在unity里面 怎么得到接收udp消息的消息头

在unity里面 怎么得到接收udp消息的消息头
初始化
ipEnd = new IPEndPoint(IPAddress.Parse(ipAddress), ConnectPort);
socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
socket.Bind(ipEnd);
//定义客户端
IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
clientEnd = (EndPoint)sender;
//开启一个线程连接
connectThread = new Thread(new ThreadStart(SocketReceive));
connectThread.Start();
接收 recvData = new byte[81920];
recvLen = socket.ReceiveFrom(recvData, ref clientEnd);
recvStr = Encoding.UTF8.GetString(recvData, 0, recvLen);