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|
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Buffers;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.IO.Pipelines;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Connections;
using Microsoft.AspNetCore.Connections.Features;
using Microsoft.AspNetCore.Http.Connections.Features;
using Microsoft.AspNetCore.Http.Connections.Internal.Transports;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Internal;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Primitives;
namespace Microsoft.AspNetCore.Http.Connections.Internal
{
public partial class HttpConnectionDispatcher
{
private static readonly AvailableTransport _webSocketAvailableTransport =
new AvailableTransport
{
Transport = nameof(HttpTransportType.WebSockets),
TransferFormats = new List<string> { nameof(TransferFormat.Text), nameof(TransferFormat.Binary) }
};
private static readonly AvailableTransport _serverSentEventsAvailableTransport =
new AvailableTransport
{
Transport = nameof(HttpTransportType.ServerSentEvents),
TransferFormats = new List<string> { nameof(TransferFormat.Text) }
};
private static readonly AvailableTransport _longPollingAvailableTransport =
new AvailableTransport
{
Transport = nameof(HttpTransportType.LongPolling),
TransferFormats = new List<string> { nameof(TransferFormat.Text), nameof(TransferFormat.Binary) }
};
private readonly HttpConnectionManager _manager;
private readonly ILoggerFactory _loggerFactory;
private readonly ILogger _logger;
public HttpConnectionDispatcher(HttpConnectionManager manager, ILoggerFactory loggerFactory)
{
_manager = manager;
_loggerFactory = loggerFactory;
_logger = _loggerFactory.CreateLogger<HttpConnectionDispatcher>();
}
public async Task ExecuteAsync(HttpContext context, HttpConnectionDispatcherOptions 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 if (HttpMethods.IsDelete(context.Request.Method))
{
// DELETE /{path}
await ProcessDeleteAsync(context);
}
else
{
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status405MethodNotAllowed;
}
}
}
public async Task ExecuteNegotiateAsync(HttpContext context, HttpConnectionDispatcherOptions 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;
}
}
}
private async Task ExecuteAsync(HttpContext context, ConnectionDelegate connectionDelegate, HttpConnectionDispatcherOptions 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);
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);
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;
}
// Create a new Tcs every poll to keep track of the poll finishing, so we can properly wait on previous polls
var currentRequestTcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);
await connection.StateLock.WaitAsync();
try
{
if (connection.Status == HttpConnectionStatus.Disposed)
{
Log.ConnectionDisposed(_logger, connection.ConnectionId);
// The connection was disposed
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
if (connection.Status == HttpConnectionStatus.Active)
{
var existing = connection.GetHttpContext();
Log.ConnectionAlreadyActive(_logger, connection.ConnectionId, existing.TraceIdentifier);
}
using (connection.Cancellation)
{
// Cancel the previous request
connection.Cancellation?.Cancel();
try
{
// Wait for the previous request to drain
await connection.PreviousPollTask;
}
catch (OperationCanceledException)
{
// Previous poll canceled due to connection closing, close this poll too
context.Response.ContentType = "text/plain";
context.Response.StatusCode = StatusCodes.Status204NoContent;
return;
}
connection.PreviousPollTask = currentRequestTcs.Task;
}
// Mark the connection as active
connection.Status = HttpConnectionStatus.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);
context.Response.ContentType = "application/octet-stream";
// This request has no content
context.Response.ContentLength = 0;
// On the first poll, we flush the response immediately to mark the poll as "initialized" so future
// requests can be made safely
connection.TransportTask = context.Response.Body.FlushAsync();
}
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, _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.StateLock.Release();
}
var resultTask = await Task.WhenAny(connection.ApplicationTask, connection.TransportTask);
try
{
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)
{
// Cancel current request to release any waiting poll and let dispose aquire the lock
currentRequestTcs.TrySetCanceled();
// 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 canceled
pollAgain = false;
}
if (pollAgain)
{
// Mark the connection as inactive
connection.LastSeenUtc = DateTime.UtcNow;
