cosmopolitan/net/http/parsehttpdatetime.c

58 lines
3.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/bits.h"
#include "libc/time/time.h"
#include "net/http/http.h"
static unsigned ParseMonth(const char *p) {
int i;
for (i = 0; i < 12; ++i) {
if ((READ32LE(p) & 0x00ffffff) == READ32LE(kMonthNameShort[i])) {
return i + 1;
}
}
return 1;
}
/**
* Parses HTTP timestamp, e.g.
*
* Sun, 04 Oct 2020 19:50:10 GMT
*
* @return seconds from unix epoch
* @see FormatHttpDateTime()
*/
int64_t ParseHttpDateTime(const char *p, size_t n) {
unsigned weekday, year, month, day, hour, minute, second, yday, leap;
if (n != 29) return 0;
day = (p[5] - '0') * 10 + (p[6] - '0') - 1;
month = ParseMonth(p + 8);
year = (p[12] - '0') * 1000 + (p[13] - '0') * 100 + (p[14] - '0') * 10 +
(p[15] - '0') - 1900;
hour = (p[17] - '0') * 10 + (p[18] - '0');
minute = (p[20] - '0') * 10 + (p[21] - '0');
second = (p[23] - '0') * 10 + (p[24] - '0');
leap = year % 4 == 0 && (year % 100 || year % 400 == 0);
yday = day + kMonthYearDay[leap][month - 1];
return second + minute * 60 + hour * 3600 + yday * 86400 +
(year - 70) * 31536000ull + ((year - 69) / 4) * 86400ull -
((year - 1) / 100) * 86400ull + ((year + 299) / 400) * 86400ull;
}