Re: [sipcore] New Version Notification for draft-ibc-sipcore-sip-websocket-00 (previously draft-ibc-rtcweb-sip-websocket-00)

[Gilad Shaham <[e-mail]>]

On Mon, Dec 5, 2011 at 4:27 PM, Iñaki Baz Castillo <[e-mail]> wrote:

> 2011/12/5 Gilad Shaham <[e-mail]>:
> >> Assuming that a domain is used, I think that which one to set should
> >> not be normative, for the following reasons:
> >>
> >> 1) If Outbound is being used (and it's a MUST for these kind of SIP
> >> endpoints) the host in Via and Contact does not matter (for
> >> registration or dialogs).
> >>
> >> 2) If GRUU is used, the host in Contact would be a globally routable
> >> URI. If GRUU is not used, then there is no way  at all for SIP REFER
> >> mechanism to work (since a SIP WebSocket client can only be contacted
> >> via the WS connection it has opened with the WS server). So the domain
> >> in Contact does not matter (with GRUU it will always work, without
> >> GRUU it will never work).
> >>
> >>
> > Seems right. So we are saying a UA MAY include an invalid host part in
> the
> > registration Contact header and any request top Via header. The UA MUST
> > support Outbound and SHOULD (or MUST) support GRUU.
> > Actually, there is good reason to consider mandating GRUU for this
> scenario.
> > The reason is that suppose 2 different users named Alice register to 2
> > different AORs. Both Alice users go through the same proxy (named P1)
> that
> > supports websockets and it forwards the requests to the different
> > registrars. When an incoming request to one of the Alices comes in, a
> proxy
> > will forward the request to alice@<invalid host> through P1, but P1
> cannot
> > distinguish the two and they are in fact different users. I also believe
> UAs
> > should be encouraged to compare the instance id of incoming requests.
>
> In the scenario you describe Outbound must take place (the registrar
> can only send incoming requests to the users via their outbound SIP
> EDGE proxy implementing WebSocket transport). So the Path header the
> EDGE proxy adds to the REGISTER includes a flow token (RFC 5626),
> probably in the URI username part.
>
> When the registrar routes an incoming request to a registration
> binding of one of those WS clients, such request will contain a Route
> header with same value as the Path header during registration, and the
> EDGE proxy will associate the flow token in such Route URI to the
> corresponding WebSocket connection. This is, the Outbound EDGE proxy
> does not inspect the request URI for incoming requets, but just the
> Route URI and the Outbound flow token in it.
>
> Right, I ignored that path is there, so it also seems correct that GRUU is
a SHOULD