As we see offset based errors from ParseRIB, it is possible that we lose
track of framing on the socket. Restart the socket when this may have
occurred.
This change contains typically hairy concurrency around concurrent fd
handling. In the future we should change the netmon interface to have a
PAL that hides this kind of behavior to implicitly provide a concurrency
safe interface, in particular look to replace the receive API with
something more natural to the go concurrency environment.
Updates #14201
Signed-off-by: James Tucker <james@tailscale.com>
0d92be0cdf