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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Diagnostics;
using System.IO.Pipelines;
using System.Linq;
using Microsoft.AspNetCore.Connections;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Microsoft.Extensions.Primitives;
namespace Microsoft.AspNetCore.Server.Kestrel.Core;
internal sealed class KestrelServerImpl : IServer
{
private readonly ServerAddressesFeature _serverAddresses;
private readonly TransportManager _transportManager;
private readonly List<IConnectionListenerFactory> _transportFactories;
private readonly List<IMultiplexedConnectionListenerFactory> _multiplexedTransportFactories;
private readonly IHttpsConfigurationService _httpsConfigurationService;
private readonly SemaphoreSlim _bindSemaphore = new SemaphoreSlim(initialCount: 1);
private bool _hasStarted;
private int _stopping;
private readonly CancellationTokenSource _stopCts = new CancellationTokenSource();
private readonly TaskCompletionSource _stoppedTcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
private IDisposable? _configChangedRegistration;
public KestrelServerImpl(
IOptions<KestrelServerOptions> options,
IEnumerable<IConnectionListenerFactory> transportFactories,
IEnumerable<IMultiplexedConnectionListenerFactory> multiplexedFactories,
IHttpsConfigurationService httpsConfigurationService,
ILoggerFactory loggerFactory,
KestrelMetrics metrics)
: this(transportFactories, multiplexedFactories, httpsConfigurationService, CreateServiceContext(options, loggerFactory, diagnosticSource: null, metrics))
{
}
// For testing
internal KestrelServerImpl(
IEnumerable<IConnectionListenerFactory> transportFactories,
IEnumerable<IMultiplexedConnectionListenerFactory> multiplexedFactories,
IHttpsConfigurationService httpsConfigurationService,
ServiceContext serviceContext)
{
ArgumentNullException.ThrowIfNull(transportFactories);
_transportFactories = transportFactories.Reverse().ToList();
_multiplexedTransportFactories = multiplexedFactories.Reverse().ToList();
_httpsConfigurationService = httpsConfigurationService;
if (_transportFactories.Count == 0 && _multiplexedTransportFactories.Count == 0)
{
throw new InvalidOperationException(CoreStrings.TransportNotFound);
}
ServiceContext = serviceContext;
Features = new FeatureCollection();
_serverAddresses = new ServerAddressesFeature();
Features.Set<IServerAddressesFeature>(_serverAddresses);
_transportManager = new TransportManager(_transportFactories, _multiplexedTransportFactories, _httpsConfigurationService, ServiceContext);
}
private static ServiceContext CreateServiceContext(IOptions<KestrelServerOptions> options, ILoggerFactory loggerFactory, DiagnosticSource? diagnosticSource, KestrelMetrics metrics)
{
ArgumentNullException.ThrowIfNull(options);
ArgumentNullException.ThrowIfNull(loggerFactory);
var serverOptions = options.Value ?? new KestrelServerOptions();
var trace = new KestrelTrace(loggerFactory);
var connectionManager = new ConnectionManager(
trace,
serverOptions.Limits.MaxConcurrentUpgradedConnections);
var dateHeaderValueManager = new DateHeaderValueManager(TimeProvider.System);
var heartbeat = new Heartbeat(
new IHeartbeatHandler[] { dateHeaderValueManager, connectionManager },
TimeProvider.System,
DebuggerWrapper.Singleton,
trace,
Heartbeat.Interval);
return new ServiceContext
{
Log = trace,
Scheduler = PipeScheduler.ThreadPool,
HttpParser = new HttpParser<Http1ParsingHandler>(trace.IsEnabled(LogLevel.Information), serverOptions.DisableHttp1LineFeedTerminators),
TimeProvider = TimeProvider.System,
DateHeaderValueManager = dateHeaderValueManager,
ConnectionManager = connectionManager,
Heartbeat = heartbeat,
ServerOptions = serverOptions,
DiagnosticSource = diagnosticSource,
Metrics = metrics
};
}
public IFeatureCollection Features { get; }
public KestrelServerOptions Options => ServiceContext.ServerOptions;
private ServiceContext ServiceContext { get; }
private KestrelTrace Trace => ServiceContext.Log;
private AddressBindContext? AddressBindContext { get; set; }
public async Task StartAsync<TContext>(IHttpApplication<TContext> application, CancellationToken cancellationToken) where TContext : notnull
{
try
{
ValidateOptions();
if (_hasStarted)
{
// The server has already started and/or has not been cleaned up yet
throw new InvalidOperationException(CoreStrings.ServerAlreadyStarted);
}
_hasStarted = true;
ServiceContext.Heartbeat?.Start();
async Task OnBind(ListenOptions options, CancellationToken onBindCancellationToken)
{
var hasHttp1 = options.Protocols.HasFlag(HttpProtocols.Http1);
var hasHttp2 = options.Protocols.HasFlag(HttpProtocols.Http2);
var hasHttp3 = options.Protocols.HasFlag(HttpProtocols.Http3);
var hasTls = options.IsTls;
// Filter out invalid combinations.
