Getting vmime::exception::invalid_response on email fetching

[paukonen]

Hello!

I received this exception while I was trying to fetch email with latest git version of vmime.
Response looks like this:
[^]* 4 FETCH (BODYSTRUCTURE (("text" "plain" ("charset" "utf-8") NIL NIL "8bit" 536 0 NIL NIL NIL NIL)("text" "html" ("charset" "utf-8") NIL NIL "8bit" 7130 0 NIL NIL NIL NIL) "alternative" ("boundary" NIL)))

Error is permanent.

[vincent-richard]

Hello!

Is this a new error, or did it also occur in previous versions?
Which is the IMAP server returning this?

At first sight, it seems "...("boundary" NIL)..." is an invalid syntax.
The IMAP RFC gives the following grammar for body-fld-param:

body-fld-param  = "(" string SP string *(SP string SP string) ")" / nil

And string is either a quoted or a literal, NIL is forbidden (not to be confused with nstring, which explicitly allows NIL).

Thanks,

Vincent

[paukonen]

It's not a new error, I also get this error on git version I downloaded some time ago (29.04.2016).

Server is imap.mail.ru.
I created test account last month, and it has several emails in INBOX.
I tried downloading this message with Thunderbird and it downloads email fine without any errors.

I'm attaching full vmime trace log, maybe it can help to understand the problem.
vmime.txt

Is there anything else I can send you? I can provide you with login and password to this test account to check this problem by yourself, if needed.

[paukonen]

Found couple of mentions of this problem with mail.ru server:
https://www.ietf.org/mail-archive/web/imapext/current/msg05442.html
jstedfast/MailKit#124

So the problem seems to be in imap server. Thunderbird just treats this error more lightly and receives message despite of the error. Windows Live Mail also receives this email. Could you please add some code replacing nil with empty string or something like that, so that message could be received?

[vincent-richard]

Thank you for all these information. I have fixed the issue by providing a parsing workaround in non-strict mode (the default).

[paukonen]

Thank you! Fix is working fine.