Re: [Users] branch parameter in ACK set to zero? - sr-users

31 May 2007

Hi Tim,

As I suspected, it is empty branch is triggered by a bogus SIP flow. The 
ACK generated by the caller device is bogus as the TO uri is different 
than the TO in INVITE.
Also the caller device does use branch at all in VIA and forces openser 
to do pre-RFC3261 transaction matching with involves the TO uri.
As the log show, the ACK does not match any transaction:
    DEBUG: t_lookup_request: start searching: hash=11223, isACK=1
    DEBUG: proceeding to pre-RFC3261 transaction matching
    DEBUG: t_lookup_request: no transaction found

So, the ACK is forwarded as stateless request - for this case, there is 
complicated alg for computing the branch param based on the branch 
params from the previous VIA headers. But the previous VIA is bogus (no 
branch at all) and openser finds itself in the impossibility to compute 
a branch for its VIA.

regards,
bogdan

Tim Madorma wrote:
...
  Hi Bogdan,

 Attached is the log and the openser.cfg file.

 thanks,
 Tim

 On 5/30/07, Tim Madorma &lt;tmadorma(a)gmail.com&gt; wrote:
> Hi Bogdan,
>
> I have attached an html file that shows the call trace (note that the
> OpenSER is 65.185.232.62:5061in the flow). I will send the log file
> and openser.cfg in a separate email since it would put me over the 40K
> limit.
>
> thanks,
> Tim
>
> On 5/30/07, Bogdan-Andrei Iancu &lt;bogdan(a)voice-system.ro&gt; wrote:
> > Hi Tim,
> >
> > the VIA branch param must not be 0, indeed. Could you provide an 
> network
> > trace for the entire call and the debug log for level 9?
> >
> > regards,
> > bogdan
> >
> > Tim Madorma wrote:
> > > Hi,
> > >
> > > In testing with OpenSER 1.2 I noticed that the branch parameter 
> of the
> > > Via in the ACK to 200 OK has a value of zero. This does not seem
> > > right. From 16.6 of RFC-3261:
> > >
> > >         The proxy MUST insert a Via header field value into the copy
> > >         before the existing Via header field values.  The 
> construction
> > >         of this value follows the same guidelines of Section 
> 8.1.1.7.
> > >         This implies that the proxy will compute its own branch
> > >         parameter, which will be globally unique for that branch, 
> and
> > >         contain the requisite magic cookie.
> > >
> > > Please advise.
> > >
> > > thanks,
> > > Tim
> > >
> > > _______________________________________________
> > > Users mailing list
> > > Users(a)openser.org
> > > http://openser.org/cgi-bin/mailman/listinfo/users
> > >
> >
> >
>
> 