Releasing a tcp port , asynchronous call

[EDN Admin]

Hi all,
<span style="font-family:Arial,Liberation Sans,DejaVu Sans,sans-serif; font-size:14px; line-height:18px; text-align:left I <span style="font-family:Arial,Liberation Sans,DejaVu Sans,sans-serif; font-size:14px; line-height:18px; text-align:left have
a TCP server which constantly receives tcp streams from different sources. I have a external event that triggers a stop, and when that happens, the TCP port need to be released. The code below works properly, except for the closure. The close is not releasing
the port and the tcp port is stuck in listening state. any help would be really great. Thank you.
<pre class="prettyprint using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Windows.Forms;


namespace TestTest
{

public class tcpserver
{

//State object for reading client data asynchronously
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 2097152;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();

}

public class AsynchronousSocketListener
{
public Form10 m_parent;
Socket parentlistener;

// Incoming data from client.
public static string data = null;

// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);

public AsynchronousSocketListener()
{
}

public void StartListening(Form10 frm10)
{
m_parent = frm10;

try
{
// Data buffer for incoming data.
byte[] bytes = new Byte[2097152];
int port = Convert.ToInt32(m_parent.textBox2.Text.Trim());
IPAddress ipv4 = IPAddress.Parse(m_parent.comboBox1.SelectedItem.ToString().Trim());
IPEndPoint localEndPoint = new IPEndPoint(ipv4, port);
// Create a TCP/IP socket.
parentlistener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
parentlistener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, false);
LingerOption lo = new LingerOption(false, 0);
parentlistener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Linger, lo);
//setting the array to have this ip and port
m_parent.m_parent.setUsedIPport(m_parent.comboBox1.SelectedItem.ToString().Trim() + ":" + m_parent.textBox2.Text.Trim());


// Bind the socket to the local endpoint and listen for incoming connections.

try
{
parentlistener.Bind(localEndPoint); // THIS IS THE PORT I WOULD LIKE TO RELEASE ON AN EXTERNAL TRIGGER
parentlistener.Listen(100);

while (m_parent.getStopState() == false)
{
// MessageBox.Show("L");

allDone.Reset();

//// Start an asynchronous socket to listen for connections.
parentlistener.BeginAccept(new AsyncCallback(AcceptCallback), parentlistener);

}

}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}


}
catch (Exception) { MessageBox.Show("Error binding to tcp port", "ERROR"); return; }


}

public void AcceptCallback(IAsyncResult ar)
{
try
{
// Signal the main thread to continue.
allDone.Set();

// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
LingerOption lo = new LingerOption(false, 0);
handler.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Linger, lo);

// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;


handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);

}
catch (Exception er) { //MessageBox.Show(er.ToString());
}
}

public void ReadCallback(IAsyncResult ar)
{

try
{


String line = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;

string temporaryString = "";
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);

if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

line = state.sb.ToString(); //this goes into an external store, code is not here

handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);

}
}

}
catch (Exception er) { //MessageBox.Show(er.ToString());
}
}

public void stopListener()
{

try
{


parentlistener.Shutdown(SocketShutdown.Both);
//parentlistener.Disconnect(true);
parentlistener.Close(); //PROBLEM !!! code is not releasing the port, the tcp port continues to remain in the listening state.
parentlistener.Dispose();
}
catch (Exception Ex) { //MessageBox.Show(Ex.ToString());
}

}

}

}
}[/code]


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