When the Client tries to connect to a disconnected IP address, there is a long timeout over 15 seconds... How can we reduce this timeout? What is the method to configure it?
The code I'm using to set up a socket connection is as following:
try
{
m_clientSocket = new Socket(
AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);
IPAddress ip = IPAddress.Parse(serverIp);
int iPortNo = System.Convert.ToInt16(serverPort);
IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);
m_clientSocket.Connect(ipEnd);
if (m_clientSocket.Connected)
{
lb_connectStatus.Text = "Connection Established";
WaitForServerData();
}
}
catch (SocketException se)
{
lb_connectStatus.Text = "Connection Failed";
MessageBox.Show(se.Message);
}
I found this. Simpler than the accepted answer, and works with .NET Framework v2
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// Connect using a timeout (5 seconds)
IAsyncResult result = socket.BeginConnect( sIP, iPort, null, null );
bool success = result.AsyncWaitHandle.WaitOne( 5000, true );
if ( socket.Connected )
{
socket.EndConnect( result );
}
else
{
// NOTE, MUST CLOSE THE SOCKET
socket.Close();
throw new ApplicationException("Failed to connect server.");
}
//...
My take:
public static class SocketExtensions
{
/// <summary>
/// Connects the specified socket.
/// </summary>
/// <param name="socket">The socket.</param>
/// <param name="endpoint">The IP endpoint.</param>
/// <param name="timeout">The timeout.</param>
public static void Connect(this Socket socket, EndPoint endpoint, TimeSpan timeout)
{
var result = socket.BeginConnect(endpoint, null, null);
bool success = result.AsyncWaitHandle.WaitOne(timeout, true);
if (success)
{
socket.EndConnect(result);
}
else
{
socket.Close();
throw new SocketException(10060); // Connection timed out.
}
}
}
I just wrote an extension class in order to allow timeouts in connections. Use it exactly as you would use the standard Connect() methods, with an extra parameter named timeout.
using System;
using System.Net;
using System.Net.Sockets;
/// <summary>
/// Extensions to Socket class
/// </summary>
public static class SocketExtensions
{
/// <summary>
/// Connects the specified socket.
/// </summary>
/// <param name="socket">The socket.</param>
/// <param name="host">The host.</param>
/// <param name="port">The port.</param>
/// <param name="timeout">The timeout.</param>
public static void Connect(this Socket socket, string host, int port, TimeSpan timeout)
{
AsyncConnect(socket, (s, a, o) => s.BeginConnect(host, port, a, o), timeout);
}
/// <summary>
/// Connects the specified socket.
/// </summary>
/// <param name="socket">The socket.</param>
/// <param name="addresses">The addresses.</param>
/// <param name="port">The port.</param>
/// <param name="timeout">The timeout.</param>
public static void Connect(this Socket socket, IPAddress[] addresses, int port, TimeSpan timeout)
{
AsyncConnect(socket, (s, a, o) => s.BeginConnect(addresses, port, a, o), timeout);
}
/// <summary>
/// Asyncs the connect.
/// </summary>
/// <param name="socket">The socket.</param>
/// <param name="connect">The connect.</param>
/// <param name="timeout">The timeout.</param>
private static void AsyncConnect(Socket socket, Func<Socket, AsyncCallback, object, IAsyncResult> connect, TimeSpan timeout)
{
var asyncResult = connect(socket, null, null);
if (!asyncResult.AsyncWaitHandle.WaitOne(timeout))
{
try
{
socket.EndConnect(asyncResult);
}
catch (SocketException)
{ }
catch (ObjectDisposedException)
{ }
}
}
it might be too late but there is neat solution based on Task.WaitAny (c# 5 +) :
public static bool ConnectWithTimeout(this Socket socket, string host, int port, int timeout)
{
bool connected = false;
Task result = socket.ConnectAsync(host, port);
int index = Task.WaitAny(new[] { result }, timeout);
connected = socket.Connected;
if (!connected) {
socket.Close();
}
return connected;
}
I dont program in C# but in C, we solve the same problem by making the socket non-blocking and then putting the fd in a select/poll loop with a timeout value equal to the amount of time we are willing to wait for the connect to succeed.
I found this for Visual C++ and the explanation there also bends towards the select/poll mechanism I explained before.
In my experience, you cannot change connect timeout values per socket. You change it for all (by tuning OS parameters).
I solved the problem by using Socket.ConnectAsync Method instead of Socket.Connect Method.
After invoking the Socket.ConnectAsync(SocketAsyncEventArgs), start a timer (timer_connection), if time is up, check whether socket connection is connected (if(m_clientSocket.Connected)), if not, pop up timeout error.
private void connect(string ipAdd,string port)
{
try
{
SocketAsyncEventArgs e=new SocketAsyncEventArgs();
m_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress ip = IPAddress.Parse(serverIp);
int iPortNo = System.Convert.ToInt16(serverPort);
IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);
//m_clientSocket.
e.RemoteEndPoint = ipEnd;
e.UserToken = m_clientSocket;
e.Completed+=new EventHandler<SocketAsyncEventArgs>(e_Completed);
m_clientSocket.ConnectAsync(e);
if (timer_connection != null)
{
timer_connection.Dispose();
}
else
{
timer_connection = new Timer();
}
timer_connection.Interval = 2000;
timer_connection.Tick+=new EventHandler(timer_connection_Tick);
timer_connection.Start();
}
catch (SocketException se)
{
lb_connectStatus.Text = "Connection Failed";
MessageBox.Show(se.Message);
}
}
private void e_Completed(object sender,SocketAsyncEventArgs e)
{
lb_connectStatus.Text = "Connection Established";
WaitForServerData();
}
private void timer_connection_Tick(object sender, EventArgs e)
{
if (!m_clientSocket.Connected)
{
MessageBox.Show("Connection Timeout");
//m_clientSocket = null;
timer_connection.Stop();
}
}
Check this out on MSDN. It does not appear that you can do this with the implemented properties in the Socket class.
The poster on MSDN actually solved his problem using threading. He had a main thread which called out to other threads which run the connection code for a couple seconds and then check the Connected property of the socket:
I created another method wich actually
connected the socket ... had the main
thread sleep for 2 seconds and then
check on the connecting method (wich
is run in a separate thread) if the
socket was connected good otherwise
throw an exception "Timed out " and
that;s all. Thanks again for the
repleies.
What are you trying to do, and why can't it wait for 15-30 seconds before timing out?
I had the Same problem when connecting to a Socket and I came up with the below solution ,It works Fine for me.
