#c# #.net #sockets #callback #send
Вопрос:
Я попытался построить простое взаимодействие с клиент — сервером. Клиент подключается к серверу и отправляет сообщение. Сервер принимает клиента и считывает сообщение. Теперь сервер должен ответить, но это не работает 🙁
Только если я отключу направление отправки на стороне сервера, клиент получит ответ сервера. Но я не хочу ничего выключать, потому что я хочу отправлять и получать больше сообщений.
Я думаю, что проблема на стороне сервера в методе Send() или SendCallback()
Кто-нибудь может мне помочь?
(Код выполним.)
Сервер:
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
namespace WebSocket
{
// State object for reading client data asynchronously
public class StateObject
{
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
// Client socket.
public Socket workSocket = null;
}
public class AsynchronousSocketListener
{
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);
public AsynchronousSocketListener()
{
}
public static void StartListening()
{
// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
// IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = IPAddress.Parse("127.0.0.1"); //ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
Console.WriteLine("[Server] Waiting for a connection...");
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception e)
{
Console.WriteLine($"[Server] {e.ToString()}");
}
Console.WriteLine("n[Server] Press ENTER to continue...");
Console.Read();
}
public static void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
}
public static void ReadCallback(IAsyncResult ar)
{
String content = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// Check for end-of-file tag. If it is not there, read
// more data.
content = state.sb.ToString();
if (content.IndexOf("<EOF>") > -1)
{
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("[Server] Read {0} bytes from socket. Data: {1}", content.Length, content);
// Echo the data back to the client.
Send(handler, content);
}
else
{
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;
handler.NoDelay = true;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("[Server] Sent {0} bytes to client.", bytesSent);
handler.Send(new byte[0xFF]);
// Here is the Problem. It only works if I uncomment the following line. But then I receive an Error when I try to Send again.
// handler.Shutdown(SocketShutdown.Send);
// handler.Close();
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
}
catch (Exception e)
{
Console.WriteLine($"[Server] {e.ToString()}");
}
Console.WriteLine("[Server] End of SendCallback");
}
public static int Main(String[] args)
{
Thread client = new Thread(AsynchronousClient.StartClient);
client.Start();
StartListening();
return 0;
}
}
}
Клиент:
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;
namespace WebSocket
{
public class AsynchronousClient
{
// The port number for the remote device.
private const int port = 11000;
// 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;
public static void StartClient()
{
Console.WriteLine("[Client] Start...");
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// The name of the
// remote device is "host.contoso.com".
//IPHostEntry ipHostInfo = Dns.GetHostEntry("host.contoso.com");
IPAddress ipAddress = IPAddress.Parse("127.0.0.1"); //ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
Socket client = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
for (int i = 0; i < 10; i )
{
Console.WriteLine("n[Client] ----------- New message -----------");
// Send test data to the remote device.
Send(client, $"This is a test<EOF>");
sendDone.WaitOne();
// Receive the response from the remote device.
Receive(client);
receiveDone.WaitOne();
// Write the response to the console.
Console.WriteLine("[Client] Response received: {0}", response);
Thread.Sleep(5000);
}
// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();
}
catch (Exception e)
{
Console.WriteLine($"[Client] {e.ToString()}");
}
}
private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete the connection.
client.EndConnect(ar);
Console.WriteLine("[Client] Socket connected to {0}", client.RemoteEndPoint.ToString());
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
Console.WriteLine($"[Client] {e.ToString()}");
}
}
private static void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine($"[Client] {e.ToString()}");
}
}
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);
}
else
{
// All the data has arrived; put it in response.
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine($"[Client] {e.ToString()}");
}
}
private static void Send(Socket client, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
client.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), client);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = client.EndSend(ar);
Console.WriteLine("[Client] Sent {0} bytes to server.", bytesSent);
// Signal that all bytes have been sent.
sendDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
}
Я остро использую .NET 5.0