/*

 * Copyright (C) 2003-2016 Free Software Foundation, Inc.

 * Copyright (C) 2016 Red Hat, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include <libtasn1.h>

#include "datum.h"

#include "global.h"

#include "errors.h"

#include "str.h"

#include "x509.h"

#include "num.h"

#include "x509_b64.h"

#include "x509_int.h"

#include "extras/hex.h"

#include "common.h"

#include <c-ctype.h>

/* TIME functions

 * Conversions between generalized or UTC time to time_t

 *

 */

/* This is an emulation of the struct tm.

 * Since we do not use libc's functions, we don't need to

 * depend on the libc structure.

 */

typedef struct fake_tm {

  int tm_mon;

  int tm_year; /* FULL year - ie 1971 */

  int tm_mday;

  int tm_hour;

  int tm_min;

  int tm_sec;

} fake_tm;

/* The mktime_utc function is due to Russ Allbery (rra@stanford.edu),

 * who placed it under public domain:

 */

/* The number of days in each month.

 */

static const int MONTHDAYS[] = {

  31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31

};

/* Whether a given year is a leap year. */

#define ISLEAP(year) \

  (((year) % 4) == 0 && (((year) % 100) != 0 || ((year) % 400) == 0))

/*

 **  Given a struct tm representing a calendar time in UTC, convert it to

 **  seconds since epoch.  Returns (time_t) -1 if the time is not

 **  convertible.  Note that this function does not canonicalize the provided

 **  struct tm, nor does it allow out of range values or years before 1970.

 */

static time_t mktime_utc(const struct fake_tm *tm)

{

  time_t result = 0;

  int i;

  /* We do allow some ill-formed dates, but we don't do anything special

 * with them and our callers really shouldn't pass them to us.  Do

 * explicitly disallow the ones that would cause invalid array accesses

 * or other algorithm problems.

 */

  if (tm->tm_mon < 0 || tm->tm_mon > 11 || tm->tm_year < 1970)

    return (time_t)-1;

  /* Check for "obvious" mistakes in dates */

  if (tm->tm_sec > 60 || tm->tm_min > 59 || tm->tm_mday > 31 ||

      tm->tm_mday < 1 || tm->tm_hour > 23)

    return (time_t)-1;

  /* Convert to a time_t.

 */

  for (i = 1970; i < tm->tm_year; i++)

    result += 365 + ISLEAP(i);

  for (i = 0; i < tm->tm_mon; i++)

    result += MONTHDAYS[i];

  if (tm->tm_mon > 1 && ISLEAP(tm->tm_year))

    result++;

  result = 24 * (result + tm->tm_mday - 1) + tm->tm_hour;

  result = 60 * result + tm->tm_min;

  result = 60 * result + tm->tm_sec;

  return result;

}

/* this one will parse dates of the form:

 * month|day|hour|minute|sec* (2 chars each)

 * and year is given. Returns a time_t date.

 */

static time_t time2gtime(const char *ttime, int year)

{

  char xx[4];

  struct fake_tm etime;

  if (strlen(ttime) < 8) {

    gnutls_assert();

    return (time_t)-1;

  }

  etime.tm_year = year;

  /* In order to work with 32 bit

   * time_t.

   */

  if (sizeof(time_t) <= 4 && etime.tm_year >= 2038)

    return (time_t)2145914603; /* 2037-12-31 23:23:23 */

  if (etime.tm_year < 1970)

    return (time_t)0;

  xx[2] = 0;

  /* get the month

 */

  memcpy(xx, ttime, 2); /* month */

  etime.tm_mon = atoi(xx) - 1;

  ttime += 2;

  /* get the day

 */

  memcpy(xx, ttime, 2); /* day */

  etime.tm_mday = atoi(xx);

  ttime += 2;

  /* get the hour

 */

  memcpy(xx, ttime, 2); /* hour */

  etime.tm_hour = atoi(xx);

  ttime += 2;

  /* get the minutes

 */

  memcpy(xx, ttime, 2); /* minutes */

  etime.tm_min = atoi(xx);

  ttime += 2;

  if (strlen(ttime) >= 2) {

    memcpy(xx, ttime, 2);

    etime.tm_sec = atoi(xx);

  } else

    etime.tm_sec = 0;

  return mktime_utc(&etime);

}

/* returns a time_t value that contains the given time.

