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Title "ASN1_TIME_SET 3"
way too many mistakes in technical documents.
The ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_adj() functions set the time 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 \s-1NULL\s0 a new structure is allocated and returned.
The ASN1_TIME_set_string(), ASN1_UTCTIME_set_string() and \fBASN1_GENERALIZEDTIME_set_string() functions set the time structure s to the time represented by string str which must be in appropriate \s-1ASN.1\s0 time format (for example \s-1YYMMDDHHMMSSZ\s0 or \s-1YYYYMMDDHHMMSSZ\s0). If s is \s-1NULL\s0 this function performs a format check on str only. The string str is copied into s.
\fBASN1_TIME_set_string_X509() sets \s-1ASN1_TIME\s0 structure s to the time represented by string str 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 s is \s-1NULL\s0 this function performs a format check on str only.
The ASN1_TIME_normalize() function converts an \s-1ASN1_GENERALIZEDTIME\s0 or \s-1ASN1_UTCTIME\s0 into a time value that can be used in a certificate. It should be used after the ASN1_TIME_set_string() functions and before \fBASN1_TIME_print() functions to get consistent (i.e. \s-1GMT\s0) results.
The ASN1_TIME_check(), ASN1_UTCTIME_check() and ASN1_GENERALIZEDTIME_check() functions check the syntax of the time structure s.
The ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() functions print the time structure s to \s-1BIO\s0 b 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 it 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.
\fBASN1_TIME_to_tm() converts the time s to the standard tm structure. If s is \s-1NULL,\s0 then the current time is converted. The output time is \s-1GMT.\s0 The tm_sec, tm_min, tm_hour, tm_mday, tm_wday, tm_yday, \fBtm_mon and tm_year fields of tm structure are set to proper values, whereas all other fields are set to 0. If tm is \s-1NULL\s0 this function performs a format check on s only. If s is in Generalized format with fractional seconds, e.g. \s-1YYYYMMDDHHMMSS.SSSZ,\s0 the fractional seconds will be lost while converting s to tm structure.
\fBASN1_TIME_diff() sets *pday and *psec to the time difference between \fBfrom 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 nonzero 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 \s-1NULL\s0 the current time is used.
The ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() functions compare the two times represented by the time structure s and the time_t t.
The ASN1_TIME_compare() function compares the two times represented by the time structures a and b.
The ASN1_TIME_to_generalizedtime() function converts an \s-1ASN1_TIME\s0 to an \s-1ASN1_GENERALIZEDTIME,\s0 regardless of year. If either out or \fB*out are \s-1NULL,\s0 then a new object is allocated and must be freed after use.
The \s-1ASN1_TIME, ASN1_UTCTIME\s0 and \s-1ASN1_GENERALIZEDTIME\s0 structures are represented as an \s-1ASN1_STRING\s0 internally and can be freed up using ASN1_STRING_free().
The \s-1ASN1_TIME\s0 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).
\s-1ASN1_UTCTIME\s0 is limited to a year range of 1950 through 2049.
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.
\fBASN1_TIME_adj() may change the type from \s-1ASN1_GENERALIZEDTIME\s0 to \s-1ASN1_UTCTIME,\s0 or vice versa, based on the resulting year. The ASN1_GENERALIZEDTIME_adj() and \fBASN1_UTCTIME_adj() functions will not modify the type of the return structure.
It is recommended that functions starting with \s-1ASN1_TIME\s0 be used instead of those starting with \s-1ASN1_UTCTIME\s0 or \s-1ASN1_GENERALIZEDTIME.\s0 The functions starting with \s-1ASN1_UTCTIME\s0 and \s-1ASN1_GENERALIZEDTIME\s0 act only on that specific time format. The functions starting with \s-1ASN1_TIME\s0 will operate on either format.
Use the ASN1_TIME_normalize() function to normalize the time value before printing to get \s-1GMT\s0 results.
\fBASN1_TIME_set_string(), ASN1_UTCTIME_set_string(), ASN1_GENERALIZEDTIME_set_string() \fBASN1_TIME_set_string_X509() return 1 if the time value is successfully set and 0 otherwise.
\fBASN1_TIME_normalize() returns 1 on success, and 0 on error.
\fBASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check() return 1 if the structure is syntactically correct and 0 otherwise.
\fBASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() return 1 if the time is successfully printed out and 0 if an error occurred (I/O error or invalid time format).
\fBASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if an error occurred (invalid time format).
\fBASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail if the passed-in time structure has invalid syntax, for example.
\fBASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if s is before t, 0 if s equals t, or 1 if s is after t. -2 is returned on error.
\fBASN1_TIME_compare() returns -1 if a is before b, 0 if a equals b, or 1 if a is after b. -2 is returned on error.
\fBASN1_TIME_to_generalizedtime() returns a pointer to the appropriate time structure on success or \s-1NULL\s0 if an error occurred.
.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
Determine if one time is later or sooner than the current time:
.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
Licensed under the OpenSSL license (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>.