Modify time handling so X509 is not affected by 2038 issues

src/lib/asn1/asn1_time.cpp

@@ -250,8 +250,7 @@ std::chrono::system_clock::time_point ASN1_Time::to_std_timepoint() const {
 }
 
 uint64_t ASN1_Time::time_since_epoch() const {
-   auto tp = this->to_std_timepoint();
-   return std::chrono::duration_cast<std::chrono::seconds>(tp.time_since_epoch()).count();
+   return calendar_point(m_year, m_month, m_day, m_hour, m_minute, m_second).seconds_since_epoch();
 }
 
 /*

src/lib/utils/calendar.cpp

@@ -8,6 +8,7 @@
 
 #include <botan/internal/calendar.h>
 
+#include <botan/assert.h>
 #include <botan/exceptn.h>
 #include <ctime>
 #include <iomanip>
@@ -43,7 +44,9 @@ See https://howardhinnant.github.io/date_algorithms.html#days_from_civil
 for details and explaination. The code is slightly simplified by our assumption
 that the date is at least 1970, which is sufficient for our purposes.
 */
-size_t days_since_epoch(uint32_t year, uint32_t month, uint32_t day) {
+uint64_t days_since_epoch(uint32_t year, uint32_t month, uint32_t day) {
+   BOTAN_ARG_CHECK(year >= 1970, "Years before 1970 not supported");
+
    if(month <= 2) {
       year -= 1;
    }
@@ -56,29 +59,12 @@ size_t days_since_epoch(uint32_t year, uint32_t month, uint32_t day) {
 
 }  // namespace
 
-std::chrono::system_clock::time_point calendar_point::to_std_timepoint() const {
-   if(year() < 1970) {
-      throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years before 1970");
-   }
-
-   // 32 bit time_t ends at January 19, 2038
-   // https://msdn.microsoft.com/en-us/library/2093ets1.aspx
-   // Throw after 2037 if 32 bit time_t is used
-
-   if constexpr(sizeof(std::time_t) == 4) {
-      if(year() > 2037) {
-         throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years after 2037 on this system");
-      }
-   }
-
-   // This upper bound is completely arbitrary
-   if(year() >= 2400) {
-      throw Invalid_Argument("calendar_point::to_std_timepoint() does not support years after 2400");
-   }
-
-   const uint64_t seconds_64 =
-      (days_since_epoch(year(), month(), day()) * 86400) + (hour() * 60 * 60) + (minutes() * 60) + seconds();
+uint64_t calendar_point::seconds_since_epoch() const {
+   return (days_since_epoch(year(), month(), day()) * 86400) + (hour() * 60 * 60) + (minutes() * 60) + seconds();
+}
 
+std::chrono::system_clock::time_point calendar_point::to_std_timepoint() const {
+   const uint64_t seconds_64 = this->seconds_since_epoch();
    const time_t seconds_time_t = static_cast<time_t>(seconds_64);
 
    if(seconds_64 - seconds_time_t != 0) {

src/lib/utils/calendar.h

@@ -58,8 +58,16 @@ class BOTAN_TEST_API calendar_point {
       */
       calendar_point(const std::chrono::system_clock::time_point& time_point);
 
+      /**
+      * Return seconds since epoch
+      */
+      uint64_t seconds_since_epoch() const;
+
       /**
       * Returns an STL timepoint object
+      *
+      * Note this throws an exception if the time is not representable
+      * in the system time_t
       */
       std::chrono::system_clock::time_point to_std_timepoint() const;
 

src/tests/data/dates.vec

@@ -3,6 +3,7 @@
 Date = 1970,01,01,0,0,0
 Date = 1998,04,23,14,37,28
 Date = 2037,12,31,23,59,59
+Date = 2038,01,19,3,14,7
 
 [valid.not_std]
 # these dates are valid but not representable as a std::system_clock::time_point
@@ -12,8 +13,12 @@ Date = 1969,12,31,23,59,59
 
 [valid.64_bit_time_t]
 # only valid if 64 bit std::time_t is used
-Date = 2038,01,01,0,0,0
+Date = 2038,01,19,3,14,8
 Date = 2083,05,20,8,30,9
+Date = 2200,07,04,19,30,0
+
+# 2262 problem
+Date = 2262,04,11,23,47,16
 
 [invalid]
 #Date = 2037,12,32,24,59,59