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curl/lib/parsedate.c
Daniel Stenberg 2e3607034d
parsedate: refactor 
- introduce 'struct when' to hold the parser result
- initwhen() initializes a 'struct when'
- datestring() parses strings
- datenum() parses numbers
- datecheck() does some final checks
- tzadjust() adds the time zone offset
- convert math to 64 bit, squeeze into time_t only in the last step,
  mktimet() does the time_t storing

Closes #21394
2026-04-21 14:22:07 +02:00

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/***************************************************************************
* _ _ ____ _
* 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"
#include "curlx/strcopy.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
*/
#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
#define PARSEDATE_OK 0
#define PARSEDATE_FAIL (-1)
#ifndef CURL_DISABLE_PARSEDATE
#define PARSEDATE_LATER 1
#define PARSEDATE_SOONER 2
static const char * const weekday[] = {
"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"
};
struct tzinfo {
char name[5];
int16_t offset; /* +/- in minutes */
};
#define tDAYZONE (-60) /* offset for daylight savings time */
/* alpha-sorted list of time zones */
static const struct tzinfo tz[] = {
{ "A", -1 * 60 }, /* Alpha */
{ "ADT", 240 + tDAYZONE }, /* Atlantic Daylight */
{ "AHST", 600 }, /* Alaska-Hawaii Standard */
{ "AST", 240 }, /* Atlantic Standard */
{ "B", -2 * 60 }, /* Bravo */
{ "BST", 0 + tDAYZONE }, /* British Summer */
{ "C", -3 * 60 }, /* Charlie */
{ "CAT", 600 }, /* Central Alaska */
{ "CCT", -480 }, /* China Coast, USSR Zone 7 */
{ "CDT", 360 + tDAYZONE }, /* Central Daylight */
{ "CEST", -60 + tDAYZONE }, /* Central European Summer */
{ "CET", -60 }, /* Central European */
{ "CST", 360 }, /* Central Standard */
{ "D", -4 * 60 }, /* Delta */
{ "E", -5 * 60 }, /* Echo */
{ "EADT", -600 + tDAYZONE }, /* Eastern Australian Daylight */
{ "EAST", -600 }, /* Eastern Australian Standard */
{ "EDT", 300 + tDAYZONE }, /* Eastern Daylight */
{ "EET", -120 }, /* Eastern Europe, USSR Zone 1 */
{ "EST", 300 }, /* Eastern Standard */
{ "F", -6 * 60 }, /* Foxtrot */
{ "FST", -60 + tDAYZONE }, /* French Summer */
{ "FWT", -60 }, /* French Winter */
{ "G", -7 * 60 }, /* Golf */
{ "GMT", 0 }, /* Greenwich Mean */
{ "GST", -600 }, /* Guam Standard, USSR Zone 9 */
{ "H", -8 * 60 }, /* Hotel */
{ "HDT", 600 + tDAYZONE }, /* Hawaii Daylight */
{ "HST", 600 }, /* Hawaii Standard */
{ "I", -9 * 60 }, /* India */
{ "IDLE", -720 }, /* International Date Line East */
{ "IDLW", 720 }, /* International Date Line West */
{ "JST", -540 }, /* Japan Standard, USSR Zone 8 */
{ "K", -10 * 60 }, /* Kilo */
{ "L", -11 * 60 }, /* Lima */
{ "M", -12 * 60 }, /* Mike */
{ "MDT", 420 + tDAYZONE }, /* Mountain Daylight */
{ "MEST", -60 + tDAYZONE }, /* Middle European Summer */
{ "MESZ", -60 + tDAYZONE }, /* Middle European Summer */
{ "MET", -60 }, /* Middle European */
{ "MEWT", -60 }, /* Middle European Winter */
{ "MST", 420 }, /* Mountain Standard */
{ "N", 60 }, /* November */
{ "NT", 660 }, /* Nome */ /* spellchecker:disable-line */
{ "NZDT", -720 + tDAYZONE }, /* New Zealand Daylight */
{ "NZST", -720 }, /* New Zealand Standard */
{ "NZT", -720 }, /* New Zealand */
{ "O", 2 * 60 }, /* Oscar */
{ "P", 3 * 60 }, /* Papa */
{ "PDT", 480 + tDAYZONE }, /* Pacific Daylight */
{ "PST", 480 }, /* Pacific Standard */
{ "Q", 4 * 60 }, /* Quebec */
