Port the sign-out integration tests and add validation to prevent sign-out from being triggered from unsupported endpoints

src/OpenIddict.Server/OpenIddictServerHandlers.cs

@@ -98,7 +98,12 @@ public static partial class OpenIddictServerHandlers
 
             BeautifyUserCode.Descriptor,
             AttachAccessTokenProperties.Descriptor,
-            AttachDeviceCodeProperties.Descriptor)
+            AttachDeviceCodeProperties.Descriptor,
+
+            /*
+             * Sign-out processing:
+             */
+            ValidateSignOutDemand.Descriptor)
 
             .AddRange(Authentication.DefaultHandlers)
             .AddRange(Device.DefaultHandlers)
@@ -4052,5 +4057,43 @@ public ValueTask HandleAsync([NotNull] ProcessSignInContext context)
                 return default;
             }
         }
+
+        /// <summary>
+        /// Contains the logic responsible of ensuring that the sign-out demand
+        /// is compatible with the type of the endpoint that handled the request.
+        /// </summary>
+        public class ValidateSignOutDemand : IOpenIddictServerHandler<ProcessSignOutContext>
+        {
+            /// <summary>
+            /// Gets the default descriptor definition assigned to this handler.
+            /// </summary>
+            public static OpenIddictServerHandlerDescriptor Descriptor { get; }
+                = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessSignOutContext>()
+                    .UseSingletonHandler<ValidateSignOutDemand>()
+                    .SetOrder(int.MinValue + 100_000)
+                    .Build();
+
+            /// <summary>
+            /// Processes the event.
+            /// </summary>
+            /// <param name="context">The context associated with the event to process.</param>
+            /// <returns>
+            /// A <see cref="ValueTask"/> that can be used to monitor the asynchronous operation.
+            /// </returns>
+            public ValueTask HandleAsync([NotNull] ProcessSignOutContext context)
+            {
+                if (context == null)
+                {
+                    throw new ArgumentNullException(nameof(context));
+                }
+
+                if (context.EndpointType != OpenIddictServerEndpointType.Logout)
+                {
+                    throw new InvalidOperationException("An OpenID Connect response cannot be returned from this endpoint.");
+                }
+
+                return default;
+            }
+        }
     }
 }

test/OpenIddict.Server.IntegrationTests/OpenIddictServerIntegrationTests.cs

@@ -1646,7 +1646,7 @@ public async Task ProcessSignIn_AnIdentityTokenIsReturnedForCustomGrantRequests(
         [InlineData(null, "custom_description", "custom_uri")]
         [InlineData(null, null, "custom_uri")]
         [InlineData(null, null, null)]
-        public async Task ProcessSignIn_AllowsRejectingAuthorizationRequest(string error, string description, string uri)
+        public async Task ProcessSignIn_AllowsRejectingRequest(string error, string description, string uri)
         {
             // Arrange
             var client = CreateClient(options =>
@@ -1677,44 +1677,6 @@ public async Task ProcessSignIn_AllowsRejectingAuthorizationRequest(string error
             Assert.Equal(uri, response.ErrorUri);
         }
 
-        [Theory]
-        [InlineData("custom_error", null, null)]
-        [InlineData("custom_error", "custom_description", null)]
-        [InlineData("custom_error", "custom_description", "custom_uri")]
-        [InlineData(null, "custom_description", null)]
-        [InlineData(null, "custom_description", "custom_uri")]
-        [InlineData(null, null, "custom_uri")]
-        [InlineData(null, null, null)]
-        public async Task ProcessSignIn_AllowsRejectingTokenRequest(string error, string description, string uri)
-        {
-            // Arrange
-            var client = CreateClient(options =>
-            {
-                options.EnableDegradedMode();
-
-                options.AddEventHandler<ProcessSignInContext>(builder =>
-                    builder.UseInlineHandler(context =>
-                    {
-                        context.Reject(error, description, uri);
-
-                        return default;
-                    }));
-            });
-
-            // Act
-            var response = await client.PostAsync("/connect/token", new OpenIddictRequest
-            {
-                GrantType = GrantTypes.Password,
-                Username = "johndoe",
-                Password = "A3ddj3w"
-            });
-
-            // Assert
-            Assert.Equal(error ?? Errors.InvalidRequest, response.Error);
-            Assert.Equal(description, response.ErrorDescription);
-            Assert.Equal(uri, response.ErrorUri);
-        }
-
         [Fact]
         public async Task ProcessSignIn_AllowsHandlingResponse()
         {
@@ -2834,6 +2796,95 @@ public async Task ProcessSignIn_AdHocAuthorizationIsNotCreatedWhenAuthorizationS
             Mock.Get(manager).Verify(manager => manager.CreateAsync(It.IsAny<OpenIddictAuthorizationDescriptor>(), It.IsAny<CancellationToken>()), Times.Never());
         }
 
+        [Fact]
+        public async Task ProcessSignOut_InvalidEndpointCausesAnException()
+        {
+            // Arrange
+            var client = CreateClient(options =>
+            {
+                options.EnableDegradedMode();
+                options.SetConfigurationEndpointUris("/signout");
+
+                options.AddEventHandler<HandleConfigurationRequestContext>(builder =>
+                    builder.UseInlineHandler(context =>
+                    {
+                        context.SkipRequest();
+
+                        return default;
+                    }));
+            });
+
+            // Act and assert
+            var exception = await Assert.ThrowsAsync<InvalidOperationException>(delegate
+            {
+                return client.GetAsync("/signout");
+            });
+
+            Assert.Equal("An OpenID Connect response cannot be returned from this endpoint.", exception.Message);
+        }
+
+        [Theory]
+        [InlineData("custom_error", null, null)]
+        [InlineData("custom_error", "custom_description", null)]
+        [InlineData("custom_error", "custom_description", "custom_uri")]
+        [InlineData(null, "custom_description", null)]
+        [InlineData(null, "custom_description", "custom_uri")]
+        [InlineData(null, null, "custom_uri")]
+        [InlineData(null, null, null)]
+        public async Task ProcessSignOut_AllowsRejectingRequest(string error, string description, string uri)
+        {
+            // Arrange
+            var client = CreateClient(options =>
+            {
+                options.EnableDegradedMode();
+
+                options.AddEventHandler<ProcessSignOutContext>(builder =>
+                    builder.UseInlineHandler(context =>
+                    {
+                        context.Reject(error, description, uri);
+
+                        return default;
+                    }));
+            });
+
+            // Act
+            var response = await client.PostAsync("/connect/logout", new OpenIddictRequest());
+
+            // Assert
+            Assert.Equal(error ?? Errors.InvalidRequest, response.Error);
+            Assert.Equal(description, response.ErrorDescription);
+            Assert.Equal(uri, response.ErrorUri);
+        }
+
+        [Fact]
+        public async Task ProcessSignOut_AllowsHandlingResponse()
+        {
+            // Arrange
+            var client = CreateClient(options =>
+            {
+                options.EnableDegradedMode();
+
+                options.AddEventHandler<ProcessSignOutContext>(builder =>
+                    builder.UseInlineHandler(context =>
+                    {
+                        context.Transaction.SetProperty("custom_response", new
+                        {
+                            name = "Bob le Bricoleur"
+                        });
+
+                        context.HandleRequest();
+
+                        return default;
+                    }));
+            });
+
+            // Act
+            var response = await client.PostAsync("/connect/logout", new OpenIddictRequest());
+
+            // Assert
+            Assert.Equal("Bob le Bricoleur", (string) response["name"]);
+        }
+
         protected virtual void ConfigureServices(IServiceCollection services)
         {
             services.AddOpenIddict()