Thursday, December 27, 2007

Christmas Vacation Hacks


There's been discussion about Evolution not handling some brokenly rfc2047 encoded message headers recently, so I ported some workaround logic from GMime to Camel yesterday. I think this should turn a lot of frowns upside down when Evolution 2.22 is released. The new rfc2047 header decoder in Evolution is now more accepting than Thunderbird's decoder[1], so I hope this will satisfy everyone.

The new rfc2047 decoder will now handle the following cases:

  • encoded-words embedded inside other tokens (e.g n=?iso-8859-1?q?a=EF?=ve)
  • encoded-words with LWSP in the encoded-text section (e.g. =?iso-8859-1?q?Look ma! there's spaces!?=)
  • some encoded-word tokens with unencoded special chars in the encoded-text section (such as ? marks and other specials - obviously this can't always work if a special sequence occurrs)
  • encoded-word tokens with no LWSP between them
  • no longer aborts if the encoded-text cannot be completely converted to UTF-8 from the charset provided, instead it will attempt to find a more suitable charset to use for conversion and/or replace invalid byte sequences with a '?'
This should fix all of the more common broken-mailer cases, or at least all of the ones that are worth even bothering to try and work around.


Did some digging and discovered how to document more things using gtk-doc, so GMime's documentation has been getting improved. All of the public functions in GMime now appear in the documentation (I had forgotten to add some of the newer API additions to the gmime-sections.txt file) as well as began writing documentation for each of the doc sections (which I hadn't known how to document previously).

You can find up-to-the-minute GMime documentation here as I continue to chug away at expanding it.

While porting GMime's rfc2047 decoding logic to Evolution, I discovered some areas I could improve in GMime too.

1. After having ported my GMime decoder logic to Camel, I was curious to see how Thunderbird handled broken rfc2047 encoded headers and so had myself a peek at mozilla/netwerk/mime/src/nsMIMEHeaderParamImpl.cpp and noted that my new logic in Camel would handle everything that Thunderbird would handle and more.

I also took a peek at KMail's rfc2047 header decoding logic and discovered Evolution is now more flexible than it as well (again, Evolution now handles everything that KMail's decoder handles and more).

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