public async Task ExecuteAsync(HttpContext context, HttpConnectionOptions options, ConnectionDelegate connectionDelegate)
{
// Create the log scope and attempt to pass the Connection ID to it so as many logs as possible contain
// the Connection ID metadata. If this is the negotiate request then the Connection ID for the scope will
// be set a little later.
var logScope = new ConnectionLogScope(GetConnectionId(context));
using (_logger.BeginScope(logScope))
{
if (!await AuthorizeHelper.AuthorizeAsync(context, options.AuthorizationData))
{
return;
}
if (HttpMethods.IsPost(context.Request.Method))
{
// POST /{path}
await ProcessSend(context, options);
}
else if (HttpMethods.IsGet(context.Request.Method))
{
// GET /{path}
await ExecuteAsync(context, connectionDelegate, options, logScope);
}
else
{
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status405MethodNotAllowed;
}
}
}
private HttpConnectionContext CreateConnection(HttpConnectionOptions options)
{
var transportPipeOptions = new PipeOptions(pauseWriterThreshold: options.TransportMaxBufferSize, resumeWriterThreshold: options.TransportMaxBufferSize / 2, readerScheduler: PipeScheduler.ThreadPool, useSynchronizationContext: false);
var appPipeOptions = new PipeOptions(pauseWriterThreshold: options.ApplicationMaxBufferSize, resumeWriterThreshold: options.ApplicationMaxBufferSize / 2, readerScheduler: PipeScheduler.ThreadPool, useSynchronizationContext: false);
return(_manager.CreateConnection(transportPipeOptions, appPipeOptions));
}
private async Task ProcessNegotiate(HttpContext context, HttpConnectionOptions options, ConnectionLogScope logScope)
{
context.Response.ContentType = "application/json";
// Establish the connection
var connection = CreateConnection(options);
// Set the Connection ID on the logging scope so that logs from now on will have the
// Connection ID metadata set.
logScope.ConnectionId = connection.ConnectionId;
// Don't use thread static instance here because writer is used with async
var writer = new MemoryBufferWriter();
try
{
// Get the bytes for the connection id
WriteNegotiatePayload(writer, connection.ConnectionId, context, options);
Log.NegotiationRequest(_logger);
// Write it out to the response with the right content length
context.Response.ContentLength = writer.Length;
await writer.CopyToAsync(context.Response.Body);
}
finally
{
writer.Reset();
}
}
private async Task ProcessSend(HttpContext context, HttpConnectionOptions options)
{
var connection = await GetConnectionAsync(context, options);
if (connection == null)
{
// No such connection, GetConnection already set the response status code
return;
}
context.Response.ContentType = "text/plain";
var transport = (TransportType?)connection.Items[ConnectionMetadataNames.Transport];
if (transport == TransportType.WebSockets)
{
Log.PostNotAllowedForWebSockets(_logger);
context.Response.StatusCode = StatusCodes.Status405MethodNotAllowed;
await context.Response.WriteAsync("POST requests are not allowed for WebSocket connections.");
return;
}
var pipeWriterStream = new PipeWriterStream(connection.Application.Output);
await context.Request.Body.CopyToAsync(pipeWriterStream);
Log.ReceivedBytes(_logger, pipeWriterStream.Length);
}
public void MapConnections(PathString path, HttpConnectionOptions options, Action <IConnectionBuilder> configure)
{
var connectionBuilder = new ConnectionBuilder(_routes.ServiceProvider);
configure(connectionBuilder);
var socket = connectionBuilder.Build();
_routes.MapRoute(path, c => _dispatcher.ExecuteAsync(c, options, socket));
_routes.MapRoute(path + "/negotiate", c => _dispatcher.ExecuteNegotiateAsync(c, options));
}
private void EnsureConnectionStateInternal(HttpConnectionContext connection, HttpConnectionOptions options)
{
// If the connection doesn't have a pipe yet then create one, we lazily create the pipe to save on allocations until the client actually connects
if (connection.Transport == null)
{
var transportPipeOptions = new PipeOptions(pauseWriterThreshold: options.TransportMaxBufferSize, resumeWriterThreshold: options.TransportMaxBufferSize / 2, readerScheduler: PipeScheduler.ThreadPool, useSynchronizationContext: false);
var appPipeOptions = new PipeOptions(pauseWriterThreshold: options.ApplicationMaxBufferSize, resumeWriterThreshold: options.ApplicationMaxBufferSize / 2, readerScheduler: PipeScheduler.ThreadPool, useSynchronizationContext: false);
var pair = DuplexPipe.CreateConnectionPair(transportPipeOptions, appPipeOptions);
connection.Transport = pair.Application;
connection.Application = pair.Transport;
}
}
private async Task ProcessSend(HttpContext context, HttpConnectionOptions options)
{
var connection = await GetConnectionAsync(context, options);
if (connection == null)
{
// No such connection, GetConnection already set the response status code
return;
}
context.Response.ContentType = "text/plain";
if (connection.TransportType == HttpTransportType.WebSockets)
{
Log.PostNotAllowedForWebSockets(_logger);
context.Response.StatusCode = StatusCodes.Status405MethodNotAllowed;
await context.Response.WriteAsync("POST requests are not allowed for WebSocket connections.");
return;
}
const int bufferSize = 4096;
// REVIEW: Consider spliting the connection lock into a read lock and a write lock
// Need to think about HttpConnectionContext.DisposeAsync and whether one or both locks would be needed
await connection.Lock.WaitAsync();
try
{
if (connection.Status == HttpConnectionContext.ConnectionStatus.Disposed)
{
Log.ConnectionDisposed(_logger, connection.ConnectionId);
// The connection was disposed
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
await context.Request.Body.CopyToAsync(connection.ApplicationStream, bufferSize);
Log.ReceivedBytes(_logger, connection.ApplicationStream.Length);
// Clear the amount of read bytes so logging is accurate
connection.ApplicationStream.Reset();
}
finally
{
connection.Lock.Release();
}
}
public void MapConnectionHandler <TConnectionHandler>(PathString path, Action <HttpConnectionOptions> configureOptions) where TConnectionHandler : ConnectionHandler
{
var authorizeAttributes = typeof(TConnectionHandler).GetCustomAttributes <AuthorizeAttribute>(inherit: true);
var options = new HttpConnectionOptions();
foreach (var attribute in authorizeAttributes)
{
options.AuthorizationData.Add(attribute);
}
configureOptions?.Invoke(options);
MapConnections(path, options, builder =>
{
builder.UseConnectionHandler <TConnectionHandler>();
});
}
private Task ProcessNegotiate(HttpContext context, HttpConnectionOptions options, ConnectionLogScope logScope)
{
context.Response.ContentType = "application/json";
// Establish the connection
var connection = _manager.CreateConnection();
// Set the Connection ID on the logging scope so that logs from now on will have the
// Connection ID metadata set.
logScope.ConnectionId = connection.ConnectionId;
// Get the bytes for the connection id
var negotiateResponseBuffer = GetNegotiatePayload(connection.ConnectionId, context, options);
Log.NegotiationRequest(_logger);
// Write it out to the response with the right content length
context.Response.ContentLength = negotiateResponseBuffer.Length;
return(context.Response.Body.WriteAsync(negotiateResponseBuffer, 0, negotiateResponseBuffer.Length));
}
public async Task ExecuteNegotiateAsync(HttpContext context, HttpConnectionOptions options)
{
// Create the log scope and the scope connectionId param will be set when the connection is created.
var logScope = new ConnectionLogScope(connectionId: string.Empty);
using (_logger.BeginScope(logScope))
{
if (!await AuthorizeHelper.AuthorizeAsync(context, options.AuthorizationData))
{
return;
}
if (HttpMethods.IsPost(context.Request.Method))
{
// POST /{path}/negotiate
await ProcessNegotiate(context, options, logScope);
}
else
{
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status405MethodNotAllowed;
}
}
}
// This is only used for WebSockets connections, which can connect directly without negotiating
private async Task <HttpConnectionContext> GetOrCreateConnectionAsync(HttpContext context, HttpConnectionOptions options)
{
var connectionId = GetConnectionId(context);
HttpConnectionContext connection;
// There's no connection id so this is a brand new connection
if (StringValues.IsNullOrEmpty(connectionId))
{
connection = CreateConnection(options);
}
else if (!_manager.TryGetConnection(connectionId, out connection))
{
// No connection with that ID: Not Found
context.Response.StatusCode = StatusCodes.Status404NotFound;
await context.Response.WriteAsync("No Connection with that ID");
return(null);
}
return(connection);
}
private async Task <HttpConnectionContext> GetConnectionAsync(HttpContext context, HttpConnectionOptions options)
{
var connectionId = GetConnectionId(context);
if (StringValues.IsNullOrEmpty(connectionId))
{
// There's no connection ID: bad request
context.Response.StatusCode = StatusCodes.Status400BadRequest;
context.Response.ContentType = "text/plain";
await context.Response.WriteAsync("Connection ID required");
return(null);
}
if (!_manager.TryGetConnection(connectionId, out var connection))
{
// No connection with that ID: Not Found
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
await context.Response.WriteAsync("No Connection with that ID");
return(null);
}
return(connection);
}
private async Task <bool> EnsureConnectionStateAsync(HttpConnectionContext connection, HttpContext context, HttpTransportType transportType, HttpTransportType supportedTransports, ConnectionLogScope logScope, HttpConnectionOptions options)
{
if ((supportedTransports & transportType) == 0)
{
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status404NotFound;
Log.TransportNotSupported(_logger, transportType);
await context.Response.WriteAsync($"{transportType} transport not supported by this end point type");
return(false);
}
// Set the IHttpConnectionFeature now that we can access it.
connection.Features.Set(context.Features.Get <IHttpConnectionFeature>());
if (connection.TransportType == HttpTransportType.None)
{
connection.TransportType = transportType;
connection.Items[ConnectionMetadataNames.Transport] = transportType;
}
else if (connection.TransportType != transportType)
{
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status400BadRequest;
Log.CannotChangeTransport(_logger, connection.TransportType, transportType);
await context.Response.WriteAsync("Cannot change transports mid-connection");
return(false);
}
// Setup the connection state from the http context
connection.User = context.User;
// Configure transport-specific features.
if (transportType == HttpTransportType.LongPolling)
{
connection.Features.Set <IConnectionInherentKeepAliveFeature>(new ConnectionInherentKeepAliveFeature(options.LongPolling.PollTimeout));
// For long polling, the requests come and go but the connection is still alive.
// To make the IHttpContextFeature work well, we make a copy of the relevant properties
// to a new HttpContext. This means that it's impossible to affect the context
// with subsequent requests.
var existing = connection.HttpContext;
if (existing == null)
{
var httpContext = CloneHttpContext(context);
connection.HttpContext = httpContext;
}
else
{
// Set the request trace identifier to the current http request handling the poll
existing.TraceIdentifier = context.TraceIdentifier;
existing.User = context.User;
}
}
else
{
connection.HttpContext = context;
}
// Set the Connection ID on the logging scope so that logs from now on will have the
// Connection ID metadata set.
logScope.ConnectionId = connection.ConnectionId;
return(true);
}
private static void WriteNegotiatePayload(IBufferWriter <byte> writer, string connectionId, HttpContext context, HttpConnectionOptions options)
{
var response = new NegotiationResponse();
response.ConnectionId = connectionId;
response.AvailableTransports = new List <AvailableTransport>();
if ((options.Transports & HttpTransportType.WebSockets) != 0 && ServerHasWebSockets(context.Features))
{
response.AvailableTransports.Add(_webSocketAvailableTransport);
}
if ((options.Transports & HttpTransportType.ServerSentEvents) != 0)
{
response.AvailableTransports.Add(_serverSentEventsAvailableTransport);
}
if ((options.Transports & HttpTransportType.LongPolling) != 0)
{
response.AvailableTransports.Add(_longPollingAvailableTransport);
}
NegotiateProtocol.WriteResponse(response, writer);
}
private async Task ExecuteAsync(HttpContext context, ConnectionDelegate connectionDelegate, HttpConnectionOptions options, ConnectionLogScope logScope)
{
var supportedTransports = options.Transports;
// Server sent events transport
// GET /{path}
// Accept: text/event-stream
var headers = context.Request.GetTypedHeaders();
if (headers.Accept?.Contains(new Net.Http.Headers.MediaTypeHeaderValue("text/event-stream")) == true)
{
// Connection must already exist
var connection = await GetConnectionAsync(context, options);
if (connection == null)
{
// No such connection, GetConnection already set the response status code
return;
}
if (!await EnsureConnectionStateAsync(connection, context, HttpTransportType.ServerSentEvents, supportedTransports, logScope, options))
{
// Bad connection state. It's already set the response status code.
return;
}
Log.EstablishedConnection(_logger);
// ServerSentEvents is a text protocol only
connection.SupportedFormats = TransferFormat.Text;
// We only need to provide the Input channel since writing to the application is handled through /send.
var sse = new ServerSentEventsTransport(connection.Application.Input, connection.ConnectionId, _loggerFactory);
await DoPersistentConnection(connectionDelegate, sse, context, connection);
}
else if (context.WebSockets.IsWebSocketRequest)
{
// Connection can be established lazily
var connection = await GetOrCreateConnectionAsync(context, options);
if (connection == null)
{
// No such connection, GetOrCreateConnection already set the response status code
return;
}
if (!await EnsureConnectionStateAsync(connection, context, HttpTransportType.WebSockets, supportedTransports, logScope, options))
{
// Bad connection state. It's already set the response status code.
return;
}
Log.EstablishedConnection(_logger);
var ws = new WebSocketsTransport(options.WebSockets, connection.Application, connection, _loggerFactory);
await DoPersistentConnection(connectionDelegate, ws, context, connection);
}
else
{
// GET /{path} maps to long polling
// Connection must already exist
var connection = await GetConnectionAsync(context, options);
if (connection == null)
{
// No such connection, GetConnection already set the response status code
return;
}
if (!await EnsureConnectionStateAsync(connection, context, HttpTransportType.LongPolling, supportedTransports, logScope, options))
{
// Bad connection state. It's already set the response status code.
