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Re: Strict RFC x821 Compliant: HELO/EHLO

2005-07-03 11:11:05

From: "Claus Assmann" <ietf-smtp(_at_)esmtp(_dot_)org>

Ok, let's try this again: The statement was:

"This would be an illegal syntax per the ABNF:"

This statement is wrong. The parameter is _syntactically_ valid (as
I pointed out before by quoting the grammar).  Maybe it would be
useful to change the syntax to reflect that "the highest-level
component label will be alphabetic.".

Oh, I see your point.

The ABNF is:

      address-literal = "[" IPv4-address-literal /
                            IPv6-address-literal /
                            General-address-literal "]"

Section 4.1.3 Address Literals specifically defines the format for each of
the above.  For the sake of simplicity, using IPv4:

      IPv4-address-literal = Snum 3("." Snum)
      Snum = 1*3DIGIT  ; representing a decimal integer
            ; value in the range 0 through 255

This defines an alphanumeric dotted string format.

But 2821 does not specifically define or say the address-literal could not
be a A record in DNS.

I see your point... however.

As long as that isn't the
case, the command above is correct according to the grammar given
in RFC 2821 (that's why my software doesn't reject it in contrast
to the _syntactically_ invalid MAIL command that triggered this
HELO/EHLO discussion).

You are technically correct per 2821, but 2821 *UPDATES* 1123, hence 2821
overrides various parts in 1123, but other items in 1123 not updated by 2821
still take hold.

So 1123 covers the definition of what is considered a valid TLD based domain
vs. a dotted-address format.

Remember, 1123 came first before 2821 so you will find systems following its
guidelines as well.

Hector Santos, Santronics Software, Inc.