New comment by ffobzb on void-packages repository

https://github.com/void-linux/void-packages/issues/39918#issuecomment-1306145298

Comment:
Thanks a lot for your investigations.

Yes, the Date header isn't from OpenSMTPd, and the Date header is not the problem because it shows local times.

The logging system (socklog) shows the time stamps in UTC, yes. But the time stamps from the processes in the logs use local time. In my example logfile above you can see that when OpenSMTPd starts (PID 2699) it logs correctly with local time, but when processing the mail within a forked process (PID 2703) it jumps to UTC. When stopping the process (PID 2699) it then jumps back to local time.

I don't think that this behaviour is intended or that OpenSMTPd uses generally UTC times in headers. Two reasons for that:
1. In the source code the time stamps for the Received header (and probably also for the logging) are generated in the function `time_to_text` in the source file `to.c`:
```
const char *
time_to_text(time_t when)
{
	struct tm *lt;
	static char buf[40];
	char *day[] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
	char *month[] = {"Jan","Feb","Mar","Apr","May","Jun",
			 "Jul","Aug","Sep","Oct","Nov","Dec"};
	const char *tz;
	long offset;

	lt = localtime(&when);
	if (lt == NULL || when == 0)
		fatalx("time_to_text: localtime");

#if HAVE_STRUCT_TM_TM_GMTOFF
	offset = lt->tm_gmtoff;
	tz = lt->tm_zone;
#elif defined HAVE_DECL_ALTZONE && defined HAVE_DECL_TIMEZONE
	offset = lt->tm_isdst > 0 ? altzone : timezone;
	tz = lt->tm_isdst > 0 ? tzname[1] : tzname[0];
#endif

	/* We do not use strftime because it is subject to locale substitution*/
	if (!bsnprintf(buf, sizeof(buf),
	    "%s, %d %s %d %02d:%02d:%02d %c%02d%02d (%s)",
	    day[lt->tm_wday], lt->tm_mday, month[lt->tm_mon],
	    lt->tm_year + 1900,
	    lt->tm_hour, lt->tm_min, lt->tm_sec,
	    offset >= 0 ? '+' : '-',
	    abs((int)offset / 3600),
	    abs((int)offset % 3600) / 60,
	    tz))
		fatalx("time_to_text: bsnprintf");

	return buf;
}
```
So the variable `lt` is filled with the libc function `localtime`, then the time zone is extracted etc. The intention is clear: The time stamps should be in the systems time zone. If time stamps should be always just UTC this function would be much simpler.

2. I tested the same on an OpenBSD system with OpenSMTPd. There the Received header and the logging uses time stamps in local time, as expected. And the source code in the concerning areas of `to.c` is the same between the OpenBSD version and the Linux/other version.

Regarding my system config for the time zone: It is set to CET/CEST, because `/etc/localtime` is a symlink to `/usr/share/zoneinfo/Europe/Berlin`, and this means the system is configured to use CET and not UTC.

Is your Fedora installation configured to use UTC as time zone? If no, then that would indicate that the problem is not Void specific, but Linux specific...

A configuration option for the time stamps does not exist - at least not a documented one.

My suspicion is still that the problem has to do with the fork resp. privilege drop to the _smtpd or _smtpq user. Somehow the configured system time zone disappears then.