Re: [Exim] Exim 4.02 new "feature"

On 2002-03-27 at 11:03 -0800, John W Baxter wrote:
> Yikes. If we take that (including the referenced material) at face value,
> BIND 9 will serve a name containing an ASCII NUL character (0x00).

It should do, if it conforms, yes.

DNS is pseudo-binary. Not quite binary, since ASCII alphabetic
characters are compared case-insensitively. But otherwise ...

> I have a feeling that such names aren't a good idea for our purposes.

Yes. Nor are a lot of other things. If I haven't already said this on
exim-users@, then this is one of the few places to escape unscathed.
;^) Using " . " to separate labels, instead of the usual ".", this is a
perfectly valid DNS entry:

www . foo.bar . example . org .

Could be some problems if you convert DNS into a concatenated string
representation, then try to convert back, and didn't use an escaping
convention.

Answer: don't convert unless you need to. :^) So be careful how you
compare your data when matching forward and reverse lookups.

> The section does continue on to say that clients of the DNS can impose
> naming restrictions appropriate to their needs. As the mail RFCs attempt
> to (with little success regarding _).

The mail RFCs do so, pretty well. They only 'fail' on underscore,
because fools who don't read documentation configure stuff which doesn't
have adequate checks for use by fools, and then expect it to work on the
Internet.

The question becomes "how much else are they screwing up"?
--
Sarcasm is just one more service we offer.