Support relative redirect_uri/post_logout_redirect_uri in the client stack and revisit how OpenIddict handles URIs

gen/OpenIddict.Client.WebIntegration.Generators/OpenIddictClientWebIntegrationGenerator.cs

@@ -184,11 +184,6 @@ public sealed partial class OpenIddictClientWebIntegrationBuilder
                 throw new ArgumentNullException(nameof(address));
             }
 
-            if (!address.IsAbsoluteUri || !address.IsWellFormedOriginalString())
-            {
-                throw new ArgumentException(SR.GetResourceString(SR.ID0144), nameof(address));
-            }
-
             return Configure(options => options.RedirectUri = address);
         }
 
@@ -204,12 +199,7 @@ public sealed partial class OpenIddictClientWebIntegrationBuilder
                 throw new ArgumentException(SR.GetResourceString(SR.ID0143), nameof(address));
             }
 
-            if (!Uri.TryCreate(address, UriKind.Absolute, out Uri? uri))
-            {
-                throw new ArgumentException(SR.GetResourceString(SR.ID0144), nameof(address));
-            }
-
-            return SetRedirectUri(uri);
+            return SetRedirectUri(new Uri(address, UriKind.RelativeOrAbsolute));
         }
 
         /// <summary>
@@ -285,12 +275,7 @@ public sealed partial class OpenIddictClientWebIntegrationBuilder
                 throw new ArgumentException(SR.GetResourceString(SR.ID0143), nameof({{ setting.parameter_name }}));
             }
 
-            if (!Uri.TryCreate({{ setting.parameter_name }}, UriKind.Absolute, out Uri? uri))
-            {
-                throw new ArgumentException(SR.GetResourceString(SR.ID0144), nameof({{ setting.parameter_name }}));
-            }
-
-            return Set{{ setting.property_name }}(uri);
+            return Set{{ setting.property_name }}(new Uri({{ setting.parameter_name }}, UriKind.RelativeOrAbsolute));
         }
         {{~ else ~}}
         /// <summary>

sandbox/OpenIddict.Sandbox.AspNet.Client/Startup.cs

@@ -73,14 +73,13 @@ namespace OpenIddict.Sandbox.AspNet.Client
                     // parameter containing their URL as part of authorization responses. For more information,
                     // see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.4.
                     options.SetRedirectionEndpointUris(
-                        "/callback/login/local",
-                        "/callback/login/github",
-                        "/callback/login/google",
-                        "/callback/login/twitter");
+                        "callback/login/local",
+                        "callback/login/github",
+                        "callback/login/google",
+                        "callback/login/twitter");
 
-                    // Enable the post-logout redirection endpoints needed to handle the callback stage.
-                    options.SetPostLogoutRedirectionEndpointUris(
-                        "/callback/logout/local");
+                    // Enable the post-logout redirection endpoint needed to handle the callback stage.
+                    options.SetPostLogoutRedirectionEndpointUris("callback/logout/local");
 
                     // Note: this sample uses the authorization code and refresh token
                     // flows, but you can enable the other flows if necessary.
@@ -106,15 +105,15 @@ namespace OpenIddict.Sandbox.AspNet.Client
                     // Add a client registration matching the client application definition in the server project.
                     options.AddRegistration(new OpenIddictClientRegistration
                     {
-                        ProviderName = "Local",
                         Issuer = new Uri("https://localhost:44349/", UriKind.Absolute),
+                        ProviderName = "Local",
 
                         ClientId = "mvc",
                         ClientSecret = "901564A5-E7FE-42CB-B10D-61EF6A8F3654",
                         Scopes = { Scopes.Email, Scopes.Profile, Scopes.OfflineAccess, "demo_api" },
 
-                        RedirectUri = new Uri("https://localhost:44378/callback/login/local", UriKind.Absolute),
-                        PostLogoutRedirectUri = new Uri("https://localhost:44378/callback/logout/local", UriKind.Absolute)
+                        RedirectUri = new Uri("callback/login/local", UriKind.Relative),
+                        PostLogoutRedirectUri = new Uri("callback/logout/local", UriKind.Relative)
                     });
 
                     // Register the Web providers integrations.
@@ -123,13 +122,13 @@ namespace OpenIddict.Sandbox.AspNet.Client
                            {
                                options.SetClientId("c4ade52327b01ddacff3")
                                       .SetClientSecret("da6bed851b75e317bf6b2cb67013679d9467c122")
-                                      .SetRedirectUri("https://localhost:44378/callback/login/github");
+                                      .SetRedirectUri("callback/login/github");
                            })
                            .UseGoogle(options =>
                            {
                                options.SetClientId("1016114395689-kgtgq2p6dj27d7v6e2kjkoj54dgrrckh.apps.googleusercontent.com")
                                       .SetClientSecret("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")
-                                      .SetRedirectUri("https://localhost:44378/callback/login/google")
+                                      .SetRedirectUri("callback/login/google")
                                       .SetAccessType("offline")
                                       .AddScopes(Scopes.Profile);
                            })
@@ -137,7 +136,7 @@ namespace OpenIddict.Sandbox.AspNet.Client
                            {
                                options.SetClientId("bXgwc0U3N3A3YWNuaWVsdlRmRWE6MTpjaQ")
                                       .SetClientSecret("VcohOgBp-6yQCurngo4GAyKeZh0D6SUCCSjJgEo1uRzJarjIUS")
-                                      .SetRedirectUri("https://localhost:44378/callback/login/twitter");
+                                      .SetRedirectUri("callback/login/twitter");
                            });
                 });
 

sandbox/OpenIddict.Sandbox.AspNet.Server/Startup.cs

@@ -157,7 +157,7 @@ namespace OpenIddict.Sandbox.AspNet.Server
                     // address per provider, unless all the registered providers support returning an "iss"
                     // parameter containing their URL as part of authorization responses. For more information,
                     // see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.4.
-                    options.SetRedirectionEndpointUris("/callback/login/github");
+                    options.SetRedirectionEndpointUris("callback/login/github");
 
                     // Note: this sample uses the code flow, but you can enable the other flows if necessary.
                     options.AllowAuthorizationCodeFlow();
@@ -183,7 +183,7 @@ namespace OpenIddict.Sandbox.AspNet.Server
                            {
                                options.SetClientId("c4ade52327b01ddacff3")
                                       .SetClientSecret("da6bed851b75e317bf6b2cb67013679d9467c122")
-                                      .SetRedirectUri("https://localhost:44349/callback/login/github");
+                                      .SetRedirectUri("callback/login/github");
                            });
                 })
 
@@ -192,13 +192,13 @@ namespace OpenIddict.Sandbox.AspNet.Server
                 {
                     // Enable the authorization, device, introspection,
                     // logout, token, userinfo and verification endpoints.
-                    options.SetAuthorizationEndpointUris("/connect/authorize")
-                           .SetDeviceEndpointUris("/connect/device")
-                           .SetIntrospectionEndpointUris("/connect/introspect")
-                           .SetLogoutEndpointUris("/connect/logout")
-                           .SetTokenEndpointUris("/connect/token")
-                           .SetUserinfoEndpointUris("/connect/userinfo")
-                           .SetVerificationEndpointUris("/connect/verify");
+                    options.SetAuthorizationEndpointUris("connect/authorize")
+                           .SetDeviceEndpointUris("connect/device")
+                           .SetIntrospectionEndpointUris("connect/introspect")
+                           .SetLogoutEndpointUris("connect/logout")
+                           .SetTokenEndpointUris("connect/token")
+                           .SetUserinfoEndpointUris("connect/userinfo")
+                           .SetVerificationEndpointUris("connect/verify");
 
                     // Note: this sample uses the code, device code, password and refresh token flows, but you
                     // can enable the other flows if you need to support implicit or client credentials.

sandbox/OpenIddict.Sandbox.AspNetCore.Client/Startup.cs

@@ -81,15 +81,14 @@ public class Startup
                 // parameter containing their URL as part of authorization responses. For more information,
                 // see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.4.
                 options.SetRedirectionEndpointUris(
-                    "/callback/login/local",
-                    "/callback/login/github",
-                    "/callback/login/google",
-                    "/callback/login/reddit",
-                    "/callback/login/twitter");
+                    "callback/login/local",
+                    "callback/login/github",
+                    "callback/login/google",
+                    "callback/login/reddit",
+                    "callback/login/twitter");
 
-                // Enable the post-logout redirection endpoints needed to handle the callback stage.
-                options.SetPostLogoutRedirectionEndpointUris(
-                    "/callback/logout/local");
+                // Enable the post-logout redirection endpoint needed to handle the callback stage.
+                options.SetPostLogoutRedirectionEndpointUris("callback/logout/local");
 
                 // Note: this sample uses the authorization code and refresh token
                 // flows, but you can enable the other flows if necessary.
@@ -116,15 +115,15 @@ public class Startup
                 // Add a client registration matching the client application definition in the server project.
                 options.AddRegistration(new OpenIddictClientRegistration
                 {
-                    ProviderName = "Local",
                     Issuer = new Uri("https://localhost:44395/", UriKind.Absolute),
+                    ProviderName = "Local",
 
                     ClientId = "mvc",
                     ClientSecret = "901564A5-E7FE-42CB-B10D-61EF6A8F3654",
                     Scopes = { Scopes.Email, Scopes.Profile, Scopes.OfflineAccess, "demo_api" },
 
-                    RedirectUri = new Uri("https://localhost:44381/callback/login/local", UriKind.Absolute),
-                    PostLogoutRedirectUri = new Uri("https://localhost:44381/callback/logout/local", UriKind.Absolute)
+                    RedirectUri = new Uri("callback/login/local", UriKind.Relative),
+                    PostLogoutRedirectUri = new Uri("callback/logout/local", UriKind.Relative)
                 });
 
                 // Register the Web providers integrations.
@@ -133,13 +132,13 @@ public class Startup
                        {
                            options.SetClientId("c4ade52327b01ddacff3")
                                   .SetClientSecret("da6bed851b75e317bf6b2cb67013679d9467c122")
-                                  .SetRedirectUri("https://localhost:44381/callback/login/github");
+                                  .SetRedirectUri("callback/login/github");
                        })
                        .UseGoogle(options =>
                        {
                            options.SetClientId("1016114395689-kgtgq2p6dj27d7v6e2kjkoj54dgrrckh.apps.googleusercontent.com")
                                   .SetClientSecret("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")
-                                  .SetRedirectUri("https://localhost:44381/callback/login/google")
+                                  .SetRedirectUri("callback/login/google")
                                   .SetAccessType("offline")
                                   .AddScopes(Scopes.Profile);
                        })
@@ -147,14 +146,14 @@ public class Startup
                        {
                            options.SetClientId("vDLNqhrkwrvqHgnoBWF3og")
                                   .SetClientSecret("Tpab28Dz0upyZLqn7AN3GFD1O-zaAw")
-                                  .SetRedirectUri("https://localhost:44381/callback/login/reddit")
+                                  .SetRedirectUri("callback/login/reddit")
                                   .SetDuration("permanent");
                        })
                        .UseTwitter(options =>
                        {
                            options.SetClientId("bXgwc0U3N3A3YWNuaWVsdlRmRWE6MTpjaQ")
                                   .SetClientSecret("VcohOgBp-6yQCurngo4GAyKeZh0D6SUCCSjJgEo1uRzJarjIUS")
-                                  .SetRedirectUri("https://localhost:44381/callback/login/twitter")
+                                  .SetRedirectUri("callback/login/twitter")
                                   .AddScopes("offline.access");
                        });
             });

sandbox/OpenIddict.Sandbox.AspNetCore.Server/Startup.cs

@@ -74,7 +74,7 @@ public class Startup
                 // address per provider, unless all the registered providers support returning an "iss"
                 // parameter containing their URL as part of authorization responses. For more information,
                 // see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.4.
-                options.SetRedirectionEndpointUris("/callback/login/github");
+                options.SetRedirectionEndpointUris("callback/login/github");
 
                 // Note: this sample uses the code flow, but you can enable the other flows if necessary.
                 options.AllowAuthorizationCodeFlow();
@@ -101,7 +101,7 @@ public class Startup
                        {
                            options.SetClientId("c4ade52327b01ddacff3")
                                   .SetClientSecret("da6bed851b75e317bf6b2cb67013679d9467c122")
-                                  .SetRedirectUri("https://localhost:44395/callback/login/github");
+                                  .SetRedirectUri("callback/login/github");
                        });
             })
 
@@ -110,13 +110,13 @@ public class Startup
             {
                 // Enable the authorization, device, introspection,
                 // logout, token, userinfo and verification endpoints.
-                options.SetAuthorizationEndpointUris("/connect/authorize")
-                       .SetDeviceEndpointUris("/connect/device")
-                       .SetIntrospectionEndpointUris("/connect/introspect")
-                       .SetLogoutEndpointUris("/connect/logout")
-                       .SetTokenEndpointUris("/connect/token")
-                       .SetUserinfoEndpointUris("/connect/userinfo")
-                       .SetVerificationEndpointUris("/connect/verify");
+                options.SetAuthorizationEndpointUris("connect/authorize")
+                       .SetDeviceEndpointUris("connect/device")
+                       .SetIntrospectionEndpointUris("connect/introspect")
+                       .SetLogoutEndpointUris("connect/logout")
+                       .SetTokenEndpointUris("connect/token")
+                       .SetUserinfoEndpointUris("connect/userinfo")
+                       .SetVerificationEndpointUris("connect/verify");
 
                 // Note: this sample uses the code, device code, password and refresh token flows, but you
                 // can enable the other flows if you need to support implicit or client credentials.

shared/OpenIddict.Extensions/Helpers/OpenIddictHelpers.cs

@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Security.Claims;
 using System.Security.Cryptography;
@@ -91,6 +92,83 @@ internal static class OpenIddictHelpers
         => new(source ?? throw new ArgumentNullException(nameof(source)), comparer);
 #endif
 
+    /// <summary>
+    /// Computes an absolute URI from the specified <paramref name="left"/> and <paramref name="right"/> URIs.
+    /// Note: if the <paramref name="right"/> URI is already absolute, it is directly returned.
+    /// </summary>
+    /// <param name="left">The left part.</param>
+    /// <param name="right">The right part.</param>
+    /// <returns>An absolute URI from the specified <paramref name="left"/> and <paramref name="right"/>.</returns>
+    /// <exception cref="InvalidOperationException"><paramref name="left"/> is not an absolute URI.</exception>
+    [return: NotNullIfNotNull(nameof(right))]
+    public static Uri? CreateAbsoluteUri(Uri? left, Uri? right)
+    {
+        if (right is null)
+        {
+            return null;
+        }
+
+        if (right.IsAbsoluteUri)
+        {
+            return right;
+        }
+
+        if (left is not { IsAbsoluteUri: true })
+        {
+            throw new ArgumentException(SR.GetResourceString(SR.ID0144), nameof(left));
+        }
+
+        // Ensure the left part ends with a trailing slash, as it is necessary
+        // for Uri's constructor to include the last path segment in the base URI.
+        left = left.AbsolutePath switch
+        {
+            null or { Length: 0 } => new UriBuilder(left) { Path = "/" }.Uri,
+            [.., not '/'] => new UriBuilder(left) { Path = left.AbsolutePath + "/" }.Uri,
+            ['/'] or _ => left
+        };
+
+        return new Uri(left, right);
+    }
+
+    /// <summary>
+    /// Determines whether the <paramref name="left"/> URI is a base of the <paramref name="right"/> URI.
+    /// </summary>
+    /// <param name="left">The left part.</param>
+    /// <param name="right">The right part.</param>
+    /// <returns><see langword="true"/> if <paramref name="left"/> is base of
+    /// <paramref name="right"/>, <see langword="false"/> otherwise.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="left"/> or
+    /// <paramref name="right"/> is <see langword="null"/>.</exception>
+    /// <exception cref="InvalidOperationException"><paramref name="left"/> is not an absolute URI.</exception>
+    public static bool IsBaseOf(Uri left, Uri right)
+    {
+        if (left is null)
+        {
+            throw new ArgumentNullException(nameof(left));
+        }
+
+        if (right is null)
+        {
+            throw new ArgumentNullException(nameof(right));
+        }
+
+        if (left is not { IsAbsoluteUri: true })
+        {
+            throw new ArgumentException(SR.GetResourceString(SR.ID0144), nameof(left));
+        }
+
+        // Ensure the left part ends with a trailing slash, as it is necessary
+        // for Uri's constructor to include the last path segment in the base URI.
+        left = left.AbsolutePath switch
+        {
+            null or { Length: 0 } => new UriBuilder(left) { Path = "/" }.Uri,
+            [.., not '/'] => new UriBuilder(left) { Path = left.AbsolutePath + "/" }.Uri,
+            ['/'] or _ => left
+        };
+
+        return left.IsBaseOf(right);
+    }
+
     /// <summary>
     /// Adds a query string parameter to the specified <see cref="Uri"/>.
     /// </summary>

src/OpenIddict.Abstractions/OpenIddictResources.resx

@@ -547,7 +547,7 @@ To register the server services, use 'services.AddOpenIddict().AddServer()'.</va
     <value>The issuer cannot be null or empty.</value>
   </data>
   <data name="ID0127" xml:space="preserve">
-    <value>The issuer must be a valid absolute URL.</value>
+    <value>The base URI or request URI cannot be retrieved from the request context or are now valid absolute URIs.</value>
   </data>
   <data name="ID0128" xml:space="preserve">
     <value>An OAuth 2.0/OpenID Connect server configuration or an issuer address must be registered.

src/OpenIddict.Client.AspNetCore/OpenIddictClientAspNetCoreHandlers.cs

@@ -13,7 +13,7 @@ using System.Text;
 using System.Text.Json;
 using Microsoft.AspNetCore;
 using Microsoft.AspNetCore.Diagnostics;
-using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
@@ -33,14 +33,14 @@ public static partial class OpenIddictClientAspNetCoreHandlers
         /*
          * Top-level request processing:
          */
-        InferEndpointType.Descriptor,
+        ResolveRequestUri.Descriptor,
         ValidateTransportSecurityRequirement.Descriptor,
+        ValidateHostHeader.Descriptor,
 
         /*
          * Authentication processing:
          */
         ResolveRequestForgeryProtection.Descriptor,
-        ValidateEndpointUri.Descriptor,
 
         /*
          * Challenge processing:
@@ -59,10 +59,10 @@ public static partial class OpenIddictClientAspNetCoreHandlers
         .AddRange(Session.DefaultHandlers);
 
     /// <summary>
-    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// Contains the logic responsible for resolving the request URI from the ASP.NET Core environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
     /// </summary>
-    public sealed class InferEndpointType : IOpenIddictClientHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictClientHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -70,8 +70,9 @@ public static partial class OpenIddictClientAspNetCoreHandlers
         public static OpenIddictClientHandlerDescriptor Descriptor { get; }
             = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireHttpRequest>()
-                .UseSingletonHandler<InferEndpointType>()
+                .UseSingletonHandler<ResolveRequestUri>()
                 .SetOrder(int.MinValue + 50_000)
+                .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
 
