FormatException in an invitation with start and end date sent via GMX

[ThePeat94]

Hello,

I was trying to parse a invitation for a meeting, having a start and enddate (not allday). Following error occured:

Error in ConvertMailMessagesToMeetings! System.FormatException: String was not recognized as a valid DateTime.
   at System.DateTimeParse.Parse(String s, DateTimeFormatInfo dtfi, DateTimeStyles styles, TimeSpan& offset)
   at System.DateTimeOffset.Parse(String input)
   at Ical.Net.Serialization.iCalendar.Serializers.DataTypes.UtcOffsetSerializer.GetOffset(String rawOffset) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\Serializers\DataTypes\UTCOffsetSerializer.cs:line 42
   at Ical.Net.Serialization.iCalendar.Serializers.DataTypes.UtcOffsetSerializer.Deserialize(TextReader tr) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\Serializers\DataTypes\UTCOffsetSerializer.cs:line 31
   at Ical.Net.Serialization.iCalendar.Serializers.DataMapSerializer.Deserialize(TextReader tr) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\Serializers\DataMapSerializer.cs:line 56
   at Ical.Net.Serialization.iCalendar.iCalParser.property(ISerializationContext ctx, ICalendarPropertyListContainer c) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\iCalParser.cs:line 292
   at Ical.Net.Serialization.iCalendar.iCalParser.component(ISerializationContext ctx, ISerializerFactory sf, ICalendarComponentFactory cf, ICalendarObject o) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\iCalParser.cs:line 415
   at Ical.Net.Serialization.iCalendar.iCalParser.component(ISerializationContext ctx, ISerializerFactory sf, ICalendarComponentFactory cf, ICalendarObject o) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\iCalParser.cs:line 420
   at Ical.Net.Serialization.iCalendar.iCalParser.icalbody(ISerializationContext ctx, ICalendar cal) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\iCalParser.cs:line 207
   at Ical.Net.Serialization.iCalendar.iCalParser.icalendar(ISerializationContext ctx) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\iCalParser.cs:line 144
   at Ical.Net.Serialization.iCalendar.Serializers.CalendarSerializer.Deserialize(TextReader tr) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\Serializers\CalendarSerializer.cs:line 66
   at Ical.Net.Serialization.iCalendar.Serializers.SerializerBase.Deserialize(Stream stream, Encoding encoding) in C:\git\ical.net\v2\ical.net\Serialization\iCalendar\Serializers\SerializerBase.cs:line 39
   at Ical.Net.Calendar.LoadFromFile(String filepath, Encoding encoding, ISerializer serializer) in C:\git\ical.net\v2\ical.net\Calendar.cs:line 65
   at Ical.Net.Calendar.LoadFromFile(String filepath) in C:\git\ical.net\v2\ical.net\Calendar.cs:line 30
   at MeetingTestTool.Classes.MeetingParser.ConvertMailMessagesToMeetings(List`1 mailMessages) in D:\SVN\Azubi\HR\MeetingTestTool\MeetingTestTool\Classes\MeetingParser.cs:line 31

Test Method (contains content of the invitation):

