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

#include "mme_config.h"

#include "assertions.h"
#include "conversions.h"

#include "intertask_interface.h"
#include "security_types.h"
#include "s6a_defs.h"
#include "s6a_messages.h"
#include "msc.h"

static
int s6a_parse_rand(struct avp_hdr *hdr, uint8_t *rand_p)
{
  int ret = 0;
  DevCheck(hdr->avp_value->os.len == RAND_LENGTH_OCTETS, RAND_LENGTH_OCTETS,
           hdr->avp_value->os.len, 0);
  DevAssert(rand_p != NULL);

  STRING_TO_RAND(hdr->avp_value->os.data, rand_p, ret);
  return ret;
}

static
int s6a_parse_xres(struct avp_hdr *hdr, res_t *xres)
{
  int ret = 0;
  DevCheck(hdr->avp_value->os.len >= XRES_LENGTH_MIN &&
           hdr->avp_value->os.len <= XRES_LENGTH_MAX, XRES_LENGTH_MIN,
           XRES_LENGTH_MAX, hdr->avp_value->os.len);
  DevAssert(xres != NULL);

  STRING_TO_XRES(hdr->avp_value->os.data, hdr->avp_value->os.len, xres, ret);
  return ret;
}

static
int s6a_parse_autn(struct avp_hdr *hdr, uint8_t *autn)
{
  int ret = 0;
  DevCheck(hdr->avp_value->os.len == AUTN_LENGTH_OCTETS, AUTN_LENGTH_OCTETS,
           hdr->avp_value->os.len, 0);
  DevAssert(autn != NULL);

  STRING_TO_AUTN(hdr->avp_value->os.data, autn, ret);
  return ret;
}

static
int s6a_parse_kasme(struct avp_hdr *hdr, uint8_t *kasme)
{
  int ret = 0;
  DevCheck(hdr->avp_value->os.len == KASME_LENGTH_OCTETS, KASME_LENGTH_OCTETS,
           hdr->avp_value->os.len, 0);
  DevAssert(kasme != NULL);

  STRING_TO_KASME(hdr->avp_value->os.data, kasme, ret);
  return ret;
}

static inline
int s6a_parse_e_utran_vector(struct avp *avp_vector, eutran_vector_t *vector)
{
  int ret = 0x0f;
  struct avp *avp;
  struct avp_hdr *hdr;

  CHECK_FCT(fd_msg_avp_hdr(avp_vector, &hdr));

  DevCheck(hdr->avp_code == AVP_CODE_E_UTRAN_VECTOR,
           hdr->avp_code, AVP_CODE_E_UTRAN_VECTOR, 0);

  CHECK_FCT(fd_msg_browse(avp_vector, MSG_BRW_FIRST_CHILD, &avp, NULL));

  while(avp) {
    CHECK_FCT(fd_msg_avp_hdr(avp, &hdr));

    switch(hdr->avp_code) {
    case AVP_CODE_RAND:
      CHECK_FCT(s6a_parse_rand(hdr, vector->rand));
      ret &= ~0x01;
      break;

    case AVP_CODE_XRES:
      CHECK_FCT(s6a_parse_xres(hdr, &vector->xres));
      ret &= ~0x02;
      break;

    case AVP_CODE_AUTN:
      CHECK_FCT(s6a_parse_autn(hdr, vector->autn));
      ret &= ~0x04;
      break;

    case AVP_CODE_KASME:
      CHECK_FCT(s6a_parse_kasme(hdr, vector->kasme));
      ret &= ~0x08;
      break;

    default:
      /* Unexpected AVP */
      S6A_ERROR("Unexpected AVP with code %d\n", hdr->avp_code);
      return -1;
    }

