A and AAAA DNS query process in getaddrinfo()?

[Max Laier]

On Friday 10 August 2007, JINMEI Tatuya / 神明達哉 wrote:
> At Fri, 10 Aug 2007 11:52:09 +0800,
>
> blue <susan.lan at zyxel.com.tw> wrote:
> > When looking into kame-20070801-freebsd54-snap, the function,
> > _dns_getaddrinfo(), defined in getaddrinfo.c, will check if the
> > device gets any IPv4/global IPv6 address before sending out any
> > A/AAAA query by calling addrconfig() if the user does not specify the
> > family type (AF_UNSPEC). However, FreeBSD-CURRENT (known is going to
> > be FreeBSD7.0), does not do the process.
> >
> > Do we need to do the same check before sending out the A/AAAA query?
>
> I'm afraid just asking this question without providing a context could
> be misleading.  I guess this is a continuation of a thread of the
> snap-users at kame list:
>
> ftp://ftp.kame.net/pub/mail-list/snap-users/9541
> ftp://ftp.kame.net/pub/mail-list/snap-users/9544
>
> If so, we should discuss this with the understanding of why KAME-snap
> version behaves that way, specifically referring to Section 3
> (especially 3.4.1) of this document:
> http://v6fix.net/docs/wide-draft-v6fix.en
>
> We (KAME) thought the behavior was reasonable but we were also afraid
> this might be too experimental to incorporate to *BSD release
> versions at that time.  That's why it's not in the FreeBSD repository.
> I'm interested in what others think on this.  If others think this
> feature is reasonable, too, and want it, I'm happy to commit the
> change to the FreeBSD repository.

I agree with the reasoning in the document you reference above.  
getaddrinfo is a convenience resolver and thus it's a good thing to 
return reasonable defaults.  Not returning AAAA when there are no IPv6 
addresses around seems reasonable to me.  I'm not sure it's a good idea 
to go the other way (i.e. not sending A queries when there are no IPv4 
addresses), however.

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