/*

 * SPDX-License-Identifier: ISC

 *

 * Copyright (c) 2017, 2021 Todd C. Miller <Todd.Miller@sudo.ws>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#ifdef HAVE_STDBOOL_H

# include <stdbool.h>

#else

# include <compat/stdbool.h>

#endif /* HAVE_STDBOOL_H */

#include <string.h>

#include <ctype.h>

#include <time.h>

#include <sudo_compat.h>

#include <sudoers_debug.h>

#include <parse.h>

/* Since timegm() is only used in one place we keep the macro local. */

#ifndef HAVE_TIMEGM

# define timegm(_t) sudo_timegm(_t)

#endif

/*

 * Parse a timestamp in Generalized Time format as per RFC4517.

 * E.g. yyyymmddHHMMSS.FZ or yyyymmddHHMMSS.F[+-]TZOFF

 * where minutes, seconds and fraction are optional.

 * Returns the time in Unix time format or -1 on error.

 */

time_t

parse_gentime(const char *timestr)

{

    char tcopy[sizeof("yyyymmddHHMMSS")];

    const char *cp;

    time_t result;

    struct tm tm;

    size_t len;

    int items, tzoff = 0;

    bool islocal = false;

    debug_decl(parse_gentime, SUDOERS_DEBUG_PARSER);

    /* Make a copy of the non-fractional time without zone for easy parsing. */

    len = strspn(timestr, "0123456789");

    if (len >= sizeof(tcopy) || len < sizeof("yyyymmddHH") -1 || (len & 1)) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

      "unable to parse general time string %s", timestr);

  debug_return_time_t(-1);

    }

    memcpy(tcopy, timestr, len);

    tcopy[len] = '\0';

    /* Parse general time, ignoring the timezone for now. */

    memset(&tm, 0, sizeof(tm));

    items = sscanf(tcopy, "%4d%2d%2d%2d%2d%2d", &tm.tm_year, &tm.tm_mon,

  &tm.tm_mday, &tm.tm_hour, &tm.tm_min, &tm.tm_sec);

    if (items == EOF || items < 4) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

      "only parsed %d items in general time string %s", items, timestr); 

  debug_return_time_t(-1);

    }

    /* Parse optional fractional hours/minute/second if present. */

    cp = timestr + len;

    if ((cp[0] == '.' || cp[0] == ',') && isdigit((unsigned char)cp[1])) {

  int frac = cp[1] - '0';

  switch (items) {

  case 4:

      /* convert fractional hour -> minutes */

      tm.tm_min += 60 / 10 * frac;

      break;

  case 5:

      /* convert fractional minute -> seconds */

      tm.tm_sec += 60 / 10 * frac;

      break;

  case 6:

      /* ignore fractional second */

      break;

  }

  cp += 2;  /* skip over radix and fraction */

    }

    /* Parse optional time zone. */

    switch (*cp) {

    case '-':

    case '+': {

  int hour = 0, min = 0;

  /* No DST */

  tm.tm_isdst = 0;

  /* time zone offset must be hh or hhmm */

  len = strspn(cp + 1, "0123456789");

  if (len != 2 && len != 4) {

      sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

    "unable to parse time zone offset in %s, bad tz offset",

    timestr);

      debug_return_time_t(-1);

  }

  /* parse time zone offset */

  items = sscanf(cp + 1, "%2d%2d", &hour, &min);

  if (items == EOF || items < 1) {

      sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

    "unable to parse time zone offset in %s, items %d",

    timestr, items);

      debug_return_time_t(-1);

  }

  if (*cp == '-')

      tzoff = -((hour * 60) + min) * 60;

  else

      tzoff = ((hour * 60) + min) * 60;

  cp += 1 + (items * 2);

  break;

    }

    case 'Z':

  /* GMT/UTC, no DST */

  tm.tm_isdst = 0;

  cp++;

  break;

    case '\0':

  /* no zone specified, use local time */

  tm.tm_isdst = -1;

  islocal = true;

  break;

    default:

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

      "unable to parse general time string %s", timestr);

  debug_return_time_t(-1);

    }

    if (*cp != '\0') {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,

      "trailing garbage in general time string %s", timestr);

  debug_return_time_t(-1);

    }

    /* Adjust from Generalized Time to struct tm */

    tm.tm_year -= 1900;

    tm.tm_mon--;

    if (islocal) {

  result = mktime(&tm);

    } else {

  result = timegm(&tm);

  if (result != -1) {

      /* Adjust time based on supplied GMT offset. */

      result -= tzoff;

  }

    }

    debug_return_time_t(result);

}