         /// <inheritdoc/>
@@ -87,63 +88,37 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            context.EndpointType =
-                Matches(request, context.Options.PostLogoutRedirectionEndpointUris) ? OpenIddictClientEndpointType.PostLogoutRedirection :
-                Matches(request, context.Options.RedirectionEndpointUris)           ? OpenIddictClientEndpointType.Redirection :
-                                                                                      OpenIddictClientEndpointType.Unknown;
-
-            return default;
-
-            static bool Matches(HttpRequest request, IReadOnlyList<Uri> addresses)
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
+
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                for (var index = 0; index < addresses.Count; index++)
-                {
-                    var address = addresses[index];
-                    if (address.IsAbsoluteUri)
-                    {
-                        // If the request host is not available (e.g because HTTP/1.0 was used), ignore absolute URLs.
-                        if (!request.Host.HasValue)
-                        {
-                            continue;
-                        }
-
-                        // Create a Uri instance using the request scheme and raw host and compare the two base addresses.
-                        if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host, UriKind.Absolute, out Uri? uri) ||
-                            !uri.IsWellFormedOriginalString() || uri.Port != address.Port ||
-                            !string.Equals(uri.Scheme, address.Scheme, StringComparison.OrdinalIgnoreCase) ||
-                            !string.Equals(uri.Host, address.Host, StringComparison.OrdinalIgnoreCase))
-                        {
-                            continue;
-                        }
-
-                        var path = PathString.FromUriComponent(address);
-                        if (AreEquivalent(path, request.PathBase + request.Path))
-                        {
-                            return true;
-                        }
-                    }
+                { HasValue: true } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: new Uri(request.GetEncodedUrl(), UriKind.Absolute)),
 
-                    else if (address.OriginalString.StartsWith("/", StringComparison.OrdinalIgnoreCase))
+                { HasValue: false } => (
+                    BaseUri: new UriBuilder
                     {
-                        var path = new PathString(address.OriginalString);
-                        if (AreEquivalent(path, request.Path))
-                        {
-                            return true;
-                        }
-                    }
-                }
-
-                return false;
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
 
-                // ASP.NET Core's routing system ignores trailing slashes when determining
-                // whether the request path matches a registered route, which is not the case
-                // with PathString, that treats /connect/token and /connect/token/ as different
-                // addresses. To mitigate this inconsistency, a manual check is used here.
-                static bool AreEquivalent(PathString left, PathString right)
-                    => left.Equals(right, StringComparison.OrdinalIgnoreCase) ||
-                       left.Equals(right + "/", StringComparison.OrdinalIgnoreCase) ||
-                       right.Equals(left + "/", StringComparison.OrdinalIgnoreCase);
-            }
+            return default;
         }
     }
 
@@ -161,7 +136,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 .AddFilter<RequireHttpRequest>()
                 .AddFilter<RequireTransportSecurityRequirementEnabled>()
                 .UseSingletonHandler<ValidateTransportSecurityRequirement>()
-                .SetOrder(InferEndpointType.Descriptor.Order + 1_000)
+                .SetOrder(InferEndpointType.Descriptor.Order + 250)
                 .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
 
@@ -178,18 +153,58 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            // Don't require that the host be present if the request is not handled by OpenIddict.
-            if (context.EndpointType is OpenIddictClientEndpointType.Unknown)
+            // Don't require that transport security be used if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictClientEndpointType.Unknown && !request.IsHttps)
             {
+                context.Reject(
+                    error: Errors.InvalidRequest,
+                    description: SR.GetResourceString(SR.ID2083),
+                    uri: SR.FormatID8000(SR.ID2083));
+
                 return default;
             }
 
-            if (!request.IsHttps)
+            return default;
+        }
+    }
+
+    /// <summary>
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
+    /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
+    /// </summary>
+    public sealed class ValidateHostHeader : IOpenIddictClientHandler<ProcessRequestContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
+            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
+                .AddFilter<RequireHttpRequest>()
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(ValidateTransportSecurityRequirement.Descriptor.Order + 250)
+                .SetType(OpenIddictClientHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessRequestContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
+            // this may indicate that the request was incorrectly processed by another server stack.
+            var request = context.Transaction.GetHttpRequest() ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
+
+            // Don't require that the request host be present if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictClientEndpointType.Unknown && !request.Host.HasValue)
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2083),
-                    uri: SR.FormatID8000(SR.ID2083));
+                    description: SR.FormatID2081(HeaderNames.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
 
                 return default;
             }
@@ -401,110 +416,6 @@ public static partial class OpenIddictClientAspNetCoreHandlers
         }
     }
 
-    /// <summary>
-    /// Contains the logic responsible for comparing the current request URL to the expected URL stored in the state token.
-    /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
-    /// </summary>
-    public sealed class ValidateEndpointUri : IOpenIddictClientHandler<ProcessAuthenticationContext>
-    {
-        /// <summary>
-        /// Gets the default descriptor definition assigned to this handler.
-        /// </summary>
-        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
-            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
-                .AddFilter<RequireHttpRequest>()
-                .AddFilter<RequireStateTokenValidated>()
-                .UseSingletonHandler<ValidateEndpointUri>()
-                .SetOrder(ResolveRequestForgeryProtection.Descriptor.Order + 500)
-                .SetType(OpenIddictClientHandlerType.BuiltIn)
-                .Build();
-
-        /// <inheritdoc/>
-        public ValueTask HandleAsync(ProcessAuthenticationContext context)
-        {
-            if (context is null)
-            {
-                throw new ArgumentNullException(nameof(context));
-            }
-
-            Debug.Assert(context.StateTokenPrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
-
-            // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
-            // this may indicate that the request was incorrectly processed by another server stack.
-            var request = context.Transaction.GetHttpRequest() ??
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
-
-            // Resolve the endpoint type allowed to be used with the state token.
-            if (!Enum.TryParse(context.StateTokenPrincipal.GetClaim(Claims.Private.EndpointType),
-                ignoreCase: true, out OpenIddictClientEndpointType type))
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0340));
-            }
-
-            // Resolve the endpoint URI from either the redirect_uri or post_logout_redirect_uri
-            // depending on the type of endpoint meant to be used with the specified state token.
-            var value = type switch
-            {
-                OpenIddictClientEndpointType.PostLogoutRedirection =>
-                    context.StateTokenPrincipal.GetClaim(Claims.Private.PostLogoutRedirectUri),
-
-                OpenIddictClientEndpointType.Redirection =>
-                    context.StateTokenPrincipal.GetClaim(Claims.Private.RedirectUri),
-
-                _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0340))
-            };
-
-            // If the endpoint URI cannot be resolved, this likely means the authorization or
-            // logout request was sent without a redirect_uri/post_logout_redirect_uri attached.
-            if (string.IsNullOrEmpty(value))
-            {
-                return default;
-            }
-
-            // Compute the absolute URL of the current request without the query string.
-            var uri = new Uri(request.Scheme + Uri.SchemeDelimiter + request.Host +
-                request.PathBase + request.Path, UriKind.Absolute);
-
-            // Compare the current HTTP request address to the original endpoint URI. If the two don't
-            // match, this may indicate a mix-up attack. While the authorization server is expected to
-            // abort the authorization flow by rejecting the token request that may be eventually sent
-            // with the original endpoint URI, many servers are known to incorrectly implement this
-            // endpoint URI validation logic. This check also offers limited protection as it cannot
-            // prevent the authorization code from being leaked to a malicious authorization server.
-            // By comparing the endpoint URI directly in the client, a first layer of protection is
-            // provided independently of whether the authorization server will enforce this check.
-            //
-            // See https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-19#section-4.4.2.2
-            // for more information.
-            var address = new Uri(value, UriKind.Absolute);
-            if (uri != new UriBuilder(address) { Query = null }.Uri)
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2138),
-                    uri: SR.FormatID8000(SR.ID2138));
-
-                return default;
-            }
-
-            // Ensure all the query string parameters that were part of the original endpoint URI
-            // are present in the current request (parameters that were not part of the original
-            // endpoint URI are assumed to be authorization response parameters and are ignored).
-            if (!string.IsNullOrEmpty(address.Query) && QueryHelpers.ParseQuery(address.Query)
-                .Any(parameter => request.Query[parameter.Key] != parameter.Value))
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2138),
-                    uri: SR.FormatID8000(SR.ID2138));
-
-                return default;
-            }
-
-            return default;
-        }
-    }
-
     /// <summary>
     /// Contains the logic responsible for resolving the context-specific properties and parameters stored in the
     /// ASP.NET Core authentication properties specified by the application that triggered the challenge operation.

src/OpenIddict.Client.Owin/OpenIddictClientOwinConstants.cs

@@ -16,6 +16,7 @@ public static class OpenIddictClientOwinConstants
         public const string CacheControl = "Cache-Control";
         public const string ContentType = "Content-Type";
         public const string Expires = "Expires";
+        public const string Host = "Host";
         public const string Pragma = "Pragma";
     }
 

src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.cs

@@ -15,7 +15,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using Owin;
 using static OpenIddict.Client.Owin.OpenIddictClientOwinConstants;
 using Properties = OpenIddict.Client.Owin.OpenIddictClientOwinConstants.Properties;
@@ -29,14 +28,14 @@ public static partial class OpenIddictClientOwinHandlers
         /*
          * Top-level request processing:
          */
-        InferEndpointType.Descriptor,
+        ResolveRequestUri.Descriptor,
         ValidateTransportSecurityRequirement.Descriptor,
+        ValidateHostHeader.Descriptor,
 
         /*
          * Authentication processing:
          */
         ResolveRequestForgeryProtection.Descriptor,
-        ValidateEndpointUri.Descriptor,
 
         /*
          * Challenge processing:
@@ -55,10 +54,10 @@ public static partial class OpenIddictClientOwinHandlers
         .AddRange(Session.DefaultHandlers);
 
     /// <summary>
-    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// Contains the logic responsible for resolving the request URI from the OWIN environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
     /// </summary>
-    public sealed class InferEndpointType : IOpenIddictClientHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictClientHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -66,9 +65,7 @@ public static partial class OpenIddictClientOwinHandlers
         public static OpenIddictClientHandlerDescriptor Descriptor { get; }
             = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireOwinRequest>()
-                .UseSingletonHandler<InferEndpointType>()
-                // Note: this handler must be invoked before any other handler,
-                // including the built-in handlers defined in OpenIddict.Client.
+                .UseSingletonHandler<ResolveRequestUri>()
                 .SetOrder(int.MinValue + 50_000)
                 .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
@@ -86,63 +83,37 @@ public static partial class OpenIddictClientOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            context.EndpointType =
-                Matches(request, context.Options.PostLogoutRedirectionEndpointUris) ? OpenIddictClientEndpointType.PostLogoutRedirection :
-                Matches(request, context.Options.RedirectionEndpointUris)           ? OpenIddictClientEndpointType.Redirection :
-                                                                                      OpenIddictClientEndpointType.Unknown;
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
 
-            return default;
-
-            static bool Matches(IOwinRequest request, IReadOnlyList<Uri> addresses)
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                for (var index = 0; index < addresses.Count; index++)
-                {
-                    var address = addresses[index];
-                    if (address.IsAbsoluteUri)
-                    {
-                        // If the request host is not available (e.g because HTTP/1.0 was used), ignore absolute URLs.
-                        if (string.IsNullOrEmpty(request.Host.Value))
-                        {
-                            continue;
-                        }
-
-                        // Create a Uri instance using the request scheme and raw host and compare the two base addresses.
-                        if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host, UriKind.Absolute, out Uri? uri) ||
-                            !uri.IsWellFormedOriginalString() || uri.Port != address.Port ||
-                            !string.Equals(uri.Scheme, address.Scheme, StringComparison.OrdinalIgnoreCase) ||
-                            !string.Equals(uri.Host, address.Host, StringComparison.OrdinalIgnoreCase))
-                        {
-                            continue;
-                        }
-
-                        var path = PathString.FromUriComponent(address);
-                        if (AreEquivalent(path, request.PathBase + request.Path))
-                        {
-                            return true;
-                        }
-                    }
+                { Value.Length: > 0 } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: request.Uri),
 
-                    else if (address.OriginalString.StartsWith("/", StringComparison.OrdinalIgnoreCase))
+                { Value: null or { Length: 0 } } => (
+                    BaseUri: new UriBuilder
                     {
-                        var path = new PathString(address.OriginalString);
-                        if (AreEquivalent(path, request.Path))
-                        {
-                            return true;
-                        }
-                    }
-                }
-
-                return false;
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
 
-                // ASP.NET MVC's routing system ignores trailing slashes when determining
-                // whether the request path matches a registered route, which is not the case
-                // with PathString, that treats /connect/token and /connect/token/ as different
-                // addresses. To mitigate this inconsistency, a manual check is used here.
-                static bool AreEquivalent(PathString left, PathString right)
-                    => left.Equals(right, StringComparison.OrdinalIgnoreCase) ||
-                       left.Equals(right + new PathString("/"), StringComparison.OrdinalIgnoreCase) ||
-                       right.Equals(left + new PathString("/"), StringComparison.OrdinalIgnoreCase);
-            }
+            return default;
         }
     }
 
@@ -160,7 +131,7 @@ public static partial class OpenIddictClientOwinHandlers
                 .AddFilter<RequireOwinRequest>()
                 .AddFilter<RequireTransportSecurityRequirementEnabled>()
                 .UseSingletonHandler<ValidateTransportSecurityRequirement>()
-                .SetOrder(InferEndpointType.Descriptor.Order + 1_000)
+                .SetOrder(InferEndpointType.Descriptor.Order + 250)
                 .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
 
@@ -177,7 +148,7 @@ public static partial class OpenIddictClientOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            // Don't require that the host be present if the request is not handled by OpenIddict.
+            // Don't require that transport security be used if the request is not handled by OpenIddict.
             if (context.EndpointType is OpenIddictClientEndpointType.Unknown)
             {
                 return default;
@@ -197,6 +168,52 @@ public static partial class OpenIddictClientOwinHandlers
         }
     }
 
+    /// <summary>
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
+    /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
+    /// </summary>
+    public sealed class ValidateHostHeader : IOpenIddictClientHandler<ProcessRequestContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
+            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
+                .AddFilter<RequireOwinRequest>()
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(InferEndpointType.Descriptor.Order + 500)
+                .SetType(OpenIddictClientHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessRequestContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
+            // this may indicate that the request was incorrectly processed by another server stack.
+            var request = context.Transaction.GetOwinRequest() ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
+
+            // Don't require that the request host be present if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictClientEndpointType.Unknown &&
+                string.IsNullOrEmpty(request.Host.Value))
+            {
+                context.Reject(
+                    error: Errors.InvalidRequest,
+                    description: SR.FormatID2081(Headers.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
+
+                return default;
+            }
+
+            return default;
+        }
+    }
+
     /// <summary>
     /// Contains the logic responsible for extracting OpenID Connect requests from GET or POST HTTP requests.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
@@ -409,113 +426,6 @@ public static partial class OpenIddictClientOwinHandlers
         }
     }
 
-    /// <summary>
-    /// Contains the logic responsible for comparing the current request URL to the expected URL stored in the state token.
-    /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
-    /// </summary>
-    public sealed class ValidateEndpointUri : IOpenIddictClientHandler<ProcessAuthenticationContext>
-    {
-        /// <summary>
-        /// Gets the default descriptor definition assigned to this handler.
-        /// </summary>
-        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
-            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
-                .AddFilter<RequireOwinRequest>()
-                .AddFilter<RequireStateTokenValidated>()
-                .UseSingletonHandler<ValidateEndpointUri>()
-                .SetOrder(ResolveRequestForgeryProtection.Descriptor.Order + 500)
-                .SetType(OpenIddictClientHandlerType.BuiltIn)
-                .Build();
-
-        /// <inheritdoc/>
-        public ValueTask HandleAsync(ProcessAuthenticationContext context)
-        {
-            if (context is null)
-            {
-                throw new ArgumentNullException(nameof(context));
-            }
-
-            Debug.Assert(context.StateTokenPrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
-
-            // This handler only applies to OWIN requests. If the HTTP context cannot be resolved,
-            // this may indicate that the request was incorrectly processed by another server stack.
-            var request = context.Transaction.GetOwinRequest() ??
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
-
-            // Resolve the endpoint type allowed to be used with the state token.
-            if (!Enum.TryParse(context.StateTokenPrincipal.GetClaim(Claims.Private.EndpointType),
-                ignoreCase: true, out OpenIddictClientEndpointType type))
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0340));
-            }
-
-            // Resolve the endpoint address from either the redirect_uri or post_logout_redirect_uri
-            // depending on the type of endpoint allowed to receive the specified state token.
-            var value = type switch
-            {
-                OpenIddictClientEndpointType.PostLogoutRedirection =>
-                    context.StateTokenPrincipal.GetClaim(Claims.Private.PostLogoutRedirectUri),
-
-                OpenIddictClientEndpointType.Redirection =>
-                    context.StateTokenPrincipal.GetClaim(Claims.Private.RedirectUri),
-
-                _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0340))
-            };
-
-            // If the endpoint URI cannot be resolved, this likely means the authorization or
-            // logout request was sent without a redirect_uri/post_logout_redirect_uri attached.
-            if (string.IsNullOrEmpty(value))
-            {
-                return default;
-            }
-
-            // Compute the absolute URL of the current request without the query string.
-            var uri = new Uri(request.Scheme + Uri.SchemeDelimiter + request.Host +
-                request.PathBase + request.Path, UriKind.Absolute);
-
-            // Compare the current HTTP request address to the original endpoint URI. If the two don't
-            // match, this may indicate a mix-up attack. While the authorization server is expected to
-            // abort the authorization flow by rejecting the token request that may be eventually sent
-            // with the original endpoint URI, many servers are known to incorrectly implement this
-            // endpoint URI validation logic. This check also offers limited protection as it cannot
-            // prevent the authorization code from being leaked to a malicious authorization server.
-            // By comparing the endpoint URI directly in the client, a first layer of protection is
-            // provided independently of whether the authorization server will enforce this check.
-            //
-            // See https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-19#section-4.4.2.2
-            // for more information.
-            var address = new Uri(value, UriKind.Absolute);
-            if (uri != new UriBuilder(address) { Query = null }.Uri)
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2138),
-                    uri: SR.FormatID8000(SR.ID2138));
-
-                return default;
-            }
-
-            // Ensure all the query string parameters that were part of the original endpoint URI
-            // are present in the current request (parameters that were not part of the original
-            // endpoint URI are assumed to be authorization response parameters and are ignored).
-            if (!string.IsNullOrEmpty(address.Query) && OpenIddictHelpers.ParseQuery(address.Query)
-                // Note: ignore parameters that only include empty values
-                // to match the logic used by OWIN for IOwinRequest.Query.
-                .Where(parameter => parameter.Value.Any(value => !string.IsNullOrEmpty(value)))
-                .Any(parameter => request.Query[parameter.Key] != parameter.Value))
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2138),
-                    uri: SR.FormatID8000(SR.ID2138));
-
-                return default;
-            }
-
-            return default;
-        }
-    }
-
     /// <summary>
     /// Contains the logic responsible for resolving the context-specific properties and parameters stored in the
     /// OWIN authentication properties specified by the application that triggered the challenge operation.

src/OpenIddict.Client.SystemNetHttp/OpenIddictClientSystemNetHttpHandlers.Exchange.cs

@@ -53,7 +53,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                     .Build();
 
             /// <inheritdoc/>
-            public async ValueTask HandleAsync(PrepareTokenRequestContext context)
+            public ValueTask HandleAsync(PrepareTokenRequestContext context)
             {
                 if (context is null)
                 {
@@ -70,16 +70,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 // If no client identifier was attached to the request, skip the following logic.
                 if (string.IsNullOrEmpty(context.Request.ClientId))
                 {
-                    return;
-                }
-
-                var configuration = await context.Registration.ConfigurationManager.GetConfigurationAsync(default) ??
-                    throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-                // Ensure the issuer resolved from the configuration matches the expected value.
-                if (configuration.Issuer != context.Issuer)
-                {
-                    throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
+                    return default;
                 }
 
