[dnssd] SRP Update - removing individual services (draft-ietf-dnssd-srp-06)

[Abtin Keshavarzian <[e-mail]>]

Hi all,

Would like to summarize some questions/discussions we had on an email
exchange (with Ted, Kangping, Jonathan, and Rongli) related to SRP and the
process for removing individual service(s).

First a quick (personal) note, I have been reading the RSP spec recently. I
think it is a very well-written and easy-to-read/follow. So I want to give
thanks and kudos to guys who were involved (Ted, Stuart, others).

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There may be use-cases where we want to remove a previously
added/registered service. The question is how to realize this.

I think this can be done by sending two SRP Update message:
- First one removing all services/host-info (with lease time zero)
- Followed by another SR Update re-adding services (excluding the ones
removed) and host-info

However, it'd be good if this can be done more efficiently with a single
SRP update message.

- Currently SRP considers the message to be valid if it includes zero or
more Service Discovery and Descriptions, and exactly one Host Description.
- The idea is to extend spec to allow Update msg to include Service
Discovery/Description (without Host Description) with lease time zero to
use for removing services.
- The update message needs to include the key RR and be signed.
- The server would accept the removal of service only if the key matches
the previously registered key associated with the host and the service, and
if the signature is valid.

Thoughts?

Abtin.