Fix webrtc glare

[dextertanyj]

Context

When two client simultaneously announce themselves to the signalling server, they will both create a Peer with { initiator: true } before sending the offer message to each other. As such, both parties will attempt to answer each other's offer and the second answer will result in an ERR_SET_REMOTE_DESCRIPTION. Thereafter, the connection closes and the when the reconnection takes place, both clients have { initiator: false }, causing a standstill as they wait for each other.

This issue is similar to glare, and simple-peer is unlikely to handle this issue in the foreseeable future based on previous discussion.

Approach

• Generate a tiebreaker value glareToken for each webrtc connection object when a signal event occurs.
• Include the tiebreaker value for signal messages.
• When a client receives an offer message with a lower tiebreaker value, it is ignored.
• Tiebreaker values are cleared on both sides of the webrtc connection when a successful connection is established.

[dmonad]

Thank you, I didn't know about this!

This looks good, I'm gonna put this in the next release.