/*
 * 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
 */

/*****************************************************************************
Source      EpsBearerContextDeactivation.c

Version     0.1

Date        2013/05/22

Product     NAS stack

Subsystem   EPS Session Management

Author      Frederic Maurel

Description Defines the EPS bearer context deactivation ESM procedure
        executed by the Non-Access Stratum.

        The purpose of the EPS bearer context deactivation procedure
        is to deactivate an EPS bearer context or disconnect from a
        PDN by deactivating all EPS bearer contexts to the PDN.
        The EPS bearer context deactivation procedure is initiated
        by the network, and it may be triggered by the UE by means
        of the UE requested bearer resource modification procedure
        or UE requested PDN disconnect procedure.

*****************************************************************************/

#include "esm_proc.h"
#include "commonDef.h"
#include "nas_log.h"

#include "emmData.h"
#include "esmData.h"
#include "esm_cause.h"
#include "esm_ebr.h"
#include "esm_ebr_context.h"

#include "esm_main.h"

#include "emm_sap.h"
#include "esm_sap.h"

/****************************************************************************/
/****************  E X T E R N A L    D E F I N I T I O N S  ****************/
/****************************************************************************/

/****************************************************************************/
/*******************  L O C A L    D E F I N I T I O N S  *******************/
/****************************************************************************/

/*
 * --------------------------------------------------------------------------
 * Internal data handled by the EPS bearer context deactivation procedure
 * in the UE
 * --------------------------------------------------------------------------
 */
static int _eps_bearer_release(nas_user_t *user, int ebi, int *pid, int *bid);


/****************************************************************************/
/******************  E X P O R T E D    F U N C T I O N S  ******************/
/****************************************************************************/


/*
 * --------------------------------------------------------------------------
 *  EPS bearer context deactivation procedure executed by the UE
 * --------------------------------------------------------------------------
 */
/****************************************************************************
 **                                                                        **
 ** Name:    esm_proc_eps_bearer_context_deactivate()                  **
 **                                                                        **
 ** Description: Locally releases the EPS bearer context identified by the **
 **      given EPS bearer identity, without peer-to-peer signal-   **
 **      ling between the UE and the MME, or checks whether the UE **
 **      has an EPS bearer context with specified EPS bearer iden- **
 **      tity activated.                                           **
 **                                                                        **
 ** Inputs:  is local:  true if the EPS bearer context has to be   **
 **             locally released without peer-to-peer si-  **
 **             gnalling between the UE and the MME        **
 **      ebi:       EPS bearer identity of the EPS bearer con- **
 **             text to be deactivated                     **
 **                                                                        **
 ** Outputs:     pid:       Identifier of the PDN connection the EPS   **
 **             bearer belongs to                          **
 **      bid:       Identifier of the released EPS bearer con- **
 **             text entry                                 **
 **      Return:    RETURNok, RETURNerror                      **
 **      Others:    None                                       **
 **                                                                        **
 ***************************************************************************/
int esm_proc_eps_bearer_context_deactivate(nas_user_t *user, bool is_local, int ebi,
    int *pid, int *bid)
{
  LOG_FUNC_IN;

  int rc = RETURNerror;
  int i;
  esm_data_t *esm_data = user->esm_data;
  if (is_local) {
    if (ebi != ESM_SAP_ALL_EBI) {
      /* Locally release the EPS bearer context */
      rc = _eps_bearer_release(user, ebi, pid, bid);
    } else {
      /* Locally release all the EPS bearer contexts */
      *bid = 0;

      for (*pid = 0; *pid < ESM_DATA_PDN_MAX; (*pid)++) {
        if (esm_data->pdn[*pid].data) {
          rc = _eps_bearer_release(user, ESM_EBI_UNASSIGNED, pid, bid);

          if (rc != RETURNok) {
            break;
          }
        }
      }
    }

    LOG_FUNC_RETURN (rc);
  }

  LOG_TRACE(WARNING, "ESM-PROC  - EPS bearer context deactivation (ebi=%d)",
            ebi);

  if (*pid < ESM_DATA_PDN_MAX) {
    if (esm_data->pdn[*pid].pid != *pid) {
      LOG_TRACE(ERROR, "ESM-PROC  - PDN connection identifier %d "
                "is not valid", *pid);
    } else if (esm_data->pdn[*pid].data == NULL) {
      LOG_TRACE(ERROR, "ESM-PROC  - PDN connection %d has not been "
                "allocated", *pid);
    } else if (!esm_data->pdn[*pid].is_active) {
      LOG_TRACE(WARNING, "ESM-PROC  - PDN connection %d is not active",
                *pid);
    } else {
      esm_pdn_t *pdn = esm_data->pdn[*pid].data;

      for (i = 0; i < pdn->n_bearers; i++) {
        if (pdn->bearer[i]->ebi != ebi) {
          continue;
        }

