Develop Reference

C# UdpClient Receive works, ReceiveAsync hangs

I'm currently trying to refactor some old code and reached a point where I'm trying to get UDP communication asynchronous. My old code receives packets:
ClientListener = new UdpClient(ClientListenPort);
ServerEp = new IPEndPoint(IPAddress.Any, ClientListenPort);
try
{
while (!stop)
{
byte[] ReceivedData = ClientListener.Receive(ref ServerEp);
LastReceivedTimeMS = Environment.TickCount;
if (!FoundServer)
{
ServerIP = ServerEp.Address.ToString();
FoundServer = true;
}
HandleReceiveData(ReceivedData);
}
}
catch (Exception e)
{
Debug.Log("Error: " + e);
}
whereas the asynchronous way does not receive anything (hangs). Does someone have an idea what I'm doing wrong?
ClientListener = new UdpClient(ClientListenPort);
ServerEp = new IPEndPoint(IPAddress.Any, ClientListenPort);
try
{
Task.Run(async () =>
{
while (!stop)
{
UdpReceiveResult receivedResults = await ClientListener.ReceiveAsync();
if (!FoundServer)
{
ServerIP = receivedResults.RemoteEndPoint.Address.ToString();
ServerEp = receivedResults.RemoteEndPoint;
FoundServer = true;
}
HandleReceiveData(receivedResults.Buffer);
}
});
}
catch (Exception e)
{
Debug.Log("Error: " + e);
}

My server crashes when I close my client

Using visual studios Windows forms on c#, I'm making a chatprogram with unlimited clients and one server. The server has to be activated before I connect any client. However, after connecting one or more clients and closing one of them, the server crashes. I can nor close it or send any data from my clients to it without getting an error. The CPU usage of my computer rises to 50% during the crash. After I manage to close the server through task manager, different code lines are highlighted, indicating the error.
Here's my server code:
namespace TCPa
{ // skapar en lista med tcp clients
// säg till så att send funktioner tar tcp clients som input i
metoderna och referera till metoderna
// och loopa genom listan, som kallar metoden i lista.
public partial class Server : Form
{
TcpClient klient = null;
List<TcpClient> klientLista = new List<TcpClient>();
TcpListener lyssnare;
int port = 0;
public Server()
{
InitializeComponent();
}
private void btnTaEmot_Click(object sender, EventArgs e)
{
try
{
port = int.Parse(tbxPort.Text);
if (port >= 1024 && port <= 65535)
{
les(port);
}
else
{
MessageBox.Show("Skriv in ett giltigt portnummer mellan 1024 och 65535");
}
}
catch (Exception)
{
MessageBox.Show("Skriv in ett giltigt portnummer mellan 1024 och 65535");
}
}
public void les(int portT)
{
btnTaEmot.Enabled = false;
tbxPort.Enabled = false;
try
{
lyssnare = new TcpListener(IPAddress.Any, portT);
lyssnare.Start();
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
StartAccepting();
}
public async void StartAccepting()
{
try
{
klient = await lyssnare.AcceptTcpClientAsync();
klientLista.Add(klient);
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
StartReading(klient);
StartAccepting();
}
public async void StartReading(TcpClient k)
{
byte[] buffer = new byte[1024];
int n = 0;
try
{
///NEW
n = await k.GetStream().ReadAsync(buffer, 0, 1024);
if (n <= 0)
{
klient.Close();
}
////NEW
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
StartSending(k, Encoding.Unicode.GetString(buffer, 0, n));
tbxLogg.AppendText(Encoding.Unicode.GetString(buffer, 0, n));
StartReading(k);
}
public async void StartSending(TcpClient klientSomSkickar, string message)
{
if (klientLista.Count > 0)
{
byte[] utData = Encoding.Unicode.GetBytes(message);
foreach (TcpClient klient in klientLista)
{
try
{
if (klient != klientSomSkickar)
{
await klient.GetStream().WriteAsync(utData, 0, utData.Length);
}
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text); return;
}
}
}
}
private void Server_FormClosing(object sender, FormClosingEventArgs e)
{
lyssnare.Stop();
if (klient != null && klient.Connected)
{
klient.Close();
}
}
}
}
Here's my client code
namespace Klient
{
public partial class Klient : Form
{
TcpClient klient = new TcpClient();
public Klient()
{
InitializeComponent();
btnSend.Enabled = false;
}
private void btnAnslut_Click(object sender, EventArgs e)
{
Connect();
}
private async void Connect()
{
IPAddress adress = IPAddress.Parse(tbxIP.Text);
int port = int.Parse(tbxPort.Text);
try
{
await klient.ConnectAsync(adress, port);
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
if (klient.Connected)
{
btnAnslut.Enabled = false;
btnSend.Enabled = true;
tbxNmn.Enabled = false;
tbxMedd.Focus();
}
StartReading(klient);
}
private async void btnSend_Click(object sender, EventArgs e)
{
if (klient.Connected)
{
string namn = tbxNmn.Text;
string tid = DateTime.Now.ToString("HH:mm tt");
if (String.IsNullOrEmpty(tbxMedd.Text) || String.IsNullOrWhiteSpace(tbxMedd.Text))
{
MessageBox.Show("Skriv in ditt meddelande");
}
else
{
byte[] utData = Encoding.Unicode.GetBytes("<" + " " + namn + " " + ">" + " " + tid + ":" + "\t" + tbxMedd.Text + "\r\n");
try
{
tbxLogg.AppendText("<" + " " + namn + " " + ">" + " " + tid + ":" + "\t" + tbxMedd.Text + "\r\n");
await klient.GetStream().WriteAsync(utData, 0, utData.Length);
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
}
}
tbxMedd.Clear();
}
public async void StartReading(TcpClient k)
{
byte[] buffer = new byte[1024];
int n = 0;
try
{
n = await k.GetStream().ReadAsync(buffer, 0, 1024);
}
catch (Exception error)
{
MessageBox.Show(error.Message, Text);
return;
}
tbxLogg.AppendText(Encoding.Unicode.GetString(buffer, 0, n));
StartReading(k);
}
private void Klient_FormClosing(object sender, FormClosingEventArgs e)
{
if (klient != null)
klient.Close();
}
}
}
Any help is appreciated!!

An unhandled exception of type 'System.Net.Sockets.SocketException' occurred in System.dll

So I have searched a lot of areas for this answer and I am confused on what this error is doing. Whenever I press the start server button...
...I get this error "An unhandled exception of type 'System.Net.Sockets.SocketException' occurred in System.dll"
My code is quite long but I have no clue what to do...
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
using System.Net;
using System.Net.Sockets;
using System.IO;
namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
private bool isserver = false;
public const int MAXSIZE = 10;
public Form1()
{
InitializeComponent();
clearoutput();
}
TcpListener tcpl = new TcpListener(IPAddress.Parse(getip()), 2546);
List<TcpClient> clients = new List<TcpClient>();
List<string> names = new List<string>();
bool CommandMode = false;
List<string> banlist = new List<string>();
TcpClient Client = new TcpClient();
//client setup
private void button1_Click(object sender, EventArgs e)
{
try {
Output.Text = Output.Text + "You have joined as a client";
Client = new TcpClient();
Client.Connect(IP_address.Text, 2546);
Thread myThread = new Thread(new ParameterizedThreadStart(Listen));
myThread.Start(Client);
//whenever you send a message you must include the next two lines
//Client.GetStream().Write(new byte[] { (byte)Encoding.Unicode.GetByteCount(name + " has joined") }, 0, 1);
//Client.GetStream().Write(Encoding.Unicode.GetBytes(name + " has joined"), 0, Encoding.Unicode.GetByteCount(name + " has joined"));
//the two lines above
Client.GetStream().Write(new byte[] { (byte)Encoding.Unicode.GetByteCount("\\join" + getip()) }, 0, 1);
Client.GetStream().Write(Encoding.Unicode.GetBytes("\\join" + getip()), 0, Encoding.Unicode.GetByteCount("\\join" + getip()));
}
catch { }
IP_address.Visible = false;
Join_btn.Visible = false;
Start_btn.Visible = false;
Output.Visible = true;
Input.Visible = true;
text1.Visible = true;
text1.Visible = true;
}
private void clearoutput()
{
Output.Text = "";
}
//server setup---
private void Start_btn_Click(object sender, EventArgs e)
{
isserver = true;
server_IP_lbl.Text = $"Since you are a server:\nYour ip address is : "+getip();
//if You need a new banlist make sure you click here and allow this
Write_to_output("you are a server");
try
{
StreamReader readerfrban = new StreamReader("banlist");
readerfrban.Close();
Write_to_output("we found a banlist \n no worries");
}
catch
{
Write_to_output("Error- could not find a banlist creating one now");
StreamWriter banlistmaker = new StreamWriter("banlist");
banlistmaker.Close();
}
//open banlist
StreamReader readerforban = new StreamReader("banlist");
string reader = "";
//read all bans in
do
{
reader = readerforban.ReadLine();
if (reader != null)
banlist.Add(reader);
} while (reader != null);
tcpl.Start();
//Thread AcceptSocketsThread = new Thread(AcceptSockets);
//AcceptSocketsThread.Start();
/* while (true)
{
string Message = Console.ReadLine();
if (Message.StartsWith("\\Kick"))
{
Console.Clear();
CommandMode = true;
int clientID = 0;
foreach (TcpClient client in clients)
{
Write_to_output(clientID.ToString() + ") " + names[clientID] + " " + client.Client.RemoteEndPoint);
clientID++;
}
Write_to_output("\n\n Enter the number of the person you want to kick");
TcpClient toRemove = clients[Convert.ToInt32(Console.ReadLine())];
toRemove.Close();
clients.Remove(toRemove);
CommandMode = false;
}
else if (Message.StartsWith("\\Reset"))
{
foreach (TcpClient client in clients)
{
client.Close();
}
clients.Clear();
Write_to_output("KICKED EVERY BODY");
}
else if (Message.StartsWith("\\ban"))
{
Console.Clear();
CommandMode = true;
int clientID = 0;
foreach (TcpClient client in clients)
{
