Iñaki Baz Castillo wrote:
> Hi,
>
> It's very common that when a UA1 sends a REGISTER via TCP from a random port
> 11111, if the connection remains open (for example using ping-pong method),
> the proxy can send request to UA1 using that TCP connection.
> Is really this behaviour defined in RFC 3261?
>
> There is other case: imagine UA1 sending a TCP INVITE to a UA2, so UA1
> creates
> a new TCP connection from random port 22222. This TCP connection would
> persist just for a few time (the time needed for the INVITE transaction =
> 64*T1), but which should be UA1 behaviour if it receives a new incoming
> request via this port 22222?
> I expect this request should be dropped, am I right? but I really wonder
> which
> is the difference between this case and the above case in which UA1 receives
> incoming requests from the proxy using the port 11111 used for registration.
>
> Note: I don't consider the draf-outbound, neither the draft about TCP
> connection reuse.
You say you don't consider the connection reuse draft. But you should,
because its intent is to clarify behavior that is unclear in 3261.
Your second case is excluded by the connection reuse draft. Its unsafe,
because in general you have no way to verify that the source corresponds
to the contact.
Your first case seems inappropriate because the register request in
general does not require that the source be coincident with the contact
that is registered. In fact, its quite legal to register multiple
contacts that have distinct addresses. (I say "in general" because
certain extensions require the contact to belong to the sender. In
particular, sip-outbound and gruu require this.)
Thanks,
Paul
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