Path: utzoo!attcan!uunet!jetson!john
From: john@jetson.UPMA.MD.US (John Owens)
Newsgroups: comp.mail.uucp
Subject: pathalias: terminal nodes and domain gateways
Message-ID: <114@jetson.UPMA.MD.US>
Date: 23 Aug 88 21:16:25 GMT
Organization: SMART HOUSE Limited Partnership
Lines: 91

I've run into an interesting anomaly between pathalias and smail (and
possibly other pathalias-using routers).  First, let me illustrate
with a couple of pathalias runs:

% cat one
me	gateway(1)
me	him(100)
him	gateway(100)
gateway = domain.org
gateway	.domain.org
% pathalias -l me < one
me	%s
him	him!%s
gateway	gateway!%s
.domain.org	gateway!%s
domain.org	gateway!%s
% cat two
me	<gateway>(1)
me	him(100)
him	gateway(100)
gateway = domain.org
gateway	.domain.org
% pathalias -l me < two
me	%s
him	him!%s
.domain.org	him!gateway!%s
gateway	gateway!%s
domain.org	gateway!%s

Note that declaring the me -> gateway link as terminal causes the
path to .gateway.org to take the higher-cost link, which is exactly
what pathalias should do.

When smail decides to route to user@domain.org, it checks for routes in
the following order:
	.domain.org
	domain.org
	.org
	org
	smart-host (if defined to)

In the first two cases, it uses route!user; in the remainder, it uses
route!domain.org!user.

Now an actual example, showing why I think there's a problem.

uunet declares
	uunet	<rutgers>(DEDICATED)
rutgers says
	rutgers = rutgers.edu
	rutgers .rutgers.edu
The pathalias output for my site contains
.rutgers.edu	long!path!to!rutgers!%s
rutgers.edu	uunet!rutgers!%s

Ok so far.

Now, when smail sees mail for user@rutgers.edu, it uses
long!path!to!rutgers!user, instead of uunet!rutgers!user.

I think the lookup process for user@domain.org should first check for
an exact match for domain.org, and if found, replace the %s with
"user".  Otherwise, it should check for domain gateways (*only those
beginning with a dot*), starting with .domain.org and working down,
and if found, replace the %s with "domain.org!user".

In other words, it should only look for
	domain.org			(giving route!user)
	.domain.org			(giving route!domain.org!user)
	.org				(giving route!domain.org!user)
	smart-host			(giving route!domain.org!user)
when routing user@domain.org and for
	sub.domain.org			(route!user)
	.sub.domain.org			(route!sub.domain.org!user)
	.domain.org			(route!sub.domain.org!user)
	.org				(route!sub.domain.org!user)
	smart-host			(route!sub.domain.org!user)
for user@sub.domain.org.

This would cause mail for user@rutgers.edu to take uunet!rutgers!user,
but mail for user@foobar.rutgers.edu to take
long!path!to!rutgers!foobar.rutgers.edu!user, which is as it should be.

I'd appreciate comments on this.  What's the state of smail 3.0?
What other pathalias-using routers do this?  Do any do it the way I
suggested above?

-- 
John Owens		john@jetson.UPMA.MD.US
SMART HOUSE L.P.	uunet!jetson!john		(old uucp)
+1 301 249 6000		john%jetson.uucp@uunet.uu.net	(old internet)