public static void ParseMeetingWithDuration()
{
	const string ical =
@"BEGIN:VCALENDAR
PRODID:-//1&1 Mail & Media GmbH/GMX Kalender Server 3.10.0//NONSGML//DE
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:REQUEST
BEGIN:VEVENT
DTSTAMP:20170207T113248Z
DTEND;TZID=Europe/Brussels:20170207T093000
DTSTART;TZID=Europe/Brussels:20170207T083000
SUMMARY:neue testbesprechung
ATTENDEE;PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;[email protected]:MAILTO:[email protected]
ATTENDEE;PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;[email protected]:MAILTO:[email protected]
ORGANIZER;CN=Max Mustermann:MAILTO:[email protected]
DESCRIPTION:blubb
LOCATION:am neuen testort
UID:d950915c-d667-4e57-8b69-221b7bb8548d.kalender.gmx.net
SEQUENCE:0
END:VEVENT
BEGIN:VTIMEZONE
TZID:Europe/Brussels
TZURL:http://tzurl.org/zoneinfo/Europe/Brussels
X-LIC-LOCATION:Europe/Brussels
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:19810329T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19961027T030000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
BEGIN:STANDARD
TZOFFSETFROM:+001730
TZOFFSETTO:+001730
TZNAME:BMT
DTSTART:18800101T000000
RDATE:18800101T000000
END:STANDARD
BEGIN:STANDARD
TZOFFSETFROM:+001730
TZOFFSETTO:+0000
TZNAME:WET
DTSTART:18920501T120000
RDATE:18920501T120000
END:STANDARD
BEGIN:STANDARD
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19141108T000000
RDATE:19141108T000000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:19160501T230000
RDATE:19160501T230000
RDATE:19170416T020000
RDATE:19180415T020000
RDATE:19400520T030000
RDATE:19430329T020000
RDATE:19440403T020000
RDATE:19450402T020000
RDATE:19460519T020000
RDATE:19770403T020000
RDATE:19780402T020000
RDATE:19790401T020000
RDATE:19800406T020000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19161001T010000
RDATE:19161001T010000
RDATE:19170917T030000
RDATE:19180916T030000
RDATE:19421102T030000
RDATE:19431004T030000
RDATE:19440917T030000
RDATE:19450916T020000
RDATE:19461007T030000
RDATE:19770925T030000
RDATE:19781001T030000
RDATE:19790930T030000
RDATE:19800928T030000
RDATE:19810927T030000
RDATE:19820926T030000
RDATE:19830925T030000
RDATE:19840930T030000
RDATE:19850929T030000
RDATE:19860928T030000
RDATE:19870927T030000
RDATE:19880925T030000
RDATE:19890924T030000
RDATE:19900930T030000
RDATE:19910929T030000
RDATE:19920927T030000
RDATE:19930926T030000
RDATE:19940925T030000
RDATE:19950924T030000
END:STANDARD
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:WET
DTSTART:19181111T120000
RDATE:19181111T120000
RDATE:19191005T000000
RDATE:19201024T000000
RDATE:19211026T000000
RDATE:19221008T000000
RDATE:19231007T000000
RDATE:19241005T000000
RDATE:19251004T000000
RDATE:19261003T000000
RDATE:19271002T000000
RDATE:19281007T030000
RDATE:19291006T030000
RDATE:19301005T030000
RDATE:19311004T030000
RDATE:19321002T030000
RDATE:19331008T030000
RDATE:19341007T030000
RDATE:19351006T030000
RDATE:19361004T030000
RDATE:19371003T030000
RDATE:19381002T030000
RDATE:19391119T030000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:WEST
DTSTART:19190301T230000
RDATE:19190301T230000
RDATE:19200214T230000
RDATE:19210314T230000
RDATE:19220325T230000
RDATE:19230421T230000
RDATE:19240329T230000
RDATE:19250404T230000
RDATE:19260417T230000
RDATE:19270409T230000
RDATE:19280414T230000
RDATE:19290421T020000
RDATE:19300413T020000
RDATE:19310419T020000
RDATE:19320403T020000
RDATE:19330326T020000
RDATE:19340408T020000
RDATE:19350331T020000
RDATE:19360419T020000
RDATE:19370404T020000
RDATE:19380327T020000
RDATE:19390416T020000
RDATE:19400225T020000
END:DAYLIGHT
BEGIN:DAYLIGHT
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:19440903T000000
RDATE:19440903T000000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19770101T000000
RDATE:19770101T000000
END:STANDARD
END:VTIMEZONE
END:VCALENDAR";
	try
	{
		// With the given string it throws a FormatException
		IICalendarCollection meetingInvitation = Calendar.LoadFromStream(new StringReader(ical));

		/* Further processing like reading the organizer, attendees, start, end, location...
		 * ...
		 * ...
		 * ...
		 */
	}
	catch (Exception ex)
	{
		// Log Error
	}
}

The parsing process is successful, when I delete all standard sections. It is also parsing successfully using allday meetings. This invitation was sent via GMX. Sent invitations from Outlook or Thunderbird are working fine.

Greetings

[rianjs]

Yup, looks like an offset parsing bug. Not a huge surprise, the RFC spec for an offset differs from .NET's offset parsing semantics.

I have a fix, and I should have time to publish it tomorrow.

[aluxnimm]

this is a duplicate of #102

[ThePeat94]

Thank you rianjs, for taking time fixing this, I really appreciate it.

[rianjs]

Thanks, @aluxnimm

Fix published in nuget version 2.2.32:
https://www.nuget.org/packages/Ical.Net