`
private bool CheckConnectivityForProxyHost(string hostName, int port)
{
if (string.IsNullOrEmpty(hostName))
return false;
bool isUp = false;
Socket testSocket = null;
try
{
testSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress ip = null;
if (testSocket != null && NetworkingCollaboratorBase.GetResolvedConnecionIPAddress(hostName, out ip))//Use a method to resolve your IP
{
IPEndPoint ipEndPoint = new IPEndPoint(ip, port);
isUp = false;
//time out 5 Sec
CallWithTimeout(ConnectToProxyServers, 5000, testSocket, ipEndPoint);
if (testSocket != null && testSocket.Connected)
{
isUp = true;
}
}
}
}
catch (Exception ex)
{
isUp = false;
}
finally
{
try
{
if (testSocket != null)
{
testSocket.Shutdown(SocketShutdown.Both);
}
}
catch (Exception ex)
{
}
finally
{
if (testSocket != null)
testSocket.Close();
}
}
return isUp;
}
private void CallWithTimeout(Action<Socket, IPEndPoint> action, int timeoutMilliseconds, Socket socket, IPEndPoint ipendPoint)
{
try
{
Action wrappedAction = () =>
{
action(socket, ipendPoint);
};
IAsyncResult result = wrappedAction.BeginInvoke(null, null);
if (result.AsyncWaitHandle.WaitOne(timeoutMilliseconds))
{
wrappedAction.EndInvoke(result);
}
}
catch (Exception ex)
{
}
}
private void ConnectToProxyServers(Socket testSocket, IPEndPoint ipEndPoint)
{
try
{
if (testSocket == null || ipEndPoint == null)
return;
testSocket.Connect(ipEndPoint);
}
catch (Exception ex)
{
}
}
I worked with Unity and had some problem with the BeginConnect and other async methods from socket.
There is something than I don't understand but the code samples before doesn't work for me.
So I wrote this piece of code to make it work. I test it on an adhoc network with android and pc, also in local on my computer. Hope it can help.
using System.Net.Sockets;
using System.Threading;
using System.Net;
using System;
using System.Diagnostics;
class ConnexionParameter : Guardian
{
public TcpClient client;
public string address;
public int port;
public Thread principale;
public Thread thisthread = null;
public int timeout;
private EventWaitHandle wh = new AutoResetEvent(false);
public ConnexionParameter(TcpClient client, string address, int port, int timeout, Thread principale)
{
this.client = client;
this.address = address;
this.port = port;
this.principale = principale;
this.timeout = timeout;
thisthread = new Thread(Connect);
}
public void Connect()
{
WatchDog.Start(timeout, this);
try
{
client.Connect(IPAddress.Parse(address), port);
}
catch (Exception)
{
UnityEngine.Debug.LogWarning("Unable to connect service (Training mode? Or not running?)");
}
OnTimeOver();
//principale.Resume();
}
public bool IsConnected = true;
public void OnTimeOver()
{
try
{
if (!client.Connected)
{
/*there is the trick. The abort method from thread doesn't
make the connection stop immediately(I think it's because it rise an exception
that make time to stop). Instead I close the socket while it's trying to
connect , that make the connection method return faster*/
IsConnected = false;
client.Close();
}
wh.Set();
}
catch(Exception)
{
UnityEngine.Debug.LogWarning("Connexion already closed, or forcing connexion thread to end. Ignore.");
}
}
public void Start()
{
thisthread.Start();
wh.WaitOne();
//principale.Suspend();
}
public bool Get()
{
Start();
return IsConnected;
}
}
public static class Connexion
{
public static bool Connect(this TcpClient client, string address, int port, int timeout)
{
ConnexionParameter cp = new ConnexionParameter(client, address, port, timeout, Thread.CurrentThread);
return cp.Get();
}
//http://stackoverflow.com/questions/19653588/timeout-at-acceptsocket
public static Socket AcceptSocket(this TcpListener tcpListener, int timeoutms, int pollInterval = 10)
{
TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutms);
var stopWatch = new Stopwatch();
stopWatch.Start();
while (stopWatch.Elapsed < timeout)
{
if (tcpListener.Pending())
return tcpListener.AcceptSocket();
Thread.Sleep(pollInterval);
}
return null;
}
}
and there a very simple watchdog on C# to make it work:
using System.Threading;
public interface Guardian
{
void OnTimeOver();
}
public class WatchDog {
int m_iMs;
Guardian m_guardian;
public WatchDog(int a_iMs, Guardian a_guardian)
{
m_iMs = a_iMs;
m_guardian = a_guardian;
Thread thread = new Thread(body);
thread.Start(this);
}
private void body(object o)
{
WatchDog watchdog = (WatchDog)o;
Thread.Sleep(watchdog.m_iMs);
watchdog.m_guardian.OnTimeOver();
}
public static void Start(int a_iMs, Guardian a_guardian)
{
new WatchDog(a_iMs, a_guardian);
}
}
This is like FlappySock's answer, but I added a callback to it because I didn't like the layout and how the Boolean was getting returned. In the comments of that answer from Nick Miller:
In my experience, if the end point can be reached, but there is no server on the endpoint able to receive the connection, then AsyncWaitHandle.WaitOne will be signaled, but the socket will remain unconnected
So to me, it seems relying on what is returned can be dangerous - I prefer to use socket.Connected. I set a nullable Boolean and update it in the callback function. I also found it doesn't always finish reporting the result before returning to the main function - I handle for that, too, and make it wait for the result using the timeout:
private static bool? areWeConnected = null;
private static bool checkSocket(string svrAddress, int port)
{
IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse(svrAddress), port);
Socket socket = new Socket(endPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
int timeout = 5000; // int.Parse(ConfigurationManager.AppSettings["socketTimeout"].ToString());
int ctr = 0;
IAsyncResult ar = socket.BeginConnect(endPoint, Connect_Callback, socket);
ar.AsyncWaitHandle.WaitOne( timeout, true );
// Sometimes it returns here as null before it's done checking the connection
// No idea why, since .WaitOne() should block that, but it does happen
while (areWeConnected == null && ctr < timeout)
{
Thread.Sleep(100);
ctr += 100;
} // Given 100ms between checks, it allows 50 checks
// for a 5 second timeout before we give up and return false, below
if (areWeConnected == true)
{
return true;
}
else
{
return false;
}
}
private static void Connect_Callback(IAsyncResult ar)
{
areWeConnected = null;
try
{
Socket socket = (Socket)ar.AsyncState;
areWeConnected = socket.Connected;
socket.EndConnect(ar);
}
catch (Exception ex)
{
areWeConnected = false;
// log exception
}
}
Related: How to check if I'm connected?
I have tried with dotnet 6, and after accepting a connection dotnet allows you to set the timeout.
Socket clientSocket = listener.Accept();
clientSocket.ReceiveTimeout = 1000;
and the you have to manage with Receive
try
{
int numByte = clientSocket.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, numByte);
break;
}
catch (System.Net.Sockets.SocketException e)
{
clientSocket.Shutdown(SocketShutdown.Both);
clientSocket.Close();
goto NewSocket;
}
Source: Microsoft
There should be a ReceiveTimeout property in the Socket class.
Socket.ReceiveTimeout Property
Related
This is my scenario:
Client :
Send xml data in pieces continuously 24/7 - (It is working fine and it is not in my control).
Server - My Code:
1. Listen continuously.
2. Receive the incoming message, buffer it and create valid xml from buffer.
3. Send it to the MSMQ ( Host will do this )
I wrote a tcp server code (adding pieces of code from google), which will be hosted in windows service. Everything works fine when I run the service in local but when I place it PROD, it listens upto 73K messages and it stops receiving. It is not throwing any exception. It just blocks at BeginReceive function. I have tried using ReceiveTimeOut also. I have seen netstat also and the connections is still in established stat.
When I restart the service, it again works fine. Here I am posting my server code. Please help on this.
StringBuilder content = new StringBuilder();
public event MessageReceiveEventHandler MessageReceived;
// An ArrayList is used to keep track of worker sockets that are designed
// to communicate with each connected client. Make it a synchronized ArrayList
// For thread safety
private System.Collections.ArrayList workerSocketList =
ArrayList.Synchronized(new System.Collections.ArrayList());
private int m_clientCount = 0;
private Socket m_mainSocket = null;
private AsyncCallback ReadCallback;
private AsyncCallback ConnectionCallback;
public MedDeviceListener(string ipAddress, int port, int maxConnections=100)
{
ProfileProvider.Instance.LogInformationIf(_debug);
this._port = port;
this._ipAddress = ipAddress;
this._maxConnections = maxConnections;
ReadCallback = new AsyncCallback(Receive_handler);
ConnectionCallback = new AsyncCallback(Connection_handler);
lenghtofStartMsg = header.Length;
lengthOfEndMsg = footer.Length;
}
public void Start()
{
ProfileProvider.Instance.LogInformationIf(_debug);
// Data buffer for incoming data.
byte[] bytes = new Byte[_bufferSize];
// Establish the local endpoint for the socket.
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Parse(_ipAddress), _port);
// Create a TCP/IP socket.
m_mainSocket = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and listen for incoming connections.
try
{
m_mainSocket.Bind(localEndPoint);
m_mainSocket.Listen(100);
InstrumentationProvider.Instance.LogInformation("MedDeviceListener successfully connected to IP:" + _ipAddress+"\nPort :"+_port);
m_mainSocket.BeginAccept(ConnectionCallback, m_mainSocket);
}
catch (Exception e)
{
InstrumentationProvider.Instance.LogException("MedDeviceListener.Start", e);
throw e;
}
}
private void Connection_handler(IAsyncResult ar)
{
try
{
ProfileProvider.Instance.LogInformationIf(_debug);
Socket listener = (Socket)ar.AsyncState;
Socket workerSocket = listener.EndAccept(ar);
// Now increment the client count for this client
// in a thread safe manner
Interlocked.Increment(ref m_clientCount);
// Add the workerSocket reference to our ArrayList
workerSocketList.Add(workerSocket);
SendConnectedAck(_clientConnectAckMessage, m_clientCount);
WaitForData(workerSocket, m_clientCount);
//Resume the listening callback loop
listener.BeginAccept(Connection_handler, listener);
}
catch (ObjectDisposedException)
{
InstrumentationProvider.Instance.LogInformation("The listener socket has been closed");
}
catch (Exception ex)
{
InstrumentationProvider.Instance.LogException("Connection_handler", ex);
throw;
}
}
private void Receive_handler(IAsyncResult ar)
{
ProfileProvider.Instance.LogInformationIf(_debug);
StateObject state = (StateObject)ar.AsyncState;
try
{
// Retrieve the state object and the handler socket
// from the asynchronous state object.
Socket workSocket = state.workSocket;
// Read data from the client socket.
int bytesRead = workSocket.EndReceive(ar);
if (bytesRead > 0)
{
//InstrumentationProvider.Instance.LogInformationIf(_debug, bytesRead+" read..");
// There might be more data, so parse the data received so far.
string data= Encoding.ASCII.GetString(state.buffer, 0, bytesRead);
try
{
ParseIncomingMessage(data, workSocket);
}
catch(Exception parseEx)
{
content.Clear();
InstrumentationProvider.Instance.LogException("ParseIncomingMessage", parseEx);
}
}
WaitForData(state.workSocket, state.clientNumber);
}
catch (ObjectDisposedException)
{
InstrumentationProvider.Instance.LogInformation("Receive_handler: The listener socket has been closed");
}
catch (SocketException se)
{
//close the existing connection
CloseSockets();
//restart it again
this.Start();
}
}
private void WaitForData(Socket workerSocket, int clientNumber)
{
ProfileProvider.Instance.LogInformationIf(_debug);
try
{
StateObject theSocPkt = new StateObject(workerSocket, clientNumber);
workerSocket.ReceiveTimeout = 2000;
workerSocket.BeginReceive(theSocPkt.buffer, 0,
theSocPkt.buffer.Length,
SocketFlags.None,
Receive_handler,
theSocPkt);
}
catch(TimeoutException ex)
{
InstrumentationProvider.Instance.LogException("WaitForData - TimeOutException", ex);
}
catch (SocketException se)
{
InstrumentationProvider.Instance.LogException("MedDeviceListener.WaitForData", se);
//close the existing connection
CloseSockets();
//restart it again
this.Start();
}
catch (Exception ex)
{
InstrumentationProvider.Instance.LogException("WaitForData",ex);
//close the existing connection
CloseSockets();
//restart it again
this.Start();
}
}
private void ParseIncomingMessage(string msg,Socket wrkSocket)
{
Socket workSocket = wrkSocket;
bool hasStartTag = isMsgContainsStartTag(msg);
bool hasEndTag = isMsgContainsEndTag(msg);
int startTagIndex = indexOfStartTag(msg);
int endTagIndex = indexOfEndTag(msg);
// If the incomming message dont have either start or end tag
if (hasStartTag == false && hasEndTag == false)
{
content.Append(msg);
}
//check for the starttag first
//if message contains startTag
else if (hasStartTag)
{
if (startTagIndex != 0)//there is something before starttag
{
string subStr = msg.Substring(0, startTagIndex);
content.Append(subStr);
//Check and send the content
CheckSendMessage(workSocket);
//Parse the remaining message from start tag to end of the message
ParseIncomingMessage(msg.Substring(startTagIndex, msg.Length - subStr.Length), wrkSocket);
}
else if (startTagIndex == 0)
{
content.Clear();
if (hasEndTag)
{
int endOfEndTag = endTagIndex + lengthOfEndMsg;
string subStr = msg.Substring(0, endOfEndTag); //message statrs with start tag and ends contains full end tag so first get that string and send that.
