🚀 go-pugleaf

On 13 Dec 90 17:39:56 GMT, karl_kleinpaste@cis.ohio-state.edu said:

kleinpaste> chip@tct.uucp writes:

chip> 2.  A message passing through your domain on its way to my domain
chip> should be left alone, without ANY modifications to the message AT
chip> ALL except for the envelope.

chip> No site causes problems for other sites by following these rules.
chip> So why shouldn't we all adopt these rules right now?  I'm
chip> listening...

kleinpaste> I doubt it.  Pardon me for being rude, but I really doubt
kleinpaste> it.  A hypothetical example.  Let's assume that "tct" is a
kleinpaste> UUCP neighbor of "osu-cis."  Let's assume that chip@tct.uucp
kleinpaste> sends mail aimed at, say, osu-cis!ucbvax!somebody.  Headers
kleinpaste> read:

kleinpaste> 	From: chip@tct.uucp
kleinpaste> 	To: osu-cis!ucbvax!somebody

kleinpaste> Envelope looks like "From tct!chip" and "rmail
kleinpaste> ucbvax!somebody" by the time it reaches my system.  So far,
kleinpaste> so good, I hope.

No, nothing good. Your hypothetical geek is using two different and
incompatible addressing formats in a message. Is the message intended to
be RFC822 compliant? If so, the "To:" line is not. Is it intended to be
UUCP compliant? If so, anything goes (UUCP mail only cares about the
envelope), but then he guy is not expecting to be replied to for real,
as the From: line is bogus from a UUCP point of view. He would force an
UUCP target to use the 'From ' line to reply. If he used a proper UUCP
relative name such as 'From: seismo!tct' things would be ok instead.

Note: let me repeat that not a lot of people realize that in the UUCP
world addresses and routes are not the same thing; UUCP uses relative
names, that is a site name is given as 'a!b!c' which means 'the c
machine which a neighbour of b, which is a neighbour of a'. Given UUCP
maps one can well devise a completely different route to *that* 'c',
that does not pass thru 'a' or 'b'. This is why 'From: '  and 'From '
(and 'Reply-To: ') in UUCP mail can specify completely different bang
sequences.

kleinpaste> My mail installation wants to do things to reach ucbvax via
kleinpaste> the Internet rather than UUCP.  That is, seeing
kleinpaste> "ucbvax!somebody" as an intended destination, I nonetheless
kleinpaste> want to speak SMTP to ucbvax.berkeley.edu.  This is
kleinpaste> perfectly legit, as the choice of outbound transport is mine
kleinpaste> to make.

Not so easy! First you must prove that ucbvax and ucbvax.berkely.edu are
the same entity. Granted that you do that, you now have the problem of
*you* deciding to become a gateway between the UUCP and the Internet
world. This is *your* problem, as the originator of your piece of mail
cannot possibly anticipate it. As a gateway it is *your* problem to
preserve semantics. You get a patched up solution:

kleinpaste> I generate RFC-compliant headers when speaking to Internet
kleinpaste> sites.  So I will generate the following SMTP conversation
kleinpaste> to ucbvax.berkeley.edu for this mail:

kleinpaste> 	HELO something.cis.ohio-state.edu
kleinpaste> 	MAIL FROM:<tct!chip@cis.ohio-state.edu>
kleinpaste> 	RCPT TO:<somebody@ucbvax.berkeley.edu>
kleinpaste> 	DATA
kleinpaste> 	From: tct!chip@cis.ohio-state.edu
kleinpaste> 	To: ucbvax!somebody@cis.ohio-state.edu
kleinpaste> 	your text
kleinpaste> 	.
kleinpaste> 	QUIT

kleinpaste> That works.  Nothing else does.

I agree it works, *as things are now*, but it is disgusting. The real
problem is that, let me repeat it for the millionth time, the UUCP and
Internet naming structures are totally different, and there is no good
way to map one onto the other in all cases, so a gateway to/from the
Internet cannot guarantee to preserve semantics.

The real solution is not to attempt to do this, like you do above, but
to introduce in the Internet a way of addressing entities outside the
Internet naming structure.

That is, the real problem is simply that the Internet standards do not
provide for mail gateways, so if poor Kleinpaste of Ohio state is good
enough to provide one, he has to pretend that certain things are
Internet addresses, because the Internet is a closed system (as far as
standards make it), when they are not, and this causes endless trouble.

Note that this is pure Internet parochialism; since UUCP uses relative
naming and quasi-source routing, UUCP mail can easily accomodate any
other naming scheme that does not exclamation marks in its addresses.

As fas as I remember, you said that for precisely this reason Ohio's
sendmail translates all addresses internally to UUCP bang notation and
then reconverts them to Internet if necessary at the last moment if
needed. Is is too late to switch the Internet to bang notation, at least
for naming (not for routing)? I am afraid it is. But it is not too late
to add some decent extension to the headers to handle this.

Many will recognize my style when I say that your solution should be
rewritten as:

	HELO something.cis.ohio-state.edu
	MAIL FROM:<uucp-gateway@cis.ohio-state.edu>
	RCPT TO:<somebody@ucbvax.berkeley.edu>
	DATA
	Sender: uucp-gateway@cs.ohio-state.edu
	Apparently-To: somebody@ucbvax.berkeley.edu
	From: chip@tct.uucp
	To: osu-cis!ucbvax!somebody
	your text
	.
	QUIT

Note, note that I am not sure about adding 'Apparently-To: ', a bit more
about 'Sender: '; and note that the 'To: ' is *unchanged*, because it is
not a route (routes belong to envelopes!), it is a relative address. The
'From: ' is also unchanged, of course!

What about a nice RFC that standardizes ways of addressing entities
beyond a gateway between the Internet and the DNS and the
something-that-lurks-malignantly-in-the-dark-night-outside?
--
Piercarlo Grandi                   | ARPA: pcg%uk.ac.aber.cs@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcsun!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk