请教各位大佬，关于socket异步接收数据的代码，不太理解BeginReceive和EndReceive在.net里实现的机制，想看.net里的源码，求指导！

代码如下：

//Receive回调
    public void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            Socket socket = (Socket)ar.AsyncState;
            int count = socket.EndReceive(ar);
            recvStr = System.Text.Encoding.Default.GetString(readBuff, 0, count);

            socket.BeginReceive(readBuff, 0, 1024, 0, ReceiveCallback, socket);
        }
        catch(SocketException ex)
        {
            Debug.Log("Socket Receive Fail " + ex.ToString());
        }
    }