From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: libpq: Be strict about cancel key lengths
Date: Fri, 22 Aug 2025 11:45:06 +0000
Message-ID: <E1upQCf-0017pU-1P@gemulon.postgresql.org> (raw)
libpq: Be strict about cancel key lengths
The protocol documentation states that the maximum length of a cancel
key is 256 bytes. This starts checking for that limit in libpq.
Otherwise third party backend implementations will probably start
using more bytes anyway. We also start requiring that a protocol 3.0
connection does not send a longer cancel key, to make sure that
servers don't start breaking old 3.0-only clients by accident. Finally
this also restricts the minimum key length to 4 bytes (both in the
protocol spec and in the libpq implementation).
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Jacob Champion <jchampion@postgresql.org>
Discussion: https://www.postgresql.org/message-id/df892f9f-5923-4046-9d6f-8c48d8980b50@iki.fi
Backpatch-through: 18
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/e411a8d25a4b39e5a896f765ca91636057e261fc
Modified Files
--------------
doc/src/sgml/protocol.sgml | 2 +-
src/interfaces/libpq/fe-protocol3.c | 21 +++++++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
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To: pgsql-committers@postgresql.org
Cc: heikki.linnakangas@iki.fi, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: libpq: Be strict about cancel key lengths
In-Reply-To: <E1upQCf-0017pU-1P@gemulon.postgresql.org>
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