Hello list,
An UAC sends a resubscribe in the form
SUBSCRIBE sip:Alice@example.com SIP/2.0 Route: sip:sip.example.com;lr=on Route:sip:sip.next-hop.example.com;lr=on ....
The request has a to tag, from tag... Basic resubscribe(R-URI is the same as original SUBSCRIBE) The proxy that handles it is a Kamailio (1.5 but this refers to 3.1 as well). The problem is that loose_route() treats this request as coming from a strict routing router, not from the UAC, so it applies the strict-to-loose rules and rewrites the request as:
SUBSCRIBE sip:sip.next-hop.example.com;lr=on SIP/2.0 Route: sip:sip.example.com;lr=on ....
The segment that handles this is pretty standard:
if (loose_route()) { # sequential request withing a dialog should take the path # determined by record-routing if(has_totag()) { forward(); exit; }
It sees that message has Route set, it finds the to tag (so the routes were not a preset), and then , the important thing, sees that the domain from the RURI matches itself (kamailio has aliases configured for example.com), thus considering the request as coming from a strict router. Then it takes the bottom Route header and overwrites the RURI.
What is the best way to ensure that loose routing is applied to the resubscribe as described above?
Cheers, Marius
Not so easy .....
16.4 Route Information Preprocessing
The proxy MUST inspect the Request-URI of the request. If the Request-URI of the request contains a value this proxy previously placed into a Record-Route header field (see Section 16.6 item 4), the proxy MUST replace the Request-URI in the request with the last value from the Route header field, and remove that value from the Route header field. The proxy MUST then proceed as if it received this modified request.
This will only happen when the element sending the request to the proxy (which may have been an endpoint) is a strict router. This rewrite on receive is necessary to enable backwards compatibility with those elements. It also allows elements following this specification to preserve the Request-URI through strict-routing proxies (see Section 12.2.1.1).
Thus, Kamailio should somehow detect if the URI is inserted by himself or not. This may only happen if the previous hop is a strict-router. As Kamailio is a loose-router and always adds the ;lr parameter, the check could be extended to check if the RURI also cotains lr parameter. If the lr parameter is not present, this means for sure that the RURI was not generated by Kamailio.
Of course this would require code changes.
A dirty hack would be to manipulate the Route headers manually and set $du.
regards Klaus
Am 04.03.2011 15:25, schrieb marius zbihlei:
Hello list,
An UAC sends a resubscribe in the form
SUBSCRIBE sip:Alice@example.com SIP/2.0 Route: sip:sip.example.com;lr=on Route:sip:sip.next-hop.example.com;lr=on ....
The request has a to tag, from tag... Basic resubscribe(R-URI is the same as original SUBSCRIBE) The proxy that handles it is a Kamailio (1.5 but this refers to 3.1 as well). The problem is that loose_route() treats this request as coming from a strict routing router, not from the UAC, so it applies the strict-to-loose rules and rewrites the request as:
SUBSCRIBE sip:sip.next-hop.example.com;lr=on SIP/2.0 Route: sip:sip.example.com;lr=on ....
The segment that handles this is pretty standard:
if (loose_route()) { # sequential request withing a dialog should take the path # determined by record-routing if(has_totag()) { forward(); exit; }
It sees that message has Route set, it finds the to tag (so the routes were not a preset), and then , the important thing, sees that the domain from the RURI matches itself (kamailio has aliases configured for example.com), thus considering the request as coming from a strict router. Then it takes the bottom Route header and overwrites the RURI.
What is the best way to ensure that loose routing is applied to the resubscribe as described above?
Cheers, Marius
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
On 03/04/2011 04:56 PM, Klaus Darilion wrote:
Not so easy .....
16.4 Route Information Preprocessing
The proxy MUST inspect the Request-URI of the request. If the Request-URI of the request contains a value this proxy previously placed into a Record-Route header field (see Section 16.6 item 4), the proxy MUST replace the Request-URI in the request with the last value from the Route header field, and remove that value from the Route header field. The proxy MUST then proceed as if it received this modified request. This will only happen when the element sending the request to the proxy (which may have been an endpoint) is a strict router. This rewrite on receive is necessary to enable backwards compatibility with those elements. It also allows elements following this specification to preserve the Request-URI through strict-routing proxies (see Section 12.2.1.1).Thus, Kamailio should somehow detect if the URI is inserted by himself or not. This may only happen if the previous hop is a strict-router. As Kamailio is a loose-router and always adds the ;lr parameter, the check could be extended to check if the RURI also cotains lr parameter. If the lr parameter is not present, this means for sure that the RURI was not generated by Kamailio.
Hello,
I was thinking of maybe adding a new configurable RR param. A strict router would copy this header into the RURI. But a.t.m. loose_route does not perform any checking on tags. Maybe an exclude_uri_tag module param that can work like this:
modparam("rr", "exclude_uri_tag", "mark=on");
Then, when the initial SUBSCRIBE (dialog setting message) comes
add_rr_param(";mark=on");
In the loose_route processing, if exclude_uri_tag is set and !(RURI =~ exclude_uri_tag), then perform loose routing on that request (the request isn't coming from a strict router)
What do you think?
