Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!hpfcdc!hpfclp!diamant
From: diamant@hpfclp.SDE.HP.COM (John Diamant)
Newsgroups: comp.mail.sendmail
Subject: Re: Re: sendmail parsing questions: "%"
Message-ID: <1410012@hpfclp.SDE.HP.COM>
Date: 26 Apr 89 02:21:28 GMT
References: <27172@cornell.UUCP>
Organization: HP SESD, Fort Collins, CO
Lines: 29

> To make a concrete example, given an address like:
> 
> 			a!b%c@d
> 	
> 	1)	-> host a -> host d -> host c -> user b.
> 	2)	-> host d -> host a -> host c -> user b.
> 	3)	-> host d -> host c -> host a -> user b.

If all hosts are RFC976 compliant, the answer is 2.  This is because all
defined routing characters must take precedence over any character that is 
not defined by the standard.  "@" and "!" are defined, and "%" is not; thus,
"%" must be lower than "@" and "!."  So far, so good.  The real problem comes
about that only one of the hosts is actually a gateway between internet
and UUCP and thus is required to be RFC976 compliant.  Choice 1 above is
illegal, because a is acting as a gateway between UUCP and Internet and it
is not complying to RFC976.  The problem is distinguishing between 2 and 3.
If d is not in fact a UUCP gateway, then it isn't required to be 976
compliant, and it may thus give "%" precedence over "!" (not even knowing
what "!" is).  In this case, you'd get choice 3.

So, in a nutshell, if everyone could be guaranteed to be 976 complaint,
then the answer is unambiguously 2.  Otherwise (as the real world is), it is
ambiguous between 2 and 3.


John Diamant
Software Engineering Systems Division
Hewlett-Packard Co.		ARPA Internet: diamant@hpfclp.sde.hp.com
Fort Collins, CO		UUCP:  {hplabs,hpfcla}!hpfclp!diamant