/*
 * Copyright (c) 1997 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <string.h>
#include <stdlib.h>
#include <errno.h>

      #include <stdio.h>
#include <time.h>
typedef struct heim_octet_string {
    size_t length;
    void *data;
} heim_octet_string;

static int
is_leap(unsigned y)
{
    y += 1900;
    return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
}

/*
 * This is a simplifed version of timegm(3) that doesn't accept out of
 * bound values that timegm(3) normally accepts but those are not
 * valid in asn1 encodings.
 */

time_t
_der_timegm (struct tm *tm)
{
  static const unsigned ndays[2][12] ={
    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
  time_t res = 0;
  unsigned i;

  if (tm->tm_year < 0)
      return -1;
  if (tm->tm_mon < 0 || tm->tm_mon > 11)
      return -1;
  if (tm->tm_mday < 1 || tm->tm_mday > ndays[is_leap(tm->tm_year)][tm->tm_mon])
      return -1;
  if (tm->tm_hour < 0 || tm->tm_hour > 23)
      return -1;
  if (tm->tm_min < 0 || tm->tm_min > 59)
      return -1;
  if (tm->tm_sec < 0 || tm->tm_sec > 59)
      return -1;

  for (i = 70; i < tm->tm_year; ++i)
    res += is_leap(i) ? 366 : 365;

  for (i = 0; i < tm->tm_mon; ++i)
    res += ndays[is_leap(tm->tm_year)][i];
  res += tm->tm_mday - 1;
  res *= 24;
  res += tm->tm_hour;
  res *= 60;
  res += tm->tm_min;
  res *= 60;
  res += tm->tm_sec;
  return res;
}

static int
generalizedtime2time (const char *s, time_t *t)
{
    struct tm tm;

    memset(&tm, 0, sizeof(tm));
    if (sscanf (s, "%04d%02d%02d%02d%02d%02dZ",
		&tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
		&tm.tm_min, &tm.tm_sec) != 6) {
	if (sscanf (s, "%02d%02d%02d%02d%02d%02dZ",
		    &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
		    &tm.tm_min, &tm.tm_sec) != 6)
		abort();
	if (tm.tm_year < 50)
	    tm.tm_year += 2000;
	else
	    tm.tm_year += 1900;
    }
    tm.tm_year -= 1900;
    tm.tm_mon -= 1;
    *t = _der_timegm (&tm);
    return 0;
}

int
_heim_time2generalizedtime (time_t t, heim_octet_string *s, int gtimep)
{
	time_t t2;
     struct tm *tm;
     const size_t len = gtimep ? 15 : 13;

     s->data = malloc(len + 1);
     if (s->data == NULL)
	 return ENOMEM;
     s->length = len;
     tm = gmtime (&t);
     if (gtimep)
	 snprintf (s->data, len + 1, "%04d%02d%02d%02d%02d%02dZ",
		   tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
		   tm->tm_hour, tm->tm_min, tm->tm_sec);
     else
	 snprintf (s->data, len + 1, "%02d%02d%02d%02d%02d%02dZ",
		   tm->tm_year % 100, tm->tm_mon + 1, tm->tm_mday,
		   tm->tm_hour, tm->tm_min, tm->tm_sec);

     if (generalizedtime2time(s->data, &t2) != 0) {
	     abort();
     }
     if (t != t2) {
	     abort();
     }
     return 0;
}

int main(int argc, const char *argv[])
{
	heim_octet_string s;
	int gmtimep = 1;
	time_t t = 1285810267;
	return _heim_time2generalizedtime(t, &s, gmtimep);
}