Hi all!
Seems to be an old topic but still unclean is it possible or not, please correct me if I'm wrong. There are some old threads like http://lists.sip-router.org/pipermail/users/2007-May/011278.html
I use Kamailio 4.2.1 trying to create intercepting registrar proxy, which handles NAT (rewrites contact), forwards REGISTER to backend and then stores REGISTER in its internal location on 200 OK from backend, so I call save() from reply route in noreply mode.
The problem is, it stores IP source of reply as 'received' and modified contact which i sent out to backend server as 'contact', so it loses original information from initial REGISTER.
Is there a way to make save() use original request fields like T_req($ct), or some way to call save() with full set of custom params? Of course, I can save() all REGISTERs in request_route and then delete on backend fail, but it seems to be waste of resources, especially when REGISTER traffic is high :(
I'd be glad to hear any advice.
On 01/19/2015 12:56 PM, Dmitry Sytchev wrote:
Is there a way to make save() use original request fields like T_req($ct), or some way to call save() with full set of custom params?
Yes; in fact, there are many standards-based reasons why it's desirable to store the original Contact binding provided by the registrant. Many devices (e.g. ATAs, various gateways, for instance) will not accept an INVITE with an incoming Request URI that does not correspond to the exact Contact URI that it sent in the REGISTER request.
This is why Kamailio's usrloc record provides a 'received' field in addition to a 'contact' field. Take a look at this:
http://kamailio.org/docs/modules/4.2.x/modules/registrar.html#registrar.p.re...
In essence, what you want is for the external IP:port to be stored in the 'received' value while the original Contact is stored in the 'contact' value. The 'received' value will be used as the destination set ($du) for inbound routing, while the Request URI will remain consistent with the Contact URI.
The issue of having two proxies is a separate and more complex one. Ultimately, to make it work, you're going to need to use Path, which is like Record-Route, but for REGISTERs:
http://kamailio.org/docs/modules/4.2.x/modules/registrar.html#registrar.p.pa...
But, the first step to solving your problem is to realise that you should not actually be rewriting the Contact header as your NAT traversal strategy. You should add the received IP:port as parameters in one way or another to be passed onto the receiving registrar, as for example using Contact URI header parameters per the received_param doc I linked to above.
-- Alex
Yes, you're right about contact matching and ATAs, this is a part of our case too. I actually use Path module to forward REGISTERs to backend servers. But there is a problem that not all backends support Path, like Asterisk 11.
If I get the point right, I should forward them as is and when I receive request from backend set $ru to contact and $du to Contact's received parameter?
2015-01-19 22:02 GMT+04:00 Alex Balashov abalashov@evaristesys.com:
On 01/19/2015 12:56 PM, Dmitry Sytchev wrote:
Is there a way to make save() use original request fields like
T_req($ct), or some way to call save() with full set of custom params?
Yes; in fact, there are many standards-based reasons why it's desirable to store the original Contact binding provided by the registrant. Many devices (e.g. ATAs, various gateways, for instance) will not accept an INVITE with an incoming Request URI that does not correspond to the exact Contact URI that it sent in the REGISTER request.
This is why Kamailio's usrloc record provides a 'received' field in addition to a 'contact' field. Take a look at this:
http://kamailio.org/docs/modules/4.2.x/modules/registrar.html#registrar.p. received_param
In essence, what you want is for the external IP:port to be stored in the 'received' value while the original Contact is stored in the 'contact' value. The 'received' value will be used as the destination set ($du) for inbound routing, while the Request URI will remain consistent with the Contact URI.
The issue of having two proxies is a separate and more complex one. Ultimately, to make it work, you're going to need to use Path, which is like Record-Route, but for REGISTERs:
http://kamailio.org/docs/modules/4.2.x/modules/registrar.html#registrar.p. path_mode
But, the first step to solving your problem is to realise that you should not actually be rewriting the Contact header as your NAT traversal strategy. You should add the received IP:port as parameters in one way or another to be passed onto the receiving registrar, as for example using Contact URI header parameters per the received_param doc I linked to above.
-- Alex
-- Alex Balashov - Principal Evariste Systems LLC 235 E Ponce de Leon Ave Suite 106 Decatur, GA 30030 United States
Tel: +1-678-954-0670 Web: http://www.evaristesys.com/, http://www.alexbalashov.com/
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
BTW, is there any way to alias contacts on Kamailio side and then on INVITE use rewritten contact as base for real (original untouched) contact lookup, like using 'received' field as lookup source?
And thanks for your detailed reply, I'll dig into the docs about 'received' handling.
2015-01-19 22:23 GMT+04:00 Dmitry Sytchev kbdfck@gmail.com:
Yes, you're right about contact matching and ATAs, this is a part of our case too. I actually use Path module to forward REGISTERs to backend servers. But there is a problem that not all backends support Path, like Asterisk 11.
If I get the point right, I should forward them as is and when I receive request from backend set $ru to contact and $du to Contact's received parameter?
2015-01-19 22:02 GMT+04:00 Alex Balashov abalashov@evaristesys.com:
On 01/19/2015 12:56 PM, Dmitry Sytchev wrote:
Is there a way to make save() use original request fields like
T_req($ct), or some way to call save() with full set of custom params?
Yes; in fact, there are many standards-based reasons why it's desirable to store the original Contact binding provided by the registrant. Many devices (e.g. ATAs, various gateways, for instance) will not accept an INVITE with an incoming Request URI that does not correspond to the exact Contact URI that it sent in the REGISTER request.
This is why Kamailio's usrloc record provides a 'received' field in addition to a 'contact' field. Take a look at this:
http://kamailio.org/docs/modules/4.2.x/modules/ registrar.html#registrar.p.received_param
In essence, what you want is for the external IP:port to be stored in the 'received' value while the original Contact is stored in the 'contact' value. The 'received' value will be used as the destination set ($du) for inbound routing, while the Request URI will remain consistent with the Contact URI.
The issue of having two proxies is a separate and more complex one. Ultimately, to make it work, you're going to need to use Path, which is like Record-Route, but for REGISTERs:
http://kamailio.org/docs/modules/4.2.x/modules/ registrar.html#registrar.p.path_mode
But, the first step to solving your problem is to realise that you should not actually be rewriting the Contact header as your NAT traversal strategy. You should add the received IP:port as parameters in one way or another to be passed onto the receiving registrar, as for example using Contact URI header parameters per the received_param doc I linked to above.
-- Alex
-- Alex Balashov - Principal Evariste Systems LLC 235 E Ponce de Leon Ave Suite 106 Decatur, GA 30030 United States
Tel: +1-678-954-0670 Web: http://www.evaristesys.com/, http://www.alexbalashov.com/
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
-- Best regards,
Dmitry Sytchev, IT Engineer
-
Alex Balashov -
Dmitry Sytchev