[Freeswitch-users] Not proxying session refresh INVITEs when in bypass media mode

Spencer Thomason spencer at whiteskycommunications.com
Wed Apr 5 20:52:00 MSD 2017

Hello all,
Apologies if this is the wrong place for this type of discussion as its a little dev oriented.  JIRA/PR to follow once we get a little better direction.

We’re interested in adding a feature to ignore (i.e. not proxy across the bridge) session refresh INVITEs where the SDP has not changed when in bypass media mode, similarly to how ReINVITEs are handled in “normal” mode.  So a few questions:

- Does this already exist and I missed it?

- Is there any recommendation on when to consider the SDP “the same” as the previous SDP? The scenarios I can think of where we would definitely need proxy the ReINVITE are T38, holds and video attribute changes.  My thought is to just 200 OK codec changes that keep the same connection IP and port to keep things simpler but I’d like some feedback here.  Are there other scenarios I’ve missed?

- Where should we store the address and port for later comparison?  SWITCH_REMOTE_MEDIA_IP_VARIABLE (remote_media_ip) and SWITCH_REMOTE_MEDIA_PORT_VARIABLE (remote_media_port)?  Are these only used for audio currently?  I see there are another set for video...

- As we would need to parse the connection address and port in the SDP, what would be the preferred way?  Just use the sofia sdp parser?  Or do it manually?  Doing it manually might be faster but I’m sure there would be edge cases we would need to work out i.e. multiple c= lines, etc..  Or is there a “builtin” way I overlooked?

- Has anyone tried this and are there any horror stories?  

- Does anyone have any feedback for the best user interface handles?  I.e. potential channel variables and/or SIP profile params?  I was thinking something along the lines of a param called “nomedia-ignore-refresh-invite” but that might be confusing and hopefully someone has a better name :-)


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