[sr-dev] LCR: defunct_gw() is dangerous

[Iñaki Baz Castillo]

2011/12/28 Juha Heinanen <jh at tutpro.com>:
> Iñaki Baz Castillo writes:
>
>> If the Via header is invalid, then the Proxy/UAS *cannot* reply to the
>> request, or not in every cases. Theorically the Proxy/UAS replies to a
>> request based on the information in Via header.
>
> since via header was added by your sip proxy, it is valid and the uas
> should be able to respond to the request.  if it is does not, show me
> where is rfc3261 it is written and uas does not need to respond to such
> a request.

You are assuming that:

- There is a proxy between the UAC and the UAS (GW).
- The proxy does not route the request to another proxy.
- The UAS just inspects the top most Via.
- The proxy does not inspect the top Via added by the UAC (if not it
could reject the request).

First of all, a proxy could inspect ALL the Via headers, for example
in order to detect spirals or loops as RFC 5393 states.

Anyhow, we are not discussing about that. Tomorrow I will paste the
malformed SIP request that Kamailio forwards to the GW.

Cheers.

-- 
Iñaki Baz Castillo
<ibc at aliax.net>