Re: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection
Date
Msg-id 1675678.1700665886@sss.pgh.pa.us
Whole thread Raw
In response to BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection  (PG Bug reporting form <noreply@postgresql.org>)
Responses Re: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection  (Lars Kanis <lars@greiz-reinsdorf.de>)
List pgsql-bugs
PG Bug reporting form <noreply@postgresql.org> writes:
> The error "GSSAPI caller failed to retransmit all data needing to be
> retried" is raised here:
>
https://github.com/postgres/postgres/blob/eeb0ebad79d9350305d9e111fbac76e20fa4b2fe/src/interfaces/libpq/fe-secure-gssapi.c#L110
> It happens only in non-blocking mode over GSSAPI encrypted connections. It
> isn't reliable and depends on the network timing. When sending a 7MB file in
> alternating pieces of 27KB and 180 Byte per PQputCopyData() there is a 50%
> chance to get the failure over the local network. It doesn't happen if TLS
> is used instead.

Hmm.

> The issue is fixed if I change libpq at either pqPutMsgEnd() or at
> pg_GSS_write().

Both of those seem like pretty obviously wrong "fixes".  However,
I'm not quite sure I see the problem clearly enough to propose
a fix I'd believe in.

> Unfortunately so far I'm unable to provide a repro script. Maybe the above
> information is enough to understand the problem.

A repro script would be really really helpful here.

            regards, tom lane



pgsql-bugs by date:

Previous
From: PG Bug reporting form
Date:
Subject: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection
Next
From: Tom Lane
Date:
Subject: Re: BUG #18210: libpq: PQputCopyData sometimes fails in non-blocking mode over GSSAPI encrypted connection