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From: diamant@hpfclp.HP.COM (John Diamant)
Newsgroups: comp.mail.misc
Subject: Re: address writing by gateways (was: NO NO NO NO NO)
Message-ID: <8120007@hpfclp.HP.COM>
Date: Tue, 21-Jul-87 02:40:57 EDT
Article-I.D.: hpfclp.8120007
Posted: Tue Jul 21 02:40:57 1987
Date-Received: Sat, 25-Jul-87 12:32:23 EDT
References: <715@vixie.UUCP>
Organization: HP, Fort Collins, CO
Lines: 99

Sorry for the late reply, but with net delay and my being out of the
office for a week and a half, these things happen.


>>> = Paul Vixie
>> = John Diamant
> = Paul Vixie again
>
>>>[Paul Vixie wonders why every host in a route-addr needs to be registered. 
>>>Suggests that it may be a political thing, because ARPA dislikes being
>>>used as a transport for non-ARPA mail (that originates and terminates on
>>>non-ARPA hosts).]
>>
[ some discussion about RFC-822 wording omitted]
>
>Still, I agree with your interpretation of RFC-822 in this respect.  I guess
>this IS a valid reason to use %@ instead of <@,:@>.  But it seems like a
>gratuitous restriction, for the reason I stated above.

I agree.  My understanding of the reason for the restriction was that the
author of the RFC wanted to actively discourage use of source routes and
expected them to be almost totally unnecessary.  This hasn't happened yet,
but because of his restrictions, they aren't very useful.
>
>The only routing syntax available in
>the SMTP world is %@, apparently; if there is no standard that specifies "%",
>then routes cannot be rewritten between UUCP- and SMTP-based networks, and
>gateways between them will necessarily not be perfect.

A catch-22!
>
>>Also, if a "%" came in and was translated to
>>"!" and then left again, but was now as source route, then you've illegally
>>applied an interpretation to it.
>
>The envelope address in the UUCP network should always have a pure !-route in
>it (if it doesn't, then is still SHOULD :-)).  When a gateway host gets a
>message from its UUCP side, and detects that it needs to be forwarded to an
>SMTP network, it can rewrite the envelope address as much as it wants to do.
>The header address may be in normal, domain form, in which case it should be
>left alone so that replies can use a new (and perhaps better) source route; if
>the header addresses are in !-form, well, they aren't protected by RFC-822
>(the whole thing would be a local part), and can be re-written into the
>routing syntax of the new network (SMTP, in this case).

Agreed.  It is SMTP -> UUCP where the problem occurs, I think.  Regarding your
comment about local part, I would say that is only true if it wasn't an RFC976
style address that was translated at an SMTP -> UUCP gateway already.
>
>The fact that SMTP doesn't have a routing syntax (route-addrs need registered
>hosts only, and % is non-standard) stops this scheme in its tracks.  Can we
>bend or push either of those restrictions?

I think there really is nothing forcing the source routing requiring
registered domains except for the wording of RFC822.  I don't think there
is anything fundamental that would break if that were ignored.  But realize
that this requires a new RFC obsoleting RFC822 and explicitly allowing this
before consistent acceptance of this could be obtained.  See my comments
above for an explanation of why the restriction came about (at least what
I've heard).

The problem with the % non-standard handling is that RFC976 hosts could be
required to handle precedence as follows: "@", "!", anything else ("%"), but
RFC822 hosts could not be expected to take "!" over "%."
>
>>I gave it a shot.  What do you think now?  This situation is deceptive.
>>Scott McGregor (also of HP) and I tried to write an RFC to clarify this
>>problem and we discovered the deeper we got, the more complicated the
>>RFC got, and the worse the problem became.
>
>I think you're right about % being insufficient, and you seem to be right 
>about <@,:@> being insufficient, and I'm not sure what to suggest.  Maybe
>we can remove the registration restriction on route-addrs -- as I stated
>way up there, it doesn't seem to be necessary (and it certainly isn't
>helpful in this case!).  Alternatively, an RFC that specified "%"/"@"/"!"
>and their relationship to eachother would make "perfect" UUCP/SMTP gateways
>possible.  You can send me your unfinished RFC, if you think it will
>enlighten me...

When I find my most recent copy, I will send it by email.  I don't think
it is appropriate for wide distribution as it has several problems (that's
why we stopped working on it -- we didn't seem to be getting closer to a
solution).  I'm not sure if it will help clarify things for you or confuse
them more.  However, I am coming into this discussion already having attempted
to hash this out once before unsuccessfully (the attempted RFC) and am
not overly confident.
>-- 
>Paul A. Vixie, Esq.		   "A viler evil than to throw a man into a
>paul%vixie@uunet.uu.net		    sacrificial furnace, is to demand that he
>{uunet,ptsfa,hoptoad}!vixie!paul    leap in, of his own free will, and that he
>San Francisco, (415) 647-7023	    build the furnace, besides."  (Ayn Rand)
>----------
					Good quote ^


John Diamant
TSBU				UUCP:  {hplabs,hpfcla}!hpfclp!diamant
Hewlett Packard Co.		ARPA Internet: diamant%hpfclp@hplabs.HP.COM
Fort Collins, CO