We Keep Coding

check when a client is disconnected

I have a console application in c#
this code can tell me when a client si connected in TCP to port 3001 and the message sent
I cant understand when he disconnects, its going into while (client.Connected) unlimited, i tried to check with a PING but sometimes returns false even if connnected,
I am stuck
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
namespace ConsoleApp2
{
class Program
{
static void Main(string[] args)
{
int port = 3001;
TcpListener listener = new TcpListener(IPAddress.Any, port);
listener.Start();
Console.WriteLine("Listening on port " + port + "...");
while (true)
{
TcpClient client = listener.AcceptTcpClient();
Console.WriteLine("Accepted connection from " + client.Client.RemoteEndPoint.ToString());
while (client.Connected)
{
NetworkStream stream = client.GetStream();
if (stream.DataAvailable)
{
byte[] buffer = new byte[1024];
int bytesRead = stream.Read(buffer, 0, buffer.Length);
string data = Encoding.UTF8.GetString(buffer, 0, bytesRead);
Console.WriteLine("Received data: " + data);
}
//check if client still connected
string[] cli = client.Client.RemoteEndPoint.ToString().Split(Convert.ToChar(":"));
string Host = cli[0];
int Uri = port;// int.Parse(cli[1]);
if (PingHost(Host,Uri)==false)
{
Console.WriteLine("Client disconnected.");
break;
}
}
}
}
public static bool PingHost(string hostUri, int portNumber)
{
try
{
using (var client = new TcpClient(hostUri, portNumber))
return true;
}
catch (SocketException ex)
{
//MessageBox.Show("Error pinging host:'" + hostUri + ":" + portNumber.ToString() + "'");
return false;
}
}
}
}

C# create multi threaded socket server and select client/connection

Currently, I'm programming in C#, I would like to modify the code below to isolate one client connection. so like creating a break-out room from the main pool.
Below are 2 files, one is just the basic standard .NET Framework Console App Program.cs file; the other is the server file. Combined, they both can make a multi-threaded server, but I would like one that allows me to also select a client to connect to in case if I were to create a remote control application as my friend did.
On a side note, I would like to share that I want to be able to connect to a client by entering connect [1,2,3,etc..] into the console.
Answers
If you answer, please put some code, It would really, really help. I learn a lot better by looking att the code rather than reading documentation.
Code
Server.cs
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
namespace TCPServer
{
class Server
{
TcpListener server = null;
int counter = 0;
public Server(string ip, int port)
{
IPAddress localAddr = IPAddress.Parse(ip);
server = new TcpListener(localAddr, port);
server.Start();
StartListener();
}
public void StartListener()
{
try
{
while (true)
{
Console.WriteLine("Waiting for incoming connections...");
TcpClient client = server.AcceptTcpClient();
counter += 1;
Console.WriteLine("Connected to authorized client: {0}", counter);
Thread t = new Thread(new ParameterizedThreadStart(HandleDeivce));
t.Start(client);
}
}
catch (SocketException e)
{
Console.WriteLine("SocketException: {0}", e);
server.Stop();
}
}
public void HandleDeivce(Object obj)
{
TcpClient client = (TcpClient)obj;
var stream = client.GetStream();
string imei = String.Empty;
string data = null;
Byte[] bytes = new Byte[256];
int i;
try
{
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
string hex = BitConverter.ToString(bytes);
data = Encoding.ASCII.GetString(bytes, 0, i);
Console.WriteLine("{1}: Received: {0}", data, Thread.CurrentThread.ManagedThreadId);
if (data != "auth token")
{
stream.Close();
client.Close();
}
string str = "Device authorization successfull";
Byte[] reply = System.Text.Encoding.ASCII.GetBytes(str);
stream.Write(reply, 0, reply.Length);
Console.WriteLine("{1}: Sent: {0}", str, Thread.CurrentThread.ManagedThreadId);
}
}
catch (Exception e)
{
Console.WriteLine("Exception: {0}", e.ToString());
client.Close();
}
}
}
}
Program.cs
using System;
using System.Threading;
namespace TCPServer
{
class Program
{
static void Main(string[] args)
{
Thread thread = new Thread(delegate()
{
Server server = new Server("127.0.0.1", 13000);
});
thread.Start();
Console.WriteLine("Server started...");
}
}
}

C# TCP Application won't work

I'm making a simple chat application using TcpClient and TcpServer from System.Net.
I got everything working on my PC, the server communicates with the client and vice versa. But when I try to connect to the same server application using another PC (even on the same subnet as my PC) the thing doesn't work.
I've tried port-forwarding through my router, firewall and still nothing.
The Can you see me website says that the connection is being refused. Although!! Sometimes it says that the connection is timed out completely.
I am not sure what's wrong with my code or my PC, I would really appreciate some help from people that are more experienced in this area than I am.
Here is the configuration for the port forwarding in my router:
If you need the code for the client and the server, here they are:
P.S. I make the change to the client in the BeginConnect() part at the bottom in order to change the IP address that I'm connecting to
Client:
using System;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
namespace TcpTest_Client_
{
public partial class Form1 : Form
{
TcpClient client;
IPAddress localIP = null;
bool connected = false;
public Form1()
{
InitializeComponent();
}
public void clientConnectCallback(IAsyncResult result)
{
try
{
client.EndConnect(result);
Log("Connected to " + client.Client.RemoteEndPoint);
connected = true;
NetworkStream clientStream = client.GetStream();
byte[] message = new byte[4096];
int bytesRead;
while (true)
{
bytesRead = 0;
try
{
//blocks until a client sends a message
bytesRead = clientStream.Read(message, 0, 4096);
}
catch (Exception ex)
{
//a socket error has occured
Log(ex.Message);
break;
}
if (bytesRead == 0)
{
//the client has disconnected from the server
Log("Server on has disconnected");
break;
}
//message has successfully been received
UTF8Encoding encoder = new UTF8Encoding();
string bufferincmessage = encoder.GetString(message, 0, bytesRead);
Log("Server: " + bufferincmessage);
}
}
catch (Exception ex)
{
Log(ex.Message);
}
}
public void Log(string msg)
{
richTextBox1.BeginInvoke(new Action(
() =>
{
richTextBox1.Text += msg + "\n";
}));
}
private void Form1_Load(object sender, EventArgs e)
{
foreach (IPAddress addr in Dns.GetHostAddresses(Dns.GetHostName()))
{
if (addr.AddressFamily == AddressFamily.InterNetwork)
{
localIP = addr;
break;
}
}
client = new TcpClient(AddressFamily.InterNetwork);
}
private void button2_Click(object sender, EventArgs e)
{
try
{
client.BeginConnect(IPAddress.Parse("109.252.107.144"), 1234, clientConnectCallback, client);
}
catch (Exception ex)
{
Log(ex.Message);
}
}
private void button1_Click(object sender, EventArgs e)
{
if (connected)
{
UTF8Encoding encoder = new UTF8Encoding();
NetworkStream clientStream = client.GetStream();
byte[] stringToSend = new byte[richTextBox2.Text.Length];
stringToSend = encoder.GetBytes(richTextBox2.Text);
clientStream.Write(stringToSend, 0, stringToSend.Length);
}
}
}
}
Server:
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace TcpTest
{
public partial class Form1 : Form
{
private TcpListener server;
private List<Thread> clientThreads = null;
public Thread MainThread;
public Form1()
{
InitializeComponent();
}
public void Log(string msg)
{
richTextBox1.BeginInvoke(new Action(
() =>
{
richTextBox1.Text += msg + "\n";
}));
}
public static string bufferincmessage;
public void AcceptSocketPackets(object client)
{
TcpClient tcpClient = (TcpClient)client;
NetworkStream clientStream = tcpClient.GetStream();
byte[] message = new byte[4096];
int bytesRead;
while (true)
{
bytesRead = 0;
try
{
//blocks until a client sends a message
bytesRead = clientStream.Read(message, 0, 4096);
}
catch (Exception ex)
{
//a socket error has occured
Log(ex.Message);
break;
}
if (bytesRead == 0)
{
//the client has disconnected from the server
Log("Client on " + tcpClient.Client.RemoteEndPoint + " has disconnected from the server");
break;
}
//message has successfully been received
UTF8Encoding encoder = new UTF8Encoding();
bufferincmessage = encoder.GetString(message, 0, bytesRead);
Log("Client from " + tcpClient.Client.RemoteEndPoint + ": " + bufferincmessage);
string stringToSend = "You sent me: " + bufferincmessage;
byte[] messageToSend = new byte[stringToSend.Length];
messageToSend = encoder.GetBytes(stringToSend);
clientStream.Write(messageToSend, 0, messageToSend.Length);
}
}
public void SocketAcceptCallback(IAsyncResult result)
{
TcpClient newClient = server.EndAcceptTcpClient(result);
Log("Accepted client on " + newClient.Client.RemoteEndPoint);
clientThreads.Add(new Thread(new ParameterizedThreadStart(AcceptSocketPackets)));
clientThreads[clientThreads.Count - 1].Start(newClient);
server.BeginAcceptTcpClient(SocketAcceptCallback, server);
}
private void Form1_Load(object sender, EventArgs e)
{
MainThread = Thread.CurrentThread;
clientThreads = new List<Thread>();
try
{
IPAddress localIP = null;
foreach (IPAddress addr in Dns.GetHostAddresses(Dns.GetHostName()))
{
if (addr.AddressFamily == AddressFamily.InterNetwork)
{
localIP = addr;
break;
}
}
localIP = IPAddress.Any;
// could also use this:
// server = new TcpListener(new IPEndPoint(IPAddress.Any, 1234));
server = new TcpListener(new IPEndPoint(localIP, 1234));
Log("Starting server on " + localIP + ":1234");
server.Start(6);
server.BeginAcceptTcpClient(SocketAcceptCallback, server);
Log("Started server on " + localIP + ":1234");
}
catch (Exception ex)
{
Log(ex.Message);
}
}
}
}

C++ is giving me problems like that. Try creating another project, paste the server code and build it as Release x86. If you change the build target and our problem is the same, windows firewall, even when turned off, won't allow the server or the client to run without any exception. If it doesn't work I might not know the answer.

Client send message server not received message in tcp/ip socket program

TCP/IP socket program client send text server receive and store database table. I'm righting code below but i have error text reeving time.
This is Client Side Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading.Tasks;
using System.IO;
namespace ClientApplication
{
class Client
{
static void Main(string[] args)
{
try
{
TcpClient tcpclnt = new TcpClient();
Console.WriteLine("Connecting.....");
//tcpclnt.Connect("162.144.85.232", 8080);
tcpclnt.Connect("162.144.85.232", 4489);
Console.WriteLine("Connected");
Console.Write("Enter the string to be Sent : ");
String str = Console.ReadLine();
Stream stm = tcpclnt.GetStream();
ASCIIEncoding asen = new ASCIIEncoding();
byte[] ba = asen.GetBytes(str);
System.Net.ServicePointManager.Expect100Continue = false;
Console.WriteLine("Sending.....");
stm.Write(ba, 0, ba.Length);
byte[] bb = new byte[100];
int k = stm.Read(bb, 0, 100);
for (int i = 0; i < k; i++)
Console.Write(Convert.ToChar(bb[i]));
Console.ReadLine();
tcpclnt.Close();
Console.ReadLine();
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
Console.ReadLine();
}
}
}
}
This Is Server Side Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
namespace ServerApplication
{
class Server
{
static void Main(string[] args)
{
try
{
IPAddress ipadd = IPAddress.Parse("192.168.1.7");
TcpListener list = new TcpListener(ipadd, 8080);
list.Start();
Console.WriteLine("The server is running at port 8080...");
Console.WriteLine("The Local End point Is:" + list.LocalEndpoint);
System.Net.ServicePointManager.Expect100Continue = false;
Socket s = list.AcceptSocket();
Console.WriteLine("Connections Accepted from:" + s.RemoteEndPoint);
byte[] b = new byte[100];
int k = s.Receive(b);
Console.WriteLine("Recived...");
for (int i = 0; i < k; i++)
Console.WriteLine(Convert.ToChar(b[i]));
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("The String Was Recived throw Server"));
Console.WriteLine("\n Sent Acknowlegment");
s.Close();
list.Stop();
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
}
}
}
}
I'm trying to execute this code i have error happen like this
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. Please resolve my issue .

