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Send a flag from server to clients using c# mouse events

I am using sockets in c# in order to send data from server to client machine. In fact I have created a capturer which capature kinect stream from 3 different machine. I want to generate a server and client communication in order to send signal from server to the rest devices in order to begin and stop the recording process. I want with left click to send a message to begin recording and with right click to stop recording. My code is the following:
public Form1()
{
InitializeComponent();
this.MouseClick += mouseClick1;
Thread thread = new Thread(() => StartServer(message));
thread.Start(); // server is begining
}
private void mouseClick1(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
message = "start";
try
{
obj = new Capturer(dirPath + name + "_" + surname, 20);
}
catch (Exception e1)
{
Console.WriteLine("The process failed: {0}", e1.ToString());
}
if (clientSockets.Count > 0)
{
Thread.Sleep(10);
foreach (Socket socket1 in clientSockets)
socket1.Send(Encoding.ASCII.GetBytes(message)); //send everything to all clients as bytes
}
else
{
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), null); //to receive another client
}
}
else if (e.Button == MouseButtons.Right)
{
message = "stop";
obj.flag2 = true;
if (clientSockets.Count > 0)
{
Thread.Sleep(10);
foreach (Socket socket1 in clientSockets)
socket1.Send(Encoding.ASCII.GetBytes(message)); //send everything to all clients as bytes
}
else
{
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), null); //to receive another client
}
}
}
public void StartServer(String message) {
serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
serverSocket.Bind(new IPEndPoint(IPAddress.Any, PORT_NO));
serverSocket.Listen(4); //the maximum pending client, define as you wish
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), null);
string result = "";
do
{
result ="asdf";
} while (result.ToLower().Trim() != "exit");
}
private const int BUFFER_SIZE = 4096;
private static byte[] buffer = new byte[BUFFER_SIZE]; //buffer size is limited to BUFFER_SIZE per message
private static List<Socket> clientSockets = new List<Socket>(); //may be needed by you
private static void acceptCallback(IAsyncResult result)
{ //if the buffer is old, then there might already be something there...
Socket socket = null;
try
{
socket = serverSocket.EndAccept(result); // The objectDisposedException will come here... thus, it is to be expected!
//Do something as you see it needs on client acceptance
clientSockets.Add(socket);
socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(receiveCallback), socket);
string msg = "start";
//socket.Send(Encoding.ASCII.GetBytes(msg));
if (clientSockets.Count > 0)
{
Thread.Sleep(10);
foreach (Socket socket1 in clientSockets)
socket1.Send(Encoding.ASCII.GetBytes(msg)); //send everything to all clients as bytes
}
else
{
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), null); //to receive another client
}
}
catch (Exception e)
{ // this exception will happen when "this" is be disposed...
//Do something here
Console.WriteLine(e.ToString());
}
}
const int MAX_RECEIVE_ATTEMPT = 10;
static int receiveAttempt = 0; //this is not fool proof, obviously, since actually you must have multiple of this for multiple clients, but for the sake of simplicity I put this
private static void receiveCallback(IAsyncResult result)
{
Socket socket = null;
try
{
socket = (Socket)result.AsyncState; //this is to get the sender
if (socket.Connected)
{ //simple checking
int received = socket.EndReceive(result);
if (received > 0)
{
byte[] data = new byte[received]; //the data is in the byte[] format, not string!
Buffer.BlockCopy(buffer, 0, data, 0, data.Length); //There are several way to do this according to http://stackoverflow.com/questions/5099604/any-faster-way-of-copying-arrays-in-c in general, System.Buffer.memcpyimpl is the fastest
//DO SOMETHING ON THE DATA int byte[]!! Yihaa!!
Console.WriteLine(Encoding.UTF8.GetString(data)); //Here I just print it, but you need to do something else
//Message retrieval part
//Suppose you only want to declare that you receive data from a client to that client
string msg = "I receive your message on: " + DateTime.Now;
socket.Send(Encoding.ASCII.GetBytes(msg)); //Note that you actually send data in byte[]
Console.WriteLine("I sent this message to the client: " + msg);
receiveAttempt = 0; //reset receive attempt
//socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(receiveCallback), socket); //repeat beginReceive
}
else if (receiveAttempt < MAX_RECEIVE_ATTEMPT)
{ //fail but not exceeding max attempt, repeats
++receiveAttempt; //increase receive attempt;
socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(receiveCallback), socket); //repeat beginReceive
}
else
{ //completely fails!
Console.WriteLine("receiveCallback fails!"); //don't repeat beginReceive
receiveAttempt = 0; //reset this for the next connection
}
}
}
catch (Exception e)
{ // this exception will happen when "this" is be disposed...
Console.WriteLine("receiveCallback fails with exception! " + e.ToString());
}
}
How can I parse the flag into the server, in order to send that value in the clients? Is it possible to change here the static type of server functions? As it is now the code begin the server which send just the string "start" to the clients. How can I send the string message of a bool flag? My issue lies in the static type of my callback functions. Is it possible to add as an argument the message for example in the AsyncCallBack:
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), null);

