[sr-dev] - ims_registrar_scscf: fix multiple contacts in 200OK

[Scherney Theodor]

Dear developer,

we have a question about the reasons of the changes made in this commit to Kamailio module ims_registrar_scscf

commit 23341c60519bd3e8eb91974c7aca0b283735665e
Author: Aleksandar Yosifov alexyosifov at gmail.com
Date:   Thu May 7 15:51:34 2020 +0300
ims_registrar_scscf: fix multiple contacts in 200OK
- Prevent sending of multiple contacts in 200OK reply
  for UE Re-Registration. Now S-CSCF replies with the
  exact contact for Re-Registration.
  
We read in Section 10.3 "Processing REGISTER Requests" of the RFC3261 ( https://datatracker.ietf.org/doc/html/rfc3261#section-10.3 ) :

8. The registrar returns a 200 (OK) response.  The response MUST contain Contact header field values enumerating all current bindings.

We have a test case where for one single IMPU there are two different consecutive REGISTER using different combination of IP/port.
Running our testcase on a version previous your commit, the 200OK of the second registration lists 2 bindings (correctly, as we expect by the RFC). After your commit, in this testcase, the 200OK lists only one binding. It seems that the changes in your commit do not match the RFC specifications. Can you please explain why these changes have been made?

Thanks and Kind Regards,