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Save connected Socket in Dictionary

I'm trying to save a connected socket in a dictionary so my API doesn't have to create a new connection every time. My problem is that the socket gets disposed.
So when I call GetConnection() a second time socket.connected is false and socket.Available.Message is "Cannot access a disposed object. Object name: 'System.Net.Sockets.Socket'.".
public static class ModbusSocket
{
private static Dictionary<IPAddress, Socket> socketList;
public static Socket GetConnection(string server, int port)
{
if (socketList is null)
{
socketList = new Dictionary<IPAddress, Socket>();
}
IPAddress iPAddress = IPAddress.Parse(server);
if (socketList.ContainsKey(iPAddress))
{
var socket = socketList[iPAddress];
if (socket.Connected)
{
return socket;
}
else
{
socketList.Remove(iPAddress);
socket = new Socket(iPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipe = new IPEndPoint(iPAddress, port);
socket.Connect(ipe);
socketList.Add(iPAddress, socket);
return socket;
}
}
else
{
Socket socket = new Socket(iPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipe = new IPEndPoint(iPAddress, port);
socket.Connect(ipe);
socketList.Add(iPAddress, socket);
return socket;
}
}
}

OMG I found the issue...
I invoked it with using:
using (Socket s = ModbusSocket.GetConnection(hostIp, port))
{
var telegram = new Telegram();
telegram.Set(0, AddressConst.PositionWindow, 4);
var response = telegram.SendAndReceive(s);
var result = BitConverter.ToInt32(new byte[] { response.Byte19, response.Byte20, response.Byte21, response.Byte22 }, 0);
return result;
}

C# send custom socket string

I have this code:
public static List<Socket> samp = new List<Socket>();
IPHostEntry host = null;
Socket sock;
host = Dns.GetHostEntry(sending ip..);
foreach (IPAddress address in host.AddressList)
{
IPEndPoint ipe = new IPEndPoint(address, 7777);
sock = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
sock.Connect(ipe);
if (sock.Connected)
{
samp.Add(sock);
}
}
This code work's okay. It send's my ip. How it looks in console:
How can I send custom string? For example i'm tried this code:
if (sock.Connected)
{
byte[] msg = Encoding.UTF8.GetBytes("This is a test");
byte[] bytes = new byte[256];
int i = sock.Send(msg);
MessageBox.Show(string.Format("Sent {0} bytes.", i));
samp.Add(sock);
}
It shows message: Sent 14 bytes. But in the console nothing prints.. How can I send this text to console? I'm also tried this:
sock.Send(Encoding.UTF8.GetBytes("This is a test"));
And this not prints :(
Thanks in advance !

Send socket before closing

I have this code:
public static List<Socket> samp = new List<Socket>();
Socket connection/etc in form load..
IPHostEntry host = null;
Socket sock;
host = Dns.GetHostEntry(sending ip..);
foreach (IPAddress address in host.AddressList)
{
IPEndPoint ipe = new IPEndPoint(address, 7777);
sock = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
sock.Connect(ipe);
if (sock.Connected)
{
sock.SendTo(Encoding.UTF8.GetBytes("App starts"), ipe);
samp.Add(sock);
}
}
In form closing:
if (samp.Count > 0)
{
foreach (Socket socket in samp)
{
socket.Send(Encoding.UTF8.GetBytes("App closing"));
socket.Close();
}
}
And i'm getting error:
Cannot access a disposed object. Object name: 'System.Net.Sockets.Socket'
Thanks in advance!
P.S looks like socket.Close() works, but socket.Send nope :(

Why are clients connecting so slow?

I am trying to make a program in witch multiply clients will connect to the server. But i have a problem because when i try to connect more than 1 client at the same time, it takes a "long time" to do it.
i am using asynchronous way to connect:
public bool connect(string IP,int port)
{
try
{
if (m_clientSocket == null)
{
m_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress ip = IPAddress.Parse(IP.ToString());
int iPortNo = System.Convert.ToInt16(port.ToString());
IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
}
}catch()
{
return false;
}
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
Socket client = (Socket)ar.AsyncState;
if (m_clientSocket != null)
{
if (m_clientSocket.Connected)
{
client.EndConnect(ar);
// send next data here
}
else
{
client.EndConnect(ar);
m_clientSocket.Close();
m_clientSocket = null;
state = CONNECT_ERROR;
}
}
}
catch ()
{
}
}
For each client I want to connect I open a new class that includes two methods that you can see above. than with simple for loop I call methods one after another.
in Wireshark I observe the time that next needs to connect to a server is 0.1s witch I think is allot.
Any idea why does it take so long ?
Thanks for any kind of help.

Winforms C# app using sockets works under winXp, but throws error under Windows 7

Here's the properties and the method that connects.
protected Socket _socketConnection =
new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
private string _host = "";
private string _hostIpAddress = "";
private int _port = 0;
public void Connect()
{
// don't allow two connections
if (_socketConnection.Connected)
return;
// get the ip address from the hostname
IPHostEntry ipHostEntry = Dns.GetHostByName(_host);
_hostIpAddress = ipHostEntry.AddressList[0].ToString();
// create the socket endpoint
IPAddress ipAddress = IPAddress.Parse(_hostIpAddress);
IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, _port);
// connect
try
{
_socketConnection.Connect(ipEndPoint);
if (OnConnect != null)
OnConnect();
}
catch
{
throw;
}
}
When I run the app under Windows 7 I get the following error:
An unknown, invalid, or unsupported option or level was specified in a getsockopt or setsockopt call.
I've seen messages that talk about setting a particular option on the socket, but this is an app that has been working for years and is only happening when this app is installed on Windows 7.
Is there a compatibility flag to tweak or something?
Thanks!

Perhaps on Win7 you get a IPv6 as the _hostIpAddress. Try using something like this when instantiating the socket:
if(Socket.OSSupportsIPv6 && _hostIpAddress.AddressFamily == AddressFamily.InterNetworkV6)
{
// newer OS
_socketConnection = new Socket(
AddressFamily.InterNetworkV6,
SocketType.Stream,
ProtocolType.Tcp);
_socketConnection.SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only, 0);
} else {
// older OS
_socketConnection = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
}