Firstly, about the MouseClick event. Since you are having exclusive qualification for the event (that is, one left click and another right click), you could combine them both into a single event
public Form1()
{
InitializeComponent();
this.MouseClick += mouseClick1; //one event is enough
Thread thread = new Thread(() => StartServer(message));
thread.Start(); // server is begining
}
private void mouseClick1(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
try
{
obj = new Capturer(dirPath + name + "_" + surname, 20); //captures the kinect streams
}
catch (Exception e1)
{
Console.WriteLine("The process failed: {0}", e1.ToString());
}
}
else if (e.Button == MouseButtons.Right)
{
obj.flag2 = true; // flag that handle the recording, true value stops the recording, possible I want that value to be send to the client in order the same thing happen.
}
}
And it is going to be ok.
Next, answering your questions:
Q: How can I parse the flag into the server, in order to send that value
in the clients?
A: in your mouseClick1 event, simply use sync send which you do in your accept callback, change the msg with something else (say byte[] val = new byte[] { 1 };)
foreach (Socket socket1 in clientSockets) //Do this in your `if (e.Button == Mouse.Left and Mouse.Right) blocks
socket1.Send(Encoding.ASCII.GetBytes(msg));
Q: Is it possible to change here the static type of server functions?
A: Yes, definitely! it is windows form, you do not need to use static
type at all! Unlike the Console App in your previous question. I would
even suggest you to make nothing static whenever possible
Q: As it is now the code begin the server which send just the string
"start" to the clients. How can I send the string message of a bool
flag?
A: since you use socket, you cannot really send bool flag so to
speak. You will send byte[]. But you can always check in your
client implementation. If the byte[] is of certain value, simply
change it to bool. For instance, consider of sending just 1 or 0
from your server. Then in your client endReceiveCallback, you could
simply check the data coming and see if it is 1 then it is true,
and if it is 0 then it is false
Q: My issue lies in the static type of my callback functions. Is it
possible to add as an argument the message for example in the
AsyncCallBack
A: this is winform, you could get rid of all static var! And yes,
just pass it as replacement of the null in your Begin callback.
Then you pass the object too.
//Change null with something else
serverSocket.BeginAccept(new AsyncCallback(acceptCallback), myobj);
Then in your acceptCallback, take your object by using the IAsyncResult.AsyncState

Stream for sending byte-arrays and strings (for network)

I'm searching for a Streamclass which contains:
- a method for sending/receiving a byte-array
- a method for sending/receiving a string
The only Class I've found was NetworkStream. But the disadvantage with the NetworkStream-Class is, that if i want sending a string, i must befor convert this string into a byte-array and send this byte-array, because there is no method for sending strings directly.
And on the other side classes like Streamwriter have methods for sending/receiving strings, but there have no methods for sending/receiving a byte-array.
And if i try to combine these two Streamclasses like this:
TcpClient clientConnection = new TcpClient();
NetworkStream nws = clientConnection.GetStream();
StreamWriter sw = new StreamWriter(nws);
sw.writeLine("ABC");
sw.Flush();
nws.Write(byteArray, 0, lengthToSend);
i get a lot of strange errors (like byteArray will not receive on the other side completly), because i'm using here the same one stream in two different ways.
So, must i used NetworkStream-Class for my plan or exists there a better way?