 * The given time is expressed as:

 * YEAR(2)|MONTH(2)|DAY(2)|HOUR(2)|MIN(2)|SEC(2)*

 *

 * (seconds are optional)

 */

time_t _gnutls_utcTime2gtime(const char *ttime)

{

  char xx[3];

  int year, i;

  int len = strlen(ttime);

  if (len < 10) {

    gnutls_assert();

    return (time_t)-1;

  }

#ifdef STRICT_DER_TIME

  /* Make sure everything else is digits. */

  for (i = 0; i < len - 1; i++) {

    if (c_isdigit(ttime[i]))

      continue;

    return gnutls_assert_val((time_t)-1);

  }

#endif

  xx[2] = 0;

  /* get the year

 */

  memcpy(xx, ttime, 2); /* year */

  year = atoi(xx);

  ttime += 2;

  if (year > 49)

    year += 1900;

  else

    year += 2000;

  return time2gtime(ttime, year);

}

/* returns a time_t value that contains the given time.

 * The given time is expressed as:

 * YEAR(4)|MONTH(2)|DAY(2)|HOUR(2)|MIN(2)|SEC(2)*

 */

time_t _gnutls_x509_generalTime2gtime(const char *ttime)

{

  char xx[5];

  int year;

  if (strlen(ttime) < 12) {

    gnutls_assert();

    return (time_t)-1;

  }

  if (strchr(ttime, 'Z') == 0) {

    gnutls_assert();

    /* required to be in GMT */

    return (time_t)-1;

  }

  if (strchr(ttime, '.') != 0) {

    gnutls_assert();

    /* no fractional seconds allowed */

    return (time_t)-1;

  }

  xx[4] = 0;

  /* get the year

 */

  memcpy(xx, ttime, 4); /* year */

  year = atoi(xx);

  ttime += 4;

  return time2gtime(ttime, year);

}

#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Wformat-y2k"

/* tag will contain ASN1_TAG_UTCTime or ASN1_TAG_GENERALIZEDTime */

static int gtime_to_suitable_time(time_t gtime, char *str_time,

          size_t str_time_size, unsigned *tag)

{

  size_t ret;

  struct tm _tm;

  if (gtime == (time_t)-1

#if SIZEOF_LONG == 8

      || gtime >= 253402210800

#endif

  ) {

    if (tag)

      *tag = ASN1_TAG_GENERALIZEDTime;

    snprintf(str_time, str_time_size, "99991231235959Z");

    return 0;

  }

  if (!gmtime_r(&gtime, &_tm)) {

    gnutls_assert();

    return GNUTLS_E_INTERNAL_ERROR;

  }

  if (_tm.tm_year >= 150) {

    if (tag)

      *tag = ASN1_TAG_GENERALIZEDTime;

    ret = strftime(str_time, str_time_size, "%Y%m%d%H%M%SZ", &_tm);

  } else {

    if (tag)

      *tag = ASN1_TAG_UTCTime;

    ret = strftime(str_time, str_time_size, "%y%m%d%H%M%SZ", &_tm);

  }

  if (!ret) {

    gnutls_assert();

    return GNUTLS_E_SHORT_MEMORY_BUFFER;

  }

  return 0;

}

#pragma GCC diagnostic pop

static int gtime_to_generalTime(time_t gtime, char *str_time,

        size_t str_time_size)

{

  size_t ret;

  struct tm _tm;

  if (gtime == (time_t)-1

#if SIZEOF_LONG == 8

      || gtime >= 253402210800

#endif

  ) {

    snprintf(str_time, str_time_size, "99991231235959Z");

    return 0;

  }

  if (!gmtime_r(&gtime, &_tm)) {

    gnutls_assert();

    return GNUTLS_E_INTERNAL_ERROR;

  }

  ret = strftime(str_time, str_time_size, "%Y%m%d%H%M%SZ", &_tm);

  if (!ret) {

    gnutls_assert();

    return GNUTLS_E_SHORT_MEMORY_BUFFER;

  }

  return 0;

}

/* Extracts the time in time_t from the asn1_node given. When should

 * be something like "tbsCertList.thisUpdate".

