I know this might have been asked a thousand times before, but I can't seem to find any specific information about my case.
I have a C# client program that has to connect to other instances of the client over a LAN. To connect one client to another, I use a TcpListener/TcpClient aproach. Both instances have a listener and are able to create a new client to connect/listen to one another (it is independant of which instance started the connection).
To create the listener, I use the following bit of code:
// In the constructor:
listener = new TcpListener(IPAddress.Any, 32842);
listenThread = new Thread((ThreadStart)ListenForConnections);
listenThread.Name = "ListenThread";
listenThread.IsBackground = true;
listenThread.Start();
// Listening for connections:
private void ListenForConnections()
{
listener.Start();
Console.WriteLine("Started listening for connections");
for (; ; )
{
if (listener.Pending())
{
using (TcpClient client = listener.AcceptTcpClient())
{
// My own layer over the TcpClient.
AsyncTCPClient other = new AsyncTCPClient(client);
Console.WriteLine("Connection from " + client.Client.RemoteEndPoint);
other.Received += DataReceived;
other.Exception += ExceptionOccurred;
connections.Add("Player", other);
other.Start();
}
}
else
{
Thread.Sleep(5);
}
}
}
To create and connect to another client, I use the following bit of code:
public void Connect(IPEndPoint other)
{
if (socket == null)
{
socket = new TcpClient(AddressFamily.InterNetwork);
socket.Client.ReceiveBufferSize = 2 * 1024 * 1024;
}
// Should force-close the socket after 5 seconds if it can't be closed automatically.
socket.LingerState = new LingerOption(true, 5);
socket.BeginConnect(other.Address, other.Port, ConnectionCallback, other);
IsConnecting = true;
}
The ConnectionCallback given as a parameter to BeginConnect looks like this:
private void ConnectionCallback(IAsyncResult result)
{
IsConnecting = false;
IsConnected = socket.Connected;
if (IsConnected)
{
IPEndPoint connectedTo = (IPEndPoint)result.AsyncState;
stream = socket.GetStream();
if (Connected != null)
{
Connected(this, null);
}
}
else
{
if (Exception != null)
{
RaiseException(new Exception("Unable to connect to host"));
}
}
}
However, everytime I get to the callback, the TcpClient failed to connect to the other instance and the Exception event is thrown. Now what I've found while searching around the internet (Google) is that it might have something to do with a firewall on either sides of the connection. But I've tested it with all firewalls off, so this can't be that.
I don't see Socket.EndConnect() being called in the callback.
See this in MSDN:
http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.endconnect.aspx
Related
I have an issue with my application,
I have a TCPListener which listen let's say on port 14000
After the application is being closed I can see on the CMD that the listener is still listening.
At the second run of the application as expected I cant start the listener on the same port (14000) because it is already taken, I am changing the application port to 15000 on the second running, work wonderful and the listener is being CLOSED after the application is being shut down,
I assume that on the first run, the first listener on port 14000 stays open after the app is dead, on the second run the application closed/open the listener on port 15000 very well, why is this happen? I thought maybe it is about the port 14000 I've switched the orders of the opening ports (first opened 15000) and saw that the 15000 stays open and the 14000 (on the second run) closed and open correctly, Why at the first run the listener not being closed??
