Errors-to: owner-drums@CS.UTK.EDU
Message-Id: <199506020938.LAA12390@dale.uninett.no>
From: Harald.T.Alvestrand@uninett.no
To: John Gardiner Myers <jgm+@CMU.EDU>
cc: drums@CS.UTK.EDU
Subject: Re: address syntax
In-reply-to: Your message of "Thu, 01 Jun 1995 16:43:18 EDT." <cjnWNai00WBw89xzUj@andrew.cmu.edu>
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Date: Fri, 02 Jun 1995 11:38:35 +0200
Sender: hta@dale.uninett.no

John,

> I saw one specification for "native" IPv6 addresses which had
> hexadecimal numbers and colons.  The idea of permitting colons inside
> a domain is a complete nonstarter--it breaks existing code for
> dealing with route-addr.

I think you mean that the construct

@[ip:v:6]:user@[ip:v:6]

will be awfully hard to get right?
If the BNF says that [] are quoting the construct, I think it should
not be impossible (but of course it breaks existing heuristic parsers...)

I have the feeling it is awfully hard to actually outlaw anything; we might
have to do words like:

"Any implementation MUST only have destinations / produce source addresses 
that conform to the BNF

  addr = localpart "@" domain

  domain = atomwithdot / "[" addressingconstruct "]"

atomwithdot is taken from DNS spec, RFC whatever, section xyzzy, or
its replacement
addressingconstruct is taken from IPv4 / IPv6 documents
no further restriction is made in this document

HOWEVER, any implementation SHOULD be able to generate TO addresses that
conform to the BNF

   .....awful construct including @source,mid,wherever:Jo\e\."blow\"@
   foo    . \b\a\r . [1234 567] . net.....

because such addresses might be required in order to reach users on
misconfigured and badly behaved systems not conforming to this specification.

A mailer SHOULD NOT attempt to "clean" the address syntax of nonlocal
addresses; such behaviour will often make worse problems than leaving
them alone."


                     Harald A

and badly behaved