Subject: [DNSOP] attrleaf

From: Paul Vixie <[email-masked]>
Date: Tue, 28 Mar 2017 10:03:03 -0700

i got underscores wrong in SRV. it may be that we should not follow that
track at all.

in C at that time, we were renaming our externally reachable library
symbols to add _ on the front (#define foo _foo), so that a compilation
which did not import that library (#include <foo.h>) would be able to
use those symbols locally without conflict. that's what i thought i was
doing with SRV, but as i said at DNSOP yesterday, that only worked when
there was a single use of _, and failed when other users of _ came along.

what SRV should have done was ask for a new registry of _ names, and
allocate exactly one of these, and hide its details under that label. so
instead of _telnet._tcp.servicename, it ought to have been
telnet.tcp._service.servicename.

if this is what we should have done, then it may be that the best thing
to do at this stage is, that. as in, declare the SRV got it wrong, and
note that _tcp and _udp have been camped upon by SRV, wrongly. all of
the service protocol names (_telnet, etc) need not be counted, since
they hide under a _tcp or _udp label.

-- 
P Vixie

---

From: Dave Crocker <[email-masked]>
Date: Tue, 28 Mar 2017 12:23:08 -0500

> they hide under a _tcp or _udp label.

Paul,

Coulda, shoulda, didn't.  Installed base.  Oh for the magic reversal wand.

There is already massive use of underscore names.

Deep aesthetic pain notwithstanding, there hasn't been a groundswell of 
operational complaints that would be needed to reverse this many years 
and such widespread use of the convention.

d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net

---

From: Paul Vixie <[email-masked]>
Date: Tue, 28 Mar 2017 10:46:37 -0700

> and such widespread use of the convention.

i don't think it's wise to estimate damage by observed complain level.
if _ is now in world wide use for all kinds of stuff, you can still say
that SRV got it wrong, and that the recommended way to do this kind of
thing is different from what SRV did. you could also do what a lot of
operating system developers had to do about _ use with C, which is use
two underscores in the next design, whose use will be better policed.

-- 
P Vixie

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From: "John Levine" <[email-masked]>
Date: 28 Mar 2017 18:37:40 -0000

>thing is different from what SRV did.

I don't see how this is relevant to attrleaf.  This draft collects
existing uses of underscore prefixed names, and says how to add new
names if and when they're defined.  It's not offering advice that
underscore names are wonderful, it's recognizing the ones that are in
use now.

R's,
John

---

From: Paul Vixie <[email-masked]>
Date: Tue, 28 Mar 2017 12:06:13 -0700

John Levine wrote:
> names if and when they're defined.

i'm fine with an inventory and a how-to. you're not disagreeing with
what i intended to say.

> ...  It's not offering advice that

as you wrote above, it's also saying "how to add new names". i'd like
our advice in this regard to be considered excellent.

-- 
P Vixie

---

From: Dave Crocker <[email-masked]>
Date: Tue, 28 Mar 2017 14:13:16 -0500

> two underscores in the next design, whose use will be better policed.

Hmmm.  So, I missed that you were targeting the narrower issue of SRV, 
per se, rather than the broader (and shallower) task of attrleaf.

With respect to domain naming -- as opposed to SRV RR details -- the SRV 
spec is more of a template meta-spec -- guidance for later, specific 
specs -- than a detailed spec itself.

As such, one can easily mandate defining a modified template for new SRV 
definitions, going forward.

As John suggests, I think this is independent of the attrleaf task and 
doesn't affect it.

d/

---

From: "John R Levine" <[email-masked]>
Date: 28 Mar 2017 14:25:40 -0500

> our advice in this regard to be considered excellent.

It's only providing the mechanics to add a name to the registry, same as 
is in every other RFC that defines a registry.  It's not policy advice on 
using them in protocols.  If you want to write Underscore Prefixes 
Considered Harmful, that's fine, but it's a different document.

R's,
John

---

From: Paul Vixie <[email-masked]>
Date: Tue, 28 Mar 2017 12:34:07 -0700

> per se, rather than the broader (and shallower) task of attrleaf.

no, i wasn't. i'd like any new SRV-like protocol to learn from SRV's
mistakes rather than following in SRV's footsteps. i don't propose to
alter where new SRV protocols/services should have their rendezvous'.

-- 
P Vixie

---

From: Paul Vixie <[email-masked]>
Date: Tue, 28 Mar 2017 12:37:19 -0700

John R Levine wrote:
> is in every other RFC that defines a registry.  It's not policy advice
> on using them in protocols.  If you want to write Underscore Prefixes

we're dancing on the heads of pins here.

if someone wants a new _ name entered into a registry, and if they plan
to use it in a way that creates a sub-hierarchy, they should be advised
not to follow SRV's example, and in my opinion, the example that ought
to be set for them would be what SRV (and DS) ought to have done, as
described up-thread.

to describe a registry and its mechanics for _ names, without showing
some example of how they would be used or why a reserved name is
important for rendezvous purposes, would be a quarter-step.

-- 
P Vixie

---

From: Dave Crocker <[email-masked]>
Date: Tue, 28 Mar 2017 15:39:15 -0500

> to be set for them would be what SRV (and DS) ought to have done, as

If there were an Information RFC providing such guidance, I could 
imagine a helpful reference to it being provided in a document like 
attrleaf...

d/