/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

#include "curl_setup.h"

#include "parsedate.h"

#include "curlx/strparse.h"

/*

  A brief summary of the date string formats this parser groks:

  RFC 2616 3.3.1

  Sun, 06 Nov 1994 08:49:37 GMT  ; RFC 822, updated by RFC 1123

  Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036

  Sun Nov  6 08:49:37 1994       ; ANSI C's asctime() format

  we support dates without week day name:

  06 Nov 1994 08:49:37 GMT

  06-Nov-94 08:49:37 GMT

  Nov  6 08:49:37 1994

  without the time zone:

  06 Nov 1994 08:49:37

  06-Nov-94 08:49:37

  weird order:

  1994 Nov 6 08:49:37  (GNU date fails)

  GMT 08:49:37 06-Nov-94 Sunday

  94 6 Nov 08:49:37    (GNU date fails)

  time left out:

  1994 Nov 6

  06-Nov-94

  Sun Nov 6 94

  unusual separators:

  1994.Nov.6

  Sun/Nov/6/94/GMT

  commonly used time zone names:

  Sun, 06 Nov 1994 08:49:37 CET

  06 Nov 1994 08:49:37 EST

  time zones specified using RFC822 style:

  Sun, 12 Sep 2004 15:05:58 -0700

  Sat, 11 Sep 2004 21:32:11 +0200

  compact numerical date strings:

  20040912 15:05:58 -0700

  20040911 +0200

*/

#define PARSEDATE_OK     0

#define PARSEDATE_FAIL   -1

#define PARSEDATE_LATER  1

#if defined(HAVE_TIME_T_UNSIGNED) || (SIZEOF_TIME_T < 5)

#define PARSEDATE_SOONER 2

#endif

#if !defined(CURL_DISABLE_PARSEDATE) || !defined(CURL_DISABLE_FTP) || \

  !defined(CURL_DISABLE_FILE) || defined(USE_GNUTLS)

/* These names are also used by FTP and FILE code */

const char * const Curl_wkday[] = {

  "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"

};

const char * const Curl_month[] = {

  "Jan", "Feb", "Mar", "Apr", "May", "Jun",

  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"

};

#endif

#ifndef CURL_DISABLE_PARSEDATE

static const char * const weekday[] = {

  "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"

};

struct tzinfo {

  char name[5];

  int offset; /* +/- in minutes */

};

