Develop Reference

C# Socket connection can't receive more than once

I have a server in C that send message to unity. In Unity, I can receive data once, but when the server sends a new message, unity receives nothing.
For example: Unity can connect to server, receive the first message that said "move right" and move the camera of Unity to the right but then if the server send "move left" or anything else unity is block in the function receive which calls BeginReceive:
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
Code of my server:
void connectToUnity() {
SOCKADDR_IN sin;
WSAStartup(MAKEWORD(2, 0), &WSAData);
sock = socket(AF_INET, SOCK_STREAM, 0);
sin.sin_addr.s_addr = inet_addr("127.0.0.1");
sin.sin_family = AF_INET;
sin.sin_port = htons(53660);
bind(sock, (SOCKADDR*)&sin, sizeof(sin));
listen(sock, 0);
printf("Connexion to unity\n");
}
void sendDataToUnity(const char * mouvement) {
SOCKET csock;
while (1)
{
int sinsize = sizeof(csin);
if ((csock = accept(sock, (SOCKADDR*)&csin, &sinsize)) != INVALID_SOCKET)
{
send(csock, mouvement, 14, 0);
printf("Donnees envoyees \n");
return;
}
else {
printf("Rien n'a ete envoye");
}
}
}
Code in Unity:
public bool ConnectToServer(string hostAdd, int port)
{
//connect the socket to the server
try
{
//create end point to connect
conn = new IPEndPoint(IPAddress.Parse(hostAdd), port);
//connect to server
clientSocket.BeginConnect(conn, new AsyncCallback(ConnectCallback), clientSocket);
socketReady = true;
connectDone.WaitOne();
Debug.Log("Client socket ready: " + socketReady);
// Receive the response from the remote device.
Receive(clientSocket);
//receiveDone.WaitOne();
}
catch (Exception ex)
{
Debug.Log("socket error: " + ex.Message);
}
return socketReady;
}
//async call to connect
static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket
Socket client = (Socket)ar.AsyncState;
// Complete the connection
client.EndConnect(ar);
Debug.Log("Client Socket connected to: " + client.RemoteEndPoint);
connectDone.Set();
}
catch (Exception e)
{
Debug.Log("Error connecting: " + e);
}
}
private static void Receive(Socket client)
{
try
{
Debug.Log("Try to receive");
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Debug.Log(e);
}
}
static void ReceiveCallback(IAsyncResult ar)
{
try
{
//Read data from the remote device.
Debug.Log("receive callback");
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
Debug.Log("Il y a une réponse");
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
response = state.sb.ToString();
Debug.Log(response);
//client.Shutdown(SocketShutdown.Both);
}
else
{
if(state.sb.Length > 1)
{
response = state.sb.ToString();
Debug.Log(response);
}
}
}
catch (Exception ex)
{
Debug.Log("Error: " + ex.Message);
}
}
The function receive is called once in the function ConnectToServer, then I tried to call again in the update like this:
void Update()
{
if (response.Contains("right"))
{
Debug.Log("Move to the right ");
float x = Camera.main.transform.localEulerAngles.x;
float y = Camera.main.transform.localEulerAngles.y;
DeplacementCamera.moveRight(x, y);
response = "";
Receive(clientSocket);
}
}
I have already see this post but without success or maybe I tried it in the wrong way:
Why does BeginReceive() not return for more than one read?
Edit: In the function ReceiveCallback the else is never reached.