The code to my server:
class Server : IDisposable
{
private const int TIMER_PERIOD = 60 * 1000; // ms
private string servePort;
private string serverIP;
byte[] DataReceived = new byte[1024];
Action<string> MssageReceiveCallback;
private bool isListening = false;
static Timer serverTimer = null;
private TcpListener _Server;
private Dictionary<int, TcpClient> clientsList = new Dictionary<int, TcpClient>();
private bool serverListening = true;
private static int ClientInstance = 0;
public Server(string _serverIP, string _serverPORT, Action<string> messageReceiveCallback)
{
serverIP = _serverIP;
servePort = _serverPORT;
MssageReceiveCallback = messageReceiveCallback;
// InitilizeServer();
}
private void InitilizeServer()
{
_Server = new TcpListener(IPAddress.Parse(serverIP), int.Parse(servePort));
// if (serverTimer == null)
// serverTimer = new Timer(new TimerCallback(OnTimerCallback), null, TIMER_PERIOD, TIMER_PERIOD);
Task.Run(() =>
{
try
{
_Server.Start();
while (_Server != null)
{
TcpClient tcpClient;
try
{
tcpClient = _Server.AcceptTcpClient();
}
catch
{
continue;
}
Task.Run(() =>
{
ClientInstance++;
int currentinstance = ClientInstance;
clientsList.Add(currentinstance, tcpClient);
try
{
while (tcpClient.Connected && serverListening)
{
if (tcpClient.GetStream().DataAvailable)
{
int actualBufferlength = tcpClient.GetStream().Read(DataReceived, 0, DataReceived.Length);
byte[] data = new byte[actualBufferlength];
Buffer.BlockCopy(DataReceived, 0, data, 0, actualBufferlength);
string asciiMessage = Encoding.ASCII.GetString(data);
MssageReceiveCallback(asciiMessage);
}
else
{
Thread.Sleep(5);
}
}
}
catch (Exception ex)
{
}
finally
{
clientsList[currentinstance].Close();
clientsList.Remove(currentinstance);
}
});
}
}
catch (Exception ex)
{
}
});
}
public void StartServer()
{
InitilizeServer();
isListening = true;
}
public void SendMessage(string msg)
{
byte[] data = ASCIIEncoding.ASCII.GetBytes(msg);
foreach (TcpClient client in clientsList.Values)
{
client.GetStream().Write(data, 0, data.Length);
}
}
public void Dispose()
{
serverListening = false;
foreach (var item in clientsList.Values)
{
if (item.Connected)
item.Close();
}
_Server.Server.Close();
}
}
UPDATE:
I've check in TCPView to see which application the listener bind to and found this:
It looks like the listener available for un exist process
The biggest problem here, I think (I've pointed out other problems in the comments) is that TCP shutdown requires network communications and by default prevents socket reuse for a period of time.
The function you need to get to is Socket.SetSocketOption, specifically the ReuseAddress option. You should be able to get at it via the Server property on the TcpListener. Pay attention that it needs to be done before you actually start the listener listening.
You could try putting:
_Server.Server =null;
After close.
I'm trying to program a custom UDP port sniffer. I'm trying to scan the local network looking for the UDP ports that are receiving data.Maybe this is a really trivial question, but I'm stuck here. I have tried a lot of examples and tutorials but I can't find a good solution. I have done this succesfully, using these two methods:
private static int udpListenPort = 1026;
bool flag=false;
public void ReceiveMessages()
{
for (udpListenPort = 1026; udpListenPort< 1200; udpListenPort++)
{
if (flag)
{
messageReceived = false;
IPEndPoint e = new IPEndPoint(IPAddress.Any, udpListenPort);
UdpClient u = new UdpClient(e);
UdpState s = new UdpState();
s.e = e;
s.u = u;
u.BeginReceive(new AsyncCallback(CheckUdpPort), s);
for (int i = 0; i < 5; i++)
{
Thread.Sleep(8);
if (messageReceived)
{
break;
}
}
if (messageReceived)
{
// Updating UI
}
//u.Close(); // I'm trying this but returns an exception
e = null;
u = null;
s = null;
}
}
}
And this:
public class UdpState
{
public IPEndPoint e;
public UdpClient u;
}
private static void CheckUdpPort(IAsyncResult ar)
{
UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u;
IPEndPoint e = (IPEndPoint)((UdpState)(ar.AsyncState)).e;
Byte[] data = u.EndReceive(ar, ref e);
// Some code to filter the data received
messageReceived = true;
}
I'm using these methods in a WPF program. When the scan finalize and I try to start it again, the IDE retunrs the following exception in this point:
IPEndPoint e = new IPEndPoint(IPAddress.Any, udpListenPort);
UdpClient u = new UdpClient(e); //HERE
UdpState s = new UdpState();
System.Net.Sockets.SocketException "Only one usage of each socket address (protocol/network address/port) is normally permitted."
I have tried to close each port, but the program returns the following exception "System.ObjectDisposedException" in this line:
Byte[] data = u.EndReceive(ar, ref e);
Any help will be very much appretiated.
Note: After more attempts, I realized that I only have the exception "Only one usage of each socket address (protocol/network address/port) is normally permitted. on the UDP ports that haven't received any data in the previous scan.