                 // The OAuth 2.0 specification recommends sending the client credentials using basic authentication.
@@ -93,7 +84,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 //
                 // See https://tools.ietf.org/html/rfc8414#section-2
                 // and https://tools.ietf.org/html/rfc6749#section-2.3.1 for more information.
-                if (!configuration.TokenEndpointAuthMethodsSupported.Contains(ClientAuthenticationMethods.ClientSecretPost))
+                if (!context.Configuration.TokenEndpointAuthMethodsSupported.Contains(ClientAuthenticationMethods.ClientSecretPost))
                 {
                     // Important: the credentials MUST be formURL-encoded before being base64-encoded.
                     var credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes(new StringBuilder()
@@ -109,6 +100,8 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                     context.Request.ClientId = context.Request.ClientSecret = null;
                 }
 
+                return default;
+
                 static string? EscapeDataString(string? value)
                     => value is not null ? Uri.EscapeDataString(value).Replace("%20", "+") : null;
             }

src/OpenIddict.Client/OpenIddictClientBuilder.cs

@@ -1126,6 +1126,22 @@ public sealed class OpenIddictClientBuilder
     public OpenIddictClientBuilder SetStateTokenLifetime(TimeSpan? lifetime)
         => Configure(options => options.StateTokenLifetime = lifetime);
 
+    /// <summary>
+    /// Sets the client URI, which is used as the value for the "issuer" claim.
+    /// </summary>
+    /// <param name="address">The client URI.</param>
+    /// <returns>The <see cref="OpenIddictClientBuilder"/> instance.</returns>
+    [EditorBrowsable(EditorBrowsableState.Advanced)]
+    public OpenIddictClientBuilder SetClientUri(Uri address)
+    {
+        if (address is null)
+        {
+            throw new ArgumentNullException(nameof(address));
+        }
+
+        return Configure(options => options.ClientUri = address);
+    }
+
     /// <inheritdoc/>
     [EditorBrowsable(EditorBrowsableState.Never)]
     public override bool Equals(object? obj) => base.Equals(obj);

src/OpenIddict.Client/OpenIddictClientConfiguration.cs

@@ -70,23 +70,9 @@ public sealed class OpenIddictClientConfiguration : IPostConfigureOptions<OpenId
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID0313));
                     }
 
-                    registration.MetadataAddress ??= new Uri(".well-known/openid-configuration", UriKind.Relative);
-
-                    if (!registration.MetadataAddress.IsAbsoluteUri)
-                    {
-                        var issuer = registration.Issuer;
-                        if (!issuer.OriginalString.EndsWith("/", StringComparison.Ordinal))
-                        {
-                            issuer = new Uri(issuer.OriginalString + "/", UriKind.Absolute);
-                        }
-
-                        if (registration.MetadataAddress.OriginalString.StartsWith("/", StringComparison.Ordinal))
-                        {
-                            registration.MetadataAddress = new Uri(registration.MetadataAddress.OriginalString[1..], UriKind.Relative);
-                        }
-
-                        registration.MetadataAddress = new Uri(issuer, registration.MetadataAddress);
-                    }
+                    registration.MetadataAddress = OpenIddictHelpers.CreateAbsoluteUri(
+                        registration.Issuer,
+                        registration.MetadataAddress ?? new Uri(".well-known/openid-configuration", UriKind.Relative));
 
                     registration.ConfigurationManager = new ConfigurationManager<OpenIddictConfiguration>(
                         registration.MetadataAddress.AbsoluteUri, new OpenIddictClientRetriever(_service, registration))

src/OpenIddict.Client/OpenIddictClientEvents.cs

@@ -39,6 +39,24 @@ public static partial class OpenIddictClientEvents
             set => Transaction.EndpointType = value;
         }
 
+        /// <summary>
+        /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
+        /// </summary>
+        public Uri? RequestUri
+        {
+            get => Transaction.RequestUri;
+            set => Transaction.RequestUri = value;
+        }
+
+        /// <summary>
+        /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+        /// </summary>
+        public Uri? BaseUri
+        {
+            get => Transaction.BaseUri;
+            set => Transaction.BaseUri = value;
+        }
+
         /// <summary>
         /// Gets the logger responsible for logging processed operations.
         /// </summary>
@@ -49,15 +67,6 @@ public static partial class OpenIddictClientEvents
         /// </summary>
         public OpenIddictClientOptions Options => Transaction.Options;
 
-        /// <summary>
-        /// Gets or sets the issuer used for the current request.
-        /// </summary>
-        public Uri? Issuer
-        {
-            get => Transaction.Issuer;
-            set => Transaction.Issuer = value;
-        }
-
         /// <summary>
         /// Gets or sets the server configuration used for the current request.
         /// </summary>
@@ -299,6 +308,11 @@ public static partial class OpenIddictClientEvents
         /// </summary>
         public Dictionary<string, string?> Properties { get; } = new(StringComparer.Ordinal);
 
+        /// <summary>
+        /// Gets or sets the issuer used for the authentication demand, if applicable.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the grant type used for the authentication demand, if applicable.
         /// </summary>
@@ -714,6 +728,11 @@ public static partial class OpenIddictClientEvents
         /// </summary>
         public Dictionary<string, string?> Properties { get; } = new(StringComparer.Ordinal);
 
+        /// <summary>
+        /// Gets or sets the issuer used for the challenge demand, if applicable.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the name of the provider that will be
         /// used to resolve the issuer identity, if applicable.
@@ -871,6 +890,11 @@ public static partial class OpenIddictClientEvents
         /// </summary>
         public Dictionary<string, string?> Properties { get; } = new(StringComparer.Ordinal);
 
+        /// <summary>
+        /// Gets or sets the issuer used for the sign-out demand, if applicable.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the name of the provider that will be
         /// used to resolve the issuer identity, if applicable.

src/OpenIddict.Client/OpenIddictClientHandlers.Discovery.cs

@@ -225,7 +225,8 @@ public static partial class OpenIddictClientHandlers
                     return default;
                 }
 
-                if (context.Issuer is not null && context.Issuer != address)
+                // Ensure the issuer matches the expected value.
+                if (address != context.Registration.Issuer)
                 {
                     context.Reject(
                         error: Errors.ServerError,

src/OpenIddict.Client/OpenIddictClientHandlers.Protection.cs

@@ -83,7 +83,7 @@ public static partial class OpenIddictClientHandlers
                 {
                     // When only state tokens are considered valid, use the token validation parameters of the client.
                     1 when context.ValidTokenTypes.Contains(TokenTypeHints.StateToken)
-                        => GetClientTokenValidationParameters(context.Options),
+                        => GetClientTokenValidationParameters(context.BaseUri, context.Options),
 
                     // Otherwise, use the token validation parameters of the authorization server.
                     _ => GetServerTokenValidationParameters(context.Registration, context.Configuration)
@@ -94,10 +94,27 @@ public static partial class OpenIddictClientHandlers
 
                 return default;
 
-                static TokenValidationParameters GetClientTokenValidationParameters(OpenIddictClientOptions options)
+                static TokenValidationParameters GetClientTokenValidationParameters(Uri? address, OpenIddictClientOptions options)
                 {
                     var parameters = options.TokenValidationParameters.Clone();
-                    parameters.ValidateIssuer = false;
+
+                    parameters.ValidIssuers ??= (options.ClientUri ?? address) switch
+                    {
+                        null => null,
+
+                        // If the client URI doesn't contain any path/query/fragment, allow both http://www.fabrikam.com
+                        // and http://www.fabrikam.com/ (the recommended URI representation) to be considered valid.
+                        // See https://datatracker.ietf.org/doc/html/rfc3986#section-6.2.3 for more information.
+                        { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } uri => new[]
+                        {
+                            uri.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
+                            uri.AbsoluteUri[..^1]
+                        },
+
+                        Uri uri => new[] { uri.AbsoluteUri }
+                    };
+
+                    parameters.ValidateIssuer = parameters.ValidIssuers is not null;
 
                     // For state tokens, only the short "oi_stet+jwt" form is valid.
                     parameters.ValidTypes = new[] { JsonWebTokenTypes.Private.StateToken };
@@ -117,13 +134,13 @@ public static partial class OpenIddictClientHandlers
                         // If the issuer URI doesn't contain any path/query/fragment, allow both http://www.fabrikam.com
                         // and http://www.fabrikam.com/ (the recommended URI representation) to be considered valid.
                         // See https://datatracker.ietf.org/doc/html/rfc3986#section-6.2.3 for more information.
-                        { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } issuer => new[]
+                        { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } uri => new[]
                         {
-                            issuer.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
-                            issuer.AbsoluteUri[..^1]
+                            uri.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
+                            uri.AbsoluteUri[..^1]
                         },
 
-                        Uri issuer => new[] { issuer.AbsoluteUri }
+                        Uri uri => new[] { uri.AbsoluteUri }
                     };
 
                     parameters.ValidateIssuer = parameters.ValidIssuers is not null;

src/OpenIddict.Client/OpenIddictClientHandlers.cs

@@ -11,6 +11,7 @@ using System.Runtime.InteropServices;
 using System.Security.Claims;
 using System.Text;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Primitives;
 using Microsoft.IdentityModel.Tokens;
 using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
@@ -21,6 +22,11 @@ namespace OpenIddict.Client;
 public static partial class OpenIddictClientHandlers
 {
     public static ImmutableArray<OpenIddictClientHandlerDescriptor> DefaultHandlers { get; } = ImmutableArray.Create(
+        /*
+         * Top-level request processing:
+         */
+        InferEndpointType.Descriptor,
+
         /*
          * Authentication processing:
          */
@@ -33,6 +39,7 @@ public static partial class OpenIddictClientHandlers
         RedeemStateTokenEntry.Descriptor,
         ValidateStateTokenEndpointType.Descriptor,
         ValidateRequestForgeryProtection.Descriptor,
+        ValidateEndpointUri.Descriptor,
         ResolveClientRegistrationFromStateToken.Descriptor,
         ValidateIssuerParameter.Descriptor,
         HandleFrontchannelErrorResponse.Descriptor,
@@ -100,9 +107,9 @@ public static partial class OpenIddictClientHandlers
         AttachScopes.Descriptor,
         AttachNonce.Descriptor,
         AttachCodeChallengeParameters.Descriptor,
-        PrepareStateTokenPrincipal.Descriptor,
+        PrepareLoginStateTokenPrincipal.Descriptor,
         ValidateRedirectUriParameter.Descriptor,
-        GenerateStateToken.Descriptor,
+        GenerateLoginStateToken.Descriptor,
         AttachChallengeParameters.Descriptor,
         AttachCustomChallengeParameters.Descriptor,
 
@@ -134,6 +141,86 @@ public static partial class OpenIddictClientHandlers
         .AddRange(Session.DefaultHandlers)
         .AddRange(Userinfo.DefaultHandlers);
 
+    /// <summary>
+    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// </summary>
+    public sealed class InferEndpointType : IOpenIddictClientHandler<ProcessRequestContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
+            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
+                .UseSingletonHandler<InferEndpointType>()
+                .SetOrder(int.MinValue + 100_000)
+                .SetType(OpenIddictClientHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessRequestContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            if (context is not { BaseUri.IsAbsoluteUri: true, RequestUri.IsAbsoluteUri: true })
+            {
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0127));
+            }
+
+            context.EndpointType =
+                Matches(context.Options.RedirectionEndpointUris)           ? OpenIddictClientEndpointType.Redirection           :
+                Matches(context.Options.PostLogoutRedirectionEndpointUris) ? OpenIddictClientEndpointType.PostLogoutRedirection :
+                                                                             OpenIddictClientEndpointType.Unknown;
+
+            return default;
+
+            bool Matches(IReadOnlyList<Uri> addresses)
+            {
+                for (var index = 0; index < addresses.Count; index++)
+                {
+                    var address = addresses[index];
+                    if (address.IsAbsoluteUri)
+                    {
+                        if (Equals(address, context.RequestUri))
+                        {
+                            return true;
+                        }
+                    }
+
+                    else
+                    {
+                        var uri = OpenIddictHelpers.CreateAbsoluteUri(context.BaseUri, address);
+                        if (uri.IsWellFormedOriginalString() &&
+                            OpenIddictHelpers.IsBaseOf(context.BaseUri, uri) && Equals(uri, context.RequestUri))
+                        {
+                            return true;
+                        }
+                    }
+                }
+
+                return false;
+            }
+
+            static bool Equals(Uri left, Uri right) =>
+                string.Equals(left.Scheme, right.Scheme, StringComparison.OrdinalIgnoreCase) &&
+                string.Equals(left.Host, right.Host, StringComparison.OrdinalIgnoreCase) &&
+                left.Port == right.Port &&
+                // Note: paths are considered equivalent even if the casing isn't identical or if one of the two
+                // paths only differs by a trailing slash, which matches the classical behavior seen on ASP.NET,
+                // Microsoft.Owin/Katana and ASP.NET Core. Developers who prefer a different behavior can remove
+                // this handler and replace it by a custom version implementing a more strict comparison logic.
+                (string.Equals(left.AbsolutePath, right.AbsolutePath, StringComparison.OrdinalIgnoreCase) ||
+                 (left.AbsolutePath.Length == right.AbsolutePath.Length + 1 &&
+                  left.AbsolutePath.StartsWith(right.AbsolutePath, StringComparison.OrdinalIgnoreCase) &&
+                  left.AbsolutePath[^1] is '/') ||
+                 (right.AbsolutePath.Length == left.AbsolutePath.Length + 1 &&
+                  right.AbsolutePath.StartsWith(left.AbsolutePath, StringComparison.OrdinalIgnoreCase) &&
+                  right.AbsolutePath[^1] is '/'));
+        }
+    }
+
     /// <summary>
     /// Contains the logic responsible for rejecting invalid authentication demands.
     /// </summary>
@@ -277,12 +364,6 @@ public static partial class OpenIddictClientHandlers
             context.Configuration ??= await context.Registration.ConfigurationManager.GetConfigurationAsync(default) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
 
-            // Ensure the issuer resolved from the configuration matches the expected value.
-            if (context.Configuration.Issuer != context.Issuer)
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
-            }
-
             // Ensure the selected grant type, if explicitly set, is listed as supported in the configuration.
             if (!string.IsNullOrEmpty(context.GrantType) &&
                 !context.Configuration.GrantTypesSupported.Contains(context.GrantType))
@@ -655,6 +736,108 @@ public static partial class OpenIddictClientHandlers
         }
     }
 
+    /// <summary>
+    /// Contains the logic responsible for comparing the current request URL to the expected URL stored in the state token.
+    /// </summary>
+    public sealed class ValidateEndpointUri : IOpenIddictClientHandler<ProcessAuthenticationContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictClientHandlerDescriptor Descriptor { get; }
+            = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
+                .AddFilter<RequireStateTokenValidated>()
+                .UseSingletonHandler<ValidateEndpointUri>()
+                .SetOrder(ValidateRequestForgeryProtection.Descriptor.Order + 1_000)
+                .SetType(OpenIddictClientHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessAuthenticationContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            Debug.Assert(context.StateTokenPrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
+
+            // Resolve the endpoint type allowed to be used with the state token.
+            if (!Enum.TryParse(context.StateTokenPrincipal.GetClaim(Claims.Private.EndpointType),
+                ignoreCase: true, out OpenIddictClientEndpointType type))
+            {
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0340));
+            }
+
+            // Resolve the endpoint URI from either the redirect_uri or post_logout_redirect_uri
+            // depending on the type of endpoint meant to be used with the specified state token.
+            var value = type switch
+            {
+                OpenIddictClientEndpointType.PostLogoutRedirection =>
+                    context.StateTokenPrincipal.GetClaim(Claims.Private.PostLogoutRedirectUri),
+
+                OpenIddictClientEndpointType.Redirection =>
+                    context.StateTokenPrincipal.GetClaim(Claims.Private.RedirectUri),
+
+                _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0340))
+            };
+
+            // If the endpoint URI cannot be resolved, this likely means the authorization or
+            // logout request was sent without a redirect_uri/post_logout_redirect_uri attached.
+            if (string.IsNullOrEmpty(value))
+            {
+                return default;
+            }
+
+            // Compare the current HTTP request address to the original endpoint URI. If the two don't
+            // match, this may indicate a mix-up attack. While the authorization server is expected to
+            // abort the authorization flow by rejecting the token request that may be eventually sent
+            // with the original endpoint URI, many servers are known to incorrectly implement this
+            // endpoint URI validation logic. This check also offers limited protection as it cannot
+            // prevent the authorization code from being leaked to a malicious authorization server.
+            // By comparing the endpoint URI directly in the client, a first layer of protection is
+            // provided independently of whether the authorization server will enforce this check.
+            //
+            // See https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-19#section-4.4.2.2
+            // for more information.
+            var address = new Uri(value, UriKind.Absolute);
+            if (new UriBuilder(address) { Query = null }.Uri !=
+                new UriBuilder(context.RequestUri!) { Query = null }.Uri)
+            {
+                context.Reject(
+                    error: Errors.InvalidRequest,
+                    description: SR.GetResourceString(SR.ID2138),
+                    uri: SR.FormatID8000(SR.ID2138));
+
+                return default;
+            }
+
+            // Ensure all the query string parameters that were part of the original endpoint URI
+            // are present in the current request (parameters that were not part of the original
+            // endpoint URI are assumed to be authorization response parameters and are ignored).
+            if (!string.IsNullOrEmpty(address.Query))
+            {
+                var parameters = OpenIddictHelpers.ParseQuery(context.RequestUri!.Query);
+
+                foreach (var parameter in OpenIddictHelpers.ParseQuery(address.Query))
+                {
+                    if (!parameters.TryGetValue(parameter.Key, out StringValues values) ||
+                        !parameter.Value.Equals(values))
+                    {
+                        context.Reject(
+                            error: Errors.InvalidRequest,
+                            description: SR.GetResourceString(SR.ID2138),
+                            uri: SR.FormatID8000(SR.ID2138));
+
+                        return default;
+                    }
+                }
+            }
+
+            return default;
+        }
+    }
+
     /// <summary>
     /// Contains the logic responsible for resolving the client registration
     /// based on the authorization server identity stored in the state token.
@@ -708,12 +891,6 @@ public static partial class OpenIddictClientHandlers
             // Resolve and attach the server configuration to the context.
             context.Configuration = await context.Registration.ConfigurationManager.GetConfigurationAsync(default) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-            // Ensure the issuer resolved from the configuration matches the expected value.
-            if (context.Configuration.Issuer != context.Issuer)
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
-            }
         }
     }
 
@@ -3617,12 +3794,6 @@ public static partial class OpenIddictClientHandlers
             // Resolve and attach the server configuration to the context if none has been set already.
             context.Configuration ??= await context.Registration.ConfigurationManager.GetConfigurationAsync(default) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-            // Ensure the issuer resolved from the configuration matches the expected value.
-            if (context.Configuration.Issuer != context.Issuer)
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
-            }
         }
     }
 
@@ -4076,10 +4247,13 @@ public static partial class OpenIddictClientHandlers
             }
 
             // Unlike OpenID Connect, OAuth 2.0 and 2.1 don't require specifying a redirect_uri.
+            //
             // To keep OpenIddict compatible with OAuth 2.0/2.1 deployments, the redirect_uri
             // is not required for OAuth 2.0 requests but an exception will be thrown later
             // if the request that is being prepared is an OpenID Connect request.
-            context.RedirectUri ??= context.Registration.RedirectUri?.AbsoluteUri;
+            context.RedirectUri ??= OpenIddictHelpers.CreateAbsoluteUri(
+                context.BaseUri,
+                context.Registration.RedirectUri)?.AbsoluteUri;
 
             return default;
         }
@@ -4303,7 +4477,7 @@ public static partial class OpenIddictClientHandlers
     /// Contains the logic responsible for preparing and attaching the claims principal
     /// used to generate the state token, if one is going to be returned.
     /// </summary>
-    public sealed class PrepareStateTokenPrincipal : IOpenIddictClientHandler<ProcessChallengeContext>
+    public sealed class PrepareLoginStateTokenPrincipal : IOpenIddictClientHandler<ProcessChallengeContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -4311,7 +4485,7 @@ public static partial class OpenIddictClientHandlers
         public static OpenIddictClientHandlerDescriptor Descriptor { get; }
             = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessChallengeContext>()
                 .AddFilter<RequireLoginStateTokenGenerated>()
-                .UseSingletonHandler<PrepareStateTokenPrincipal>()
+                .UseSingletonHandler<PrepareLoginStateTokenPrincipal>()
                 .SetOrder(AttachCodeChallengeParameters.Descriptor.Order + 1_000)
                 .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
@@ -4360,6 +4534,9 @@ public static partial class OpenIddictClientHandlers
                 principal.SetExpirationDate(principal.GetCreationDate() + lifetime.Value);
             }
 