    /* Go to next AVP in the grouped AVP */
    CHECK_FCT(fd_msg_browse(avp, MSG_BRW_NEXT, &avp, NULL));
  }

  if (ret) {
    S6A_ERROR("Missing AVP for E-UTRAN vector: %c%c%c%c\n",
              ret & 0x01 ? 'R':'-', ret & 0x02 ? 'X':'-',
              ret & 0x04 ? 'A':'-', ret & 0x08 ? 'K':'-');
    return -1;
  }

  return 0;
}

static inline
int s6a_parse_authentication_info_avp(struct avp *avp_auth_info,
                                      authentication_info_t *authentication_info)
{
  struct avp *avp;
  struct avp_hdr *hdr;

  CHECK_FCT(fd_msg_avp_hdr(avp_auth_info, &hdr));

  DevCheck(hdr->avp_code == AVP_CODE_AUTHENTICATION_INFO,
           hdr->avp_code, AVP_CODE_AUTHENTICATION_INFO, 0);

  authentication_info->nb_of_vectors = 0;

  CHECK_FCT(fd_msg_browse(avp_auth_info, MSG_BRW_FIRST_CHILD, &avp, NULL));

  while(avp) {
    CHECK_FCT(fd_msg_avp_hdr(avp, &hdr));

    switch(hdr->avp_code) {
    case AVP_CODE_E_UTRAN_VECTOR: {
      DevAssert(authentication_info->nb_of_vectors == 0);
      CHECK_FCT(s6a_parse_e_utran_vector(avp, &authentication_info->eutran_vector));
      authentication_info->nb_of_vectors ++;
    }
    break;

    default:
      /* We should only receive E-UTRAN-Vectors */
      S6A_ERROR("Unexpected AVP with code %d\n", hdr->avp_code);
      return -1;
    }

    /* Go to next AVP in the grouped AVP */
    CHECK_FCT(fd_msg_browse(avp, MSG_BRW_NEXT, &avp, NULL));
  }

  return 0;
}

int s6a_aia_cb(struct msg **msg, struct avp *paramavp,
               struct session *sess, void *opaque,
               enum disp_action *act)
{
  struct msg           *ans                = NULL;
  struct msg           *qry                = NULL;
  struct avp           *avp                = NULL;
  struct avp_hdr       *hdr                = NULL;

  MessageDef          *message_p           = NULL;
  s6a_auth_info_ans_t *s6a_auth_info_ans_p = NULL;

  int skip_auth_res = 0;

  DevAssert(msg != NULL);

  ans = *msg;
  /* Retrieve the original query associated with the asnwer */
  CHECK_FCT(fd_msg_answ_getq(ans, &qry));

  DevAssert(qry != NULL);

  message_p = itti_alloc_new_message(TASK_S6A, S6A_AUTH_INFO_ANS);
  s6a_auth_info_ans_p = &message_p->ittiMsg.s6a_auth_info_ans;

  S6A_DEBUG("Received S6A Authentication Information Answer (AIA)\n");

  CHECK_FCT(fd_msg_search_avp(qry, s6a_fd_cnf.dataobj_s6a_user_name, &avp));

  if (avp) {
    CHECK_FCT(fd_msg_avp_hdr(avp, &hdr));
    sprintf(s6a_auth_info_ans_p->imsi, "%*s", (int)hdr->avp_value->os.len,
            hdr->avp_value->os.data);
  } else {
    DevMessage("Query has been freed before we received the answer\n");
  }

  /* Retrieve the result-code */
  CHECK_FCT(fd_msg_search_avp(ans, s6a_fd_cnf.dataobj_s6a_result_code, &avp));

  if (avp) {
    CHECK_FCT(fd_msg_avp_hdr(avp, &hdr));

    s6a_auth_info_ans_p->result.present = S6A_RESULT_BASE;
    s6a_auth_info_ans_p->result.choice.base = hdr->avp_value->u32;