{ "R", 5 * 60 }, /* Romeo */
{ "S", 6 * 60 }, /* Sierra */
{ "T", 7 * 60 }, /* Tango */
{ "U", 8 * 60 }, /* Uniform */
{ "UT", 0 }, /* Universal Time */
{ "UTC", 0 }, /* Universal (Coordinated) */
{ "V", 9 * 60 }, /* Victor */
{ "W", 10 * 60 }, /* Whiskey */
{ "WADT", -420 + tDAYZONE }, /* West Australian Daylight */
{ "WAST", -420 }, /* spellchecker:disable-line */
/* West Australian Standard */
{ "WAT", 60 }, /* West Africa */
{ "WET", 0 }, /* Western European */
{ "X", 11 * 60 }, /* X-ray */
{ "Y", 12 * 60 }, /* Yankee */
{ "YDT", 540 + tDAYZONE }, /* Yukon Daylight */
{ "YST", 540 }, /* Yukon Standard */
{ "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 */
}
static int tzcompare(const void *m1, const void *m2)
{
const struct tzinfo *tz1 = m1;
const struct tzinfo *tz2 = m2;
return strcmp(tz1->name, tz2->name);
}
/* 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)
{
if(len <= 4) {
const struct tzinfo *what;
struct tzinfo find;
curlx_strcopy(find.name, sizeof(find.name), check, len);
what = bsearch(&find, tz, CURL_ARRAYSIZE(tz), sizeof(tz[0]), tzcompare);
if(what)
return what->offset * 60;
}
return -1;
}
static void skip(const char **date)
{
/* skip everything that are not letters or digits */
while(**date && !ISALNUM(**date))
(*date)++;
}
/* each field is exactly -1 when unknown */
struct when {
int wday; /* day of the week, 0-6 (mon-sun) */
int mon; /* month of the year, 0-11 */
int mday; /* day of month, 1 - 31 */
int hour; /* hour of day, 0 - 23 */
int min; /* minute of hour, 0 - 59 */
int sec; /* second of minute, 0 - 60 (leap second) */
int year; /* year, >= 1583 */
int tzoff; /* time zone offset in seconds */
};
enum assume {
DATE_MDAY,
DATE_YEAR,
DATE_TIME
};
/* (1969 / 4) - (1969 / 100) + (1969 / 400) = 492 - 19 + 4 = 477 */
#define LEAP_DAYS_BEFORE_1969 477
/*
* time2epoch: time stamp to seconds since epoch in GMT time zone. Similar to
* mktime but for GMT only.
*/
static curl_off_t time2epoch(struct when *w)
{
static const int cumulative_days[12] = {
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};
int y = w->year - (w->mon <= 1);
int leap_days = (y / 4) - (y / 100) + (y / 400) - LEAP_DAYS_BEFORE_1969;
curl_off_t days = (curl_off_t)(w->year - 1970) * 365 + leap_days +
cumulative_days[w->mon] + w->mday - 1;
return (((days * 24 + w->hour) * 60 + w->min) * 60) + w->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, struct when *w, 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:
w->hour = hh;
w->min = mm;
w->sec = 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 void initwhen(struct when *w)
{
w->wday = w->mon = w->mday = w->hour = w->min = w->sec = w->year = w->tzoff =
-1;
}
static int datestring(const char **datep, struct when *w)
{
/* a name coming up */
size_t len = 0;
const char *p = *datep;
bool found = FALSE;
while(ISALPHA(*p) && (len < NAME_LEN)) {
p++;
len++;
}
if(len != NAME_LEN) {
if(w->wday == -1) {
w->wday = checkday(*datep, len);
if(w->wday != -1)
found = TRUE;
}
if(!found && (w->mon == -1)) {
w->mon = checkmonth(*datep, len);
if(w->mon != -1)
found = TRUE;
}
if(!found && (w->tzoff == -1)) {
/* this must be a time zone string */
w->tzoff = checktz(*datep, len);
if(w->tzoff != -1)
found = TRUE;
}
}
if(!found)
return PARSEDATE_FAIL; /* bad string */
*datep += len;
return PARSEDATE_OK;
}
static int datenum(const char *indate, const char **datep, struct when *w,
enum assume *dignextp)
{
/* a digit */
unsigned int val;
char *end;
