ASN1_TIME_diff (3)

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NAME

ASN1_TIME_set, ASN1_TIME_adj, ASN1_TIME_check, ASN1_TIME_set_string, ASN1_TIME_print, ASN1_TIME_diff - ASN.1 Time functions.

SYNOPSIS

 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t);
 ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t,
                          int offset_day, long offset_sec);
 int ASN1_TIME_set_string(ASN1_TIME *s, const char *str);
 int ASN1_TIME_check(const ASN1_TIME *t);
 int ASN1_TIME_print(BIO *b, const ASN1_TIME *s);

 int ASN1_TIME_diff(int *pday, int *psec,
                    const ASN1_TIME *from, const ASN1_TIME *to);

DESCRIPTION

The function ASN1_TIME_set() sets the structure s to the time represented by the time_t value t. If s is a new structure is allocated and returned.

ASN1_TIME_adj() sets the

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 a new structure is allocated and returned.

ASN1_TIME_set_string() sets

structure s to the time represented by string str which must be in appropriate time format (for example or ).

ASN1_TIME_check() checks the syntax of

structure s.

ASN1_TIME_print() prints out the time s to

b in human readable format. It will be of the format [], for example ``Feb 3 00:55:52 2015 it does not include a newline. If the time structure has invalid format it prints out ``Bad time value'' and returns an error.

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 non-zero 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

the current time is used.

NOTES

The structure corresponds to the structure Time defined in et al. The time setting functions obey the rules outlined in if the date can be represented by UTCTime it is used, else GeneralizedTime is used.

The

structure is represented as an internally and can be freed up using ASN1_STRING_free().

The

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).

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.

BUGS

ASN1_TIME_print() currently does not print out the time zone: it either prints out `` or nothing. But all certificates complying with et al use anyway.

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");

RETURN VALUES

ASN1_TIME_set() and ASN1_TIME_adj() return a pointer to an structure or if an error occurred.

ASN1_TIME_set_string() returns 1 if the time value is successfully set and 0 otherwise.

ASN1_TIME_check() returns 1 if the structure is syntactically correct and 0 otherwise.

ASN1_TIME_print() returns 1 if the time is successfully printed out and 0 if an error occurred (I/O error or invalid time format).

ASN1_TIME_diff() returns 1 for sucess and 0 for failure. It can fail if the pass

structure has invalid syntax for example.