ue->nas.ksi, amf_ue->nas.data);

    /*
     * REGISTRATION_REQUEST
     *   Clear EBI generator
     *   Clear Timer and Message
     *
     * TAU_REQUEST
     *   Clear Timer and Message
     *
     * SERVICE_REQUEST
     *   Clear Timer and Message
     *
     * EXTENDED_SERVICE_REQUEST
     *   Clear Timer and Message
     */
    CLEAR_AMF_UE_ALL_TIMERS(amf_ue);

    if (SECURITY_CONTEXT_IS_VALID(amf_ue)) {
        ogs_kdf_kgnb_and_kn3iwf(
                amf_ue->kamf, amf_ue->ul_count.i32,
                amf_ue->nas.access_type, amf_ue->kgnb);
        ogs_kdf_nh_gnb(amf_ue->kamf, amf_ue->kgnb, amf_ue->nh);
        amf_ue->nhcc = 1;
    }

    ogs_debug("[%s]    5G-S_GUTI[AMF_ID:0x%x,M_TMSI:0x%x]",
        AMF_UE_HAVE_SUCI(amf_ue) ? amf_ue->suci : "Unknown ID",
        ogs_amf_id_hexdump(&amf_ue->guti.amf_id), amf_ue->guti.m_tmsi);

    if (!AMF_UE_HAVE_SUCI(amf_ue)) {
        ogs_debug("Service request : Unknown UE");
        nas_5gs_send_service_reject(amf_ue,
            OGS_5GMM_CAUSE_UE_IDENTITY_CANNOT_BE_DERIVED_BY_THE_NETWORK, false);
        return OGS_ERROR;
    }

    if (!SECURITY_CONTEXT_IS_VALID(amf_ue)) {
        ogs_debug("[%s] No Security Context", amf_ue->supi);
        nas_5gs_send_service_reject(amf_ue,
            OGS_5GMM_CAUSE_UE_IDENTITY_CANNOT_BE_DERIVED_BY_THE_NETWORK, false);
        return OGS_ERROR;
    }

    if (!SESSION_CONTEXT_IS_AVAILABLE(amf_ue)) {
        ogs_debug("[%s] No Session Context", amf_ue->supi);
        nas_5gs_send_service_reject(amf_ue,
            OGS_5GMM_CAUSE_UE_IDENTITY_CANNOT_BE_DERIVED_BY_THE_NETWORK, false);
        return OGS_ERROR;
    }

    if ((service_request->presencemask &
            OGS_NAS_5GS_SERVICE_REQUEST_UPLINK_DATA_STATUS_PRESENT) == 0) {
        ogs_error("No Update data status");
        nas_5gs_send_service_reject(amf_ue,
            OGS_5GMM_CAUSE_SEMANTICALLY_INCORRECT_MESSAGE, false);
        return OGS_ERROR;
    }

    psimask = 0;
    psimask |= uplink_data_status->psi << 8;
    psimask |= uplink_data_status->psi >> 8;

    /*
     * TS24.501
     * 5.6.1.5 Service request procedure not accepted by the network
     *
     * If the AMF needs to initiate PDU session status synchronisation
     * or a PDU session status IE was included in the SERVICE REQUEST message,
     * the AMF shall include a PDU session status IE in the SERVICE REJECT
     * message to indicate which PDU sessions associated with the access type
     * the SERVICE REJECT message is sent over are active in the AMF.
     * If the PDU session status IE is included in the SERVICE REJECT message
     * and if the message is integrity protected, then the UE shall perform
     * a local release of all those PDU sessions which are active
     * on the UE side associated with the access type the SERVICE REJECT
     * message is sent over, but are indicated by the AMF as being inactive.
     */
    need_to_activating = false;
    ogs_list_for_each(&amf_ue->sess_list, sess) {
        if (psimask & (1 << sess->psi)) {
            if (sess->smfUpCnxState == OpenAPI_up_cnx_state_DEACTIVATED) {
                need_to_activating = true;

            } else if (sess->smfUpCnxState == OpenAPI_up_cnx_state_ACTIVATED) {
                nas_5gs_send_service_reject(amf_ue,
                    OGS_5GMM_CAUSE_UE_IDENTITY_CANNOT_BE_DERIVED_BY_THE_NETWORK,
                    true);
                return OGS_ERROR;

