DAVdroid doesn't understand America/Montevideo VTIMEZONE provided by Horde



  • Hi,

    hmmm - you will not like that but … thunderbird and other clients understand the way Horde communicates with them. Wouldn’t it be possible to make davdroid less vulnerable for nonconformant communication?

    regards


  • developer

    @daniu said:

    hmmm - you will not like that but … thunderbird and other clients understand the way Horde communicates with them.

    I guess they ignore the VTIMEZONE. Time to create some bug reports (or better yet, patches) if you want to support these projects 😉

    Wouldn’t it be possible to make davdroid less vulnerable for nonconformant communication?

    I don’t know how this should be possible. Do you mean ical4j (the iCalendar library used by DAVdroid) should interpret corrupt data randomly?

    But of course, if you have specific suggestions, please let me (or the author of ical4j) know.



  • Hi,

    of course not randomly. How does thunderbird interpret it? Obviously in a way nobody bothers - so the user does not even realize that anything is wrong. To be honest: I don’t know what VTIMEZONE is for and what it does but I do know that thunderbird interprets Horde’s communication so that the entries are synced and look correct (to me). (I assume that the protocol is supposed to work even if you sync with calenders with many different timezones - that is however a really rare usecase …) I knew that you would not like it (and I told you) but the point is still: thunderbird can sync with Horde, Davdroid cannot …

    Another point: in Horde bugtracker there is a solution for the problem:
    “After updating tzdata package to tzdata-2015f this problem has disappeared”

    I don’t have a glue who can apply this change and what that person has to do. Maybe I can solve the issue myself?

    regards


  • developer

    @daniu said:

    of course not randomly. How does thunderbird interpret it?

    I guess that it doesn’t at all, or it doesn’t right, which results in bugs like this: imported outlook event ignoring DAYLIGHT in VTIMEZONE.

    Obviously in a way nobody bothers - so the user does not even realize that anything is wrong.

    Exactly: it interprets data randomly (“nobody bothers”) where strict processing and error handling would be required. This results in non-defined event times, and in a bad case, you’ll come an hour late to your important meeting.

    To be honest: I don’t know what VTIMEZONE is for and what it does but I do know that thunderbird interprets Horde’s communication so that the entries are synced and look correct (to me). (I assume that the protocol is supposed to work even if you sync with calenders with many different timezones - that is however a really rare usecase …)

    It’s not that rare (business people who travel or schedule remote meetings between time zones etc.), and more important: for you, it’s only one this one time zone that has to work, but for other people there are others. So in sum, all time zones have to work.

    I don’t think ignoring VTIMEZONE is a good idea, and it also leads to various problems with servers (as far as I remember, DAVdroid did this in its earliest versions).

    In my experience, time zones and VTIMEZONE are a very complex topic and one of the biggest challenges in CalDAV (ok, there are recurring events, too ;)). You can’t just ignore them.

    I knew that you would not like it (and I told you) but the point is still: thunderbird can sync with Horde, Davdroid cannot …

    So please report this to Thunderbird: it synchronizes an event that it shouldn’t synchronize.

    Another point: in Horde bugtracker there is a solution for the problem:
    “After updating tzdata package to tzdata-2015f this problem has disappeared”

    I don’t have a glue who can apply this change and what that person has to do. Maybe I can solve the issue myself?

    Yes, please use the latest Horde version which uses the tzdata-2015 time zone version. If there’s no release yet, use bleeding edge.



  • Hi,

    OK OK … probably I am not the only one who cannot really do much about his Horde installation (because it is hosted by some provider) - therefore the wish to do what would help even it is not the right way. Fortunately I got a good provider and they updated the package mentioned in the error report already (udmedia.de btw).

    Problem solved …

    regards



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