Question

我无法连接简单的客户端和简单的服务器。当我运行服务器时似乎没有任何问题，但是当我尝试向客户端发送数据时，它会抛出一个异常，说它在超时期限内没有连接。

这是我正在使用的服务器代码：

    public void server()
    {
        try
        {
            byte[] bytes = new byte[1024];
            int bytesReceived = 0;
            String message = "";
            IPAddress direction = IPAddress.Parse(getIPExternal()); //getIPExternal return the public IP of the machine in which the programm runs
            IPEndPoint directionPort = new IPEndPoint(direction, 5656);
            Socket socketServer = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            socketServer.Bind(directionPort);
            socketServer.Listen(100);
            while (true)
            {
                Socket client = socketServer.Accept();
                bytesReceived = client.Receive(bytes);
                message = System.Text.Encoding.Unicode.GetString(bytes, 0, bytesReceived);

                editMultiline.Invoke(new writeMessageDelegate(writeMessage), new object[] { message, "client"}); //Ignore this, it is just to show the info in a textbox because the server code runs in a diferent thread

                client.Shutdown(SocketShutdown.Both);
                client.Close();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Server error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }

这样我从运行程序的机器上获取公共IP：

    public string getIPExternal()
    {
        string direction;
        WebRequest request = WebRequest.Create("http://checkip.dyndns.org/");
        WebResponse response = request.GetResponse();
        StreamReader stream = new StreamReader(response.GetResponseStream());
        direction = stream.ReadToEnd();
        stream.Close();
        response.Close();

        //Search for the ip in the html
        int first = direction.IndexOf("Address: ") + 9;
        int last = direction.LastIndexOf("</body>");
        direction = direction.Substring(first, last - first);

        return direction;
    }

这是我的客户代码：

    public void client(string directionIP, string message) //directionIP is the IP from the computer to which i want to get connected
    {
        try
        {
            byte[] bytesSend = System.Text.Encoding.Unicode.GetBytes(message);
            IPAddress direction = IPAddress.Parse(directionIP);
            IPEndPoint directionPort = new IPEndPoint(direction, 5656);
            Socket socketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            socketClient.Connect(directionPort);
            socketClient.Send(bytesSend);
            socketClient.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Client error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }

任何建议都会很棒。

Answer 1

我建议查看TcpListener和TcpClient类，而不是使用套接字.. Tcp *类为你做了所有这些事情

Answer 2

获取公共IP意味着您在NAT设备（如简单的家庭路由器）之后。您是否确保设备将TCP连接转发到端口5656到服务器计算机并且还配置了服务器的防火墙？

Answer 3

请尝试此代码。也许没有资源泄漏，它会更好地工作：

public void server()
{
    try
    {
        byte[] bytes = new byte[1024];
        IPAddress direction = IPAddress.Parse(getIPExternal()); //getIPExternal return the public IP of the machine in which the programm runs
        IPEndPoint directionPort = new IPEndPoint(direction, 5656);
        using (Socket socketServer = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
        {
            socketServer.Bind(directionPort);
            socketServer.Listen(100);
            while (true)
            {
                using (Socket client = socketServer.Accept())
                {
                    int bytesReceived = client.Receive(bytes);
                    String message = System.Text.Encoding.Unicode.GetString(bytes, 0, bytesReceived);

                    editMultiline.Invoke(new writeMessageDelegate(writeMessage), new object[] { message, "client" }); //Ignore this, it is just to show the info in a textbox because the server code runs in a diferent thread

                    client.Shutdown(SocketShutdown.Both);
                }
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString(), "Server error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

public string getIPExternal()
{
    WebRequest request = WebRequest.Create("http://checkip.dyndns.org/");
    string direction;
    using (WebResponse response = request.GetResponse())
    {
        using (Stream responseStream = response.GetResponseStream())
        {
            using (StreamReader reader = new StreamReader(responseStream))
            {
                direction = reader.ReadToEnd();
            }
        }
    }

    //Search for the ip in the html
    int first = direction.IndexOf("Address: ") + 9;
    int last = direction.LastIndexOf("</body>");
    return direction.Substring(first, last - first);
}

客户：

public void client(string directionIP, string message) //directionIP is the IP from the computer to which i want to get connected
{
    try
    {
        byte[] bytesSend = System.Text.Encoding.Unicode.GetBytes(message);
        IPAddress direction = IPAddress.Parse(directionIP);
        IPEndPoint directionPort = new IPEndPoint(direction, 5656);
        using (Socket socketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
        {
            socketClient.Connect(directionPort);
            socketClient.Send(bytesSend);
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString(), "Client error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

Answer 4

这里有很多失败的空间。除非您手动输入，否则客户端能够猜测服务器IP地址的几率很小。它也必须在另一个网络上运行。如果您使用两台靠近的计算机进行测试，请考虑使用本地IP地址，如果您在同一台计算机上进行测试，则考虑使用127.0.0.1。并且防火墙几乎肯定会阻止端口号。你必须为它做一个明确的例外。

.NET中的套接字无法连接

4 个答案: