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From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: [musl] Incompatible behaviour of res_query(3) w.r.t. NXDOMAIN
Date: Mon, 24 Aug 2020 12:16:47 -0400	[thread overview]
Message-ID: <20200824161646.GH3265@brightrain.aerifal.cx> (raw)
In-Reply-To: <5232EC15-7E60-4D1F-BF3B-C31BFF998C06@rb67.eu>

On Sun, Aug 23, 2020 at 11:31:32PM +0200, Daniel Neri wrote:
>   Hello,
> 
> 
> Musl’s res_query(3) returns success for a query that results in an
> NXDOMAIN response, which disagrees with other common
> implementations.
> 
> Simple test case: https://t.rb67.eu/res_query.c
> 
> On Debian Linux, OpenBSD and FreeBSD this program prints:
> 
>   error: Unknown host
> 
> but on Alpine Linux edge (musl v1.2.1):
> 
>   success (size 91)

I think there's a good argument that this should be changed, but that
would require making res_* set h_errno, which would require making
h_errno thread-local -- which it probably should have been all along,
but the standard interfaces that used it, gethostby* etc., were
non-thread-safe anyway and thus it seemed unnecessary.

FWIW I think the musl behavior is *better* here (more informative to
the application), but usually it's preferable not to break the
existing (even if informal) contracts of the interfaces being
implemented than to be "better".

Rich

  reply	other threads:[~2020-08-24 16:17 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-23 21:31 Daniel Neri
2020-08-24 16:16 ` Rich Felker [this message]
2020-08-24 16:43   ` Rich Felker
2020-08-24 20:39     ` Daniel Neri
2020-08-24 21:36       ` Rich Felker
2020-08-24 21:04     ` Florian Weimer
2020-08-24 21:32       ` Rich Felker
2020-08-24 21:51         ` Daniel Neri
2020-08-24 22:09           ` Rich Felker
2020-08-25  3:26             ` Rich Felker
2020-08-25 13:56               ` Daniel Neri
2020-08-24 22:04         ` Florian Weimer
2020-08-24 22:13           ` Rich Felker

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