1=pod 2 3=head1 NAME 4 5ASN1_TIME_set, ASN1_UTCTIME_set, ASN1_GENERALIZEDTIME_set, 6ASN1_TIME_adj, ASN1_UTCTIME_adj, ASN1_GENERALIZEDTIME_adj, 7ASN1_TIME_check, ASN1_UTCTIME_check, ASN1_GENERALIZEDTIME_check, 8ASN1_TIME_set_string, ASN1_UTCTIME_set_string, ASN1_GENERALIZEDTIME_set_string, 9ASN1_TIME_set_string_X509, 10ASN1_TIME_normalize, 11ASN1_TIME_to_tm, 12ASN1_TIME_print, ASN1_UTCTIME_print, ASN1_GENERALIZEDTIME_print, 13ASN1_TIME_diff, 14ASN1_TIME_cmp_time_t, ASN1_UTCTIME_cmp_time_t, 15ASN1_TIME_compare, 16ASN1_TIME_to_generalizedtime - ASN.1 Time functions 17 18=head1 SYNOPSIS 19 20 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t); 21 ASN1_UTCTIME *ASN1_UTCTIME_set(ASN1_UTCTIME *s, time_t t); 22 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s, 23 time_t t); 24 25 ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t, int offset_day, 26 long offset_sec); 27 ASN1_UTCTIME *ASN1_UTCTIME_adj(ASN1_UTCTIME *s, time_t t, 28 int offset_day, long offset_sec); 29 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_adj(ASN1_GENERALIZEDTIME *s, 30 time_t t, int offset_day, 31 long offset_sec); 32 33 int ASN1_TIME_set_string(ASN1_TIME *s, const char *str); 34 int ASN1_TIME_set_string_X509(ASN1_TIME *s, const char *str); 35 int ASN1_UTCTIME_set_string(ASN1_UTCTIME *s, const char *str); 36 int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s, 37 const char *str); 38 39 int ASN1_TIME_normalize(ASN1_TIME *s); 40 41 int ASN1_TIME_check(const ASN1_TIME *t); 42 int ASN1_UTCTIME_check(const ASN1_UTCTIME *t); 43 int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *t); 44 45 int ASN1_TIME_print(BIO *b, const ASN1_TIME *s); 46 int ASN1_UTCTIME_print(BIO *b, const ASN1_UTCTIME *s); 47 int ASN1_GENERALIZEDTIME_print(BIO *b, const ASN1_GENERALIZEDTIME *s); 48 49 int ASN1_TIME_to_tm(const ASN1_TIME *s, struct tm *tm); 50 int ASN1_TIME_diff(int *pday, int *psec, const ASN1_TIME *from, 51 const ASN1_TIME *to); 52 53 int ASN1_TIME_cmp_time_t(const ASN1_TIME *s, time_t t); 54 int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t); 55 56 int ASN1_TIME_compare(const ASN1_TIME *a, const ASN1_TIME *b); 57 58 ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t, 59 ASN1_GENERALIZEDTIME **out); 60 61=head1 DESCRIPTION 62 63The ASN1_TIME_set(), ASN1_UTCTIME_set() and ASN1_GENERALIZEDTIME_set() 64functions set the structure B<s> to the time represented by the time_t 65value B<t>. If B<s> is NULL a new time structure is allocated and returned. 66 67The ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_adj() 68functions set the time structure B<s> to the time represented 69by the time B<offset_day> and B<offset_sec> after the time_t value B<t>. 70The values of B<offset_day> or B<offset_sec> can be negative to set a 71time before B<t>. The B<offset_sec> value can also exceed the number of 72seconds in a day. If B<s> is NULL a new structure is allocated 73and returned. 74 75The ASN1_TIME_set_string(), ASN1_UTCTIME_set_string() and 76ASN1_GENERALIZEDTIME_set_string() functions set the time structure B<s> 77to the time represented by string B<str> which must be in appropriate ASN.1 78time format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ). If B<s> is NULL 79this function performs a format check on B<str> only. The string B<str> 80is copied into B<s>. 81 82ASN1_TIME_set_string_X509() sets ASN1_TIME structure B<s> to the time 83represented by string B<str> which must be in appropriate time format 84that RFC 5280 requires, which means it only allows YYMMDDHHMMSSZ and 85YYYYMMDDHHMMSSZ (leap second is rejected), all other ASN.1 time format 86are not allowed. If B<s> is NULL this function performs a format check 87on B<str> only. 88 89The ASN1_TIME_normalize() function converts an ASN1_GENERALIZEDTIME or 90ASN1_UTCTIME into a time value that can be used in a certificate. It 91should be used after the ASN1_TIME_set_string() functions and before 92ASN1_TIME_print() functions to get consistent (i.e. GMT) results. 93 94The ASN1_TIME_check(), ASN1_UTCTIME_check() and ASN1_GENERALIZEDTIME_check() 95functions check the syntax of the time structure B<s>. 96 97The ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() 98functions print the time structure B<s> to BIO B<b> in human readable 99format. It will be of the format MMM DD HH:MM:SS YYYY [GMT], for example 100"Feb 3 00:55:52 2015 GMT" it does not include a newline. If the time 101structure has invalid format it prints out "Bad time value" and returns 102an error. The output for generalized time may include a fractional part 103following the second. 104 105ASN1_TIME_to_tm() converts the time B<s> to the standard B<tm> structure. 106If B<s> is NULL, then the current time is converted. The output time is GMT. 107The B<tm_sec>, B<tm_min>, B<tm_hour>, B<tm_mday>, B<tm_wday>, B<tm_yday>, 108B<tm_mon> and B<tm_year> fields of B<tm> structure are set to proper values, 109whereas all other fields are set to 0. If B<tm> is NULL this function performs 110a format check on B<s> only. If B<s> is in Generalized format with fractional 111seconds, e.g. YYYYMMDDHHMMSS.SSSZ, the fractional seconds will be lost while 112converting B<s> to B<tm> structure. 