Re: [Nmh-workers] mhshow: invalid QUOTED-PRINTABLE encoding

[pmaydell]

Joel Uckelman wrote:
>I see what's causing the problem now, sort of. This URL appears in a footer
>appended by SourceForge:
>
>   http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
>
>The message has in it's header
>   
>   Content-Transfer-Encoding: quoted-printable
>
>which results in the '=cl' in the appended footer being interpreted as a
>quoted-printable character code. The tiny attached example message is
>sufficient to reproduce the behavior I saw.

You're right that this is not valid Q-P encoding. RFC 2045 says
(in section 6.7):

#    (2)   An "=" followed by a character that is neither a
#          hexadecimal digit (including "abcdef") nor the CR
#          character of a CRLF pair is illegal.  This case can be
#          the result of US-ASCII text having been included in a
#          quoted-printable part of a message without itself
#          having been subjected to quoted-printable encoding.  A
#          reasonable approach by a robust implementation might be
#          to include the "=" character and the following
#          character in the decoded data without any
#          transformation and, if possible, indicate to the user
#          that proper decoding was not possible at this point in
#          the data.

I think we should make nmh follow this recommendation (and the
others like it in that section); it's sensible enough and it makes
nmh more usable in the face of duff input.

-- PMM