if (!hasTls)
{
// Http/1 without TLS, no-op HTTP/2 and 3.
if (hasHttp1)
{
if (options.ProtocolsSetExplicitly)
{
if (hasHttp2)
{
Trace.Http2DisabledWithHttp1AndNoTls(options.EndPoint);
}
if (hasHttp3)
{
Trace.Http3DisabledWithHttp1AndNoTls(options.EndPoint);
}
}
hasHttp2 = false;
hasHttp3 = false;
}
// Http/3 requires TLS. Note we only let it fall back to HTTP/1, not HTTP/2
else if (hasHttp3)
{
throw new InvalidOperationException("HTTP/3 requires HTTPS.");
}
}
// Quic isn't registered if it's not supported, throw if we can't fall back to 1 or 2
if (hasHttp3 && _multiplexedTransportFactories.Count == 0 && !(hasHttp1 || hasHttp2))
{
throw new InvalidOperationException("Unable to bind an HTTP/3 endpoint. This could be because QUIC has not been configured using UseQuic, or the platform doesn't support QUIC or HTTP/3.");
}
// Disable adding alt-svc header if endpoint has configured not to or there is no
// multiplexed transport factory, which happens if QUIC isn't supported.
var addAltSvcHeader = !options.DisableAltSvcHeader && _multiplexedTransportFactories.Count > 0;
var configuredEndpoint = options.EndPoint;
// Add the HTTP middleware as the terminal connection middleware
if (hasHttp1 || hasHttp2
|| options.Protocols == HttpProtocols.None) // TODO a test fails because it doesn't throw an exception in the right place
// when there is no HttpProtocols in KestrelServer, can we remove/change the test?
{
if (_transportFactories.Count == 0)
{
throw new InvalidOperationException($"Cannot start HTTP/1.x or HTTP/2 server if no {nameof(IConnectionListenerFactory)} is registered.");
}
options.UseHttpServer(ServiceContext, application, options.Protocols, addAltSvcHeader);
var connectionDelegate = options.Build();
// Add the connection limit middleware
connectionDelegate = EnforceConnectionLimit(connectionDelegate, Options.Limits.MaxConcurrentConnections, Trace, ServiceContext.Metrics);
options.EndPoint = await _transportManager.BindAsync(configuredEndpoint, connectionDelegate, options.EndpointConfig, onBindCancellationToken).ConfigureAwait(false);
}
if (hasHttp3 && _multiplexedTransportFactories.Count > 0)
{
// Check if a previous transport has changed the endpoint. If it has then the endpoint is dynamic and we can't guarantee it will work for other transports.