113 114ASN1_TIME_diff() sets B<*pday> and B<*psec> to the time difference between 115B<from> and B<to>. If B<to> represents a time later than B<from> then 116one or both (depending on the time difference) of B<*pday> and B<*psec> 117will be positive. If B<to> represents a time earlier than B<from> then 118one or both of B<*pday> and B<*psec> will be negative. If B<to> and B<from> 119represent the same time then B<*pday> and B<*psec> will both be zero. 120If both B<*pday> and B<*psec> are nonzero they will always have the same 121sign. The value of B<*psec> will always be less than the number of seconds 122in a day. If B<from> or B<to> is NULL the current time is used. 123 124The ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() functions compare 125the two times represented by the time structure B<s> and the time_t B<t>. 126 127The ASN1_TIME_compare() function compares the two times represented by the 128time structures B<a> and B<b>. 129 130The ASN1_TIME_to_generalizedtime() function converts an ASN1_TIME to an 131ASN1_GENERALIZEDTIME, regardless of year. If either B<out> or 132B<*out> are NULL, then a new object is allocated and must be freed after use. 133 134=head1 NOTES 135 136The ASN1_TIME structure corresponds to the ASN.1 structure B<Time> 137defined in RFC5280 et al. The time setting functions obey the rules outlined 138in RFC5280: if the date can be represented by UTCTime it is used, else 139GeneralizedTime is used. 140 141The ASN1_TIME, ASN1_UTCTIME and ASN1_GENERALIZEDTIME structures are represented 142as an ASN1_STRING internally and can be freed up using ASN1_STRING_free(). 143 144The ASN1_TIME structure can represent years from 0000 to 9999 but no attempt 145is made to correct ancient calendar changes (for example from Julian to 146Gregorian calendars). 147 148ASN1_UTCTIME is limited to a year range of 1950 through 2049. 149 150Some applications add offset times directly to a time_t value and pass the 151results to ASN1_TIME_set() (or equivalent). This can cause problems as the 152time_t value can overflow on some systems resulting in unexpected results. 153New applications should use ASN1_TIME_adj() instead and pass the offset value 154in the B<offset_sec> and B<offset_day> parameters instead of directly 155manipulating a time_t value. 156 157ASN1_TIME_adj() may change the type from ASN1_GENERALIZEDTIME to ASN1_UTCTIME, 158or vice versa, based on the resulting year. The ASN1_GENERALIZEDTIME_adj() and 159ASN1_UTCTIME_adj() functions will not modify the type of the return structure. 160 161It is recommended that functions starting with ASN1_TIME be used instead of 162those starting with ASN1_UTCTIME or ASN1_GENERALIZEDTIME. The functions 163starting with ASN1_UTCTIME and ASN1_GENERALIZEDTIME act only on that specific 164time format. The functions starting with ASN1_TIME will operate on either 165format. 166 167=head1 BUGS 168 169ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() 170do not print out the timezone: it either prints out "GMT" or nothing. But all 171certificates complying with RFC5280 et al use GMT anyway. 172 173Use the ASN1_TIME_normalize() function to normalize the time value before 174printing to get GMT results. 175 176=head1 RETURN VALUES 177 178ASN1_TIME_set(), ASN1_UTCTIME_set(), ASN1_GENERALIZEDTIME_set(), ASN1_TIME_adj(), 179ASN1_UTCTIME_adj and ASN1_GENERALIZEDTIME_set return a pointer to a time structure 180or NULL if an error occurred. 181 182ASN1_TIME_set_string(), ASN1_UTCTIME_set_string(), ASN1_GENERALIZEDTIME_set_string() 183ASN1_TIME_set_string_X509() return 1 if the time value is successfully set and 0 otherwise. 184 185ASN1_TIME_normalize() returns 1 on success, and 0 on error. 186 187ASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check() return 1 188if the structure is syntactically correct and 0 otherwise. 189 190ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() return 1 191if the time is successfully printed out and 0 if an error occurred (I/O error or 192invalid time format). 193 194ASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if an 195error occurred (invalid time format). 196 197ASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail if the 198passed-in time structure has invalid syntax, for example. 199 200ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if B<s> is 201before B<t>, 0 if B<s> equals B<t>, or 1 if B<s> is after B<t>. -2 is returned 202on error. 203 204ASN1_TIME_compare() returns -1 if B<a> is before B<b>, 0 if B<a> equals B<b>, or 1 if B<a> is after B<b>. -2 is returned on error. 205 206ASN1_TIME_to_generalizedtime() returns a pointer to 207the appropriate time structure on success or NULL if an error occurred. 208 209=head1 EXAMPLES 210 211Set a time structure to one hour after the current time and print it 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 227Determine 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"); 240 241=head1 HISTORY 242 243The ASN1_TIME_to_tm() function was added in OpenSSL 1.1.1. 244The ASN1_TIME_set_string_X509() function was added in OpenSSL 1.1.1. 245The ASN1_TIME_normalize() function was added in OpenSSL 1.1.1. 246The ASN1_TIME_cmp_time_t() function was added in OpenSSL 1.1.1. 247The ASN1_TIME_compare() function was added in OpenSSL 1.1.1. 248 249=head1 COPYRIGHT 250 251Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved. 252 253Licensed under the OpenSSL license (the "License"). You may not use 254this file except in compliance with the License. You can obtain a copy 255in the file LICENSE in the source distribution or at 256L<https://www.openssl.org/source/license.html>. 257 258=cut 259