Re: [Patch] fix broken decryption of s/mime messages loaded from imap

[JohnJackDoe tele2 de]

Hello all,

I am retired and use Balsa for my private email communication as well  
as for my part-time job. For the part-time job I have to retrieve  
GnuPG/MIME encrypted mail from an IMAP account. These mails I can't  
decrypt because Balsa reports always 'Balsa decryption failed: GPME:  
decryption failed: Decryption failed'. In order to check this I sent an  
encrypted email to myself and retrieved it from the IMAP account -  
decryption failed. Could it be that this is the same failure Albrecht  
reported? If yes, please Albrecht could you build a new Balsa package  
for me from git?

Many thanks.

Best regards,

John Jack Doe

On 09 Feb 2019 12:54:42, Albrecht Dreß wrote:
> Am 08.02.19 18:52 schrieb(en) Albrecht Dreß:
> > After digging through the code, I /think/ the problem is in  
> > libbalsa_mailbox_imap_fetch_structure() which loads only text/* and  
> > short messages completely (to be honest, I don't understand why  
> > multipart/* is working, though…).  At least, the attached trivial  
> > patch, just loading single-part S/MIME messages just as text/*,  
> > solves the issue for me.
>
> Thinking again about this issue, I guess this approach is not  
> completely correct.  If all multipart/* messages are handled at some  
> other place (are they?), shouldn't *all* other top-level content  
> types be loaded here?  The vast majority will (explicitly or  
> implicitly) be text/*, and application/pkcs7-mime is already somewhat  
> special.  But a message containing only a, say image/* or  
> application/pdf as the only payload is absolutely legal (although I  
> saw the latter with malspam attacks only…).
>
> Thus, the more appropriate approach would be
>
> --8<--------------------------------------------------------------------------------------
> diff --git a/libbalsa/mailbox_imap.c b/libbalsa/mailbox_imap.c
> index d85e377c1..2ba010b43 100644
> --- a/libbalsa/mailbox_imap.c
> +++ b/libbalsa/mailbox_imap.c
> @@ -2247,7 +2247,7 @@  
> libbalsa_mailbox_imap_fetch_structure(LibBalsaMailbox *mailbox,
>         LIBBALSA_MESSAGE_GET_LENGTH(message)<8192 ||
>         (message->headers &&
>          (!message->headers->content_type ||
> -         g_mime_content_type_is_type(message->headers->content_type,  
> "text", "*"))) ){
> +          
> !g_mime_content_type_is_type(message->headers->content_type,  
> "multipart", "*")))) {
>          /* we could optimize this part a little bit: we do not need  
> to
>           * keep reopening the stream. */
>          GMimeStream *stream =
> --8<--------------------------------------------------------------------------------------
>
> wouldn't it?
>
> Cheers,
> Albrecht.