Re: Comments on draft-freed-sieve-environment-04

[Ned Freed <[e-mail]>]

> On Tue, 2008-03-25 at 09:52 -0700, Ned Freed wrote:
> > > On Sun, 2008-03-23 at 10:50 -0700, Ned Freed wrote:
> > > > Also a good point. I have added:
> > > >
> > > >   The remote-host environment item defined in this specification is usually
> > > >   determined by performing a PTR DNS lookup on the client IP address. This
> > > >   information may come from an untrusted source. For example, the test:
> [...]
> > > sorry, I don't understand what this means.  is the existence of a PTR
> > > record sufficient?
> >
> > Who knows? The mechanism used to obtian the remote-host isn't (and should not
> > be) specified. As such, a PTR could be sufficient. Or it may not be - some
> > systems do a backwards-forwards check. And there can even be cases when a PTR
> > record isn't needed - DNS names aren't the only game in town, you know.

> ok.  I think it could be made a little clearer, though.  how about:

>         How to determine the remote-host environment item defined in
>         this specification is left up to the implementation, e.g, if TLS
>         is in use, the remote system's name can be extracted from the
>         client certificate if the signer is trusted.  Probably more
>         commonly it will be determined by performing a PTR DNS lookup on
>         the client IP address.  This information may come from an
>         untrusted source.  For example, the test:

I really don't want to get into the whole TLS cert thing in this document.

> another alternative, with no specific details about alternatives:

>         An implementation can use any technique to determine the
>         remote-host environment item defined in this specification, and
>         the trustworthiness of the result will vary.  One common method
>         will be to perform a PTR DNS lookup on the client IP address.
>         This information may come from an untrusted source.  For
>         example, the test:

This, OTOH, is fine. I'll include it in the next revision.

				Ned