334222 - Support "Content-Transfer-Encoding: uuencode" (MSOE4)

Status: UNCONFIRMED

(MailNews Core :: MIME, enhancement)

Description

[Kalle Olavi Niemitalo]

User-Agent:       ELinks/0.12.GIT
Build Identifier: version 3 alpha 1 (20060416)

A user of Microsoft Outlook Express 4 sent an attachment that Mozilla
Thunderbird is unable to open or save as a file.  If I right-click the
attachment and select Open from the menu, there is no error dialog box
but nothing happens.  If I select Save As instead, Mozilla asks for a
file name but neither creates the file nor says why.  However,
Microsoft Outlook Express 6 is able to display and save the
attachment.

The attachment in question has a "Content-Transfer-Encoding: uuencode"
header but lacks "begin" and "end" lines.  Instead, the encoded file
data fills the entire body of the body part.  This is not a standard
MIME format but it's apparently in use, and so Thunderbird needs to
either support it or give a clear error message, such as:

  Mozilla Thunderbird cannot use the attachment "attachment.txt"

  This attachment was sent using an unsupported variant of the
  "uuencode" format.  Mozilla Thunderbird can neither display the
  attachment nor save it as a file.

  To see the attachment, you can:

  * Save the entire message to a file and try opening it with some
    other email program, if you have one.  The sender seems to be
    using the "Microsoft Outlook Express 4.72.2106.4" program;
    if you have the same one, try it first.

  * Ask the sender to resend the attachment using the standard
    "base64" format.  Mozilla Thunderbird fully supports base64.
 
I tested on two systems:

- Mozilla Thunderbird 1.5 on Microsoft Windows.
- Today's CVS version (version 3 alpha 1 (20060416)) on Debian
  GNU/Linux, compiled with debugging.

The latter outputs the following messages to its tty when I click
Open.  There is no output to the JavaScript console.

###!!! ASSERTION: couldn't get message header: 'PR_FALSE', file /home/kalle/src/MIRROR/mozilla/mailnews/local/src/nsMailboxProtocol.cpp, line 436
WARNING: NS_ENSURE_TRUE(NS_SUCCEEDED(rv)) failed: file /home/kalle/src/MIRROR/mozilla/mailnews/local/src/nsMailboxService.cpp, line 642
WARNING: NS_ENSURE_TRUE(msg) failed: file /home/kalle/src/MIRROR/mozilla/mailnews/local/src/nsMailboxUrl.cpp, line 495
WARNING: NS_ENSURE_TRUE(NS_SUCCEEDED(rv)) failed: file /home/kalle/src/MIRROR/mozilla/mailnews/local/src/nsMailboxUrl.cpp, line 525

I also put a breakpoint in NS_DebugBreak_P, selected Open, and took a
backtrace.  I'll attach that one separately.


Reproducible: Always

Steps to Reproduce:
1. Save as a file the message I'll be attaching shortly.
2. Open this file via "Open Saved Message".
3. Right-click "attachment.txt" in the attachments list and choose Open.

Actual Results:  
Nothing happens in the UI, but an assertion failure and some warnings appear in the tty where I started the program.

Expected Results:  
Should either display the text of the attachment or describe why it cannot do that.

Comment 1

[Kalle Olavi Niemitalo]

Attachment: privacy-censored version of the undecodable message

Comment 2

[Kalle Olavi Niemitalo]

Attachment: GDB backtrace for breakpoint at NS_DebugBreak_P trying to Open the attachment

Comment 3

[Mike Cowperthwaite]

Per RFC 1341
  <http://www.w3.org/Protocols/rfc1341/5_Content-Transfer-Encoding.html>
"uuencode" is not a legal value for Content-Transfer-Encoding.

Do you have any idea if more current versions of Outlook still generate such attachments?  I suspect they do not.

Comment 4

[Kalle Olavi Niemitalo]

I don't know what later versions of Outlook send, and I agree that "uuencode" is not a standard Content-Transfer-Encoding.  However, my point was that if your application cannot save or display the attachment, then it should give an error message of some kind, so that the user isn't left thinking she saved the file to the wrong folder.  (It would be even better to skip the Save As dialog and display the error right away, but it's OK with me if that part is not implemented.)

Comment 5

[Tony Mechelynck [:tonymec]]

Hm. According to http://en.wikipedia.org/wiki/Uuencoding, "[uuencoding] has now been largely replaced by MIME and yEnc. With MIME, files that might have been uuencoded are transferred with base64 encoding."

I suspect this is (if it hasn't yet) soon going to become a nonissue as uuencoded messages disappear (have disappeared?) from the Net. Reporter (Kalle Olavi Nimitialo), what do you think?

Oh, and BTW, have you kept the original (uncensored) mail, and what happens when you try to open the attachment with a recent version of Thunderbird or SeaMonkey?

Comment 6

[Kalle Olavi Niemitalo]

It seems I do not have the original mail.