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Re: DNS RRTYPEs, the difficulty with (was: WG Review: Recharter of Hypertext Transfer Protocol Bis (httpbis))

2012-02-24 16:57:14

In message <20120224171427(_dot_)GJ48576(_at_)mail(_dot_)yitter(_dot_)info>, 
Andrew Sullivan writes:
cc:s trimmed.  I'm not on the w3c list anyway, and I don't think the
IESG cares about this detail.

On Fri, Feb 24, 2012 at 04:58:36PM +0100, Patrik Fältström wrote:

Because people disagree on whether it is actually hard to get new 
RRTYPEs deployed.

I for example do completely disagree on it being hard. Sure, your user 
interface in the gui of your favorite $EDITOR might not support the new 
RRTYPE, but should that constrain deployment of good standards?


Before those who think DNS weenies never listen to real-world problems
jump in, I want to point out what _I_ understand to be a problem.  If
you're a DNS geek, then the natural thing to think is, "This is easy.
You just send a well-crafted UDP packet.  How hard could that be?
Once the typecode is assigned, what's the problem with sending an
unknown RR?"

If you're most application programmers, however, the entire conversation
ended at "send a well-crafted UDP packet".  Your libraries don't
support injecting well-crafted UDP packets, and you have no idea how
to do that, and it's incredibly stupid, and why would anyone think
that was reasonable anyway?

If you're most sysadmins, the entire conversation ended at "My tools
don't know what TYPE1234 is."  

If we seriously think that DNS RRTYPEs ought to be useful extensions
to people, we're going to have to make them _easy_ to deploy, not just
possible.  I have no idea how to solve this problem, though.

Best,

A

It's a simple library call in Windows to get SRV records returned.  What
windows doesn't have is the ability to lookup new types but SRV has been
supported for over a decade now.

        DNS_STATUS WINAPI DnsQuery(
          __in         PCTSTR lpstrName,
          __in         WORD wType,
          __in         DWORD Options,
          __inout_opt  PVOID pExtra,
          __out_opt    PDNS_RECORD *ppQueryResultsSet,
          __out_opt    PVOID *pReserved
        );

http://msdn.microsoft.com/en-us/library/windows/desktop/ms682016(v=vs.85).aspx

Posix: though you do have to parse the result.
int
res_query(const char *dname, int class, int type, u_char *answer, int anslen);

There are libraries that will extact the records and return them
as a list of length data blobs.  You just need to parse the individual
records.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka(_at_)isc(_dot_)org
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