connection.Status = HttpConnectionStatus.Inactive;
}
}
finally
{
// Artificial task queue
// This will cause incoming polls to wait until the previous poll has finished updating internal state info
currentRequestTcs.TrySetResult(null);
}
}
}
private async Task DoPersistentConnection(ConnectionDelegate connectionDelegate,
IHttpTransport transport,
HttpContext context,
HttpConnectionContext connection)
{
await connection.StateLock.WaitAsync();
try
{
if (connection.Status == HttpConnectionStatus.Disposed)
{
Log.ConnectionDisposed(_logger, connection.ConnectionId);
// Connection was disposed
context.Response.StatusCode = StatusCodes.Status404NotFound;
return;
}
// There's already an active request
if (connection.Status == HttpConnectionStatus.Active)
{
Log.ConnectionAlreadyActive(_logger, connection.ConnectionId, connection.GetHttpContext().TraceIdentifier);
// Reject the request with a 409 conflict
context.Response.StatusCode = StatusCodes.Status409Conflict;
return;
}
// Mark the connection as active
connection.Status = HttpConnectionStatus.Active;
// Call into the end point passing the connection
connection.ApplicationTask = ExecuteApplication(connectionDelegate, connection);
// Start the transport
connection.TransportTask = transport.ProcessRequestAsync(context, context.RequestAborted);
}
finally
{
connection.StateLock.Release();
}
// Wait for any of them to end
await Task.WhenAny(connection.ApplicationTask, connection.TransportTask);
await _manager.DisposeAndRemoveAsync(connection, closeGracefully: true);
}
private async Task ExecuteApplication(ConnectionDelegate connectionDelegate, HttpConnectionContext connection)
{
// Verify some initialization invariants
Debug.Assert(connection.TransportType != HttpTransportType.None, "Transport has not been initialized yet");
// Jump onto the thread pool thread so blocking user code doesn't block the setup of the
// connection and transport
await AwaitableThreadPool.Yield();
// Running this in an async method turns sync exceptions into async ones
await connectionDelegate(connection);
}
private async Task ProcessNegotiate(HttpContext context, HttpConnectionDispatcherOptions 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 static void WriteNegotiatePayload(IBufferWriter<byte> writer, string connectionId, HttpContext context, HttpConnectionDispatcherOptions 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 static bool ServerHasWebSockets(IFeatureCollection features)
{
return features.Get<IHttpWebSocketFeature>() != null;
}
private static string GetConnectionId(HttpContext context) => context.Request.Query["id"];
private async Task ProcessSend(HttpContext context, HttpConnectionDispatcherOptions options)
{
var connection = await GetConnectionAsync(context);
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;
await connection.WriteLock.WaitAsync();
try
{
if (connection.Status == HttpConnectionStatus.Disposed)
{
Log.ConnectionDisposed(_logger, connection.ConnectionId);
// The connection was disposed
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
try
{
try
{
await context.Request.Body.CopyToAsync(connection.ApplicationStream, bufferSize);
}
catch (InvalidOperationException ex)
{
// PipeWriter will throw an error if it is written to while dispose is in progress and the writer has been completed
// Dispose isn't taking WriteLock because it could be held because of backpressure, and calling CancelPendingFlush
// then taking the lock introduces a race condition that could lead to a deadlock
Log.ConnectionDisposedWhileWriteInProgress(_logger, connection.ConnectionId, ex);
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
catch (OperationCanceledException)
{
// CancelPendingFlush has canceled pending writes caused by backpresure
Log.ConnectionDisposed(_logger, connection.ConnectionId);
context.Response.StatusCode = StatusCodes.Status404NotFound;
context.Response.ContentType = "text/plain";
return;
}
Log.ReceivedBytes(_logger, connection.ApplicationStream.Length);
}
finally
{
// Clear the amount of read bytes so logging is accurate
connection.ApplicationStream.Reset();
}
}
finally
{
connection.WriteLock.Release();
}
}
private async Task ProcessDeleteAsync(HttpContext context)
{
var connection = await GetConnectionAsync(context);
if (connection == null)
{
// No such connection, GetConnection already set the response status code
return;
}
// This end point only works for long polling
if (connection.TransportType != HttpTransportType.LongPolling)
{
Log.ReceivedDeleteRequestForUnsupportedTransport(_logger, connection.TransportType);
context.Response.StatusCode = StatusCodes.Status400BadRequest;
