/*
 * Copyright 2013-2020 Software Radio Systems Limited
 *
 * This file is part of srsLTE.
 *
 * srsLTE 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.
 *
 * srsLTE 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 Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#ifndef SRSUE_PCSC_USIM_H
#define SRSUE_PCSC_USIM_H

#include "srslte/common/common.h"
#include "srslte/common/log.h"
#include "srslte/common/security.h"
#include "srslte/interfaces/ue_interfaces.h"
#include "srsue/hdr/stack/upper/usim.h"
#include <string>
#include <winscard.h>

namespace srsue {

#define AKA_RAND_LEN 16
#define AKA_AUTN_LEN 16
#define AKA_AUTS_LEN 14
#define RES_MAX_LEN 16
#define MAC_LEN 8
#define IK_LEN 16
#define CK_LEN 16
#define AK_LEN 6
#define SQN_LEN 6

#define KEY_LEN 32

typedef enum { SCARD_GSM_SIM, SCARD_USIM } sim_types_t;

static inline uint16_t to_uint16(const uint8_t* a)
{
  return (a[0] << 8) | a[1];
}

class pcsc_usim : public usim_base
{
public:
  pcsc_usim(srslte::log* log_);
  ~pcsc_usim();
  int  init(usim_args_t* args);
  void stop();

  // NAS interface
  std::string get_imsi_str();
  std::string get_imei_str();

  bool get_imsi_vec(uint8_t* imsi_, uint32_t n);
  bool get_imei_vec(uint8_t* imei_, uint32_t n);
  bool get_home_plmn_id(srslte::plmn_id_t* home_plmn_id);

  auth_result_t generate_authentication_response(uint8_t* rand,
                                                 uint8_t* autn_enb,
                                                 uint16_t mcc,
                                                 uint16_t mnc,
                                                 uint8_t* res,
                                                 int*     res_len,
                                                 uint8_t* k_asme);

  void generate_nas_keys(uint8_t*                            k_asme,
                         uint8_t*                            k_nas_enc,
                         uint8_t*                            k_nas_int,
                         srslte::CIPHERING_ALGORITHM_ID_ENUM cipher_algo,
                         srslte::INTEGRITY_ALGORITHM_ID_ENUM integ_algo);

  // RRC interface
  void generate_as_keys(uint8_t* k_asme, uint32_t count_ul, srslte::as_security_config_t* sec_cfg);
  void generate_as_keys_ho(uint32_t pci, uint32_t earfcn, int ncc, srslte::as_security_config_t* sec_cfg);
  void store_keys_before_ho(const srslte::as_security_config_t& as_ctx);
  void restore_keys_from_failed_ho(srslte::as_security_config_t* as_ctx);

private:
  srslte::log* log = nullptr;

  // User data
  // 3GPP 33.102 v10.0.0 Annex H
  uint64_t imsi = 0;
  uint64_t imei = 0;

  std::string imsi_str;
  std::string imei_str;

  uint32_t mnc_length = 0;

  // Security variables
  uint8_t ck[CK_LEN]          = {};
  uint8_t ik[IK_LEN]          = {};
  uint8_t ak[AK_LEN]          = {};
  uint8_t k_asme[KEY_LEN]     = {};
  uint8_t nh[KEY_LEN]         = {};
  uint8_t k_enb[KEY_LEN]      = {};
  uint8_t k_enb_star[KEY_LEN] = {};
  uint8_t auts[AKA_AUTS_LEN]  = {};

  // Helpers to restore security context if HO fails
  uint8_t                      old_k_enb[32] = {};
  uint8_t                      old_ncc       = {};
  srslte::as_security_config_t old_as_ctx    = {};

  uint32_t current_ncc = 0;

  bool initiated = false;

  // Smartcard sub-class which is a port of the PC/SC smartcard implementation
  // of WPA Supplicant written by Jouni Malinen <j@w1.fi> and licensed under BSD
  // Source: https://w1.fi/cvs.html
  class scard
  {
  public:
    scard() : log(NULL){};
    ~scard(){};

    int  init(usim_args_t* args, srslte::log* log_);
    void deinit();

    int select_file(unsigned short file_id, unsigned char* buf, size_t* buf_len);
    int _select_file(unsigned short file_id,
                     unsigned char* buf,
                     size_t*        buf_len,
                     sim_types_t    sim_type,
                     unsigned char* aid,
                     size_t         aidlen);

    long transmit(unsigned char* _send, size_t send_len, unsigned char* _recv, size_t* recv_len);

    int get_aid(unsigned char* aid, size_t maxlen);
    int get_record_len(unsigned char recnum, unsigned char mode);
    int read_record(unsigned char* data, size_t len, unsigned char recnum, unsigned char mode);
    int get_imsi(char* imsi, size_t* len);
    int parse_fsp_templ(unsigned char* buf, size_t buf_len, int* ps_do, int* file_len);
    int read_file(unsigned char* data, size_t len);
    int get_mnc_len();
    int umts_auth(const unsigned char* _rand,
                  const unsigned char* autn,
                  unsigned char*       res,
                  int*                 res_len,
                  unsigned char*       ik,
                  unsigned char*       ck,
                  unsigned char*       auts);
    int pin_needed(unsigned char* hdr, size_t hlen);
    int verify_pin(const char* pin);
    int get_pin_retry_counter();