SOLVED. After more research and rough work, here is the working result. I have used synchronous reading, using the timeout to discard the UDP ports that are not receiving data.
private void BETAScanNetwork()
{
int contador = 0;
for (int i = 1140; i <= 1160; i++)
{
UdpClient listener = null;
bool incoming = false;
try
{
listener = new UdpClient(i);
var groupEp = new IPEndPoint(IPAddress.Any, i);
listener.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 50);
byte[] data = listener.Receive(ref groupEp);
incoming = true;
listener.Client.Shutdown(SocketShutdown.Both);
listener.Client.Close();
// Managing received data
}
catch (System.Net.Sockets.SocketException e)
{
var excp = e.SocketErrorCode;
if (excp== SocketError.TimedOut)
{
continue;
}
else
{
throw;
}
}
finally
{
if (listener != null && !incoming)
{
listener.Client.Shutdown(SocketShutdown.Receive);
listener.Close();
}
}
}
}
Thanks for the interest shown, #lord_alek1.
Have you tried:
u.Client.Shutdown();
u.Client.Close();
instead of the:
u.Close();
Following the msdn:
http://msdn.microsoft.com/en-us/library/wahsac9k.aspx
"For connection-oriented protocols, it is recommended that you call Shutdown before calling the Close method. This ensures that all data is sent and received on the connected socket before it is closed."
As you're working directly on the sockets, kinda.
UdpClient even implements IDisposable
public class UdpClient : IDisposable
Meaning you may use it in a
using(u = new UdpClient(foo)){
//do some stuff
}
Then you let the guys who made the client dispose of the sockets
if not;
do a
try{
//do stuff
}
finally{
u.client.shudown();
u.client.close();
}
the reason you had the original problem is because you should have re-used your object instead of creating a new one all the time. otherwise you will get the message "Only one usage of each socket address"
UdpClient u = new UdpClient(e);
unless your main thread has something more important to do during those 8milliseconds that you threading.thread.sleep(8), I would not even bother with async.. just use .receive() to wait/read from the socket buffer. and set the timeout as you did above in the end. btw thread.sleep can be anywhere from 8ms to 16ms minimum.
This is a follow on from this question
After some more Googling last night I managed to find a nice TCP tutorial I could follow that would allow me to look for connections on an Ip address and port number and display the data that is being sent.
However, I have an issue where my client connects once, I send a message and display it in the debug log but when I stop the application and run it again, Unity freezes. I'm at a loss as to why this happening. Could someone please take a look over this code to see where it might be happening and what I can do to fix it?
I also seem to boot out the connection as soon as I receive a message as well, why is that? The server can re-connect, but I want it to keep the connection once it has it.
public class TCP : MonoBehaviour
{
string ip_address = "127.0.0.1";
int port = 22;
Thread listen_thread;
TcpListener tcp_listener;
Thread clientThread;
TcpClient tcp_client;
bool isTrue = true;
// Use this for initialization
void Start ()
{
IPAddress ip_addy = IPAddress.Parse(ip_address);
tcp_listener = new TcpListener(ip_addy, port);
listen_thread = new Thread(new ThreadStart(ListenForClients));
listen_thread.Start();
Debug.Log("start thread");
}
private void ListenForClients()
{
this.tcp_listener.Start();
while(isTrue == true)
{
//blocks until a client has connected to the server
TcpClient client = this.tcp_listener.AcceptTcpClient();
//create a thread to handle communication
//with connected client
clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
clientThread.Start(client);
Debug.Log("Got client " + client);
}
}
private void HandleClientComm(object client)
{
tcp_client = (TcpClient)client;
NetworkStream client_stream = tcp_client.GetStream();
byte[] message = new byte[4096];
int bytes_read;
while(isTrue == true)
{
bytes_read = 0;
try
{
//blocks until a client sends a message
bytes_read = client_stream.Read(message, 0, 4096);
//Debug.Log(message);
}
catch (Exception e)
{
//a socket error has occured
Debug.Log(e.Message);
break;
}
if(bytes_read == 0)
{
//client has disconnected
Debug.Log("Disconnected");
tcp_client.Close();
break;
}
ASCIIEncoding encoder = new ASCIIEncoding();
Debug.Log(encoder.GetString(message,0,bytes_read));
}
if(isTrue == false)
{
tcp_client.Close();
Debug.Log("closing tcp client");
}
}
void OnApplicationQuit()
{
try
{
tcp_client.Close();
isTrue = false;
}
catch(Exception e)
{
Debug.Log(e.Message);
}
}
}
Here is a screen shot of my debug log as well to show whats happening:
update
updated code that has fixed the kicking of clients. The freeze issue is still persistent when I stop the unity application and re-start it.
further update
So after a little further experimenting I have worked out that my project isn't actually freezing. When I start the server (Unity) app the first time everything works fine. But when I close it and try to re run the server, it freezes, until I connect to it with a client. At which point the server works as normal.
