Make the adept socket nonblocking earlier to avoid hangs in the handshake.
Make the adept socket nonblocking earlier to avoid hangs in the handshake.

tls::handshake in blocking mode can hang forever, blocked on read waiting
for data from the remote side that never arrives (e.g. network drops while
we are waiting for remote data for long enough that the remote side
gives up on retransmits)

So do a nonblocking handshake, waiting for more data asynchronously
whenever tls::handshake returns 0 (handshake not completed yet)

flightaware/piaware,flightaware/piaware