            } else if (sess->smfUpCnxState == OpenAPI_up_cnx_state_ACTIVATING) {
                ogs_warn("Service request has already been received");
                /* Ignore */
            }
        }
    }

    if (need_to_activating) {
        ogs_list_for_each(&amf_ue->sess_list, sess) {
            if (psimask & (1 << sess->psi)) {
                if (sess->smfUpCnxState == OpenAPI_up_cnx_state_DEACTIVATED) {
                    amf_nsmf_pdu_session_update_sm_context_param_t param;

                    /* UPDATE_UpCnxState - ACTIVATING */
                    sess->ueUpCnxState = OpenAPI_up_cnx_state_ACTIVATING;

                    memset(&param, 0, sizeof(param));
                    param.upCnxState = OpenAPI_up_cnx_state_ACTIVATING;
                    amf_sess_sbi_discover_and_send(
                            OpenAPI_nf_type_SMF, sess, &param,
                            amf_nsmf_pdu_session_build_update_sm_context);
                }
            }
        }
    }

    return OGS_OK;
}

#if 0
int gmm_handle_tau_request(amf_ue_t *amf_ue,
        ogs_nas_5gs_tracking_area_update_request_t *tau_request)
{
    int served_tai_index = 0;

    ogs_nas_5gs_mobile_identity_guti_t *5gs_mobile_identity_guti = NULL;
    ogs_nas_5gs_guti_t nas_guti;

    ogs_nas_5gs_update_type_t *5gs_update_type =
                    &tau_request->5gs_update_type;
    ogs_nas_5gs_mobile_identity_t *5gs_mobile_identity =
                    &tau_request->old_guti;
    ran_ue_t *ran_ue = NULL;

    ogs_assert(amf_ue);
    ran_ue = amf_ue->ran_ue;
    ogs_assert(ran_ue);

    /* Set 5GS Update Type */
    memcpy(&amf_ue->nas.update, 5gs_update_type,
            sizeof(ogs_nas_5gs_update_type_t));
    amf_ue->nas.message_type = AMF_5GS_TYPE_TAU_REQUEST;
    amf_ue->nas.ksi = 5gs_update_type->nas_key_set_identifier;
    ogs_debug("    OGS_NAS_5GS TYPE[%d] KSI[%d] UPDATE[0x%x]",
            amf_ue->nas.message_type, amf_ue->nas.ksi,
            amf_ue->nas.data);
    
    /*
     * REGISTRATION_REQUEST
     *   Clear EBI generator
     *   Clear Timer and Message
     *
     * TAU_REQUEST
     *   Clear Timer and Message
     *
     * SERVICE_REQUEST
     *   Clear Timer and Message
     *
     * EXTENDED_SERVICE_REQUEST
     *   Clear Timer and Message
     */
    CLEAR_AMF_UE_ALL_TIMERS(amf_ue);

    CLEAR_SERVICE_INDICATOR(amf_ue);
    if (BEARER_CONTEXT_IS_ACTIVE(amf_ue))
        ogs_debug("    Bearer-Active");
    else
        ogs_debug("    Bearer-Inactive");

    if (amf_ue->nas.update.active_flag)
        ogs_debug("    Active flag");
    else
        ogs_debug("    No Active flag");

    ogs_debug("    OLD TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac);
    ogs_debug("    OLD NR_CGI[PLMN_ID:%06x,CELL_ID:%d]",
            ogs_plmn_id_hexdump(&amf_ue->e_cgi.plmn_id), amf_ue->e_cgi.cell_id);
    ogs_debug("    TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&ran_ue->saved.tai.plmn_id),
            ran_ue->saved.tai.tac);
    ogs_debug("    NR_CGI[PLMN_ID:%06x,CELL_ID:%d]",
            ogs_plmn_id_hexdump(&ran_ue->saved.e_cgi.plmn_id),
            ran_ue->saved.e_cgi.cell_id);

    /* Copy TAI and ECGI from ran_ue */
    memcpy(&amf_ue->tai, &ran_ue->saved.tai, sizeof(ogs_5gs_tai_t));
    memcpy(&amf_ue->e_cgi, &ran_ue->saved.e_cgi, sizeof(ogs_e_cgi_t));