content.Append(subStr);
CheckSendMessage(workSocket);
//Parse the remaining message from endtag+1 to end
ParseIncomingMessage(msg.Substring(endOfEndTag, msg.Length - endOfEndTag), wrkSocket);
}
else
{
content.Append(msg);
}
}
}
//if message contains EndTag ALONE
else if (hasEndTag)
{
int endOfEndTag = endTagIndex + lengthOfEndMsg;
string subStr = msg.Substring(0, endOfEndTag);
content.Append(subStr);
CheckSendMessage(workSocket);
//Parse remaining message after end tag
ParseIncomingMessage(msg.Substring(endOfEndTag, msg.Length - endOfEndTag), wrkSocket);
}
}
private void CheckSendMessage(Socket workSocket)
{
string msg=content.ToString().Trim();
//if content contains both start and end tag then send the content
if (isMsgContainsStartTag(msg) && isMsgContainsEndTag(msg) &&
indexOfStartTag(msg) == 0 && indexOfEndTag(msg) + lengthOfEndMsg == msg.Length)
{
//Send the message
using (MedDeviceListenerEventArgs e = new MedDeviceListenerEventArgs(msg))
{
OnReceiveComplete(e);
SendReceiveAck(workSocket, _receiveAckMessage);
}
}
}
private void SendReceiveAck(Socket handler, String data)
{
try
{
ProfileProvider.Instance.LogInformationIf(_debug);
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
handler.Send(byteData);
InstrumentationProvider.Instance.LogInformationIf(_debug, "Message received acknowledgement:" + _receiveAckMessage + " has been sent successfully");
}
catch (Exception ex)
{
InstrumentationProvider.Instance.LogException("SendReceiveAck", ex);
}
}
private void SendConnectedAck(string msg, int clientNumber)
{
ProfileProvider.Instance.LogInformationIf(_debug);
try
{
// Convert the reply to byte array
byte[] byData = System.Text.Encoding.ASCII.GetBytes(msg);
Socket workerSocket = (Socket)workerSocketList[clientNumber - 1];
workerSocket.Send(byData);
InstrumentationProvider.Instance.LogInformationIf(_debug, "Client Connected acknowledgement:" + _clientConnectAckMessage + " has been sent successfully");
}
catch (Exception ex)
{
InstrumentationProvider.Instance.LogException("SendConnectedAck", ex);
throw;
}
}
public void CloseSockets()
{
try
{
ProfileProvider.Instance.LogInformationIf(_debug);
if (m_mainSocket != null)
{
if (m_mainSocket.Connected)
{
m_mainSocket.Shutdown(SocketShutdown.Both);
m_mainSocket.Close();
m_mainSocket = null;
}
}
Socket workerSocket = null;
for (int i = 0; i < workerSocketList.Count; i++)
{
workerSocket = (Socket)workerSocketList[i];
if (workerSocket != null)
{
workerSocket.Shutdown(SocketShutdown.Both);
workerSocket.Close();
workerSocket = null;
}
}
}
catch(Exception ex)
{
InstrumentationProvider.Instance.LogException("CloseSockets",ex);
}
}
protected virtual void OnReceiveComplete(MedDeviceListenerEventArgs e)
{
if (MessageReceived != null)
{
MessageReceived(this, e);
}
}
private int indexOfStartTag(string msg)
{
return msg.IndexOf(header);
}
private int indexOfEndTag(string msg)
{
return msg.IndexOf(footer);
}
private bool isMsgContainsStartTag(string msg)
{
return msg.Contains(header);
}
private bool isMsgContainsEndTag(string msg)
{
return msg.Contains(footer);
}
public delegate void MessageReceiveEventHandler(object sender,MedDeviceListenerEventArgs e);
public class MedDeviceListenerEventArgs : EventArgs,IDisposable
{
private string _receivedData;
public MedDeviceListenerEventArgs(string receivedData)
{
_receivedData = receivedData;
}
public string ReceivedData
{
get
{
return _receivedData;
}
}
public void Dispose()
{ }
}
}
I have read similar posts, tried everything but with no luck. Please help :)
Thanks
-MM
I have managed to create a Server/Client chat system, where the client sends a message to the server and the the server sends the message to all the clients.
I want to extend this so that the Server compares the messages and then sends a message to the client.
For Example: If client 1 sends 10 and client 2 sends 20 the server will compare these and the server will send a message saying 20 is more than 10.
Is this possible to do? And if so how?
Server Code:
namespace Server
{
public partial class Form1 : Form
{
private const int m_iMaxConnections = 2;
struct Connection_Struct // Define a structure to hold details about a single connection
{
public Socket ClientSpecific_Socket;
public bool bInUse;
};
Socket m_ListenSocket;
Socket m_SendSocket;
Connection_Struct[] m_Connection_Array = new Connection_Struct[m_iMaxConnections]; // Define an array to hold a number of connections
System.Net.IPEndPoint m_LocalIPEndPoint;
static int m_iNumberOfConnectedClients;
private static System.Windows.Forms.Timer m_CommunicationActivity_Timer;
public Form1()
{
InitializeComponent();
Initialise_ConnectionArray();
m_CommunicationActivity_Timer = new System.Windows.Forms.Timer(); // Check for communication activity on Non-Blocking sockets every 200ms
m_CommunicationActivity_Timer.Tick += new EventHandler(OnTimedEvent_PeriodicCommunicationActivityCheck); // Set event handler method for timer
m_CommunicationActivity_Timer.Interval = 100; // Timer interval is 1/10 second
m_CommunicationActivity_Timer.Enabled = false;
string szLocalIPAddress = GetLocalIPAddress_AsString(); // Get local IP address as a default value
txtIPAddress.Text = szLocalIPAddress; // Place local IP address in IP address field
txtPort.Text = "8000"; // Default port number
m_iNumberOfConnectedClients = 0;
txtClientNo.Text = System.Convert.ToString(m_iNumberOfConnectedClients);
try
{ // Create the Listen socket, for TCP use
m_ListenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
m_ListenSocket.Blocking = false;
m_SendSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Tcp);
}
catch (SocketException se)
{ // If an exception occurs, display an error message
MessageBox.Show(se.Message);
}
}
private void Initialise_ConnectionArray()
{
int iIndex;
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
m_Connection_Array[iIndex].bInUse = false;
}
}
private void btnEnableServer_Click(object sender, EventArgs e)
{
// Bind to the selected port and start listening / receiving
try
{
// Get the Port number from the appropriate text box
String szPort = txtPort.Text;
int iPort = System.Convert.ToInt16(szPort, 10);
// Create an Endpoint that will cause the listening activity to apply to all the local node's interfaces
m_LocalIPEndPoint = new System.Net.IPEndPoint(IPAddress.Any, iPort);
// Bind to the local IP Address and selected port
m_ListenSocket.Bind(m_LocalIPEndPoint);
txtLog.Text = "Bind succeded";
// Prevent any further changes to the port number
txtPort.ReadOnly = true;
}
catch // Catch any errors
{ // If an exception occurs, display an error message
txtLog.Text = "Bind failed";
}
try
{
txtLog.Text = "Listening";
m_ListenSocket.Listen(2); // Listen for connections, with a backlog / queue maximum of 2
}
catch (SocketException se)
{
// If an exception occurs, display an error message
MessageBox.Show(se.Message);
}
catch // Silently handle any other exception
{
}
m_CommunicationActivity_Timer.Start(); // Start the timer to perform periodic checking for connection requests
txtLog.Text = "Accepting (waiting for connection attempt)";
btnEnableServer.Enabled = false;
}
private void OnTimedEvent_PeriodicCommunicationActivityCheck(Object myObject, EventArgs myEventArgs)
{ // Periodic check whether a connection request is pending or a message has been received on a connected socket
// First, check for pending connection requests
int iIndex;
iIndex = GetnextAvailable_ConnectionArray_Entry(); // Find an available array entry for next connection request
if (-1 != iIndex)
{ // Only continue with Accept if there is an array entry available to hold the details
try
{
m_Connection_Array[iIndex].ClientSpecific_Socket = m_ListenSocket.Accept(); // Accept a connection (if pending) and assign a new socket to it (AcceptSocket)
// Will 'catch' if NO connection was pending, so statements below only occur when a connection WAS pending
m_Connection_Array[iIndex].bInUse = true;
m_Connection_Array[iIndex].ClientSpecific_Socket.Blocking = false; // Make the new socket operate in non-blocking mode
m_iNumberOfConnectedClients++;
txtClientNo.Text = System.Convert.ToString(m_iNumberOfConnectedClients);
txtLog.Text = "A new client connected";
SendUpdateMesageToAllConnectedclients();
}
catch (SocketException se) // Handle socket-related exception
{ // If an exception occurs, display an error message
if (10053 == se.ErrorCode || 10054 == se.ErrorCode) // Remote end closed the connection
{
CloseConnection(iIndex);
}
else if (10035 != se.ErrorCode)
{ // Ignore error messages relating to normal behaviour of non-blocking sockets
MessageBox.Show(se.Message);
}
}
catch // Silently handle any other exception
{
}
}
// Second, check for received messages on each connected socket
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
if (true == m_Connection_Array[iIndex].bInUse)
{
try
{
EndPoint localEndPoint = (EndPoint)m_LocalIPEndPoint;
byte[] ReceiveBuffer = new byte[1024];
int iReceiveByteCount;
iReceiveByteCount = m_Connection_Array[iIndex].ClientSpecific_Socket.ReceiveFrom(ReceiveBuffer, ref localEndPoint);
string szReceivedMessage;
if (0 < iReceiveByteCount)
{ // Copy the number of bytes received, from the message buffer to the text control
szReceivedMessage = Encoding.ASCII.GetString(ReceiveBuffer, 0, iReceiveByteCount);
if ("QuitConnection" == szReceivedMessage)
{
CloseConnection(iIndex);
}
else
{
txtLog.AppendText(szReceivedMessage + Environment.NewLine);
// Send message to each connected client.
// int iIndex2;
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
if (true == m_Connection_Array[iIndex].bInUse)
{
string szMessage;
szMessage = szReceivedMessage;
txtLog.Text = m_Connection_Array[m_iMaxConnections].ToString();
byte[] SendMessage = System.Text.Encoding.ASCII.GetBytes(szMessage);
m_Connection_Array[iIndex].ClientSpecific_Socket.Send(SendMessage, SocketFlags.None);
}
}
}
}
}
catch (SocketException se) // Handle socket-related exception
{ // If an exception occurs, display an error message
if (10053 == se.ErrorCode || 10054 == se.ErrorCode) // Remote end closed the connection
{
CloseConnection(iIndex);
}
else if (10035 != se.ErrorCode)
{ // Ignore error messages relating to normal behaviour of non-blocking sockets
MessageBox.Show(se.Message);
}
}
catch // Silently handle any other exception
{
}
}
}
}
private void SendUpdateMesageToAllConnectedclients()
{ // Send message to each connected client informing of the total number of connected clients
int iIndex;
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
if (true == m_Connection_Array[iIndex].bInUse)
{
string szMessage;
if (1 == m_iNumberOfConnectedClients)
{
szMessage = string.Format("There is now {0} client connected", m_iNumberOfConnectedClients);