Write_to_output(clientID.ToString() + ") " + names[clientID] + " " + client.Client.RemoteEndPoint);
clientID++;
}
Write_to_output("\n\n Enter the number of the person you want to kick and ban");
TcpClient toRemove = clients[Convert.ToInt32(Console.ReadLine())];
banlist.Add(toRemove.Client.RemoteEndPoint.ToString().Split(new char[] { ':' })[0]);
toRemove.Close();
clients.Remove(toRemove);
CommandMode = false;
}
//starts game
else
{
foreach (TcpClient client in clients)
{
SendMessage(Message, client);
}
}
}*/
IP_address.Visible = false;
Join_btn.Visible = false;
Start_btn.Visible = false;
Output.Visible = true;
Input.Visible = true;
text1.Visible = true;
text1.Visible = true;
}
void SendMessage(string message, TcpClient reciever)
{
try {
reciever.GetStream().Write(new byte[] { (byte)Encoding.Unicode.GetByteCount(message) }, 0, 1);
reciever.GetStream().Write(Encoding.Unicode.GetBytes(message), 0, Encoding.Unicode.GetByteCount(message));
}
catch
{
Write_to_output("Was unable to send to any users error code 1.0.0.0");
}
}
void AcceptSockets()
{
while (true)
{
TcpClient client = tcpl.AcceptTcpClient();
Thread myThread = new Thread(new ParameterizedThreadStart(Listen));
clients.Add(client);
myThread.Start(client);
}
}
void setname(string name)
{
names.Add(name);
}
void Listen(object obj)
{
TcpClient TCPClient = (TcpClient)obj;
while (true)
{
try
{
byte[] fBuffer = new byte[1];
TCPClient.GetStream().Read(fBuffer, 0, 1);
byte[] buffer = new byte[(int)fBuffer[0]];
TCPClient.GetStream().Read(buffer, 0, (int)fBuffer[0]);
string message = Encoding.Unicode.GetString(buffer).Trim();
if (message.StartsWith("\\join"))
{
message = message.Remove(0, 5);
int a = 0;
for (int i = 0; i < banlist.Count; i++)
{
if (message.StartsWith(banlist[i]))
{
a = 1;
}
}
if (a == 0)
{
//int namespaceer = 0;
//foreach (char chars in message)
//{
// namespaceer += 1;
// if (chars == '+')
// break;
//}
// message = message.Remove(0, namespaceer);
}
else
{
//Write_to_output("Person on banlist");
// TcpClient toRemove = clients[Convert.ToInt32(Console.ReadLine())];
//toRemove.Close();
}
}
else
{
foreach (TcpClient client in clients)
{
if (client != TCPClient)
{
SendMessage(message, client);
}
}
if (!CommandMode)
{
Write_to_output(message.Trim());
}
else
{
}
}
}
catch (Exception e)
{
Write_to_output(e.ToString());
}
}
}
static string getip()
{
IPHostEntry host;
string localIP = "?";
host = Dns.GetHostEntry(Dns.GetHostName());
foreach (IPAddress ip in host.AddressList)
{
if (ip.AddressFamily.ToString() == "InterNetwork")
{
localIP = ip.ToString();
}
}
return localIP;
}
public void Write_to_output(string towrite)
{
//check outputs length
int numLines = 0;
string text = Output.Text;
numLines = Text.Split('\n').Length;
if (numLines == MAXSIZE)
{
Output.Text = towrite;
}
else
{
Output.Text = Output.Text + $"\n" + towrite;
}
}
private void Input_Leave(object sender, EventArgs e)
{
string message = Input.Text;
if (isserver == false)
{
//send client code
SendMessage(message,Client);
}
else
{
//send server code
foreach (TcpClient client in clients)
{
SendMessage(message, client);
}
}
}
}
}
Please help me...

Check if the port TCP 2546 is not busy by another process or code instance on the listening machine.
Or choose another free port to listen to.

"A socket operation failed because the destination host was down" when connecting pc to mobie device

My project is to connecting pc with mobile device using 32feet.net library.
Until Now, my solution is doing steps like:
Scanning for devices in area.
pairing with selected device .
request pairing with mobile device and when it's okay this error appear :
"A socket operation failed because the destination host was down" and I don't know why and how to overcome this problem. Any help with this problem will be appreciated.
