5 ASN1_TIME_set, ASN1_TIME_adj, ASN1_TIME_check, ASN1_TIME_set_string,
6 ASN1_TIME_print, ASN1_TIME_diff - ASN.1 Time functions.
10 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t);
11 ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t,
12 int offset_day, long offset_sec);
13 int ASN1_TIME_set_string(ASN1_TIME *s, const char *str);
14 int ASN1_TIME_check(const ASN1_TIME *t);
15 int ASN1_TIME_print(BIO *b, const ASN1_TIME *s);
17 int ASN1_TIME_diff(int *pday, int *psec,
18 const ASN1_TIME *from, const ASN1_TIME *to);
22 The function ASN1_TIME_set() sets the ASN1_TIME structure B<s> to the
23 time represented by the time_t value B<t>. If B<s> is NULL a new ASN1_TIME
24 structure is allocated and returned.
26 ASN1_TIME_adj() sets the ASN1_TIME structure B<s> to the time represented
27 by the time B<offset_day> and B<offset_sec> after the time_t value B<t>.
28 The values of B<offset_day> or B<offset_sec> can be negative to set a
29 time before B<t>. The B<offset_sec> value can also exceed the number of
30 seconds in a day. If B<s> is NULL a new ASN1_TIME structure is allocated
33 ASN1_TIME_set_string() sets ASN1_TIME structure B<s> to the time
34 represented by string B<str> which must be in appropriate ASN.1 time
35 format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ).
37 ASN1_TIME_check() checks the syntax of ASN1_TIME structure B<s>.
39 ASN1_TIME_print() prints out the time B<s> to BIO B<b> in human readable
40 format. It will be of the format MMM DD HH:MM:SS YYYY [GMT], for example
41 "Feb 3 00:55:52 2015 GMT" it does not include a newline. If the time
42 structure has invalid format it prints out "Bad time value" and returns
45 ASN1_TIME_diff() sets B<*pday> and B<*psec> to the time difference between
46 B<from> and B<to>. If B<to> represents a time later than B<from> then
47 one or both (depending on the time difference) of B<*pday> and B<*psec>
48 will be positive. If B<to> represents a time earlier than B<from> then
49 one or both of B<*pday> and B<*psec> will be negative. If B<to> and B<from>
50 represent the same time then B<*pday> and B<*psec> will both be zero.
51 If both B<*pday> and B<*psec> are non-zero they will always have the same
52 sign. The value of B<*psec> will always be less than the number of seconds
53 in a day. If B<from> or B<to> is NULL the current time is used.
57 The ASN1_TIME structure corresponds to the ASN.1 structure B<Time>
58 defined in RFC5280 et al. The time setting functions obey the rules outlined
59 in RFC5280: if the date can be represented by UTCTime it is used, else
60 GeneralizedTime is used.
62 The ASN1_TIME structure is represented as an ASN1_STRING internally and can
63 be freed up using ASN1_STRING_free().
65 The ASN1_TIME structure can represent years from 0000 to 9999 but no attempt
66 is made to correct ancient calendar changes (for example from Julian to
69 Some applications add offset times directly to a time_t value and pass the
70 results to ASN1_TIME_set() (or equivalent). This can cause problems as the
71 time_t value can overflow on some systems resulting in unexpected results.
72 New applications should use ASN1_TIME_adj() instead and pass the offset value
73 in the B<offset_sec> and B<offset_day> parameters instead of directly
74 manipulating a time_t value.
78 ASN1_TIME_print() currently does not print out the time zone: it either prints
79 out "GMT" or nothing. But all certificates complying with RFC5280 et al use GMT
84 Set a time structure to one hour after the current time and print it out:
87 #include <openssl/asn1.h>
92 tm = ASN1_TIME_adj(NULL, t, 0, 60 * 60);
93 b = BIO_new_fp(stdout, BIO_NOCLOSE);
94 ASN1_TIME_print(b, tm);
98 Determine if one time is later or sooner than the current time:
102 if (!ASN1_TIME_diff(&day, &sec, NULL, to))
103 /* Invalid time format */
105 if (day > 0 || sec > 0)
107 else if (day < 0 || sec < 0)
114 ASN1_TIME_set() and ASN1_TIME_adj() return a pointer to an ASN1_TIME structure
115 or NULL if an error occurred.
117 ASN1_TIME_set_string() returns 1 if the time value is successfully set and
120 ASN1_TIME_check() returns 1 if the structure is syntactically correct and 0
123 ASN1_TIME_print() returns 1 if the time is successfully printed out and 0 if
124 an error occurred (I/O error or invalid time format).
126 ASN1_TIME_diff() returns 1 for sucess and 0 for failure. It can fail if the
127 pass ASN1_TIME structure has invalid syntax for example.