1ASN1_TIME_SET(3)                    OpenSSL                   ASN1_TIME_SET(3)
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NAME

6       ASN1_TIME_set, ASN1_UTCTIME_set, ASN1_GENERALIZEDTIME_set,
7       ASN1_TIME_adj, ASN1_UTCTIME_adj, ASN1_GENERALIZEDTIME_adj,
8       ASN1_TIME_check, ASN1_UTCTIME_check, ASN1_GENERALIZEDTIME_check,
9       ASN1_TIME_set_string, ASN1_UTCTIME_set_string,
10       ASN1_GENERALIZEDTIME_set_string, ASN1_TIME_set_string_X509,
11       ASN1_TIME_normalize, ASN1_TIME_to_tm, ASN1_TIME_print,
12       ASN1_UTCTIME_print, ASN1_GENERALIZEDTIME_print, ASN1_TIME_diff,
13       ASN1_TIME_cmp_time_t, ASN1_UTCTIME_cmp_time_t, ASN1_TIME_compare,
14       ASN1_TIME_to_generalizedtime - ASN.1 Time functions
15

SYNOPSIS

17        ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t);
18        ASN1_UTCTIME *ASN1_UTCTIME_set(ASN1_UTCTIME *s, time_t t);
19        ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s,
20                                                       time_t t);
21
22        ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t, int offset_day,
23                                 long offset_sec);
24        ASN1_UTCTIME *ASN1_UTCTIME_adj(ASN1_UTCTIME *s, time_t t,
25                                       int offset_day, long offset_sec);
26        ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_adj(ASN1_GENERALIZEDTIME *s,
27                                                       time_t t, int offset_day,
28                                                       long offset_sec);
29
30        int ASN1_TIME_set_string(ASN1_TIME *s, const char *str);
31        int ASN1_TIME_set_string_X509(ASN1_TIME *s, const char *str);
32        int ASN1_UTCTIME_set_string(ASN1_UTCTIME *s, const char *str);
33        int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s,
34                                            const char *str);
35
36        int ASN1_TIME_normalize(ASN1_TIME *s);
37
38        int ASN1_TIME_check(const ASN1_TIME *t);
39        int ASN1_UTCTIME_check(const ASN1_UTCTIME *t);
40        int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *t);
41
42        int ASN1_TIME_print(BIO *b, const ASN1_TIME *s);
43        int ASN1_UTCTIME_print(BIO *b, const ASN1_UTCTIME *s);
44        int ASN1_GENERALIZEDTIME_print(BIO *b, const ASN1_GENERALIZEDTIME *s);
45
46        int ASN1_TIME_to_tm(const ASN1_TIME *s, struct tm *tm);
47        int ASN1_TIME_diff(int *pday, int *psec, const ASN1_TIME *from,
48                           const ASN1_TIME *to);
49
50        int ASN1_TIME_cmp_time_t(const ASN1_TIME *s, time_t t);
51        int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t);
52
53        int ASN1_TIME_compare(const ASN1_TIME *a, const ASN1_TIME *b);
54
55        ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t,
56                                                           ASN1_GENERALIZEDTIME **out);
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DESCRIPTION