context.Response.ContentType = "text/plain";
await context.Response.WriteAsync("Cannot terminate this connection using the DELETE endpoint.");
return;
}
Log.TerminatingConection(_logger);
// Complete the receiving end of the pipe
connection.Application.Output.Complete();
// Dispose the connection gracefully, but don't wait for it. We assign it here so we can wait in tests
connection.DisposeAndRemoveTask = _manager.DisposeAndRemoveAsync(connection, closeGracefully: true);
context.Response.StatusCode = StatusCodes.Status202Accepted;
context.Response.ContentType = "text/plain";
}
private async Task<bool> EnsureConnectionStateAsync(HttpConnectionContext connection, HttpContext context, HttpTransportType transportType, HttpTransportType supportedTransports, ConnectionLogScope logScope, HttpConnectionDispatcherOptions 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;
}
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.HasInherentKeepAlive = true;
// 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 HttpContext CloneHttpContext(HttpContext context)
{
// The reason we're copying the base features instead of the HttpContext properties is
// so that we can get all of the logic built into DefaultHttpContext to extract higher level
// structure from the low level properties
var existingRequestFeature = context.Features.Get<IHttpRequestFeature>();
var requestFeature = new HttpRequestFeature();
requestFeature.Protocol = existingRequestFeature.Protocol;
requestFeature.Method = existingRequestFeature.Method;
requestFeature.Scheme = existingRequestFeature.Scheme;
requestFeature.Path = existingRequestFeature.Path;
requestFeature.PathBase = existingRequestFeature.PathBase;
requestFeature.QueryString = existingRequestFeature.QueryString;
requestFeature.RawTarget = existingRequestFeature.RawTarget;
var requestHeaders = new Dictionary<string, StringValues>(existingRequestFeature.Headers.Count, StringComparer.Ordinal);
foreach (var header in existingRequestFeature.Headers)
{
requestHeaders[header.Key] = header.Value;
}
requestFeature.Headers = new HeaderDictionary(requestHeaders);
var existingConnectionFeature = context.Features.Get<IHttpConnectionFeature>();
var connectionFeature = new HttpConnectionFeature();
if (existingConnectionFeature != null)
{
connectionFeature.ConnectionId = existingConnectionFeature.ConnectionId;
connectionFeature.LocalIpAddress = existingConnectionFeature.LocalIpAddress;
connectionFeature.LocalPort = existingConnectionFeature.LocalPort;
connectionFeature.RemoteIpAddress = existingConnectionFeature.RemoteIpAddress;
connectionFeature.RemotePort = existingConnectionFeature.RemotePort;
}
// The response is a dud, you can't do anything with it anyways
var responseFeature = new HttpResponseFeature();
var features = new FeatureCollection();
features.Set<IHttpRequestFeature>(requestFeature);
features.Set<IHttpResponseFeature>(responseFeature);
features.Set<IHttpConnectionFeature>(connectionFeature);
// REVIEW: We could strategically look at adding other features but it might be better
// if we expose a callback that would allow the user to preserve HttpContext properties.
var newHttpContext = new DefaultHttpContext(features);
newHttpContext.TraceIdentifier = context.TraceIdentifier;
newHttpContext.User = context.User;
// Making request services function property could be tricky and expensive as it would require
// DI scope per connection. It would also mean that services resolved in middleware leading up to here
// wouldn't be the same instance (but maybe that's fine). For now, we just return an empty service provider
newHttpContext.RequestServices = EmptyServiceProvider.Instance;
// REVIEW: This extends the lifetime of anything that got put into HttpContext.Items
newHttpContext.Items = new Dictionary<object, object>(context.Items);
return newHttpContext;
}
private async Task<HttpConnectionContext> GetConnectionAsync(HttpContext context)
{
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;
}
// This is only used for WebSockets connections, which can connect directly without negotiating
private async Task<HttpConnectionContext> GetOrCreateConnectionAsync(HttpContext context, HttpConnectionDispatcherOptions 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 HttpConnectionContext CreateConnection(HttpConnectionDispatcherOptions 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 class EmptyServiceProvider : IServiceProvider
{
public static EmptyServiceProvider Instance { get; } = new EmptyServiceProvider();
public object GetService(Type serviceType) => null;
}
}
}
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