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_TIME_print_ex, 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, 17ASN1_TIME_dup, ASN1_UTCTIME_dup, ASN1_GENERALIZEDTIME_dup - ASN.1 Time functions 18 19=head1 SYNOPSIS 20 21 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t); 22 ASN1_UTCTIME *ASN1_UTCTIME_set(ASN1_UTCTIME *s, time_t t); 23 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s, 24 time_t t); 25 26 ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t, int offset_day, 27 long offset_sec); 28 ASN1_UTCTIME *ASN1_UTCTIME_adj(ASN1_UTCTIME *s, time_t t, 29 int offset_day, long offset_sec); 30 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_adj(ASN1_GENERALIZEDTIME *s, 31 time_t t, int offset_day, 32 long offset_sec); 33 34 int ASN1_TIME_set_string(ASN1_TIME *s, const char *str); 35 int ASN1_TIME_set_string_X509(ASN1_TIME *s, const char *str); 36 int ASN1_UTCTIME_set_string(ASN1_UTCTIME *s, const char *str); 37 int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s, 38 const char *str); 39 40 int ASN1_TIME_normalize(ASN1_TIME *s); 41 42 int ASN1_TIME_check(const ASN1_TIME *t); 43 int ASN1_UTCTIME_check(const ASN1_UTCTIME *t); 44 int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *t); 45 46 int ASN1_TIME_print(BIO *b, const ASN1_TIME *s); 47 int ASN1_TIME_print_ex(BIO *bp, const ASN1_TIME *tm, unsigned long flags); 48 int ASN1_UTCTIME_print(BIO *b, const ASN1_UTCTIME *s); 49 int ASN1_GENERALIZEDTIME_print(BIO *b, const ASN1_GENERALIZEDTIME *s); 50 51 int ASN1_TIME_to_tm(const ASN1_TIME *s, struct tm *tm); 52 int ASN1_TIME_diff(int *pday, int *psec, const ASN1_TIME *from, 53 const ASN1_TIME *to); 54 55 int ASN1_TIME_cmp_time_t(const ASN1_TIME *s, time_t t); 56 int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t); 57 58 int ASN1_TIME_compare(const ASN1_TIME *a, const ASN1_TIME *b); 59 60 ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t, 61 ASN1_GENERALIZEDTIME **out); 62 63 ASN1_TIME *ASN1_TIME_dup(const ASN1_TIME *t); 64 ASN1_UTCTIME *ASN1_UTCTIME_dup(const ASN1_UTCTIME *t); 65 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_dup(const ASN1_GENERALIZEDTIME *t); 66 67=head1 DESCRIPTION 68 69The ASN1_TIME_set(), ASN1_UTCTIME_set() and ASN1_GENERALIZEDTIME_set() 70functions set the structure I<s> to the time represented by the time_t 71value I<t>. If I<s> is NULL a new time structure is allocated and returned. 72 73The ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_adj() 74functions set the time structure I<s> to the time represented 75by the time I<offset_day> and I<offset_sec> after the time_t value I<t>. 76The values of I<offset_day> or I<offset_sec> can be negative to set a 77time before I<t>. The I<offset_sec> value can also exceed the number of 78seconds in a day. If I<s> is NULL a new structure is allocated 79and returned. 80 81The ASN1_TIME_set_string(), ASN1_UTCTIME_set_string() and 82ASN1_GENERALIZEDTIME_set_string() functions set the time structure I<s> 83to the time represented by string I<str> which must be in appropriate ASN.1 84time format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ). If I<s> is NULL 85this function performs a format check on I<str> only. The string I<str> 86is copied into I<s>. 87 88ASN1_TIME_set_string_X509() sets B<ASN1_TIME> structure I<s> to the time 89represented by string I<str> which must be in appropriate time format 90that RFC 5280 requires, which means it only allows YYMMDDHHMMSSZ and 91YYYYMMDDHHMMSSZ (leap second is rejected), all other ASN.1 time format 92are not allowed. If I<s> is NULL this function performs a format check 93on I<str> only. 94 95The ASN1_TIME_normalize() function converts an B<ASN1_GENERALIZEDTIME> or 96B<ASN1_UTCTIME> into a time value that can be used in a certificate. It 97should be used after the ASN1_TIME_set_string() functions and before 98ASN1_TIME_print() functions to get consistent (i.e. GMT) results. 99 100The ASN1_TIME_check(), ASN1_UTCTIME_check() and ASN1_GENERALIZEDTIME_check() 101functions check the syntax of the time structure I<s>. 