59       The ASN1_TIME_set(), ASN1_UTCTIME_set() and ASN1_GENERALIZEDTIME_set()
60       functions set the structure s to the time represented by the time_t
61       value t. If s is NULL a new time structure is allocated and returned.
62
63       The ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_adj()
64       functions set the time structure s to the time represented by the time
65       offset_day and offset_sec after the time_t value t.  The values of
66       offset_day or offset_sec can be negative to set a time before t. The
67       offset_sec value can also exceed the number of seconds in a day. If s
68       is NULL a new structure is allocated and returned.
69
70       The ASN1_TIME_set_string(), ASN1_UTCTIME_set_string() and
71       ASN1_GENERALIZEDTIME_set_string() functions set the time structure s to
72       the time represented by string str which must be in appropriate ASN.1
73       time format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ). If s is
74       NULL this function performs a format check on str only. The string str
75       is copied into s.
76
77       ASN1_TIME_set_string_X509() sets ASN1_TIME structure s to the time
78       represented by string str which must be in appropriate time format that
79       RFC 5280 requires, which means it only allows YYMMDDHHMMSSZ and
80       YYYYMMDDHHMMSSZ (leap second is rejected), all other ASN.1 time format
81       are not allowed. If s is NULL this function performs a format check on
82       str only.
83
84       The ASN1_TIME_normalize() function converts an ASN1_GENERALIZEDTIME or
85       ASN1_UTCTIME into a time value that can be used in a certificate. It
86       should be used after the ASN1_TIME_set_string() functions and before
87       ASN1_TIME_print() functions to get consistent (i.e. GMT) results.
88
89       The ASN1_TIME_check(), ASN1_UTCTIME_check() and
90       ASN1_GENERALIZEDTIME_check() functions check the syntax of the time
91       structure s.
92
93       The ASN1_TIME_print(), ASN1_UTCTIME_print() and
94       ASN1_GENERALIZEDTIME_print() functions print the time structure s to
95       BIO b in human readable format. It will be of the format MMM DD
96       HH:MM:SS YYYY [GMT], for example "Feb  3 00:55:52 2015 GMT" it does not
97       include a newline. If the time structure has invalid format it prints
98       out "Bad time value" and returns an error. The output for generalized
99       time may include a fractional part following the second.
100
101       ASN1_TIME_to_tm() converts the time s to the standard tm structure.  If
102       s is NULL, then the current time is converted. The output time is GMT.
103       The tm_sec, tm_min, tm_hour, tm_mday, tm_wday, tm_yday, tm_mon and
104       tm_year fields of tm structure are set to proper values, whereas all
105       other fields are set to 0. If tm is NULL this function performs a
106       format check on s only. If s is in Generalized format with fractional
107       seconds, e.g. YYYYMMDDHHMMSS.SSSZ, the fractional seconds will be lost
108       while converting s to tm structure.
109
110       ASN1_TIME_diff() sets *pday and *psec to the time difference between
111       from and to. If to represents a time later than from then one or both
112       (depending on the time difference) of *pday and *psec will be positive.
113       If to represents a time earlier than from then one or both of *pday and
114       *psec will be negative. If to and from represent the same time then
115       *pday and *psec will both be zero.  If both *pday and *psec are nonzero
116       they will always have the same sign. The value of *psec will always be
117       less than the number of seconds in a day. If from or to is NULL the
118       current time is used.
119
120       The ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() functions
121       compare the two times represented by the time structure s and the
122       time_t t.
123
124       The ASN1_TIME_compare() function compares the two times represented by
125       the time structures a and b.
126
127       The ASN1_TIME_to_generalizedtime() function converts an ASN1_TIME to an
128       ASN1_GENERALIZEDTIME, regardless of year. If either out or *out are
129       NULL, then a new object is allocated and must be freed after use.
130

NOTES

132       The ASN1_TIME structure corresponds to the ASN.1 structure Time defined
133       in RFC5280 et al. The time setting functions obey the rules outlined in
134       RFC5280: if the date can be represented by UTCTime it is used, else
135       GeneralizedTime is used.
136
137       The ASN1_TIME, ASN1_UTCTIME and ASN1_GENERALIZEDTIME structures are
138       represented as an ASN1_STRING internally and can be freed up using
139       ASN1_STRING_free().
140
141       The ASN1_TIME structure can represent years from 0000 to 9999 but no
142       attempt is made to correct ancient calendar changes (for example from
143       Julian to Gregorian calendars).
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145       ASN1_UTCTIME is limited to a year range of 1950 through 2049.
146
147       Some applications add offset times directly to a time_t value and pass
148       the results to ASN1_TIME_set() (or equivalent). This can cause problems
149       as the time_t value can overflow on some systems resulting in
150       unexpected results.  New applications should use ASN1_TIME_adj()
151       instead and pass the offset value in the offset_sec and offset_day
152       parameters instead of directly manipulating a time_t value.
153
154       ASN1_TIME_adj() may change the type from ASN1_GENERALIZEDTIME to
155       ASN1_UTCTIME, or vice versa, based on the resulting year. The
156       ASN1_GENERALIZEDTIME_adj() and ASN1_UTCTIME_adj() functions will not
157       modify the type of the return structure.
158
159       It is recommended that functions starting with ASN1_TIME be used
160       instead of those starting with ASN1_UTCTIME or ASN1_GENERALIZEDTIME.
161       The functions starting with ASN1_UTCTIME and ASN1_GENERALIZEDTIME act
162       only on that specific time format. The functions starting with
163       ASN1_TIME will operate on either format.
164

