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raybellis / draft-bellis-dnsop-xpf

DNS X-Proxied-For
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Update "EDNS Option Format" section to use ECS-inspired "FAMILY" field #1

Closed edmonds closed 7 years ago

edmonds commented 7 years ago

Hi, Ray:

Please consider borrowing the FAMILY field from the EDNS client subnet option. This PR borrows some language from RFC 7871.

The Address_Family_Numbers reference is:

[Address_Family_Numbers]
           IANA, "Address Family Numbers",
           <http://www.iana.org/assignments/address-family-numbers>.

(Not entirely sure how to add a reference using this document format.)

Thanks!

raybellis commented 7 years ago

On writing this up I did consider using the ethertype field (e.g. 0x0800 for IPv4, 0x86dd for IPv6) but my conclusion was that since things like ACLs etc are only ever implemented in terms of IP address, there was no point using a field that represents non-IP protocols.

I didn't know that ECS used this, and if I had spotted it (i.e. been paying that much attention to a "bad idea" draft) I would've objected to it...

raybellis commented 7 years ago

I note that RFC 7871 only defines this field as valid for 2 of the possible values anyway, i.e. those for IPv4 and IPv6. I don't think the code re-use opportunities merit making this change.

edmonds commented 7 years ago

OK, fair enough, there are only so many ways to specify an enum with two values.

This does make the option IN class-specific, I guess :-)

raybellis commented 7 years ago

EDNS OPT RRs have no class - that field is used for the UDP payload size instead ;)