102 103The ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() 104functions print the time structure I<s> to BIO I<b> in human readable 105format. It will be of the format MMM DD HH:MM:SS YYYY [GMT], for example 106"Feb 3 00:55:52 2015 GMT", which does not include a newline. 107If the time structure has invalid format it prints out "Bad time value" and 108returns an error. The output for generalized time may include a fractional part 109following the second. 110 111ASN1_TIME_print_ex() provides I<flags> to specify the output format of the 112datetime. This can be either B<ASN1_DTFLGS_RFC822> or B<ASN1_DTFLGS_ISO8601>. 113 114ASN1_TIME_to_tm() converts the time I<s> to the standard I<tm> structure. 115If I<s> is NULL, then the current time is converted. The output time is GMT. 116The I<tm_sec>, I<tm_min>, I<tm_hour>, I<tm_mday>, I<tm_wday>, I<tm_yday>, 117I<tm_mon> and I<tm_year> fields of I<tm> structure are set to proper values, 118whereas all other fields are set to 0. If I<tm> is NULL this function performs 119a format check on I<s> only. If I<s> is in Generalized format with fractional 120seconds, e.g. YYYYMMDDHHMMSS.SSSZ, the fractional seconds will be lost while 121converting I<s> to I<tm> structure. 122 123ASN1_TIME_diff() sets I<*pday> and I<*psec> to the time difference between 124I<from> and I<to>. If I<to> represents a time later than I<from> then 125one or both (depending on the time difference) of I<*pday> and I<*psec> 126will be positive. If I<to> represents a time earlier than I<from> then 127one or both of I<*pday> and I<*psec> will be negative. If I<to> and I<from> 128represent the same time then I<*pday> and I<*psec> will both be zero. 129If both I<*pday> and I<*psec> are nonzero they will always have the same 130sign. The value of I<*psec> will always be less than the number of seconds 131in a day. If I<from> or I<to> is NULL the current time is used. 132 133The ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() functions compare 134the two times represented by the time structure I<s> and the time_t I<t>. 135 136The ASN1_TIME_compare() function compares the two times represented by the 137time structures I<a> and I<b>. 138 139The ASN1_TIME_to_generalizedtime() function converts an B<ASN1_TIME> to an 140B<ASN1_GENERALIZEDTIME>, regardless of year. If either I<out> or 141I<*out> are NULL, then a new object is allocated and must be freed after use. 142 143The ASN1_TIME_dup(), ASN1_UTCTIME_dup() and ASN1_GENERALIZEDTIME_dup() functions 144duplicate the time structure I<t> and return the duplicated result 145correspondingly. 146 147=head1 NOTES 148 149The B<ASN1_TIME> structure corresponds to the ASN.1 structure B<Time> 150defined in RFC5280 et al. The time setting functions obey the rules outlined 151in RFC5280: if the date can be represented by UTCTime it is used, else 152GeneralizedTime is used. 153 154The B<ASN1_TIME>, B<ASN1_UTCTIME> and B<ASN1_GENERALIZEDTIME> structures are 155represented as an B<ASN1_STRING> internally and can be freed up using 156ASN1_STRING_free(). 157 158The B<ASN1_TIME> structure can represent years from 0000 to 9999 but no attempt 159is made to correct ancient calendar changes (for example from Julian to 160Gregorian calendars). 161 162B<ASN1_UTCTIME> is limited to a year range of 1950 through 2049. 163 164Some applications add offset times directly to a time_t value and pass the 165results to ASN1_TIME_set() (or equivalent). This can cause problems as the 166time_t value can overflow on some systems resulting in unexpected results. 167New applications should use ASN1_TIME_adj() instead and pass the offset value 168in the I<offset_sec> and I<offset_day> parameters instead of directly 169manipulating a time_t value. 170 171ASN1_TIME_adj() may change the type from B<ASN1_GENERALIZEDTIME> to 172B<ASN1_UTCTIME>, or vice versa, based on the resulting year. 173ASN1_GENERALIZEDTIME_adj() and ASN1_UTCTIME_adj() will not modify the type 174of the return structure. 