}
else
{
szMessage = string.Format("There are now {0} clients connected", m_iNumberOfConnectedClients);
}
byte[] SendMessage = System.Text.Encoding.ASCII.GetBytes(szMessage);
m_Connection_Array[iIndex].ClientSpecific_Socket.Send(SendMessage, SocketFlags.None);
}
}
}
private void CloseConnection(int iIndex)
{
try
{
m_Connection_Array[iIndex].bInUse = false;
m_Connection_Array[iIndex].ClientSpecific_Socket.Shutdown(SocketShutdown.Both);
m_Connection_Array[iIndex].ClientSpecific_Socket.Close();
m_iNumberOfConnectedClients--;
txtClientNo.Text = System.Convert.ToString(m_iNumberOfConnectedClients);
txtLog.Text = "A Connection was closed";
SendUpdateMesageToAllConnectedclients();
}
catch // Silently handle any exceptions
{
}
}
private void Close_And_Quit()
{ // Close the sockets and exit the application
try
{
m_ListenSocket.Close();
}
catch
{
}
try
{
int iIndex;
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
m_Connection_Array[iIndex].ClientSpecific_Socket.Shutdown(SocketShutdown.Both);
m_Connection_Array[iIndex].ClientSpecific_Socket.Close();
}
}
catch
{
}
try
{
Close();
}
catch
{
}
}
public string GetLocalIPAddress_AsString()
{
string szHost = Dns.GetHostName();
string szLocalIPaddress = "127.0.0.1"; // Default is local loopback address
IPHostEntry IPHost = Dns.GetHostEntry(Dns.GetHostName());
foreach (IPAddress IP in IPHost.AddressList)
{
if (IP.AddressFamily == AddressFamily.InterNetwork) // Match only the IPv4 address
{
szLocalIPaddress = IP.ToString();
break;
}
}
return szLocalIPaddress;
}
private int GetnextAvailable_ConnectionArray_Entry()
{
int iIndex;
for (iIndex = 0; iIndex < m_iMaxConnections; iIndex++)
{
if (false == m_Connection_Array[iIndex].bInUse)
{
return iIndex; // Return the index value of the first not-in-use entry found
}
}
return -1; // Signal that there were no available entries
}
}
}
Client Code:
namespace Client
{
public partial class Form1 : Form
{
Socket m_ClientSocket;
System.Net.IPEndPoint m_remoteEndPoint;
IPEndPoint m_localIPEndPoint;
Socket m_ReceiveSocket;
private static System.Windows.Forms.Timer m_CommunicationActivity_Timer;
public Form1()
{
InitializeComponent();
m_CommunicationActivity_Timer = new System.Windows.Forms.Timer(); // Check for communication activity on Non-Blocking sockets every 200ms
m_CommunicationActivity_Timer.Tick += new EventHandler(OnTimedEvent_PeriodicCommunicationActivityCheck); // Set event handler method for timer
m_CommunicationActivity_Timer.Interval = 100; // Timer interval is 1/10 second
m_CommunicationActivity_Timer.Enabled = false;
string szLocalIPAddress = GetLocalIPAddress_AsString(); // Get local IP address as a default value
txtIPAddress.Text = szLocalIPAddress; // Place local IP address in IP address field
txtPort.Text = "8000"; // Default port number
}
private void btnConnect_Click(object sender, EventArgs e)
{
// Connect the Socket with a remote endpoint
try
{
// Create the socket, for TCP use
m_ClientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
m_ClientSocket.Blocking = true; // Socket operates in Blocking mode initially
}
catch // Handle any exceptions
{
Close_Socket_and_Exit();
}
try
{
// Get the IP address from the appropriate text box
String szIPAddress = txtIPAddress.Text;
System.Net.IPAddress DestinationIPAddress = System.Net.IPAddress.Parse(szIPAddress);
// Get the Port number from the appropriate text box
String szPort = txtPort.Text;
int iPort = System.Convert.ToInt16(szPort, 10);
// Combine Address and Port to create an Endpoint
m_remoteEndPoint = new System.Net.IPEndPoint(DestinationIPAddress, iPort);
m_ClientSocket.Connect(m_remoteEndPoint);
m_ClientSocket.Blocking = false; // Socket is now switched to Non-Blocking mode for send/ receive activities
txtLog.Text = "Connected";
m_CommunicationActivity_Timer.Start(); // Start the timer to perform periodic checking for received messages
}
catch // Catch all exceptions
{ // If an exception occurs, display an error message
txtLog.Text = "(Connect attempt failed)\nRetry Connect";
}
}
private void OnTimedEvent_PeriodicCommunicationActivityCheck(Object myObject, EventArgs myEventArgs)
{ // Periodic check whether a message has been received
try
{
EndPoint RemoteEndPoint = (EndPoint)m_remoteEndPoint;
byte[] ReceiveBuffer = new byte[1024];
int iReceiveByteCount;
iReceiveByteCount = m_ClientSocket.ReceiveFrom(ReceiveBuffer, ref RemoteEndPoint);
string szReceivedMessage;
if (0 < iReceiveByteCount)
{ // Copy the number of bytes received, from the message buffer to the text control
szReceivedMessage = Encoding.ASCII.GetString(ReceiveBuffer, 0, iReceiveByteCount);
txtResult.Text = szReceivedMessage;
}
}
catch // Silently handle any exceptions
{
}
}
private void Close_Socket_and_Exit()
{
try
{
m_ClientSocket.Shutdown(SocketShutdown.Both);
}
catch // Silently handle any exceptions
{
}
try
{
m_ClientSocket.Close();
}
catch // Silently handle any exceptions
{
}
this.Close();
}
private void btnDisconnect_Click(object sender, EventArgs e)
{
try
{
String szData = "QuitConnection"; // Special code to signal 'close connection' to the server
// This ensures that the server is aware the Client wants to close the connection
// (TCP should otherwise automatically detect disconnection, but this approach ensures a clean disconnect)
byte[] byData = System.Text.Encoding.ASCII.GetBytes(szData);
m_ClientSocket.Send(byData, SocketFlags.None);
m_ClientSocket.Shutdown(SocketShutdown.Both);
m_ClientSocket.Close();
btnConnect.Text = "Connect";
txtResult.Text = "";
}
catch // Silently handle any exceptions
{
}
}
private string GetLocalIPAddress_AsString()
{
string szHost = Dns.GetHostName();
string szLocalIPaddress = "127.0.0.1"; // Default is local loopback address
IPHostEntry IPHost = Dns.GetHostEntry(Dns.GetHostName());
foreach (IPAddress IP in IPHost.AddressList)
{
if (IP.AddressFamily == AddressFamily.InterNetwork) // Match only the IPv4 address
{
szLocalIPaddress = IP.ToString();
break;
}
} return szLocalIPaddress;
}
}
}
this is my first post, sorry in advance if I do something I shouldn't. I always search here for answer but this time I saw nothing about my problem. I have a project in C# where I keep alive a connection UDP listening a multicast IP from a data streaming.
The IP I'm listening is a multicast streamer that sends tracking data from many tracking systems, so we can assume the sender is not the problem. It sends like 1024 bytes packets, 60 fps.
This is a small example extracted from the whole project, simplified and as far as I tested, behaves in the same way as in the big project. The problem is that if I connect in localhost this never break, but if I connect to remote IPs this stop working, more or less, in 4 minutes.
