Time Conversion Bug (Was: no email notifications sent)

[Eric Emerson]

Hi,
Have not seen anything on this in a bit, is there patch available for this
(Version 3.1.2)? I would hate to hit this again next year :)
Take it Easy
Eric

On Tue, Nov 3, 2009 at 8:09 AM, Ton Voon <ton.voon at opsera.com> wrote:

> Hi Albrecht,
>
> On 3 Dec 2008, at 20:01, Albrecht Dreß wrote:
>
> > Am 01.12.08 21:59 schrieb(en) Albrecht Dreß:
> >> I have a self-compiled nagios 3.0.5 running on a 64-bit Xeon box
> >> with Ubuntu 8.04 LTS.  Everything went perfectly (including
> >> notifications) until I upgraded from 3.0.1 (iirc) to 3.0.5 during a
> >> bigger service downtime (inter alia shifting the box into an other
> >> network etc).
> >
> > After adding tons of debug messages, I was finally able to track
> > down the problem.  The problem is that I added a german holiday in
> > the form
> >
> >        october 3       00:00-00:00
> >
> > In function (all inbase/utils.c) check_time_against_period(), the
> > start time was calculated by calculate_time_from_day_of_month() as
> > 1222988400 (Fri Oct  3 01:00:00 2008), but the end time as
> > 1222984800 (Fri Oct  3 00:00:00 2008), which is /before/ the start,
> > and therefore the time span was expanded to a whole year, i.e. the
> > end now was Oct 3, 2009...
> >
> > Looking deeper into function calculate_time_from_day_of_month(),
> > this is apparently caused by a wrong usage of the call to mktime(),
> > as the field tm_isdst is /not/ initialised properly.  The observed 1
> > hour offset seems to come from an earlier call to this function
> > which returned an active dst flag.
> >
> > According to the IEEE Std 1003.1 [1], the field tm_isdst /is/ used
> > in the time conversion, and should be set to -1 if the dst status is
> > unknown (you may want to write a small test app, setting this flag
> > to -1, 0 or 1 to observe the effect).  As mktime() is used
> > frequently in the code without properly initialising this field,
> > this seems to be a systematic bug which can trigger interesting
> > effects in nagios.
> >
> > Any opinions?
>
> As you are probably aware, this change has caused the DST bug that has
> affected a lot of users of Nagios 3.2.0.
>
> I have only reverted one instance of the tm_isdst field, which was
> specifically causing the rescheduling problem. There is a testcase in
> HEAD ( download from
> http://nagios.sourceforge.net/download/cvs/nagios-HEAD.tar.gz
>  && ./configure --enable-libtap && make all && make test) which tests
> the DST bug (see t-tap/check_timeperiods.c).
>
> However, I think some of the other isdst settings maybe causing other
> bugs, though I'm not sure.
>
> It would be helpful if you could add some test for the problem you
> have fixed, to prove that the functionality you expect continues to
> work. I'd be happy to apply to CVS if you have an updated
> check_timeperiods.c file.
>
> Ton
>
>
>
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