[C#]實作UDP Broadcast的傳送與接收

最近筆者想要利用廣播封包做些處理，稍微研究了一下，這篇簡單的做個紀錄。

若要發送UDP Broadcast，我們可以像下面這樣建立ProtocolType為Udp的Socket物件實體，呼叫SetSocketOption做些設定，並向IPAddress.Broadcast位置發送我們想要送出的廣播資料。 private static void BroadcastMessage(string message, int port) { BroadcastMessage(Encoding.ASCII.GetBytes(message), port); }

private static void BroadcastMessage(byte[] message, int port) { using (var sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)) { sock.EnableBroadcast = true; sock.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, true);

var iep = new IPEndPoint(IPAddress.Broadcast, port);

sock.SendTo(message, iep); } }

在接收廣播封包這邊，一樣我們要建立ProtocolType為Udp的Socket物件實體，將Socket綁定在IPAddress.Any位置，並用Socket.ReceiveFrom接收廣播的訊息。

private void ReceiveBroadcastMessage(Action receivedAction, int port) { ReceiveBroadcastMessage((ep, data) => { var stringData = Encoding.ASCII.GetString(data); receivedAction(ep, stringData); }, port); }

private void ReceiveBroadcastMessage(Action receivedAction, int port) { using (var sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)) { var ep = new IPEndPoint(IPAddress.Any, port) as EndPoint; sock.Bind(ep);

while (true) { var buffer = new byte[1024]; var recv = sock.ReceiveFrom(buffer, ref ep);

var data = new byte[recv];

Array.Copy(buffer, 0, data, 0, recv);

receivedAction(ep, data);

Thread.Sleep(500); Application.DoEvents(); } } }

最後附上完整的程式碼範例：

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Net; using System.Net.Sockets; using System.Text; using System.Threading; using System.Threading.Tasks; using System.Windows.Forms;

namespace WindowsFormsApplication8 { public partial class Form1 : Form { public Form1() { InitializeComponent(); }

private void button1_Click(object sender, EventArgs e) { BroadcastMessage(“This is a test message”, 9051); }

private void Form1_Load(object sender, EventArgs e) { backgroundWorker1.RunWorkerAsync(); }

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) { ReceiveBroadcastMessage((EndPoint ep, string data) => { this.Invoke((MethodInvoker)delegate() { listBox1.Items.Add(string.Format(“received: {0} from: {1}”, data, ep.ToString())); }); }, 9051); }

private static void BroadcastMessage(string message, int port) { BroadcastMessage(Encoding.ASCII.GetBytes(message), port); }

var iep = new IPEndPoint(IPAddress.Broadcast, port);

sock.SendTo(message, iep); } }

while (true) { var buffer = new byte[1024]; var recv = sock.ReceiveFrom(buffer, ref ep);

var data = new byte[recv];

Array.Copy(buffer, 0, data, 0, recv);

receivedAction(ep, data);

Thread.Sleep(500); Application.DoEvents(); } } } } }

運行結果如下：

Link

IP Multicasting in C#

[C#] 傳送與接收UDP廣播封包

Link#

Link