    /* Check TAI */
    served_tai_index = amf_find_served_tai(&amf_ue->tai);
    if (served_tai_index < 0) {
        /* Send TAU reject */
        ogs_warn("Cannot find Served TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac);
        nas_5gs_send_tau_reject(amf_ue, EMM_CAUSE_TRACKING_AREA_NOT_ALLOWED);
        return OGS_ERROR;
    }
    ogs_debug("    SERVED_TAI_INDEX[%d]", served_tai_index);

    /* Store UE specific information */
    if (tau_request->presencemask &
        OGS_NAS_5GS_TRACKING_AREA_UPDATE_REQUEST_LAST_VISITED_REGISTERED_TAI_PRESENT) {
        ogs_nas_5gs_tai_t *last_visited_registered_tai = 
            &tau_request->last_visited_registered_tai;

        ogs_nas_to_plmn_id(&amf_ue->last_visited_plmn_id,
                &last_visited_registered_tai->nas_plmn_id);
        ogs_debug("    Visited_PLMN_ID:%06x",
                ogs_plmn_id_hexdump(&amf_ue->last_visited_plmn_id));
    } 

    if (tau_request->presencemask &
            OGS_NAS_5GS_TRACKING_AREA_UPDATE_REQUEST_UE_NETWORK_CAPABILITY_PRESENT) {
        memcpy(&amf_ue->ue_network_capability, 
                &tau_request->ue_network_capability,
                sizeof(tau_request->ue_network_capability));
    }

    if (tau_request->presencemask &
            OGS_NAS_5GS_TRACKING_AREA_UPDATE_REQUEST_MS_NETWORK_CAPABILITY_PRESENT) {
        memcpy(&amf_ue->ms_network_capability, 
                &tau_request->ms_network_capability,
                sizeof(tau_request->ms_network_capability));
    }

    /* TODO: 
     *   1) Consider if AMF is changed or not.
     *   2) Consider if SGW is changed or not.
     */
    switch (5gs_mobile_identity->imsi.type) {
    case OGS_NAS_5GS_MOBILE_IDENTITY_GUTI:
        5gs_mobile_identity_guti = &5gs_mobile_identity->guti;

        nas_guti.nas_plmn_id = 5gs_mobile_identity_guti->nas_plmn_id;
        nas_guti.amf_gid = 5gs_mobile_identity_guti->amf_gid;
        nas_guti.amf_code = 5gs_mobile_identity_guti->amf_code;
        nas_guti.m_tmsi = 5gs_mobile_identity_guti->m_tmsi;

        ogs_debug("    GUTI[G:%d,C:%d,M_TMSI:0x%x] IMSI:[%s]",
                nas_guti.amf_gid,
                nas_guti.amf_code,
                nas_guti.m_tmsi,
                AMF_UE_HAVE_IMSI(amf_ue) 
                    ? amf_ue->imsi_bcd : "Unknown");
        break;
    default:
        ogs_warn("Not implemented[%d]", 
                5gs_mobile_identity->imsi.type);
        
        return OGS_OK;
    }

    return OGS_OK;
}

int gmm_handle_extended_service_request(amf_ue_t *amf_ue,
        ogs_nas_5gs_extended_service_request_t *extended_service_request)
{
    int served_tai_index = 0;

    ogs_nas_service_type_t *service_type =
        &extended_service_request->service_type;
    ogs_nas_mobile_identity_t *mobile_identity =
        &extended_service_request->m_tmsi;
    ogs_nas_mobile_identity_tmsi_t *mobile_identity_tmsi = NULL;
    ran_ue_t *ran_ue = NULL;

    ogs_assert(amf_ue);
    ran_ue = amf_ue->ran_ue;
    ogs_assert(ran_ue);

    /* Set Service Type */
    memcpy(&amf_ue->nas.service, service_type,
            sizeof(ogs_nas_service_type_t));
    amf_ue->nas.message_type = AMF_5GS_TYPE_EXTENDED_SERVICE_REQUEST;
    amf_ue->nas.ksi = service_type->nas_key_set_identifier;
    ogs_debug("    OGS_NAS_5GS TYPE[%d] KSI[%d] SERVICE[0x%x]",
            amf_ue->nas.message_type, amf_ue->nas.ksi, amf_ue->nas.value);
    