175 176It is recommended that functions starting with B<ASN1_TIME> be used instead of 177those starting with B<ASN1_UTCTIME> or B<ASN1_GENERALIZEDTIME>. The functions 178starting with B<ASN1_UTCTIME> and B<ASN1_GENERALIZEDTIME> act only on that 179specific time format. The functions starting with B<ASN1_TIME> will operate on 180either format. 181 182=head1 BUGS 183 184ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() do 185not print out the timezone: it either prints out "GMT" or nothing. But all 186certificates complying with RFC5280 et al use GMT anyway. 187 188ASN1_TIME_print(), ASN1_TIME_print_ex(), ASN1_UTCTIME_print() and 189ASN1_GENERALIZEDTIME_print() do not distinguish if they fail because 190of an I/O error or invalid time format. 191 192Use the ASN1_TIME_normalize() function to normalize the time value before 193printing to get GMT results. 194 195=head1 RETURN VALUES 196 197ASN1_TIME_set(), ASN1_UTCTIME_set(), ASN1_GENERALIZEDTIME_set(), 198ASN1_TIME_adj(), ASN1_UTCTIME_adj() and ASN1_GENERALIZEDTIME_set() return 199a pointer to a time structure or NULL if an error occurred. 200 201ASN1_TIME_set_string(), ASN1_UTCTIME_set_string(), 202ASN1_GENERALIZEDTIME_set_string() and ASN1_TIME_set_string_X509() return 2031 if the time value is successfully set and 0 otherwise. 204 205ASN1_TIME_normalize() returns 1 on success, and 0 on error. 206 207ASN1_TIME_check(), ASN1_UTCTIME_check and ASN1_GENERALIZEDTIME_check() return 1 208if the structure is syntactically correct and 0 otherwise. 209 210ASN1_TIME_print(), ASN1_UTCTIME_print() and ASN1_GENERALIZEDTIME_print() 211return 1 if the time is successfully printed out and 2120 if an I/O error occurred an error occurred (I/O error or invalid time format). 213 214ASN1_TIME_to_tm() returns 1 if the time is successfully parsed and 0 if an 215error occurred (invalid time format). 216 217ASN1_TIME_diff() returns 1 for success and 0 for failure. It can fail if the 218passed-in time structure has invalid syntax, for example. 219 220ASN1_TIME_cmp_time_t() and ASN1_UTCTIME_cmp_time_t() return -1 if I<s> is 221before I<t>, 0 if I<s> equals I<t>, or 1 if I<s> is after I<t>. -2 is returned 222on error. 223 224ASN1_TIME_compare() returns -1 if I<a> is before I<b>, 0 if I<a> equals I<b>, 225or 1 if I<a> is after I<b>. -2 is returned on error. 226 227ASN1_TIME_to_generalizedtime() returns a pointer to the appropriate time 228structure on success or NULL if an error occurred. 229 230ASN1_TIME_dup(), ASN1_UTCTIME_dup() and ASN1_GENERALIZEDTIME_dup() return a 231pointer to a time structure or NULL if an error occurred. 232 233=head1 EXAMPLES 234 235Set a time structure to one hour after the current time and print it out: 236 237 #include <time.h> 238 #include <openssl/asn1.h> 239 240 ASN1_TIME *tm; 241 time_t t; 242 BIO *b; 243 244 t = time(NULL); 245 tm = ASN1_TIME_adj(NULL, t, 0, 60 * 60); 246 b = BIO_new_fp(stdout, BIO_NOCLOSE); 247 ASN1_TIME_print(b, tm); 248 ASN1_STRING_free(tm); 249 BIO_free(b); 250 251Determine if one time is later or sooner than the current time: 252 253 int day, sec; 254 255 if (!ASN1_TIME_diff(&day, &sec, NULL, to)) 256 /* Invalid time format */ 257 258 if (day > 0 || sec > 0) 259 printf("Later\n"); 260 else if (day < 0 || sec < 0) 261 printf("Sooner\n"); 262 else 263 printf("Same\n"); 264 265=head1 HISTORY 266 267The ASN1_TIME_to_tm() function was added in OpenSSL 1.1.1. 268The ASN1_TIME_set_string_X509() function was added in OpenSSL 1.1.1. 269The ASN1_TIME_normalize() function was added in OpenSSL 1.1.1. 270The ASN1_TIME_cmp_time_t() function was added in OpenSSL 1.1.1. 271The ASN1_TIME_compare() function was added in OpenSSL 1.1.1. 272 273=head1 COPYRIGHT 274 275Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved. 276 277Licensed under the Apache License 2.0 (the "License"). You may not use 278this file except in compliance with the License. You can obtain a copy 279in the file LICENSE in the source distribution or at 280L<https://www.openssl.org/source/license.html>. 281 282=cut 283