you may change your method
private void SetupReceiveCallback(Socket sock)
{
try
{
DataBuffer = new byte[BufferSize];
AsyncCallback recieveData = new AsyncCallback(OnRecievedData);
sock.BeginReceive(DataBuffer, 0, DataBuffer.Length, SocketFlags.None, recieveData, _socket);
}
catch (Exception E)
{
}
}
private void OnRecievedData(IAsyncResult ar)
{
Socket sock = (Socket)ar.AsyncState;
try
{
if (sock.Connected)
{
int nBytesRec = sock.EndReceive(ar);
if (nBytesRec > 0)
{
string Data = Encoding.UTF8.GetString(DataBuffer);
if (Data.Length != 4)
{
string JsonString = Data;
if (!string.IsNullOrEmpty(JsonString))
{
try
{
//Add you code processing here
}
catch (Exception ex)
{
}
}
BufferSize = 4;
}
else
{
BufferSize = BitConverter.ToInt32(DataBuffer, 0);
}
}
SetupReceiveCallback(sock);
}
else
// on not connected to socket
}
catch (Exception E)
{
}
}
public bool Connect(string IP, int Port)
{
try
{
_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//if (IsValidIP(IP))
//{
// IPEndPoint epServer = new IPEndPoint(IPAddress.Parse(IP), Port);
// _socket.Connect(epServer);
//}
//else
//{
// _socket.Connect(IP, Port);
//}
//SetupReceiveCallback(_socket);
}
catch(Exception ex)
{
}
return false;
}

C# using Socket to send message to all client

My objective here to to send a message to the connected clients from my server. The code is working but the only problem is, it can only send message to the client who sent the command. What I need is to received the message by other client. I saw this code in youtube and make a few adjustment. Please find below.
Server Code
class Program
{
private static readonly Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private static readonly List<Socket> clientSockets = new List<Socket>();
private const int BUFFER_SIZE = 2048;
private const int PORT = 100;
private static readonly byte[] buffer = new byte[BUFFER_SIZE];
static void Main(string[] args)
{
Console.Title = "Server";
SetupServer();
Console.ReadLine(); // When we press enter close everything
CloseAllSockets();
}
private static void SetupServer()
{
Console.WriteLine("Setting up server...");
serverSocket.Bind(new IPEndPoint(IPAddress.Any, PORT));
serverSocket.Listen(0);
serverSocket.BeginAccept(AcceptCallback, null);
Console.WriteLine("Server setup complete");
}
/// <summary>
/// Close all connected client (we do not need to shutdown the server socket as its connections
/// are already closed with the clients).
/// </summary>
private static void CloseAllSockets()
{
foreach (Socket socket in clientSockets)
{
socket.Shutdown(SocketShutdown.Both);
socket.Close();
}
serverSocket.Close();
}
private static void AcceptCallback(IAsyncResult AR)
{
Socket socket;
try
{
socket = serverSocket.EndAccept(AR);
}
catch (ObjectDisposedException) // I can not seem to avoid this (on exit when properly closing sockets)
{
return;
}
clientSockets.Add(socket);
socket.BeginReceive(buffer, 0, BUFFER_SIZE, SocketFlags.None, ReceiveCallback, socket);
Console.WriteLine("{0}", socket.RemoteEndPoint + " connected...");
serverSocket.BeginAccept(AcceptCallback, null);
}
private static void ReceiveCallback(IAsyncResult AR)
{
Socket current = (Socket)AR.AsyncState;
int received;
try
{
received = current.EndReceive(AR);
}
catch (SocketException)
{
Console.WriteLine("Client forcefully disconnected");
// Don't shutdown because the socket may be disposed and its disconnected anyway.
current.Close();
clientSockets.Remove(current);
return;
}
byte[] recBuf = new byte[received];
Array.Copy(buffer, recBuf, received);
string text = Encoding.ASCII.GetString(recBuf);
Console.WriteLine("Received Text: " + text);
if (text.ToLower() == "meeting") // Client requested time
{
foreach (Socket socket in clientSockets)
{
//current = socket;
string message = "meeting";
byte[] data = Encoding.ASCII.GetBytes(message);
socket.Send(data);
//socket.BeginSend(data, 0, data.Length, SocketFlags.None, null, null);
Console.WriteLine("Meeting invite sent to " + socket.RemoteEndPoint);
}
}
else if (text.ToLower() == "exit") // Client wants to exit gracefully
{
// Always Shutdown before closing
Console.WriteLine(current.RemoteEndPoint + " disconnected");
current.Shutdown(SocketShutdown.Both);
current.Close();
clientSockets.Remove(current);
return;
}
else
{
Console.WriteLine("Invalid request");
byte[] data = Encoding.ASCII.GetBytes("Invalid request");
current.Send(data);
Console.WriteLine("Warning Sent");
}
current.BeginReceive(buffer, 0, BUFFER_SIZE, SocketFlags.None, ReceiveCallback, current);
}
}
Client Code
namespace TCP_Client {
public partial class frmTCPClient : Form
{
private readonly Socket ClientSocket = new Socket
(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private const int PORT = 100;
private byte[] buffer;
private string message { get; set; }
public string serverMessage { get; set; }
public frmTCPClient()
{
InitializeComponent();
}
private void frmTCPClient_Load(object sender, EventArgs e)
{
ConnectToServer();
//UpdateControls();
}
private void UpdateControls()
{
lblMessage.Text = message;
//txtFromServer.Text = serverMessage;
}
private void ConnectToServer()
{
int attempts = 0;
while (!ClientSocket.Connected)
{
try
{
attempts++;
//lblMessage.Text = "Connection attempt " + attempts;
// Change IPAddress.Loopback to a remote IP to connect to a remote host.
