[TIKA-2602] iCalendar not properly recognized as text/calendar

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Andreas Meier
• Created: 08/Mar/18 09:25
• Updated: 29/Oct/19 15:52

Description

At the moment the detection of text/calender is covered by the following mime-type-element:

  <mime-type type="text/calendar">
    <magic priority="50">
      <match value="BEGIN:VCALENDAR" type="string" offset="0">
        <match value="VERSION:2.0" type="string" offset="15:30"/>
      </match>
    </magic>
    <glob pattern="*.ics"/>
    <glob pattern="*.ifb"/>
    <sub-class-of type="text/plain"/>
  </mime-type>

This recognition will fail, if VERSION:2.0 is not the first property after BEGIN:VCALENDAR.
Since this is not always the case (check: https://tools.ietf.org/html/rfc5545 3.6. Calendar Components) recognition may fail for calendar objects with PRODID or other properties:

Section "4. iCalendar Object Examples" shows some of these cases:

       BEGIN:VCALENDAR
       PRODID:-//xyz Corp//NONSGML PDA Calendar Version 1.0//EN
       VERSION:2.0
       BEGIN:VEVENT
       DTSTAMP:19960704T120000Z
       UID:[e-mail]
       ORGANIZER:mailto:[e-mail]
       DTSTART:19960918T143000Z
       DTEND:19960920T220000Z
       STATUS:CONFIRMED
       CATEGORIES:CONFERENCE
       SUMMARY:Networld+Interop Conference
       DESCRIPTION:Networld+Interop Conference
         and Exhibit\nAtlanta World Congress Center\n
        Atlanta\, Georgia
       END:VEVENT
       END:VCALENDAR

or

       BEGIN:VCALENDAR
       METHOD:xyz
       VERSION:2.0
       PRODID:-//ABC Corporation//NONSGML My Product//EN
       BEGIN:VEVENT
       DTSTAMP:19970324T120000Z
       SEQUENCE:0
       UID:[e-mail]
       ORGANIZER:mailto:[e-mail]
       ATTENDEE;RSVP=TRUE:mailto:[e-mail]
       DTSTART:19970324T123000Z
       DTEND:19970324T210000Z
       CATEGORIES:MEETING,PROJECT
       CLASS:PUBLIC
       SUMMARY:Calendaring Interoperability Planning Meeting
       DESCRIPTION:Discuss how we can test c&s interoperability\n
        using iCalendar and other IETF standards.
       LOCATION:LDB Lobby
       ATTACH;FMTTYPE=application/postscript:ftp://example.com/pub/
        conf/bkgrnd.ps
       END:VEVENT
       END:VCALENDAR

I suggest to either
a) widen the offset of the VERSION-match from 15:30 to 15:200 or sth. like that (not so good approach, since we don't know how Long the PRODID might be)
or
b) to add sub-matches for CALSCALE, PRODID, METHOD. (This might still not cover everything, since there are x-prop and iana-prop properties. For now I can only confirm that there are PRODID or METHOD as first property after BEGIN:VCALENDAR.)

Regards

Andreas

Issue Links

• links to: https://en.wikipedia.org/wiki/ICalendar