From: "Steven Levine" <ecs-isp@2rosenthals.com>
Message-ID: <667e6328.20.mr2ice.fgrirsq@earthlink.net>
Date: Fri, 28 Jun 2024 00:15:52 -0700
To: "eCS ISP Mailing List" <ecs-isp@2rosenthals.com>
In-Reply-To: <list-10070785@2rosenthals.com>
Subject: Re: [eCS-ISP] Bind 9.11.37 issue - ticket #784 - update
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In <list-10070785@2rosenthals.com>, on 06/28/24
   at 07:26 AM, "Paul Smedley" <ecs-isp@2rosenthals.com> said:

Hi Paul,

>I got around to looking at this this morning.@Steven I'm assuming the 
>select call at lib\isc\unix\socket.c=A0 is the one you had in mind to ad=
d 
>the timeout to?

Yes, that should be the one.  In the isc sources it's

lib\isc\unix\socket.c:4377
			cc =3D select(maxfd, manager->read_fds_copy,
				    manager->write_fds_copy, NULL, NULL);

The select is wrapped in a do while loop so the net effect of a timeout
should be to re-issue the select which is what we want.

BTW, I may have mentioned that I finally tracked down the code that cause=
s
the database dump to be corrupted on a slave dns server.  The code path i=
s

dns_master_dump3 ->
  opentmp ->
    isc_file_bopenunique ->
      isc_file_openuniquemode

because we have

lib\dns\masterdump.c:1826
	if (format =3D=3D dns_masterformat_text)
		result =3D isc_file_openunique(tempname, &f);
	else
		result =3D isc_file_bopenunique(tempname, &f);

The problem is since we use the unix version of file.c,
isc_file_bopenunique does not set O_BINARY.  This is technically wrong,
but not a problem on linux because O_TEXT and O_BINARY are effectively
nops.

In our case the dump file that should be binary gets spurious NLs inserte=
d
and the resulting binary database file is corrupt.  This slows down the
slave server a bit because it needs to fully rebuild its internal databas=
e
which means it needs to contact the master dns.

I'm sure the corruption would be logged if the logging was configured to
log this kind of error.

Fixing this is a bit messy.  Since we have

lib\isc\unix\file.c:388
isc_result_t
isc_file_bopenuniquemode(char *templet, int mode, FILE **fp) {
	return (isc_file_openuniquemode(templet, mode, fp));
}

There's no easy way to pass the O_BINARY flag without creating a helper
function that both isc_file_bopenuniquemode and isc_file_openuniquemode
can call.  The helper function would take an additional argument that
would pass either O_TEXT or O_BINARY.


Steven

-- 
----------------------------------------------------------------------
"Steven Levine" <steve53@earthlink.net>  Warp/DIY/BlueLion etc.
www.scoug.com www.arcanoae.com www.warpcave.com
----------------------------------------------------------------------