//ClientSocket.Connect(IPAddress.Loopback, PORT);
ClientSocket.Connect("172.20.110.129", PORT);
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message + Environment.NewLine + "Connection attempt " + attempts);
}
}
message = "Connected";
}
private void RequestLoop()
{
while (true)
{
SendRequest("");
ReceiveResponse();
}
}
private void SendRequest(string text)
{
string request = text;
SendString(request);
if (request.ToLower() == "exit")
{
Exit();
}
}
/// <summary>
/// Sends a string to the server with ASCII encoding.
/// </summary>
private void SendString(string text)
{
try
{
byte[] buffer = Encoding.ASCII.GetBytes(text);
ClientSocket.Send(buffer, 0, buffer.Length, SocketFlags.None);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void button1_Click(object sender, EventArgs e)
{
SendRequest(txtMessage.Text);
ReceiveResponse();
UpdateControls();
}
private void Exit()
{
SendString("exit"); // Tell the server we are exiting
ClientSocket.Shutdown(SocketShutdown.Both);
ClientSocket.Close();
Environment.Exit(0);
}
public void ReceiveResponse()
{
var buffer = new byte[2048];
try
{
if (buffer.ToString().Length == 2048) return;
int received = ClientSocket.Receive(buffer, SocketFlags.None);
if (received == 0) return;
var data = new byte[received];
Array.Copy(buffer, data, received);
string text = Encoding.ASCII.GetString(data);
txtFromServer.Text += text + System.Environment.NewLine;
//MessageBox.Show(text);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return;
}
}
private void frmTCPClient_FormClosed(object sender, FormClosedEventArgs e)
{
Exit();
}
} }
Update
foreach (object obj in clientSockets)
{
string message = "meeting";
byte[] data = Encoding.ASCII.GetBytes(message);
Socket socket = (Socket)obj;
socket.Send(data);
Console.WriteLine("Meeting invite sent to " + socket.RemoteEndPoint);
}
Image
enter image description here

C# Socket Send and Receive on Same Machine

I am in the process of making a C# socket library that can be accessed in Visual FoxPro. Ideally, the library will contain two functions: ReceiveMessage and SendMessage. On each call, the function is supposed to {open connection -> read/write -> close connection}. I found most of what I am looking for at http://www.csharp-examples.net/socket-send-receive/; however, now I have to test (on the same machine) the modified code before compiling the dll.
I keep getting a "connection actively refused" error. While I have included all of the code below so you can see what it is doing, the issue is almost certainly in the main() at the bottom. It is my limited understanding that I cannot have two connections to the same port, but I am at a loss on how to fix it. Does anybody know sockets who can give me some direction on how to test these functions (I am new to sockets)?
namespace Sockets
{
class Sockets
{
private static void Receive(Socket socket, byte[] buffer, int offset, int size, int timeout)
{
int startTickCount = Environment.TickCount;
int received = 0; // how many bytes is already received
do
{
if (Environment.TickCount > startTickCount + timeout)
throw new Exception("Timeout.");
try
{
received += socket.Receive(buffer, offset + received, size - received, SocketFlags.None);
}
catch (SocketException ex)
{
if (ex.SocketErrorCode == SocketError.WouldBlock ||
ex.SocketErrorCode == SocketError.IOPending ||
ex.SocketErrorCode == SocketError.NoBufferSpaceAvailable)
{
// socket buffer is probably empty, wait and try again
Thread.Sleep(30);
}
else
throw ex; // any serious error occurr
}
} while (received < size);
}
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
private static void Send(Socket socket, byte[] buffer, int offset, int size, int timeout)
{
int startTickCount = Environment.TickCount;
int sent = 0; // how many bytes is already sent
do
{
if (Environment.TickCount > startTickCount + timeout)
throw new Exception("Timeout.");
try
{
sent += socket.Send(buffer, offset + sent, size - sent, SocketFlags.None);
}
catch (SocketException ex)
{
if (ex.SocketErrorCode == SocketError.WouldBlock ||
ex.SocketErrorCode == SocketError.IOPending ||
ex.SocketErrorCode == SocketError.NoBufferSpaceAvailable)
{
// socket buffer is probably full, wait and try again
Thread.Sleep(30);
}
else
throw ex; // any serious error occurr
}
} while (sent < size);
}
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
public static string SendMessage(string ipAddress, string port, string message)
{
Socket socket = new TcpClient().Client;
try
{
socket.Connect(ipAddress, Int32.Parse(port));
Send(socket, Encoding.UTF8.GetBytes(message), 0, message.Length, 10000);
socket.Close();
return "Success";
}
catch (Exception e)
{
socket.Close();
return e.Message;
}
}
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
public static string ReceiveMessage(string ipAddress, string port, int bufferSize = 1024)
{
Socket socket = new TcpClient().Client;
try
{
socket.Connect(ipAddress, Int32.Parse(port));
byte[] buffer = new byte[bufferSize];
Receive(socket, buffer, 0, buffer.Length, 10000);
socket.Close();
return Encoding.UTF8.GetString(buffer, 0, buffer.Length);
}
catch (Exception e)
{
socket.Close();
return e.Message;
}
}
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
// -----------------------------------------------------------------------------------------------------------------------
}
}
class Program
{
static void Main(string[] args)
{
new Thread(delegate() {var test = Sockets.Sockets.SendMessage("localhost", "60010", "abcdefg");}).Start();
new Thread(delegate() {Console.WriteLine(Sockets.Sockets.ReceiveMessage("localhost", "60010"));}).Start();
var waitForEnter = Console.ReadLine();
}
}

With a tilda (~) as the trailing character, here is the functional receive function (old code is commented):
public static string ReceiveMessage(string ipAddress, string port, int bufferSize = 1024)
{
try
{
TcpListener serverSocket = new TcpListener(new System.Net.IPAddress(IPAddress.Parse(ipAddress).GetAddressBytes()), Int32.Parse(port));
serverSocket.Start();
TcpClient clientSocket = serverSocket.AcceptTcpClient();
NetworkStream networkStream = clientSocket.GetStream();
int bytesRead;
string buffer = "";
byte[] bytesFrom = new byte[bufferSize];
while (true)
{
bytesRead = networkStream.Read(bytesFrom, 0, bytesFrom.Length);
string incoming = System.Text.Encoding.ASCII.GetString(bytesFrom, 0, bytesRead);
buffer = buffer + incoming;
while (buffer.Contains("~"))
{
string msg = buffer.Substring(0, buffer.IndexOf("~"));
// buffer = buffer.Remove(0, msg.Length + 3);
return msg;
}
}
//var socket = new TcpListener(new IPAddress(IPAddress.Parse(ipAddress).GetAddressBytes()), Int32.Parse(port));
//try
//{
//byte[] buffer = new byte[bufferSize];
// Receive(socket, buffer, 0, buffer.Length, 10000);
// socket.Close();
// return Encoding.UTF8.GetString(buffer, 0, buffer.Length);
//}
//catch (Exception e)
//{
// socket.Close();
// return e.Message;
//}
}
catch (Exception e)
{
return e.Message;
}
}

create c# asynchronous socket client in multithreaded environment

I am trying to create asynchronous socket client in multithreaded environment but it is not working correctly.