/* Here's a bunch of frequently used time zone names. These were supported

   by the old getdate parser. */

#define tDAYZONE -60       /* offset for daylight savings time */

static const struct tzinfo tz[] = {

  { "GMT",     0 },          /* Greenwich Mean */

  { "UT",      0 },          /* Universal Time */

  { "UTC",     0 },          /* Universal (Coordinated) */

  { "WET",     0 },          /* Western European */

  { "BST",     0 tDAYZONE }, /* British Summer */

  { "WAT",    60 },          /* West Africa */

  { "AST",   240 },          /* Atlantic Standard */

  { "ADT",   240 tDAYZONE }, /* Atlantic Daylight */

  { "EST",   300 },          /* Eastern Standard */

  { "EDT",   300 tDAYZONE }, /* Eastern Daylight */

  { "CST",   360 },          /* Central Standard */

  { "CDT",   360 tDAYZONE }, /* Central Daylight */

  { "MST",   420 },          /* Mountain Standard */

  { "MDT",   420 tDAYZONE }, /* Mountain Daylight */

  { "PST",   480 },          /* Pacific Standard */

  { "PDT",   480 tDAYZONE }, /* Pacific Daylight */

  { "YST",   540 },          /* Yukon Standard */

  { "YDT",   540 tDAYZONE }, /* Yukon Daylight */

  { "HST",   600 },          /* Hawaii Standard */

  { "HDT",   600 tDAYZONE }, /* Hawaii Daylight */

  { "CAT",   600 },          /* Central Alaska */

  { "AHST",  600 },          /* Alaska-Hawaii Standard */

  { "NT",    660 },          /* Nome */ /* spellchecker:disable-line */

  { "IDLW",  720 },          /* International Date Line West */

  { "CET",   -60 },          /* Central European */

  { "MET",   -60 },          /* Middle European */

  { "MEWT",  -60 },          /* Middle European Winter */

  { "MEST",  -60 tDAYZONE }, /* Middle European Summer */

  { "CEST",  -60 tDAYZONE }, /* Central European Summer */

  { "MESZ",  -60 tDAYZONE }, /* Middle European Summer */

  { "FWT",   -60 },          /* French Winter */

  { "FST",   -60 tDAYZONE }, /* French Summer */

  { "EET",  -120 },          /* Eastern Europe, USSR Zone 1 */

  { "WAST", -420 }, /* spellchecker:disable-line */

                             /* West Australian Standard */

  { "WADT", -420 tDAYZONE }, /* West Australian Daylight */

  { "CCT",  -480 },          /* China Coast, USSR Zone 7 */

  { "JST",  -540 },          /* Japan Standard, USSR Zone 8 */

  { "EAST", -600 },          /* Eastern Australian Standard */

  { "EADT", -600 tDAYZONE }, /* Eastern Australian Daylight */

  { "GST",  -600 },          /* Guam Standard, USSR Zone 9 */

  { "NZT",  -720 },          /* New Zealand */

  { "NZST", -720 },          /* New Zealand Standard */

  { "NZDT", -720 tDAYZONE }, /* New Zealand Daylight */

  { "IDLE", -720 },          /* International Date Line East */

  /* Next up: Military timezone names. RFC822 allowed these, but (as noted in

     RFC 1123) had their signs wrong. Here we use the correct signs to match

     actual military usage.

   */

  { "A",   1 * 60 },         /* Alpha */

  { "B",   2 * 60 },         /* Bravo */

  { "C",   3 * 60 },         /* Charlie */

  { "D",   4 * 60 },         /* Delta */

  { "E",   5 * 60 },         /* Echo */

  { "F",   6 * 60 },         /* Foxtrot */

  { "G",   7 * 60 },         /* Golf */

  { "H",   8 * 60 },         /* Hotel */

  { "I",   9 * 60 },         /* India */

  /* "J", Juliet is not used as a timezone, to indicate the observer's local

     time */

  { "K",  10 * 60 },         /* Kilo */

  { "L",  11 * 60 },         /* Lima */

  { "M",  12 * 60 },         /* Mike */

  { "N",  -1 * 60 },         /* November */

  { "O",  -2 * 60 },         /* Oscar */

  { "P",  -3 * 60 },         /* Papa */

  { "Q",  -4 * 60 },         /* Quebec */

  { "R",  -5 * 60 },         /* Romeo */

  { "S",  -6 * 60 },         /* Sierra */

  { "T",  -7 * 60 },         /* Tango */

  { "U",  -8 * 60 },         /* Uniform */

  { "V",  -9 * 60 },         /* Victor */

  { "W", -10 * 60 },         /* Whiskey */

  { "X", -11 * 60 },         /* X-ray */

  { "Y", -12 * 60 },         /* Yankee */

  { "Z", 0 },                /* Zulu, zero meridian, a.k.a. UTC */

};

/* returns:

   -1 no day

   0 monday - 6 sunday

*/

static int checkday(const char *check, size_t len)

{

  int i;

  const char * const *what;

  if(len > 3)

    what = &weekday[0];

  else if(len == 3)

    what = &Curl_wkday[0];

  else

    return -1; /* too short */

  for(i = 0; i < 7; i++) {

    size_t ilen = strlen(what[0]);

    if((ilen == len) &&

       curl_strnequal(check, what[0], len))

      return i;

    what++;

  }

  return -1;

}

static int checkmonth(const char *check, size_t len)

{

  int i;

  const char * const *what = &Curl_month[0];

  if(len != 3)

    return -1; /* not a month */

  for(i = 0; i < 12; i++) {

    if(curl_strnequal(check, what[0], 3))

      return i;

    what++;

  }

  return -1; /* return the offset or -1, no real offset is -1 */

}

/* return the time zone offset between GMT and the input one, in number

   of seconds or -1 if the timezone was not found/legal */

static int checktz(const char *check, size_t len)

{

  unsigned int i;

  const struct tzinfo *what = tz;

  if(len > 4) /* longer than any valid timezone */

    return -1;

  for(i = 0; i < CURL_ARRAYSIZE(tz); i++) {

    size_t ilen = strlen(what->name);

    if((ilen == len) &&

       curl_strnequal(check, what->name, len))

      return what->offset * 60;

    what++;

  }

  return -1;

}

static void skip(const char **date)

{

  /* skip everything that are not letters or digits */

  while(**date && !ISALNUM(**date))

    (*date)++;

}

enum assume {

  DATE_MDAY,

  DATE_YEAR,

  DATE_TIME

};

/*

 * time2epoch: time stamp to seconds since epoch in GMT time zone. Similar to

 * mktime but for GMT only.

