Records any data received from the indicated socket stream. On playback, it will act as if the incoming data is coming over the wire again even if an actual connection is not available.
Outbound data will not be recorded, but will be sent straight through to the socket if it is connected, or silently ignored if it is not.
bool receive_datagram(Datagram &dg)
Receives a datagram over the socket by expecting a little-endian 16-bit byte count as a prefix. If the socket stream is non-blocking, may return false if the data is not available; otherwise, returns false only if the socket closes.