I had the same problem,and the point is that the other side doesnt know what you are sending byte array or string so what i did is putting a header for each msg specially when dealing with serious server/client application coz you will have multiple data (user info, requesting info,replying info .. etc)
i am using streamwriter to send and streamreader to receive but i am also using threads
the connection remains open as long as the client is connected so i declare them once
here is a full example of my codes
public class Client
{
private StreamWriter swSender;
private StreamReader srReceiver;
private TcpClient tcpServer;
private Thread thrMessaging;
private string UserName = "UK";
private byte Tries = 0;
private bool Connected = false;
public void Connect()
{
if (!Connected)
{
IPAddress[] localIPs = Dns.GetHostAddresses(Dns.GetHostName());
string User = localIPs[0].ToString();
string ServIP = "127.0.0.1";//change this to your server ip
InitializeConnection(ServIP, User);
}
else
{
CloseConnection("Disconnected at user's request.");
}
}
private void InitializeConnection(string ServIp, string User)
{
IPAddress ipAddr = IPAddress.Parse(ServIp);
tcpServer = new TcpClient();
try
{
tcpServer.Connect(ipAddr, 1986);//change that 1986 to your server port
}
catch
{
if (Connected) CloseConnection("");
MessageBox.Show("Connecteing to " + ServIp + "\r\nServer is Down ... Try nomber " + Tries); return;
}
Connected = true;
UserName = User;
swSender = new StreamWriter(tcpServer.GetStream());
swSender.WriteLine(User);
swSender.Flush();
thrMessaging = new Thread(new ThreadStart(ReceiveMessages));
thrMessaging.Start();
}
private void ReceiveMessages()
{
srReceiver = new StreamReader(tcpServer.GetStream());
string ConResponse = srReceiver.ReadLine();
if (ConResponse[0] == '1')
{
}
else
{
string Reason = "Not Connected: ";
Reason += ConResponse.Substring(2, ConResponse.Length - 2);
return;
}
while (Connected)
{
try
{
string NewMsg = srReceiver.ReadLine();
if (NewMsg != null && NewMsg != "")
PacketHandler.HandlePacket(NewMsg, this);
}
catch { }
}
}
public void CloseConnection(string Reason)
{
try
{
Connected = false;
swSender.Close();
srReceiver.Close();
tcpServer.Close();
}
catch { }
}
public void SendMessage(string Msg)
{
if (Msg.Length >= 1)
{
try
{
Tries++;
swSender.WriteLine(Msg);
swSender.Flush();
Tries = 0;
}
catch
{
if (Tries < 5)
{
try
{
CloseConnection("No connection made");
Connect();
}
catch { }
SendMessage(Msg);
}
else { MessageBox.Show("Connecting to server faild for 5 tries"); Tries = 0; }
}
}
}
then at the packet handler i do my handling to check what kind of data the client received
something like this
public static void HandlePacket(string MsgRec, Client Client)
{
string[] Info = MsgRec.Split('|');
string Type = Info[0];
if (Type == "")
{
return;
}
string subtype = Info[1];
int TLen = Type.Length + subtype.Length + 2;
string Data = MsgRec.Remove(0, TLen);//this is the main data the server sent
ushort PacketType = ushort.Parse(Type);
ushort SubType = ushort.Parse(subtype);
switch ((Structs.PacketType)PacketType)
{
case Structs.PacketType.Login:
{
//do your stuff here
break
}
case Structs.PacketType.Image:
{
//convert the Data back to byte array then get the image out from it
break
}
case Structs.PacketType.ByteArray:
{
//convert the Data back to byte array
break
}
}
}
i know its kinda messy and not the perfect way to do it , but it works for me
and remember that at the other side when sending something you need to add the packet type and subtype , or just any header with any splitter if u doin something simple
Finally : i think using Sockets and packets would be much easier if u are sending small packets length

UDP Connection Between Client and Server

Here is the server code of my program this is working, but after it sends data it gets stuck. I need it to be refreshed and ready for sending data again.
Server code:
private void button1_Click(object sender, EventArgs e) {
try {
String text = textBox1.Text;
UdpClient udpc = new UdpClient(text,8899);
IPEndPoint ep = null;
while (true) {
MessageBox.Show("Name: ");
string name = textBox2.Text;
if (name == "") break;
byte[] sdata = Encoding.ASCII.GetBytes(name);
udpc.Send(sdata, sdata.Length);
if (udpc.Receive(ref ep)==null) {
MessageBox.Show("Host not found");
} else {
byte[] rdata = udpc.Receive(ref ep);
string job = Encoding.ASCII.GetString(rdata);
MessageBox.Show(job);
}
}
} catch {
MessageBox.Show("Error Restarting");
}
Client code:
private void button1_Click(object sender, EventArgs e) {
try {
UdpClient subscriber = new UdpClient(8899);
IPAddress addr = IPAddress.Parse("127.0.0.2");
subscriber.JoinMulticastGroup(addr);
IPEndPoint ep = null;
for (int i = 0; i < 1; i++) {
byte[] pdata = subscriber.Receive(ref ep);
string strdata = Encoding.ASCII.GetString(pdata);
MessageBox.Show(strdata);
textBox1.Text = strdata;
pass = strdata;
}
subscriber.DropMulticastGroup(addr);
} catch {
Refresh();
MessageBox.Show("Not Found");
}
}
The Server can send data to one client . I want to send one client at a time. But after sending the data, the server gets stuck.
I need it do refresh and send data again for a client.

If I understood your code, from the server your sending data, then waiting for an answer. In the client, your just getting the data, but not sending anything back. And unless you provide timeout to the socket, it will wait indefinitely until something arrives.

You shouldn't use udpc.Receive() in the main UI thread (inside button1_Click). If you do, your aplication will hang until something arrives. Using a timeout isn't a solution either. The application will just hang until the timeout expires. Instead You must use a multiple threads. You can do so by using BeginReceive instead of Receive or by explicitly creating a new thread and using Receive there. If you google for "asynchronous udp sockets in c#" or something like that, then you will find plenty of examples on how to set it up correctly.