So I think I'm not closing the open socket when I close down the server. How can I do that?
You must close the TCP socket that is listening. If you start the application for the first time, the TCP socket will be open. When you stop the application, the TCP socket is still opened and runs in the background.
void OnApplicationQuit()
{
try
{
tcp_client.Close();
isTrue = false;
}
catch(Exception e)
{
Debug.Log(e.Message);
}
// You must close the tcp listener
try
{
tcp_listener.Stop();
isTrue = false;
}
catch(Exception e)
{
Debug.Log(e.Message);
}
}
I am making a chat service for a game,
I am using a TCP listener an client for the account information, some sort of login service. I'm wondering if i can keep the socked the client connected to the server with, to check if he is still online, and keep sending him messages if he has new messages.
I already tried making a list of sockets for the login queue, but it disconnected the previous socket to to server as soon as i accepted a new socket.
byte[] usernameByte = new byte[100];
int usernameRecieved = s.Receive(usernameByte);
//guiController.setText(System.DateTime.Now + " Recieved Login...");
byte[] passByte = new byte[100];
int passRecieved = s.Receive(passByte);
//guiController.setText(System.DateTime.Now + " Recieved Password...");
string username = "";
string password = "";
for (int i = 0; i < usernameRecieved; i++)
username += (Convert.ToChar(usernameByte[i]));
for (int i = 0; i < passRecieved; i++)
password += (Convert.ToChar(passByte[i]));
if (DomainController.getInstance().checkAccount(username, password))
{
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("true"));
s.Send(asen.GetBytes("U are succesfully logged in, press enter to continue"));
guiController.setText(serverName,System.DateTime.Now+"");
guiController.setText(serverName, "Sent Acknowledgement - Logged in");
}
else
{
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("false"));
s.Send(asen.GetBytes("U are NOT logged in, press enter to continue"));
guiController.setText(serverName, System.DateTime.Now + "");
guiController.setText(serverName, "\nSent Acknowledgement - Not logged in");
}
This is the code i currently use to check the account information the user send me. Right after i send this the user dropd the connection and i move on to the next one.
I have tried making 1 list of seperate sockets and processing them one by one, but that failed because the previous socket's connection dropped, even tho it were 2 different machines that tried to connect.
Does anyone have a sollution / a way to save sockets, that I can use to make the program keep all the connections alive? so i can send a message from user 1 to user 2, and just use the socket they connected with? or do i need to add an id every time they make a connection?
EDIT
The client Code: (this is just a test client)
while (true)
{
TcpClient tcpclnt = new TcpClient();
Console.WriteLine("Connecting.....");
tcpclnt.Connect("xx.xxx.xxx.xx", 26862);
// use the ipaddress as in the server program
while(!(checkResponse(tcpclnt.GetStream())))
{
Thread.Sleep(1000);
}
Console.WriteLine("Connected");
Console.Write("Enter the string to be transmitted : ");
String str = Console.ReadLine();
if (str == "")
{
str = " ";
}
Stream stm = tcpclnt.GetStream();
ASCIIEncoding asen = new ASCIIEncoding();
byte[] ba = asen.GetBytes(str);
Console.WriteLine("Transmitting.....");
stm.Write(ba, 0, ba.Length);
Console.Write("Enter the string to be transmitted : ");
String str2 = Console.ReadLine();
if (str2 == "")
{
str2 = " ";
}
Stream stm2 = tcpclnt.GetStream();
ASCIIEncoding asen2 = new ASCIIEncoding();
byte[] ba2 = asen2.GetBytes(str2);
Console.WriteLine("Transmitting.....");
stm.Write(ba2, 0, ba2.Length);
if (str == "false")
{
blijvenWerken = false;
}
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]));
byte[] bb2 = new byte[100];
int k2 = stm.Read(bb2, 0, 100);
Console.Write("\n");
for (int i = 0; i < k2; i++)
Console.Write(Convert.ToChar(bb2[i]));
Console.WriteLine("\n");
tcpclnt.Close();
Thread.Sleep(1000);
}
Server getting the sockets:
This bit of code is on the loginserver, its because i can only accept 1 socket every time to keep the connection alive, that i put queueCount on a maximum of 1.