 */

static time_t time2epoch(int sec, int min, int hour,

                         int mday, int mon, int year)

{

  static const int month_days_cumulative[12] = {

    0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334

  };

  int leap_days = year - (mon <= 1);

  leap_days = ((leap_days / 4) - (leap_days / 100) + (leap_days / 400)

               - (1969 / 4) + (1969 / 100) - (1969 / 400));

  return ((((time_t)(year - 1970) * 365

            + leap_days + month_days_cumulative[mon] + mday - 1) * 24

           + hour) * 60 + min) * 60 + sec;

}

/* Returns the value of a single-digit or two-digit decimal number, return

   then pointer to after the number. The 'date' pointer is known to point to a

   digit. */

static int oneortwodigit(const char *date, const char **endp)

{

  int num = date[0] - '0';

  if(ISDIGIT(date[1])) {

    *endp = &date[2];

    return num * 10 + (date[1] - '0');

  }

  *endp = &date[1];

  return num;

}

/* HH:MM:SS or HH:MM and accept single-digits too */

static bool match_time(const char *date,

                       int *h, int *m, int *s, char **endp)

{

  const char *p;

  int hh, mm, ss = 0;

  hh = oneortwodigit(date, &p);

  if((hh < 24) && (*p == ':') && ISDIGIT(p[1])) {

    mm = oneortwodigit(&p[1], &p);

    if(mm < 60) {

      if((*p == ':') && ISDIGIT(p[1])) {

        ss = oneortwodigit(&p[1], &p);

        if(ss <= 60) {

          /* valid HH:MM:SS */

          goto match;

        }

      }

      else {

        /* valid HH:MM */

        goto match;

      }

    }

  }

  return FALSE; /* not a time string */

match:

  *h = hh;

  *m = mm;

  *s = ss;

  *endp = (char *)CURL_UNCONST(p);

  return TRUE;

}

/*

 * parsedate()

 *

 * Returns:

 *

 * PARSEDATE_OK     - a fine conversion

 * PARSEDATE_FAIL   - failed to convert

 * PARSEDATE_LATER  - time overflow at the far end of time_t

 * PARSEDATE_SOONER - time underflow at the low end of time_t

 */

/* Wednesday is the longest name this parser knows about */

#define NAME_LEN 12

static int parsedate(const char *date, time_t *output)

{

  time_t t = 0;

  int wdaynum = -1;  /* day of the week number, 0-6 (mon-sun) */

  int monnum = -1;   /* month of the year number, 0-11 */

  int mdaynum = -1;  /* day of month, 1 - 31 */

  int hournum = -1;

  int minnum = -1;

  int secnum = -1;

  int yearnum = -1;

  int tzoff = -1;

  enum assume dignext = DATE_MDAY;

  const char *indate = date; /* save the original pointer */

  int part = 0; /* max 6 parts */

  while(*date && (part < 6)) {

    bool found = FALSE;

    skip(&date);

    if(ISALPHA(*date)) {

      /* a name coming up */

      size_t len = 0;

      const char *p = date;

      while(ISALPHA(*p) && (len < NAME_LEN)) {

        p++;

        len++;

      }

      if(len != NAME_LEN) {

        if(wdaynum == -1) {

          wdaynum = checkday(date, len);

          if(wdaynum != -1)

            found = TRUE;

        }

        if(!found && (monnum == -1)) {

          monnum = checkmonth(date, len);

          if(monnum != -1)

            found = TRUE;

        }

        if(!found && (tzoff == -1)) {

          /* this just must be a time zone string */

          tzoff = checktz(date, len);

          if(tzoff != -1)

            found = TRUE;

        }

      }

      if(!found)

        return PARSEDATE_FAIL; /* bad string */

      date += len;

    }

    else if(ISDIGIT(*date)) {

      /* a digit */

      unsigned int val;

      char *end;

      if((secnum == -1) &&

         match_time(date, &hournum, &minnum, &secnum, &end)) {

        /* time stamp */

        date = end;

      }

      else {

        curl_off_t lval;

        int num_digits = 0;

        const char *p = date;

        if(curlx_str_number(&p, &lval, 99999999))

          return PARSEDATE_FAIL;

        /* we know num_digits cannot be larger than 8 */

        num_digits = (int)(p - date);

        val = (unsigned int)lval;

        if((tzoff == -1) &&

           (num_digits == 4) &&

           (val <= 1400) &&

           (indate < date) &&

           ((date[-1] == '+' || date[-1] == '-'))) {

          /* four digits and a value less than or equal to 1400 (to take into

             account all sorts of funny time zone diffs) and it is preceded

             with a plus or minus. This is a time zone indication. 1400 is

             picked since +1300 is frequently used and +1400 is mentioned as

             an edge number in the document "ISO C 200X Proposal: Timezone

             Functions" at http://david.tribble.com/text/c0xtimezone.html If

             anyone has a more authoritative source for the exact maximum time

             zone offsets, please speak up! */

          found = TRUE;

          tzoff = (val / 100 * 60 + val % 100) * 60;