+            // Use the client identity as the token issuer.
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.ClientUri ?? context.BaseUri)?.AbsoluteUri);
+
             // Store the identity of the authorization server in the state token principal to allow
             // resolving it when handling the authorization callback. Note: additional security checks
             // are generally required to ensure the state token was not replaced with a state token
@@ -4418,11 +4595,11 @@ public static partial class OpenIddictClientHandlers
     /// <summary>
     /// Contains the logic responsible for generating a state token for the current challenge operation.
     /// </summary>
-    public sealed class GenerateStateToken : IOpenIddictClientHandler<ProcessChallengeContext>
+    public sealed class GenerateLoginStateToken : IOpenIddictClientHandler<ProcessChallengeContext>
     {
         private readonly IOpenIddictClientDispatcher _dispatcher;
 
-        public GenerateStateToken(IOpenIddictClientDispatcher dispatcher)
+        public GenerateLoginStateToken(IOpenIddictClientDispatcher dispatcher)
             => _dispatcher = dispatcher ?? throw new ArgumentNullException(nameof(dispatcher));
 
         /// <summary>
@@ -4431,7 +4608,7 @@ public static partial class OpenIddictClientHandlers
         public static OpenIddictClientHandlerDescriptor Descriptor { get; }
             = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessChallengeContext>()
                 .AddFilter<RequireLoginStateTokenGenerated>()
-                .UseScopedHandler<GenerateStateToken>()
+                .UseScopedHandler<GenerateLoginStateToken>()
                 .SetOrder(100_000)
                 .SetType(OpenIddictClientHandlerType.BuiltIn)
                 .Build();
@@ -4493,7 +4670,7 @@ public static partial class OpenIddictClientHandlers
             = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessChallengeContext>()
                 .AddFilter<RequireInteractiveGrantType>()
                 .UseSingletonHandler<ValidateRedirectUriParameter>()
-                .SetOrder(GenerateStateToken.Descriptor.Order + 1_000)
+                .SetOrder(GenerateLoginStateToken.Descriptor.Order + 1_000)
                 .Build();
 
         /// <inheritdoc/>
@@ -4724,12 +4901,6 @@ public static partial class OpenIddictClientHandlers
             // Resolve and attach the server configuration to the context if none has been set already.
             context.Configuration ??= await context.Registration.ConfigurationManager.GetConfigurationAsync(default) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-            // Ensure the issuer resolved from the configuration matches the expected value.
-            if (context.Configuration.Issuer != context.Issuer)
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
-            }
         }
     }
 
@@ -4785,7 +4956,9 @@ public static partial class OpenIddictClientHandlers
             }
 
             // Note: the post_logout_redirect_uri parameter is optional.
-            context.PostLogoutRedirectUri ??= context.Registration.PostLogoutRedirectUri?.AbsoluteUri;
+            context.PostLogoutRedirectUri ??= OpenIddictHelpers.CreateAbsoluteUri(
+                context.BaseUri,
+                context.Registration.PostLogoutRedirectUri)?.AbsoluteUri;
 
             return default;
         }
@@ -4973,6 +5146,9 @@ public static partial class OpenIddictClientHandlers
                 principal.SetExpirationDate(principal.GetCreationDate() + lifetime.Value);
             }
 
+            // Use the client identity as the token issuer.
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.ClientUri ?? context.BaseUri)?.AbsoluteUri);
+
             // Store the identity of the authorization server in the state token
             // principal to allow resolving it when handling the post-logout callback.
             //

src/OpenIddict.Client/OpenIddictClientOptions.cs

@@ -15,6 +15,12 @@ namespace OpenIddict.Client;
 /// </summary>
 public sealed class OpenIddictClientOptions
 {
+    /// <summary>
+    /// Gets or sets the optional address used to uniquely identify the client/relying party.
+    /// The URI must be absolute and may contain a path, but no query string or fragment part.
+    /// </summary>
+    public Uri? ClientUri { get; set; }
+
     /// <summary>
     /// Gets the list of the handlers responsible for processing the OpenIddict client operations.
     /// Note: the list is automatically sorted based on the order assigned to each handler descriptor.

src/OpenIddict.Client/OpenIddictClientService.cs

@@ -571,7 +571,6 @@ public sealed class OpenIddictClientService
                 var context = new PrepareConfigurationRequestContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -593,7 +592,6 @@ public sealed class OpenIddictClientService
                 var context = new ApplyConfigurationRequestContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -617,7 +615,6 @@ public sealed class OpenIddictClientService
                 var context = new ExtractConfigurationResponseContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -643,7 +640,6 @@ public sealed class OpenIddictClientService
                 var context = new HandleConfigurationResponseContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request,
                     Response = response
@@ -730,7 +726,6 @@ public sealed class OpenIddictClientService
                 var context = new PrepareCryptographyRequestContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -752,7 +747,6 @@ public sealed class OpenIddictClientService
                 var context = new ApplyCryptographyRequestContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -776,7 +770,6 @@ public sealed class OpenIddictClientService
                 var context = new ExtractCryptographyResponseContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -802,7 +795,6 @@ public sealed class OpenIddictClientService
                 var context = new HandleCryptographyResponseContext(transaction)
                 {
                     Address = address,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request,
                     Response = response
@@ -898,7 +890,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -921,7 +912,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -946,7 +936,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -973,7 +962,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request,
                     Response = response
@@ -1063,7 +1051,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -1086,7 +1073,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -1111,7 +1097,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request
                 };
@@ -1138,7 +1123,6 @@ public sealed class OpenIddictClientService
                 {
                     Address = address,
                     Configuration = configuration,
-                    Issuer = registration.Issuer,
                     Registration = registration,
                     Request = request,
                     Response = response,

src/OpenIddict.Client/OpenIddictClientTransaction.cs

@@ -21,9 +21,14 @@ public sealed class OpenIddictClientTransaction
     public OpenIddictClientEndpointType EndpointType { get; set; }
 
     /// <summary>
-    /// Gets or sets the issuer address associated with the current transaction, if available.
+    /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
     /// </summary>
-    public Uri? Issuer { get; set; }
+    public Uri? RequestUri { get; set; }
+
+    /// <summary>
+    /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+    /// </summary>
+    public Uri? BaseUri { get; set; }
 
     /// <summary>
     /// Gets or sets the logger associated with the current request.

src/OpenIddict.Owin/OpenIddict.Owin.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <Description>Versatile OpenID Connect stack for OWIN/Katana 4.1 (compatible with ASP.NET 4.6.1 and newer).</Description>
+    <Description>Versatile OpenID Connect stack for OWIN/Katana (compatible with ASP.NET 4.6.1 and newer).</Description>
     <PackageTags>$(PackageTags);aspnet;katana;owin;client;server;validation</PackageTags>
   </PropertyGroup>
 

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.Authentication.cs

@@ -113,8 +113,8 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
 
                 var parameters = context.Options.TokenValidationParameters.Clone();
-                parameters.ValidIssuer ??= context.Issuer?.AbsoluteUri;
-                parameters.ValidAudience = context.Issuer?.AbsoluteUri;
+                parameters.ValidIssuer ??= (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri;
+                parameters.ValidAudience ??= parameters.ValidIssuer;
                 parameters.ValidTypes = new[] { JsonWebTokenTypes.Private.AuthorizationRequest };
 
                 var result = await context.Options.JsonWebTokenHandler.ValidateTokenAsync(token, parameters);
@@ -231,9 +231,9 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 // Store the serialized authorization request parameters in the distributed cache.
                 var token = context.Options.JsonWebTokenHandler.CreateToken(new SecurityTokenDescriptor
                 {
-                    Audience = context.Issuer?.AbsoluteUri,
+                    Audience = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     EncryptingCredentials = context.Options.EncryptionCredentials.First(),
-                    Issuer = context.Issuer?.AbsoluteUri,
+                    Issuer = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     SigningCredentials = context.Options.SigningCredentials.First(),
                     Subject = new ClaimsIdentity(claims, TokenValidationParameters.DefaultAuthenticationType),
                     TokenType = JsonWebTokenTypes.Private.AuthorizationRequest

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.Session.cs

@@ -110,8 +110,8 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
 
                 var parameters = context.Options.TokenValidationParameters.Clone();
-                parameters.ValidIssuer ??= context.Issuer?.AbsoluteUri;
-                parameters.ValidAudience = context.Issuer?.AbsoluteUri;
+                parameters.ValidIssuer ??= (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri;
+                parameters.ValidAudience ??= parameters.ValidIssuer;
                 parameters.ValidTypes = new[] { JsonWebTokenTypes.Private.LogoutRequest };
 
                 var result = await context.Options.JsonWebTokenHandler.ValidateTokenAsync(token, parameters);
@@ -228,9 +228,9 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 // Store the serialized logout request parameters in the distributed cache.
                 var token = context.Options.JsonWebTokenHandler.CreateToken(new SecurityTokenDescriptor
                 {
-                    Audience = context.Issuer?.AbsoluteUri,
+                    Audience = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     EncryptingCredentials = context.Options.EncryptionCredentials.First(),
-                    Issuer = context.Issuer?.AbsoluteUri,
+                    Issuer = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     SigningCredentials = context.Options.SigningCredentials.First(),
                     Subject = new ClaimsIdentity(claims, TokenValidationParameters.DefaultAuthenticationType),
                     TokenType = JsonWebTokenTypes.Private.LogoutRequest

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.cs

@@ -12,6 +12,7 @@ using System.Text.Encodings.Web;
 using System.Text.Json;
 using Microsoft.AspNetCore;
 using Microsoft.AspNetCore.Diagnostics;
+using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Net.Http.Headers;
@@ -30,9 +31,9 @@ public static partial class OpenIddictServerAspNetCoreHandlers
         /*
          * Top-level request processing:
          */
-        InferEndpointType.Descriptor,
-        InferIssuerFromHost.Descriptor,
+        ResolveRequestUri.Descriptor,
         ValidateTransportSecurityRequirement.Descriptor,
+        ValidateHostHeader.Descriptor,
 
         /*
          * Challenge processing:
@@ -59,10 +60,10 @@ public static partial class OpenIddictServerAspNetCoreHandlers
         .AddRange(Userinfo.DefaultHandlers);
 
     /// <summary>
-    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// Contains the logic responsible for resolving the request URI from the ASP.NET Core environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
     /// </summary>
-    public sealed class InferEndpointType : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -70,7 +71,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireHttpRequest>()
-                .UseSingletonHandler<InferEndpointType>()
+                .UseSingletonHandler<ResolveRequestUri>()
                 .SetOrder(int.MinValue + 50_000)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
@@ -88,84 +89,45 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            context.EndpointType =
-                Matches(request, context.Options.AuthorizationEndpointUris) ? OpenIddictServerEndpointType.Authorization :
-                Matches(request, context.Options.ConfigurationEndpointUris) ? OpenIddictServerEndpointType.Configuration :
-                Matches(request, context.Options.CryptographyEndpointUris)  ? OpenIddictServerEndpointType.Cryptography  :
-                Matches(request, context.Options.DeviceEndpointUris)        ? OpenIddictServerEndpointType.Device        :
-                Matches(request, context.Options.IntrospectionEndpointUris) ? OpenIddictServerEndpointType.Introspection :
-                Matches(request, context.Options.LogoutEndpointUris)        ? OpenIddictServerEndpointType.Logout        :
-                Matches(request, context.Options.RevocationEndpointUris)    ? OpenIddictServerEndpointType.Revocation    :
-                Matches(request, context.Options.TokenEndpointUris)         ? OpenIddictServerEndpointType.Token         :
-                Matches(request, context.Options.UserinfoEndpointUris)      ? OpenIddictServerEndpointType.Userinfo      :
-                Matches(request, context.Options.VerificationEndpointUris)  ? OpenIddictServerEndpointType.Verification  :
-                                                                              OpenIddictServerEndpointType.Unknown;
-
-            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown)
-            {
-                context.Logger.LogInformation(SR.GetResourceString(SR.ID6053), context.EndpointType);
-            }
-
-            return default;
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
 
-            static bool Matches(HttpRequest request, IReadOnlyList<Uri> addresses)
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                for (var index = 0; index < addresses.Count; index++)
-                {
-                    var address = addresses[index];
-                    if (address.IsAbsoluteUri)
+                { HasValue: true } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: new Uri(request.GetEncodedUrl(), UriKind.Absolute)),
+
+                { HasValue: false } => (
+                    BaseUri: new UriBuilder
                     {
-                        // If the request host is not available (e.g because HTTP/1.0 was used), ignore absolute URLs.
-                        if (!request.Host.HasValue)
-                        {
-                            continue;
-                        }
-
-                        // Create a Uri instance using the request scheme and raw host and compare the two base addresses.
-                        if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host, UriKind.Absolute, out Uri? uri) ||
-                            !uri.IsWellFormedOriginalString() || uri.Port != address.Port ||
-                            !string.Equals(uri.Scheme, address.Scheme, StringComparison.OrdinalIgnoreCase) ||
-                            !string.Equals(uri.Host, address.Host, StringComparison.OrdinalIgnoreCase))
-                        {
-                            continue;
-                        }
-
-                        var path = PathString.FromUriComponent(address);
-                        if (AreEquivalent(path, request.PathBase + request.Path))
-                        {
-                            return true;
-                        }
-                    }
-
-                    else if (address.OriginalString.StartsWith("/", StringComparison.OrdinalIgnoreCase))
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
                     {
-                        var path = new PathString(address.OriginalString);
-                        if (AreEquivalent(path, request.Path))
-                        {
-                            return true;
-                        }
-                    }
-                }
-
-                return false;
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
 
-                // ASP.NET Core's routing system ignores trailing slashes when determining
-                // whether the request path matches a registered route, which is not the case
-                // with PathString, that treats /connect/token and /connect/token/ as different
-                // addresses. To mitigate this inconsistency, a manual check is used here.
-                static bool AreEquivalent(PathString left, PathString right)
-                    => left.Equals(right, StringComparison.OrdinalIgnoreCase) ||
-                       left.Equals(right + "/", StringComparison.OrdinalIgnoreCase) ||
-                       right.Equals(left + "/", StringComparison.OrdinalIgnoreCase);
-            }
+            return default;
         }
     }
 
     /// <summary>
-    /// Contains the logic responsible for infering the issuer URL from the HTTP request host and validating it.
+    /// Contains the logic responsible for rejecting OpenID Connect requests that don't use transport security.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
     /// </summary>
-    public sealed class InferIssuerFromHost : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ValidateTransportSecurityRequirement : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -173,8 +135,9 @@ public static partial class OpenIddictServerAspNetCoreHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireHttpRequest>()
-                .UseSingletonHandler<InferIssuerFromHost>()
-                .SetOrder(InferEndpointType.Descriptor.Order + 1_000)
+                .AddFilter<RequireTransportSecurityRequirementEnabled>()
+                .UseSingletonHandler<ValidateTransportSecurityRequirement>()
+                .SetOrder(InferEndpointType.Descriptor.Order + 250)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
 
@@ -191,45 +154,26 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            // Don't require that the request host be present if the request is not handled
-            // by an OpenIddict endpoint or if an explicit issuer URL was already set.
-            if (context.Issuer is not null || context.EndpointType is OpenIddictServerEndpointType.Unknown)
-            {
-                return default;
-            }
-
-            if (!request.Host.HasValue)
+            // Don't require that transport security be used if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown && !request.IsHttps)
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.FormatID2081(HeaderNames.Host),
-                    uri: SR.FormatID8000(SR.ID2081));
-
-                return default;
-            }
-
-            if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host + request.PathBase, UriKind.Absolute, out Uri? issuer) ||
-                !issuer.IsWellFormedOriginalString())
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.FormatID2082(HeaderNames.Host),
-                    uri: SR.FormatID8000(SR.ID2082));
+                    description: SR.GetResourceString(SR.ID2083),
+                    uri: SR.FormatID8000(SR.ID2083));
 
                 return default;
             }
 
-            context.Issuer = issuer;
-
             return default;
         }
     }
 
     /// <summary>
-    /// Contains the logic responsible for rejecting OpenID Connect requests that don't use transport security.
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
     /// </summary>
-    public sealed class ValidateTransportSecurityRequirement : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ValidateHostHeader : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -237,9 +181,8 @@ public static partial class OpenIddictServerAspNetCoreHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireHttpRequest>()
-                .AddFilter<RequireTransportSecurityRequirementEnabled>()
-                .UseSingletonHandler<ValidateTransportSecurityRequirement>()
-                .SetOrder(InferIssuerFromHost.Descriptor.Order + 1_000)
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(ValidateTransportSecurityRequirement.Descriptor.Order + 250)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
 
@@ -256,18 +199,13 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            // Don't require that the host be present if the request is not handled by OpenIddict.
-            if (context.EndpointType is OpenIddictServerEndpointType.Unknown)
-            {
-                return default;
-            }
-
-            if (!request.IsHttps)
+            // Don't require that the request host be present if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown && !request.Host.HasValue)
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2083),
-                    uri: SR.FormatID8000(SR.ID2083));
+                    description: SR.FormatID2081(HeaderNames.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
 
                 return default;
             }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.Authentication.cs

@@ -112,8 +112,8 @@ public static partial class OpenIddictServerOwinHandlers
                 }
 
                 var parameters = context.Options.TokenValidationParameters.Clone();
-                parameters.ValidIssuer ??= context.Issuer?.AbsoluteUri;
-                parameters.ValidAudience = context.Issuer?.AbsoluteUri;
+                parameters.ValidIssuer ??= (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri;
+                parameters.ValidAudience ??= parameters.ValidIssuer;
                 parameters.ValidTypes = new[] { JsonWebTokenTypes.Private.AuthorizationRequest };
 
                 var result = await context.Options.JsonWebTokenHandler.ValidateTokenAsync(token, parameters);
@@ -227,9 +227,9 @@ public static partial class OpenIddictServerOwinHandlers
                 // Store the serialized authorization request parameters in the distributed cache.
                 var token = context.Options.JsonWebTokenHandler.CreateToken(new SecurityTokenDescriptor
                 {
-                    Audience = context.Issuer?.AbsoluteUri,
+                    Audience = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     EncryptingCredentials = context.Options.EncryptionCredentials.First(),
-                    Issuer = context.Issuer?.AbsoluteUri,
+                    Issuer = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     SigningCredentials = context.Options.SigningCredentials.First(),
                     Subject = new ClaimsIdentity(claims, TokenValidationParameters.DefaultAuthenticationType),
                     TokenType = JsonWebTokenTypes.Private.AuthorizationRequest

