Subject: Re: [spfbis] #22: RFC 4408: Section 2.5.7 PermError on invalid domains after macro expansion

From: Arthur Thisell <[email-masked]>
Date: Thu, 30 Aug 2012 06:38:30 -0700 (PDT)

I don't see a problem with some malformed domain names being turned into permerrors, but we need to be careful not to stomp on Section 8 which says, in part: 
   
   When the result of macro expansion is used in a domain name query, if
   the expanded domain name exceeds 253 characters (the maximum length
   of a domain name), the left side is truncated to fit, by removing
   successive domain labels (and their following dots) until the total
   length does not exceed 253 characters.

Some malformed domain names are also covered in section 4.3:

   If the <domain> is malformed (e.g. label longer than 63 characters,
   zero-length label not at the end, etc.) or is not a fully qualified
   domain name, or if the DNS lookup returns "domain does not exist"
   (RCODE 3), check_host() immediately returns the result "none".

So, I guess that means that null labels and labels longer than 63 octets should be permerrors?

---

From: Scott Kitterman <[email-masked]>
Date: Thu, 30 Aug 2012 09:58:42 -0500

Arthur Thisell <[email-masked]> wrote:

>I don't see a problem with some malformed domain names being turned
>into permerrors, but we need to be careful not to stomp on Section 8
>which says, in part: 
>   

I think it makes sense.

Scott K