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.\" ========================================================================
.\"
.IX Title "ASN1_TIME_set 3"
.TH ASN1_TIME_set 3 "2023-05-07" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "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_TIME_print_ex, 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,
ASN1_TIME_dup, ASN1_UTCTIME_dup, ASN1_GENERALIZEDTIME_dup \- ASN.1 Time functions
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 4
\& 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_TIME_print_ex(BIO *bp, const ASN1_TIME *tm, unsigned long flags);
\& 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);
\&
\& ASN1_TIME *ASN1_TIME_dup(const ASN1_TIME *t);
\& ASN1_UTCTIME *ASN1_UTCTIME_dup(const ASN1_UTCTIME *t);
\& ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_dup(const ASN1_GENERALIZEDTIME *t);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fBASN1_TIME_set()\fR, \fBASN1_UTCTIME_set()\fR and \fBASN1_GENERALIZEDTIME_set()\fR
functions set the structure \fIs\fR to the time represented by the time_t
value \fIt\fR. If \fIs\fR is \s-1NULL\s0 a new time structure is allocated and returned.
.PP
The \fBASN1_TIME_adj()\fR, \fBASN1_UTCTIME_adj()\fR and \fBASN1_GENERALIZEDTIME_adj()\fR
functions set the time structure \fIs\fR to the time represented
by the time \fIoffset_day\fR and \fIoffset_sec\fR after the time_t value \fIt\fR.
The values of \fIoffset_day\fR or \fIoffset_sec\fR can be negative to set a
time before \fIt\fR. The \fIoffset_sec\fR value can also exceed the number of
seconds in a day. If \fIs\fR is \s-1NULL\s0 a new structure is allocated
and returned.
.PP
The \fBASN1_TIME_set_string()\fR, \fBASN1_UTCTIME_set_string()\fR and
\&\fBASN1_GENERALIZEDTIME_set_string()\fR functions set the time structure \fIs\fR
to the time represented by string \fIstr\fR which must be in appropriate \s-1ASN.1\s0
time format (for example \s-1YYMMDDHHMMSSZ\s0 or \s-1YYYYMMDDHHMMSSZ\s0). If \fIs\fR is \s-1NULL\s0
this function performs a format check on \fIstr\fR only. The string \fIstr\fR
is copied into \fIs\fR.
.PP
\&\fBASN1_TIME_set_string_X509()\fR sets \fB\s-1ASN1_TIME\s0\fR structure \fIs\fR to the time
represented by string \fIstr\fR which must be in appropriate time format
that \s-1RFC 5280\s0 requires, which means it only allows \s-1YYMMDDHHMMSSZ\s0 and
\&\s-1YYYYMMDDHHMMSSZ\s0 (leap second is rejected), all other \s-1ASN.1\s0 time format
are not allowed. If \fIs\fR is \s-1NULL\s0 this function performs a format check
on \fIstr\fR only.
.PP
The \fBASN1_TIME_normalize()\fR function converts an \fB\s-1ASN1_GENERALIZEDTIME\s0\fR or
\&\fB\s-1ASN1_UTCTIME\s0\fR into a time value that can be used in a certificate. It
should be used after the \fBASN1_TIME_set_string()\fR functions and before
\&\fBASN1_TIME_print()\fR functions to get consistent (i.e. \s-1GMT\s0) results.
.PP
The \fBASN1_TIME_check()\fR, \fBASN1_UTCTIME_check()\fR and \fBASN1_GENERALIZEDTIME_check()\fR
functions check the syntax of the time structure \fIs\fR.
.PP
The \fBASN1_TIME_print()\fR, \fBASN1_UTCTIME_print()\fR and \fBASN1_GENERALIZEDTIME_print()\fR
functions print the time structure \fIs\fR to \s-1BIO\s0 \fIb\fR in human readable
format. It will be of the format \s-1MMM DD HH:MM:SS YYYY\s0 [\s-1GMT\s0], for example
\&\*(L"Feb 3 00:55:52 2015 \s-1GMT\*(R",\s0 which does not include a newline.
If the time structure has invalid format it prints out \*(L"Bad time value\*(R" and
returns an error. The output for generalized time may include a fractional part
following the second.
.PP
\&\fBASN1_TIME_print_ex()\fR provides \fIflags\fR to specify the output format of the
datetime. This can be either \fB\s-1ASN1_DTFLGS_RFC822\s0\fR or \fB\s-1ASN1_DTFLGS_ISO8601\s0\fR.
.PP
\&\fBASN1_TIME_to_tm()\fR converts the time \fIs\fR to the standard \fItm\fR structure.
