private static async Task ListenerProcessingLoopAsync()
{
var cancellationToken = ListenerLoopTokenSource.Token;
try
{
while (!cancellationToken.IsCancellationRequested)
{
HttpListenerContext context = await Listener.GetContextAsync();
if (ServerIsRunning)
{
if (context.Request.IsWebSocketRequest)
{
// HTTP is only the initial connection; upgrade to a client-specific websocket
HttpListenerWebSocketContext wsContext = null;
try
{
wsContext = await context.AcceptWebSocketAsync(subProtocol : null);
int socketId = Interlocked.Increment(ref SocketCounter);
var client = new ConnectedClient(socketId, wsContext.WebSocket);
Clients.TryAdd(socketId, client);
Console.WriteLine($"Socket {socketId}: New connection.");
_ = Task.Run(() => SocketProcessingLoopAsync(client).ConfigureAwait(false));
}
catch (Exception)
{
// server error if upgrade from HTTP to WebSocket fails
context.Response.StatusCode = 500;
context.Response.StatusDescription = "WebSocket upgrade failed";
context.Response.Close();
return;
}
}
else
{
if (context.Request.AcceptTypes.Contains("text/html"))
{
Console.WriteLine("Sending HTML to client.");
ReadOnlyMemory <byte> HtmlPage = new ReadOnlyMemory <byte>(Encoding.UTF8.GetBytes(SimpleHtmlClient.HTML));
context.Response.ContentType = "text/html; charset=utf-8";
context.Response.StatusCode = 200;
context.Response.StatusDescription = "OK";
context.Response.ContentLength64 = HtmlPage.Length;
await context.Response.OutputStream.WriteAsync(HtmlPage, CancellationToken.None);
await context.Response.OutputStream.FlushAsync(CancellationToken.None);
}
else
{
context.Response.StatusCode = 400;
}
context.Response.Close();
}
}
else
{
// HTTP 409 Conflict (with server's current state)
context.Response.StatusCode = 409;
context.Response.StatusDescription = "Server is shutting down";
context.Response.Close();
return;
}
}
}
catch (HttpListenerException ex) when(ServerIsRunning)
{
Program.ReportException(ex);
}
}
private static async Task SocketProcessingLoopAsync(ConnectedClient client)
{
_ = Task.Run(() => client.LoopAsync().ConfigureAwait(false));
var socket = client.Socket;
var loopToken = SocketLoopTokenSource.Token;
var broadcastTokenSource = client.LoopTokenSource; // armazenar uma cópia para uso no bloco finalmente
try
{
var buffer = WebSocket.CreateServerBuffer(4096);
while (socket.State != WebSocketState.Closed && socket.State != WebSocketState.Aborted && !loopToken.IsCancellationRequested)
{
var receiveResult = await client.Socket.ReceiveAsync(buffer, loopToken);
// se o token for cancelado enquanto o ReceiveAsync estiver bloqueando, o estado do soquete mudará para abortado e não poderá ser usado
if (!loopToken.IsCancellationRequested)
{
// o cliente está nos notificando que a conexão será fechada; enviar confirmação
if (client.Socket.State == WebSocketState.CloseReceived && receiveResult.MessageType == WebSocketMessageType.Close)
{
Console.WriteLine($"Socket {client.SocketId}: Confirmando Fechar quadro recebido do cliente ");
broadcastTokenSource.Cancel();
await socket.CloseOutputAsync(WebSocketCloseStatus.NormalClosure, "Confirmar quadro fechado", CancellationToken.None);
// o estado do soquete muda para fechado neste momento
}
// echo text ou dados binários para a fila de transmissão
if (client.Socket.State == WebSocketState.Open)
{
Console.WriteLine($"Socket {client.SocketId}: Received {receiveResult.MessageType} frame ({receiveResult.Count} bytes).");
Console.WriteLine($"Socket {client.SocketId}: Echoing data to queue.");
string message = Encoding.UTF8.GetString(buffer.Array, 0, receiveResult.Count);
client.BroadcastQueue.Add(message);
}
}
}
}
catch (OperationCanceledException)
{
// normal mediante cancelamento de tarefa / token, desconsidera
}
catch (Exception ex)
{
Console.WriteLine($"Socket {client.SocketId}:");
Program.ReportException(ex);
}
finally
{
broadcastTokenSource.Cancel();
Console.WriteLine($"Socket {client.SocketId}: Loop de processamento finalizado no estado {socket.State}");
// não deixe o Socket em nenhum estado potencialmente conectado
if (client.Socket.State != WebSocketState.Closed)
{
client.Socket.Abort();
}
// nesse ponto, o Socket é fechado ou abortado, o objeto ConnectedClient é inútil
if (Clients.TryRemove(client.SocketId, out _))
{
socket.Dispose();
}
}
}