As below sample code,
If i create new AsyncSocketClient and call StartClent from multi-threaded environment it will process only one or two for rest, it is not processing.(I am creating new AsyncSocketClient with every new request)
Is it because of static variables,
class AsyncSocketClient
{
private static AutoResetEvent sendDone =
new AutoResetEvent(false);
private static AutoResetEvent receiveDone =
new AutoResetEvent(false);
private static ManualResetEvent connectDone =
new ManualResetEvent(false);
static private String response = "";
public void StartClent()
{
Socket workSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// clientSock.ReceiveTimeout = 1;
try
{
workSocket.BeginConnect(new IPEndPoint(IPAddress.Loopback, 8080), new AsyncCallback(ConnectCallBack), workSocket);
connectDone.WaitOne();
Send(s.workSocket, "<EOF>");
sendDone.WaitOne();
Receive(workSocket);
receiveDone.WaitOne();
}
catch(Exception ex)
{
}
}
private void ConnectCallBack(IAsyncResult ar)
{
Socket workSocket = (Socket)ar.AsyncState;
workSocket.EndConnect(ar);
connectDone.Set();
}
private void Receive(Socket client)
{
StateObject state = new StateObject();
state.workSocket = client;
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallBack), state);
}
private void ReceiveCallBack(IAsyncResult ar)
{
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
int byteReceived= client.EndReceive(ar);
if (byteReceived > 0)
{
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, state.buffer.Length));
Array.Clear(state.buffer, 0, state.buffer.Length);
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallBack), state);
}
else
{
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
receiveDone.Set();
}
}
private void Send(Socket client,string data)
{
byte[] sendBufer = Encoding.ASCII.GetBytes(data);
client.BeginSend(sendBufer, 0, sendBufer.Length, 0, new AsyncCallback(BeginSendCallBack), client);
}
private void BeginSendCallBack(IAsyncResult ar)
{
Socket client = (Socket)ar.AsyncState;
int byteSent= client.EndSend(ar);
Console.WriteLine("Sent {0} bytes to server.", byteSent);
sendDone.Set();
}
}
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 30;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

Here is an example of a non blocking client and server with a simple echo implemented. There is no error checking and nothing is closed correctly which should be done. The server has some synchronous code just to make it easier to follow.
Client
public class AsyncClient
{
private const int Port = 9999;
private readonly string _clientId;
private readonly Random _random;
public AsyncClient(int clientId)
{
_clientId = string.Format("Client Id: {0}", clientId);
_random = new Random(clientId);
}
public void StartClient()
{
try
{
var workSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
var state = new ClientState { WorkSocket = workSocket };
workSocket.BeginConnect(new IPEndPoint(IPAddress.Loopback, Port), ConnectCallBack, state);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
private void ConnectCallBack(IAsyncResult ar)
{
var state = (ClientState) ar.AsyncState;
state.WorkSocket.EndConnect(ar);
Send(state);
}
private void Receive(ClientState clientState)
{
clientState.WorkSocket.BeginReceive(clientState.Buffer, 0, ClientState.BufferSize, 0, ReceiveCallBack, clientState);
}
private void ReceiveCallBack(IAsyncResult ar)
{
var state = (ClientState) ar.AsyncState;
Socket client = state.WorkSocket;
int byteReceived= client.EndReceive(ar);
if (byteReceived > 0)
{
var receivedString = Encoding.UTF8.GetString(state.Buffer, 0, byteReceived);
Console.WriteLine("From Server: " + receivedString);
Array.Clear(state.Buffer, 0, state.Buffer.Length);
state.Count++;
Thread.Sleep(1000 + _random.Next(2000));
Send(state);
}
}
private void Send(ClientState clientState)
{
Console.WriteLine("Sending " + _clientId);
byte[] buffer = Encoding.UTF8.GetBytes(string.Format("Send from Thread {0} Client id {1} Count {2}", Thread.CurrentThread.ManagedThreadId, _clientId,clientState.Count));
clientState.WorkSocket.BeginSend(buffer, 0, buffer.Length, 0, BeginSendCallBack, clientState);
}
private void BeginSendCallBack(IAsyncResult ar)
{
var state = (ClientState) ar.AsyncState;
int byteSent= state.WorkSocket.EndSend(ar);
Console.WriteLine("Sent {0} bytes to server.", byteSent);
Receive(state);
}
}
public class ClientState
{
// Client socket.
