Subject: Subject: Re: #1047 permitted constructs - a list

From: John Stanley <[email-masked]>
Date: Wed, 15 Feb 2006 15:01:04 -0800 (PST)

Harald Tveit Alvestrand <harald@xxxxxxxxxxxxx>:

>Can you point me at your poll opinion? Didn't see it in the list archives
>when I scanned them...

Re: #1047 POLL: Path-diagnostics
http://www.imc.org/ietf-usefor/mail-archive/msg02801.html

>> But just what IS a path-diagnostic anyway?

> It's not an identity, and most of the WG wants it in the path.

What it is NOT is not a definition. "Wants it in the path" resulting it
it BEING in the path ought to depend on it having some defined meaning,
not just a desire to have something in the path that has no definition.

The only "definition" we have is that it is "something in the path that
isn't a server that article has passed through", or something to that
effect. And yet, the only reason it exists as a separate item is so that
colons can be made legal in an IPv6 that records -- a server that the
article has passed through.

If nobody can define it in any terms other than "it isn't" one of the
things that it actually IS, then it does not merit inclusion in a
standard.

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Thu, 16 Feb 2006 09:47:05 +0100

> http://www.imc.org/ietf-usefor/mail-archive/msg02801.html

Thanks, and my apologies - don't understand why I missed it.

> article has passed through.

I don't see that as a reason. The decision of the WG to put stuff in the 
path that wasn't "servers the article has passed through" seems to have 
been taken a very long time before I joined the WG, and long before there 
was anything near consensus on the format of IPv6 addresses.

> things that it actually IS, then it does not merit inclusion in a

Do you want to call for a poll for "remove anything that isn't a 
path-identity from the path"?

                       Harald

---

From: "Charles Lindsey" <[email-masked]>
Date: Thu, 16 Feb 2006 11:22:30 GMT

>article has passed through.

A reasonable definition would be that it is "something in the path that
isn't a server that article has passed through, and which was added by
some relayer as an aid to diagnosing problems that might arise (for
example attempts to disguise the source of an article)."

It will be up to USEPRO to define which diagnostics may be used, and how
(or else we hardcode the allowable ones into USEFOR, though I am coming
more and more to the belief that USEFOR should just establish the
framework and let USEPOR specify the gory details, as indeed it currently
does, though not with the currently proposed notations).

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
Email: [email-masked]      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5

---

From: John Stanley <[email-masked]>
Date: Thu, 16 Feb 2006 13:53:49 -0800 (PST)

On Thu, 16 Feb 2006, Harald Tveit Alvestrand wrote:

> I don't see that as a reason. The decision of the WG to put stuff in the path 
> that wasn't "servers the article has passed through" seems to have been taken 
> a very long time before I joined the WG, and long before there was anything 
> near consensus on the format of IPv6 addresses.

That's true, but the REASON that it is now a "diagnostic" and not just a
path-identity is so that "we" could prohibit colons in path-identities and
still keep IPv6 addresses with their colons. For many years, people have
been able to put this stuff in the header field without a special name
for it.

> path-identity from the path"?

I want it to either have a definition that is meaningful AND correct or 
get rid of it. Either way. This "it's not ..." is meaningless, especially 
since one known use is to record the identity of a site that the message 
has passed through.

---

From: "Charles Lindsey" <[email-masked]>
Date: Fri, 17 Feb 2006 11:14:14 GMT

>been able to put this stuff in the header field without a special name

No, that is not the reason. Originally (in the days of Brad Templeton) a
diagnostic was indicated by assorted special delimiters. Then we changed
to keywords with assorted forms of syntax. And finally, we have settled
for diagnostics always starting with a "." (except for the special case of
"!!" which is really a shorthand for ".MATCH.the.identity.already.present").

As a separate issue, we seek to avoid the use of colons so far as
possible. We don't allow IP addresses as identities, but we still allow
them in diagnostics, and hence we restrict colons to IPv6 addresses in
diagnostics.

And as a further issue, the consensus seems to be that if IPv6 addresses
are to occur at all, then we will use the commonly accepted notation for
them, rather than inventing somethbng new.

As a result of all that, we can now safely say that the only barewords
which might be troublesome are those composed of four or less hexadecimal
digits, and that is considered an acceptable risk.

>since one known use is to record the identity of a site that the message 

It would perhaps be useful to include an explanation of the purpose of
diagnostics in USEFOR perhaps using a tidied up version of what I wrote
yesterday.