Fri, 10 Apr 2026 12:09:53 +0000 https://bugs.horde.org/ticket/4399 Broken iCalendar event timezone interoperabilty with Outlook & others When importing a calendar event into Kronolith (or viewing it in IMP) from a user in a different timezone Horde does not respect the timezone specified for the event and erroneously imports or shows the event as if it were scheduled for local time. Actually, if the sending application specifies the date / time as UTC (as Horde Kronolith does itself) then this does not apply and Horde handles it properly. However most applications do not specify events in that way and Horde does not handle them properly. The most notable application that does not work properly with Horde is of course Microsoft Outlook / Exchange. For example, I work near San Francisco (US/Pacific timezone) but my employer is based in Atlanta (US/Eastern timezone). If a coworker based in Atlanta sends me a calendar invite for a conference call that began at 9am Eastern time Kronolith will import and show it as being 9am Pacific time which would make me 3 hours late for the call if I rely on it. Fri, 08 Sep 2006 19:51:39 +0000 https://bugs.horde.org/ticket/4399#t23827 To be clear this is a problem with the iCalendar module in the Horde framework not in Kronolith. Fri, 08 Sep 2006 19:53:34 +0000 https://bugs.horde.org/ticket/4399#t23828 Are you going to upload your patch, too? Fri, 08 Sep 2006 19:58:37 +0000 https://bugs.horde.org/ticket/4399#t23831 Attached is a patch (against HEAD - 1 Sep 2006) that adds proper timezone handling to the Horde framework so that icalendar invitations / events sent from users in other timezones are viewed and imported properly. I did this patch the right way and the code conforms to the iCalendar specification (RFC2445). I have extensively tested it and I am satisfied that it interoperates correctly with all RFC conforming calendar applications including Microsoft Outlook / Exchange, Apple iCal, Mozilla Calendar and others. Further, the changes are all in one file and internal to the iCalendar object in the Horde framework so there are no changes that are necessary to the applications (Kronolith, IMP, etc.) Therefore, I believe this patch is ready for immediate integration into Horde CVS. The only externally visible change made (besides correct date / times!) is what gets stored in the calendar object when an invalid date-time stamp is encountered. Previously, it was not consistent but usually false would be stored. After this patch the original text from the invitation is stored so that it's not lost. After applying this patch you will need to run framework/install-packages.php -p iCalendar from the command line as root for it to take affect. One final caveat: because of the way the standard works the sending application specifies the exact times of the timezone's changes between daylight and standard time (if any). This means that if the powers that be change the dates for those changes and the sending application does not know about the new rules at the time the invitation is sent then there is potential for the receiving application (including this code) calculating the incorrect time. That is not a bug in the code but an invitation with a timezone component specified that is not correct. The sender will need to send an updated invitation after updating his computer / software to know about the new timezone rules or the recipient will need to manually change the time of the event. I bring this up of course because the US congress has changed when we in the US observe our time changes starting in 2007. If the sending application / computer of an invite does not know that and it encodes incorrect old information about its timezone but the recipient's application / computer knows about the new changes and the invitation falls on a date between when the sending application thought the time change would occur and when the receiving application knows that it actually will occur then the time derrived from the invitation will be off. Is that confusing enough? To put it simply, if you notice that some invitations sent by people in US timezones for events between March 11, 2007 and April 1, 2007 appear to be showing up witch a time that is incorrect by exactly one hour, it's not a bug in my code but a problem at the sender's end! Any software that imports calendar events using the standard may have this problem. Thank you, Carl E. Thompson Fri, 08 Sep 2006 20:02:58 +0000 https://bugs.horde.org/ticket/4399#t23832 Your patch uses str_ireplace, a PHP 5-only function. The iCalendar component (and nearly all of Horde for the moment) should work with PHP 4.3+. Please also read horde/docs/CODING_STANDARDS for a bunch of style/indent consistency issues, and upload a fixed patch. (At least a few places I see why the str_ireplace, but why did you use ireplace on array('\\n', '\\;', '\\:') ?) Mon, 11 Sep 2006 05:19:19 +0000 https://bugs.horde.org/ticket/4399#t23846 New patch: - Doesn't use str_ireplace() - Conform to Horde coding standards - Doesn't use scary strtotime() voodoo Chuck wrote: > (At least a few places I see why the str_ireplace, but why did you > use ireplace on array('\\n', '\\;', '\\:') ?) So that the letter 'n' is matched whether it is capital or lowercase. It is looking for the actual string backslash-N. Sun, 17 Sep 2006 06:50:06 +0000 https://bugs.horde.org/ticket/4399#t23946 I've committed a slightly modified version of your patch to HEAD (syntax tweaks and I moved the parseTZChild() function into the vTimezone class). Please check out the changes in HEAD and test (anyone, not just Carl), and Carl, if you could submit a test file that checks the timezone handling that would be _very_ helpful. If we have a test for this and it works well in HEAD I'll merge it to Horde 3.1.x. Thanks! Sun, 17 Sep 2006 21:57:00 +0000 https://bugs.horde.org/ticket/4399#t23987 Your changes to the patch seem fine and it works fine for me. When testing I used several .ics files I found using Google. Some are a bit strange but they encompass the range of what's out there. I have attached them. Thu, 21 Sep 2006 00:01:25 +0000 https://bugs.horde.org/ticket/4399#t24100 The test could be better, but this is merged now. Thanks! Sat, 23 Sep 2006 21:32:18 +0000 https://bugs.horde.org/ticket/4399#t24207