        /* The EPS bearer context to be released is valid */
        rc = RETURNok;
      }
    }
  }

  LOG_FUNC_RETURN (rc);
}

/****************************************************************************
 **                                                                        **
 ** Name:    esm_proc_eps_bearer_context_deactivate_request()          **
 **                                                                        **
 ** Description: Deletes the EPS bearer context identified by the EPS bea- **
 **      rer identity upon receipt of the DEACTIVATE EPS BEARER    **
 **      CONTEXT REQUEST message.                                  **
 **                                                                        **
 ** Inputs:  ebi:       EPS bearer identity                        **
 **      Others:    None                                       **
 **                                                                        **
 ** Outputs:     esm_cause: Cause code returned upon ESM procedure     **
 **             failure                                    **
 **      Return:    RETURNok, RETURNerror                      **
 **      Others:    None                                       **
 **                                                                        **
 ***************************************************************************/
int esm_proc_eps_bearer_context_deactivate_request(nas_user_t *user, int ebi, int *esm_cause)
{
  LOG_FUNC_IN;

  int pid, bid;
  int rc = RETURNok;
  esm_data_t *esm_data = user->esm_data;
  bid = 0;
  pid = 0;

  LOG_TRACE(INFO, "ESM-PROC  - EPS bearer context deactivation "
            "requested by the network (ebi=%d)", ebi);

  /* Release the EPS bearer context entry */
  if (esm_ebr_context_release(user, ebi, &pid, &bid) == ESM_EBI_UNASSIGNED) {
    LOG_TRACE(WARNING, "ESM-PROC  - Failed to release EPS bearer context");
    *esm_cause = ESM_CAUSE_PROTOCOL_ERROR;
    LOG_FUNC_RETURN (RETURNerror);
  }

  if (bid == 0) {
    /* The EPS bearer identity is that of the default bearer assigned to
     * the PDN connection */
    if (*esm_cause == ESM_CAUSE_REACTIVATION_REQUESTED) {
      esm_sap_t esm_sap;
      bool active = false;

      /* 3GPP TS 24.301, section 6.4.4.3
       * The UE should re-initiate the UE requested PDN connectivity
       * procedure for the APN associated to the PDN it was connected
       * to in order to reactivate the EPS bearer context
       */
      LOG_TRACE(WARNING, "ESM-PROC  - The network requests PDN "
                "connection reactivation");

      /* Get PDN context parameters */
      rc = esm_main_get_pdn(esm_data, pid + 1, &esm_sap.data.pdn_connect.pdn_type,
                            &esm_sap.data.pdn_connect.apn,
                            &esm_sap.data.pdn_connect.is_emergency,
                            &active);

      if (rc != RETURNerror) {
        if (active) {
          LOG_TRACE(ERROR, "ESM-PROC  - Connectivity to APN %s "
                    "has not been deactivated",
                    esm_sap.data.pdn_connect.apn);
          *esm_cause = ESM_CAUSE_REQUEST_REJECTED_UNSPECIFIED;
          LOG_FUNC_RETURN (RETURNerror);
        }

        /*
         * Notify ESM to re-initiate PDN connectivity procedure
         */
        esm_sap.primitive = ESM_PDN_CONNECTIVITY_REQ;
        esm_sap.is_standalone = true;
        esm_sap.data.pdn_connect.is_defined = true;
        esm_sap.data.pdn_connect.cid = pid + 1;
        rc = esm_sap_send(user, &esm_sap);
      }
    }
  }

  LOG_FUNC_RETURN (rc);
}

/****************************************************************************
 **                                                                        **
 ** Name:    esm_proc_eps_bearer_context_deactivate_accept()           **
 **                                                                        **
 ** Description: Performs EPS bearer context deactivation procedure accep- **
 **      ted by the UE.                                            **
 **                                                                        **
 **      3GPP TS 24.301, section 6.4.4.3                           **
 **      The UE accepts EPS bearer context deactivation by sending **
 **      DEACTIVATE EPS BEARER CONTEXT ACCEPT message and entering **
 **      the state BEARER CONTEXT INACTIVE.                        **
 **                                                                        **
 ** Inputs:  is_standalone: Should be always true                      **
 **      ebi:       EPS bearer identity                        **
 **      msg:       Encoded ESM message to be sent             **
 **      ue_triggered:  true if the EPS bearer context procedure   **
 **             was triggered by the UE                    **
 **      Others:    None                                       **
 **                                                                        **
 ** Outputs:     None                                                      **
 **      Return:    RETURNok, RETURNerror                      **
 **      Others:    None                                       **
 **                                                                        **
 ***************************************************************************/
int esm_proc_eps_bearer_context_deactivate_accept(nas_user_t *user, bool is_standalone, int ebi,
    OctetString *msg, bool ue_triggered)
{
  LOG_FUNC_IN;

  int rc = RETURNok;
  esm_ebr_data_t *esm_ebr_data = user->esm_ebr_data;
  user_api_id_t *user_api_id = user->user_api_id;

  LOG_TRACE(INFO,"ESM-PROC  - EPS bearer context deactivation accepted");

  if (is_standalone) {
    emm_sap_t emm_sap;
    /*
     * Notity EMM that ESM PDU has to be forwarded to lower layers
     */
    emm_sap.primitive = EMMESM_UNITDATA_REQ;
    emm_sap.u.emm_esm.ueid = user->ueid;
    emm_sap.u.emm_esm.u.data.msg.length = msg->length;
    emm_sap.u.emm_esm.u.data.msg.value = msg->value;
    rc = emm_sap_send(user, &emm_sap);
  }

  if (rc != RETURNerror) {
    /* Set the EPS bearer context state to INACTIVE */
    rc = esm_ebr_set_status(user_api_id, esm_ebr_data, ebi, ESM_EBR_INACTIVE, ue_triggered);

    if (rc != RETURNok) {
      /* The EPS bearer context was already in INACTIVE state */
      LOG_TRACE(WARNING, "ESM-PROC  - EBI %d was already INACTIVE", ebi);
      /* Accept network retransmission of already accepted deactivate
       * EPS bearer context request */
      LOG_FUNC_RETURN (RETURNok);
    }

    /* Release EPS bearer data */
    rc = esm_ebr_release(esm_ebr_data, ebi);
  }

  LOG_FUNC_RETURN (rc);
}


/****************************************************************************/
/*********************  L O C A L    F U N C T I O N S  *********************/
/****************************************************************************/

/*
 * --------------------------------------------------------------------------
 *              Timer handlers
 * --------------------------------------------------------------------------
 */



/*
 * --------------------------------------------------------------------------
 *              UE specific local functions
 * --------------------------------------------------------------------------
 */

/****************************************************************************
 **                                                                        **
 ** Name:    _eps_bearer_release()                                     **
 **                                                                        **
 ** Description: Releases the EPS bearer context identified by the given   **
 **      EPS bearer identity and enters state INACTIVE.            **
 **                                                                        **
 ** Inputs:  ebi:       EPS bearer identity                        **
 **      Others:    None                                       **
 **                                                                        **
 ** Outputs:     pid:       Identifier of the PDN connection the EPS   **
 **             bearer belongs to                          **
 **      bid:       Identifier of the released EPS bearer con- **
 **             text entry                                 **
 **      Return:    RETURNok, RETURNerror                      **
 **      Others:    None                                       **
 **                                                                        **
 ***************************************************************************/
static int _eps_bearer_release(nas_user_t *user, int ebi, int *pid, int *bid)
{
  LOG_FUNC_IN;

  int rc = RETURNerror;
  esm_ebr_data_t *esm_ebr_data = user->esm_ebr_data;
  user_api_id_t *user_api_id = user->user_api_id;

  /* Release the EPS bearer context entry */
  ebi = esm_ebr_context_release(user, ebi, pid, bid);

  if (ebi == ESM_EBI_UNASSIGNED) {
    LOG_TRACE(WARNING, "ESM-PROC  - Failed to release EPS bearer context");
  } else {
    /* Set the EPS bearer context state to INACTIVE */
    rc = esm_ebr_set_status(user_api_id, esm_ebr_data, ebi, ESM_EBR_INACTIVE, false);

    if (rc != RETURNok) {
      /* The EPS bearer context was already in INACTIVE state */
      LOG_TRACE(WARNING, "ESM-PROC  - EBI %d was already INACTIVE", ebi);
    } else {
      /* Release EPS bearer data */
      rc = esm_ebr_release(esm_ebr_data, ebi);

      if (rc != RETURNok) {
        LOG_TRACE(WARNING,
                  "ESM-PROC  - Failed to release EPS bearer data");
      }
    }
  }

  LOG_FUNC_RETURN (rc);
}
