05c79ac8c2
This should resolve the spurious ping timeouts we've had on low powered boxes. Those errors are the result of us requiring a timely Pong response to our Pings. However this is unnecessarily strict - as long as we've received *anything* recently, we know the other peer is alive. So the new mechanism removes the Pong message entirely and separates the ping check into two routines: - One that makes sure to send ping periodically, if nothing else has been sent. This guarantees a message sent every 45-90 seconds. - One that checks how long it was since we last received a message. If it's longer than 300 seconds, we trigger an ErrTimeout. So we're guaranteed to detect a connection failure in 300 + 300/2 seconds (due to how often the check runs) and we may detect it much sooner if we get an actual error on the ping write (a connection reset or so). This is more sluggish than before but I think that's an OK price to pay for making it actually work out of the box. This removes the configurability of it, as the timeout on one side is dependent on the send interval on the other side. Do we still need it configurable?
The BEPv1 Protocol
This is the protocol implementation used by Syncthing.
License
MIT