const char *date = *datep;
enum assume dignext = *dignextp;
if((w->sec == -1) && match_time(date, w, &end)) {
/* time stamp */
date = end;
}
else {
bool found = FALSE;
curl_off_t lval;
int num_digits = 0;
const char *p = *datep;
if(curlx_str_number(&p, &lval, 99999999))
return PARSEDATE_FAIL;
/* we know num_digits cannot be larger than 8 */
num_digits = (int)(p - *datep);
val = (unsigned int)lval;
if((w->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;
w->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 */
w->tzoff = date[-1] == '+' ? -w->tzoff : w->tzoff;
}
else if((num_digits == 8) && (w->year == -1) &&
(w->mon == -1) && (w->mday == -1)) {
/* 8 digits, no year, month or day yet. This is YYYYMMDD */
found = TRUE;
w->year = val / 10000;
w->mon = ((val % 10000) / 100) - 1; /* month is 0 - 11 */
w->mday = val % 100;
}
if(!found && (dignext == DATE_MDAY) && (w->mday == -1)) {
if((val > 0) && (val < 32)) {
w->mday = val;
found = TRUE;
}
dignext = DATE_YEAR;
}
if(!found && (dignext == DATE_YEAR) && (w->year == -1)) {
w->year = val;
found = TRUE;
if(w->year < 100) {
if(w->year > 70)
w->year += 1900;
else
w->year += 2000;
}
if(w->mday == -1)
dignext = DATE_MDAY;
}
if(!found)
return PARSEDATE_FAIL;
date = p;
}
*datep = date;
*dignextp = dignext;
return PARSEDATE_OK;
}
static int datecheck(struct when *w)
{
if(w->sec == -1)
w->sec = w->min = w->hour = 0; /* no time, make it zero */
if((w->mday == -1) || (w->mon == -1) || (w->year == -1))
/* lacks vital info, fail */
return PARSEDATE_FAIL;
/* The Gregorian calendar was introduced 1582 */
else if(w->year < 1583)
return PARSEDATE_FAIL;
else if((w->mday > 31) || (w->mon > 11) || (w->hour > 23) ||
(w->min > 59) || (w->sec > 60))
return PARSEDATE_FAIL; /* clearly an illegal date */
return PARSEDATE_OK;
}
static void tzadjust(curl_off_t *tp, struct when *w)
{
if(w->tzoff == -1) /* unknown tz means no offset */
w->tzoff = 0;
/* Add the time zone diff between local time zone and GMT. */
if((w->tzoff > 0) && (*tp > (curl_off_t)(CURL_OFF_T_MAX - w->tzoff)))
*tp = CURL_OFF_T_MAX;
else
*tp += w->tzoff;
/* this needs no minimum check since we require a year > 1582 */
}
static int mktimet(curl_off_t seconds, time_t *output)
{
#if SIZEOF_TIME_T < 5
if(seconds > TIME_T_MAX) {
*output = TIME_T_MAX;
return PARSEDATE_LATER;
}
else if(seconds < TIME_T_MIN) {
*output = TIME_T_MIN;
return PARSEDATE_SOONER;
}
#elif defined(HAVE_TIME_T_UNSIGNED)
if(seconds < 0) {
*output = 0;
return PARSEDATE_SOONER;
}
#endif
*output = (time_t)seconds;
return PARSEDATE_OK;
}
static int parsedate(const char *date, time_t *output)
{
curl_off_t seconds = 0;
enum assume dignext = DATE_MDAY;
const char *indate = date; /* save the original pointer */
int part = 0; /* max 6 parts */
int rc = 0;
struct when w;
initwhen(&w);
while(*date && (part < 6)) {
skip(&date);
if(ISALPHA(*date))
rc = datestring(&date, &w);
else if(ISDIGIT(*date))
rc = datenum(indate, &date, &w, &dignext);
if(rc)
return rc;
part++;
}
rc = datecheck(&w);
if(rc)
return rc;
seconds = time2epoch(&w); /* get number of seconds */
tzadjust(&seconds, &w); /* handle the time zone offset */
rc = mktimet(seconds, output); /* squeeze seconds into a time_t */
return rc;
}
#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 *unused)
{
time_t parsed = -1;
int rc = parsedate(p, &parsed);
(void)unused; /* 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);
}
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