BUGS

166       ASN1_TIME_print(), ASN1_UTCTIME_print() and
167       ASN1_GENERALIZEDTIME_print() do not print out the timezone: it either
168       prints out "GMT" or nothing. But all certificates complying with
169       RFC5280 et al use GMT anyway.
170
171       Use the ASN1_TIME_normalize() function to normalize the time value
172       before printing to get GMT results.
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RETURN VALUES

175       ASN1_TIME_set(), ASN1_UTCTIME_set(), ASN1_GENERALIZEDTIME_set(),
176       ASN1_TIME_adj(), ASN1_UTCTIME_adj and ASN1_GENERALIZEDTIME_set return a
177       pointer to a time structure or NULL if an error occurred.
178
179       ASN1_TIME_set_string(), ASN1_UTCTIME_set_string(),
180       ASN1_GENERALIZEDTIME_set_string() ASN1_TIME_set_string_X509() return 1
181       if the time value is successfully set and 0 otherwise.
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183       ASN1_TIME_normalize() returns 1 on success, and 0 on error.
184
185       ASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check()
186       return 1 if the structure is syntactically correct and 0 otherwise.
187
188       ASN1_TIME_print(), ASN1_UTCTIME_print() and
189       ASN1_GENERALIZEDTIME_print() return 1 if the time is successfully
190       printed out and 0 if an error occurred (I/O error or invalid time
191       format).
192
193       ASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if
194       an error occurred (invalid time format).
195
196       ASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail
197       if the passed-in time structure has invalid syntax, for example.
198
199       ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if s is
200       before t, 0 if s equals t, or 1 if s is after t. -2 is returned on
201       error.
202
203       ASN1_TIME_compare() returns -1 if a is before b, 0 if a equals b, or 1
204       if a is after b. -2 is returned on error.
205
206       ASN1_TIME_to_generalizedtime() returns a pointer to the appropriate
207       time structure on success or NULL if an error occurred.
208

EXAMPLES

210       Set a time structure to one hour after the current time and print it
211       out:
212
213        #include <time.h>
214        #include <openssl/asn1.h>
215
216        ASN1_TIME *tm;
217        time_t t;
218        BIO *b;
219
220        t = time(NULL);
221        tm = ASN1_TIME_adj(NULL, t, 0, 60 * 60);
222        b = BIO_new_fp(stdout, BIO_NOCLOSE);
223        ASN1_TIME_print(b, tm);
224        ASN1_STRING_free(tm);
225        BIO_free(b);
226
227       Determine if one time is later or sooner than the current time:
228
229        int day, sec;
230
231        if (!ASN1_TIME_diff(&day, &sec, NULL, to))
232            /* Invalid time format */
233
234        if (day > 0 || sec > 0)
235            printf("Later\n");
236        else if (day < 0 || sec < 0)
237            printf("Sooner\n");
238        else
239            printf("Same\n");
240

HISTORY

242       The ASN1_TIME_to_tm() function was added in OpenSSL 1.1.1.  The
243       ASN1_TIME_set_string_X509() function was added in OpenSSL 1.1.1.  The
244       ASN1_TIME_normalize() function was added in OpenSSL 1.1.1.  The
245       ASN1_TIME_cmp_time_t() function was added in OpenSSL 1.1.1.  The
246       ASN1_TIME_compare() function was added in OpenSSL 1.1.1.
247
249       Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
250
251       Licensed under the OpenSSL license (the "License").  You may not use
252       this file except in compliance with the License.  You can obtain a copy
253       in the file LICENSE in the source distribution or at
254       <https://www.openssl.org/source/license.html>.
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2581.1.1q                            2022-07-07                  ASN1_TIME_SET(3)
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