code: func NewBroadcastUDPConn(rawPacketConn net.PacketConn, boundAddr *net.UDPAddr) net.PacketConn {
  	return &UDPPacketConn{
  		PacketConn: rawPacketConn,
  		boundAddr:  boundAddr,
  	}
  }
docs: // NewBroadcastUDPConn returns a PacketConn that marshals and unmarshals UDP
  // packets, sending them to the broadcast MAC at on rawPacketConn.
  //
  // Calls to ReadFrom will only return packets destined to boundAddr.