// For more details, see https://github.com/dotnet/aspnetcore/issues/42982
if (!configuredEndpoint.Equals(options.EndPoint))
{
Trace.LogError(CoreStrings.DynamicPortOnMultipleTransportsNotSupported);
}
else
{
options.UseHttp3Server(ServiceContext, application, options.Protocols, addAltSvcHeader);
var multiplexedConnectionDelegate = ((IMultiplexedConnectionBuilder)options).Build();
// Add the connection limit middleware
multiplexedConnectionDelegate = EnforceConnectionLimit(multiplexedConnectionDelegate, Options.Limits.MaxConcurrentConnections, Trace, ServiceContext.Metrics);
options.EndPoint = await _transportManager.BindAsync(configuredEndpoint, multiplexedConnectionDelegate, options, onBindCancellationToken).ConfigureAwait(false);
}
}
}
AddressBindContext = new AddressBindContext(_serverAddresses, Options, Trace, OnBind);
await BindAsync(cancellationToken).ConfigureAwait(false);
}
catch
{
// Don't log the error https://github.com/dotnet/aspnetcore/issues/29801
Dispose();
throw;
}
// Register the options with the event source so it can be logged (if necessary)
KestrelEventSource.Log.AddServerOptions(Options);
}
// Graceful shutdown if possible
public async Task StopAsync(CancellationToken cancellationToken)
{
if (Interlocked.Exchange(ref _stopping, 1) == 1)
{
await _stoppedTcs.Task.ConfigureAwait(false);
return;
}
// Stop background heartbeat first.
// The heartbeat running as the server is shutting down could produce unexpected behavior.
ServiceContext.Heartbeat?.Dispose();
_stopCts.Cancel();
#pragma warning disable CA2016 // Don't use cancellationToken when acquiring the semaphore. Dispose calls this with a pre-canceled token.
await _bindSemaphore.WaitAsync().ConfigureAwait(false);
#pragma warning restore CA2016
try
{
await _transportManager.StopAsync(cancellationToken).ConfigureAwait(false);
}
catch (Exception ex)
{
_stoppedTcs.TrySetException(ex);
throw;
}
finally
{
_configChangedRegistration?.Dispose();
_stopCts.Dispose();
_bindSemaphore.Release();
}
_stoppedTcs.TrySetResult();
// Remove the options from the event source so we don't have a leak if
// the server is stopped and started again in the same process.
KestrelEventSource.Log.RemoveServerOptions(Options);
}
// Ungraceful shutdown
public void Dispose()
{
StopAsync(new CancellationToken(canceled: true)).GetAwaiter().GetResult();
}
private async Task BindAsync(CancellationToken cancellationToken)
{
await _bindSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
try
{
if (_stopping == 1)
{
throw new InvalidOperationException("Kestrel has already been stopped.");
}
IChangeToken? reloadToken = null;
_serverAddresses.InternalCollection.PreventPublicMutation();
if (Options.ConfigurationLoader?.ReloadOnChange == true && (!_serverAddresses.PreferHostingUrls || _serverAddresses.InternalCollection.Count == 0))
{
reloadToken = Options.ConfigurationLoader.GetReloadToken();
}
Options.ConfigurationLoader?.LoadInternal();
Options.ConfigurationLoader?.ProcessEndpointsToAdd();
await AddressBinder.BindAsync(Options.GetListenOptions(), AddressBindContext!, _httpsConfigurationService.UseHttpsWithDefaults, cancellationToken).ConfigureAwait(false);
_configChangedRegistration = reloadToken?.RegisterChangeCallback(TriggerRebind, this);
}
finally
{
_bindSemaphore.Release();
}
}
private static void TriggerRebind(object? state)
{
if (state is KestrelServerImpl server)
{
_ = server.RebindAsync();
}
}
private async Task RebindAsync()
{
// Prevents from interfering with shutdown or other rebinds.
