So that's for STUN/TURN servers only; we can't even parse FQDN-based candidates, much less resolve them: https://searchfox.org/mozilla-central/rev/d7e344e956d9da2808ea33e1fe0f963ed10c142d/dom/media/webrtc/transport/third_party/nICEr/src/ice/ice_parser.c#204,220
Bug 1239006 Comment 15 Edit History
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So that's for STUN/TURN servers only; we can't even parse FQDN-based candidates, much less resolve them: https://searchfox.org/mozilla-central/rev/d7e344e956d9da2808ea33e1fe0f963ed10c142d/dom/media/webrtc/transport/third_party/nICEr/src/ice/ice_parser.c#204,220 So if we're resolving hostnames in ICE candidates, it would need to be happening before we feed them into nICEr, which is what we do for mDNS, but we do not do the same for FQDN.