The udpc.Receive() Method on your server side, will Block Until a datagram receive from client.
UDP in not reliable. it means that server doesnt expect any ACK from other side. so you can simply remove this part of code. or if you need to ensure message arrival, run a separate thread for each client as follow:
private void button1_Click(object sender, EventArgs e) {
System.Threading.Thread Server_thread = new Thread(My_Send_Function);
Server_thread .Start();
}
private void My_Send_Function() {
try {
String text = textBox1.Text;
UdpClient udpc = new UdpClient(text,8899);
IPEndPoint ep = null;
while (true) {
MessageBox.Show("Name: ");
string name = textBox2.Text;
if (name == "") break;
byte[] sdata = Encoding.ASCII.GetBytes(name);
udpc.Send(sdata, sdata.Length);
if (udpc.Receive(ref ep)==null) {
MessageBox.Show("Host not found");
} else {
byte[] rdata = udpc.Receive(ref ep);
string job = Encoding.ASCII.GetString(rdata);
MessageBox.Show(job);
}
}
} catch {
MessageBox.Show("Error Restarting");
}
}

C# UDP packetloss though all packets arrive (WireShark)

As the title says I have a problem with UDP in C#.
I'm trying to build a library for the rcon protocol of the game DayZ.
My problem is that I dont receive every packet I should receive.
After sending a command the server replies with an split answer. The packet header contains the total packet count and the index of the current packet.
Now if I should get 17 packets I only get 8-15 packets in my application.
After testing with WireShark I know now that all packages arrive on my computer. They just dont get recognized by my application or something like that.
My Actual Question is:
Is it possible to prevent losing the packages between my network card and my application? or
Why does that happen?
Here is my current code. Its pretty dirty because I ripped it apart after not working as expected:
private Socket _udpClient;
private Thread _receiverThread;
private Thread _workerThread;
private Queue<byte[]> _packetQueue;
private PacketBuffer[] MessageBuffer;
private byte SenderSequence = 0;
private IPEndPoint connection;
public RCon(IPAddress ip, int port)
{
connection = new IPEndPoint(ip, port);
_udpClient = new Socket(connection.Address.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
_udpClient.Connect(connection);
MessageBuffer = new PacketBuffer[256];
_packetQueue = new Queue<byte[]>();
_receiverThread = new Thread(new ThreadStart(ReceiveCallback));
_receiverThread.IsBackground = true;
_receiverThread.Priority = ThreadPriority.AboveNormal;
_receiverThread.Start();
_workerThread = new Thread(new ThreadStart(WorkerCallback));
_workerThread.IsBackground = true;
_workerThread.Start();
}
public void Login(string password)
{
LoginPacket packet = new LoginPacket(password);
_udpClient.Send(packet.Bytes);
}
public void SendCommand(string command)
{
CommandPacket packet = new CommandPacket(SenderSequence, command);
SenderSequence++;
_udpClient.Send(packet.Bytes);
}
private void ReceiveCallback()
{
while (true)
{
byte[] buffer = new byte[1036];
if (_udpClient.Receive(buffer) > 0)
_packetQueue.Enqueue(buffer);
}
}
private void WorkerCallback()
{
while (true)
{
if (_packetQueue.Count > 0)
{
byte[] buffer = _packetQueue.Dequeue();
if (buffer != null)
{
try
{
Packet receivedPacket = Packet.ParseIncoming(buffer);
OnPacketReceived(new PacketReceivedEventArgs(receivedPacket));
switch (receivedPacket.Type)
{
case PacketType.Message:
OnMessageReceived(new MessageReceivedEventArgs(receivedPacket.Content));
MessageCallbackPacket packet = new MessageCallbackPacket(receivedPacket.SequenceNumber);
_udpClient.Send(packet.Bytes);
break;
case PacketType.CommandCallback:
if (MessageBuffer[receivedPacket.SequenceNumber] == null)
MessageBuffer[receivedPacket.SequenceNumber] = new PacketBuffer(receivedPacket);
else
MessageBuffer[receivedPacket.SequenceNumber].AddPacket(receivedPacket);
if (MessageBuffer[receivedPacket.SequenceNumber].IsComplete)
OnCommandCallback(new CommandCallbackEventArgs(MessageBuffer[receivedPacket.SequenceNumber].GetContent()));
break;
}
}
catch (ArgumentException) { }
catch (OverflowException) { }
catch (FormatException) { }
}
}
}
}

This is usually because you are not consuming your datagrams fast enough, so in-kernel socket buffer gets full and the network stack starts dropping newly arriving packets. Some points:
Increase the receive buffer on the socket,
Don't acquire locks on every iteration - read as much as you can, then put data into the queue,
Consider non-blocking approach instead of threads.

Unable to connect to other instances of the same program via TCP

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