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

[Iñaki Baz Castillo <[e-mail]>]

2011/12/5 Gilad Shaham <[e-mail]>:
>> Yes, using localhost would be another option, but it has a drawback in
>> case the WebSocket SIP UA does not use GRUU: in that case a remote
>> peer would see "localhost" as the target of of WS UA. If it sends a
>> REFER to a third participant containing "Refer-To:
>> <sip:alice@localhost;transport=ws>" then the third participant would
>> try to open a WS connection to itself. Well, as the draft states, GRUU
>> is required for SIP UA's using WebSocket transport, at least in web
>> browsers.
>>
>> So I'm not sure wheter using "localhost" is better than using
>> "anonymous.invalid". Maybe it is better to use "invalid.domain"?
>>
> So, if we were to have normative text that defines this, it would probably
> explain why localhost or any routable domain name is a bad choice as opposed
> to a non-routable domain. Should a UA be free to choose based on a set of
> rules or are we defining one host part for all? Should it generate parts or
> all of this domain dynamically to assist with matching incoming requests? Is
> one free to use an invalid IP (such as the infamous 0.0.0.0)?

Take into account that when a JavaScript code (running in a web
browser) open a WebSocket connection given a WS URI with domain, the
JavaScript code is not aware of the resulting IP nor the IP family
(IPv4 or IPv6). So IMHO using a IP address in Via/Contact is a bad
idea.

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).


> And most importantly, do others believe this requires normative text or not?

I consider that this should be an informative text, maybe by
suggesting the usage of "invalid.domain" or "any non routable domain".


Regards.

-- 
Iñaki Baz Castillo
<[e-mail]>