Unity socket connection failed

Questions & Answers
1

Here is the code for my C# server:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            TcpListener serverSocket = new TcpListener(8888);
            TcpClient clientSocket = default(TcpClient);
            serverSocket.Start();
            Console.WriteLine(" >> Server Started");
            clientSocket = serverSocket.AcceptTcpClient();
            Console.WriteLine(" >> Accept connection from client");
//          Console.ReadLine();

            while (true) {
                String textinput;
                textinput = Console.ReadLine ();
                NetworkStream serverStream = clientSocket.GetStream ();
                byte[] outStream = System.Text.Encoding.ASCII.GetBytes (textinput + "$");
                serverStream.Write (outStream, 0, outStream.Length);
                serverStream.Flush ();
            }

            clientSocket.Close();
            serverSocket.Stop();
            Console.WriteLine(" >> exit");
            Console.ReadLine();
        }

    }
}

Then here is the code for c# client:

using System;
using System.Net.Sockets;
using System.Text; 

namespace WindowsApplication1
{
    class Form1
    {
        static void Main(string[] args)
        {
            System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
            clientSocket.Connect("10.132.198.29", 8888);
            Console.WriteLine ("Running the client");

            while ((true))
            {
                try
                {
                    NetworkStream networkStream = clientSocket.GetStream();
                    byte[] bytesFrom = new byte[10025];
                    networkStream.Read(bytesFrom, 0, (int)bytesFrom.Length);
                    string dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                    dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                    Console.WriteLine(" >> Data from Server - " + dataFromClient);
                    string serverResponse = "Last Message from Server" + dataFromClient;
                    Byte[] sendBytes = Encoding.ASCII.GetBytes(serverResponse);
                    networkStream.Write(sendBytes, 0, sendBytes.Length);
                    networkStream.Flush();
                    Console.WriteLine(" >> " + serverResponse);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }
            // byte[] inStream = new byte[10025];
            // serverStream.Read(inStream, 0, (int)clientSocket.ReceiveBufferSize);

        }
    }
}

These all works fine in the terminal, but I want to convert the client into the unity project. So I create an empty object in my Unity project, and add the following code to the script, (made the few changes for the original c# client code).

using UnityEngine;
using System.Collections;
using System;
using System.Net.Sockets;
using System.Text; 


public class Client : MonoBehaviour {

    System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
    // Use this for initialization
    void Start () {
        System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
        clientSocket.Connect("10.132.198.29", 8888);
        Debug.Log ("Running the client");

    }

    // Update is called once per frame
    void Update () {
        try
        {
            NetworkStream networkStream = clientSocket.GetStream();
            byte[] bytesFrom = new byte[10025];
            networkStream.Read(bytesFrom, 0, (int)bytesFrom.Length);
            string dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
            dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
            Debug.Log(" >> Data from Server - " + dataFromClient);
            string serverResponse = "Last Message from Server" + dataFromClient;
            Byte[] sendBytes = Encoding.ASCII.GetBytes(serverResponse);
            networkStream.Write(sendBytes, 0, sendBytes.Length);
            networkStream.Flush();
            Debug.Log(" >> " + serverResponse);
        }
        catch (Exception ex)
        {
            Debug.Log("Exception error:"+ex.ToString());
        }
    }
}

Actually, when I run my unity project. I can see the server print “Accept connection from client”. When I change my ip, the unity project will stuck…So I think my unity project have successfully connected to the server. But in the unity project, the console print

Exception error:System.IO.IOException: Not connected
  at System.Net.Sockets.NetworkStream..ctor (System.Net.Sockets.Socket socket, FileAccess access, Boolean owns_socket) [0x00000] in <filename unknown>:0 
  at System.Net.Sockets.NetworkStream..ctor (System.Net.Sockets.Socket socket, Boolean owns_socket) [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.Net.Sockets.NetworkStream:.ctor (System.Net.Sockets.Socket,bool)
  at System.Net.Sockets.TcpClient.GetStream () [0x00000] in <filename unknown>:0 
  at Client.Update () [0x00000] in /Users/User/Unity3D/ClientTest/Assets/Client.cs:23 
UnityEngine.Debug:Log(Object)
Client:Update() (at Assets/Client.cs:37)

When I type something in the server’s terminal, it cannot print anything on the unity project console… Can anyone help… Quite confused for a long time…

2

You are not assigning the clientSocket field in your Client class in Start(). Remove System.Net.Sockets.TcpClient in front of clientSocket in Start, otherwise it is never assigned.

The thing that happens is that the local clientSocket variable gets initalized and assigned in Start(), and runs a server, but you can never access that server, as the variable for it disappears when the scope of the function ends.