If \fIs\fR is \s-1NULL,\s0 then the current time is converted. The output time is \s-1GMT.\s0
The \fItm_sec\fR, \fItm_min\fR, \fItm_hour\fR, \fItm_mday\fR, \fItm_wday\fR, \fItm_yday\fR,
\&\fItm_mon\fR and \fItm_year\fR fields of \fItm\fR structure are set to proper values,
whereas all other fields are set to 0. If \fItm\fR is \s-1NULL\s0 this function performs
a format check on \fIs\fR only. If \fIs\fR is in Generalized format with fractional
seconds, e.g. \s-1YYYYMMDDHHMMSS.SSSZ,\s0 the fractional seconds will be lost while
converting \fIs\fR to \fItm\fR structure.
.PP
\&\fBASN1_TIME_diff()\fR sets \fI*pday\fR and \fI*psec\fR to the time difference between
\&\fIfrom\fR and \fIto\fR. If \fIto\fR represents a time later than \fIfrom\fR then
one or both (depending on the time difference) of \fI*pday\fR and \fI*psec\fR
will be positive. If \fIto\fR represents a time earlier than \fIfrom\fR then
one or both of \fI*pday\fR and \fI*psec\fR will be negative. If \fIto\fR and \fIfrom\fR
represent the same time then \fI*pday\fR and \fI*psec\fR will both be zero.
If both \fI*pday\fR and \fI*psec\fR are nonzero they will always have the same
sign. The value of \fI*psec\fR will always be less than the number of seconds
in a day. If \fIfrom\fR or \fIto\fR is \s-1NULL\s0 the current time is used.
.PP
The \fBASN1_TIME_cmp_time_t()\fR and \fBASN1_UTCTIME_cmp_time_t()\fR functions compare
the two times represented by the time structure \fIs\fR and the time_t \fIt\fR.
.PP
The \fBASN1_TIME_compare()\fR function compares the two times represented by the
time structures \fIa\fR and \fIb\fR.
.PP
The \fBASN1_TIME_to_generalizedtime()\fR function converts an \fB\s-1ASN1_TIME\s0\fR to an
\&\fB\s-1ASN1_GENERALIZEDTIME\s0\fR, regardless of year. If either \fIout\fR or
\&\fI*out\fR are \s-1NULL,\s0 then a new object is allocated and must be freed after use.
.PP
The \fBASN1_TIME_dup()\fR, \fBASN1_UTCTIME_dup()\fR and \fBASN1_GENERALIZEDTIME_dup()\fR functions
duplicate the time structure \fIt\fR and return the duplicated result
correspondingly.
.SH "NOTES"
.IX Header "NOTES"
The \fB\s-1ASN1_TIME\s0\fR structure corresponds to the \s-1ASN.1\s0 structure \fBTime\fR
defined in \s-1RFC5280\s0 et al. The time setting functions obey the rules outlined
in \s-1RFC5280:\s0 if the date can be represented by UTCTime it is used, else
GeneralizedTime is used.
.PP
The \fB\s-1ASN1_TIME\s0\fR, \fB\s-1ASN1_UTCTIME\s0\fR and \fB\s-1ASN1_GENERALIZEDTIME\s0\fR structures are
represented as an \fB\s-1ASN1_STRING\s0\fR internally and can be freed up using
\&\fBASN1_STRING_free()\fR.
.PP
The \fB\s-1ASN1_TIME\s0\fR 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).
.PP
\&\fB\s-1ASN1_UTCTIME\s0\fR is limited to a year range of 1950 through 2049.
.PP
Some applications add offset times directly to a time_t value and pass the
results to \fBASN1_TIME_set()\fR (or equivalent). This can cause problems as the
time_t value can overflow on some systems resulting in unexpected results.
New applications should use \fBASN1_TIME_adj()\fR instead and pass the offset value
in the \fIoffset_sec\fR and \fIoffset_day\fR parameters instead of directly
manipulating a time_t value.
.PP
\&\fBASN1_TIME_adj()\fR may change the type from \fB\s-1ASN1_GENERALIZEDTIME\s0\fR to
\&\fB\s-1ASN1_UTCTIME\s0\fR, or vice versa, based on the resulting year.
\&\fBASN1_GENERALIZEDTIME_adj()\fR and \fBASN1_UTCTIME_adj()\fR will not modify the type
of the return structure.
.PP
It is recommended that functions starting with \fB\s-1ASN1_TIME\s0\fR be used instead of
those starting with \fB\s-1ASN1_UTCTIME\s0\fR or \fB\s-1ASN1_GENERALIZEDTIME\s0\fR. The functions
starting with \fB\s-1ASN1_UTCTIME\s0\fR and \fB\s-1ASN1_GENERALIZEDTIME\s0\fR act only on that
specific time format. The functions starting with \fB\s-1ASN1_TIME\s0\fR will operate on
either format.