public Socket WorkSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] Buffer = new byte[BufferSize];
public int Count = 0;
}
Server
public class AsyncServer
{
private const int Port = 9999;
public void StartServer()
{
var thread = new Thread(Run) {IsBackground = true};
thread.Start();
}
private void Run()
{
Console.WriteLine("Running");
var tcpListener = new TcpListener(IPAddress.Loopback, Port);
tcpListener.Start();
while (true)
{
Console.WriteLine("Before Accept");
var state = new ServerState {WorkSocket = tcpListener.AcceptSocket()};
Console.WriteLine("Before Recieve");
Receive(state);
}
}
private void Receive(ServerState state)
{
state.WorkSocket.BeginReceive(state.Buffer, 0, ServerState.BufferSize, 0, ReceiveCallBack, state);
}
private void ReceiveCallBack(IAsyncResult ar)
{
Console.WriteLine("ReceiveCallBack");
var state = (ServerState) ar.AsyncState;
try
{
int byteReceived= state.WorkSocket.EndReceive(ar);
if (byteReceived > 0)
{
var receivedString = Encoding.UTF8.GetString(state.Buffer, 0, byteReceived);
Console.WriteLine("Received: " + receivedString);
var bytesToSend = Encoding.UTF8.GetBytes("Server Got --> " + receivedString);
Array.Copy(bytesToSend, state.Buffer, bytesToSend.Length);
state.WorkSocket.Send(state.Buffer, 0, bytesToSend.Length, SocketFlags.None);
Array.Clear(state.Buffer, 0, state.Buffer.Length);
Receive(state);
}
}
catch (Exception e)
{
Console.WriteLine(e);
}
}
private class ServerState
{
public const int BufferSize = 1024;
public readonly byte[] Buffer = new byte[1024];
public Socket WorkSocket;
}
I have run this using a console you can either have two applications or just launch the client and server separately.
static void Main(string[] args)
{
if (args.Length != 0)
{
var server = new AsyncServer();
server.StartServer();
}
else
{
for(int i = 0; i < 10; i++)
{
var client = new AsyncClient(i);
client.StartClient();
}
}
Console.WriteLine("Press a key to exit");
Console.ReadKey();
}

c# SocketAsyncEventArgs blocking code inside ReceiveAsync handler

I have the the following two scenarios that I am testing and one works but the other does not.
I have socket server and socket client application running on two different machines
both the scenarios are using the socketasynceventargs
Scenario 1 (Works)
create 40k socket clients in a loop, wait for all connections to be established and then all clients send messages to the server at the same time and receive response from the server 10 times(i.e. send/receive happens 10 times).
Scenario 2 (Does not work. I get a lot of connection refusal errors)
create 40k socket clients in a loop and send/receive the same 10 messages to the server as soon as each client is connected instead of waiting for the 40k connections to be established.
I cant figure out why my second scenario would fail. i understand that in scenario 1 the server is not doing much until all the 40k connections are made. but it is able to communicate with all the clients at the same time. any ideas??
Thank you for you patience.
