/// <summary>
/// Begins listening for requests.
/// </summary>
/// <param name="cancellationToken">A token to observe for cancellation.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous listening operation.</returns>
public Task StartAsync(CancellationToken cancellationToken)
{
Task.Run(async() =>
{
try
{
this.tcpListener.Start();
// Stop() makes AcceptSocketAsync() throw an ObjectDisposedException.
// This means that when the token is cancelled, the callback action here will be to Stop() the listener,
// which in turn throws the exception and it gets caught below, exiting gracefully.
cancellationToken.Register(() => this.tcpListener.Stop());
while (!cancellationToken.IsCancellationRequested)
{
try
{
var socket = await this.tcpListener.AcceptSocketAsync().ConfigureAwait(false);
ISocketConnection socketConnection = this.socketConnectionFactory.Create(socket);
if (this.dosDefender?.IsBlocked(socketConnection.SocketIp) ?? false)
{
// TODO: evaluate if it is worth just leaving the connection open but ignore it, so that they think they are successfully DoSing...
// But we would need to think if it is a connection drain attack then...
socketConnection.Close();
continue;
}
this.NewConnection?.Invoke(socketConnection);
socketConnection.Closed += this.OnConnectionClose;
socketConnection.PacketProcessed += this.AfterConnectionMessageProcessed;
this.dosDefender?.LogConnectionAttempt(socketConnection.SocketIp);
socketConnection.Read();
}
catch (ObjectDisposedException)
{
// This is normal when the listerner is stopped because of token cancellation.
break;
}
catch (Exception socEx)
{
this.Logger.Error(socEx.ToString());
}
}
}
catch (SocketException socEx)
{
this.Logger.Error(socEx.ToString());
}
});
// return this to allow other IHostedService-s to start.
return(Task.CompletedTask);
}
public void Close()
{
_socket?.Close();
_socket = null;
_mouseSocket?.Close();
_mouseSocket = null;
}
public void Dispose()
{
_isDisposed = true;
_keepAliveTimer.Enabled = false;
_keepAliveTimer.Stop();
_packetProtocol.MessageArrived = null;
_packetProtocol.KeepAliveArrived = null;
_socket.Disconnect(false);
_socket.Dispose();
_socket.Close();
}