Hi, Robert!
For a request, VIA 1 is always the previous hop - therefore, if you want
to have different offer messages, you need to use something else - my
proposal is to use the via-branch=3 and set the extra_avp to
$T_branch_idx. You can do the same thing for replies, and that should
cover all cases.
Best regards,
Răzvan Crainea
OpenSIPS Core Developer
http://www.opensips-solutions.com
On 1/27/22 19:23, Robert Dyck wrote:
Opensips adds its via ( with branch info ) after script processing but before
forwarding. Opensips branch info is not available to the script when
processing an INVITE. I have attached some text of an INVITE with rtpengine
and with "offer via-branch=1". What rtpengine receives is the branch parameter
added by the upstream node. The upstream node has no knowledge of any forking
that may occur after lookup.
The branch parameter is a legacy of rfc2543. That rfc stated that a forking
proxy would add branch info in a via parameter called branch. This parameter
could be added by any hop but is ignored. It was only meaningful in a response
received by the forking proxy.
Rfc3261 retained the via parameter name, I assume for compatibility. Rfc3261
was clear however that "branch" was now a transaction ID. This is only of
interest to the node that added it in a request. Now in the case of a forking
proxy the branch parameter has the dual role of being a transaction ID and a
branch ID. Opensips does this by adding the branch index as a suffix to the
transaction ID.
The opensips script may not have access to the eventual transaction ID but the
branch index is available. Passing the branch index to rtpengine causes it to
create a different profile for each branch rather than stacking the profiles.
That stacking was causing trouble for me.
When rtpengine is simply providing a public address to relay media the
stacking does not appear to have any consequence. However when mixing WEBRTC
and non-WEBRTC stacking the profiles in a single entry in rtpengine gives
inconsistent results.
On Thursday, January 27, 2022 3:57:07 A.M. PST Răzvan Crainea wrote:
Hi, Robert!
Are you sure that via-branch=2 does not set different branches, and sets
the same param as via-branch=1?
If you are going to use the extra_id_pv, you should make sure that you
persist it over dialog, i.e. also provide it during sequential
offer/answer/delete commands.
Best regards,
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