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Subject: Re: Intended CNAME query behaviour

Re: Intended CNAME query behaviour

From: Brad House <brad_at_brad-house.com>
Date: Tue, 25 Feb 2020 07:08:57 -0500

Replying on #303 on GitHub.

On 2/24/20 6:38 PM, Thomas Walton wrote:
> Hello,
>
> I have created https://github.com/c-ares/c-ares/issues/303 because c-ares returns a SUCCESS status when it just
> receives a CNAME in response to a query (with no A or AAAA name provided).  I consider this to be a bug, and clearly
> the test at
> https://github.com/c-ares/c-ares/blob/b9eb3a0cfe7f50a3eaa8a1755ae57f7657931e3e/test/ares-test-parse-a.cc#L134 was
> supposed to check this, but the test is broken and doesn't work.  When the test is corrected, it fails.  However, this
> then clashes with test ParseAReplyJustCname, which is essentially testing the same case and checking for a different
> result.
>
> However, there is a comment in the code implying that this behaviour of returning a success for a CNAME only lookup is
> intentional.  This was added in https://github.com/c-ares/c-ares/commit/2c63440127feed70ccefb148b8f938a2df6c15f8 many
> years ago.
>
> What is the intended behaviour of c-ares in cases like this?  How should CNAME queries be handled?  Is there even a
> good way of reconciling these two requirements?
>
> I am happy to try to write a patch for this issue, but I do not want to break existing useful behaviour.
>
> Regards,
>
> Thomas
Received on 2020-02-25