return;
}
try
{
await connection.Lock.WaitAsync();
if (connection.Status == HttpConnectionContext.ConnectionStatus.Disposed)
{
Log.ConnectionDisposed(_logger, connection.ConnectionId);
// The connection was disposed
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
if (connection.Status == HttpConnectionContext.ConnectionStatus.Active)
{
var existing = connection.GetHttpContext();
Log.ConnectionAlreadyActive(_logger, connection.ConnectionId, existing.TraceIdentifier);
using (connection.Cancellation)
{
// Cancel the previous request
connection.Cancellation.Cancel();
// Wait for the previous request to drain
await connection.TransportTask;
Log.PollCanceled(_logger, connection.ConnectionId, existing.TraceIdentifier);
}
}
// Mark the connection as active
connection.Status = HttpConnectionContext.ConnectionStatus.Active;
// Raise OnConnected for new connections only since polls happen all the time
if (connection.ApplicationTask == null)
{
Log.EstablishedConnection(_logger);
connection.ApplicationTask = ExecuteApplication(connectionDelegate, connection);
}
else
{
Log.ResumingConnection(_logger);
}
// REVIEW: Performance of this isn't great as this does a bunch of per request allocations
connection.Cancellation = new CancellationTokenSource();
var timeoutSource = new CancellationTokenSource();
var tokenSource = CancellationTokenSource.CreateLinkedTokenSource(connection.Cancellation.Token, context.RequestAborted, timeoutSource.Token);
// Dispose these tokens when the request is over
context.Response.RegisterForDispose(timeoutSource);
context.Response.RegisterForDispose(tokenSource);
var longPolling = new LongPollingTransport(timeoutSource.Token, connection.Application.Input, connection.ConnectionId, _loggerFactory);
// Start the transport
connection.TransportTask = longPolling.ProcessRequestAsync(context, tokenSource.Token);
// Start the timeout after we return from creating the transport task
timeoutSource.CancelAfter(options.LongPolling.PollTimeout);
}
finally
{
connection.Lock.Release();
}
var resultTask = await Task.WhenAny(connection.ApplicationTask, connection.TransportTask);
var pollAgain = true;
// If the application ended before the transport task then we potentially need to end the connection
if (resultTask == connection.ApplicationTask)
{
// Complete the transport (notifying it of the application error if there is one)
connection.Transport.Output.Complete(connection.ApplicationTask.Exception);
// Wait for the transport to run
await connection.TransportTask;
// If the status code is a 204 it means the connection is done
if (context.Response.StatusCode == StatusCodes.Status204NoContent)
{
// We should be able to safely dispose because there's no more data being written
// We don't need to wait for close here since we've already waited for both sides
await _manager.DisposeAndRemoveAsync(connection, closeGracefully : false);
// Don't poll again if we've removed the connection completely
pollAgain = false;
}
}
else if (context.Response.StatusCode == StatusCodes.Status204NoContent)
{
// Don't poll if the transport task was cancelled
pollAgain = false;
}
if (pollAgain)
{
// Otherwise, we update the state to inactive again and wait for the next poll
try
{
await connection.Lock.WaitAsync();
if (connection.Status == HttpConnectionContext.ConnectionStatus.Active)
{
// Mark the connection as inactive
connection.LastSeenUtc = DateTime.UtcNow;
connection.Status = HttpConnectionContext.ConnectionStatus.Inactive;
// Dispose the cancellation token
connection.Cancellation.Dispose();
connection.Cancellation = null;
}
}
finally
{
connection.Lock.Release();
}
}
}
}
private static byte[] GetNegotiatePayload(string connectionId, HttpContext context, HttpConnectionOptions options)
{
NegotiationResponse response = new NegotiationResponse();
response.ConnectionId = connectionId;
response.AvailableTransports = new List <AvailableTransport>();
if ((options.Transports & TransportType.WebSockets) != 0 && ServerHasWebSockets(context.Features))
{
response.AvailableTransports.Add(_webSocketAvailableTransport);
}
if ((options.Transports & TransportType.ServerSentEvents) != 0)
{
response.AvailableTransports.Add(_serverSentEventsAvailableTransport);
}
if ((options.Transports & TransportType.LongPolling) != 0)
{
response.AvailableTransports.Add(_longPollingAvailableTransport);
}
MemoryStream ms = new MemoryStream();
NegotiateProtocol.WriteResponse(response, ms);
return(ms.ToArray());
}