Feedback-ID: ia2694551:Fastmail
Date: Fri, 24 Nov 2023 10:50:30 +0100
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael@paquier.xyz>
Cc: Ivan Trofimov <i.trofimow@yandex.ru>, pgsql-bugs@lists.postgresql.org
Subject: Re: libpq: pipeline mode might desynchronize client and server
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On 2023-Nov-24, Michael Paquier wrote:

> On Wed, Nov 22, 2023 at 03:13:46AM +0300, Ivan Trofimov wrote:

> > Libpq in pipeline mode considers '< 2TDCEZ' a sufficient response to
> > '> BDESS', when according to specification one more 'Z' is expected.
> > This leads to client <-> server desynchronization, when libpq parses the
> > very next message server sends (which is Z, as expected).
> > 
> > A bit more context and a MRE:
> > https://github.com/itrofimow/libpq_protocol_desync
> > 
> > I'm pretty sure that this branch https://github.com/postgres/postgres/blob/3af101ce8be8eeb0e8adc61e293b5d12989f68be/src/interfaces/libpq/fe-exec.c#L2124
> > should be adjusted to handle the case and do not match error response
> > against sync query.
> 
> Could you attach the test case to the original thread please (assuming
> that this is the same problem)?  If this data is deleted by github,
> then any data making a problem reproducible would be lost.

FWIW I started looking at this problem a couple of days ago.  I had not
noticed the previous thread.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"El hombre nunca sabe de lo que es capaz hasta que lo intenta" (C. Dickens)