curl/lib/parsedate.c
Eric Lubin 7246dffff5 parsedate: avoid integer overflow
In C, signed integer overflow is undefined behavior. Thus, the compiler
is allowed to assume that it will not occur. In the check for an
overflow, the developer assumes that the signed integer of type time_t
will wrap around if it overflows. However, this behavior is undefined in
the C standard. Thus, when the compiler sees this, it simplifies t +
delta < t to delta < 0. Since delta > 0 and delta < 0 can't both be
true, the entire if statement is optimized out under certain
optimization levels. Thus, the parsedate function would return
PARSEDATE_OK with an undefined value in the time, instead of return -1 =
PARSEDATE_FAIL.
2013-12-11 16:32:21 +01:00

581 lines
16 KiB
C

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2013, 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 http://curl.haxx.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.
*
***************************************************************************/
/*
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
*/
#include "curl_setup.h"
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#include <curl/curl.h>
#include "rawstr.h"
#include "warnless.h"
#include "parsedate.h"
const char * const Curl_wkday[] =
{"Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"};
static const char * const weekday[] =
{ "Monday", "Tuesday", "Wednesday", "Thursday",
"Friday", "Saturday", "Sunday" };
const char * const Curl_month[]=
{ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
struct tzinfo {
char name[5];
int offset; /* +/- in minutes */
};
/*
* 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
*/
static int parsedate(const char *date, time_t *output);
#define PARSEDATE_OK 0
#define PARSEDATE_FAIL -1
#define PARSEDATE_LATER 1
#define PARSEDATE_SOONER 2
/* 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 */
{"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 */
{"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}, /* 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;
bool found= FALSE;
if(len > 3)
what = &weekday[0];
else
what = &Curl_wkday[0];
for(i=0; i<7; i++) {
if(Curl_raw_equal(check, what[0])) {
found=TRUE;
break;
}
what++;
}
return found?i:-1;
}
static int checkmonth(const char *check)
{
int i;
const char * const *what;
bool found= FALSE;
what = &Curl_month[0];
for(i=0; i<12; i++) {
if(Curl_raw_equal(check, what[0])) {
found=TRUE;
break;
}
what++;
}
return found?i:-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 wasn't found/legal */
static int checktz(const char *check)
{
unsigned int i;
const struct tzinfo *what;
bool found= FALSE;
what = tz;
for(i=0; i< sizeof(tz)/sizeof(tz[0]); i++) {
if(Curl_raw_equal(check, what->name)) {
found=TRUE;
break;
}
what++;
}
return found?what->offset*60:-1;
}
static void skip(const char **date)
{
/* skip everything that aren't letters or digits */
while(**date && !ISALNUM(**date))
(*date)++;
}
enum assume {
DATE_MDAY,
DATE_YEAR,
DATE_TIME
};
/* this is a clone of 'struct tm' but with all fields we don't need or use
cut out */
struct my_tm {
int tm_sec;
int tm_min;
int tm_hour;
int tm_mday;
int tm_mon;
int tm_year;
};
/* struct tm to time since epoch in GMT time zone.
* This is similar to the standard mktime function but for GMT only, and
* doesn't suffer from the various bugs and portability problems that
* some systems' implementations have.
