ASN1_TIME_SET(3) OpenSSL ASN1_TIME_SET(3)
NAME
ASN1_TIME_set, ASN1_UTCTIME_set, ASN1_GENERALIZEDTIME_set,
ASN1_TIME_adj, ASN1_UTCTIME_adj, ASN1_GENERALIZEDTIME_adj,
ASN1_TIME_check, ASN1_UTCTIME_check, ASN1_GENERALIZEDTIME_check,
ASN1_TIME_set_string, ASN1_UTCTIME_set_string,
ASN1_GENERALIZEDTIME_set_string, ASN1_TIME_set_string_X509,
ASN1_TIME_normalize, ASN1_TIME_to_tm, ASN1_TIME_print,
ASN1_UTCTIME_print, ASN1_GENERALIZEDTIME_print, ASN1_TIME_diff,
ASN1_TIME_cmp_time_t, ASN1_UTCTIME_cmp_time_t, ASN1_TIME_compare,
ASN1_TIME_to_generalizedtime - ASN.1 Time functions
SYNOPSIS
ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t);
ASN1_UTCTIME *ASN1_UTCTIME_set(ASN1_UTCTIME *s, time_t t);
ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s,
time_t t);
ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t, int offset_day,
long offset_sec);
ASN1_UTCTIME *ASN1_UTCTIME_adj(ASN1_UTCTIME *s, time_t t,
int offset_day, long offset_sec);
ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_adj(ASN1_GENERALIZEDTIME *s,
time_t t, int offset_day,
long offset_sec);
int ASN1_TIME_set_string(ASN1_TIME *s, const char *str);
int ASN1_TIME_set_string_X509(ASN1_TIME *s, const char *str);
int ASN1_UTCTIME_set_string(ASN1_UTCTIME *s, const char *str);
int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s,
const char *str);
int ASN1_TIME_normalize(ASN1_TIME *s);
int ASN1_TIME_check(const ASN1_TIME *t);
int ASN1_UTCTIME_check(const ASN1_UTCTIME *t);
int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *t);
int ASN1_TIME_print(BIO *b, const ASN1_TIME *s);
int ASN1_UTCTIME_print(BIO *b, const ASN1_UTCTIME *s);
int ASN1_GENERALIZEDTIME_print(BIO *b, const ASN1_GENERALIZEDTIME *s);
int ASN1_TIME_to_tm(const ASN1_TIME *s, struct tm *tm);
int ASN1_TIME_diff(int *pday, int *psec, const ASN1_TIME *from,
const ASN1_TIME *to);
int ASN1_TIME_cmp_time_t(const ASN1_TIME *s, time_t t);
int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t);
int ASN1_TIME_compare(const ASN1_TIME *a, const ASN1_TIME *b);
ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t,
ASN1_GENERALIZEDTIME **out);
DESCRIPTION
The ASN1_TIME_set(), ASN1_UTCTIME_set() and ASN1_GENERALIZEDTIME_set()
functions set the structure s to the time represented by the time_t
value t. If s is NULL a new time structure is allocated and returned.
The ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_adj()
functions set the time structure s to the time represented by the time
offset_day and offset_sec after the time_t value t. The values of
offset_day or offset_sec can be negative to set a time before t. The
offset_sec value can also exceed the number of seconds in a day. If s
is NULL a new structure is allocated and returned.
The ASN1_TIME_set_string(), ASN1_UTCTIME_set_string() and
ASN1_GENERALIZEDTIME_set_string() functions set the time structure s to
the time represented by string str which must be in appropriate ASN.1
time format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ). If s is
NULL this function performs a format check on str only. The string str
is copied into s.
ASN1_TIME_set_string_X509() sets ASN1_TIME structure s to the time
represented by string str which must be in appropriate time format that
RFC 5280 requires, which means it only allows YYMMDDHHMMSSZ and
YYYYMMDDHHMMSSZ (leap second is rejected), all other ASN.1 time format
are not allowed. If s is NULL this function performs a format check on
str only.
The ASN1_TIME_normalize() function converts an ASN1_GENERALIZEDTIME or
ASN1_UTCTIME into a time value that can be used in a certificate. It
should be used after the ASN1_TIME_set_string() functions and before
ASN1_TIME_print() functions to get consistent (i.e. GMT) results.
The ASN1_TIME_check(), ASN1_UTCTIME_check() and
ASN1_GENERALIZEDTIME_check() functions check the syntax of the time
structure s.
The ASN1_TIME_print(), ASN1_UTCTIME_print() and
ASN1_GENERALIZEDTIME_print() functions print the time structure s to
BIO b in human readable format. It will be of the format MMM DD
HH:MM:SS YYYY [GMT], for example "Feb 3 00:55:52 2015 GMT" it does not
include a newline. If the time structure has invalid format it prints
out "Bad time value" and returns an error. The output for generalized
time may include a fractional part following the second.
ASN1_TIME_to_tm() converts the time s to the standard tm structure. If
s is NULL, then the current time is converted. The output time is GMT.
The tm_sec, tm_min, tm_hour, tm_mday, tm_wday, tm_yday, tm_mon and
tm_year fields of tm structure are set to proper values, whereas all
other fields are set to 0. If tm is NULL this function performs a
format check on s only. If s is in Generalized format with fractional
seconds, e.g. YYYYMMDDHHMMSS.SSSZ, the fractional seconds will be lost
while converting s to tm structure.
