[Serusers] Rewriting URI in the Contact field

Maxim Sobolev sobomax at FreeBSD.org
Fri Jan 10 18:27:49 CET 2003


On Fri, Jan 10, 2003 at 03:37:46PM +0200, Maxim Sobolev wrote:
> Sounds reasonably - I'll do it that way.

I am planning add a new nathelper module, which will export the
following functions:

add_rport() - insert a rport= parameter into the first Via field
fix_nated_contact() - replaces host:port in Contact field with host:port
we received this message from
add_direction_passive() - adds direction=passive option to the SDP

Then it would be possible to do the following at the very top of config
before any other REGISTER/INVITE processing:

if (method == "INVITE" || method == "REGISTER") {
	if (search("User-Agent: Cisco ATA.*") {
		add_rport();
		if (method == "INVITE") {
			add_direction_passive();
		};
		if (method == "REGISTER") {
			fix_nated_contact();
		};
	};
};

Does it sound reasonably for you?

-Maxim

> 
> Thanks!
> 
> -Maxim
> 
> On Fri, Jan 10, 2003 at 02:15:11PM +0100, Jan Janak wrote:
> > On 10-01 14:32, Maxim Sobolev wrote:
> > > Folks,
> > > 
> > > I need an advise on how to better implement one feature, which isn't
> > > currently present in SER. We need to allow UAs behind NAT properly
> > > register with the registrar - by "properly" I mean that host:port portion
> > > of URI in Contact field should not be used, but host:port the request
> > > came from should be used instead. By definition we know that those UAs
> > > will support symmetric SIP signalling, so that this scheme will work just
> > > fine.
> > > 
> > > In my opinion there are two ways to do it: either add new rewritecontact*
> > > family of functions similar to rewritehost ones. or add a new flag for
> > > the save() function. This is where I need your help - which implementation
> > > looks better for you (or maybe you have even some better idea), since
> > > we are really interested in inclusion of our changes into the mainline to
> > > reduce our local hacks.
> > > 
> > 
> >   This should be implemented as a standalone module for ser. I want to keep
> >   registrar clean, it should not be aware of NATs. So, create a new module
> >   for ser that will contain all the NAT traversal helper functions, the
> >   functions will be then called from the config script.
> > 
> >   That includes modifications of contact, adding rport to Via and so on.
> >  
> >   regards, Jan.
> > 
> 
> 
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