ASN1_TIME_set(3)                    OpenSSL                   ASN1_TIME_set(3)



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

SSYYNNOOPPSSIISS
        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);

DDEESSCCRRIIPPTTIIOONN
       The function _A_S_N_1___T_I_M_E___s_e_t_(_) sets the ASN1_TIME structure ss to the time
       represented by the time_t value tt. If ss is NULL a new ASN1_TIME struc-
       ture is allocated and returned.

       _A_S_N_1___T_I_M_E___a_d_j_(_) sets the ASN1_TIME structure ss to the time represented
       by the time ooffffsseett__ddaayy and ooffffsseett__sseecc after the time_t value tt.  The
       values of ooffffsseett__ddaayy or ooffffsseett__sseecc can be negative to set a time before
       tt. The ooffffsseett__sseecc value can also exceed the number of seconds in a day.
       If ss is NULL a new ASN1_TIME structure is allocated and returned.

       _A_S_N_1___T_I_M_E___s_e_t___s_t_r_i_n_g_(_) sets ASN1_TIME structure ss to the time repre-
       sented by string ssttrr which must be in appropriate ASN.1 time format
       (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ).

       _A_S_N_1___T_I_M_E___c_h_e_c_k_(_) checks the syntax of ASN1_TIME structure ss.

       _A_S_N_1___T_I_M_E___p_r_i_n_t_(_) prints out the time ss to BIO bb in human readable for-
       mat. 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.

       _A_S_N_1___T_I_M_E___d_i_f_f_(_) sets **ppddaayy and **ppsseecc to the time difference between
       ffrroomm and ttoo. If ttoo represents a time later than ffrroomm then one or both
       (depending on the time difference) of **ppddaayy and **ppsseecc will be positive.
       If ttoo represents a time earlier than ffrroomm then one or both of **ppddaayy and
       **ppsseecc will be negative. If ttoo and ffrroomm represent the same time then
       **ppddaayy and **ppsseecc will both be zero.  If both **ppddaayy and **ppsseecc are non-
       zero they will always have the same sign. The value of **ppsseecc will
       always be less than the number of seconds in a day. If ffrroomm or ttoo is
       NULL the current time is used.

NNOOTTEESS
       The ASN1_TIME structure corresponds to the ASN.1 structure TTiimmee 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 structure is represented as an ASN1_STRING internally and
       can be freed up using _A_S_N_1___S_T_R_I_N_G___f_r_e_e_(_).

       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).

       Some applications add offset times directly to a time_t value and pass
       the results to _A_S_N_1___T_I_M_E___s_e_t_(_) (or equivalent). This can cause problems
       as the time_t value can overflow on some systems resulting in unex-
       pected results.  New applications should use _A_S_N_1___T_I_M_E___a_d_j_(_) instead
       and pass the offset value in the ooffffsseett__sseecc and ooffffsseett__ddaayy parameters
       instead of directly manipulating a time_t value.

BBUUGGSS
       _A_S_N_1___T_I_M_E___p_r_i_n_t_(_) currently does not print out the time zone: it either
       prints out "GMT" or nothing. But all certificates complying with
       RFC5280 et al use GMT anyway.

EEXXAAMMPPLLEESS
       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");

RREETTUURRNN VVAALLUUEESS
       _A_S_N_1___T_I_M_E___s_e_t_(_) and _A_S_N_1___T_I_M_E___a_d_j_(_) return a pointer to an ASN1_TIME
       structure or NULL if an error occurred.

       _A_S_N_1___T_I_M_E___s_e_t___s_t_r_i_n_g_(_) returns 1 if the time value is successfully set
       and 0 otherwise.

       _A_S_N_1___T_I_M_E___c_h_e_c_k_(_) returns 1 if the structure is syntactically correct
       and 0 otherwise.

       _A_S_N_1___T_I_M_E___p_r_i_n_t_(_) returns 1 if the time is successfully printed out and
       0 if an error occurred (I/O error or invalid time format).

       _A_S_N_1___T_I_M_E___d_i_f_f_(_) returns 1 for sucess and 0 for failure. It can fail if
       the pass ASN1_TIME structure has invalid syntax for example.



1.0.2u                            2019-12-20                  ASN1_TIME_set(3)