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.Session.cs

@@ -110,8 +110,8 @@ public static partial class OpenIddictServerOwinHandlers
                 }
 
                 var parameters = context.Options.TokenValidationParameters.Clone();
-                parameters.ValidIssuer ??= context.Issuer?.AbsoluteUri;
-                parameters.ValidAudience = context.Issuer?.AbsoluteUri;
+                parameters.ValidIssuer ??= (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri;
+                parameters.ValidAudience ??= parameters.ValidIssuer;
                 parameters.ValidTypes = new[] { JsonWebTokenTypes.Private.LogoutRequest };
 
                 var result = await context.Options.JsonWebTokenHandler.ValidateTokenAsync(token, parameters);
@@ -225,9 +225,9 @@ public static partial class OpenIddictServerOwinHandlers
                 // Store the serialized logout request parameters in the distributed cache.
                 var token = context.Options.JsonWebTokenHandler.CreateToken(new SecurityTokenDescriptor
                 {
-                    Audience = context.Issuer?.AbsoluteUri,
+                    Audience = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     EncryptingCredentials = context.Options.EncryptionCredentials.First(),
-                    Issuer = context.Issuer?.AbsoluteUri,
+                    Issuer = (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri,
                     SigningCredentials = context.Options.SigningCredentials.First(),
                     Subject = new ClaimsIdentity(claims, TokenValidationParameters.DefaultAuthenticationType),
                     TokenType = JsonWebTokenTypes.Private.LogoutRequest

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs

@@ -26,9 +26,9 @@ public static partial class OpenIddictServerOwinHandlers
         /*
          * Top-level request processing:
          */
-        InferEndpointType.Descriptor,
-        InferIssuerFromHost.Descriptor,
+        ResolveRequestUri.Descriptor,
         ValidateTransportSecurityRequirement.Descriptor,
+        ValidateHostHeader.Descriptor,
 
         /*
          * Challenge processing:
@@ -55,10 +55,10 @@ public static partial class OpenIddictServerOwinHandlers
         .AddRange(Userinfo.DefaultHandlers);
 
     /// <summary>
-    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// Contains the logic responsible for resolving the request URI from the OWIN environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
     /// </summary>
-    public sealed class InferEndpointType : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -66,9 +66,7 @@ public static partial class OpenIddictServerOwinHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireOwinRequest>()
-                .UseSingletonHandler<InferEndpointType>()
-                // Note: this handler must be invoked before any other handler,
-                // including the built-in handlers defined in OpenIddict.Server.
+                .UseSingletonHandler<ResolveRequestUri>()
                 .SetOrder(int.MinValue + 50_000)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
@@ -86,84 +84,45 @@ public static partial class OpenIddictServerOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            context.EndpointType =
-                Matches(request, context.Options.AuthorizationEndpointUris) ? OpenIddictServerEndpointType.Authorization :
-                Matches(request, context.Options.ConfigurationEndpointUris) ? OpenIddictServerEndpointType.Configuration :
-                Matches(request, context.Options.CryptographyEndpointUris)  ? OpenIddictServerEndpointType.Cryptography  :
-                Matches(request, context.Options.DeviceEndpointUris)        ? OpenIddictServerEndpointType.Device        :
-                Matches(request, context.Options.IntrospectionEndpointUris) ? OpenIddictServerEndpointType.Introspection :
-                Matches(request, context.Options.LogoutEndpointUris)        ? OpenIddictServerEndpointType.Logout        :
-                Matches(request, context.Options.RevocationEndpointUris)    ? OpenIddictServerEndpointType.Revocation    :
-                Matches(request, context.Options.TokenEndpointUris)         ? OpenIddictServerEndpointType.Token         :
-                Matches(request, context.Options.UserinfoEndpointUris)      ? OpenIddictServerEndpointType.Userinfo      :
-                Matches(request, context.Options.VerificationEndpointUris)  ? OpenIddictServerEndpointType.Verification  :
-                                                                              OpenIddictServerEndpointType.Unknown;
-
-            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown)
-            {
-                context.Logger.LogInformation(SR.GetResourceString(SR.ID6053), context.EndpointType);
-            }
-
-            return default;
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
 
-            static bool Matches(IOwinRequest request, IReadOnlyList<Uri> addresses)
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                for (var index = 0; index < addresses.Count; index++)
-                {
-                    var address = addresses[index];
-                    if (address.IsAbsoluteUri)
-                    {
-                        // If the request host is not available (e.g because HTTP/1.0 was used), ignore absolute URLs.
-                        if (string.IsNullOrEmpty(request.Host.Value))
-                        {
-                            continue;
-                        }
-
-                        // Create a Uri instance using the request scheme and raw host and compare the two base addresses.
-                        if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host, UriKind.Absolute, out Uri? uri) ||
-                            !uri.IsWellFormedOriginalString() || uri.Port != address.Port ||
-                            !string.Equals(uri.Scheme, address.Scheme, StringComparison.OrdinalIgnoreCase) ||
-                            !string.Equals(uri.Host, address.Host, StringComparison.OrdinalIgnoreCase))
-                        {
-                            continue;
-                        }
-
-                        var path = PathString.FromUriComponent(address);
-                        if (AreEquivalent(path, request.PathBase + request.Path))
-                        {
-                            return true;
-                        }
-                    }
+                { Value.Length: > 0 } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: request.Uri),
 
-                    else if (address.OriginalString.StartsWith("/", StringComparison.OrdinalIgnoreCase))
+                { Value: null or { Length: 0 } } => (
+                    BaseUri: new UriBuilder
                     {
-                        var path = new PathString(address.OriginalString);
-                        if (AreEquivalent(path, request.Path))
-                        {
-                            return true;
-                        }
-                    }
-                }
-
-                return false;
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
 
-                // ASP.NET MVC's routing system ignores trailing slashes when determining
-                // whether the request path matches a registered route, which is not the case
-                // with PathString, that treats /connect/token and /connect/token/ as different
-                // addresses. To mitigate this inconsistency, a manual check is used here.
-                static bool AreEquivalent(PathString left, PathString right)
-                    => left.Equals(right, StringComparison.OrdinalIgnoreCase) ||
-                       left.Equals(right + new PathString("/"), StringComparison.OrdinalIgnoreCase) ||
-                       right.Equals(left + new PathString("/"), StringComparison.OrdinalIgnoreCase);
-            }
+            return default;
         }
     }
 
     /// <summary>
-    /// Contains the logic responsible for infering the issuer URL from the HTTP request host and validating it.
+    /// Contains the logic responsible for rejecting OpenID Connect requests that don't use transport security.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
     /// </summary>
-    public sealed class InferIssuerFromHost : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ValidateTransportSecurityRequirement : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -171,8 +130,9 @@ public static partial class OpenIddictServerOwinHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireOwinRequest>()
-                .UseSingletonHandler<InferIssuerFromHost>()
-                .SetOrder(InferEndpointType.Descriptor.Order + 1_000)
+                .AddFilter<RequireTransportSecurityRequirementEnabled>()
+                .UseSingletonHandler<ValidateTransportSecurityRequirement>()
+                .SetOrder(InferEndpointType.Descriptor.Order + 250)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
 
@@ -189,45 +149,26 @@ public static partial class OpenIddictServerOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            // Don't require that the request host be present if the request is not handled
-            // by an OpenIddict endpoint or if an explicit issuer URL was already set.
-            if (context.Issuer is not null || context.EndpointType is OpenIddictServerEndpointType.Unknown)
-            {
-                return default;
-            }
-
-            if (string.IsNullOrEmpty(request.Host.Value))
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.FormatID2081(Headers.Host),
-                    uri: SR.FormatID8000(SR.ID2081));
-
-                return default;
-            }
-
-            if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host + request.PathBase, UriKind.Absolute, out Uri? issuer) ||
-                !issuer.IsWellFormedOriginalString())
+            // Don't require that transport security be used if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown && !request.IsSecure)
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.FormatID2082(Headers.Host),
-                    uri: SR.FormatID8000(SR.ID2082));
+                    description: SR.GetResourceString(SR.ID2083),
+                    uri: SR.FormatID8000(SR.ID2083));
 
                 return default;
             }
 
-            context.Issuer = issuer;
-
             return default;
         }
     }
 
     /// <summary>
-    /// Contains the logic responsible for rejecting OpenID Connect requests that don't use transport security.
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
     /// </summary>
-    public sealed class ValidateTransportSecurityRequirement : IOpenIddictServerHandler<ProcessRequestContext>
+    public sealed class ValidateHostHeader : IOpenIddictServerHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -235,9 +176,8 @@ public static partial class OpenIddictServerOwinHandlers
         public static OpenIddictServerHandlerDescriptor Descriptor { get; }
             = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireOwinRequest>()
-                .AddFilter<RequireTransportSecurityRequirementEnabled>()
-                .UseSingletonHandler<ValidateTransportSecurityRequirement>()
-                .SetOrder(InferIssuerFromHost.Descriptor.Order + 1_000)
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(ValidateTransportSecurityRequirement.Descriptor.Order + 250)
                 .SetType(OpenIddictServerHandlerType.BuiltIn)
                 .Build();
 
@@ -254,18 +194,14 @@ public static partial class OpenIddictServerOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            // Don't require that the host be present if the request is not handled by OpenIddict.
-            if (context.EndpointType is OpenIddictServerEndpointType.Unknown)
-            {
-                return default;
-            }
-
-            if (!request.IsSecure)
+            // Don't require that the request host be present if the request is not handled by OpenIddict.
+            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown &&
+                string.IsNullOrEmpty(request.Host.Value))
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.GetResourceString(SR.ID2083),
-                    uri: SR.FormatID8000(SR.ID2083));
+                    description: SR.FormatID2081(Headers.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
 
                 return default;
             }

src/OpenIddict.Server/OpenIddictServerBuilder.cs

@@ -1714,8 +1714,8 @@ public sealed class OpenIddictServerBuilder
         => Configure(options => options.UserCodeLifetime = lifetime);
 
     /// <summary>
-    /// Sets the issuer address, which is used as the base address
-    /// for the endpoint URIs returned from the discovery endpoint.
+    /// Sets the issuer address, which is used as the value for the "issuer" claim and
+    /// is returned from the discovery endpoint to identify the authorization server.
     /// </summary>
     /// <param name="address">The issuer address.</param>
     /// <returns>The <see cref="OpenIddictServerBuilder"/> instance.</returns>

src/OpenIddict.Server/OpenIddictServerEvents.Discovery.cs

@@ -86,6 +86,11 @@ public static partial class OpenIddictServerEvents
         /// </summary>
         public Dictionary<string, OpenIddictParameter> Metadata { get; } = new(StringComparer.Ordinal);
 
+        /// <summary>
+        /// Gets or sets the issuer address.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the authorization endpoint address.
         /// </summary>

src/OpenIddict.Server/OpenIddictServerEvents.Introspection.cs

@@ -125,6 +125,11 @@ public static partial class OpenIddictServerEvents
         /// </summary>
         public DateTimeOffset? IssuedAt { get; set; }
 
+        /// <summary>
+        /// Gets or sets the "iss" claim returned to the caller, if applicable.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the "nbf" claim
         /// returned to the caller, if applicable.

src/OpenIddict.Server/OpenIddictServerEvents.Userinfo.cs

@@ -144,6 +144,11 @@ public static partial class OpenIddictServerEvents
         /// </summary>
         public string? GivenName { get; set; }
 
+        /// <summary>
+        /// Gets or sets the value used for the "iss" claim.
+        /// </summary>
+        public Uri? Issuer { get; set; }
+
         /// <summary>
         /// Gets or sets the value used for the "phone_number" claim.
         /// Note: this value should only be populated if the "phone"

src/OpenIddict.Server/OpenIddictServerEvents.cs

@@ -30,21 +30,30 @@ public static partial class OpenIddictServerEvents
         public OpenIddictServerTransaction Transaction { get; }
 
         /// <summary>
-        /// Gets or sets the issuer address associated with the current transaction, if available.
+        /// Gets or sets the endpoint type that handled the request, if applicable.
         /// </summary>
-        public Uri? Issuer
+        public OpenIddictServerEndpointType EndpointType
         {
-            get => Transaction.Issuer;
-            set => Transaction.Issuer = value;
+            get => Transaction.EndpointType;
+            set => Transaction.EndpointType = value;
         }
 
         /// <summary>
-        /// Gets or sets the endpoint type that handled the request, if applicable.
+        /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
         /// </summary>
-        public OpenIddictServerEndpointType EndpointType
+        public Uri? RequestUri
         {
-            get => Transaction.EndpointType;
-            set => Transaction.EndpointType = value;
+            get => Transaction.RequestUri;
+            set => Transaction.RequestUri = value;
+        }
+
+        /// <summary>
+        /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+        /// </summary>
+        public Uri? BaseUri
+        {
+            get => Transaction.BaseUri;
+            set => Transaction.BaseUri = value;
         }
 
         /// <summary>

src/OpenIddict.Server/OpenIddictServerFactory.cs

@@ -30,7 +30,6 @@ public sealed class OpenIddictServerFactory : IOpenIddictServerFactory
     public ValueTask<OpenIddictServerTransaction> CreateTransactionAsync()
         => new(new OpenIddictServerTransaction
         {
-            Issuer = _options.CurrentValue.Issuer,
             Logger = _logger,
             Options = _options.CurrentValue
         });

src/OpenIddict.Server/OpenIddictServerHandlers.Authentication.cs

@@ -1933,19 +1933,16 @@ public static partial class OpenIddictServerHandlers
                 // Note: this applies to all authorization responses, whether they represent valid or errored responses.
                 // For more information, see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-iss-auth-resp-05.
 
-                if (!string.IsNullOrEmpty(context.RedirectUri))
+                // Note: don't override the issuer if one was already attached to the response instance.
+                if (!string.IsNullOrEmpty(context.RedirectUri) && string.IsNullOrEmpty(context.Response.Iss))
                 {
-                    // At this stage, throw an exception if the issuer cannot be retrieved.
-                    if (context.Issuer is not { IsAbsoluteUri: true })
+                    context.Response.Iss = (context.Options.Issuer ?? context.BaseUri) switch
                     {
-                        throw new InvalidOperationException(SR.GetResourceString(SR.ID0023));
-                    }
+                        { IsAbsoluteUri: true } uri => uri.AbsoluteUri,
 
-                    // Note: don't override the issuer if one was already attached to the response instance.
-                    if (string.IsNullOrEmpty(context.Response.Iss))
-                    {
-                        context.Response.Iss = context.Issuer.AbsoluteUri;
-                    }
+                        // At this stage, throw an exception if the issuer cannot be retrieved or is not valid.
+                        _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0023))
+                    };
                 }
 
                 return default;

src/OpenIddict.Server/OpenIddictServerHandlers.Discovery.cs

@@ -31,6 +31,7 @@ public static partial class OpenIddictServerHandlers
             /*
              * Configuration request handling:
              */
+            AttachIssuer.Descriptor,
             AttachEndpoints.Descriptor,
             AttachGrantTypes.Descriptor,
             AttachResponseModes.Descriptor,
@@ -310,6 +311,35 @@ public static partial class OpenIddictServerHandlers
             }
         }
 
+        /// <summary>
+        /// Contains the logic responsible for attaching the issuer to the provider discovery document.
+        /// </summary>
+        public sealed class AttachIssuer : IOpenIddictServerHandler<HandleConfigurationRequestContext>
+        {
+            /// <summary>
+            /// Gets the default descriptor definition assigned to this handler.
+            /// </summary>
+            public static OpenIddictServerHandlerDescriptor Descriptor { get; }
+                = OpenIddictServerHandlerDescriptor.CreateBuilder<HandleConfigurationRequestContext>()
+                    .UseSingletonHandler<AttachIssuer>()
+                    .SetOrder(int.MaxValue - 100_000)
+                    .SetType(OpenIddictServerHandlerType.BuiltIn)
+                    .Build();
+
+            /// <inheritdoc/>
+            public ValueTask HandleAsync(HandleConfigurationRequestContext context)
+            {
+                if (context is null)
+                {
+                    throw new ArgumentNullException(nameof(context));
+                }
+
+                context.Issuer = context.Options.Issuer ?? context.BaseUri;
+
+                return default;
+            }
+        }
+
         /// <summary>
         /// Contains the logic responsible for attaching the endpoint URLs to the provider discovery document.
         /// </summary>
@@ -321,7 +351,7 @@ public static partial class OpenIddictServerHandlers
             public static OpenIddictServerHandlerDescriptor Descriptor { get; }
                 = OpenIddictServerHandlerDescriptor.CreateBuilder<HandleConfigurationRequestContext>()
                     .UseSingletonHandler<AttachEndpoints>()
-                    .SetOrder(int.MaxValue - 100_000)
+                    .SetOrder(AttachIssuer.Descriptor.Order + 1_000)
                     .SetType(OpenIddictServerHandlerType.BuiltIn)
                     .Build();
 
@@ -336,68 +366,31 @@ public static partial class OpenIddictServerHandlers
                 // Note: while OpenIddict allows specifying multiple endpoint addresses, the OAuth 2.0
                 // and OpenID Connect discovery specifications only allow a single address per endpoint.
 
-                context.AuthorizationEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.AuthorizationEndpointUris.FirstOrDefault());
+                context.AuthorizationEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.AuthorizationEndpointUris.FirstOrDefault());
 
-                context.CryptographyEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.CryptographyEndpointUris.FirstOrDefault());
+                context.CryptographyEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.CryptographyEndpointUris.FirstOrDefault());
 
-                context.DeviceEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.DeviceEndpointUris.FirstOrDefault());
+                context.DeviceEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.DeviceEndpointUris.FirstOrDefault());
 
-                context.IntrospectionEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.IntrospectionEndpointUris.FirstOrDefault());
+                context.IntrospectionEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.IntrospectionEndpointUris.FirstOrDefault());
 
-                context.LogoutEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.LogoutEndpointUris.FirstOrDefault());
+                context.LogoutEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.LogoutEndpointUris.FirstOrDefault());
 
-                context.RevocationEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.RevocationEndpointUris.FirstOrDefault());
+                context.RevocationEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.RevocationEndpointUris.FirstOrDefault());
 
-                context.TokenEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.TokenEndpointUris.FirstOrDefault());
+                context.TokenEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.TokenEndpointUris.FirstOrDefault());
 
-                context.UserinfoEndpoint ??= GetEndpointAbsoluteUri(context.Issuer,
-                    context.Options.UserinfoEndpointUris.FirstOrDefault());
+                context.UserinfoEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
+                    context.BaseUri, context.Options.UserinfoEndpointUris.FirstOrDefault());
 
                 return default;
-
-                static Uri? GetEndpointAbsoluteUri(Uri? issuer, Uri? endpoint)
-                {
-                    // If the endpoint is disabled (i.e a null address is specified), return null.
-                    if (endpoint is null)
-                    {
-                        return null;
-                    }
-
-                    // If the endpoint address is already an absolute URL, return it as-is.
-                    if (endpoint.IsAbsoluteUri)
-                    {
-                        return endpoint;
-                    }
-
-                    // At this stage, throw an exception if the issuer cannot be retrieved.
-                    if (issuer is not { IsAbsoluteUri: true })
-                    {
-                        throw new InvalidOperationException(SR.GetResourceString(SR.ID0023));
-                    }
-
-                    // Ensure the issuer ends with a trailing slash, as it is necessary
-                    // for Uri's constructor to correctly compute correct absolute URLs.
-                    if (!issuer.OriginalString.EndsWith("/", StringComparison.Ordinal))
-                    {
-                        issuer = new Uri(issuer.OriginalString + "/", UriKind.Absolute);
-                    }
-
-                    // Ensure the endpoint does not start with a leading slash, as it is necessary
-                    // for Uri's constructor to correctly compute correct absolute URLs.
-                    if (endpoint.OriginalString.StartsWith("/", StringComparison.Ordinal))
-                    {
-                        endpoint = new Uri(endpoint.OriginalString[1..], UriKind.Relative);
-                    }
-
-                    return new Uri(issuer, endpoint);
-                }
             }
         }
 

src/OpenIddict.Server/OpenIddictServerHandlers.Introspection.cs

@@ -883,6 +883,8 @@ public static partial class OpenIddictServerHandlers
 
                 Debug.Assert(context.Principal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
 
