c# - UDPClient 接收方法在服务中不起作用

Question

我一直在试验 C# 中的 UDP 发送和接收，但遇到了一个奇怪的问题。该代码在控制台应用程序中运行良好，但当我尝试在服务中使用完全相同的代码时，client.Receive 方法被阻止。该服务正常运行并且不会中止，并且我已将日志记录写入文本文件，因此我知道它到达了接收。有人有主意吗？下面的代码...

public partial class Service1 : ServiceBase
{
    private bool serviceStarted = false;
    Thread listenerThread;

    public Service1()
    {
        InitializeComponent();      
    }

    protected override void OnStart(string[] args)
    {
        serviceStarted = false;
        WriteLog("UDPListener Service Starting");

        ThreadStart thread = new ThreadStart(StartListening);
        listenerThread = new Thread(thread);

        serviceStarted = true;
        listenerThread.Start();
    }

    protected override void OnStop()
    {
        WriteLog("UDPListener Service Stopping");

        serviceStarted = false;
        listenerThread.Join(new TimeSpan(0, 0, 5));
    }

    private void StartListening()
    {
        WriteLog("Worker thread spawned.");

        UdpClient client = new UdpClient(40000);

        while (serviceStarted)
        {
            WriteLog("Service is started.  Getting endpoint.");
            IPEndPoint remoteIPEndPoint = new IPEndPoint(IPAddress.Any, 40000);
            WriteLog("Thread is listening...");

            byte[] content = client.Receive(ref remoteIPEndPoint);
            WriteLog("Receive unblocked.");

            if (content.Length > 0)
            {
                string message = Encoding.ASCII.GetString(content);
                WriteLog("UDPListener Message = " + message);
            }
        }
        Thread.CurrentThread.Abort();
    }

    private void WriteLog(string strMessage)
    {
        FileStream filestream = new FileStream(@"c:\temp\UDPClientLog.txt", 
                                       FileMode.OpenOrCreate, 
                                       FileAccess.Write);
        StreamWriter streamwriter = new StreamWriter(filestream);
        streamwriter.BaseStream.Seek(0, SeekOrigin.End);

        streamwriter.WriteLine(DateTime.Now.ToLongDateString() +
            " at " +
            DateTime.Now.ToLongTimeString() +
            ": " +
            strMessage +
            "\n");

        streamwriter.Flush();
        streamwriter.Close();
    }
}

Answer 1

终于明白了。 Windows 防火墙阻止了传入连接，显然不允许该服务以交互方式请求取消阻止它的权限。