Observe the route template constraints in the Swagger middleware

Swashbuckle.AspNetCore.sln

@@ -1,4 +1,4 @@
-
+
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
 VisualStudioVersion = 17.0.31717.71
@@ -91,6 +91,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Swashbuckle.AspNetCore.Test
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MinimalApp", "test\WebSites\MinimalApp\MinimalApp.csproj", "{3D0126CB-5439-483C-B2D5-4B4BE111D15C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TopLevelSwaggerDoc", "test\WebSites\TopLevelSwaggerDoc\TopLevelSwaggerDoc.csproj", "{6EA75DA8-9B1F-468E-9425-37F01A129B0F}"
+EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".github", ".github", "{3BA087DA-788C-43D6-9D8B-1EF017014A4A}"
 	ProjectSection(SolutionItems) = preProject
 		.github\actionlint-matcher.json = .github\actionlint-matcher.json
@@ -501,6 +503,18 @@ Global
 		{3D0126CB-5439-483C-B2D5-4B4BE111D15C}.Release|x64.Build.0 = Release|Any CPU
 		{3D0126CB-5439-483C-B2D5-4B4BE111D15C}.Release|x86.ActiveCfg = Release|Any CPU
 		{3D0126CB-5439-483C-B2D5-4B4BE111D15C}.Release|x86.Build.0 = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|x64.Build.0 = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Debug|x86.Build.0 = Debug|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|x64.ActiveCfg = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|x64.Build.0 = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|x86.ActiveCfg = Release|Any CPU
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -539,6 +553,7 @@ Global
 		{76692D68-C38C-4A7D-B3DA-DA78A393E266} = {0ADCB223-F375-45AB-8BC4-834EC9C69554}
 		{66590FBA-5FDD-4AC9-AF91-26ADAB33CCB8} = {0ADCB223-F375-45AB-8BC4-834EC9C69554}
 		{3D0126CB-5439-483C-B2D5-4B4BE111D15C} = {DB3F57FC-1472-4F03-B551-43394DA3C5EB}
+		{6EA75DA8-9B1F-468E-9425-37F01A129B0F} = {DB3F57FC-1472-4F03-B551-43394DA3C5EB}
 		{3BA087DA-788C-43D6-9D8B-1EF017014A4A} = {FA1B4021-0A97-4F68-B966-148191F6AAA8}
 		{A0EC16BE-C520-4FCF-BB54-2D79CD255F00} = {3BA087DA-788C-43D6-9D8B-1EF017014A4A}
 	EndGlobalSection

src/Swashbuckle.AspNetCore.Swagger/DependencyInjection/SwaggerBuilderExtensions.cs

@@ -1,9 +1,10 @@
-using System;
-using System.Linq;
-using Microsoft.AspNetCore.Routing;
+using System;
 
 #if (!NETSTANDARD2_0)
+using System.Linq;
+using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Patterns;
+using Microsoft.AspNetCore.Routing.Template;
 #endif
 
 using Microsoft.Extensions.DependencyInjection;
@@ -19,7 +20,11 @@ public static class SwaggerBuilderExtensions
         /// </summary>
         public static IApplicationBuilder UseSwagger(this IApplicationBuilder app, SwaggerOptions options)
         {
+#if (!NETSTANDARD2_0)
+            return app.UseMiddleware<SwaggerMiddleware>(options, app.ApplicationServices.GetRequiredService<TemplateBinderFactory>());
+#else
             return app.UseMiddleware<SwaggerMiddleware>(options);
+#endif
         }
 
