C＃服务器客户端，客户端不重新连接

Question

thanks in advance for anything. Im making a server-client program, in which the server(application) creates a server and the client connects to it, i will also have a textbox and a button on the server application and whenever i write something on that textbox and press the button, it will send to the client application(there is only a textbox in this application, the only thing this application does is receive strings from the server application).

I think it works, kinda, but not the way i want it. I can make the connection and also send and receive the information from the textboxs, but only if i run the server application first(to create the server). The problem is that if i dont run the server application first(to create the server), the client application won't connect, or even try to.

Example of "Error"(i guess you can call it an error): If i run the client application first and then the server application, the client application just won't connect to the server that the server application created, i made a loop that basically verifies if the client is cnnected, if it is then it starts receiving the information, if not(else) waits for 3 seconds and tries to reconnect again. but when it tries to reconnect it doesnt work. Any ideas?

CODE IN C#:

    public Form1()
    {

        InitializeComponent();

    }

    private void Form1_Load(object sender, EventArgs e) //connect to server
    {
        client = new TcpClient();
        IPEndPoint IP_End = new IPEndPoint(IPAddress.Parse("192.168.254.34"), 123); // sincronizacao do IP com a porta
        try
        {

            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IAsyncResult result = client.BeginConnect(IPAddress.Parse("192.168.254.34"), 123, null, null);
            bool success = result.AsyncWaitHandle.WaitOne(3000, true);

            while (success)
            {

                if (client.Connected)
                {

                    STW = new StreamWriter(client.GetStream());
                    STR = new StreamReader(client.GetStream());
                    STW.AutoFlush = true;

                    backgroundWorker1.RunWorkerAsync(); // Começar a receber dados em background
                    backgroundWorker1.WorkerSupportsCancellation = true; // possibilidade de cancelar o fio

                }
                else
                {

                    int milliseconds = 3000;
                    Thread.Sleep(milliseconds);
                    MessageBox.Show("swag do elias!");

                    client.Connect(IP_End);
                }
            }


        }
        catch (SocketException exception)
        {
            MessageBox.Show("O erro é:", exception.Source);
        }
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) // Receber dados
    {
        while(client.Connected) //enquanto o cliente tiver conectado vai ler o que servidor diz em chat 
        {
            try
            {
                receive = STR.ReadLine();
                this.textBox2.Invoke(new MethodInvoker(delegate () { textBox2.Text=(receive + "\n\r"); }));
                receive = "";
            }
            catch(Exception x)
            {
                MessageBox.Show(x.Message.ToString());
            }
        }
    }
}

}

Answer 1

If the server isn't running yet, then success is always going to be false as a result of this line:

bool success = result.AsyncWaitHandle.WaitOne(3000, true);

Since success will always be false, the code inside of your while(success) block will never be executed.

Rearranging your code to something like this might be helpful:

client = new TcpClient();

bool success = false;
while (success == false)
{
    try
    {
        IAsyncResult result = client.BeginConnect(IPAddress.Parse("192.168.254.34"), 123, null, null);
        success = result.AsyncWaitHandle.WaitOne(3000, true);
    }
    catch (Exception ex)
    {
        success = false;
        MessageBox.Show("error connecting: " + ex.Message + " : " + ex.StackTrace);
    }
}

// NOW, by the time you reach this point, you KNOW that success == true and that you're connected, and you can proceed with the rest of your code

STW = new StreamWriter(client.GetStream());
STR = new StreamReader(client.GetStream());
STW.AutoFlush = true;

backgroundWorker1.RunWorkerAsync(); // Começar a receber dados em background
backgroundWorker1.WorkerSupportsCancellation = true; // possibilidade de cancelar o fio