  private:
/* See ETSI GSM 11.11 and ETSI TS 102 221 for details.
 * SIM commands:
 * Command APDU: CLA INS P1 P2 P3 Data
 *   CLA (class of instruction): A0 for GSM, 00 for USIM
 *   INS (instruction)
 *   P1 P2 P3 (parameters, P3 = length of Data)
 * Response APDU: Data SW1 SW2
 *   SW1 SW2 (Status words)
 * Commands (INS P1 P2 P3):
 *   SELECT: A4 00 00 02 <file_id, 2 bytes>
 *   GET RESPONSE: C0 00 00 <len>
 *   RUN GSM ALG: 88 00 00 00 <RAND len = 10>
 *   RUN UMTS ALG: 88 00 81 <len=0x22> data: 0x10 | RAND | 0x10 | AUTN
 *	P1 = ID of alg in card
 *	P2 = ID of secret key
 *   READ BINARY: B0 <offset high> <offset low> <len>
 *   READ RECORD: B2 <record number> <mode> <len>
 *	P2 (mode) = '02' (next record), '03' (previous record),
 *		    '04' (absolute mode)
 *   VERIFY CHV: 20 00 <CHV number> 08
 *   CHANGE CHV: 24 00 <CHV number> 10
 *   DISABLE CHV: 26 00 01 08
 *   ENABLE CHV: 28 00 01 08
 *   UNBLOCK CHV: 2C 00 <00=CHV1, 02=CHV2> 10
 *   SLEEP: FA 00 00 00
 */

/* GSM SIM commands */
#define SIM_CMD_SELECT 0xa0, 0xa4, 0x00, 0x00, 0x02
#define SIM_CMD_RUN_GSM_ALG 0xa0, 0x88, 0x00, 0x00, 0x10
#define SIM_CMD_GET_RESPONSE 0xa0, 0xc0, 0x00, 0x00
#define SIM_CMD_READ_BIN 0xa0, 0xb0, 0x00, 0x00
#define SIM_CMD_READ_RECORD 0xa0, 0xb2, 0x00, 0x00
#define SIM_CMD_VERIFY_CHV1 0xa0, 0x20, 0x00, 0x01, 0x08

/* USIM commands */
#define USIM_CLA 0x00
#define USIM_CMD_RUN_UMTS_ALG 0x00, 0x88, 0x00, 0x81, 0x22
#define USIM_CMD_GET_RESPONSE 0x00, 0xc0, 0x00, 0x00

#define SIM_RECORD_MODE_ABSOLUTE 0x04

#define USIM_FSP_TEMPL_TAG 0x62

#define USIM_TLV_FILE_DESC 0x82
#define USIM_TLV_FILE_ID 0x83
#define USIM_TLV_DF_NAME 0x84
#define USIM_TLV_PROPR_INFO 0xA5
#define USIM_TLV_LIFE_CYCLE_STATUS 0x8A
#define USIM_TLV_FILE_SIZE 0x80
#define USIM_TLV_TOTAL_FILE_SIZE 0x81
#define USIM_TLV_PIN_STATUS_TEMPLATE 0xC6
#define USIM_TLV_SHORT_FILE_ID 0x88
#define USIM_TLV_SECURITY_ATTR_8B 0x8B
#define USIM_TLV_SECURITY_ATTR_8C 0x8C
#define USIM_TLV_SECURITY_ATTR_AB 0xAB

#define USIM_PS_DO_TAG 0x90

/* GSM files
 * File type in first octet:
 * 3F = Master File
 * 7F = Dedicated File
 * 2F = Elementary File under the Master File
 * 6F = Elementary File under a Dedicated File
 */
#define SCARD_FILE_MF 0x3F00
#define SCARD_FILE_GSM_DF 0x7F20
#define SCARD_FILE_UMTS_DF 0x7F50
#define SCARD_FILE_GSM_EF_IMSI 0x6F07
#define SCARD_FILE_GSM_EF_AD 0x6FAD
#define SCARD_FILE_EF_DIR 0x2F00
#define SCARD_FILE_EF_ICCID 0x2FE2
#define SCARD_FILE_EF_CK 0x6FE1
#define SCARD_FILE_EF_IK 0x6FE2

#define SCARD_CHV1_OFFSET 13
#define SCARD_CHV1_FLAG 0x80

    SCARDCONTEXT  scard_context;
    SCARDHANDLE   scard_handle;
    long unsigned scard_protocol;
    sim_types_t   sim_type;
    bool          pin1_needed;
    srslte::log*  log;
  };

  scard sc;
};

} // namespace srsue

#endif // SRSUE_PCSC_USIM_H