Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!giza.cis.ohio-state.edu!karl From: karl@giza.cis.ohio-state.edu (Karl Kleinpaste) Newsgroups: comp.mail.misc Subject: Re: sigh (was Re: Short-circuiting a route) Message-ID: Date: 14 Jul 89 18:58:52 GMT References: <562@daitc.daitc.mil> <12167@polyslo.CalPoly.EDU> <1888@prune.bbn.com> <423@cwjcc.CWRU.Edu> <425@cwjcc.CWRU.Edu> Sender: news@tut.cis.ohio-state.edu Organization: Ohio State Computer Science Lines: 47 In-reply-to: edguer@charlie.CES.CWRU.Edu's message of 14 Jul 89 15:57:39 GMT edguer@charlie.ces.cwru.edu writes: > According to RFC822, you are correct. According to RFC822 however, > there is no such thing as a "!" path. True, but there is such a thing as a "local part," with which I am free to do as I please, including a rewrite into @-format. > Bang paths do qualify in my opinion because of RFC976. RFC976 says > that a gateway should change an RFC822 source route into an RFC976 > bang path when sending to the next hop via UUCP. This means that > if you receive a bang path via UUCP you may be receiving a valid > RFC822 source route from another site that is following the rules. > This is why I feel that to properly comply with the mail RFC's you > should treat ALL bang paths as valid source routes. No active rerouting. I see what you're getting at; the point is well taken. But I think there are problems with the interpretation of it. Passive rerouting, when the first specified host in the path is unknown, is a violation of the source-route rules as much as active rerouting. If we're going to attach strict source route rules to !-paths, then we have to obey those rules. Those rules say that, if you give me <@a.b,@c.d,@e.f:u@g.h> then I must hand the mail _directly_ to a.b. It doesn't say that I may find my own best intermediate-hop route to a.b; it says I have to go straight there. On the Internet, this is fine, since one assumes complete interconnectivity. I can't do that in the Land of UUCP, in general. An indirect proof for everyone... [1] Condition: "!-paths" are to be equated with "source routes." [2] Conclusion: Interpretation of source routes according to the RFCs requires that a relay host send directly to the first routed host specified in the source route. [3] In UUCP, a relay host cannot, in general, be counted on to be connected to the first such host. [4] Therefore, the conclusion is false, so the condition must also be false. My, I can feel it getting warmer in here already... --Karl