/*******************************************************************************
    OpenAirInterface
    Copyright(c) 1999 - 2014 Eurecom

    OpenAirInterface is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.


    OpenAirInterface 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 OpenAirInterface.The full GNU General Public License is
   included in this distribution in the file called "COPYING". If not,
   see <http://www.gnu.org/licenses/>.

  Contact Information
  OpenAirInterface Admin: openair_admin@eurecom.fr
  OpenAirInterface Tech : openair_tech@eurecom.fr
  OpenAirInterface Dev  : openair4g-devel@eurecom.fr

  Address      : Eurecom, Compus SophiaTech 450, route des chappes, 06451 Biot, France.

 *******************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

#include "conversion.h"
#include "access_restriction.h"

/* TODO: identification of MCC and MNC within an IMSI should be done according
 * to a table that maps MCC to 2 or 3 digits expected...
 * By default we will assume there is only 2 digits for our use.
 */

/* Split a PLMN formed of <MCC><MNC> to mcc and mnc.
 * In case MNC is formed of only two digits a 0 is inserted at the most significant
 * digit.
 * When PLMN is represented using european convention it contains only two digits,
 * while three digits are used in North American Standard.
 * Encoding of PLMN is defined in ITU E.212.
 * @param plmn string either 5 or 6 digits resulting of the concatenation of
 * MCC and MNC.
 */
int split_plmn(uint8_t plmn[3], uint8_t mcc[3], uint8_t mnc[3])
{
  if (plmn == NULL) {
    return -1;
  }

  mcc[0] =  plmn[0] & 0x0F;
  mcc[1] = (plmn[0] & 0xF0) >> 4;
  mcc[2] =  plmn[1] & 0x0F;

  if ((plmn[1] & 0xF0) == 0xF0) {
    /* Only 2 digits case */
    mnc[1] =  plmn[2] & 0x0F;
    mnc[2] = (plmn[2] & 0xF0) >> 4;
    mnc[0] = 0;
  } else {
    mnc[0] =   plmn[2] & 0x0F;
    mnc[1] =  (plmn[2] & 0xF0) >> 4;
    mnc[2] = ((plmn[1] & 0xF0) >> 4);
  }

  return 0;
}

/* Apply restriction (if any) to current 'visited' PLMN for this user.
 * Criterias are based on ODB (operator determined barring), visited PLMN
 * and user PLMN (obtain from IMSI).
 * @param imsi is the user identity formed of MCC.MNC.MSIN (14 or 15 digits long)
 * @param vplmn is the plmn of the cell the UE is currently attached to
 */
#define FORMAT_MCC(mCC) (mCC[0] * 100 + mCC[1] * 10 + mCC[2])
#define FORMAT_MNC(mNC) (mNC[0] * 100 + mNC[1] * 10 + mNC[2])

int apply_access_restriction(char *imsi, uint8_t *vplmn)
{
  uint8_t vmcc[3], vmnc[3];
  uint8_t hmcc[3], hmnc[3];

  uint8_t imsi_hex[15];

  if (bcd_to_hex(imsi_hex, imsi, strlen(imsi)) != 0) {
    fprintf(stderr, "Failed to convert imsi %s to hex representation\n",
            imsi);
    return -1;
  }

  /* There is a problem while converting the PLMN... */
  if (split_plmn(vplmn, vmcc, vmnc) != 0) {
    fprintf(stderr, "Fail to convert vplmn %02x%02x%02x to mcc/mnc for imsi %s\n",
            vplmn[0], vplmn[1], vplmn[2], imsi);
    return -1;
  }

  fprintf(stderr, "Converted %02x%02x%02x to plmn %u.%u\n", vplmn[0], vplmn[1], vplmn[2],
          FORMAT_MCC(vmcc), FORMAT_MNC(vmnc));

  /* MCC is always 3 digits */
  memcpy(hmcc, &imsi_hex[0], 3);

  if (memcmp(vmcc, hmcc, 3) != 0) {
    fprintf(stderr, "Only France MCC is handled for now, got imsi plmn %u.%u for a visited plmn %u.%u\n",
            FORMAT_MCC(hmcc), FORMAT_MNC(hmnc), FORMAT_MCC(vmcc), FORMAT_MNC(vmnc));
    /* Reject the association */
    return -1;
  }

  /* In France MNC is composed of 2 digits and thus imsi by 14 digit */
  hmnc[0] = 0;
  memcpy(&hmnc[1], &imsi_hex[3], 2);

  if ((memcmp(vmcc, hmcc, 3) != 0) && (memcmp(vmnc, hmnc, 3) != 0)) {
    fprintf(stderr, "UE is roaming from %u.%u to %u.%u which is not allowed"
            " by the ODB\n", FORMAT_MCC(hmcc), FORMAT_MNC(hmnc), FORMAT_MCC(vmcc), FORMAT_MNC(vmnc));
    return -1;
  }

  /* User has successfully passed all the checking -> accept the association */
  return 0;
}