我正在尝试在 C# 中实现一个基于 tcp 的小型应用程序。我是 TCP 编程的新手。
该应用程序非常简单。这是一个客户端/服务器方案，最多支持 2 个客户端。一个客户端将是“外部”IP，另一个将是主机本身。
每次客户端连接到服务器时，它都会开始从/向服务器接收和发送数据包。
我已经建立了一个小型控制台应用程序，它实现了 TCP 服务器端代码和 TCP 客户端代码。
服务器使用绑定到特定端口的侦听器并等待客户端连接。连接客户端后，它会生成一个新线程来处理与客户端的通信。
客户端只需连接到服务器，一旦连接建立，它就会开始接收和发送数据包。
正如我之前所说的“主机也是它自己的客户”，但这会导致一个问题。如果客户端向服务器发送一个数据包，服务器和客户端都声称收到了一个数据包。这是正常的？我错过了什么吗？
更新 2（修复问题）
我想我找到了问题所在。客户端完成发送操作后，我需要“重置”缓冲区
case SocketAsyncOperation.Send:
// Put in listen mode
// Buffer reset AFTER send and BEFORE receive
_receiver.SetBuffer(new byte[4096], 0, 4096);
_client.ReceiveAsync(_receiver);
break;
更新 1（添加代码）
服务器
public void Host()
{
_listener = new TcpListener(new IPEndPoint(IPAddress.Any, this.ConnectionPort));
_listener.Start();
this.IsListening = true;
ThreadPool.QueueUserWorkItem((state) =>
{
while (true)
{
// Blocks until a client connections occours
// If continue with no client then stop listening
try
{
TcpClient client = _listener.AcceptTcpClient();
// Add client to peer list
long assignedID = DateTime.UtcNow.Ticks;
_clients.Add(assignedID, client);
HandleClient(assignedID);
if (this.ConnectedClients == this.MaxClients)
{
_listener.Stop();
this.IsListening = false;
break;
}
}
catch
{
// Server has stop listening
_stopListen.Set();
break;
}
}
});
}
private void HandleClient(long assignedID)
{
ThreadPool.QueueUserWorkItem((state) =>
{
long clientID = (long)state;
TcpClient client = _clients[clientID];
try
{
byte[] message = new byte[4096];
byte[] buffer = new byte[4096];
int readed = 0;
int index = 0;
NetworkStream clientStream = client.GetStream();
while (true)
{
readed = clientStream.Read(message, 0, message.Length);
if (readed == 0)
{
// Client disconnected, thorw exception
throw new SocketException();
}
Array.Copy(message, 0, buffer, index, readed);
index += readed;
if (readed == 4096
&& !_packetHub.IsValidBufferData(buffer))
{
Array.Clear(buffer, 0, buffer.Length);
readed = 0;
index = 0;
continue;
}
if (_packetHub.IsValidBufferData(buffer))
{
NetPacket receivedPacket = _packetHub.DeserializePacket(buffer);
NetPacket answerPacket = null;
// Assign sender ID in case of unknown sender ID
if (receivedPacket.SenderID == NetPacket.UnknownID)
receivedPacket.SenderID = clientID;
// Handle received packet and forward answer packet
// to the client or to all other connected peers
answerPacket = HandlePacket(receivedPacket);
if (answerPacket != null)
{
if (answerPacket.RecipientID == clientID)
{
// Send answer packet to the client
SendPacket(client, answerPacket);
}
else
{
// Broadcast packet to all clients
foreach (TcpClient peer in _clients.Values)
SendPacket(peer, answerPacket);
}
}
// Reset receive packet buffer
Array.Clear(buffer, 0, buffer.Length);
readed = 0;
index = 0;
}
}
}
catch
{
System.Diagnostics.Debug.WriteLine("Network error occours!");
}
finally
{
// Close client connection
client.Close();
// Remove the client from the list
_clients.Remove(clientID);
// Raise client disconnected event
OnClientDisconnected();
}
}, assignedID);
}
客户
public void Connect()
{
if (this.ConnectionAddress == null)
throw new InvalidOperationException("Unable to connect. No server IP specified.");
_receiver = new SocketAsyncEventArgs();
_receiver.RemoteEndPoint = new IPEndPoint(this.ConnectionAddress, this.ConnectionPort);
_receiver.SetBuffer(new byte[4096], 0, 4096);
_receiver.Completed += new EventHandler<SocketAsyncEventArgs>(Socket_OperationComplete);
_client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_client.ConnectAsync(_receiver);
}
private void Socket_OperationComplete(object sender, SocketAsyncEventArgs e)
{
if (e.SocketError == SocketError.Success)
{
switch (e.LastOperation)
{
case SocketAsyncOperation.Connect:
_readyToSend = true;
this.IsConnected = true;
// Once connection is estabilished, send a join packet to
// retrive server side assigned informations
JoinPacket joinPacket = (JoinPacket)NetPacket.CreatePacket(this.ClientID, NetPacket.ToHost, NetPacket.JoinPacket);
joinPacket.ClientName = this.ClientName;
joinPacket.ClientAddress = this.LocalAddress.ToString();
SendPacket(joinPacket);
break;
case SocketAsyncOperation.Receive:
_readyToSend = true;
byte[] buffer = _receiver.Buffer;
System.Diagnostics.Debug.WriteLine("Client received packet (" + _packetHub.GetBufferDataType(buffer) + ") with length of: " + buffer.Length);
if (_packetHub.IsValidBufferData(buffer))
{
NetPacket receivedPacket = _packetHub.DeserializePacket(buffer);
NetPacket answerPacket = null;
// Handle received packet and forward answer packet
// to the server
answerPacket = HandlePacket(receivedPacket);
if (answerPacket != null)
SendPacket(answerPacket);
}
else
{
_client.ReceiveAsync(_receiver);
}
break;
case SocketAsyncOperation.Send:
// Put in listen mode
_client.ReceiveAsync(_receiver);
break;
}
}
else
{
OnClientDisconnected();
System.Diagnostics.Debug.WriteLine(String.Format("Network error: {0}", e.SocketError.ToString()));
}
}