ListenConfig returns the default [net.ListenConfig] used by the plain-DNS servers in this module.

SortIPAddrs sorts addrs in accordance with the protocol preferences.

SortNetIPAddrs sorts addrs in accordance with the protocol preferences.

UDPGetOOBSize returns maximum size of the received OOB data.

UDPRead reads the message from conn using buf and receives a control-message payload of size udpOOBSize from it.

UDPSetOptions sets flag options on a UDP socket to be able to receive the necessary OOB data.

UDPWrite writes the data to the remoteAddr using conn.