*/
static time_t my_timegm(struct my_tm *tm)
{
static const int month_days_cumulative [12] =
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
int month, year, leap_days;
if(tm->tm_year < 70)
/* we don't support years before 1970 as they will cause this function
to return a negative value */
return -1;
year = tm->tm_year + 1900;
month = tm->tm_mon;
if(month < 0) {
year += (11 - month) / 12;
month = 11 - (11 - month) % 12;
}
else if(month >= 12) {
year -= month / 12;
month = month % 12;
}
leap_days = year - (tm->tm_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 [month] + tm->tm_mday - 1) * 24
+ tm->tm_hour) * 60 + tm->tm_min) * 60 + tm->tm_sec;
}
/*
* 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
*/
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;
struct my_tm tm;
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 */
char buf[32]="";
size_t len;
sscanf(date, "%31[ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz]",
buf);
len = strlen(buf);
if(wdaynum == -1) {
wdaynum = checkday(buf, len);
if(wdaynum != -1)
found = TRUE;
}
if(!found && (monnum == -1)) {
monnum = checkmonth(buf);
if(monnum != -1)
found = TRUE;
}
if(!found && (tzoff == -1)) {
/* this just must be a time zone string */
tzoff = checktz(buf);
if(tzoff != -1)
found = TRUE;
}
if(!found)
return PARSEDATE_FAIL; /* bad string */
date += len;
}
else if(ISDIGIT(*date)) {
/* a digit */
int val;
char *end;
if((secnum == -1) &&
(3 == sscanf(date, "%02d:%02d:%02d", &hournum, &minnum, &secnum))) {
/* time stamp! */
date += 8;
}
else if((secnum == -1) &&
(2 == sscanf(date, "%02d:%02d", &hournum, &minnum))) {
/* time stamp without seconds */
date += 5;
secnum = 0;
}
else {
long lval;
int error;
int old_errno;
old_errno = ERRNO;
SET_ERRNO(0);
lval = strtol(date, &end, 10);
error = ERRNO;
if(error != old_errno)
SET_ERRNO(old_errno);
if(error)
return PARSEDATE_FAIL;
if((lval > (long)INT_MAX) || (lval < (long)INT_MIN))
return PARSEDATE_FAIL;
val = curlx_sltosi(lval);
if((tzoff == -1) &&
((end - date) == 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 ther reversed math to get what we want */
tzoff = date[-1]=='+'?-tzoff:tzoff;
}
if(((end - date) == 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 < 1900) {
if(yearnum > 70)
yearnum += 1900;
else
yearnum += 2000;
}
if(mdaynum == -1)
dignext = DATE_MDAY;
}
if(!found)
return PARSEDATE_FAIL;
date = end;
}
}
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;
#if SIZEOF_TIME_T < 5
/* 32 bit time_t can only hold dates to the beginning of 2038 */
if(yearnum > 2037) {
*output = 0x7fffffff;
return PARSEDATE_LATER;
}
#endif
if(yearnum < 1970) {
*output = 0;
return PARSEDATE_SOONER;
}
if((mdaynum > 31) || (monnum > 11) ||
(hournum > 23) || (minnum > 59) || (secnum > 60))
return PARSEDATE_FAIL; /* clearly an illegal date */
tm.tm_sec = secnum;
tm.tm_min = minnum;
tm.tm_hour = hournum;
tm.tm_mday = mdaynum;
tm.tm_mon = monnum;
tm.tm_year = yearnum - 1900;
/* my_timegm() returns a time_t. time_t is often 32 bits, even on many
architectures that feature 64 bit 'long'.
Some systems have 64 bit time_t and deal with years beyond 2038. However,
even on some of the systems with 64 bit time_t mktime() returns -1 for
dates beyond 03:14:07 UTC, January 19, 2038. (Such as AIX 5100-06)
*/
t = my_timegm(&tm);
/* time zone adjust (cast t to int to compare to negative one) */
if(-1 != (int)t) {
/* Add the time zone diff between local time zone and GMT. */
long delta = (long)(tzoff!=-1?tzoff:0);
if((delta>0) && (t > LONG_MAX - delta))
return -1; /* time_t overflow */
t += delta;
}
*output = t;
return PARSEDATE_OK;
}
time_t curl_getdate(const char *p, const time_t *now)
{
time_t parsed;
int rc = parsedate(p, &parsed);
(void)now; /* legacy argument from the past that we ignore */
switch(rc) {
case PARSEDATE_OK:
case PARSEDATE_LATER:
case PARSEDATE_SOONER:
return parsed;
}
/* everything else is fail */
return -1;
}
/*
* Curl_gmtime() is a gmtime() replacement for portability. Do not use the
* gmtime_r() or gmtime() functions anywhere else but here.
*
* To make sure no such function calls slip in, we define them to cause build
* errors, which is why we use the name within parentheses in this function.
*
*/
CURLcode Curl_gmtime(time_t intime, struct tm *store)
{
const struct tm *tm;
#ifdef HAVE_GMTIME_R
/* thread-safe version */
tm = (struct tm *)gmtime_r(&intime, store);
#else
tm = gmtime(&intime);
if(tm)
*store = *tm; /* copy the pointed struct to the local copy */
#endif
if(!tm)
return CURLE_BAD_FUNCTION_ARGUMENT;
return CURLE_OK;
}