Re: [DNSOP] Re: getaddrinfo() and searching

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> On 27-sep-2007, at 3:33, Mark Andrews wrote:
> 
> >> So your issue that the results are inconsistent is certainly real.
> 
> >> I'd say that the best way to avoid this is not having a search domain
> >> at all, or at the very least not several.
> 
> > 	Which is a totally unreasonable suggestion.
> 
> It's not. Even without IPv6, having search domains means you can get  
> unexpected results. If that's not acceptable, don't complain, but put  
> a period behind your FQDNs.

	Please state were in RFC 952 a final period is legal in
	a hostname. 

	Remember applications take HOSTNAMES not DOMAIN NAMES.
	There are HOSTNAMES that you cannot store in the DNS.
	There are DOMAIN NAMES that are not legal HOSTNAMES.

> > 	The problem here is not the search but different stoping
> > 	critera depending apon the address families supported by
> > 	the host or requested by the application.
> 
> > 	We wrote a API that failed to account for the usual use
> > 	senario.  In fact the guidance in there is the direct
> > 	opposite of what should be done with the usual use senario.
> 
> I thought the solution would be hard or would be suboptimal in the  
> common case, but I think that doesn't have to be so.
> 
In my example, MacOS would go through the search domains and keep  
> going until it found AAAA records for IPv6 or IPv4+IPv6 applications  
> (and presumably look for A records if there were no AAAA records and  
> IPv4 was present/requested also).
> 
> So basically, both the "answers = 0, noerror" and "nxdomain"  
> responses trigger trying the next search domain. If we change this to  
> "answers = 0, noerror" means try the same FQDN again for an A record,  
> and "nxdomain" means move on to the next search domain, the results  
> for different permutations of IP version availability would all  
> result in connecting to the same FQDN = the first one with an address  
> that's compatible with current connectivity, rather than the first  
> one with an AAAA record if there is IPv6 connectivity.
> 
> > 	I'm saying we should go back and fix the specification for
> > 	getaddrinfo() so that it accounts for searching.
> 
> Volunteers...?

	If need be, yes.
 
> > 	We should also add a AI_NOSEARCH flag so that searching is
> > 	controlled directly rather than indirectly.
> 
> That's what the period terminating a domain name is for.

	Again you confuse domain names and hostname.
 
> > 	I've set Reply-To to ipv6@xxxxxxxx as this is more approriate
> > 	for 6man.
> 
> No, it's a DNS issue, so it should go to dnsop. dnsop people: see  
> discussion between Mark, Keith and me that started under the subject  
> "renumbering" on the ietf discussion list.

	I chose ipv6@xxxxxxxx (or it predecessor) because ipv6@xxxxxxxx
	was where getaddrinfo()s behaviour was spec'd out.  We need to
	at least give the 6man a chance to address it.
 
	Mark

> Everyone: feel free to prune some lists when you respond.  :-)
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews@xxxxxxx

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