    MSC_LOG_TX_MESSAGE(
  	    MSC_S6A_MME,
    	MSC_MMEAPP_MME,
    	NULL,0,
    	"0 S6A_AUTH_INFO_ANS imsi %s %s",
    	s6a_auth_info_ans_p->imsi,
    	retcode_2_string(s6a_auth_info_ans_p->result.choice.base));

    if (hdr->avp_value->u32 != ER_DIAMETER_SUCCESS) {
      S6A_ERROR("Got error %u:%s\n", hdr->avp_value->u32,
                retcode_2_string(hdr->avp_value->u32));
      goto err;
    } else {
      S6A_DEBUG("Received S6A Result code %u:%s\n",
                s6a_auth_info_ans_p->result.choice.base,
                retcode_2_string(s6a_auth_info_ans_p->result.choice.base));
    }
  } else {
    /* The result-code is not present, may be it is an experimental result
     * avp indicating a 3GPP specific failure.
     */
    CHECK_FCT(fd_msg_search_avp(ans, s6a_fd_cnf.dataobj_s6a_experimental_result, &avp));

    if (avp) {
      /* The procedure has failed within the HSS.
       * NOTE: contrary to result-code, the experimental-result is a grouped
       * AVP and requires parsing its childs to get the code back.
       */
      s6a_auth_info_ans_p->result.present = S6A_RESULT_EXPERIMENTAL;
      s6a_parse_experimental_result(avp, &s6a_auth_info_ans_p->result.choice.experimental);

      MSC_LOG_TX_MESSAGE(
    	    MSC_S6A_MME,
      	MSC_MMEAPP_MME,
      	NULL,0,
      	"0 S6A_AUTH_INFO_ANS imsi %s %s",
      	s6a_auth_info_ans_p->imsi,
      	experimental_retcode_2_string(s6a_auth_info_ans_p->result.choice.experimental));

      skip_auth_res = 1;
    } else {
      /* Neither result-code nor experimental-result is present ->
       * totally incorrect behaviour here.
       */
    	MSC_LOG_TX_MESSAGE_FAILED(
      	    MSC_S6A_MME,
        	MSC_MMEAPP_MME,
        	NULL,0,
        	"0 S6A_AUTH_INFO_ANS imsi %s",
        	s6a_auth_info_ans_p->imsi);

      S6A_ERROR("Experimental-Result and Result-Code are absent: "
                "This is not a correct behaviour\n");
      goto err;
    }
  }

  if (skip_auth_res == 0) {
    CHECK_FCT(fd_msg_search_avp(ans, s6a_fd_cnf.dataobj_s6a_authentication_info, &avp));

    if (avp) {
      CHECK_FCT(s6a_parse_authentication_info_avp(avp, &s6a_auth_info_ans_p->auth_info));
    } else {
      DevMessage("We requested E-UTRAN vectors with an immediate response...\n");
    }
  }
  itti_send_msg_to_task(TASK_MME_APP, INSTANCE_DEFAULT, message_p);
err:
  return 0;
}

int s6a_generate_authentication_info_req(s6a_auth_info_req_t *air_p)
{
  struct avp     *avp;
  struct msg     *msg;
  struct session *sess;

  union avp_value value;

  DevAssert(air_p != NULL);

  /* Create the new update location request message */
  CHECK_FCT(fd_msg_new(s6a_fd_cnf.dataobj_s6a_air, 0, &msg));

  /* Create a new session */
  CHECK_FCT(fd_sess_new(&sess, fd_g_config->cnf_diamid,
                        fd_g_config->cnf_diamid_len, (os0_t)"apps6a", 6));
  {
    os0_t sid;
    size_t sidlen;
    CHECK_FCT(fd_sess_getsid(sess, &sid, &sidlen));
    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_session_id, 0, &avp));
    value.os.data = sid;
    value.os.len  = sidlen;
    CHECK_FCT(fd_msg_avp_setvalue(avp, &value));
    CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_FIRST_CHILD, avp));
  }

  CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_auth_session_state, 0, &avp));
  /* No State maintained */
  value.i32 = 1;
  CHECK_FCT(fd_msg_avp_setvalue(avp, &value));
  CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));

  /* Add Origin_Host & Origin_Realm */
  CHECK_FCT(fd_msg_add_origin(msg, 0));

  config_read_lock(&mme_config);

