Re: [dmarc-ietf] 5.5.4. Publish a DMARC Policy for the Author Domain - dmarcbis-06

[Scott Kitterman <[e-mail]>]

On Tuesday, April 5, 2022 4:43:49 AM EDT Alessandro Vesely wrote:
> On Mon 04/Apr/2022 15:29:40 +0200 Scott Kitterman wrote:
> > The diff is relative the last text I posted.
> 
> Section 5 has to stay before Section 4.  It makes no sense to exemplify
> _dmarc.example.com if we haven't yet said that:
> 
>     Domain Owner and PSO DMARC preferences are stored as DNS TXT records
>     in subdomains named "_dmarc".
>                                                    [Current Section 5.1]
> 
> 
> Then, let's make a statement like so:
> 
>     Retrieving the DMARC record of a domain implies the following steps:
> 
>     1.  Prepend the label "_dmarc" to the domain name and issue a DNS Query
> for a TXT record at the resulting domain.  For example, if the domain is
> example.com, query _dmarc.example.com.
> 
>     2.  Collate any string returned, in the order returned.
> 
>     3.  Records that do not start with a "v=" tag that identifies the
>         current version of DMARC are discarded.  If multiple DMARC
>         records are returned, they are all discarded.
> 
> 
> At this point, the algorithm can be expressed in a shorter form like so:
> 
>     1.  Set the current target to the identifier at hand, which is one of
> the domain(s) described above.
> 
>     2.  Retrieve the DMARC record of the current target.
> 
>     3.  If the record exists and contains either psd=y or psd=n, stop.
> 
>     4.  Break the current target name into a set of "n" ordered
>         labels.  Number these labels from right to left; e.g., for
>         "a.mail.example.com", "com" would be label 1, "example" would be
>         label 2, "mail.example.com" would be label 3, and so forth.
> 
>     5.  Count the number of labels in the current target.  Let that number
>         be "x".  If x = 1, stop.  If x < 5, remove the left-most (highest-
>         numbered) label from the subject domain.  If x >= 5, remove the
>         left-most (highest-numbered) labels from the subject domain until
>         4 labels remain.  The resulting DNS domain name is the new target
>         for subsequent lookups.
> 
>     6.  Go to 2.
> 
> 
> Better?

Maybe.  I'd say lets get a draft out that we agree gives the correct result 
before we start re-writing for taste.  I don't think the order matters that 
much.  An RFC is not a single pass compiler.

Scott K