'Unable to send acknowledgemnt properly in TCP connection (C#)

I have a client server model.

192.168.77.6 is the client (my code). 192.168.77.18 is a server device. I am sending a request to the server for a response. Once I get the response, I am reading the response and trying to send an acknowledgement of 2 bytes (line 479 of wireshark packet). But, before I can send my acknowledgement, I see that an acknowledgement of 0 bytes is being sent from the client (line 429 of wireshark packet), which causes the server device to send a [FIN,ACK] packet (line 475 of wireshark packet), and it doesn't accept the acknowledgement that I am sending (line 479 of wireshark packet).

Below is the screenshot of the wireshark packets obtained:

Wireshark packet screenshot

I have included my code below:

TcpClient tcpclnt;
NetworkStream stream;
tcpclnt = new TcpClient();
tcpclnt.Connect(ip, port);
stream = tcpclnt.GetStream();
if (tcpclnt.Connected)
{
    SendMessage(stream, RequestToSend);
    Thread.Sleep(2000);
    string readData = "";
    readData = readBytes1(stream);                
}
tcpclnt.Close();

Below is the readBytes1() function:

private static string readBytes1(NetworkStream stream)
        {
            byte[] resp = new byte[100];
            var memoryStream = new MemoryStream();
            int bytes;
            do
            {
                bytes = 0;
                bytes = stream.Read(resp, 0, resp.Length);
                memoryStream.Write(resp, 0, bytes);                
            }
            while (bytes > 0);

            GenerateAcknowledgement(stream);
            

            return Encoding.GetEncoding("ISO-8859-1").GetString(memoryStream.ToArray());

        }

GenerateAcknowledgement() is the function that sends 2 bytes of data.

c++sharpsocketstcpnetwork-programmingwireshark


Solution 1:[1]

You need to obtain the server and protocol.

The server is closing the connection. This will be in the design of the server.

It's possible that you're not doing something in the request to the server which causes it to close immediately.

Without knowing the protocol or having the server code it's not possible to know why the the server is closing the connection.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Rowan Smith

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