And my solution is:
namespace Bluetooth
{
public partial class Form1 : Form
{
List<string> items;
public Form1()
{
items = new List<string>();
InitializeComponent();
}
private void Connect_Click(object sender, EventArgs e)
{
if(ServerStarted )
{
updateUI("Server Already Started");
return;
}
if(rbClient.Checked)
{
//ConnectAsClient();
StartScan();
}
else
{
ConnectAsServer();
}
}
private void StartScan()
{
listBox.DataSource = null;
listBox.Items.Clear();
items.Clear();
Thread bluethoothscanthread = new Thread(new ThreadStart(scan));
bluethoothscanthread.Start();
}
BluetoothDeviceInfo[] devices;
private void scan()
{
updateUI("Starting Scan ...");
BluetoothClient client = new BluetoothClient();
devices = client.DiscoverDevicesInRange();
updateUI("Scan Completed......");
updateUI(devices.Length.ToString() + "devices discovered");
foreach(BluetoothDeviceInfo d in devices)
{
items.Add(d.DeviceName);
}
UpdateDeviceList();
}
private void ConnectAsServer()
{
Thread BluethoothServerThread = new Thread(new ThreadStart(ServerConnectThread));
BluethoothServerThread.Start();
}
private void ConnectAsClient()
{
throw new NotImplementedException();
}
Guid mUUID = new Guid("00001101-0000-1000-8000-00805F9B34FB");
bool ServerStarted = false;
public void ServerConnectThread()
{
ServerStarted = true;
updateUI("Server Started , Waiting For Clients ");
BluetoothListener bluelistner = new BluetoothListener(mUUID);
bluelistner.Start();
BluetoothClient conn = bluelistner.AcceptBluetoothClient();
updateUI("Client has connected");
Stream mstream = conn.GetStream();
while(true)
{
// handle server connection
try
{
byte[] Received = new byte[1024];
mstream.Read(Received, 0, Received.Length);
updateUI("Received : " + Encoding.ASCII.GetString(Received));
byte[] Sent = Encoding.ASCII.GetBytes("Hello World ");
mstream.Write(Sent, 0, Sent.Length);
}
catch(IOException exception)
{
updateUI("Client has disconnected !!! ");
}
}
}
private void updateUI(string message)
{
Func<int> del = delegate ()
{
tbOutput.AppendText(message + System.Environment.NewLine);
return 0 ;
};
Invoke(del);
}
private void UpdateDeviceList()
{
Func<int> del = delegate ()
{
listBox.DataSource = items;
return 0;
};
Invoke(del);
}
BluetoothDeviceInfo deviceinfo;
private void listBox_DoubleClick(object sender, EventArgs e)
{
deviceinfo = devices.ElementAt(listBox.SelectedIndex);
updateUI(deviceinfo.DeviceName + "Was Selected , attempting connect");
if( pairDevice())
{
updateUI("Device Paired.....");
updateUI("Starting Connect Thread");
Thread bluethoothClientThread = new Thread(new ThreadStart(ClientconnectThread));
bluethoothClientThread.Start();
}
else
{
updateUI("Pair Failed");
}
}
private void ClientconnectThread()
{
BluetoothClient client = new BluetoothClient();
updateUI("Attempting Connect");
client.BeginConnect(deviceinfo.DeviceAddress, mUUID, this.BluetoothClientConnectCallback, client);
}
void BluetoothClientConnectCallback(IAsyncResult result)
{
BluetoothClient client = (BluetoothClient)result.AsyncState;
BluetoothEndPoint bep = new BluetoothEndPoint(deviceinfo.DeviceAddress, BluetoothService.AvctpProtocol);
BluetoothClient cli = new BluetoothClient();
client.Connect(bep); // the exception throw in this line //
Stream stream = cli.GetStream();
stream.ReadTimeout = 10000;
//Stream peerStream = cli.GetStream();
// client.Connect(BluetoothAddress.Parse(items(0)), mUUID);
//client.EndConnect(result);
//while(true)
//{
// while (!ready) ;
// stream.Write(message, 0, message.Length);
//}
//streaming(result);
if(result.IsCompleted)
{
// client.EndConnect(result);
// Stream stream = client.GetStream();
// stream.ReadTimeout = 1000;
updateUI("Ya rabbbbb");
//while (!ready) ;
//stream.Write(message, 0, message.Length);
}
}
void streaming (IAsyncResult result)
{
BluetoothListener listn = new BluetoothListener(mUUID);
listn.Start();
BluetoothClient conn = listn.AcceptBluetoothClient();
Stream peerstream = conn.GetStream();
bool rightconn = peerstream.CanRead;
if(rightconn)
{
updateUI("Now you can streaming");
}
else
{
updateUI("Not Yet");
}
}
string mypin = "1234";
private bool pairDevice()
{
if(!deviceinfo.Authenticated)
{
if (!BluetoothSecurity.PairRequest(deviceinfo.DeviceAddress, mypin))
{
return false;
}
}
return true;
}
bool ready = false;
byte[] message;
private void tbText_KeyPress(object sender, KeyPressEventArgs e)
{
if(e.KeyChar == 13)
{
message = Encoding.ASCII.GetBytes(tbText.Text);
ready = true;
tbText.Clear();
}
}
}
} // End of namespace

I think I followed same example with you and of course I encountered same problem.
Rest of my codes are same with yours until "private void ClientconnectThread()" function and here is mine;
private void ClientConnectThread()
{
BluetoothClient client = new BluetoothClient();
updateUI("attempting connect");
//client.BeginConnect(deviceInfo.DeviceAddress, mUUID, this.BluetoothClientConnectCallback, client);
BluetoothAddress addressSeleccionado = deviceInfo.DeviceAddress;
Guid mUUID = new Guid("00001101-0000-1000-8000-00805F9B34FB");
BluetoothEndPoint ep = new BluetoothEndPoint(addressSeleccionado, mUUID);
client.Connect(ep);
updateUI("connected");
Stream stream = client.GetStream();
while (true)
{
byte[] received = new byte[1024];
stream.Read(received, 0, received.Length);
updateUI("received: ");
for (int i = 0; i < 15; i++)
{
updateUI(received[i].ToString());
}
if (ready)
{
ready = false;
stream.Write(message, 0, message.Length);
}
}
}
With this code I can connect the remote device and implement basic send/receive data communication. In order to my search over internet, "if this code does not fit for you", you might think that 32feet is not compatible with your bluetooth driver. (by the way my PC's OS is 64bit Win7 and I use the internal BT device of my PC )
Best regards.

