MBOX-Line: From blong at google.com  Fri Mar  7 07:34:40 2014
To: imap-protocol@u.washington.edu
From: Brandon Long <blong@google.com>
Date: Fri Jun  8 12:34:52 2018
Subject: [Imap-protocol] Is it okay/common for servers to ignore
 commands sent before the greeting? (gmail seems to?)
In-Reply-To: <5319E04C.3070105@mozilla.com>
References: <5319E04C.3070105@mozilla.com>
Message-ID: <CABa8R6v9vL5KKx9ArrZ7Fr_nu3uL90fwWTr+Z2W+7960i=Rz9A@mail.gmail.com>

Is this behavior new?

We're just finishing the rollout of a new IMAP proxy, its possible its a
bug in the new impl.

Brandon
On Mar 7, 2014 7:06 AM, "Andrew Sutherland" <asuth@mozilla.com> wrote:

> We're seeing a problem in the Firefox OS Gaia e-mail app where if we
> manage to send our "A1 CAPABILITY" request to the gmail IMAP server
> (initial-TLS imaps/993) before it sends its greeting, it acts like it never
> hears the request.  Our not-so-clever state machine hangs until the
> connection times out.
>
> There's more details and pcap dumps at https://bugzil.la/977867#c21 but
> basically we sometimes manage to get that request in the same TCP packet as
> the conclusion of TLS setup.  The TCP/TLS packet with the server greeting
> ACKs that packet, so it's quite conceivable our request is managing to fall
> into a very specific edge case/race.
>
> The spec does not seem to have a final word on this, although the state
> flow diagram in http://tools.ietf.org/html/rfc3501#section-3 does seem to
> imply that it's bad form to not wait for the server greeting.  While I
> think it's clear that for gmail we need to wait for the server greeting, I
> am wondering if this is just an unusual complication/bug of gmail's likely
> more complicated server architecture.  I'd expect a server intentionally
> being pedantic to issue a NO or BAD request...
>
> Thoughts / has anyone seen servers that intentionally or accidentally get
> upset in cases like this?
>
> Thanks,
> Andrew
>
> PS: We do have a lot of round-trip fat in our connection establishment, so
> it's not the end of the world to explicitly wait for the server greeting in
> all cases, but if it's just gmail (and we appropriately add some improved
> timeout logic that triggers a persistent quirk for the server), I could see
> it make sense to continue not waiting for the greeting.
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