I want to be able to make a list of Sockets that i accepted to add to a User account.
while (loginServerOn)
{
if (queueCount < 1)
{
if (loginServer.getLoginListener().Pending())
{
loginQueue.Add(loginServer.getSocket());
ASCIIEncoding asen = new ASCIIEncoding();
Socket s = loginQueue.First();
try
{
s.Send(asen.GetBytes("true"));
queueCount++;
}
catch
{
loginQueue.Remove(s);
}
}
}
}
The function that returns the accepted socket.
public Socket getSocket()
{
return myList.AcceptSocket();
}
EDIT: Essence of the question
I want to add the socked or client recieved to my Account object, so every connection has an Account its linked to, when i want to send a message to a certain account, it should send a message to the socked or client bound to that account, can you help/show me how i can achieve this?
This is still c# and sockets but my approach is different to yours.
I went with the concept of a "connectedCleint" which is similar in purpose to what you've called an account.
I have a class called ServerTerminal which is responsible for accepting and top level management of socket connections. In this i've got:
public Dictionary<long, ConnectedClient> DictConnectedClients =
new Dictionary<long, ConnectedClient>();
So this is my list of connected clients indexed by the sockethandle.
To accept connections i've got a routine:
public void StartListen(int port)
{
socketClosed = false;
IPEndPoint ipLocal = new IPEndPoint(IPAddress.Any, port);
listenSocket = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
//bind to local IP Address...
//if ip address is allready being used write to log
try
{
listenSocket.Bind(ipLocal);
}
catch (Exception excpt)
{
// Deal with this.. write your own log code here ?
socketClosed = true;
return;
}
//start listening...
listenSocket.Listen(100); // Max 100 connections for my app
// create the call back for any client connections...
listenSocket.BeginAccept(new AsyncCallback(OnClientConnection), null);
}
So when a client connects it then fires off:
private void OnClientConnection(IAsyncResult asyn)
{
if (socketClosed)
{
return;
}
try
{
Socket clientSocket = listenSocket.EndAccept(asyn);
ConnectedClient connectedClient = new ConnectedClient(clientSocket, this, _ServerTerminalReceiveMode);
//connectedClient.MessageReceived += OnMessageReceived;
connectedClient.Disconnected += OnDisconnection;
connectedClient.dbMessageReceived += OndbMessageReceived;
connectedClient.ccSocketFaulted += ccSocketFaulted;
connectedClient.StartListening();
long key = clientSocket.Handle.ToInt64();
if (DictConnectedClients.ContainsKey(connectedClient.SocketHandleInt64))
{
// Already here - use your own error reporting..
}
lock (DictConnectedClients)
{
DictConnectedClients[key] = connectedClient;
}
// create the call back for any client connections...
listenSocket.BeginAccept(new AsyncCallback(OnClientConnection), null);
}
catch (ObjectDisposedException excpt)
{
// Your own code here..
}
catch (Exception excpt)
{
// Your own code here...
}
}
The crucial part of this for you is:
// create the call back for any client connections...
listenSocket.BeginAccept(new AsyncCallback(OnClientConnection), null);
This sets up the serverterminal to receive new connections.
Edit:
Cut down version of my connectedclient:
public class ConnectedClient
{
private Socket mySocket;
private SocketIO mySocketIO;
private long _mySocketHandleInt64 = 0;
// These events are pass through; ConnectedClient offers them but really
// they are from SocketIO
public event TCPTerminal_ConnectDel Connected
{
add
{
mySocketIO.Connected += value;
}
remove
{
mySocketIO.Connected -= value;
}
}
public event TCPTerminal_DisconnectDel Disconnected
{
add
{
mySocketIO.Disconnected += value;
}
remove
{
mySocketIO.Disconnected -= value;
}
}
// Own Events
public event TCPTerminal_TxMessagePublished TxMessageReceived;
public delegate void SocketFaulted(ConnectedClient cc);
public event SocketFaulted ccSocketFaulted;
private void OnTxMessageReceived(Socket socket, TxMessage myTxMessage)
{
// process your message
}
private void OnMessageSent(int MessageNumber, int MessageType)
{
// successful send, do what you want..