+                context.Issuer = context.Options.Issuer ?? context.BaseUri;
+
                 context.TokenId = context.Principal.GetClaim(Claims.JwtId);
                 context.TokenUsage = context.Principal.GetTokenType();
                 context.Subject = context.Principal.GetClaim(Claims.Subject);

src/OpenIddict.Server/OpenIddictServerHandlers.Protection.cs

@@ -68,8 +68,24 @@ public static partial class OpenIddictServerHandlers
                 }
 
                 var parameters = context.Options.TokenValidationParameters.Clone();
-                parameters.ValidIssuer ??= context.Issuer?.AbsoluteUri;
-                parameters.ValidateIssuer = !string.IsNullOrEmpty(parameters.ValidIssuer);
+
+                parameters.ValidIssuers ??= (context.Options.Issuer ?? context.BaseUri) switch
+                {
+                    null => null,
+
+                    // If the issuer URI doesn't contain any path/query/fragment, allow both http://www.fabrikam.com
+                    // and http://www.fabrikam.com/ (the recommended URI representation) to be considered valid.
+                    // See https://datatracker.ietf.org/doc/html/rfc3986#section-6.2.3 for more information.
+                    { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } uri => new[]
+                    {
+                        uri.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
+                        uri.AbsoluteUri[..^1]
+                    },
+
+                    Uri uri => new[] { uri.AbsoluteUri }
+                };
+
+                parameters.ValidateIssuer = parameters.ValidIssuers is not null;
 
                 parameters.ValidTypes = context.ValidTokenTypes.Count switch
                 {

src/OpenIddict.Server/OpenIddictServerHandlers.Userinfo.cs

@@ -497,6 +497,7 @@ public static partial class OpenIddictServerHandlers
 
                 Debug.Assert(context.Principal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
 
+                context.Issuer = context.Options.Issuer ?? context.BaseUri;
                 context.Subject = context.Principal.GetClaim(Claims.Subject);
 
                 // The following claims are all optional and should be excluded when

src/OpenIddict.Server/OpenIddictServerHandlers.cs

@@ -8,7 +8,6 @@ using System.Collections.Immutable;
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Security.Claims;
-using System.Security.Cryptography;
 using System.Text;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.Tokens;
@@ -20,6 +19,11 @@ namespace OpenIddict.Server;
 public static partial class OpenIddictServerHandlers
 {
     public static ImmutableArray<OpenIddictServerHandlerDescriptor> DefaultHandlers { get; } = ImmutableArray.Create(
+        /*
+         * Top-level request processing:
+         */
+        InferEndpointType.Descriptor,
+
         /*
          * Authentication processing:
          */
@@ -101,6 +105,99 @@ public static partial class OpenIddictServerHandlers
         .AddRange(Session.DefaultHandlers)
         .AddRange(Userinfo.DefaultHandlers);
 
+    /// <summary>
+    /// Contains the logic responsible for inferring the endpoint type from the request address.
+    /// </summary>
+    public sealed class InferEndpointType : IOpenIddictServerHandler<ProcessRequestContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictServerHandlerDescriptor Descriptor { get; }
+            = OpenIddictServerHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
+                .UseSingletonHandler<InferEndpointType>()
+                .SetOrder(int.MinValue + 100_000)
+                .SetType(OpenIddictServerHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessRequestContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            if (context is not { BaseUri.IsAbsoluteUri: true, RequestUri.IsAbsoluteUri: true })
+            {
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0127));
+            }
+
+            context.EndpointType =
+                Matches(context.Options.AuthorizationEndpointUris) ? OpenIddictServerEndpointType.Authorization :
+                Matches(context.Options.ConfigurationEndpointUris) ? OpenIddictServerEndpointType.Configuration :
+                Matches(context.Options.CryptographyEndpointUris)  ? OpenIddictServerEndpointType.Cryptography  :
+                Matches(context.Options.DeviceEndpointUris)        ? OpenIddictServerEndpointType.Device        :
+                Matches(context.Options.IntrospectionEndpointUris) ? OpenIddictServerEndpointType.Introspection :
+                Matches(context.Options.LogoutEndpointUris)        ? OpenIddictServerEndpointType.Logout        :
+                Matches(context.Options.RevocationEndpointUris)    ? OpenIddictServerEndpointType.Revocation    :
+                Matches(context.Options.TokenEndpointUris)         ? OpenIddictServerEndpointType.Token         :
+                Matches(context.Options.UserinfoEndpointUris)      ? OpenIddictServerEndpointType.Userinfo      :
+                Matches(context.Options.VerificationEndpointUris)  ? OpenIddictServerEndpointType.Verification  :
+                                                                     OpenIddictServerEndpointType.Unknown;
+
+            if (context.EndpointType is not OpenIddictServerEndpointType.Unknown)
+            {
+                context.Logger.LogInformation(SR.GetResourceString(SR.ID6053), context.EndpointType);
+            }
+
+            return default;
+
+            bool Matches(IReadOnlyList<Uri> addresses)
+            {
+                for (var index = 0; index < addresses.Count; index++)
+                {
+                    var address = addresses[index];
+                    if (address.IsAbsoluteUri)
+                    {
+                        if (Equals(address, context.RequestUri))
+                        {
+                            return true;
+                        }
+                    }
+
+                    else
+                    {
+                        var uri = OpenIddictHelpers.CreateAbsoluteUri(context.BaseUri, address);
+                        if (uri.IsWellFormedOriginalString() &&
+                            OpenIddictHelpers.IsBaseOf(context.BaseUri, uri) && Equals(uri, context.RequestUri))
+                        {
+                            return true;
+                        }
+                    }
+                }
+
+                return false;
+            }
+
+            static bool Equals(Uri left, Uri right) =>
+                string.Equals(left.Scheme, right.Scheme, StringComparison.OrdinalIgnoreCase) &&
+                string.Equals(left.Host, right.Host, StringComparison.OrdinalIgnoreCase) &&
+                left.Port == right.Port &&
+                // Note: paths are considered equivalent even if the casing isn't identical or if one of the two
+                // paths only differs by a trailing slash, which matches the classical behavior seen on ASP.NET,
+                // Microsoft.Owin/Katana and ASP.NET Core. Developers who prefer a different behavior can remove
+                // this handler and replace it by a custom version implementing a more strict comparison logic.
+                (string.Equals(left.AbsolutePath, right.AbsolutePath, StringComparison.OrdinalIgnoreCase) ||
+                 (left.AbsolutePath.Length == right.AbsolutePath.Length + 1 &&
+                  left.AbsolutePath.StartsWith(right.AbsolutePath, StringComparison.OrdinalIgnoreCase) &&
+                  left.AbsolutePath[^1] is '/') ||
+                 (right.AbsolutePath.Length == left.AbsolutePath.Length + 1 &&
+                  right.AbsolutePath.StartsWith(left.AbsolutePath, StringComparison.OrdinalIgnoreCase) &&
+                  right.AbsolutePath[^1] is '/'));
+        }
+    }
+
     /// <summary>
     /// Contains the logic responsible for rejecting authentication demands made from unsupported endpoints.
     /// </summary>
@@ -1815,7 +1912,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             // Set the audiences based on the resource claims stored in the principal.
             principal.SetAudiences(context.Principal.GetResources());
@@ -1902,7 +1999,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             // Attach the redirect_uri to allow for later comparison when
             // receiving a grant_type=authorization_code token request.
@@ -1991,7 +2088,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             // Restore the device code internal token identifier from the principal
             // resolved from the user code used in the user code verification request.
@@ -2085,7 +2182,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             context.RefreshTokenPrincipal = principal;
 
@@ -2181,7 +2278,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             // If available, use the client_id as both the audience and the authorized party.
             // See https://openid.net/specs/openid-connect-core-1_0.html#IDToken for more information.
@@ -2269,7 +2366,7 @@ public static partial class OpenIddictServerHandlers
             }
 
             // Use the server identity as the token issuer.
-            principal.SetClaim(Claims.Private.Issuer, context.Issuer?.AbsoluteUri);
+            principal.SetClaim(Claims.Private.Issuer, (context.Options.Issuer ?? context.BaseUri)?.AbsoluteUri);
 
             // Store the client_id as a public client_id claim.
             principal.SetClaim(Claims.ClientId, context.Request.ClientId);
@@ -2976,7 +3073,8 @@ public static partial class OpenIddictServerHandlers
             {
                 context.Response.UserCode = context.UserCode;
 
-                var address = GetEndpointAbsoluteUri(context.Issuer, context.Options.VerificationEndpointUris.FirstOrDefault());
+                var address = OpenIddictHelpers.CreateAbsoluteUri(context.BaseUri,
+                    context.Options.VerificationEndpointUris.FirstOrDefault());
                 if (address is not null)
                 {
                     var builder = new UriBuilder(address)
@@ -2990,43 +3088,6 @@ public static partial class OpenIddictServerHandlers
             }
 
             return default;
-
-            static Uri? GetEndpointAbsoluteUri(Uri? issuer, Uri? endpoint)
-            {
-                // If the endpoint is disabled (i.e a null address is specified), return null.
-                if (endpoint is null)
-                {
-                    return null;
-                }
-
-                // If the endpoint address is already an absolute URL, return it as-is.
-                if (endpoint.IsAbsoluteUri)
-                {
-                    return endpoint;
-                }
-
-                // At this stage, throw an exception if the issuer cannot be retrieved.
-                if (issuer is not { IsAbsoluteUri: true })
-                {
-                    throw new InvalidOperationException(SR.GetResourceString(SR.ID0023));
-                }
-
-                // Ensure the issuer ends with a trailing slash, as it is necessary
-                // for Uri's constructor to correctly compute correct absolute URLs.
-                if (!issuer.OriginalString.EndsWith("/", StringComparison.Ordinal))
-                {
-                    issuer = new Uri(issuer.OriginalString + "/", UriKind.Absolute);
-                }
-
-                // Ensure the endpoint does not start with a leading slash, as it is necessary
-                // for Uri's constructor to correctly compute correct absolute URLs.
-                if (endpoint.OriginalString.StartsWith("/", StringComparison.Ordinal))
-                {
-                    endpoint = new Uri(endpoint.OriginalString[1..], UriKind.Relative);
-                }
-
-                return new Uri(issuer, endpoint);
-            }
         }
     }
 

src/OpenIddict.Server/OpenIddictServerOptions.cs

@@ -16,7 +16,7 @@ namespace OpenIddict.Server;
 public sealed class OpenIddictServerOptions
 {
     /// <summary>
-    /// Gets or sets the optional base address used to uniquely identify the authorization server.
+    /// Gets or sets the optional address used to uniquely identify the authorization server.
     /// The URI must be absolute and may contain a path, but no query string or fragment part.
     /// </summary>
     public Uri? Issuer { get; set; }
@@ -67,8 +67,8 @@ public sealed class OpenIddictServerOptions
     /// </summary>
     public List<Uri> ConfigurationEndpointUris { get; } = new()
     {
-        new Uri("/.well-known/openid-configuration", UriKind.Relative),
-        new Uri("/.well-known/oauth-authorization-server", UriKind.Relative)
+        new Uri(".well-known/openid-configuration", UriKind.Relative),
+        new Uri(".well-known/oauth-authorization-server", UriKind.Relative)
     };
 
     /// <summary>
@@ -76,7 +76,7 @@ public sealed class OpenIddictServerOptions
     /// </summary>
     public List<Uri> CryptographyEndpointUris { get; } = new()
     {
-        new Uri("/.well-known/jwks", UriKind.Relative)
+        new Uri(".well-known/jwks", UriKind.Relative)
     };
 
     /// <summary>

src/OpenIddict.Server/OpenIddictServerTransaction.cs

@@ -21,9 +21,14 @@ public sealed class OpenIddictServerTransaction
     public OpenIddictServerEndpointType EndpointType { get; set; }
 
     /// <summary>
-    /// Gets or sets the issuer address associated with the current transaction, if available.
+    /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
     /// </summary>
-    public Uri? Issuer { get; set; }
+    public Uri? RequestUri { get; set; }
+
+    /// <summary>
+    /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+    /// </summary>
+    public Uri? BaseUri { get; set; }
 
     /// <summary>
     /// Gets or sets the logger associated with the current request.

src/OpenIddict.Validation.AspNetCore/OpenIddictValidationAspNetCoreHandlers.cs

@@ -10,6 +10,7 @@ using System.Diagnostics;
 using System.Text;
 using System.Text.Json;
 using Microsoft.AspNetCore;
+using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
@@ -29,11 +30,12 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
         /*
          * Request top-level processing:
          */
-        InferIssuerFromHost.Descriptor,
+        ResolveRequestUri.Descriptor,
 
         /*
          * Authentication processing:
          */
+        ValidateHostHeader.Descriptor,
         ExtractAccessTokenFromAuthorizationHeader.Descriptor,
         ExtractAccessTokenFromBodyForm.Descriptor,
         ExtractAccessTokenFromQueryString.Descriptor,
@@ -58,10 +60,10 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
         ProcessChallengeErrorResponse<ProcessErrorContext>.Descriptor);
 
     /// <summary>
-    /// Contains the logic responsible for infering the default issuer from the HTTP request host and validating it.
+    /// Contains the logic responsible for resolving the request URI from the ASP.NET Core environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
     /// </summary>
-    public sealed class InferIssuerFromHost : IOpenIddictValidationHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictValidationHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -69,8 +71,8 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
         public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
             = OpenIddictValidationHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireHttpRequest>()
-                .UseSingletonHandler<InferIssuerFromHost>()
-                .SetOrder(int.MinValue + 100_000)
+                .UseSingletonHandler<ResolveRequestUri>()
+                .SetOrder(int.MinValue + 50_000)
                 .SetType(OpenIddictValidationHandlerType.BuiltIn)
                 .Build();
 
@@ -87,36 +89,81 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             var request = context.Transaction.GetHttpRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
 
-            // Only use the current host as the issuer if the
-            // issuer was not explicitly set in the options.
-            if (context.Issuer is not null)
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
+
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                return default;
-            }
+                { HasValue: true } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: new Uri(request.GetEncodedUrl(), UriKind.Absolute)),
 
-            if (!request.Host.HasValue)
-            {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.FormatID2081(HeaderNames.Host),
-                    uri: SR.FormatID8000(SR.ID2081));
+                { HasValue: false } => (
+                    BaseUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
 
-                return default;
+            return default;
+        }
+    }
+
+    /// <summary>
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
+    /// Note: this handler is not used when the OpenID Connect request is not initially handled by ASP.NET Core.
+    /// </summary>
+    public sealed class ValidateHostHeader : IOpenIddictValidationHandler<ProcessAuthenticationContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
+            = OpenIddictValidationHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
+                .AddFilter<RequireHttpRequest>()
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(int.MinValue + 50_000)
+                .SetType(OpenIddictValidationHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessAuthenticationContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
             }
 
-            if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host + request.PathBase, UriKind.Absolute, out Uri? issuer) ||
-                !issuer.IsWellFormedOriginalString())
+            // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
+            // this may indicate that the request was incorrectly processed by another server stack.
+            var request = context.Transaction.GetHttpRequest() ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0114));
+
+            // Don't require that a Host header be present if the issuer was set in the options.
+            if (context.Options.Issuer is null && !request.Host.HasValue)
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.FormatID2082(HeaderNames.Host),
-                    uri: SR.FormatID8000(SR.ID2082));
+                    description: SR.FormatID2081(HeaderNames.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
 
                 return default;
             }
 
-            context.Issuer = issuer;
-
             return default;
         }
     }

src/OpenIddict.Validation.Owin/OpenIddictValidationOwinHandlers.cs

@@ -25,7 +25,7 @@ public static partial class OpenIddictValidationOwinHandlers
         /*
          * Request top-level processing:
          */
-        InferIssuerFromHost.Descriptor,
+        ResolveRequestUri.Descriptor,
 
         /*
          * Authentication processing:
@@ -58,10 +58,10 @@ public static partial class OpenIddictValidationOwinHandlers
         ProcessChallengeErrorResponse<ProcessErrorContext>.Descriptor);
 
     /// <summary>
-    /// Contains the logic responsible for infering the default issuer from the HTTP request host and validating it.
+    /// Contains the logic responsible for resolving the request URI from the OWIN environment.
     /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
     /// </summary>
-    public sealed class InferIssuerFromHost : IOpenIddictValidationHandler<ProcessRequestContext>
+    public sealed class ResolveRequestUri : IOpenIddictValidationHandler<ProcessRequestContext>
     {
         /// <summary>
         /// Gets the default descriptor definition assigned to this handler.
@@ -69,8 +69,8 @@ public static partial class OpenIddictValidationOwinHandlers
         public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
             = OpenIddictValidationHandlerDescriptor.CreateBuilder<ProcessRequestContext>()
                 .AddFilter<RequireOwinRequest>()
-                .UseSingletonHandler<InferIssuerFromHost>()
-                .SetOrder(int.MinValue + 100_000)
+                .UseSingletonHandler<ResolveRequestUri>()
+                .SetOrder(int.MinValue + 50_000)
                 .SetType(OpenIddictValidationHandlerType.BuiltIn)
                 .Build();
 
@@ -87,36 +87,81 @@ public static partial class OpenIddictValidationOwinHandlers
             var request = context.Transaction.GetOwinRequest() ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
 
-            // Only use the current host as the issuer if the
-            // issuer was not explicitly set in the options.
-            if (context.Issuer is not null)
-            {
-                return default;
-            }
+            // OpenIddict supports both absolute and relative URIs for all its endpoints, but only absolute
+            // URIs can be properly canonicalized by the BCL System.Uri class (e.g './path/../' is normalized
+            // to './' once the URI is fully constructed). At this stage of the request processing, rejecting
+            // requests that lack the host information (e.g because HTTP/1.0 was used and no Host header was
+            // sent by the HTTP client) is not desirable as it would affect all requests, including requests
+            // that are not meant to be handled by OpenIddict itself. To avoid that, a fake host is temporarily
+            // used to build an absolute base URI and a request URI that will be used to determine whether the
+            // received request matches one of the addresses assigned to an OpenIddict endpoint. If the request
+            // is later handled by OpenIddict, an additional check will be made to require the Host header.
 
