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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 Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
namespace Microsoft.AspNetCore.Builder;
/// <summary>
/// Constains extensions for configuring routing on an <see cref="IApplicationBuilder"/>.
/// </summary>
public static class EndpointRoutingApplicationBuilderExtensions
{
private const string EndpointRouteBuilder = "__EndpointRouteBuilder";
private const string GlobalEndpointRouteBuilderKey = "__GlobalEndpointRouteBuilder";
/// <summary>
/// Adds a <see cref="EndpointRoutingMiddleware"/> middleware to the specified <see cref="IApplicationBuilder"/>.
/// </summary>
/// <param name="builder">The <see cref="IApplicationBuilder"/> to add the middleware to.</param>
/// <returns>A reference to this instance after the operation has completed.</returns>
/// <remarks>
/// <para>
/// A call to <see cref="UseRouting(IApplicationBuilder)"/> must be followed by a call to
/// <see cref="UseEndpoints(IApplicationBuilder, Action{IEndpointRouteBuilder})"/> for the same <see cref="IApplicationBuilder"/>
/// instance.
/// </para>
/// <para>
/// The <see cref="EndpointRoutingMiddleware"/> defines a point in the middleware pipeline where routing decisions are
/// made, and an <see cref="Endpoint"/> is associated with the <see cref="HttpContext"/>. The <see cref="EndpointMiddleware"/>
/// defines a point in the middleware pipeline where the current <see cref="Endpoint"/> is executed. Middleware between
/// the <see cref="EndpointRoutingMiddleware"/> and <see cref="EndpointMiddleware"/> may observe or change the
/// <see cref="Endpoint"/> associated with the <see cref="HttpContext"/>.
/// </para>
/// </remarks>
public static IApplicationBuilder UseRouting(this IApplicationBuilder builder)
{
if (builder == null)
{
throw new ArgumentNullException(nameof(builder));
}
VerifyRoutingServicesAreRegistered(builder);
IEndpointRouteBuilder endpointRouteBuilder;
if (builder.Properties.TryGetValue(GlobalEndpointRouteBuilderKey, out var obj))
{
endpointRouteBuilder = (IEndpointRouteBuilder)obj!;
// Let interested parties know if UseRouting() was called while a global route builder was set
builder.Properties[EndpointRouteBuilder] = endpointRouteBuilder;
}
else
{
endpointRouteBuilder = new DefaultEndpointRouteBuilder(builder);
builder.Properties[EndpointRouteBuilder] = endpointRouteBuilder;
}
return builder.UseMiddleware<EndpointRoutingMiddleware>(endpointRouteBuilder);
}
/// <summary>
/// Adds a <see cref="EndpointMiddleware"/> middleware to the specified <see cref="IApplicationBuilder"/>
/// with the <see cref="EndpointDataSource"/> instances built from configured <see cref="IEndpointRouteBuilder"/>.
/// The <see cref="EndpointMiddleware"/> will execute the <see cref="Endpoint"/> associated with the current
/// request.
/// </summary>
/// <param name="builder">The <see cref="IApplicationBuilder"/> to add the middleware to.</param>
/// <param name="configure">An <see cref="Action{IEndpointRouteBuilder}"/> to configure the provided <see cref="IEndpointRouteBuilder"/>.</param>
/// <returns>A reference to this instance after the operation has completed.</returns>
/// <remarks>
/// <para>
/// A call to <see cref="UseEndpoints(IApplicationBuilder, Action{IEndpointRouteBuilder})"/> must be preceded by a call to
/// <see cref="UseRouting(IApplicationBuilder)"/> for the same <see cref="IApplicationBuilder"/>
/// instance.
/// </para>
/// <para>
/// The <see cref="EndpointRoutingMiddleware"/> defines a point in the middleware pipeline where routing decisions are
/// made, and an <see cref="Endpoint"/> is associated with the <see cref="HttpContext"/>. The <see cref="EndpointMiddleware"/>
/// defines a point in the middleware pipeline where the current <see cref="Endpoint"/> is executed. Middleware between
/// the <see cref="EndpointRoutingMiddleware"/> and <see cref="EndpointMiddleware"/> may observe or change the
/// <see cref="Endpoint"/> associated with the <see cref="HttpContext"/>.
/// </para>
/// </remarks>
public static IApplicationBuilder UseEndpoints(this IApplicationBuilder builder, Action<IEndpointRouteBuilder> configure)
{
if (builder == null)
{
throw new ArgumentNullException(nameof(builder));
}
if (configure == null)
{
throw new ArgumentNullException(nameof(configure));
}
VerifyRoutingServicesAreRegistered(builder);
VerifyEndpointRoutingMiddlewareIsRegistered(builder, out var endpointRouteBuilder);
configure(endpointRouteBuilder);
// Yes, this mutates an IOptions. We're registering data sources in a global collection which
// can be used for discovery of endpoints or URL generation.
//
// Each middleware gets its own collection of data sources, and all of those data sources also
// get added to a global collection.
var routeOptions = builder.ApplicationServices.GetRequiredService<IOptions<RouteOptions>>();
foreach (var dataSource in endpointRouteBuilder.DataSources)
{
if (!routeOptions.Value.EndpointDataSources.Contains(dataSource))
{
routeOptions.Value.EndpointDataSources.Add(dataSource);
}
}
return builder.UseMiddleware<EndpointMiddleware>();
}
private static void VerifyRoutingServicesAreRegistered(IApplicationBuilder app)
{
// Verify if AddRouting was done before calling UseEndpointRouting/UseEndpoint
// We use the RoutingMarkerService to make sure if all the services were added.
if (app.ApplicationServices.GetService(typeof(RoutingMarkerService)) == null)
{
throw new InvalidOperationException(Resources.FormatUnableToFindServices(
nameof(IServiceCollection),
nameof(RoutingServiceCollectionExtensions.AddRouting),
"ConfigureServices(...)"));
}
}
private static void VerifyEndpointRoutingMiddlewareIsRegistered(IApplicationBuilder app, out IEndpointRouteBuilder endpointRouteBuilder)
{
if (!app.Properties.TryGetValue(EndpointRouteBuilder, out var obj))
{
var message =
$"{nameof(EndpointRoutingMiddleware)} matches endpoints setup by {nameof(EndpointMiddleware)} and so must be added to the request " +
$"execution pipeline before {nameof(EndpointMiddleware)}. " +
$"Please add {nameof(EndpointRoutingMiddleware)} by calling '{nameof(IApplicationBuilder)}.{nameof(UseRouting)}' inside the call " +
$"to 'Configure(...)' in the application startup code.";
throw new InvalidOperationException(message);
}
endpointRouteBuilder = (IEndpointRouteBuilder)obj!;
// This check handles the case where Map or something else that forks the pipeline is called between the two
// routing middleware.
if (endpointRouteBuilder is DefaultEndpointRouteBuilder defaultRouteBuilder && !object.ReferenceEquals(app, defaultRouteBuilder.ApplicationBuilder))
{
var message =
$"The {nameof(EndpointRoutingMiddleware)} and {nameof(EndpointMiddleware)} must be added to the same {nameof(IApplicationBuilder)} instance. " +
$"To use Endpoint Routing with 'Map(...)', make sure to call '{nameof(IApplicationBuilder)}.{nameof(UseRouting)}' before " +
$"'{nameof(IApplicationBuilder)}.{nameof(UseEndpoints)}' for each branch of the middleware pipeline.";
throw new InvalidOperationException(message);
}
}
}