Openssl 代码中提供了函数 ASN1_TIME_set ，把 time_t 格式的时间转化为 ASN1_TIME
函数原型为
ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t)
但是没有找到类似 ASN1_TIME_get 函数，把 ASN1_TIME 转化为 time_t
下面是一个ASN1_TIME_get 测试可用
int mypint( const char ** s, int n, int min, int max, int * e)
{
int retval = 0;
while (n) {
if (**s < '0' || **s > '9') { *e = 1; return 0; }
retval *= 10;
retval += **s - '0';
--n; ++(*s);
}
if (retval < min || retval > max) *e = 1;
return retval;
}
time_t ASN1_TIME_get ( ASN1_TIME * a, int *err)
{
char days[2][12] ={{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }};
int dummy;
const char *s;
int generalized;
struct tm t;
int i, year, isleap, offset;
time_t retval;
if (err == NULL)
err = &dummy;
if (a->type == V_ASN1_GENERALIZEDTIME) {
generalized = 1;
} else if (a->type == V_ASN1_UTCTIME) {
generalized = 0;
} else {
*err = 1;
return 0;
}
s = (char *)a->data; // Data should be always null terminated
if (s == NULL || s[a->length] != '\0') {
*err = 1;
return 0;
}
*err = 0;
if (generalized) {
t.tm_year = mypint(&s, 4, 0, 9999, err) - 1900;
} else {
t.tm_year = mypint(&s, 2, 0, 99, err);
if (t.tm_year < 50)
t.tm_year += 100;
}
t.tm_mon = mypint(&s, 2, 1, 12, err) - 1;
t.tm_mday = mypint(&s, 2, 1, 31, err);
// NOTE: It's not yet clear, if this implementation is 100% correct
// for GeneralizedTime... but at least misinterpretation is
// impossible --- we just throw an exception
t.tm_hour = mypint(&s, 2, 0, 23, err);
t.tm_min = mypint(&s, 2, 0, 59, err);
if (*s >= '0' && *s <= '9') {
t.tm_sec = mypint(&s, 2, 0, 59, err);
} else {
t.tm_sec = 0;
}
if (*err)
return 0; // Format violation
if (generalized) {
// skip fractional seconds if any
while (*s == '.' || *s == ',' || (*s >= '0' && *s <= '9')) ++s;
// special treatment for local time
if (*s == 0) {
t.tm_isdst = -1;
retval = mktime(&t); // Local time is easy :)
if (retval == (time_t)-1) {
*err = 2;
retval = 0;
}
return retval;
}
}
if (*s == 'Z') {
offset = 0;
++s;
} else if (*s == '-' || *s == '+') {
i = (*s++ == '-');
offset = mypint(&s, 2, 0, 12, err);
offset *= 60;
offset += mypint(&s, 2, 0, 59, err);
if (*err) return 0; // Format violation
if (i) offset = -offset;
} else {
*err = 1;
return 0;
}
if (*s) {
*err = 1;
return 0;
}
// And here comes the hard part --- there's no standard function to
// convert struct tm containing UTC time into time_t without
// messing global timezone settings (breaks multithreading and may
// cause other problems) and thus we have to do this "by hand"
//
// NOTE: Overflow check does not detect too big overflows, but is
// sufficient thanks to the fact that year numbers are limited to four
// digit non-negative values.
retval = t.tm_sec;
retval += (t.tm_min - offset) * 60;
retval += t.tm_hour * 3600;
retval += (t.tm_mday - 1) * 86400;
year = t.tm_year + 1900;
if ( sizeof (time_t) == 4) {
// This is just to avoid too big overflows being undetected, finer
// overflow detection is done below.
if (year < 1900 || year > 2040) *err = 2;
}
// FIXME: Does POSIX really say, that all years divisible by 4 are
// leap years (for consistency)??? Fortunately, this problem does
// not exist for 32-bit time_t and we should'nt be worried about
// this until the year of 2100 :)
isleap = ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
for (i = t.tm_mon - 1; i >= 0; --i) retval += days[isleap][i] * 86400;
retval += (year - 1970) * 31536000;
if (year < 1970) {
retval -= ((1970 - year + 2) / 4) * 86400;
if ( sizeof (time_t) > 4) {
for (i = 1900; i >= year; i -= 100) {
if (i % 400 == 0) continue ;
retval += 86400;
}
}
if (retval >= 0) *err = 2;
} else {
retval += ((year - 1970 + 1) / 4) * 86400;
if ( sizeof (time_t) > 4) {
for (i = 2100; i < year; i += 100) {
// The following condition is the reason to
// start with 2100 instead of 2000
if (i % 400 == 0) continue ;
retval -= 86400;
}
}
if (retval < 0) *err = 2;
}
if (*err) retval = 0;
return retval;
}头文件大概需要这些：
#include <time.h>
#include <stdlib.h>
#include <openssl/pem.h>
#include <openssl/conf.h>
#include <openssl/x509v3.h>
2） %d-%d-%d %d:%d:%d 格式时间转unix时间戳
time_t strTime2unix(string& timeStamp)
{
struct tm tm;
memset(&tm, 0, sizeof(tm));
sscanf(timeStamp.c_str(), "%d-%d-%d %d:%d:%d",
&tm.tm_year, &tm.tm_mon, &tm.tm_mday,
&tm.tm_hour, &tm.tm_min, &tm.tm_sec);
tm.tm_year -= 1900;
tm.tm_mon--;
return mktime(&tm);
}参考链接：
http://blog.csdn.net/nanhaizhixin/article/details/8349668
http://www.eefocus.com/xuefu2009/blog/10-03/187348_f456a.html