here is the socket server code
public class SocketServer
{
private static System.Timers.Timer MonitorTimer = new System.Timers.Timer();
public static SocketServerMonitor socket_monitor = new SocketServerMonitor();
private int m_numConnections;
private int m_receiveBufferSize;
public static BufferManager m_bufferManager;
Socket listenSocket;
public static SocketAsyncEventArgsPool m_readWritePool;
public static int m_numConnectedSockets;
private int cnt = 0;
public static int Closecalled=0;
public SocketServer(int numConnections, int receiveBufferSize)
{
m_numConnectedSockets = 0;
m_numConnections = numConnections;
m_receiveBufferSize = receiveBufferSize;
m_bufferManager = new BufferManager(receiveBufferSize * numConnections ,
receiveBufferSize);
m_readWritePool = new SocketAsyncEventArgsPool(numConnections);
}
public void Init()
{
MonitorTimer.Interval = 30000;
MonitorTimer.Start();
MonitorTimer.Elapsed += new System.Timers.ElapsedEventHandler(socket_monitor.Log);
m_bufferManager.InitBuffer();
SocketAsyncEventArgs readWriteEventArg;
for (int i = 0; i < m_numConnections; i++)
{
readWriteEventArg = new SocketAsyncEventArgs();
m_readWritePool.Push(readWriteEventArg);
}
}
public void Start(IPEndPoint localEndPoint)
{
listenSocket = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
listenSocket.Bind(localEndPoint);
listenSocket.Listen(1000);
StartAccept(null);
}
public void Stop()
{
if (listenSocket == null)
return;
listenSocket.Close();
listenSocket = null;
Thread.Sleep(15000);
}
private void StartAccept(SocketAsyncEventArgs acceptEventArg)
{
if (acceptEventArg == null)
{
acceptEventArg = new SocketAsyncEventArgs();
acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(AcceptEventArg_Completed);
}
else
{
// socket must be cleared since the context object is being reused
acceptEventArg.AcceptSocket = null;
}
try
{
bool willRaiseEvent = listenSocket.AcceptAsync(acceptEventArg);
if (!willRaiseEvent)
{
ProcessAccept(acceptEventArg);
}
}
catch (Exception e)
{
}
}
void AcceptEventArg_Completed(object sender, SocketAsyncEventArgs e)
{
ProcessAccept(e);
}
private void ProcessAccept(SocketAsyncEventArgs e)
{
Interlocked.Increment(ref m_numConnectedSockets);
socket_monitor.IncSocketsConnected();
SocketAsyncEventArgs readEventArgs = m_readWritePool.Pop();
m_bufferManager.SetBuffer(readEventArgs);
readEventArgs.UserToken = new AsyncUserToken { id = cnt++, StarTime = DateTime.Now };
readEventArgs.AcceptSocket = e.AcceptSocket;
SocketHandler handler=new SocketHandler(readEventArgs);
StartAccept(e);
}
}
class SocketHandler
{
private SocketAsyncEventArgs _socketEventArgs;
public SocketHandler(SocketAsyncEventArgs socketAsyncEventArgs)
{
_socketEventArgs = socketAsyncEventArgs;
_socketEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>(IO_Completed);
StartReceive(_socketEventArgs);
}
private void StartReceive(SocketAsyncEventArgs receiveSendEventArgs)
{
bool willRaiseEvent = receiveSendEventArgs.AcceptSocket.ReceiveAsync(receiveSendEventArgs);
if (!willRaiseEvent)
{
ProcessReceive(receiveSendEventArgs);
}
}
private void ProcessReceive(SocketAsyncEventArgs e)
{
// check if the remote host closed the connection
AsyncUserToken token = (AsyncUserToken)e.UserToken;
//token.StarTime = DateTime.Now;
if (e.BytesTransferred > 0 && e.SocketError == SocketError.Success)
{
// process the data here
//reply to client
byte[] AckData1 = BitConverter.GetBytes(1);
SendData(AckData1, 0, AckData1.Length, e);
StartReceive(e);
}
else
{
CloseClientSocket(e);
}
}
private void IO_Completed(object sender, SocketAsyncEventArgs e)
{
// determine which type of operation just completed and call the associated handler
switch (e.LastOperation)
{
case SocketAsyncOperation.Receive:
ProcessReceive(e);
break;
case SocketAsyncOperation.Send:
ProcessSend(e);
break;
default:
throw new ArgumentException("The last operation completed on the socket was not a receive or send");
}
}
private void CloseClientSocket(SocketAsyncEventArgs e)
{
AsyncUserToken token = e.UserToken as AsyncUserToken;
// close the socket associated with the client
try
{
e.AcceptSocket.Shutdown(SocketShutdown.Send);
}
catch (Exception ex)
{
}
e.AcceptSocket.Close();
Interlocked.Decrement(ref SocketServer.m_numConnectedSockets);
SocketServer.socket_monitor.DecSocketsConnected();
SocketServer.m_bufferManager.FreeBuffer(e);
e.Completed -= new EventHandler<SocketAsyncEventArgs>(IO_Completed);
SocketServer.m_readWritePool.Push(e);
}
public void SendData(Byte[] data, Int32 offset, Int32 count, SocketAsyncEventArgs args)
{
try
{
Socket socket = args.AcceptSocket;
if (socket.Connected)
{
var i = socket.Send(data, offset, count, SocketFlags.None);
}
}
catch (Exception Ex)
{
}
}
}
here is the client code that throws the error in the connectcallback method
// State object for receiving data from remote device.