public class TrackingStateObject
{
public Socket workSocket = null;
public const int BUFFER_SIZE = 65507;
public byte[] buffer = new byte[BUFFER_SIZE];
}
class MainClass
{
static public string multicastServerIPAddress = "239.255.42.99";
static public string realTrackingServerIPAddress = "161.116.27.144";
static protected EndPoint trackingEndPoint;
static public int dataPort = 2345;
static protected Socket sockData = null;
static int foo = 0;
public static void Main (string[] args)
{
IPEndPoint ipep;
TrackingStateObject so;
IPAddress trackingIP = IPAddress.Parse(multicastServerIPAddress);
trackingEndPoint = new IPEndPoint(trackingIP, dataPort);
sockData = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
ipep = new IPEndPoint(IPAddress.Any, dataPort);
try {
sockData.Bind(ipep);
}
catch (Exception ex) {
System.Console.WriteLine("[UDPClient] Exception "+ex.Message);
return;
}
sockData.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(trackingIP));
try {
trackingIP = IPAddress.Parse(realTrackingServerIPAddress);
trackingEndPoint = new IPEndPoint(trackingIP, dataPort);
}
catch(Exception ex) {
System.Console.WriteLine("[UDPClient] Exception "+ex.Message);
return;
}
so = new TrackingStateObject();
so.workSocket = sockData;
sockData.BeginReceiveFrom(so.buffer, 0, TrackingStateObject.BUFFER_SIZE, 0, ref trackingEndPoint, new AsyncCallback(AsyncReceiveCallback), so);
System.Threading.Thread.Sleep (600000);
}
private static void AsyncReceiveCallback(IAsyncResult ar)
{
try {
TrackingStateObject so = (TrackingStateObject)ar.AsyncState;
Socket sock = so.workSocket;
int read = sock.EndReceiveFrom(ar, ref trackingEndPoint);
if (read > 0)
{
// Do things with the data
System.Console.WriteLine("Recieved shit, " + read + " bytes, " + foo++ + " times.");
}
sock.BeginReceiveFrom(so.buffer, 0, TrackingStateObject.BUFFER_SIZE, SocketFlags.None, ref trackingEndPoint, new AsyncCallback(AsyncReceiveCallback), so);
}
catch (Exception e) {
System.Console.WriteLine("[UDPClient] Exception AsynCallback "+e.Message);
}
}
}
I debugged for a while and as far I can see is that always sock.BeginReceiveFrom is called, stop in some point, AsyncReceiveCallback is never executed again. Perhaps I'm doing here something stupid, but in any case, I'm not able to see it. Thanks!
I was having exactly the same problem, which only seems to occur on WiFi interfaces, not hardwired interfaces. The solution I discovered was to always set the SocketOptionName.AddMembership option before calling BeginReceiveFrom().
In the receive callback, after calling EndReceiveFrom() then set the SocketOptionName.DropMembership option for the multicast address.
Then before calling BeginReceiveFrom() again, set the SocketOptionName.AddMembership option.
Not sure why this has to be done for WiFi interfaces, but it worked for me.
I use the following piece of code to achieve this goal:
public static bool IsServerListening()
{
var endpoint = new IPEndPoint(IPAddress.Parse("201.212.1.167"), 2593);
var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
socket.Connect(endpoint, TimeSpan.FromSeconds(5));
return true;
}
catch (SocketException exception)
{
if (exception.SocketErrorCode == SocketError.TimedOut)
{
Logging.Log.Warn("Timeout while connecting to UO server game port.", exception);
}
else
{
Logging.Log.Error("Exception while connecting to UO server game port.", exception);
}
return false;
}
catch (Exception exception)
{
Logging.Log.Error("Exception while connecting to UO server game port.", exception);
return false;
}
finally
{
socket.Close();
}
}
Here is my extension method to the Socket class:
public static class SocketExtensions
{
public const int CONNECTION_TIMEOUT_ERROR = 10060;
/// <summary>
/// Connects the specified socket.
/// </summary>
/// <param name="socket">The socket.</param>
/// <param name="endpoint">The IP endpoint.</param>
/// <param name="timeout">The connection timeout interval.</param>
public static void Connect(this Socket socket, EndPoint endpoint, TimeSpan timeout)
{
var result = socket.BeginConnect(endpoint, null, null);
bool success = result.AsyncWaitHandle.WaitOne(timeout, true);
if (!success)
{
socket.Close();
throw new SocketException(CONNECTION_TIMEOUT_ERROR); // Connection timed out.
}
}
}
The problem is this piece of code works on my development environment but when I move it into production environment it always times out (regardless of whether I set the timeout interval to 5 or 20 seconds)
Is there some other way I could check if that IP is actively listening at that particular port?
What is the reason why I can't do this from my hosting environment?
You can run netstat -na from command line to see all (including listening) ports.
If you add -b you will also see linked executable to each connection/listening.
In .NET you can get all listening connections with System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties().GetActiveTcpListeners()
You can check it by using this code:
TcpClient tc = new TcpClient();
try
{
tc.Connect(<server ipaddress>, <port number>);
bool stat = tc.Connected;
if (stat)
MessageBox.Show("Connectivity to server available.");
tc.Close();
}
catch(Exception ex)
{
MessageBox.Show("Not able to connect : " + ex.Message);
tc.Close();
}
How can I check if a UNC Path is available?
I have the problem that the check takes about half a minute if the share is not available :
var fi = new DirectoryInfo(#"\\hostname\samba-sharename\directory");
if (fi.Exists)
//...
Is there a faster way to check if a folder is available?
I'm using Windows XP and C#.
How's this for a quick and dirty way to check - run the windows net use command and parse the output for the line with the network path of interest (e.g. \\vault2) and OK. Here's an example of the output:
C:\>net use
New connections will be remembered.
Status Local Remote Network
-------------------------------------------------------------------------------
OK O: \\smarty\Data Microsoft Windows Network
Disconnected P: \\dummy\Data Microsoft Windows Network
OK \\vault2\vault2 Microsoft Windows Network
The command completed successfully.
It's not a very .netish solution, but it's very fast, and sometimes that matters more :-).
And here's the code to do it (and LINQPad tells me that it only takes 150ms, so that's nice)
void Main()
{
bool available = QuickBestGuessAboutAccessibilityOfNetworkPath(#"\\vault2\vault2\dir1\dir2");
Console.WriteLine(available);
}
public static bool QuickBestGuessAboutAccessibilityOfNetworkPath(string path)
{
if (string.IsNullOrEmpty(path)) return false;
string pathRoot = Path.GetPathRoot(path);
if (string.IsNullOrEmpty(pathRoot)) return false;
ProcessStartInfo pinfo = new ProcessStartInfo("net", "use");
pinfo.CreateNoWindow = true;
pinfo.RedirectStandardOutput = true;
pinfo.UseShellExecute = false;
string output;
using (Process p = Process.Start(pinfo)) {
output = p.StandardOutput.ReadToEnd();
}
foreach (string line in output.Split('\n'))
{
if (line.Contains(pathRoot) && line.Contains("OK"))
{
return true; // shareIsProbablyConnected
}
}
return false;
}
Or you could probably go the route of using WMI, as alluded to in this answer to How to ensure network drives are connected for an application?
In my project I use the System.IO :
if (Directory.Exists(#"\\hostname\samba-sharename\directory")) { ...
and it's pretty fast so far...
