[core] http_date.[ch] encapsulate HTTP-date parse
http_date.[ch] encapsulate HTTP-date parse/compare (import from one of my development branches from 2015)master
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/*
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* http_date - HTTP date manipulation
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*
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* Copyright(c) 2015 Glenn Strauss gstrauss()gluelogic.com All rights reserved
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* License: BSD 3-clause (same as lighttpd)
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*/
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#include "http_date.h"
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#include "sys-time.h"
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/**
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* https://tools.ietf.org/html/rfc7231
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* [RFC7231] 7.1.1.1 Date/Time Formats
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* Prior to 1995, there were three different formats commonly used by
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* servers to communicate timestamps. For compatibility with old
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* implementations, all three are defined here. The preferred format is
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* a fixed-length and single-zone subset of the date and time
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* specification used by the Internet Message Format [RFC5322].
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* HTTP-date = IMF-fixdate / obs-date
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* An example of the preferred format is
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* Sun, 06 Nov 1994 08:49:37 GMT ; IMF-fixdate
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*
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*
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* (intended for use with strftime() and strptime())
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* "%a, %d %b %Y %T GMT"
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*/
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#if defined(__CYGWIN__) && defined(__STRICT_ANSI__)
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/* (prototype for strptime() from cygwin /usr/include/time.h) */
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char *_EXFUN(strptime, (const char *__restrict,
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const char *__restrict,
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struct tm *__restrict));
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#endif
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static char *
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http_date_str_to_tm (const char * const s, struct tm * const tm)
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{
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/* attempt strptime() using multiple date formats
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* support RFC 822,1123; RFC 850; and ANSI C asctime() date strings,
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* as required by [RFC7231] https://tools.ietf.org/html/rfc7231#section-7.1
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* [RFC7231] 7.1.1.1 Date/Time Formats
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* HTTP-date = IMF-fixdate / obs-date
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* [...]
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* A recipient that parses a timestamp value in an HTTP header field
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* MUST accept all three HTTP-date formats.
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*/
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static const char *datefmts[] = {
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"%a, %d %b %Y %T GMT", /* RFC 822, RFC 1123; RFC 7231 IMF-fixdate */
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"%A, %d-%b-%y %T GMT", /* RFC 850 */
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"%a %b %d %T %Y" /* ANSI C asctime() (obsolete in POSIX.1-2008) */
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};
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char *p;
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int i = 0;
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do {
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p = strptime(s, datefmts[i], tm);
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} while (__builtin_expect( (NULL == p), 0)
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&& ++i < (int)(sizeof(datefmts)/sizeof(char *)));
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return p; /* NULL if error; date string could not be parsed */
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}
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size_t
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http_date_time_to_str (char * const s, const size_t max, const time_t t)
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{
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/*('max' is expected to be >= 30 (IMF-fixdate is 29 chars + '\0'))*/
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struct tm tm;
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return (__builtin_expect( (NULL != gmtime_r(&t, &tm)), 1))
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? strftime(s, max, "%a, %d %b %Y %T GMT", &tm) /* IMF-fixdate format */
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: 0;
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}
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#ifdef HAVE_TIMEGM
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#define http_date_timegm(tm) timegm(tm)
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#else
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#ifdef _WIN32
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#define http_date_timegm(tm) _mkgmtime(tm)
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#else
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/* If OS missing timegm(), then for best portability it is recommended to set
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* $ export LC_TIME=C TZ=UTC0
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*
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* tm->tm_isdst = 0 for mktime() to indicate daylight saving time not in effect
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* which is fine since two strings should be GMT dates, and both are converted
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* with mktime() and then the results compared */
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#define http_date_timegm(tm) ((tm)->tm_isdst = 0, mktime(tm))
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#endif
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#endif
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int
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http_date_if_modified_since (const char * const ifmod,
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const char * const lmod, time_t lmtime)
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{
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/* if caller provides non-zero lmtime, it must match Last-Modified lmod,
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* and will typically be same arg given to http_response_set_last_modified()
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* (small opt to elide one strptime(),timegm() call)
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* (In absense of timegm(), substitute mktime(), which works reasonably well
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* since mktime() strings are used for comparison of If-Modified-Since)
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* (use mktime() to convert both strings for compare) */
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struct tm ifmodtm;
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if (NULL == http_date_str_to_tm(ifmod, &ifmodtm))
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return 1; /* date parse error */
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#if defined(HAVE_TIMEGM) || defined(_WIN32)
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if (0 == lmtime)
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#endif
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{
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struct tm lmodtm;
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if (NULL == http_date_str_to_tm(lmod, &lmodtm))
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return 1; /* date parse error */
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lmtime = http_date_timegm(&lmodtm);
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}
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const time_t ifmtime = http_date_timegm(&ifmodtm);
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return (lmtime > ifmtime);
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/* returns 0 if not modified since,
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* returns 1 if modified since or date parse error */
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}
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@ -0,0 +1,29 @@
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/*
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* http_date - HTTP date manipulation
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*
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* Copyright(c) 2015 Glenn Strauss gstrauss()gluelogic.com All rights reserved
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* License: BSD 3-clause (same as lighttpd)
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*/
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#ifndef INCLUDED_HTTP_DATE_H
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#define INCLUDED_HTTP_DATE_H
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#include "first.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define HTTP_DATE_SZ 30 /* (IMF-fixdate is 29 chars + '\0') */
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size_t http_date_time_to_str (char *s, size_t max, time_t t);
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int http_date_if_modified_since (const char *ifmod, const char *lmod, time_t lmtime);
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#ifdef __cplusplus
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}
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#endif
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#endif
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