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 256;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
public int count = 0;
}
public class AsynchronousClient
{
// The port number for the remote device.
private const int port = 11000;
private static int closecalled = 0;
private static bool wait = true;
// 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);
// The response from the remote device.
private static String response = String.Empty;
private static void StartClient(Socket client, IPEndPoint remoteEP)
{
// Connect to a remote device.
try
{
// Connect to the remote endpoint.
client.BeginConnect(remoteEP,
new AsyncCallback(ConnectCallback), new StateObject { workSocket = client });
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
StateObject state = (StateObject)ar.AsyncState;
var client = state.workSocket;
// Complete the connection.
client.EndConnect(ar);
var data = "AA5500C08308353816050322462F01020102191552E7D3FA52E7D3FB1FF85BF1FE9F201000004AB80000000500060800001EFFB72F0D00002973620000800000FFFFFFFF00009D6D00003278002EE16D0000018500000000000000000000003A0000000100000000828C80661FF8B436FE9EA9FC000000120000000700000000000000000000000400000000000000000000000000000000000000000000281E0000327800000000000000000000000000AF967D00000AEA000000000000000000000000";
Send(state, data);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void Receive(StateObject state)
{
try
{
Socket client = state.workSocket;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
//if (wait)
//{
// connectDone.WaitOne();
//}
if (bytesRead > 0)
{
state.count = state.count + 1;
byte[] b = new byte[bytesRead];
Array.Copy(state.buffer, b, 1);
if (b[0] == 1)
{
if (state.count < 10)
{
var data = "AA5500C08308353816050322462F01020102191552E7D3FA52E7D3FB1FF85BF1FE9F201000004AB80000000500060800001EFFB72F0D00002973620000800000FFFFFFFF00009D6D00003278002EE16D0000018500000000000000000000003A0000000100000000828C80661FF8B436FE9EA9FC000000120000000700000000000000000000000400000000000000000000000000000000000000000000281E0000327800000000000000000000000000AF967D00000AEA000000000000000000000000";
Send(state, data);
}
else
{
Interlocked.Increment(ref closecalled);
Console.WriteLine("closecalled:-" + closecalled + " at " + DateTime.Now);
client.Close();
}
}
else
{
// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
}
else
{
client.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void Send(StateObject state, String data)
{
try
{
Socket client = state.workSocket;
var hexlen = data.Length;
byte[] byteData = new byte[hexlen / 2];
int[] hexarray = new int[hexlen / 2];
int i = 0;
int k = 0;
//create the byte array
while (i < data.Length / 2)
{
string first = data[i].ToString();
i++;
string second = data[i].ToString();
string x = first + second;
byteData[k] = (byte)Convert.ToInt32(x, 16);
i++;
k++;
}
// Begin sending the data to the remote device.
client.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Complete sending the data to the remote device.
int bytesSent = client.EndSend(ar);
Receive(state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public static int Main(String[] args)
{
Start();
Console.ReadLine();
return 0;
}
private static void Start()
{
IPAddress ipaddress = IPAddress.Parse("10.20.2.152");
IPEndPoint remoteEP = new IPEndPoint(ipaddress, port);
for (int i = 0; i < 40000; i++)
{
Thread.Sleep(1);
// Create a TCP/IP socket.
try
{
Socket client = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
StartClient(client, remoteEP);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
if (i == 39999)
{
Console.WriteLine("made all conns at " + DateTime.Now);
}
}
}
}

I would use a linear queue to accept incoming connections. Something like this:
public async Task Accept40KClients()
{
for (int i = 0; i < 40000; i++)
{
// Await this here -------v
bool willRaiseEvent = await listenSocket.AcceptAsync(acceptEventArg);
if (!willRaiseEvent)
{
ProcessAccept(acceptEventArg);
}
}
}
If that's not fast enough, maybe you can do 10 waits at a time, but I think this is good enough... I might be wrong on this though.