[Serusers] Rewriting URI in the Contact field

[Maxim Sobolev]

On Fri, Jan 10, 2003 at 08:38:03PM +0100, Jan Janak wrote:
> Sounds good, go ahead. If you need any implementation-related advice, post
> a message to the mailing list, I will try to reply asap, some parts haven't
> been well documented yet so don't hesitate to ask.

Thank you for your kind proposal!

I have one question:

Am I correct that in order to change some field in header I have to do
the following:

1. Check that _m->somefield is NULL and call parse_headers() with the
appropriate HDR_FOO flag.
2. Check that _m->somefield is non-NULL and return if false.
3. Modify _m->somefield according to the type of that field.
4. Using del_lump() mark original version of the header for deletion and
using insert_new_lump() indicate where modified version should be placed
before sending a message out.

-Maxim

> 
>   regards, Jan.
> 
> On 10-01 19:27, Maxim Sobolev wrote:
> > 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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