ASN1_TIME_diff() sets *pday and *psec to the time difference between
from and to. If to represents a time later than from then one or both
(depending on the time difference) of *pday and *psec will be positive.
If to represents a time earlier than from then one or both of *pday and
*psec will be negative. If to and from represent the same time then
*pday and *psec will both be zero. If both *pday and *psec are nonzero
they will always have the same sign. The value of *psec will always be
less than the number of seconds in a day. If from or to is NULL the
current time is used.
The ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() functions
compare the two times represented by the time structure s and the
time_t t.
The ASN1_TIME_compare() function compares the two times represented by
the time structures a and b.
The ASN1_TIME_to_generalizedtime() function converts an ASN1_TIME to an
ASN1_GENERALIZEDTIME, regardless of year. If either out or *out are
NULL, then a new object is allocated and must be freed after use.
NOTES
The ASN1_TIME structure corresponds to the ASN.1 structure Time defined
in RFC5280 et al. The time setting functions obey the rules outlined in
RFC5280: if the date can be represented by UTCTime it is used, else
GeneralizedTime is used.
The ASN1_TIME, ASN1_UTCTIME and ASN1_GENERALIZEDTIME structures are
represented as an ASN1_STRING internally and can be freed up using
ASN1_STRING_free().
The ASN1_TIME structure can represent years from 0000 to 9999 but no
attempt is made to correct ancient calendar changes (for example from
Julian to Gregorian calendars).
ASN1_UTCTIME is limited to a year range of 1950 through 2049.
Some applications add offset times directly to a time_t value and pass
the results to ASN1_TIME_set() (or equivalent). This can cause problems
as the time_t value can overflow on some systems resulting in
unexpected results. New applications should use ASN1_TIME_adj()
instead and pass the offset value in the offset_sec and offset_day
parameters instead of directly manipulating a time_t value.
ASN1_TIME_adj() may change the type from ASN1_GENERALIZEDTIME to
ASN1_UTCTIME, or vice versa, based on the resulting year. The
ASN1_GENERALIZEDTIME_adj() and ASN1_UTCTIME_adj() functions will not
modify the type of the return structure.
It is recommended that functions starting with ASN1_TIME be used
instead of those starting with ASN1_UTCTIME or ASN1_GENERALIZEDTIME.
The functions starting with ASN1_UTCTIME and ASN1_GENERALIZEDTIME act
only on that specific time format. The functions starting with
ASN1_TIME will operate on either format.
BUGS
ASN1_TIME_print(), ASN1_UTCTIME_print() and
ASN1_GENERALIZEDTIME_print() do not print out the timezone: it either
prints out "GMT" or nothing. But all certificates complying with
RFC5280 et al use GMT anyway.
Use the ASN1_TIME_normalize() function to normalize the time value
before printing to get GMT results.
RETURN VALUES
ASN1_TIME_set(), ASN1_UTCTIME_set(), ASN1_GENERALIZEDTIME_set(),
ASN1_TIME_adj(), ASN1_UTCTIME_adj and ASN1_GENERALIZEDTIME_set return a
pointer to a time structure or NULL if an error occurred.
ASN1_TIME_set_string(), ASN1_UTCTIME_set_string(),
ASN1_GENERALIZEDTIME_set_string() ASN1_TIME_set_string_X509() return 1
if the time value is successfully set and 0 otherwise.
ASN1_TIME_normalize() returns 1 on success, and 0 on error.
ASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check()
return 1 if the structure is syntactically correct and 0 otherwise.
ASN1_TIME_print(), ASN1_UTCTIME_print() and
ASN1_GENERALIZEDTIME_print() return 1 if the time is successfully
printed out and 0 if an error occurred (I/O error or invalid time
format).
ASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if
an error occurred (invalid time format).
ASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail
if the passed-in time structure has invalid syntax, for example.
ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if s is
before t, 0 if s equals t, or 1 if s is after t. -2 is returned on
error.
ASN1_TIME_compare() returns -1 if a is before b, 0 if a equals b, or 1
if a is after b. -2 is returned on error.
ASN1_TIME_to_generalizedtime() returns a pointer to the appropriate
time structure on success or NULL if an error occurred.
EXAMPLES
Set a time structure to one hour after the current time and print it
out:
#include <time.h>
#include <openssl/asn1.h>
ASN1_TIME *tm;
time_t t;
BIO *b;
t = time(NULL);
tm = ASN1_TIME_adj(NULL, t, 0, 60 * 60);
b = BIO_new_fp(stdout, BIO_NOCLOSE);
ASN1_TIME_print(b, tm);
ASN1_STRING_free(tm);
BIO_free(b);
Determine if one time is later or sooner than the current time:
int day, sec;
if (!ASN1_TIME_diff(&day, &sec, NULL, to))
/* Invalid time format */
if (day > 0 || sec > 0)
printf("Later\n");
else if (day < 0 || sec < 0)
printf("Sooner\n");
else
printf("Same\n");
HISTORY
The ASN1_TIME_to_tm() function was added in OpenSSL 1.1.1. The
ASN1_TIME_set_string_X509() function was added in OpenSSL 1.1.1. The
ASN1_TIME_normalize() function was added in OpenSSL 1.1.1. The
ASN1_TIME_cmp_time_t() function was added in OpenSSL 1.1.1. The
ASN1_TIME_compare() function was added in OpenSSL 1.1.1.
COPYRIGHT
Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>;.
1.1.1k 2021-03-25 ASN1_TIME_SET(3)
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