In a project of mine, i had to check whether a server connection was established or not. I used a TCP Socket to asynchronically check whether the server could be reached or not. I wonder if you could use this to check on a network share. The async TCP Socket connect goes so fast i tested for the connection 10 times under 60 miliseconds. Maybe you could play around with that a bit ?
EDIT: Here is the Asynchronous Socket i used for my project. Use this class to check for a certain IP or address. Hope it is of any use to you
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.Threading;
namespace Base.BaseObjects
{
public class AsynchronousClient
{
#region Properties
private int _port = 0000, currentTry = 0, _buffersize, _fastpingdelay = 80;
private string _server = "localhost";
private Socket client;
private static IPEndPoint remoteEP;
// Delegates & Events
public delegate void SendMessageDelegate(string message);
public event SendMessageDelegate SendMessageEvent;
public delegate void ConnectionStatusDelegate(bool connected, bool reconnect);
public event ConnectionStatusDelegate ConnectionStatusChanged;
// ManualResetEvent instances signal completion.
private static ManualResetEvent connectDone = new ManualResetEvent(false);
private static ManualResetEvent sendDone = new ManualResetEvent(false);
private static ManualResetEvent receiveDone = new ManualResetEvent(false);
/// <summary>
/// Port to monitor
/// </summary>
public int Port { get { return _port; } }
/// <summary>
/// Number of packages to buffer until system reports connection loss
/// </summary>
public int BufferSize { get { return _buffersize; } }
/// <summary>
/// Time in milliseconds between two pings
/// </summary>
public int FastPingDelay { get { return _fastpingdelay; } }
/// <summary>
/// Servername to connect to
/// </summary>
public string Server
{
get { return _server; }
set
{
_server = value;
// Resolve the remote endpoint for the socket.
try
{
IPAddress ipAddress = (IPAddress)Dns.GetHostAddresses(value)[0];
remoteEP = new IPEndPoint(ipAddress, Port);
}
catch (SocketException ex)
{
SendMessage(ex.Message);
}
}
}
#endregion
#region Events & Delegates
protected void SendMessage(string message)
{
if (SendMessageEvent != null)
SendMessageEvent(message);
}
protected void UpdateConnectionStatus(bool connected, bool reconnect)
{
if (ConnectionStatusChanged != null)
ConnectionStatusChanged(connected, reconnect);
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete the connection.
client.EndConnect(ar);
SendMessage(String.Format("Socket connected to {0}", client.RemoteEndPoint.ToString()));
//UpdateConnectionStatus(true, false);
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
SendMessage(e.ToString());
UpdateConnectionStatus(false, true);
}
}
#endregion
#region methods
public AsynchronousClient(int port, string server)
{
_port = port;
Server = server;
_buffersize = 10;
_fastpingdelay = 20;
}
public void CreateSocket()
{
try
{
StopClient();
}
catch (Exception ex)
{
SendMessage(ex.Message);
}
finally
{
client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
}
}
public bool FastPingSocket()
{
for (currentTry = 0; currentTry <= BufferSize; currentTry++)
{
try
{
CreateSocket();
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
System.Threading.Thread.Sleep(FastPingDelay);
client.Shutdown(SocketShutdown.Receive);
connectDone.WaitOne();
client.Close();
return true;
}
catch (SocketException ex)
{
SendMessage(ex.Message);
}
catch (ObjectDisposedException ex)
{
currentTry--;
SendMessage(ex.Message);
CreateSocket();
}
catch (NullReferenceException ex)
{
currentTry--;
SendMessage(ex.Message);
CreateSocket();
}
catch (ArgumentNullException ex)
{
SendMessage(ex.Message);
CreateSocket();
}
catch (InvalidOperationException ex)
{
SendMessage(ex.Message);
CreateSocket();
currentTry--;
}
finally
{
StopClient();
}
}
UpdateConnectionStatus(false, true);
return false;
}
public void StopClient()
{
// Release the socket.
try
{
client.Shutdown(SocketShutdown.Both);
client.Close();
}
catch (Exception) { }
finally
{
UpdateConnectionStatus(false, false);
}
}
#endregion
}
}
Edit: Please don't just copy/paste it. Try to understand the code so you can use it for your benefit, and finetune it for your needs.
I ended up "cheating" and just pinging the host, which is reasonable as that in reality is the case that I'm checking for.
private bool HostExists(string PCName)
{
Ping pinger = new Ping();
try
{
PingReply reply = pinger.Send(PCName);
return reply.Status == IPStatus.Success;
}
catch
{
return false;
}
finally
{
pinger.Dispose();
}
}
This way suits me best because of its speed, simplicity, and reliability.
I used the ping method suggested above and it did not work for me since I am using OpenDNS
Here is a function that worked well for me:
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
/// <summary>
/// A quick method to test is the path exists
/// </summary>
/// <param name="s"></param>
/// <param name="timeOutMs"></param>
/// <returns></returns>
public static bool CheckPathExists(string s, int timeOutMs = 120) {
if (s.StartsWith(#"\\")) {
Uri uri = new Uri(s);
if (uri.Segments.Length == 0 || string.IsNullOrWhiteSpace(uri.Host))
return false;
if (uri.Host != Dns.GetHostName()) {
WebRequest request;
WebResponse response;
request = WebRequest.Create(uri);
request.Method = "HEAD";
request.Timeout = timeOutMs;
try {
response = request.GetResponse();
} catch (Exception ex) {
return false;
}
return response.ContentLength > 0;
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Do a Ping to see if the server is there
// This method doesn't work well using OPenDNS since it always succeeds
// regardless if the IP is a valid or not
// OpenDns always maps every host to an IP. If the host is not valid the
// OpenDNS will map it to 67.215.65.132
/* Example:
C:\>ping xxx
Pinging xxx.RT-AC66R [67.215.65.132] with 32 bytes of data:
Reply from 67.215.65.132: bytes=32 time=24ms TTL=55
*/
//Ping pingSender = new Ping();
//PingOptions options = new PingOptions();
// Use the default Ttl value which is 128,
// but change the fragmentation behavior.
//options.DontFragment = true;
// Create a buffer of 32 bytes of data to be transmitted.
//string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
//byte[] buffer = Encoding.ASCII.GetBytes(data);
//int timeout = 120;
//PingReply reply = pingSender.Send(uri.Host, timeout, buffer, options);
//if (reply == null || reply.Status != IPStatus.Success)
// return false;
}
}
return File.Exists(s);
}
Thats probably the quickest way, the delay will be the general network speed/disk access etc.
If this is causing a delay for the user, you could try checking this asynchronously?
Maybe you should try to create the folder, if it does exist, it will return an error that you could catch. There should be no default timeout.