reject out-of-range day in grpc datetime IsValid

Author: netliomax25-code

grpc/src/ugrpc/datetime_utils.cpp

@@ -38,7 +38,9 @@ bool IsValid(const google::type::Date& grpc_date) {
     return (grpc_date.year() >= 1 && grpc_date.year() < 10'000) &&
            (grpc_date.month() >= 1 && grpc_date.month() <= 12) &&
            (grpc_date.day() >= 1 &&
-            std::chrono::day(grpc_date.day()) <= utils::datetime::DaysInMonth(grpc_date.month(), grpc_date.year()));
+            grpc_date.day() <= static_cast<int>(static_cast<unsigned>(
+                                   utils::datetime::DaysInMonth(grpc_date.month(), grpc_date.year())
+                               )));
 }
 
 #if __cpp_lib_chrono >= 201907L

grpc/tests/datetime_utils_test.cpp

@@ -149,6 +149,9 @@ TEST(DatetimeUtilsDateIsValid, BigMonth) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(
 TEST(DatetimeUtilsDateIsValid, NegativeDay) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(2025, 4, -10))); }
 TEST(DatetimeUtilsDateIsValid, BigDay) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(2025, 4, 50))); }
 TEST(DatetimeUtilsDateIsValid, DayDoesNotMatchMonth) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(2025, 4, 31))); }
+// day is a wire-controlled int32; values above 255 must not wrap into the valid range
+TEST(DatetimeUtilsDateIsValid, DayWrapsToZero) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(2025, 4, 256))); }
+TEST(DatetimeUtilsDateIsValid, DayWrapsIntoValidRange) { EXPECT_FALSE(ugrpc::IsValid(MakeDate(2025, 4, 286))); }
 
 #if __cpp_lib_chrono >= 201907L