.SH "BUGS"
.IX Header "BUGS"
\&\fBASN1_TIME_print()\fR, \fBASN1_UTCTIME_print()\fR and \fBASN1_GENERALIZEDTIME_print()\fR do
not print out the timezone: it either prints out \*(L"\s-1GMT\*(R"\s0 or nothing. But all
certificates complying with \s-1RFC5280\s0 et al use \s-1GMT\s0 anyway.
.PP
\&\fBASN1_TIME_print()\fR, \fBASN1_TIME_print_ex()\fR, \fBASN1_UTCTIME_print()\fR and
\&\fBASN1_GENERALIZEDTIME_print()\fR do not distinguish if they fail because
of an I/O error or invalid time format.
.PP
Use the \fBASN1_TIME_normalize()\fR function to normalize the time value before
printing to get \s-1GMT\s0 results.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBASN1_TIME_set()\fR, \fBASN1_UTCTIME_set()\fR, \fBASN1_GENERALIZEDTIME_set()\fR,
\&\fBASN1_TIME_adj()\fR, \fBASN1_UTCTIME_adj()\fR and \fBASN1_GENERALIZEDTIME_set()\fR return
a pointer to a time structure or \s-1NULL\s0 if an error occurred.
.PP
\&\fBASN1_TIME_set_string()\fR, \fBASN1_UTCTIME_set_string()\fR,
\&\fBASN1_GENERALIZEDTIME_set_string()\fR and \fBASN1_TIME_set_string_X509()\fR return
1 if the time value is successfully set and 0 otherwise.
.PP
\&\fBASN1_TIME_normalize()\fR returns 1 on success, and 0 on error.
.PP
\&\fBASN1_TIME_check()\fR, ASN1_UTCTIME_check and \fBASN1_GENERALIZEDTIME_check()\fR return 1
if the structure is syntactically correct and 0 otherwise.
.PP
\&\fBASN1_TIME_print()\fR, \fBASN1_UTCTIME_print()\fR and \fBASN1_GENERALIZEDTIME_print()\fR
return 1 if the time is successfully printed out and
0 if an I/O error occurred an error occurred (I/O error or invalid time format).
.PP
\&\fBASN1_TIME_to_tm()\fR returns 1 if the time is successfully parsed and 0 if an
error occurred (invalid time format).
.PP
\&\fBASN1_TIME_diff()\fR returns 1 for success and 0 for failure. It can fail if the
passed-in time structure has invalid syntax, for example.
.PP
\&\fBASN1_TIME_cmp_time_t()\fR and \fBASN1_UTCTIME_cmp_time_t()\fR return \-1 if \fIs\fR is
before \fIt\fR, 0 if \fIs\fR equals \fIt\fR, or 1 if \fIs\fR is after \fIt\fR. \-2 is returned
on error.
.PP
\&\fBASN1_TIME_compare()\fR returns \-1 if \fIa\fR is before \fIb\fR, 0 if \fIa\fR equals \fIb\fR,
or 1 if \fIa\fR is after \fIb\fR. \-2 is returned on error.
.PP
\&\fBASN1_TIME_to_generalizedtime()\fR returns a pointer to the appropriate time
structure on success or \s-1NULL\s0 if an error occurred.
.PP
\&\fBASN1_TIME_dup()\fR, \fBASN1_UTCTIME_dup()\fR and \fBASN1_GENERALIZEDTIME_dup()\fR return a
pointer to a time structure or \s-1NULL\s0 if an error occurred.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
Set a time structure to one hour after the current time and print it out:
.PP
.Vb 2
\& #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);
.Ve
.PP
Determine if one time is later or sooner than the current time:
.PP
.Vb 1
\& int day, sec;
\&
\& if (!ASN1_TIME_diff(&day, &sec, NULL, to))
\& /* Invalid time format */
\&
\& if (day > 0 || sec > 0)
\& printf("Later\en");
\& else if (day < 0 || sec < 0)
\& printf("Sooner\en");
\& else
\& printf("Same\en");
.Ve
.SH "HISTORY"
.IX Header "HISTORY"
The \fBASN1_TIME_to_tm()\fR function was added in OpenSSL 1.1.1.
The \fBASN1_TIME_set_string_X509()\fR function was added in OpenSSL 1.1.1.
The \fBASN1_TIME_normalize()\fR function was added in OpenSSL 1.1.1.
The \fBASN1_TIME_cmp_time_t()\fR function was added in OpenSSL 1.1.1.
The \fBASN1_TIME_compare()\fR function was added in OpenSSL 1.1.1.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2015\-2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.