-            if (string.IsNullOrEmpty(request.Host.Value))
+            (context.BaseUri, context.RequestUri) = request.Host switch
             {
-                context.Reject(
-                    error: Errors.InvalidRequest,
-                    description: SR.FormatID2081(Headers.Host),
-                    uri: SR.FormatID8000(SR.ID2081));
+                { Value.Length: > 0 } host => (
+                    BaseUri: new Uri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase, UriKind.Absolute),
+                    RequestUri: request.Uri),
 
-                return default;
+                { Value: null or { Length: 0 } } => (
+                    BaseUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = request.PathBase.ToUriComponent()
+                    }.Uri,
+                    RequestUri: new UriBuilder
+                    {
+                        Scheme = request.Scheme,
+                        Path = (request.PathBase + request.Path).ToUriComponent(),
+                        Query = request.QueryString.ToUriComponent()
+                    }.Uri)
+            };
+
+            return default;
+        }
+    }
+
+    /// <summary>
+    /// Contains the logic responsible for validating the Host header extracted from the HTTP header.
+    /// Note: this handler is not used when the OpenID Connect request is not initially handled by OWIN.
+    /// </summary>
+    public sealed class ValidateHostHeader : IOpenIddictValidationHandler<ProcessAuthenticationContext>
+    {
+        /// <summary>
+        /// Gets the default descriptor definition assigned to this handler.
+        /// </summary>
+        public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
+            = OpenIddictValidationHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
+                .AddFilter<RequireOwinRequest>()
+                .UseSingletonHandler<ValidateHostHeader>()
+                .SetOrder(int.MinValue + 50_000)
+                .SetType(OpenIddictValidationHandlerType.BuiltIn)
+                .Build();
+
+        /// <inheritdoc/>
+        public ValueTask HandleAsync(ProcessAuthenticationContext context)
+        {
+            if (context is null)
+            {
+                throw new ArgumentNullException(nameof(context));
             }
 
-            if (!Uri.TryCreate(request.Scheme + Uri.SchemeDelimiter + request.Host + request.PathBase, UriKind.Absolute, out Uri? issuer) ||
-                !issuer.IsWellFormedOriginalString())
+            // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
+            // this may indicate that the request was incorrectly processed by another server stack.
+            var request = context.Transaction.GetOwinRequest() ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0120));
+
+            // Don't require that a Host header be present if the issuer was set in the options.
+            if (context.Options.Issuer is null && string.IsNullOrEmpty(request.Host.Value))
             {
                 context.Reject(
                     error: Errors.InvalidRequest,
-                    description: SR.FormatID2082(Headers.Host),
-                    uri: SR.FormatID8000(SR.ID2082));
+                    description: SR.FormatID2081(Headers.Host),
+                    uri: SR.FormatID8000(SR.ID2081));
 
                 return default;
             }
 
-            context.Issuer = issuer;
-
             return default;
         }
     }

src/OpenIddict.Validation.SystemNetHttp/OpenIddictValidationSystemNetHttpHandlers.Introspection.cs

@@ -53,7 +53,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                     .Build();
 
             /// <inheritdoc/>
-            public async ValueTask HandleAsync(PrepareIntrospectionRequestContext context)
+            public ValueTask HandleAsync(PrepareIntrospectionRequestContext context)
             {
                 if (context is null)
                 {
@@ -70,16 +70,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                 // If no client identifier was attached to the request, skip the following logic.
                 if (string.IsNullOrEmpty(context.Request.ClientId))
                 {
-                    return;
-                }
-
-                var configuration = await context.Options.ConfigurationManager.GetConfigurationAsync(default) ??
-                    throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-                // Ensure the issuer resolved from the configuration matches the expected value.
-                if (context.Options.Issuer is not null && configuration.Issuer != context.Options.Issuer)
-                {
-                    throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
+                    return default;
                 }
 
                 // The OAuth 2.0 specification recommends sending the client credentials using basic authentication.
@@ -93,7 +84,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                 //
                 // See https://tools.ietf.org/html/rfc8414#section-2
                 // and https://tools.ietf.org/html/rfc6749#section-2.3.1 for more information.
-                if (!configuration.IntrospectionEndpointAuthMethodsSupported.Contains(ClientAuthenticationMethods.ClientSecretPost))
+                if (!context.Configuration.IntrospectionEndpointAuthMethodsSupported.Contains(ClientAuthenticationMethods.ClientSecretPost))
                 {
                     // Important: the credentials MUST be formURL-encoded before being base64-encoded.
                     var credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes(new StringBuilder()
@@ -109,6 +100,8 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                     context.Request.ClientId = context.Request.ClientSecret = null;
                 }
 
+                return default;
+
                 static string? EscapeDataString(string? value)
                     => value is not null ? Uri.EscapeDataString(value).Replace("%20", "+") : null;
             }

src/OpenIddict.Validation/OpenIddict.Validation.csproj

@@ -22,6 +22,10 @@ To use the validation feature on ASP.NET Core or OWIN/Katana, reference the Open
     <PackageReference Include="Microsoft.IdentityModel.Protocols" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Include="..\..\shared\OpenIddict.Extensions\*\*.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <Using Include="OpenIddict.Abstractions" />
     <Using Include="OpenIddict.Abstractions.OpenIddictConstants" Static="true" />

src/OpenIddict.Validation/OpenIddictValidationBuilder.cs

@@ -463,7 +463,7 @@ public sealed class OpenIddictValidationBuilder
 
         if (!Uri.TryCreate(address, UriKind.Absolute, out Uri? uri) || !uri.IsWellFormedOriginalString())
         {
-            throw new ArgumentException(SR.GetResourceString(SR.ID0127), nameof(address));
+            throw new ArgumentException(SR.GetResourceString(SR.ID0023), nameof(address));
         }
 
         return SetIssuer(uri);

src/OpenIddict.Validation/OpenIddictValidationConfiguration.cs

@@ -7,6 +7,7 @@
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Protocols;
 using Microsoft.IdentityModel.Tokens;
+using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 
@@ -105,28 +106,17 @@ public sealed class OpenIddictValidationConfiguration : IPostConfigureOptions<Op
 
                 if (!options.MetadataAddress.IsAbsoluteUri)
                 {
-                    var issuer = options.Issuer;
-                    if (issuer is not { IsAbsoluteUri: true })
+                    if (options.Issuer is not { IsAbsoluteUri: true })
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID0136));
                     }
 
-                    if (!string.IsNullOrEmpty(issuer.Fragment) || !string.IsNullOrEmpty(issuer.Query))
+                    if (!string.IsNullOrEmpty(options.Issuer.Fragment) || !string.IsNullOrEmpty(options.Issuer.Query))
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID0137));
                     }
 
-                    if (!issuer.OriginalString.EndsWith("/", StringComparison.Ordinal))
-                    {
-                        issuer = new Uri(issuer.OriginalString + "/", UriKind.Absolute);
-                    }
-
-                    if (options.MetadataAddress.OriginalString.StartsWith("/", StringComparison.Ordinal))
-                    {
-                        options.MetadataAddress = new Uri(options.MetadataAddress.OriginalString[1..], UriKind.Relative);
-                    }
-
-                    options.MetadataAddress = new Uri(issuer, options.MetadataAddress);
+                    options.MetadataAddress = OpenIddictHelpers.CreateAbsoluteUri(options.Issuer, options.MetadataAddress);
                 }
 
                 options.ConfigurationManager = new ConfigurationManager<OpenIddictConfiguration>(

src/OpenIddict.Validation/OpenIddictValidationEvents.cs

@@ -39,12 +39,21 @@ public static partial class OpenIddictValidationEvents
         }
 
         /// <summary>
-        /// Gets or sets the issuer address associated with the current transaction, if available.
+        /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
         /// </summary>
-        public Uri? Issuer
+        public Uri? RequestUri
         {
-            get => Transaction.Issuer;
-            set => Transaction.Issuer = value;
+            get => Transaction.RequestUri;
+            set => Transaction.RequestUri = value;
+        }
+
+        /// <summary>
+        /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+        /// </summary>
+        public Uri? BaseUri
+        {
+            get => Transaction.BaseUri;
+            set => Transaction.BaseUri = value;
         }
 
         /// <summary>

src/OpenIddict.Validation/OpenIddictValidationFactory.cs

@@ -30,7 +30,6 @@ public sealed class OpenIddictValidationFactory : IOpenIddictValidationFactory
     public ValueTask<OpenIddictValidationTransaction> CreateTransactionAsync()
         => new(new OpenIddictValidationTransaction
         {
-            Issuer = _options.CurrentValue.Issuer,
             Logger = _logger,
             Options = _options.CurrentValue
         });

src/OpenIddict.Validation/OpenIddictValidationHandlers.Discovery.cs

@@ -203,7 +203,8 @@ public static partial class OpenIddictValidationHandlers
                     return default;
                 }
 
-                if (context.Issuer is not null && context.Issuer != address)
+                // Ensure the issuer matches the expected value.
+                if (address != context.Options.Issuer)
                 {
                     context.Reject(
                         error: Errors.ServerError,
@@ -325,7 +326,7 @@ public static partial class OpenIddictValidationHandlers
             /// </summary>
             public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
                 = OpenIddictValidationHandlerDescriptor.CreateBuilder<HandleConfigurationResponseContext>()
-                    .UseSingletonHandler<ExtractIntrospectionEndpoint>()
+                    .UseSingletonHandler<ExtractIntrospectionEndpointClientAuthenticationMethods>()
                     .SetOrder(ExtractIntrospectionEndpoint.Descriptor.Order + 1_000)
                     .SetType(OpenIddictValidationHandlerType.BuiltIn)
                     .Build();

src/OpenIddict.Validation/OpenIddictValidationHandlers.Introspection.cs

@@ -317,7 +317,8 @@ public static partial class OpenIddictValidationHandlers
                         return default;
                     }
 
-                    if (context.Issuer is not null && context.Issuer != uri)
+                    // Ensure the issuer matches the expected value.
+                    if (uri != context.Configuration.Issuer)
                     {
                         context.Reject(
                             error: Errors.ServerError,
@@ -426,7 +427,7 @@ public static partial class OpenIddictValidationHandlers
                 // to be valid, as it is guarded against unknown values by the ValidateIssuer handler.
                 var issuer = (string?) context.Response[Claims.Issuer] ??
                     context.Configuration.Issuer?.AbsoluteUri ??
-                    context.Issuer?.AbsoluteUri ?? ClaimsIdentity.DefaultIssuer;
+                    context.BaseUri?.AbsoluteUri ?? ClaimsIdentity.DefaultIssuer;
 
                 foreach (var parameter in context.Response.GetParameters())
                 {

src/OpenIddict.Validation/OpenIddictValidationHandlers.Protection.cs

@@ -63,8 +63,12 @@ public static partial class OpenIddictValidationHandlers
                 // OpenID Connect server configuration (that can be static or retrieved using discovery).
                 var parameters = context.Options.TokenValidationParameters.Clone();
 
-                parameters.ValidIssuers ??= context.Configuration.Issuer switch
+                // If the issuer was not explicitly set, assume the authorization server
+                // is located in the same application as the component validating tokens.
+                parameters.ValidIssuers ??= (context.Configuration.Issuer ?? context.BaseUri) switch
                 {
+                    // Note: the issuer may be null at this point (e.g when validating a token
+                    // issued by a local authorization server outside a request context).
                     null => null,
 
                     // If the issuer URI doesn't contain any path/query/fragment, allow both http://www.fabrikam.com

src/OpenIddict.Validation/OpenIddictValidationHandlers.cs

@@ -60,16 +60,8 @@ public static partial class OpenIddictValidationHandlers
                 throw new ArgumentNullException(nameof(context));
             }
 
-            var configuration = await context.Options.ConfigurationManager.GetConfigurationAsync(default) ??
+            context.Configuration = await context.Options.ConfigurationManager.GetConfigurationAsync(default) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
-
-            // Ensure the issuer resolved from the configuration matches the expected value.
-            if (context.Options.Issuer is not null && configuration.Issuer != context.Options.Issuer)
-            {
-                throw new InvalidOperationException(SR.GetResourceString(SR.ID0307));
-            }
-
-            context.Configuration = configuration;
         }
     }
 

src/OpenIddict.Validation/OpenIddictValidationService.cs

@@ -8,6 +8,7 @@ using System.Diagnostics;
 using System.Security.Claims;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
@@ -48,12 +49,17 @@ public sealed class OpenIddictValidationService
         // can be disposed of asynchronously if it implements IAsyncDisposable.
         try
         {
+            var options = _provider.GetRequiredService<IOptionsMonitor<OpenIddictValidationOptions>>();
+            var configuration = await options.CurrentValue.ConfigurationManager.GetConfigurationAsync(default) ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
+
             var dispatcher = scope.ServiceProvider.GetRequiredService<IOpenIddictValidationDispatcher>();
             var factory = scope.ServiceProvider.GetRequiredService<IOpenIddictValidationFactory>();
             var transaction = await factory.CreateTransactionAsync();
 
             var context = new ValidateTokenContext(transaction)
             {
+                Configuration = configuration,
                 Token = token,
                 ValidTokenTypes = { TokenTypeHints.AccessToken }
             };
@@ -409,6 +415,10 @@ public sealed class OpenIddictValidationService
         // can be disposed of asynchronously if it implements IAsyncDisposable.
         try
         {
+            var options = _provider.GetRequiredService<IOptionsMonitor<OpenIddictValidationOptions>>();
+            var configuration = await options.CurrentValue.ConfigurationManager.GetConfigurationAsync(default) ??
+                throw new InvalidOperationException(SR.GetResourceString(SR.ID0140));
+
             var dispatcher = scope.ServiceProvider.GetRequiredService<IOpenIddictValidationDispatcher>();
             var factory = scope.ServiceProvider.GetRequiredService<IOpenIddictValidationFactory>();
             var transaction = await factory.CreateTransactionAsync();
@@ -426,6 +436,7 @@ public sealed class OpenIddictValidationService
                 var context = new PrepareIntrospectionRequestContext(transaction)
                 {
                     Address = address,
+                    Configuration = configuration,
                     Request = request,
                     Token = token,
                     TokenTypeHint = hint
@@ -448,6 +459,7 @@ public sealed class OpenIddictValidationService
                 var context = new ApplyIntrospectionRequestContext(transaction)
                 {
                     Address = address,
+                    Configuration = configuration,
                     Request = request
                 };
 
@@ -470,6 +482,7 @@ public sealed class OpenIddictValidationService
                 var context = new ExtractIntrospectionResponseContext(transaction)
                 {
                     Address = address,
+                    Configuration = configuration,
                     Request = request
                 };
 
@@ -494,6 +507,7 @@ public sealed class OpenIddictValidationService
                 var context = new HandleIntrospectionResponseContext(transaction)
                 {
                     Address = address,
+                    Configuration = configuration,
                     Request = request,
                     Response = response,
                     Token = token

src/OpenIddict.Validation/OpenIddictValidationTransaction.cs

@@ -21,9 +21,14 @@ public sealed class OpenIddictValidationTransaction
     public OpenIddictValidationEndpointType EndpointType { get; set; }
 
     /// <summary>
-    /// Gets or sets the issuer address associated with the current transaction, if available.
+    /// Gets or sets the request <see cref="Uri"/> of the current transaction, if available.
     /// </summary>
-    public Uri? Issuer { get; set; }
+    public Uri? RequestUri { get; set; }
+
+    /// <summary>
+    /// Gets or sets the base <see cref="Uri"/> of the host, if available.
+    /// </summary>
+    public Uri? BaseUri { get; set; }
 
     /// <summary>
     /// Gets or sets the logger associated with the current request.

test/OpenIddict.Server.AspNetCore.IntegrationTests/OpenIddictServerAspNetCoreIntegrationTests.cs

@@ -4,7 +4,6 @@
  * the license and the contributors participating to this project.
  */
 
-using System.Diagnostics.CodeAnalysis;
 using System.Security.Claims;
 using System.Text.Json;
 using Microsoft.AspNetCore.Authentication;
@@ -18,7 +17,6 @@ using Microsoft.Extensions.Logging;
 using OpenIddict.Server.IntegrationTests;
 using Xunit;
 using Xunit.Abstractions;
-using static OpenIddict.Server.AspNetCore.OpenIddictServerAspNetCoreHandlers;
 using static OpenIddict.Server.OpenIddictServerEvents;
 using static OpenIddict.Server.OpenIddictServerHandlers.Protection;
 
@@ -260,410 +258,6 @@ public partial class OpenIddictServerAspNetCoreIntegrationTests : OpenIddictServ
         Assert.Equal("custom_error_uri", response.ErrorUri);
     }
 
-    [Theory]
-    [InlineData("/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/connect/authorize/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/AUTHORIZE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/authorize/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/AUTHORIZE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.well-known/openid-configuration/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/openid-configuration/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.well-known/jwks/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/jwks/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("/connect/device/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/DEVICE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/device/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/DEVICE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/connect/introspect/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/INTROSPECT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/introspect/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/INTROSPECT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/connect/logout/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/LOGOUT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/logout/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/LOGOUT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/connect/revoke/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/REVOKE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/revoke/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/REVOKE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("/connect/token/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/TOKEN/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/token/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/TOKEN/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/connect/userinfo/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/USERINFO/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/userinfo/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/USERINFO/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/connect/verification/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/VERIFICATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/verification/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/VERIFICATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    public async Task ProcessRequest_MatchesCorrespondingRelativeEndpoint(string path, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                }));
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(path, new OpenIddictRequest());
-    }
-
-    [Theory]
-    [InlineData("https://localhost/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost:443/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost:443/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://fabrikam.com/connect/authorize", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/authorize", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost:443/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost:443/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://fabrikam.com/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost:443/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost:443/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://fabrikam.com/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost:443/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost:443/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://fabrikam.com/connect/device", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/device/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/device", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/device/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost:443/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost:443/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://fabrikam.com/connect/introspect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/introspect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost:443/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost:443/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://fabrikam.com/connect/logout", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/logout/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/logout", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/logout/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost:443/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost:443/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://fabrikam.com/connect/revoke", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/revoke", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost:443/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost:443/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://fabrikam.com/connect/token", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/token/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/token", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/token/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost:443/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost:443/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://fabrikam.com/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost:443/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost:443/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://fabrikam.com/connect/verification", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/verification/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/verification", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/verification/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
-    public async Task ProcessRequest_MatchesCorrespondingAbsoluteEndpoint(string path, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.SetAuthorizationEndpointUris("https://localhost/connect/authorize")
-                   .SetConfigurationEndpointUris("https://localhost/.well-known/openid-configuration")
-                   .SetCryptographyEndpointUris("https://localhost/.well-known/jwks")
-                   .SetDeviceEndpointUris("https://localhost/connect/device")
-                   .SetIntrospectionEndpointUris("https://localhost/connect/introspect")
-                   .SetLogoutEndpointUris("https://localhost/connect/logout")
-                   .SetRevocationEndpointUris("https://localhost/connect/revoke")
-                   .SetTokenEndpointUris("https://localhost/connect/token")
-                   .SetUserinfoEndpointUris("https://localhost/connect/userinfo")
-                   .SetVerificationEndpointUris("https://localhost/connect/verification");
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                }));
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(path, new OpenIddictRequest());
-    }
-
-    [Theory]
-    [InlineData("/custom/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/custom/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/custom/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/custom/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("/custom/connect/custom", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/custom/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/custom/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/custom/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/custom/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("/custom/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/custom/connect/verification", OpenIddictServerEndpointType.Verification)]
-    public async Task ProcessRequest_AllowsOverridingEndpoint(string address, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-            {
-                builder.UseInlineHandler(context =>
-                {
-                    // Act
-                    context.EndpointType = type;
-
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                });
-
-                builder.SetOrder(InferEndpointType.Descriptor.Order + 500);
-            });
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(address, new OpenIddictRequest());
-    }
-
     [Theory]
     [InlineData("/.well-known/openid-configuration")]
     [InlineData("/.well-known/jwks")]

test/OpenIddict.Server.IntegrationTests/OpenIddictServerIntegrationTests.Authentication.cs

@@ -2552,7 +2552,7 @@ public abstract partial class OpenIddictServerIntegrationTests
     [Theory]
     [InlineData(null)]
     [InlineData("http://www.fabrikam.com/")]
-    public async Task ApplyAuthorizationResponse_SetsIssuerParameter(string issuer)
+    public async Task ApplyAuthorizationResponse_SetsIssuerParameter(string? issuer)
     {
         // Arrange
         await using var server = await CreateServerAsync(options =>
@@ -2586,7 +2586,7 @@ public abstract partial class OpenIddictServerIntegrationTests
         });
 
         // Assert
-        Assert.Equal(issuer is not null ? issuer : "http://localhost/", response.Iss);
+        Assert.Equal(!string.IsNullOrEmpty(issuer) ? issuer : "http://localhost/", response.Iss);
     }
 
     [Fact]

test/OpenIddict.Server.IntegrationTests/OpenIddictServerIntegrationTests.Discovery.cs

@@ -11,6 +11,7 @@ using Microsoft.IdentityModel.Tokens;
 using Moq;
 using Xunit;
 using static OpenIddict.Server.OpenIddictServerEvents;
+using static OpenIddict.Server.OpenIddictServerHandlers.Discovery;
 
 namespace OpenIddict.Server.IntegrationTests;
 
