mDNS Support for WebRTC at Google Chrome M74

[Koray Güney]

Google Chrome scheduled for M74 release that the mDNS support for local ICE candidates will be involved in the browser to increase privacy. This feature is controlled by the feature flag -enable-webrtc-hide-local-ips-with-mdns ;

I am trying to test the effect of mDNS support for WebRTC users on Google Chrome. I am testing with my custom WebRTC App and execute below test steps before making call;

1- WebRTC clients are logged in with using identical mDNS broadcast domains,

2- mDNS in Google Chrome Canary is enabled via -enable-webrtc-hide-local-ips-with-mdns flag on both party,

After the call has been generated, I saw that WebRTC agents are replaced their private IP's with anonymous local IP's which are followed by ".local";

Also I detect that the call signaling is generated and the media stream is performed successfully, but the ICE candidates are chosen from relay candidates(used TURN Server), not host candidates;

I think the parties cannot resolve their anonymous IP's and select to establish communication on existing TURN Server (use relay candidates).

I am sure that the clients are under the same subnet, but why they cannot resolve each other's anonymous IPs? I know that the nodes are broadcasted their anonymous IPs via 5353 port of mDNS and I expected that they will resolve the IPs easily. Is there anything that I missed during testing?

Your assistance would be highly appreciated. Thanks a lot

[qin...@google.com]

Hi Koray,

Thanks for letting us know the issue. Could you please provide the following info for the troubleshooting?

1. The version of Chrome and the platform you are testing with. You can paste them from the first few lines in chrome://version.

2. You could also give this data channel sample a try for a double check: https://webrtc.github.io/samples/src/content/datachannel/basic/. Make sure the media capture (getUserMedia) permission is purged for this origin. You can purge the permissions by chrome://settings and search for Site Settings or Content Settings depending on your platform, and remove the camera AND the microphone permissions if you have given any to this origin before.

3. If you can reproduce the issue, it would be great to also have the chrome debug log.  Please see the instruction in https://www.chromium.org/for-testers/enable-logging. TL;DR: you can launch via path-to-chrome --enable-logging -v=1 and the log file can be found in your user data directory in detailed in the link.