Marius
Of course this would require code changes.
A dirty hack would be to manipulate the Route headers manually and set $du.
regards Klaus
Am 04.03.2011 15:25, schrieb marius zbihlei:
Hello list,
An UAC sends a resubscribe in the form
SUBSCRIBE sip:Alice@example.com SIP/2.0 Route:sip:sip.example.com;lr=on Route:sip:sip.next-hop.example.com;lr=on ....
The request has a to tag, from tag... Basic resubscribe(R-URI is the same as original SUBSCRIBE) The proxy that handles it is a Kamailio (1.5 but this refers to 3.1 as well). The problem is that loose_route() treats this request as coming from a strict routing router, not from the UAC, so it applies the strict-to-loose rules and rewrites the request as:
SUBSCRIBE sip:sip.next-hop.example.com;lr=on SIP/2.0 Route:sip:sip.example.com;lr=on ....
The segment that handles this is pretty standard:
if (loose_route()) { # sequential request withing a dialog should take the path # determined by record-routing if(has_totag()) { forward(); exit; }
It sees that message has Route set, it finds the to tag (so the routes were not a preset), and then , the important thing, sees that the domain from the RURI matches itself (kamailio has aliases configured for example.com), thus considering the request as coming from a strict router. Then it takes the bottom Route header and overwrites the RURI.
What is the best way to ensure that loose routing is applied to the resubscribe as described above?
Cheers, Marius
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
On 03/04/2011 05:05 PM, marius zbihlei wrote:
On 03/04/2011 04:56 PM, Klaus Darilion wrote:
Not so easy .....
16.4 Route Information Preprocessing
The proxy MUST inspect the Request-URI of the request. If the Request-URI of the request contains a value this proxy previously placed into a Record-Route header field (see Section 16.6 item 4), the proxy MUST replace the Request-URI in the request with the last value from the Route header field, and remove that value from the Route header field. The proxy MUST then proceed as if it received this modified request. This will only happen when the element sending the request to the proxy (which may have been an endpoint) is a strict router. This rewrite on receive is necessary to enable backwards compatibility with those elements. It also allows elements following this specification to preserve the Request-URI through strict-routing proxies (see Section 12.2.1.1).Thus, Kamailio should somehow detect if the URI is inserted by himself or not. This may only happen if the previous hop is a strict-router. As Kamailio is a loose-router and always adds the ;lr parameter, the check could be extended to check if the RURI also cotains lr parameter. If the lr parameter is not present, this means for sure that the RURI was not generated by Kamailio.
Hello,
I was thinking of maybe adding a new configurable RR param. A strict router would copy this header into the RURI. But a.t.m. loose_route does not perform any checking on tags. Maybe an exclude_uri_tag module param that can work like this:
modparam("rr", "exclude_uri_tag", "mark=on");
Then, when the initial SUBSCRIBE (dialog setting message) comes
add_rr_param(";mark=on");
In the loose_route processing, if exclude_uri_tag is set and !(RURI =~ exclude_uri_tag), then perform loose routing on that request (the request isn't coming from a strict router)
What do you think?
Replying to myself..
Of course, this is almost the same as your idea, the question would this suffice, of a param to loose_route will be needed to enable/disable this behavior ?!
Marius
Marius
Of course this would require code changes.
A dirty hack would be to manipulate the Route headers manually and set $du.
regards Klaus
Am 04.03.2011 15:25, schrieb marius zbihlei:
Hello list,
An UAC sends a resubscribe in the form
SUBSCRIBE sip:Alice@example.com SIP/2.0 Route:sip:sip.example.com;lr=on Route:sip:sip.next-hop.example.com;lr=on ....
The request has a to tag, from tag... Basic resubscribe(R-URI is the same as original SUBSCRIBE) The proxy that handles it is a Kamailio (1.5 but this refers to 3.1 as well). The problem is that loose_route() treats this request as coming from a strict routing router, not from the UAC, so it applies the strict-to-loose rules and rewrites the request as:
SUBSCRIBE sip:sip.next-hop.example.com;lr=on SIP/2.0 Route:sip:sip.example.com;lr=on ....
The segment that handles this is pretty standard:
if (loose_route()) { # sequential request withing a dialog should take the path # determined by record-routing if(has_totag()) { forward(); exit; }
It sees that message has Route set, it finds the to tag (so the routes were not a preset), and then , the important thing, sees that the domain from the RURI matches itself (kamailio has aliases configured for example.com), thus considering the request as coming from a strict router. Then it takes the bottom Route header and overwrites the RURI.
What is the best way to ensure that loose routing is applied to the resubscribe as described above?
Cheers, Marius
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
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
On Friday 04 March 2011, Klaus Darilion wrote:
Am 04.03.2011 16:07, schrieb marius zbihlei:
What do you think?
Replying to myself..
Of course, this is almost the same as your idea, the question would this suffice, of a param to loose_route will be needed to enable/disable this behavior ?!
I think so.
Hello,
i like the discussed way without the additional parameter more, if it not interfere with possible other implementations which also maybe works the same way.
Cheers
Henning
-
Henning Westerholt -
Klaus Darilion -
marius zbihlei