    /*
     * REGISTRATION_REQUEST
     *   Clear EBI generator
     *   Clear Timer and Message
     *
     * TAU_REQUEST
     *   Clear Timer and Message
     *
     * SERVICE_REQUEST
     *   Clear Timer and Message
     *
     * EXTENDED_SERVICE_REQUEST
     *   Clear Timer and Message
     */
    CLEAR_AMF_UE_ALL_TIMERS(amf_ue);

    ogs_debug("    OLD TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac);
    ogs_debug("    OLD NR_CGI[PLMN_ID:%06x,CELL_ID:%d]",
            ogs_plmn_id_hexdump(&amf_ue->e_cgi.plmn_id), amf_ue->e_cgi.cell_id);
    ogs_debug("    TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&ran_ue->saved.tai.plmn_id),
            ran_ue->saved.tai.tac);
    ogs_debug("    NR_CGI[PLMN_ID:%06x,CELL_ID:%d]",
            ogs_plmn_id_hexdump(&ran_ue->saved.e_cgi.plmn_id),
            ran_ue->saved.e_cgi.cell_id);

    /* Copy TAI and ECGI from ran_ue */
    memcpy(&amf_ue->tai, &ran_ue->saved.tai, sizeof(ogs_5gs_tai_t));
    memcpy(&amf_ue->e_cgi, &ran_ue->saved.e_cgi, sizeof(ogs_e_cgi_t));

    /* Check TAI */
    served_tai_index = amf_find_served_tai(&amf_ue->tai);
    if (served_tai_index < 0) {
        /* Send TAU reject */
        ogs_warn("Cannot find Served TAI[PLMN_ID:%06x,TAC:%d]",
            ogs_plmn_id_hexdump(&amf_ue->tai.plmn_id), amf_ue->tai.tac);
        nas_5gs_send_tau_reject(amf_ue, EMM_CAUSE_TRACKING_AREA_NOT_ALLOWED);
        return OGS_ERROR;
    }
    ogs_debug("    SERVED_TAI_INDEX[%d]", served_tai_index);

    switch(mobile_identity->tmsi.type) {
    case OGS_NAS_MOBILE_IDENTITY_TMSI:
        mobile_identity_tmsi = &mobile_identity->tmsi;

        ogs_debug("    M-TMSI:[0x%x] IMSI:[%s]",
                mobile_identity_tmsi->tmsi,
                AMF_UE_HAVE_IMSI(amf_ue) ? amf_ue->imsi_bcd : "Unknown");
        break;
    default:
        ogs_error("Unknown TMSI type [%d]", mobile_identity->tmsi.type);
        break;
    }

    return OGS_OK;
}
#endif

int gmm_handle_security_mode_complete(amf_ue_t *amf_ue,
    ogs_nas_5gs_security_mode_complete_t *security_mode_complete)
{
    ogs_nas_5gs_mobile_identity_t *imeisv = NULL;
    ogs_nas_mobile_identity_imeisv_t *mobile_identity_imeisv = NULL;

    ogs_assert(amf_ue);
    ogs_assert(security_mode_complete);

    if (security_mode_complete->presencemask &
        OGS_NAS_5GS_SECURITY_MODE_COMMAND_IMEISV_REQUEST_PRESENT) {

        imeisv = &security_mode_complete->imeisv;
        ogs_assert(imeisv);
        mobile_identity_imeisv =
            (ogs_nas_mobile_identity_imeisv_t *)imeisv->buffer;
        ogs_assert(mobile_identity_imeisv);

        switch (mobile_identity_imeisv->type) {
        case OGS_NAS_5GS_MOBILE_IDENTITY_IMEISV:
            memcpy(&amf_ue->nas_mobile_identity_imeisv,
                mobile_identity_imeisv, imeisv->length);
            ogs_nas_imeisv_to_bcd(mobile_identity_imeisv, imeisv->length,
                    amf_ue->imeisv_bcd);
            ogs_bcd_to_buffer(amf_ue->imeisv_bcd,
                    amf_ue->imeisv, &amf_ue->imeisv_len);
            if (amf_ue->pei)
                ogs_free(amf_ue->pei);
            amf_ue->pei = ogs_msprintf("imeisv-%s", amf_ue->imeisv_bcd);
            break;
        default:
            ogs_warn("[%s] Invalid IMEISV Type [%d]",
                    amf_ue->supi, mobile_identity_imeisv->type);
            break;

