581523 - Lightning fails to honor MIME headers

Status: RESOLVED INVALID

(Calendar :: Import and Export, defect)

Description

[Brent Garber]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.7) Gecko/20100713 Firefox/3.6.7 ( .NET CLR 3.5.30729)
Build Identifier: 

Similar to Bug 565672 which was closed as invalid.  It was claimed: 

---
Please ensure that the content of the ics file is correctly stored in the UTF-8
character encoding as required in the iCalendar specification (RFC 5545).
---

Which is incorrect.  The RFC[1] actually states UTF8 is the *default* not the *required* encoding.

1 - http://tools.ietf.org/html/rfc5545#section-3.1.4

If served over HTTP and the following header is sent as a response:
Content-Type: text/calendar;charset=ISO-8859-1

Lightning still tries to parse this as UTF-8 which gives you:

Warning: There has been an error reading data for calendar: MeetUp. It has been placed in read-only mode, since changes to this calendar will likely result in data-loss.  You may change this setting by choosing 'Edit Calendar'. Error code: CAL_UTF8_DECODING_FAILED. Description: An error occured while decoding an iCalendar (ics) file as UTF-8. Check that the file, including symbols and accented letters, is encoded using the UTF-8 character encoding.

Reproducible: Always

Steps to Reproduce:
1. Correctly create a iCal file not using UTF8
2. Correctly send charset of actuall encoding as specified in the RFC
3. Watch Lightning break
Actual Results:  
Lightning wont read the feed

Expected Results:  
Lightning reads the feed

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.7) Gecko/20100713 Lightning/1.0b2 Thunderbird/3.1.1

Comment 1

[Stefan Sitter [:ssitter]]

Section 3.1.4 refers to the charset of an iCalendar property. Charset for text/calendar MIME type is mentioned in http://tools.ietf.org/html/rfc5545#section-8.1 :

Subject: Registration of media type text/calendar

      The "charset" parameter is defined in [RFC2046] for subtypes of
      the "text" media type.  It is used to indicate the charset used in
      the body part.  The charset supported by this revision of
      iCalendar is UTF-8.  The use of any other charset is deprecated by
      this revision of iCalendar; however, note that this revision
      requires that compliant applications MUST accept iCalendar streams
      using either the UTF-8 or US-ASCII charset.

In addition http://tools.ietf.org/html/rfc5545#section-6 states:

   Applications MUST generate iCalendar streams in the UTF-8 charset and
   MUST accept an iCalendar stream in the UTF-8 or US-ASCII charset.

Regarding the encoding of non-us-ascii characters http://tools.ietf.org/html/rfc5545#section-3.1 states:

     NON-US-ASCII  = UTF8-2 / UTF8-3 / UTF8-4
     ; UTF8-2, UTF8-3, and UTF8-4 are defined in [RFC3629]

All this leads me to the conclusion that as soon as any non-ascii char is used you must encode the ics file with UTF-8.

Comment 2

[Brent Garber]

Well I read that wrong then.  Could there be an 'broken implementation' compatability flag? Similar to Postfix's broken_sasl_auth_clients.

Comment 3

[Simon Paquet [:sipaq]]

Marking INVALID as per comment 1.

Please open up a new bug for your request in comment 2 about a "broken implementation" mode.