         /// <summary>
@@ -42,7 +47,7 @@ public static IApplicationBuilder UseSwagger(
 #if (!NETSTANDARD2_0)
         public static IEndpointConventionBuilder MapSwagger(
             this IEndpointRouteBuilder endpoints,
-            string pattern = "/swagger/{documentName}/swagger.{json|yaml}",
+            string pattern = "/swagger/{documentName}/swagger.{extension:regex(^(json|ya?ml)$)}",
             Action<SwaggerEndpointOptions> setupAction = null)
         {
             if (!RoutePatternFactory.Parse(pattern).Parameters.Any(x => x.Name == "documentName"))

src/Swashbuckle.AspNetCore.Swagger/SwaggerMiddleware.cs

@@ -4,6 +4,9 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
+#if !NETSTANDARD
+using Microsoft.AspNetCore.Routing.Patterns;
+#endif
 using Microsoft.AspNetCore.Routing.Template;
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Writers;
@@ -15,6 +18,9 @@ public class SwaggerMiddleware
         private readonly RequestDelegate _next;
         private readonly SwaggerOptions _options;
         private readonly TemplateMatcher _requestMatcher;
+#if !NETSTANDARD
+        private readonly TemplateBinder _templateBinder;
+#endif
 
         public SwaggerMiddleware(
             RequestDelegate next,
@@ -25,9 +31,19 @@ public SwaggerMiddleware(
             _requestMatcher = new TemplateMatcher(TemplateParser.Parse(_options.RouteTemplate), new RouteValueDictionary());
         }
 
+#if !NETSTANDARD
+        public SwaggerMiddleware(
+            RequestDelegate next,
+            SwaggerOptions options,
+            TemplateBinderFactory templateBinderFactory) : this(next, options)
+        {
+            _templateBinder = templateBinderFactory.Create(RoutePatternFactory.Parse(_options.RouteTemplate));
+        }
+#endif
+
         public async Task Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
         {
-            if (!RequestingSwaggerDocument(httpContext.Request, out string documentName))
+            if (!RequestingSwaggerDocument(httpContext.Request, out string documentName, out string extension))
             {
                 await _next(httpContext);
                 return;
@@ -57,7 +73,7 @@ public async Task Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvid
                     filter(swagger, httpContext.Request);
                 }
 
-                if (Path.GetExtension(httpContext.Request.Path.Value) == ".yaml")
+                if (extension is ".yaml" or ".yml")
                 {
                     await RespondWithSwaggerYaml(httpContext.Response, swagger);
                 }
@@ -72,16 +88,37 @@ public async Task Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvid
             }
         }
 
-        private bool RequestingSwaggerDocument(HttpRequest request, out string documentName)
+        private bool RequestingSwaggerDocument(HttpRequest request, out string documentName, out string extension)
         {
             documentName = null;
+            extension = null;
             if (request.Method != "GET") return false;
 
             var routeValues = new RouteValueDictionary();
-            if (!_requestMatcher.TryMatch(request.Path, routeValues) || !routeValues.ContainsKey("documentName")) return false;
+            if (_requestMatcher.TryMatch(request.Path, routeValues))
+            {
+#if !NETSTANDARD
+                if (_templateBinder != null && !_templateBinder.TryProcessConstraints(request.HttpContext, routeValues, out _, out _))
+                {
+                    return false;
+                }
+#endif
+                if (routeValues.TryGetValue("documentName", out var documentNameObject) && documentNameObject is string documentNameString)
+                {
+                    documentName = documentNameString;
+                    if (routeValues.TryGetValue("extension", out var extensionObject))
+                    {
+                        extension = $".{extensionObject}";
+                    }
+                    else
+                    {
+                        extension = Path.GetExtension(request.Path.Value);
+                    }
+                    return true;
+                }
+            }
 
-            documentName = routeValues["documentName"].ToString();
-            return true;
+            return false;
         }
 
         private void RespondWithNotFound(HttpResponse response)

src/Swashbuckle.AspNetCore.Swagger/SwaggerOptions.cs

@@ -16,7 +16,7 @@ public SwaggerOptions()
         /// <summary>
         /// Sets a custom route for the Swagger JSON/YAML endpoint(s). Must include the {documentName} parameter
         /// </summary>
-        public string RouteTemplate { get; set; } = "swagger/{documentName}/swagger.{json|yaml}";
+        public string RouteTemplate { get; set; } = "swagger/{documentName}/swagger.{extension:regex(^(json|ya?ml)$)}";
 
