Strange "IMAP connection broken (server response)" errors

[Kadlecsik József]

Hello,

On Fri, 6 Oct 2017, Jozsef Kadlecsik wrote:

> We upgraded one of our dovecot servers to debian stretch with dovecot 
> 2.2.27 and since then one of our users has been experiencing random IMAP 
> failures.
> 
> We enabled raw logging at the server side and it shows normal IMAP 
> commands/responses:
> 
> 1507292522.222427 * 6 FETCH (FLAGS () BODYSTRUCTURE ("text" "plain" 
> ("charset" "us-ascii")
>  NIL NIL "7bit" 4645 112 NIL NIL NIL NIL))
> 1507292522.222653 00000011 OK Fetch completed (0.006 + 0.000 secs).
> 
> On the client side the user runs alpine and the corresponding debug lines:
> 
> IMAP DEBUG 14:22:02.216167: 00000011 FETCH 6 (BODYSTRUCTURE FLAGS)
> 
> 14:22:02.217396
> IMAP 14:22:02 10/6 mm_notify bye: 
> {[127.0.0.1]:1555/imap/user="ha4aa"}INBOX: [CLOSED] IMAP connection broken 
> (server response)
> 
> 14:22:02.217471
> IMAP 14:22:02 10/6 mm_log error: [CLOSED] IMAP connection broken (server 
> response)
> 
> The "[127.0.0.1]:1555/imap/user="ha4aa" part in the log comes from an 
> socat inserted between the client and the server to check independently 
> the imap session. According to socat, the server response didn't reach 
> the client!:
> 
> 00000010 OK Fetch completed (0.005 + 0.000 secs).\r
> > 2017/10/06 14:22:02.216299  length=40 from=845 to=884
> 00000011 FETCH 6 (BODYSTRUCTURE FLAGS)\r
> 
> and here ends the socat log.

The date of the last rawlog line corresponds to an ssl debug log of 
dovecot (from the last run):

Oct 20 18:50:05 mail2 dovecot: imap-login: Debug: SSL error: SSL_read() 
failed: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init

I added the patch "openssl: Clear error queue after an incomplete 
SSL_shutdown", recompiled the package but it did not help.

Any help is highly welcomed!

Best regards,
Jozsef
--
E-mail : kadlecsik.jozsef at wigner.mta.hu
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Address: Wigner Research Centre for Physics, Hungarian Academy of Sciences
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