Async chat server buffer issue

can someone please help me out with this... I've been struggling all day.
So I'm trying to learn Async sockets which is something that's been giving me trouble.
The issue is basically the way I'm updating the ListBox with people who have joined the chat room's names:
Basically what I'm doing is having each client send "!!addlist [nickname]" when they join the server.
It's not ideal as it doesn't check for duplicates etc. but now I just want to know why it won't work.
Whenever somebody adds a name they haven't seen before, they will also send "!!addlist [nick]"
In this way, every time someone joins, the lists should be updated for everyone.
The issue seems to be that all the clients start communicating at the same time and it interferes with the buffer.
I've tried using a separate buffer for every client so that's not the issue.
I've tried using lock() but that doesn't seem to be working either.
Essentially what happens is the buffers seem to truncate; where there is data from two different people in the same buffer.
Please just tell me what I'm doing wrong with the buffers or on the client side:
Note that the async socket is using Send instead of BeginSend.
I've tried both methods and they run into the same issue... so it's probably client side?
public partial class Login : Form
{
private ChatWindow cw;
private Socket serverSocket;
private List<Socket> socketList;
private byte[] buffer;
private bool isHost;
private bool isClosing;
public void startListening()
{
try
{
this.isHost = true; //We're hosting this server
cw.callingForm = this; //Give ChatForm the login form (this) [that acts as the server]
cw.Show(); //Show ChatForm
cw.isHost = true; //Tell ChatForm it is the host (for display purposes)
this.Hide(); //And hide the login form
serverSocket.Bind(new IPEndPoint(IPAddress.Any, int.Parse(portBox.Text))); //Bind to our local address
serverSocket.Listen(1); //And start listening
serverSocket.BeginAccept(new AsyncCallback(AcceptCallback), null); //When someone connects, begin the async callback
cw.connectTo("127.0.0.1", int.Parse(portBox.Text), nicknameBox.Text); //And have ChatForm connect to the server
}
catch (Exception) { /*MessageBox.Show("Error:\n\n" + e.ToString());*/ } //Let us know if we ran into any errors
}
public void AcceptCallback(IAsyncResult AR)
{
try
{
Socket s = serverSocket.EndAccept(AR); //When someone connects, accept the new socket
socketList.Add(s); //Add it to our list of clients
s.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), s); //Begin the async receive method using our buffer
serverSocket.BeginAccept(new AsyncCallback(AcceptCallback), null); //And start accepting new connections
}
catch (Exception) {}
}
public void ReceiveCallback(IAsyncResult AR) //When a message from a client is received
{
try
{
if (isClosing)
return;
Socket s = (Socket)AR.AsyncState; //Get the socket from our IAsyncResult
int received = s.EndReceive(AR); //Read the number of bytes received (*need to add locking code here*)
byte[] dbuf = new byte[received]; //Create a temporary buffer to store just what was received so we don't have extra data
Array.Copy(buffer, dbuf, received); //Copy the received data from our buffer to our temporary buffer
foreach (Socket client in socketList) //For each client that is connected
{
try
{
if (client != (Socket)AR.AsyncState) //If this isn't the same client that just sent a message (*client handles displaying these*)
client.Send(dbuf); //Send the message to the client
}
catch (Exception) { }
} //Start receiving new data again
s.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), s);
}
catch (Exception) { /*cw.output("\n\nError:\n\n" + e.ToString());*/ }
}
public void SendCallback(IAsyncResult AR)
{
try
{
Socket s = (Socket)AR.AsyncState;
s.EndSend(AR);
}
catch (Exception) { /*cw.output("\n\nError:\n\n" + e.ToString());*/ }
}
Here is the client side:
public void getData()
{
try
{
byte[] buf = new byte[1024];
string message = "";
while(isConnected)
{
Array.Clear(buf, 0, buf.Length);
message = "";
clientSocket.Receive(buf, buf.Length, SocketFlags.None);
message = Encoding.ASCII.GetString(buf);
if (message.StartsWith("!!addlist"))
{
message = message.Replace("!!addlist", "");
string userNick = message.Trim();
if (!namesBox.Items.Contains(userNick))
{
addNick(userNick.Trim());
}
continue;
}
else if (message.StartsWith("!!removelist"))
{
message = message.Replace("!!removelist", "");
string userNick = message.Trim();
removeNick(userNick);
output("Someone left the room: " + userNick);
continue;
}
else if (!namesBox.Items.Contains(message.Substring(0, message.IndexOf(":"))))
{
addNick(message.Substring(0, message.IndexOf(":")).Trim()); //So they at least get added when they send a message
}
output(message);
}
}
catch (Exception)
{
output("\n\nConnection to the server lost.");
isConnected = false;
}
}
Here is my addNick function that seems to fix some things?
public void addNick(string n)
{
if (n.Contains(" ")) //No Spaces... such a headache
return;
if (n.Contains(":"))
return;
bool shouldAdd = true;
n = n.Trim();
for (int x = namesBox.Items.Count - 1; x >= 0; --x)
if (namesBox.Items[x].ToString().Contains(n))
shouldAdd = false;
if (shouldAdd)
{
namesBox.Items.Add(n);
output("Someone new joined the room: " + n);
sendRaw("!!addlist " + nickName);
}
}
I think the issue is that some of the packets are being skipped?
