1=pod 2 3=head1 NAME 4 5ASN1_TIME_set, ASN1_TIME_adj, ASN1_TIME_check, ASN1_TIME_set_string, 6ASN1_TIME_print, ASN1_TIME_diff - ASN.1 Time functions. 7 8=head1 SYNOPSIS 9 10 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t); 11 ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, time_t t, 12 int offset_day, long offset_sec); 13 int ASN1_TIME_set_string(ASN1_TIME *s, const char *str); 14 int ASN1_TIME_check(const ASN1_TIME *t); 15 int ASN1_TIME_print(BIO *b, const ASN1_TIME *s); 16 17 int ASN1_TIME_diff(int *pday, int *psec, 18 const ASN1_TIME *from, const ASN1_TIME *to); 19 20=head1 DESCRIPTION 21 22The function ASN1_TIME_set() sets the ASN1_TIME structure B<s> to the 23time represented by the time_t value B<t>. If B<s> is NULL a new ASN1_TIME 24structure is allocated and returned. 25 26ASN1_TIME_adj() sets the ASN1_TIME structure B<s> to the time represented 27by the time B<offset_day> and B<offset_sec> after the time_t value B<t>. 28The values of B<offset_day> or B<offset_sec> can be negative to set a 29time before B<t>. The B<offset_sec> value can also exceed the number of 30seconds in a day. If B<s> is NULL a new ASN1_TIME structure is allocated 31and returned. 32 33ASN1_TIME_set_string() sets ASN1_TIME structure B<s> to the time 34represented by string B<str> which must be in appropriate ASN.1 time 35format (for example YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ). 36 37ASN1_TIME_check() checks the syntax of ASN1_TIME structure B<s>. 38 39ASN1_TIME_print() prints out the time B<s> to BIO B<b> in human readable 40format. It will be of the format MMM DD HH:MM:SS YYYY [GMT], for example 41"Feb 3 00:55:52 2015 GMT" it does not include a newline. If the time 42structure has invalid format it prints out "Bad time value" and returns 43an error. 44 45ASN1_TIME_diff() sets B<*pday> and B<*psec> to the time difference between 46B<from> and B<to>. If B<to> represents a time later than B<from> then 47one or both (depending on the time difference) of B<*pday> and B<*psec> 48will be positive. If B<to> represents a time earlier than B<from> then 49one or both of B<*pday> and B<*psec> will be negative. If B<to> and B<from> 50represent the same time then B<*pday> and B<*psec> will both be zero. 51If both B<*pday> and B<*psec> are non-zero they will always have the same 52sign. The value of B<*psec> will always be less than the number of seconds 53in a day. If B<from> or B<to> is NULL the current time is used. 54 55=head1 NOTES 56 57The ASN1_TIME structure corresponds to the ASN.1 structure B<Time> 58defined in RFC5280 et al. The time setting functions obey the rules outlined 59in RFC5280: if the date can be represented by UTCTime it is used, else 60GeneralizedTime is used. 61 62The ASN1_TIME structure is represented as an ASN1_STRING internally and can 63be freed up using ASN1_STRING_free(). 64 65The ASN1_TIME structure can represent years from 0000 to 9999 but no attempt 66is made to correct ancient calendar changes (for example from Julian to 67Gregorian calendars). 68 69Some applications add offset times directly to a time_t value and pass the 70results to ASN1_TIME_set() (or equivalent). This can cause problems as the 71time_t value can overflow on some systems resulting in unexpected results. 72New applications should use ASN1_TIME_adj() instead and pass the offset value 73in the B<offset_sec> and B<offset_day> parameters instead of directly 74manipulating a time_t value. 75 76=head1 BUGS 77 78ASN1_TIME_print() currently does not print out the time zone: it either prints 79out "GMT" or nothing. But all certificates complying with RFC5280 et al use GMT 80anyway. 81 82=head1 EXAMPLES 83 84Set a time structure to one hour after the current time and print it out: 85 86 #include <time.h> 87 #include <openssl/asn1.h> 88 ASN1_TIME *tm; 89 time_t t; 90 BIO *b; 91 t = time(NULL); 92 tm = ASN1_TIME_adj(NULL, t, 0, 60 * 60); 93 b = BIO_new_fp(stdout, BIO_NOCLOSE); 94 ASN1_TIME_print(b, tm); 95 ASN1_STRING_free(tm); 96 BIO_free(b); 97 98Determine if one time is later or sooner than the current time: 99 100 int day, sec; 101 102 if (!ASN1_TIME_diff(&day, &sec, NULL, to)) 103 /* Invalid time format */ 104 105 if (day > 0 || sec > 0) 106 printf("Later\n"); 107 else if (day < 0 || sec < 0) 108 printf("Sooner\n"); 109 else 110 printf("Same\n"); 111 112=head1 RETURN VALUES 113 114ASN1_TIME_set() and ASN1_TIME_adj() return a pointer to an ASN1_TIME structure 115or NULL if an error occurred. 116 117ASN1_TIME_set_string() returns 1 if the time value is successfully set and 1180 otherwise. 119 120ASN1_TIME_check() returns 1 if the structure is syntactically correct and 0 121otherwise. 122 123ASN1_TIME_print() returns 1 if the time is successfully printed out and 0 if 124an error occurred (I/O error or invalid time format). 125 126ASN1_TIME_diff() returns 1 for sucess and 0 for failure. It can fail if the 127pass ASN1_TIME structure has invalid syntax for example. 128 129=cut 130