[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<EndPoint, string> receivedAction, int port)
{
ReceiveBroadcastMessage((ep, data) =>
{
var stringData = Encoding.ASCII.GetString(data);
receivedAction(ep, stringData);
}, port);
}

private void ReceiveBroadcastMessage(Action<EndPoint, byte[]> 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);
}

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);
}
}

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

private void ReceiveBroadcastMessage(Action<EndPoint, byte[]> 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();
}
}
}
}
}

運行結果如下:

image

Link


  • IP Multicasting in C#


  • [C#] 傳送與接收UDP廣播封包