Static configuration of SRTP forwarding doesn't work in audiobridge plugin

[willamowius]

The config file switches rtp_forward_srtp_suite and rtp_forward_srtp_crypto are never read in the source code and SRTP is not enabled.

When dynamically enabling forwarding through the API, SRTP parameters (srtp_suite and srtp_crypto) are used.

[lminiero]

Mh, looks like a typo due to some copy paste: the code to read and use them is indeed there, see
https://github.com/meetecho/janus-gateway/blob/master/plugins/janus_audiobridge.c#L1894

but it's reading srtp_suite and srtp_crypto (which is what the API expects) rather than rtp_forward_srtp_suite and rtp_forward_srtp_crypto (which is what we'd expect in the configuration file). Should be an easy fix, thanks for spotting it 👍

[willamowius]

The patch causes the "listforwarders" command to show the forwarder as using SRTP, but Janus can't decrypt the resulting media stream, even so both sides use the same suit and crypto string.

[lminiero]

You may want to check if it does work when doing SRTP forwarding from the VideoRoom instead.

[lminiero]

Another thing you can try is changing ssrc_any_inbound to ssrc_any_outbound in the AudioBridge code, since the SRTP forwarder will just send media and never receive any.

[lminiero]

Actually, turns out there's no srtp_protect call in the plugin at all... no surprise it doesn't work in the AudioBridge! It works as expected in the VideoRoom instead, where we do make use of the SRTP code. I'll try and put it in there later today.

[lminiero]

Ok, should be fixed now.

[willamowius]

Looks good, thanks!