}
public ConnectedClient(Socket clientSocket, ServerTerminal ParentST)
{
Init(clientSocket, ParentST, ReceiveMode.Handler);
}
public ConnectedClient(Socket clientSocket, ServerTerminal ParentST, ReceiveMode RecMode)
{
Init(clientSocket, ParentST, RecMode);
}
private void Init(Socket clientSocket, ServerTerminal ParentST, ReceiveMode RecMode)
{
ParentServerTerminal = ParentST;
_myReceiveMode = RecMode;
_FirstConnected = DateTime.Now;
mySocket = clientSocket;
_mySocketHandleInt64 = mySocket.Handle.ToInt64();
mySocketIO = new SocketIO(clientSocket, RecMode);
// Register for events
mySocketIO.TxMessageReceived += OnTxMessageReceived;
mySocketIO.MessageSent += OnMessageSent;
mySocketIO.dbMessageReceived += OndbMessageReceived;
}
public void StartListening()
{
mySocketIO.StartReceiving();
}
public void Close()
{
if (mySocketIO != null)
{
mySocketIO.Close();
mySocketIO = null;
}
try
{
mySocket.Close();
}
catch
{
// We're closing.. don't worry about it
}
}
public void SendMessage(int MessageNumber, int MessageType, string Message)
{
if (mySocket != null && mySocketIO != null)
{
try
{
mySocketIO.SendMessage(MessageNumber, MessageType, Message);
}
catch
{
// mySocketIO disposed inbetween check and call
}
}
else
{
// Raise socket faulted event
if (ccSocketFaulted != null)
ccSocketFaulted(this);
}
}
}
}
Some useful links:
This is where I started:
http://vadmyst.blogspot.com.au/2008/01/how-to-transfer-fixed-sized-data-with.html
http://vadmyst.blogspot.com.au/2008/03/part-2-how-to-transfer-fixed-sized-data.html
And..
C# Sockets and Multithreading
Cause a connected socket to accept new messages right after .BeginReceive?
http://nitoprograms.blogspot.com.au/2009/04/tcpip-net-sockets-faq.html
http://www.codeproject.com/Articles/83102/C-SocketAsyncEventArgs-High-Performance-Socket-Cod
I can't post my entire solution just now; there is a flaw in my server code I need to debug; plus there are parts which my employer may not want published. But i based my code on what Vadym had for variable length messages.
When a server gets ready to accept TCP connections, it creates a new TCP socket, Bind() it to a port and uses the Listen() method. When a connection request comes in, the Listen() method returns a new socket that the server and client use for communication. The server and client can pass data back and forth using Send() and Receive() at this point. If the client disconnects, the server's Receive() terminates with 0 bytes of data.
If you want to wait for another connection request once you've accepted the first connection (i.e., while you are interacting with the first client) this can be done. At this point, you'll need to use something like threads or asynchronous methods so you can handle more than one connection. Basically, you will be able to Accept() connection requests from your listening socket.
Mike
How do I get all servers IP which are listening on specific port (Ex:9090) in LAN
I have already read some basics information about multicast,anycast ,unicast and broadcast and it seems like broadcast is the one meant for my application.
I am thinking of two ideas .. Use TCP protocol to Connect to all IP Addresses (192.168.1.1-254) in parallel on port 9090 and set a little time period to the connection timeout. just to check if there's any responce. (but it doesn't seem like a good idea)Use UDP protocol and broadcast a message like "hello" and check for response then get all IP Addresses which respond.
So which idea should I pick, are there better ideas to do it?
I would also like to know if my broadcast-ed message is received to the server and how to get the IP address of it.
I've done it with TCP to search all server that is listening on a specific port.
Its not an idle solution, but it worked for me.