// All exceptions are caught and logged at the critical level.
await _bindSemaphore.WaitAsync();
IChangeToken? reloadToken = null;
try
{
if (_stopping == 1)
{
return;
}
Debug.Assert(Options.ConfigurationLoader != null, "Rebind can only happen when there is a ConfigurationLoader.");
reloadToken = Options.ConfigurationLoader.GetReloadToken();
var (endpointsToStop, endpointsToStart) = Options.ConfigurationLoader.Reload();
Trace.LogDebug("Config reload token fired. Checking for changes...");
if (endpointsToStop.Count > 0)
{
var urlsToStop = endpointsToStop.Select(lo => lo.EndpointConfig!.Url);
if (Trace.IsEnabled(LogLevel.Information))
{
Trace.LogInformation("Config changed. Stopping the following endpoints: '{endpoints}'", string.Join("', '", urlsToStop));
}
// 5 is the default value for WebHost's "shutdownTimeoutSeconds", so use that.
using var cts = CancellationTokenSource.CreateLinkedTokenSource(_stopCts.Token);
cts.CancelAfter(TimeSpan.FromSeconds(5));
// TODO: It would be nice to start binding to new endpoints immediately and reconfigured endpoints as soon
// as the unbinding finished for the given endpoint rather than wait for all transports to unbind first.
var configsToStop = new List<EndpointConfig>(endpointsToStop.Count);
foreach (var lo in endpointsToStop)
{
configsToStop.Add(lo.EndpointConfig!);
}
await _transportManager.StopEndpointsAsync(configsToStop, cts.Token).ConfigureAwait(false);
foreach (var listenOption in endpointsToStop)
{
Options.OptionsInUse.Remove(listenOption);
_serverAddresses.InternalCollection.Remove(listenOption.GetDisplayName());
}
}
if (endpointsToStart.Count > 0)
{
var urlsToStart = endpointsToStart.Select(lo => lo.EndpointConfig!.Url);
if (Trace.IsEnabled(LogLevel.Information))
{
Trace.LogInformation("Config changed. Starting the following endpoints: '{endpoints}'", string.Join("', '", urlsToStart));
}
foreach (var listenOption in endpointsToStart)
{
try
{
await listenOption.BindAsync(AddressBindContext!, _stopCts.Token).ConfigureAwait(false);
}
catch (Exception ex)
{
if (Trace.IsEnabled(LogLevel.Critical))
{
Trace.LogCritical(0, ex, "Unable to bind to '{url}' on config reload.", listenOption.EndpointConfig!.Url);
}
}
}
}
}
catch (Exception ex)
{
Trace.LogCritical(0, ex, "Unable to reload configuration.");
}
finally
{
_configChangedRegistration = reloadToken?.RegisterChangeCallback(TriggerRebind, this);
_bindSemaphore.Release();
}
}
private void ValidateOptions()
{
if (Options.Limits.MaxRequestBufferSize.HasValue &&
Options.Limits.MaxRequestBufferSize < Options.Limits.MaxRequestLineSize)
{
throw new InvalidOperationException(
CoreStrings.FormatMaxRequestBufferSmallerThanRequestLineBuffer(Options.Limits.MaxRequestBufferSize.Value, Options.Limits.MaxRequestLineSize));
}
if (Options.Limits.MaxRequestBufferSize.HasValue &&
Options.Limits.MaxRequestBufferSize < Options.Limits.MaxRequestHeadersTotalSize)
{
throw new InvalidOperationException(
CoreStrings.FormatMaxRequestBufferSmallerThanRequestHeaderBuffer(Options.Limits.MaxRequestBufferSize.Value, Options.Limits.MaxRequestHeadersTotalSize));
}
}
private static ConnectionDelegate EnforceConnectionLimit(ConnectionDelegate innerDelegate, long? connectionLimit, KestrelTrace trace, KestrelMetrics metrics)
{
if (!connectionLimit.HasValue)
{
return innerDelegate;
}
return new ConnectionLimitMiddleware<ConnectionContext>(c => innerDelegate(c), connectionLimit.Value, trace, metrics).OnConnectionAsync;
}
private static MultiplexedConnectionDelegate EnforceConnectionLimit(MultiplexedConnectionDelegate innerDelegate, long? connectionLimit, KestrelTrace trace, KestrelMetrics metrics)
{
if (!connectionLimit.HasValue)
{
return innerDelegate;
}
return new ConnectionLimitMiddleware<MultiplexedConnectionContext>(c => innerDelegate(c), connectionLimit.Value, trace, metrics).OnConnectionAsync;
}
}
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