  /* Destination Host */
  {
    char host[100];
    size_t hostlen;

    memset(host, 0, 100);
    strcat(host, mme_config.s6a_config.hss_host_name);
    strcat(host, ".");
    strcat(host, mme_config.realm);

    hostlen = strlen(host);

    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_destination_host, 0, &avp));
    value.os.data = (unsigned char *)host;
    value.os.len  = hostlen;
    CHECK_FCT(fd_msg_avp_setvalue(avp, &value));

    CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));
  }
  /* Destination_Realm */
  {
    char *realm     = mme_config.realm;
    size_t realmlen = strlen(realm);

    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_destination_realm, 0, &avp));
    value.os.data = (unsigned char *)realm;
    value.os.len  = realmlen;
    CHECK_FCT(fd_msg_avp_setvalue(avp, &value));

    CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));
  }

  config_unlock(&mme_config);

  /* Adding the User-Name (IMSI) */
  CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_user_name, 0, &avp));
  value.os.data = (unsigned char *)air_p->imsi;
  value.os.len  = strlen(air_p->imsi);
  CHECK_FCT(fd_msg_avp_setvalue(avp, &value));
  CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));

  /* Adding the visited plmn id */
  {
    uint8_t plmn[3] = { 0x00, 0x00, 0x00 }; //{ 0x02, 0xF8, 0x29 };

    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_visited_plmn_id, 0, &avp));


    PLMN_T_TO_TBCD(air_p->visited_plmn,
                   plmn,
                   mme_config_find_mnc_length(air_p->visited_plmn.MCCdigit1,
                       air_p->visited_plmn.MCCdigit2,
                       air_p->visited_plmn.MCCdigit3,
                       air_p->visited_plmn.MNCdigit1,
                       air_p->visited_plmn.MNCdigit2,
                       air_p->visited_plmn.MNCdigit3
                                             )
                  );
    value.os.data = plmn;
    value.os.len  = 3;
    CHECK_FCT(fd_msg_avp_setvalue(avp, &value));

    CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));
    S6A_DEBUG("%s plmn: %02X%02X%02X\n",
              __FUNCTION__,
              plmn[0],
              plmn[1],
              plmn[2]);
    S6A_DEBUG("%s visited_plmn: %02X%02X%02X\n",
              __FUNCTION__,
              value.os.data[0],
              value.os.data[1],
              value.os.data[2]);
  }
  /* Adding the requested E-UTRAN authentication info AVP */
  {
    struct avp *child_avp;
    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_req_eutran_auth_info, 0, &avp));

    /* Add the number of requested vectors */
    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_number_of_requested_vectors, 0, &child_avp));
    value.u32 = air_p->nb_of_vectors;
    CHECK_FCT(fd_msg_avp_setvalue(child_avp, &value));
    CHECK_FCT(fd_msg_avp_add(avp, MSG_BRW_LAST_CHILD, child_avp));

    /* We want to use the vectors immediately in HSS so we have to add
     * the Immediate-Response-Preferred AVP.
     * Value of this AVP is not significant.
     */
    CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_immediate_response_pref, 0, &child_avp));
    value.u32 = 0;
    CHECK_FCT(fd_msg_avp_setvalue(child_avp, &value));
    CHECK_FCT(fd_msg_avp_add(avp, MSG_BRW_LAST_CHILD, child_avp));

    /* Re-synchronization information containing the AUTS computed at USIM */
    if (air_p->re_synchronization) {
      CHECK_FCT(fd_msg_avp_new(s6a_fd_cnf.dataobj_s6a_re_synchronization_info, 0, &child_avp));
      value.os.len = AUTS_LENGTH;
      value.os.data = air_p->auts;
      CHECK_FCT(fd_msg_avp_setvalue(child_avp, &value));
      CHECK_FCT(fd_msg_avp_add(avp, MSG_BRW_LAST_CHILD, child_avp));
    }

    CHECK_FCT(fd_msg_avp_add(msg, MSG_BRW_LAST_CHILD, avp));
  }
  CHECK_FCT(fd_msg_send(&msg, NULL, NULL));

  return 0;
}