Maybe there's too much code in the client after Receive before it gets called again?
Should I create a separate thread for each message so that receive runs constantly? (Dumb)
Should I have my client use Async receives and sends as well?
I have a feeling that is the answer ^
With all of the checks I do, I managed to clean up the duplicate name issue... but i regularly receive messages with spaces and partial messages from other clients it seems.

Okay so, after messing with this for a long time, I have it relatively stable.
For starters, I added the following state object:
public class StateObject
{
public Socket workSocket = null;
public const int BufferSize = 1024;
public byte[] buffer = new byte[BufferSize];
public StringBuilder sb = new StringBuilder();
public bool newConnection = true;
}
This makes it easy to keep track of each connection and gives each connection its own buffer.
The second thing I did was look for a new line in each message.
I wasn't looking for this in the original code and I believe this was the root of most issues.
I also gave the responsibility of dealing with username management to the server; something that I should have done from the start obviously.
Here is the current server code:
This code is in no way perfect and I'm continuously finding new errors the more I try to break it. I'm going to keep messing with it for awhile but at the moment, it seems to work decently.
public partial class Login : Form
{
private ChatWindow cw;
private Socket serverSocket;
private List<Socket> socketList;
private byte[] buffer;
private bool isHost;
private bool isClosing;
private ListBox usernames;
public Login()
{
InitializeComponent();
}
private void Login_Load(object sender, EventArgs e)
{
ipLabel.Text = getLocalIP();
cw = new ChatWindow();
serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
socketList = new List<Socket>();
buffer = new byte[1024];
isClosing = false;
usernames = new ListBox();
}
public string getLocalIP()
{
return Dns.GetHostEntry(Dns.GetHostName()).AddressList.FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork).ToString();
}
private void joinButton_Click(object sender, EventArgs e)
{
try
{
int tryPort = 0;
this.isHost = false;
cw.callingForm = this;
if (ipBox.Text == "" || portBox.Text == "" || nicknameBox.Text == "" || !int.TryParse(portBox.Text.ToString(), out tryPort))
{
MessageBox.Show("You must enter an IP Address, Port, and Nickname to connect to a server.", "Missing Info");
return;
}
this.Hide();
cw.Show();
cw.connectTo(ipBox.Text, int.Parse(portBox.Text), nicknameBox.Text);
}
catch(Exception otheree) {
MessageBox.Show("Error:\n\n" + otheree.ToString(),"Error connecting...");
cw.Hide();
this.Show();
}
}
private void hostButton_Click(object sender, EventArgs e)
{
int tryPort = 0;
if (portBox.Text == "" || nicknameBox.Text == "" || !int.TryParse(portBox.Text.ToString(), out tryPort)) {
MessageBox.Show("You must enter a Port and Nickname to host a server.", "Missing Info");
return;
}
startListening();
}
public void startListening()
{
try
{
this.isHost = true; //We're hosting this server
cw.callingForm = this; //Give ChatForm the login form (this) [that acts as the server]
cw.Show(); //Show ChatForm
cw.isHost = true; //Tell ChatForm it is the host (for display purposes)
this.Hide(); //And hide the login form
serverSocket.Bind(new IPEndPoint(IPAddress.Any, int.Parse(portBox.Text))); //Bind to our local address
serverSocket.Listen(1); //And start listening
serverSocket.BeginAccept(new AsyncCallback(AcceptCallback), null); //When someone connects, begin the async callback
cw.connectTo("127.0.0.1", int.Parse(portBox.Text), nicknameBox.Text); //And have ChatForm connect to the server
}
catch (Exception) {}
}
public void AcceptCallback(IAsyncResult AR)
{
try
{
StateObject state = new StateObject();
state.workSocket = serverSocket.EndAccept(AR);
socketList.Add(state.workSocket);
state.workSocket.BeginReceive(state.buffer, 0, StateObject.BufferSize, SocketFlags.None, new AsyncCallback(ReceiveCallback), state);
serverSocket.BeginAccept(new AsyncCallback(AcceptCallback), null);
}
catch (Exception) {}
}
public void ReceiveCallback(IAsyncResult AR)
{
try
{
if (isClosing)
return;
StateObject state = (StateObject)AR.AsyncState;
Socket s = state.workSocket;
String content = "";
int received = s.EndReceive(AR);
if(received > 0)
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, received));
content = state.sb.ToString();
if (content.IndexOf(Environment.NewLine) > -1) //If we've received the end of the message
{
if (content.StartsWith("!!addlist") && state.newConnection)
{
state.newConnection = false;
content = content.Replace("!!addlist", "");
string userNick = content.Trim();
if (isHost && userNick.StartsWith("!"))
userNick = userNick.Replace("!", "");
userNick = userNick.Trim();
if (userNick.StartsWith("!") || userNick == string.Empty || usernames.Items.IndexOf(userNick) > -1)
{
//Invalid Username :c get dropped
s.Send(Encoding.ASCII.GetBytes("Invalid Username/In Use - Sorry :("));
s.Shutdown(SocketShutdown.Both);
s.Disconnect(false);
s.Close();
socketList.Remove(s);
return;
}
usernames.Items.Add(userNick);
foreach (string name in usernames.Items)
{
if (name.IndexOf(userNick) < 0)
{
s.Send(Encoding.ASCII.GetBytes("!!addlist " + name + "\r\n"));
Thread.Sleep(10); //such a hack... ugh it annoys me that this works
}
}
foreach (Socket client in socketList)
{
try
{
if (client != s)
client.Send(Encoding.ASCII.GetBytes("!!addlist " + userNick + "\r\n"));
}
catch (Exception) { }
}
}
else if (content.StartsWith("!!removelist") && !state.newConnection)
{
content = content.Replace("!!removelist", "");
string userNick = content.Trim();
usernames.Items.Remove(userNick);
foreach (Socket client in socketList)
{
try
{
if (client != s)
client.Send(Encoding.ASCII.GetBytes("!!removelist " + userNick + "\r\n"));
}
catch (Exception) { }
}
}
else if (state.newConnection) //if they don't give their name and try to send data, just drop.
{
s.Shutdown(SocketShutdown.Both);
s.Disconnect(false);
s.Close();
socketList.Remove(s);
return;
}
else
{
foreach (Socket client in socketList)
{
try
{
if (client != s)
client.Send(System.Text.Encoding.ASCII.GetBytes(content));
}
catch (Exception) { }
}
}
}
Array.Clear(state.buffer, 0, StateObject.BufferSize);
state.sb.Clear();
s.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);
}
catch (Exception) {
socketList.Remove(((StateObject)AR.AsyncState).workSocket);
}
}
public void SendCallback(IAsyncResult AR)
{
try
{
StateObject state = (StateObject)AR.AsyncState;
state.workSocket.EndSend(AR);
}
catch (Exception) {}
}
private void Login_FormClosed(object sender, FormClosedEventArgs e)
{
try
{
this.isClosing = true;
if (this.isHost)
{
foreach (Socket c in socketList)
{
if (c.Connected)
{
c.Close();
}
}
serverSocket.Shutdown(SocketShutdown.Both);
serverSocket.Close();
serverSocket = null;
serverSocket.Dispose();
}
socketList.Clear();
}
catch (Exception) { }
finally
{
Application.Exit();
}
}
}
public class StateObject
{
public Socket workSocket = null;
public const int BufferSize = 1024;
public byte[] buffer = new byte[BufferSize];
public StringBuilder sb = new StringBuilder();
public bool newConnection = true;
}
The client code (work in progress):
public partial class ChatWindow : Form
{
private Socket clientSocket;
private Thread chatThread;
private string ipAddress;
private int port;
private bool isConnected;
private string nickName;
public bool isHost;
public Login callingForm;
private static object conLock = new object();
public ChatWindow()
{
InitializeComponent();
isConnected = false;
isHost = false;
}
public string getIP() {
return Dns.GetHostEntry(Dns.GetHostName()).AddressList.FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork).ToString();
}
public void displayError(string err)
{
output(Environment.NewLine + Environment.NewLine + err + Environment.NewLine);
}
public void op(string s)
{
try
{
lock (conLock)
{
chatBox.Text += s;
}
}
catch (Exception) { }
}
public void connectTo(string ip, int p, string n) {
try
{
this.Text = "Trying to connect to " + ip + ":" + p + "...";
this.ipAddress = ip;
this.port = p;
this.nickName = n;
clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
if (!isHost)
{
op("Connecting to " + ipAddress + ":" + port + "...");
}
else
{
output("Listening on " + getIP() + ":" + port + "...");
}
clientSocket.Connect(ipAddress, port);
isConnected = true;
if (!isHost)
{
this.Text = "Connected to " + ipAddress + ":" + port + " - Nickname: " + nickName;
output("Connected!");
}
else
{
this.Text = "Hosting on " + getIP() + ":" + port + " - Nickname: " + nickName;
}
chatThread = new Thread(new ThreadStart(getData));
chatThread.Start();
nickName = nickName.Replace(" ", "");
nickName = nickName.Replace(":", "");
if(nickName.StartsWith("!"))