There are a number of problems with the code you posted, but the one directly causing the behavior you're seeing is that the server closes the socket without waiting for the client to finish reading from the connection.
Look up "TCP graceful shutdown" for more information. In the meantime, the following is an improvement on the code you posted and won't have that problem:
Server code:
class Server
{
static void Main(string[] args)
{
try
{
TcpListener list = new TcpListener(IPAddress.Any, 8080);
list.Start();
Console.WriteLine("The server is running at port 8080...");
Console.WriteLine("The Local End point Is:" + list.LocalEndpoint);
Socket s = list.AcceptSocket();
Console.WriteLine("Connections Accepted from:" + s.RemoteEndPoint);
byte[] b = new byte[100];
int k;
while ((k = s.Receive(b)) > 0)
{
Console.WriteLine("Recived...");
Console.WriteLine(Encoding.ASCII.GetString(b, 0, k));
s.Send(Encoding.ASCII.GetBytes("The String Was Recived throw Server"));
Console.WriteLine("\n Sent Acknowlegment");
}
s.Shutdown(SocketShutdown.Both);
s.Close();
list.Stop();
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
}
}
}
Client code:
class Client
{
static void Main(string[] args)
{
try
{
TcpClient tcpclnt = new TcpClient();
Console.WriteLine("Connecting.....");
tcpclnt.Connect("192.168.1.7", 8080);
Console.WriteLine("Connected");
Console.Write("Enter the string to be Sent : ");
String str = Console.ReadLine();
Stream stm = tcpclnt.GetStream();
byte[] ba = Encoding.ASCII.GetBytes(str);
Console.WriteLine("Sending.....");
stm.Write(ba, 0, ba.Length);
tcpclnt.Client.Shutdown(SocketShutdown.Send);
byte[] bb = new byte[100];
int k;
while ((k = stm.Read(bb, 0, 100)) > 0)
{
Console.WriteLine(Encoding.ASCII.GetString(bb, 0, k));
}
Console.ReadLine();
tcpclnt.Close();
Console.ReadLine();
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
Console.ReadLine();
}
}
}
The key thing here is that both server and client continue to read from the connection until the remote end has, by calling Socket.Shutdown(), signaled that there is no more data to be read.
I also removed the use of the System.Net.ServicePointManager.Expect100Continue property, which had no effect in this code. That only affects programs that use the ServicePoint class and is not useful here.
It's also not clear to me why for the client you use the NetworkStream instead of just getting the Client socket and using it directly. The NetworkStream object is useful when wrapping your I/O in e.g. StreamReader and StreamWriter, but here you're just using Stream.Read() and Stream.Write(), which have the exact same semantics as Socket.Receive() and Socket.Send(), respectively. In any case, note that while you are using the NetworkStream object for the send and receive, you still need to access the underlying Socket instance directly to correctly initiate the graceful shutdown (the endpoint not initiating could just close the NetworkStream, since it doesn't have to shutdown until it's done both sending and receiving).
I also cleaned up the handling of the ASCII-encoded text a bit.

Server socket in Android, Client sockect C# not sending until socket close

I have a socket server in Android and a client Socket in C#. The socket stablish connection properly but the information is not sended until the socket is close. Ot seems that the information is in buffer and it is not sended until the resources must be released.
The server code is:
Socket socket = null;
DataInputStream dataInputStream = null;
DataOutputStream dataOutputStream = null;
try {
serverSocket = new ServerSocket(SocketServerPORT);
MainActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
info.setText("I'm waiting here: "+ serverSocket.getLocalPort());
}
});
while (true) {
socket = serverSocket.accept();
dataInputStream = new DataInputStream(socket.getInputStream());
dataOutputStream = new DataOutputStream(socket.getOutputStream());
String messageFromClient = "";
//If no message sent from client, this code will block the program
messageFromClient = dataInputStream.readLine();
count++;
message += "#" + count + " from " + socket.getInetAddress()+ ":" + socket.getPort() + "\n" + "Msg from client: " + messageFromClient + "\n";
MainActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
msg.setText(message);
}
});
And the client code is:
IPAddress host = IPAddress.Parse("192.168.1.129");
IPEndPoint hostep = new IPEndPoint(host, 8080);
Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
sock.Connect(hostep);
//sock.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.NoDelay, true);
}
catch (SocketException ex) {
Console.WriteLine("Problem connecting to host");
Console.WriteLine(e.ToString());
sock.Close();
return;
}
try
{
string theMessageToSend = "Que mierda es esta";
byte[] msg = Encoding.Unicode.GetBytes(theMessageToSend + "$");
sock.Send(msg);
//sock.Send(Encoding.ASCII.GetBytes("testing %"));
} catch (SocketException ex) {
Console.WriteLine("Problem sending data");
Console.WriteLine( e.ToString());
sock.Close();
return;
}
sock.Close();
I can not reach the line messageFromClient = dataInputStream.readLine(); in the server side until the sock.Close(); is executed in the client side.
Many thanks in advance!