Re: [Sip] SIPS question

[Christer Holmberg <christer.holmberg@lmf.ericsson.se>]

Hi,

> I agree that I don't see any immediate use for this, but I also don't see
> any danger that would mandate forbidding it. Was there anything you had in
> mind?

Assuming the UAS does insert a SIPS-URI in the Contact, let's have a look at
the following scenario:

UA1 ------------- P1 -------------- UA2

Now, UA1 sends an INVITE to UA2, via P1:

- UA1 inserts a SIP-URI in the Request-URI

- P1 inserts a Record-Route header with a SIP-URI

- UA2 sends 200 with a Contact header with a SIPS-URI


Q1:  Now, UA2 indicates that requests from P1 to UA2 shall be sent using TLS,
due to the SIPS-URI in the Contact. However, requests from UA2 to P1 would be
sent using let's say UDP, due to the SIP-URI in the Record-Route.


Q2: Now, if P1 supports loose routing, when UA1 sends another request within
the session, it will look like:

Request-URI: SIPS-URI: UA2
Route:SIP-URI: P1;lr

Now, according to chapter 26.2.2 in RFC3261, if the Request-URI contains a
SIPS-URI, TLS shall be used. However, the request is not sent to the
Request-URI, but to the top Route, which contains a SIP-URI. So, since P1
record routed with a SIP-URI, and that route is used to route the request, why
shall UA1 make the transport decission based on the SIPS-URI in the
Request-URI??? UA1 doesn't even know if P1 supports TLS or not, and UA1 may
not support TLS, so....


Regards,

Christer Holmberg
Ericsson Finland




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