-----Original Message-----
From: Andrei Pelinescu-Onciul
[mailto:pelinescu-onciul@fokus.fraunhofer.de]
Sent: Tuesday, October 26, 2004 1:58 PM
To: Martin Koenig
Cc: serusers(a)lists.iptel.org
Subject: Re: [Serusers] Loose Route
On Oct 25, 2004 at 15:39, Martin Koenig
<martin.koenig(a)toplink-plannet.de> wrote:
Hello,
> -----Original Message-----
> From: Andrei Pelinescu-Onciul
> [mailto:pelinescu-onciul@fokus.fraunhofer.de]
> Sent: Thursday, October 21, 2004 4:24 PM
> To: Martin Koenig
> Cc: serusers(a)lists.iptel.org
> Subject: Re: [Serusers] Loose Route
>
> On Oct 21, 2004 at 11:33, Martin Koenig
> <martin.koenig(a)toplink-plannet.de> wrote:
> > Hello,
> >
> > If a ser 0.8.14 named "server" receives the following message:
> >
> > ACK sip:final@destination:5060 SIP/2.0.
> > Route:
>
<sip:route@server:5060;ftag=0006283e0a6800774f26ee45-1c475c78;lr=on>.
> >
> > And loose_route() is called on that server, shouldn't it
> return true? Or is
> > loose_route() only true if there is another Route Header
> field left after
> > removing self?
>
> Yes, it would have been true if there was another route header.
> In fact loose_route returns true only if the message was "routed"
> according to the route headers. If there was no change in
the message
> destination (either request uri or the
destination uri),
it returns
> false.
> >
> > To my understanding, loose_route should return true if
> there was a Route
> > header field removed by the function, so that we know we
> have reached the
> > end of a server chain and can t_relay the request without
> further local
> > processing.
>
> If you are at the end of a server chain it will return
false, because
the
message will go to the request uri and not to an uri
extracted from
a route header.
Okay, I understand. Is there another way to distinguish
between a message
whose sip-uri should be processed and one that
should just
be forwarded
because it has reached the end of a loose routing
signalling chain?
Check if loose_route return false and if there was a Route header
present (search() or is_present_hf()).
I don't see though why you want to make this distinction
between messages at
the end of the routing chain and messages without Route. From my point
of view they are equivalent (in both cases they must be processed
according to the request uri).
Thank you for this hint! Very nice idea.
The difference is the following:
A message at the end of the routing-chain will have a, from the server's
point of view, remote location (uri==myself will return false). However, we
want to t_relay() this request.
On the other hand, we dont want to relay requests that are not "loose
routes" but still have a remote location, because this would make the server
an open relay.
The initial idea was to block all invites to remote locations and allow only
ACK, CANCEL etc, but this was creating problems with re-INVITEs.
The problem is that the R-URI is defined by the end devices
contact field
and might contain anything, and just using
uri==myself to
determine whether
the request should be forwarded or not opens
holes in the
design, because
the server would basically be an open relay.
I don't understand this either. To deny relaying look at From:.
If it has a local domain in it and if you can trust what's in
From (e.g.
challenge it & check_from()) relay it, if not drop it. You should do
this only for the initial message in the dialog (has_to_tag() is
false).
The server is a relaying server only, it has no knowledge of what domains
are "local" for the actual end user or not.
What is the module that provides has_to_tag()?
Best regards,
Martin