        }
    }

    return OGS_OK;
}

int gmm_handle_ul_nas_transport(amf_ue_t *amf_ue,
        ogs_nas_5gs_ul_nas_transport_t *ul_nas_transport)
{
    ogs_nas_payload_container_type_t *payload_container_type = NULL;
    ogs_nas_payload_container_t *payload_container = NULL;
    ogs_nas_pdu_session_identity_2_t *pdu_session_id = NULL;
    ogs_nas_s_nssai_t *nas_s_nssai = NULL;
    ogs_s_nssai_t *selected_s_nssai = NULL;
    ogs_nas_dnn_t *dnn = NULL;

    amf_sess_t *sess = NULL;

    ogs_assert(amf_ue);
    ogs_assert(ul_nas_transport);

    payload_container_type = &ul_nas_transport->payload_container_type;
    ogs_assert(payload_container_type);
    payload_container = &ul_nas_transport->payload_container;
    ogs_assert(payload_container);

    if (!payload_container_type->value) {
        ogs_error("[%s] No Payload container type", amf_ue->supi);
        return OGS_ERROR;
    }

    if (!payload_container->length) {
        ogs_error("[%s] No Payload container length", amf_ue->supi);
        return OGS_ERROR;
    }

    if (!payload_container->buffer) {
        ogs_error("[%s] No Payload container buffer", amf_ue->supi);
        return OGS_ERROR;
    }

    switch (payload_container_type->value) {
    case OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION:
        pdu_session_id = &ul_nas_transport->pdu_session_id;
        ogs_assert(pdu_session_id);
        nas_s_nssai = &ul_nas_transport->s_nssai;
        ogs_assert(nas_s_nssai);
        dnn = &ul_nas_transport->dnn;
        ogs_assert(dnn);

        if ((ul_nas_transport->presencemask &
                OGS_NAS_5GS_UL_NAS_TRANSPORT_PDU_SESSION_ID_PRESENT) == 0) {
            ogs_error("[%s] No PDU session ID", amf_ue->supi);
            return OGS_ERROR;
        }

        pdu_session_id = &ul_nas_transport->pdu_session_id;
        if (*pdu_session_id == OGS_NAS_PDU_SESSION_IDENTITY_UNASSIGNED) {
            ogs_error("[%s] PDU session identity is unassigned", amf_ue->supi);
            return OGS_ERROR;
        }

        sess = amf_sess_find_by_psi(amf_ue, *pdu_session_id);
        if (!sess) {
            sess = amf_sess_add(amf_ue, *pdu_session_id);
            ogs_assert(sess);
        }

        if (sess->payload_container)
            ogs_pkbuf_free(sess->payload_container);

        sess->payload_container_type = payload_container_type->value;
        sess->payload_container =
            ogs_pkbuf_alloc(NULL, payload_container->length);
        ogs_assert(sess->payload_container);
        ogs_pkbuf_put_data(sess->payload_container,
                payload_container->buffer, payload_container->length);

        if (ul_nas_transport->presencemask &
                OGS_NAS_5GS_UL_NAS_TRANSPORT_S_NSSAI_PRESENT) {
            ogs_s_nssai_t s_nssai;
            s_nssai.sst = nas_s_nssai->sst;
            if (nas_s_nssai->length > 1)
                s_nssai.sd = ogs_be24toh(nas_s_nssai->sd);
            else
                s_nssai.sd.v = OGS_S_NSSAI_NO_SD_VALUE;
            selected_s_nssai = amf_find_s_nssai(&amf_ue->tai.plmn_id, &s_nssai);
        }

        if (!selected_s_nssai) {
            ogs_warn("No S_NSSAI : Set default S_NSSAI using AMF config");
            selected_s_nssai = &amf_self()->plmn_support[0].s_nssai[0];
            ogs_assert(selected_s_nssai);
        }

        memcpy(&sess->s_nssai, selected_s_nssai, sizeof(ogs_s_nssai_t));

        if (ul_nas_transport->presencemask &
                OGS_NAS_5GS_UL_NAS_TRANSPORT_DNN_PRESENT) {
            if (sess->dnn)
                ogs_free(dnn);
            sess->dnn = ogs_strdup(dnn->value);
        }

        amf_sess_sbi_discover_and_send(
                OpenAPI_nf_type_SMF, sess, NULL,
                amf_nsmf_pdu_session_build_create_sm_context);
        break;

    default:
        ogs_error("[%s] Unknown Payload container type [%d]",
            amf_ue->supi, payload_container_type->value);
        return OGS_ERROR;
    }

    return OGS_OK;
}