nickName = nickName.Replace("!", "");
namesBox.Items.Add(nickName);
sendRaw("!!addlist " + nickName);
}
catch (ThreadAbortException)
{
//do nothing; probably closing chat window
}
catch (Exception e)
{
if (!isConnected)
{
this.Hide();
callingForm.Show();
clearText();
MessageBox.Show("Error:\n\n" + e.ToString(), "Error connecting to remote host");
}
}
}
public void removeNick(string n)
{
if (namesBox.Items.Count <= 0)
return;
for (int x = namesBox.Items.Count - 1; x >= 0; --x)
if (namesBox.Items[x].ToString().Contains(n))
namesBox.Items.RemoveAt(x);
}
public void clearText()
{
try
{
lock (conLock)
{
chatBox.Text = "";
}
}
catch (Exception) { }
}
public void addNick(string n)
{
if (n.Contains(" ")) //No Spaces... such a headache
return;
if (n.Contains(":"))
return;
bool shouldAdd = true;
n = n.Trim();
for (int x = namesBox.Items.Count - 1; x >= 0; --x)
if (namesBox.Items[x].ToString().Contains(n))
shouldAdd = false;
if (shouldAdd)
{
namesBox.Items.Add(n);
output("Someone new joined the room: " + n);
//sendRaw("!!addlist " + nickName);
}
}
public void addNickNoMessage(string n)
{
if (n.Contains(" ")) //No Spaces... such a headache
return;
if (n.Contains(":"))
return;
bool shouldAdd = true;
n = n.Trim();
for (int x = namesBox.Items.Count - 1; x >= 0; --x)
if (namesBox.Items[x].ToString().Contains(n))
shouldAdd = false;
if (shouldAdd)
{
namesBox.Items.Add(n);
//sendRaw("!!addlist " + nickName);
}
}
public void getData()
{
try
{
byte[] buf = new byte[1024];
string message = "";
while(isConnected)
{
Array.Clear(buf, 0, buf.Length);
message = "";
int gotData = clientSocket.Receive(buf, buf.Length, SocketFlags.None);
if (gotData == 0)
throw new Exception("I swear, this was working before but isn't anymore...");
message = Encoding.ASCII.GetString(buf);
if (message.StartsWith("!!addlist"))
{
message = message.Replace("!!addlist", "");
string userNick = message.Trim();
if(!namesBox.Items.Contains(userNick))
{
addNick(userNick);
}
continue;
}
else if (message.StartsWith("!!removelist"))
{
message = message.Replace("!!removelist", "");
string userNick = message.Trim();
removeNick(userNick);
output("Someone left the room: " + userNick);
continue;
}
output(message);
}
}
catch (Exception)
{
isConnected = false;
output(Environment.NewLine + "Connection to the server lost.");
}
}
public void output(string s)
{
try
{
lock (conLock)
{
chatBox.Text += s + Environment.NewLine;
}
}
catch (Exception) { }
}
private void ChatWindow_FormClosed(object sender, FormClosedEventArgs e)
{
try
{
if(isConnected)
sendRaw("!!removelist " + nickName);
isConnected = false;
clientSocket.Shutdown(SocketShutdown.Receive);
if (chatThread.IsAlive)
chatThread.Abort();
callingForm.Close();
}
catch (Exception) { }
}
private void sendButton_Click(object sender, EventArgs e)
{
if(isConnected)
send(sendBox.Text);
}
private void sendBox_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
if (isConnected)
{
if (sendBox.Text != "")
{
send(sendBox.Text);
sendBox.SelectAll();
e.SuppressKeyPress = true;
e.Handled = true;
}
}
}
}
private void send(string t) {
try
{
byte[] data = System.Text.Encoding.ASCII.GetBytes(nickName + ": " + t + "\r\n");
clientSocket.Send(data);
output(nickName + ": " + t);
}
catch (Exception e)
{
displayError(e.ToString());
}
}
private void sendRaw(string t)
{
try
{
byte[] data = System.Text.Encoding.ASCII.GetBytes(t + "\r\n");
clientSocket.Send(data);
}
catch (Exception e)
{
displayError(e.ToString());
}
}
private void chatBox_TextChanged(object sender, EventArgs e)
{
chatBox.SelectionStart = chatBox.Text.Length;
chatBox.ScrollToCaret();
}
private void sendBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
e.SuppressKeyPress = true;
}
}
To do:
Add invokes, more delegates, do some more QA and find out what breaks it.
Also, I believe there's still the possibility of packet loss due to the client addlist functions being in the read loop. I believe this is why the "crappy hack" using Thread.Sleep(10) in the server callback for name population is an issue.
I think it might be better to either pass the command off to another thread while continuing to read or have the client tell the server it's ready for another name.
Otherwise, there might be some data loss during name updates.
The other thing is that, as was said in the comments above, delegates should be used when updating the UI objects (chatbox and listbox). I wrote the code for these but ultimately removed it because there was no noticeable change and I wanted to keep it simple.
I do still use an object lock when outputting text to the chatbox, but there's no noticeable difference there.
The code should be added as not using delegates is potentially problematic, but I literally caught the chat box in an infinite loop of updates without issue.
I tried breaking it with telnet and was successful so I added a newConnection property to the StateObject to ensure that each client can only send "!!addlist" once.
There are, of course, other ways to abuse the server by creating a client that joins and leaves repeatedly, so ultimately I will probably end up passing the !!removelist handling to the server instead of leaving it up to the client.