         /// <summary>
         /// Return Swagger JSON/YAML in the V2 format rather than V3

test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerAndSwaggerUIIntegrationTests.cs

@@ -0,0 +1,25 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Xunit;
+
+namespace Swashbuckle.AspNetCore.IntegrationTests
+{
+    public class SwaggerAndSwaggerUIIntegrationTests
+    {
+        [Theory]
+        [InlineData("/swagger/index.html", "text/html")]
+        [InlineData("/swagger/v1.json", "application/json")]
+        [InlineData("/swagger/v1.yaml", "text/yaml")]
+        [InlineData("/swagger/v1.yml", "text/yaml")]
+        public async Task SwaggerDocWithoutSubdirectory(string path, string mediaType)
+        {
+            var client = new WebApplicationFactory<TopLevelSwaggerDoc.Program>().CreateClient();
+
+            var response = await client.GetAsync(path);
+
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal(mediaType, response.Content.Headers.ContentType?.MediaType);
+        }
+    }
+}

test/Swashbuckle.AspNetCore.IntegrationTests/Swashbuckle.AspNetCore.IntegrationTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <AssemblyOriginatorKeyFile>Swashbuckle.AspNetCore.IntegrationTests.snk</AssemblyOriginatorKeyFile>
@@ -19,10 +19,11 @@
     <ProjectReference Include="..\WebSites\OAuth2Integration\OAuth2Integration.csproj" />
     <ProjectReference Include="..\WebSites\ReDoc\ReDoc.csproj" />
     <ProjectReference Include="..\WebSites\TestFirst\TestFirst.csproj" />
+    <ProjectReference Include="..\WebSites\TopLevelSwaggerDoc\TopLevelSwaggerDoc.csproj" />
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.TestHost" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
     <PackageReference Include="Microsoft.OpenApi.Readers" />
     <PackageReference Include="xunit" />

test/WebSites/TopLevelSwaggerDoc/Program.cs

@@ -0,0 +1,19 @@
+using Microsoft.OpenApi.Models;
+
+namespace TopLevelSwaggerDoc;
+
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        var builder = WebApplication.CreateBuilder(args);
+        builder.Services.AddMvcCore().AddApiExplorer();
+        builder.Services.AddSwaggerGen(c => c.SwaggerDoc("v1", new OpenApiInfo { Title = "Test API", Version = "1" }));
+        var app = builder.Build();
+
+        app.UseSwagger(c => c.RouteTemplate = c.RouteTemplate.Replace("swagger/{documentName}/swagger.", "swagger/{documentName}."));
+        app.UseSwaggerUI(c => c.SwaggerEndpoint("v1.json", "Test API"));
+
+        app.Run();
+    }
+}

test/WebSites/TopLevelSwaggerDoc/Properties/launchSettings.json

@@ -0,0 +1,28 @@
+{
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:12841",
+      "sslPort": 44316
+    }
+  },
+  "profiles": {
+    "TopLevelSwaggerDoc": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:7028;http://localhost:5225",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

test/WebSites/TopLevelSwaggerDoc/TopLevelSwaggerDoc.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\src\Swashbuckle.AspNetCore.Swagger\Swashbuckle.AspNetCore.Swagger.csproj" />
+    <ProjectReference Include="..\..\..\src\Swashbuckle.AspNetCore.SwaggerGen\Swashbuckle.AspNetCore.SwaggerGen.csproj" />
+    <ProjectReference Include="..\..\..\src\Swashbuckle.AspNetCore.SwaggerUI\Swashbuckle.AspNetCore.SwaggerUI.csproj" />
+  </ItemGroup>
+
+</Project>

test/WebSites/TopLevelSwaggerDoc/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

test/WebSites/TopLevelSwaggerDoc/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}