I've created a userControl with a public function Initialize to pass the port that i want to scan for servers.
public ServerDiscovery()
{
InitializeComponent();
// statusLabel.Image = imageState.Images[2];
timer.Elapsed += timer_tick;
}
int port = 0;
bool busy = false; // to tell that the function is busy with scanning.
public void Initialize(int port)
{
this.port = port;
}
System.Timers.Timer timer = new System.Timers.Timer(5000);
List<SocketAsyncEventArgs> list = new List<SocketAsyncEventArgs>();
// this list to hold all sockets that created to connect to IP .. to DISPOSE it later
HashSet<string> usedIP = new HashSet<string>();
//usedIP will be explained later.
public IPEndPoint getAddress()
{ //this function to get the IPEndPoint of the selected server from listview.
if (listServer.SelectedItems.Count > 0)
{
if (listServer.SelectedItems[0].ImageIndex == 0)
{
ListViewItem item = listServer.SelectedItems[0];
IPEndPoint ep = new IPEndPoint(IPAddress.Parse(item.SubItems[1].Text), port);
return ep;
}
}
return null;
}
public void Refresh() //to scan for servers
{
if (!busy)
{
usedIP.Clear();
listServer.Items.Clear();
// statusLabel.Text = "Scanning for servers.";
// statusLabel.Image = Image.FromFile("loading.gif");
// btnRefresh.Enabled = false;
busy = true;
timer.Start();
IPAddress[] IpA = Dns.GetHostByName(Dns.GetHostName()).AddressList;
for (int j = 0; j < IpA.Length ; j++)
{
if (IpA[j].AddressFamily == AddressFamily.InterNetwork) // to make sure it's an IPV4
{
string scanIP = IpA[j].ToString().Substring(0, IpA[j].ToString().LastIndexOf(".")) + ".";
if (!usedIP.Contains(scanIP))
//usedIP is a hashset that holds the first 3 parts on an ip (ex:"192.168.1." from "192.168.1.30") i used this to avoid scanning the same ip addresses more than once .. like if i had a wireless network ip ("192.168.1.5") and an Ethernet Network ip ("192.168.1.5"). so with that hashset it will scan once.
{
usedIP.Add(scanIP);
Parallel.For(1, 255, i =>
{
Scan(scanIP + i);
});
}
}
}
}
}
private void Scan(string ipAdd)
{
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
SocketAsyncEventArgs e = new SocketAsyncEventArgs();
e.RemoteEndPoint = new IPEndPoint(IPAddress.Parse(ipAdd), port);
e.UserToken = s;
e.Completed += new EventHandler<SocketAsyncEventArgs>(e_Completed);
list.Add(e); // add the created socket to a list to dispose when time is up.
s.ConnectAsync(e);
}
private void e_Completed(object sender, SocketAsyncEventArgs e)
{
if (e.ConnectSocket != null) //if there's a responce from the server [e.ConnectSocket] will not be equal null.
{
StreamReader sr = new StreamReader(new NetworkStream(e.ConnectSocket));
ListViewItem item = new ListViewItem();
string[] cmd = sr.ReadLine().Split('<'); in my server constructor this line will receive a string like "PC_NAME<Available" ..
item.Text = cmd[0];
item.SubItems.Add(((IPEndPoint)e.RemoteEndPoint).Address.ToString());
item.SubItems.Add(cmd[1]);
if (cmd[1] == "Busy")
item.ImageIndex = 1;
else
item.ImageIndex = 0;
AddServer(item);
list.Remove(e); //active server should be remove from the list that holds the sockets and disposed.. because there's no need to keep connection after showing that this server is active.
((Socket)e.UserToken).Dispose();
}
}
delegate void AddItem(ListViewItem item);
private void AddServer(ListViewItem item)
{
if (InvokeRequired)
{
Invoke(new AddItem(AddServer), item); //just to add an item from a background thread.
return;
}
listServer.Items.Add(item);
}
private void timer_tick(object sender, EventArgs e)
{
busy = false; //when time's up .. set busy to false so we can scan again
timer.Stop();
foreach (var s in list) //dispose all sockets that's trying to connect and waiting for a response
{
try
{
((Socket)s.UserToken).Dispose();
}
catch { }
}
//this.Invoke((MethodInvoker)delegate // for design
// {
// btnRefresh.Enabled = true;
// btnRefresh.BorderStyle = Border3DStyle.Raised;
// statusLabel.Text = "Ready.";
// statusLabel.Image = imageState.Images[2];
// });
}
private void btnRefresh_Click(object sender, EventArgs e)
{
// btnRefresh.BorderStyle = Border3DStyle.Sunken;
Refresh();
}
// private void listServer_KeyUp(object sender, KeyEventArgs e)
// {
// if (e.KeyCode == Keys.F5)
// {
// btnRefresh_Click(sender, (EventArgs)e);
// }
// }
}
Again this's not an ideal solution that works on any case but it worked fine with me.