Re: A 30% solution

On 5/11/04 at 9:48 PM -0500, wayne wrote:

> In the last jabber session I suggested using SPF or DMP as something 
> to use so that we could all be on the same page about what exactly 
> is meant by "semantics" vs "data" vs "identities", etc.
My concern (and I suppose that of others) is that by looking at a 
proposal that already had a solid syntax, we'd end up conflating the 
syntax and semantics in unproductive ways during the discussion.
> > The MARID records will contain entries that (when fully resolved) 
> > will give the receiver two sets of IP addresses,
> Two points:
>
> 1) SPF creates a set for "DNS errors" to deal with situations when 
> something can not be fully resolved due to a temporary name server 
> problem.  I think this is an important set and should be kept.
> 2) You actually describe three sets.  The third being the set of IP 
> addresses that are not known to be legitimate or illegitimate.
Actually, there is no third set in my model. What you get back is 
either legitimate or illegitimate addresses. You never get back 
addresses from the DNS which are marked "not known". It is only the 
failure to find the client SMTP address in either the legitimate or 
illegitimate sets that makes it "not known".
Because of that, I'm not sure that the "DNS error" set makes sense: 
Failure to get back an address is failure to get back an address, 
whether due to exhausting the records, or due to a temporary DNS 
failure. However, a DNS failure might say something about the ability 
to cache certain information; that's an interesting discussion point.
> > * The records
> Would you envision the "MARID records" to be a RR set, or single RR 
> from the DNS point of view, but containing multiple "MARID records"?
As I think you already suspected, I was thinking in terms of multiple 
RR's returned.
> This is not just a syntactical issue.  You can't depend on the order 
> of the records in a RR set
Really? As I understood, many systems depend on getting records back 
in a particular order for round-robin applications. Or do you mean 
that there is simply not a *guaranteed* order because UDP packets 
might arrive out of order?
> What happens if an IP address is in more than on set?  Would a MARID 
> client need to process all MARID records in order to determine the 
> outcome, or can you short-circuit the checks?
I think it would be reasonable to say that an IP address appearing as 
both legitimate and illegitimate is a "configuration error" for all 
intents and purposes, and short-circuiting is a reasonable 
optimization.
[...tracking...]
> Can we add this kind of tracing/debugging tool to a pure set notation system?
There can likely be the "obvious" tracking, but since there is way in 
my semantics to get the IP address that you are searching for into a 
query (like you can with the "i" macro in SPF), you can't do the more 
elaborate tracking that you may be looking for. Personally, though I 
think it's a nifty feature, I don't think it's necessary.
pr
--
Pete Resnick <http://www.qualcomm.com/~presnick/>
QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102