Re: magic numbers in mm-view.el

[Simon Josefsson <jas@extundo.com>]

david.goldberg6@verizon.net (David S. Goldberg) writes:

> If I use the #secure tag to send an encrypted s/mime email to others
> and include a copy for myself, I am unable to read my copy in Gnus.  I
> am able to decrypt and verify it (assuming it's signed as well) by
> manually running Openssl on the message file and am also able to do so
> in Thunderbird.  Oddly enough, if I build a multipart structure for
> the message using #multipart instead of #secure I don't have this
> problem.  But because the structure of the message is apparently not a
> problem for OpenSSL or Thunderbird, I believe that the problem is that
> the mm-pkcs7-enveloped-magic variable is not sufficient to cover all
> cases.
>
> Running (pp mm-pkcs7-enveloped-magic) gives
>
> "0\\(€\\|.\\|‚..\\|ƒ...\\)\x06	\\*†H†÷\r\x01\a\x03"
>
> So it's already a regular expression.  Here's what I see:
>
> "0‚\nÍ\x06	*†H†÷\r\x01\a\x03"
>
> The problem is that the '\n' after the \202 does not match the . in
> the regular expression.  It seems it shouldn't be too hard to fix.
> Just put [.\n] instead of just . in those locations.  However, in
> mm-view.el we have
>
> (defvar mm-pkcs7-enveloped-magic
>   (mm-string-as-unibyte
>    (mapconcat 'char-to-string
> 	      (list ?\x30 ?\x5c ?\x28 ?\x80 ?\x5c ?\x7c ?\x81 ?\x2e ?\x5c
> 		    ?\x7c ?\x82 ?\x2e ?\x2e ?\x5c ?\x7c ?\x83 ?\x2e ?\x2e
> 		    ?\x2e ?\x5c ?\x29 ?\x06 ?\x09 ?\x5c ?\x2a ?\x86 ?\x48
> 		    ?\x86 ?\xf7 ?\x0d ?\x01 ?\x07 ?\x03) "")))
>
> And I am unsure how to work the fix into that construct.  I'd be glad
> to do it but need a bit of guidance on how to translate the characters.

Either you could simply replace those '.' with \(.\|\n\), but I think
maintainability suggest getting rid of the entire char-list and
replace it with something simpler.  Perhaps you can use `format' and
have the argument contain the printable characters, and regexp
keywords, and use %c or something for the escaped characters.