 */

#define MAX_TIME 64

time_t _gnutls_x509_get_time(asn1_node c2, const char *where, int force_general)

{

  char ttime[MAX_TIME];

  char name[128];

  time_t c_time = (time_t)-1;

  int len, result;

  len = sizeof(ttime) - 1;

  result = asn1_read_value(c2, where, ttime, &len);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    return (time_t)(-1);

  }

  if (force_general != 0) {

    c_time = _gnutls_x509_generalTime2gtime(ttime);

  } else {

    _gnutls_str_cpy(name, sizeof(name), where);

    /* choice */

    if (strcmp(ttime, "generalTime") == 0) {

      if (name[0] == 0)

        _gnutls_str_cpy(name, sizeof(name),

            "generalTime");

      else

        _gnutls_str_cat(name, sizeof(name),

            ".generalTime");

      len = sizeof(ttime) - 1;

      result = asn1_read_value(c2, name, ttime, &len);

      if (result == ASN1_SUCCESS)

        c_time = _gnutls_x509_generalTime2gtime(ttime);

    } else { /* UTCTIME */

      if (name[0] == 0)

        _gnutls_str_cpy(name, sizeof(name), "utcTime");

      else

        _gnutls_str_cat(name, sizeof(name), ".utcTime");

      len = sizeof(ttime) - 1;

      result = asn1_read_value(c2, name, ttime, &len);

      if (result == ASN1_SUCCESS)

        c_time = _gnutls_utcTime2gtime(ttime);

    }

    /* We cannot handle dates after 2031 in 32 bit machines.

     * a time_t of 64bits has to be used.

     */

    if (result != ASN1_SUCCESS) {

      gnutls_assert();

      return (time_t)(-1);

    }

  }

  return c_time;

}

/* Sets the time in time_t in the asn1_node given. Where should

 * be something like "tbsCertList.thisUpdate".

 */

int _gnutls_x509_set_time(asn1_node c2, const char *where, time_t tim,

        int force_general)

{

  char str_time[MAX_TIME];

  char name[128];

  int result, len;

  unsigned tag;

  if (force_general != 0) {

    result = gtime_to_generalTime(tim, str_time, sizeof(str_time));

    if (result < 0)

      return gnutls_assert_val(result);

    len = strlen(str_time);

    result = asn1_write_value(c2, where, str_time, len);

    if (result != ASN1_SUCCESS)

      return gnutls_assert_val(_gnutls_asn2err(result));

    return 0;

  }

  result = gtime_to_suitable_time(tim, str_time, sizeof(str_time), &tag);

  if (result < 0) {

    gnutls_assert();

    return result;

  }

  _gnutls_str_cpy(name, sizeof(name), where);

  if (tag == ASN1_TAG_UTCTime) {

    if ((result = asn1_write_value(c2, where, "utcTime", 1)) !=

        ASN1_SUCCESS) {

      gnutls_assert();

      return _gnutls_asn2err(result);

    }

    _gnutls_str_cat(name, sizeof(name), ".utcTime");

  } else {

    if ((result = asn1_write_value(c2, where, "generalTime", 1)) !=

        ASN1_SUCCESS) {

      gnutls_assert();

      return _gnutls_asn2err(result);

    }

    _gnutls_str_cat(name, sizeof(name), ".generalTime");

  }

  len = strlen(str_time);

  result = asn1_write_value(c2, name, str_time, len);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  return 0;

}

/* This will set a DER encoded Time element. To be used in fields

 * which are of the ANY.

 */

int _gnutls_x509_set_raw_time(asn1_node c2, const char *where, time_t tim)

{

  char str_time[MAX_TIME];

  uint8_t buf[128];

  int result, len, der_len;

  unsigned tag;

  result = gtime_to_suitable_time(tim, str_time, sizeof(str_time), &tag);

  if (result < 0)

    return gnutls_assert_val(result);

  len = strlen(str_time);

  buf[0] = tag;

  asn1_length_der(len, buf + 1, &der_len);

  if ((unsigned)len > sizeof(buf) - der_len - 1) {

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  }

  memcpy(buf + 1 + der_len, str_time, len);

  result = asn1_write_value(c2, where, buf, len + 1 + der_len);

  if (result != ASN1_SUCCESS)

    return gnutls_assert_val(_gnutls_asn2err(result));

  return 0;

}