          /* the + and - prefix indicates the local time compared to GMT,

             this we need their reversed math to get what we want */

          tzoff = date[-1] == '+' ? -tzoff : tzoff;

        }

        else if((num_digits == 8) &&

                (yearnum == -1) &&

                (monnum == -1) &&

                (mdaynum == -1)) {

          /* 8 digits, no year, month or day yet. This is YYYYMMDD */

          found = TRUE;

          yearnum = val / 10000;

          monnum = (val % 10000) / 100 - 1; /* month is 0 - 11 */

          mdaynum = val % 100;

        }

        if(!found && (dignext == DATE_MDAY) && (mdaynum == -1)) {

          if((val > 0) && (val < 32)) {

            mdaynum = val;

            found = TRUE;

          }

          dignext = DATE_YEAR;

        }

        if(!found && (dignext == DATE_YEAR) && (yearnum == -1)) {

          yearnum = val;

          found = TRUE;

          if(yearnum < 100) {

            if(yearnum > 70)

              yearnum += 1900;

            else

              yearnum += 2000;

          }

          if(mdaynum == -1)

            dignext = DATE_MDAY;

        }

        if(!found)

          return PARSEDATE_FAIL;

        date = p;

      }

    }

    part++;

  }

  if(-1 == secnum)

    secnum = minnum = hournum = 0; /* no time, make it zero */

  if((-1 == mdaynum) ||

     (-1 == monnum) ||

     (-1 == yearnum))

    /* lacks vital info, fail */

    return PARSEDATE_FAIL;

#ifdef HAVE_TIME_T_UNSIGNED

  if(yearnum < 1970) {

    /* only positive numbers cannot return earlier */

    *output = TIME_T_MIN;

    return PARSEDATE_SOONER;

  }

#endif

#if (SIZEOF_TIME_T < 5)

#ifdef HAVE_TIME_T_UNSIGNED

  /* an unsigned 32-bit time_t can only hold dates to 2106 */

  if(yearnum > 2105) {

    *output = TIME_T_MAX;

    return PARSEDATE_LATER;

  }

#else

  /* a signed 32-bit time_t can only hold dates to the beginning of 2038 */

  if(yearnum > 2037) {

    *output = TIME_T_MAX;

    return PARSEDATE_LATER;

  }

  if(yearnum < 1903) {

    *output = TIME_T_MIN;

    return PARSEDATE_SOONER;

  }

#endif

#else

  /* The Gregorian calendar was introduced 1582 */

  if(yearnum < 1583)

    return PARSEDATE_FAIL;

#endif

  if((mdaynum > 31) || (monnum > 11) ||

     (hournum > 23) || (minnum > 59) || (secnum > 60))

    return PARSEDATE_FAIL; /* clearly an illegal date */

  /* time2epoch() returns a time_t. time_t is often 32 bits, sometimes even on

     architectures that feature a 64 bits 'long' but ultimately time_t is the

     correct data type to use.

  */

  t = time2epoch(secnum, minnum, hournum, mdaynum, monnum, yearnum);

  /* Add the time zone diff between local time zone and GMT. */

  if(tzoff == -1)

    tzoff = 0;

  if((tzoff > 0) && (t > (time_t)(TIME_T_MAX - tzoff))) {

    *output = TIME_T_MAX;

    return PARSEDATE_LATER; /* time_t overflow */

  }

  t += tzoff;

  *output = t;

  return PARSEDATE_OK;

}

#else

/* disabled */

static int parsedate(const char *date, time_t *output)

{

  (void)date;

  *output = 0;

  return PARSEDATE_OK; /* a lie */

}

#endif

time_t curl_getdate(const char *p, const time_t *now)

{

  time_t parsed = -1;

  int rc = parsedate(p, &parsed);

  (void)now; /* legacy argument from the past that we ignore */

  if(rc == PARSEDATE_OK) {

    if(parsed == (time_t)-1)

      /* avoid returning -1 for a working scenario */

      parsed++;

    return parsed;

  }

  /* everything else is fail */

  return -1;

}

/* Curl_getdate_capped() differs from curl_getdate() in that this will return

   TIME_T_MAX in case the parsed time value was too big, instead of an

   error. Returns non-zero on error. */

int Curl_getdate_capped(const char *p, time_t *tp)

{

  int rc = parsedate(p, tp);

  return (rc == PARSEDATE_FAIL);

}