If a STUN attribute is in the "comprehension-required" range (0x0000-0x7FFF), and the implementation does not recognize it, this should be treated as an error (as per RFC5389), with different behavior depending on the type of the message received. Bug: webrtc:9063 Change-Id: Ic31b0cdd3c26772c21d770b44fe4ee4a1b47030a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/64500 Commit-Queue: Taylor <deadbeef@webrtc.org> Reviewed-by: Jonas Oreland <jonaso@webrtc.org> Reviewed-by: Qingsi Wang <qingsi@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30925}