@@ -304,66 +305,20 @@ public abstract partial class OpenIddictServerIntegrationTests
             (string?) response[Metadata.UserinfoEndpoint]);
     }
 
-    [Theory]
-    [InlineData("https://www.fabrikam.com/tenant1", new[]
-    {
-        "path/authorization_endpoint",
-        "path/cryptography_endpoint",
-        "path/device_endpoint",
-        "path/introspection_endpoint",
-        "path/logout_endpoint",
-        "path/revocation_endpoint",
-        "path/token_endpoint",
-        "path/userinfo_endpoint"
-    })]
-    [InlineData("https://www.fabrikam.com/tenant1/", new[]
-    {
-        "path/authorization_endpoint",
-        "path/cryptography_endpoint",
-        "path/device_endpoint",
-        "path/introspection_endpoint",
-        "path/logout_endpoint",
-        "path/revocation_endpoint",
-        "path/token_endpoint",
-        "path/userinfo_endpoint"
-    })]
-    [InlineData("https://www.fabrikam.com/tenant1", new[]
-    {
-        "/path/authorization_endpoint",
-        "/path/cryptography_endpoint",
-        "/path/device_endpoint",
-        "/path/introspection_endpoint",
-        "/path/logout_endpoint",
-        "/path/revocation_endpoint",
-        "/path/token_endpoint",
-        "/path/userinfo_endpoint"
-    })]
-    [InlineData("https://www.fabrikam.com/tenant1/", new[]
-    {
-        "/path/authorization_endpoint",
-        "/path/cryptography_endpoint",
-        "/path/device_endpoint",
-        "/path/introspection_endpoint",
-        "/path/logout_endpoint",
-        "/path/revocation_endpoint",
-        "/path/token_endpoint",
-        "/path/userinfo_endpoint"
-    })]
-    public async Task HandleConfigurationRequest_RelativeEndpointsAreCorrectlyComputed(string issuer, string[] endpoints)
+    [Fact]
+    public async Task HandleConfigurationRequest_RelativeEndpointsAreCorrectlyComputed()
     {
         // Arrange
         await using var server = await CreateServerAsync(options =>
         {
-            options.SetIssuer(new Uri(issuer, UriKind.Absolute));
-
-            options.SetAuthorizationEndpointUris(endpoints[0])
-                   .SetCryptographyEndpointUris(endpoints[1])
-                   .SetDeviceEndpointUris(endpoints[2])
-                   .SetIntrospectionEndpointUris(endpoints[3])
-                   .SetLogoutEndpointUris(endpoints[4])
-                   .SetRevocationEndpointUris(endpoints[5])
-                   .SetTokenEndpointUris(endpoints[6])
-                   .SetUserinfoEndpointUris(endpoints[7]);
+            options.SetAuthorizationEndpointUris("path/authorization_endpoint")
+                   .SetCryptographyEndpointUris("path/cryptography_endpoint")
+                   .SetDeviceEndpointUris("path/device_endpoint")
+                   .SetIntrospectionEndpointUris("path/introspection_endpoint")
+                   .SetLogoutEndpointUris("path/logout_endpoint")
+                   .SetRevocationEndpointUris("path/revocation_endpoint")
+                   .SetTokenEndpointUris("path/token_endpoint")
+                   .SetUserinfoEndpointUris("path/userinfo_endpoint");
         });
 
         await using var client = await server.CreateClientAsync();
@@ -372,29 +327,58 @@ public abstract partial class OpenIddictServerIntegrationTests
         var response = await client.GetAsync("/.well-known/openid-configuration");
 
         // Assert
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/authorization_endpoint",
-            (string?) response[Metadata.AuthorizationEndpoint]);
+        Assert.Equal("http://localhost/path/authorization_endpoint", (string?) response[Metadata.AuthorizationEndpoint]);
+        Assert.Equal("http://localhost/path/cryptography_endpoint", (string?) response[Metadata.JwksUri]);
+        Assert.Equal("http://localhost/path/device_endpoint", (string?) response[Metadata.DeviceAuthorizationEndpoint]);
+        Assert.Equal("http://localhost/path/introspection_endpoint", (string?) response[Metadata.IntrospectionEndpoint]);
+        Assert.Equal("http://localhost/path/logout_endpoint", (string?) response[Metadata.EndSessionEndpoint]);
+        Assert.Equal("http://localhost/path/revocation_endpoint", (string?) response[Metadata.RevocationEndpoint]);
+        Assert.Equal("http://localhost/path/token_endpoint", (string?) response[Metadata.TokenEndpoint]);
+        Assert.Equal("http://localhost/path/userinfo_endpoint", (string?) response[Metadata.UserinfoEndpoint]);
+    }
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/cryptography_endpoint",
-            (string?) response[Metadata.JwksUri]);
+    [Fact]
+    public async Task HandleConfigurationRequest_RelativeEndpointsWithSpecificBaseUriAreCorrectlyComputed()
+    {
+        // Arrange
+        await using var server = await CreateServerAsync(options =>
+        {
+            options.SetAuthorizationEndpointUris("path/authorization_endpoint")
+                   .SetCryptographyEndpointUris("path/cryptography_endpoint")
+                   .SetDeviceEndpointUris("path/device_endpoint")
+                   .SetIntrospectionEndpointUris("path/introspection_endpoint")
+                   .SetLogoutEndpointUris("path/logout_endpoint")
+                   .SetRevocationEndpointUris("path/revocation_endpoint")
+                   .SetTokenEndpointUris("path/token_endpoint")
+                   .SetUserinfoEndpointUris("path/userinfo_endpoint");
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/device_endpoint",
-            (string?) response[Metadata.DeviceAuthorizationEndpoint]);
+            options.AddEventHandler<HandleConfigurationRequestContext>(builder =>
+            {
+                builder.UseInlineHandler(context =>
+                {
+                    context.BaseUri = new Uri("https://contoso.com/issuer");
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/introspection_endpoint",
-            (string?) response[Metadata.IntrospectionEndpoint]);
+                    return default;
+                });
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/logout_endpoint",
-            (string?) response[Metadata.EndSessionEndpoint]);
+                builder.SetOrder(AttachEndpoints.Descriptor.Order - 1);
+            });
+        });
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/revocation_endpoint",
-            (string?) response[Metadata.RevocationEndpoint]);
+        await using var client = await server.CreateClientAsync();
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/token_endpoint",
-            (string?) response[Metadata.TokenEndpoint]);
+        // Act
+        var response = await client.GetAsync("/.well-known/openid-configuration");
 
-        Assert.Equal("https://www.fabrikam.com/tenant1/path/userinfo_endpoint",
-            (string?) response[Metadata.UserinfoEndpoint]);
+        // Assert
+        Assert.Equal("https://contoso.com/issuer/path/authorization_endpoint", (string?) response[Metadata.AuthorizationEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/cryptography_endpoint", (string?) response[Metadata.JwksUri]);
+        Assert.Equal("https://contoso.com/issuer/path/device_endpoint", (string?) response[Metadata.DeviceAuthorizationEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/introspection_endpoint", (string?) response[Metadata.IntrospectionEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/logout_endpoint", (string?) response[Metadata.EndSessionEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/revocation_endpoint", (string?) response[Metadata.RevocationEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/token_endpoint", (string?) response[Metadata.TokenEndpoint]);
+        Assert.Equal("https://contoso.com/issuer/path/userinfo_endpoint", (string?) response[Metadata.UserinfoEndpoint]);
     }
 
     [Fact]

test/OpenIddict.Server.IntegrationTests/OpenIddictServerIntegrationTests.cs

@@ -33,6 +33,410 @@ public abstract partial class OpenIddictServerIntegrationTests
 
     protected ITestOutputHelper OutputHelper { get; }
 
+    [Theory]
+    [InlineData("/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/authorize", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("/connect/authorize/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/AUTHORIZE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/authorize/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/AUTHORIZE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("/.well-known/openid-configuration/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.well-known/openid-configuration/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("/.well-known/jwks/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.well-known/jwks/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/device", OpenIddictServerEndpointType.Device)]
+    [InlineData("/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
+    [InlineData("/connect/device/", OpenIddictServerEndpointType.Device)]
+    [InlineData("/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
+    [InlineData("/connect/device/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/DEVICE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/device/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/DEVICE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/introspect", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("/connect/introspect/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/INTROSPECT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/introspect/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/INTROSPECT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/logout", OpenIddictServerEndpointType.Logout)]
+    [InlineData("/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
+    [InlineData("/connect/logout/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("/connect/logout/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/LOGOUT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/logout/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/LOGOUT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/revoke", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("/connect/revoke/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/REVOKE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/revoke/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/REVOKE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/token", OpenIddictServerEndpointType.Token)]
+    [InlineData("/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
+    [InlineData("/connect/token/", OpenIddictServerEndpointType.Token)]
+    [InlineData("/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
+    [InlineData("/connect/token/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/TOKEN/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/token/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/TOKEN/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("/connect/userinfo/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/USERINFO/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/userinfo/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/USERINFO/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/verification", OpenIddictServerEndpointType.Verification)]
+    [InlineData("/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
+    [InlineData("/connect/verification/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("/connect/verification/subpath", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/VERIFICATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/connect/verification/subpath/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/CONNECT/VERIFICATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
+    public async Task ProcessRequest_MatchesCorrespondingRelativeEndpoint(string path, OpenIddictServerEndpointType type)
+    {
+        // Arrange
+        await using var server = await CreateServerAsync(options =>
+        {
+            options.EnableDegradedMode();
+
+            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<ProcessRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    // Assert
+                    Assert.Equal(type, context.EndpointType);
+
+                    return default;
+                }));
+        });
+
+        await using var client = await server.CreateClientAsync();
+
+        // Act
+        await client.PostAsync(path, new OpenIddictRequest());
+    }
+
+    [Theory]
+    [InlineData("https://localhost/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:443/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:443/connect", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:443/connect/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/authorize", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("https://localhost/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("https://localhost:443/connect/authorize", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("https://localhost:443/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("https://fabrikam.com/connect/authorize", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/authorize", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("https://localhost/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("https://localhost:443/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("https://localhost:443/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("https://fabrikam.com/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("https://localhost/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("https://localhost:443/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("https://localhost:443/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("https://fabrikam.com/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/device", OpenIddictServerEndpointType.Device)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
+    [InlineData("https://localhost/connect/device/", OpenIddictServerEndpointType.Device)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
+    [InlineData("https://localhost:443/connect/device", OpenIddictServerEndpointType.Device)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
+    [InlineData("https://localhost:443/connect/device/", OpenIddictServerEndpointType.Device)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
+    [InlineData("https://fabrikam.com/connect/device", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/device/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/device", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/device/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/introspect", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("https://localhost/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("https://localhost:443/connect/introspect", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("https://localhost:443/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("https://fabrikam.com/connect/introspect", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/introspect", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/logout", OpenIddictServerEndpointType.Logout)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
+    [InlineData("https://localhost/connect/logout/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("https://localhost:443/connect/logout", OpenIddictServerEndpointType.Logout)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
+    [InlineData("https://localhost:443/connect/logout/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
+    [InlineData("https://fabrikam.com/connect/logout", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/logout/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/logout", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/logout/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/revoke", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("https://localhost/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("https://localhost:443/connect/revoke", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("https://localhost:443/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("https://fabrikam.com/connect/revoke", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/revoke", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/token", OpenIddictServerEndpointType.Token)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
+    [InlineData("https://localhost/connect/token/", OpenIddictServerEndpointType.Token)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
+    [InlineData("https://localhost:443/connect/token", OpenIddictServerEndpointType.Token)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
+    [InlineData("https://localhost:443/connect/token/", OpenIddictServerEndpointType.Token)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
+    [InlineData("https://fabrikam.com/connect/token", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/token/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/token", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/token/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("https://localhost/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("https://localhost:443/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("https://localhost:443/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("https://fabrikam.com/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost/connect/verification", OpenIddictServerEndpointType.Verification)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
+    [InlineData("https://localhost/connect/verification/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("https://localhost:443/connect/verification", OpenIddictServerEndpointType.Verification)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
+    [InlineData("https://localhost:443/connect/verification/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
+    [InlineData("https://fabrikam.com/connect/verification", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://fabrikam.com/connect/verification/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/verification", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("https://localhost:8888/connect/verification/", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
+    public async Task ProcessRequest_MatchesCorrespondingAbsoluteEndpoint(string path, OpenIddictServerEndpointType type)
+    {
+        // Arrange
+        await using var server = await CreateServerAsync(options =>
+        {
+            options.EnableDegradedMode();
+
+            options.SetAuthorizationEndpointUris("https://localhost/connect/authorize")
+                   .SetConfigurationEndpointUris("https://localhost/.well-known/openid-configuration")
+                   .SetCryptographyEndpointUris("https://localhost/.well-known/jwks")
+                   .SetDeviceEndpointUris("https://localhost/connect/device")
+                   .SetIntrospectionEndpointUris("https://localhost/connect/introspect")
+                   .SetLogoutEndpointUris("https://localhost/connect/logout")
+                   .SetRevocationEndpointUris("https://localhost/connect/revoke")
+                   .SetTokenEndpointUris("https://localhost/connect/token")
+                   .SetUserinfoEndpointUris("https://localhost/connect/userinfo")
+                   .SetVerificationEndpointUris("https://localhost/connect/verification");
+
+            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<ProcessRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    // Assert
+                    Assert.Equal(type, context.EndpointType);
+
+                    return default;
+                }));
+        });
+
+        await using var client = await server.CreateClientAsync();
+
+        // Act
+        await client.PostAsync(path, new OpenIddictRequest());
+    }
+
+    [Theory]
+    [InlineData("/custom/connect/authorize", OpenIddictServerEndpointType.Authorization)]
+    [InlineData("/custom/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
+    [InlineData("/custom/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
+    [InlineData("/custom/connect/device", OpenIddictServerEndpointType.Device)]
+    [InlineData("/custom/connect/custom", OpenIddictServerEndpointType.Unknown)]
+    [InlineData("/custom/connect/introspect", OpenIddictServerEndpointType.Introspection)]
+    [InlineData("/custom/connect/logout", OpenIddictServerEndpointType.Logout)]
+    [InlineData("/custom/connect/revoke", OpenIddictServerEndpointType.Revocation)]
+    [InlineData("/custom/connect/token", OpenIddictServerEndpointType.Token)]
+    [InlineData("/custom/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
+    [InlineData("/custom/connect/verification", OpenIddictServerEndpointType.Verification)]
+    public async Task ProcessRequest_AllowsOverridingEndpoint(string address, OpenIddictServerEndpointType type)
+    {
+        // Arrange
+        await using var server = await CreateServerAsync(options =>
+        {
+            options.EnableDegradedMode();
+
+            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
+                builder.UseInlineHandler(context =>
+                {
+                    context.SkipRequest();
+
+                    return default;
+                }));
+
+            options.AddEventHandler<ProcessRequestContext>(builder =>
+            {
+                builder.UseInlineHandler(context =>
+                {
+                    // Act
+                    context.EndpointType = type;
+
+                    // Assert
+                    Assert.Equal(type, context.EndpointType);
+
+                    return default;
+                });
+
+                builder.SetOrder(InferEndpointType.Descriptor.Order + 500);
+            });
+        });
+
+        await using var client = await server.CreateClientAsync();
+
+        // Act
+        await client.PostAsync(address, new OpenIddictRequest());
+    }
+
     [Fact]
     public async Task ProcessAuthentication_UnknownEndpointCausesAnException()
     {

test/OpenIddict.Server.Owin.IntegrationTests/OpenIddictServerOwinIntegrationTests.cs

@@ -4,7 +4,6 @@
  * the license and the contributors participating to this project.
  */
 
-using System.Diagnostics.CodeAnalysis;
 using System.Security.Claims;
 using System.Text.Json;
 using Microsoft.Extensions.DependencyInjection;
@@ -18,7 +17,6 @@ using Xunit;
 using Xunit.Abstractions;
 using static OpenIddict.Server.OpenIddictServerEvents;
 using static OpenIddict.Server.OpenIddictServerHandlers.Protection;
-using static OpenIddict.Server.Owin.OpenIddictServerOwinHandlers;
 
 namespace OpenIddict.Server.Owin.IntegrationTests;
 
@@ -245,410 +243,6 @@ public partial class OpenIddictServerOwinIntegrationTests : OpenIddictServerInte
         Assert.Equal("custom_error_uri", response.ErrorUri);
     }
 
-    [Theory]
-    [InlineData("/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/connect/authorize/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/AUTHORIZE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/authorize/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/AUTHORIZE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/.well-known/openid-configuration/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/openid-configuration/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/OPENID-CONFIGURATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/.well-known/jwks/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.well-known/jwks/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/.WELL-KNOWN/JWKS/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("/connect/device/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/DEVICE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/device/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/DEVICE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/connect/introspect/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/INTROSPECT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/introspect/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/INTROSPECT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/connect/logout/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/LOGOUT/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/logout/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/LOGOUT/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/connect/revoke/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/REVOKE/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/revoke/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/REVOKE/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("/connect/token/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/TOKEN/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/token/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/TOKEN/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/connect/userinfo/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/USERINFO/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/userinfo/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/USERINFO/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("/connect/verification/subpath", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/VERIFICATION/SUBPATH", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/connect/verification/subpath/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/CONNECT/VERIFICATION/SUBPATH/", OpenIddictServerEndpointType.Unknown)]
-    public async Task ProcessRequest_MatchesCorrespondingRelativeEndpoint(string path, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                }));
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(path, new OpenIddictRequest());
-    }
-
-    [Theory]
-    [InlineData("https://localhost/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/connect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:443/connect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost:443/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://localhost:443/connect/authorize/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("https://fabrikam.com/connect/authorize", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/authorize", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/authorize/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/AUTHORIZE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost:443/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://localhost:443/.well-known/openid-configuration/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("https://fabrikam.com/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/openid-configuration", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/openid-configuration/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/OPENID-CONFIGURATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost:443/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://localhost:443/.well-known/jwks/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("HTTPS://LOCALHOST:443/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("https://fabrikam.com/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/jwks", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/.well-known/jwks/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/.WELL-KNOWN/JWKS/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost:443/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://localhost:443/connect/device/", OpenIddictServerEndpointType.Device)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/DEVICE/", OpenIddictServerEndpointType.Device)]
-    [InlineData("https://fabrikam.com/connect/device", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/device/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/device", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/device/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/DEVICE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost:443/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://localhost:443/connect/introspect/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("https://fabrikam.com/connect/introspect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/introspect", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/introspect/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/INTROSPECT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost:443/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://localhost:443/connect/logout/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Logout)]
-    [InlineData("https://fabrikam.com/connect/logout", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/logout/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/logout", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/logout/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/LOGOUT/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost:443/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://localhost:443/connect/revoke/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/REVOKE/", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("https://fabrikam.com/connect/revoke", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/revoke", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/revoke/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/REVOKE/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost:443/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://localhost:443/connect/token/", OpenIddictServerEndpointType.Token)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/TOKEN/", OpenIddictServerEndpointType.Token)]
-    [InlineData("https://fabrikam.com/connect/token", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/token/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/token", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/token/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/TOKEN/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost:443/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://localhost:443/connect/userinfo/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/USERINFO/", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("https://fabrikam.com/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/userinfo", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/userinfo/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/USERINFO/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost:443/connect/verification", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://localhost:443/connect/verification/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("HTTPS://LOCALHOST:443/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Verification)]
-    [InlineData("https://fabrikam.com/connect/verification", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://fabrikam.com/connect/verification/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://FABRIKAM.COM/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/verification", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("https://localhost:8888/connect/verification/", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("HTTPS://LOCALHOST:8888/CONNECT/VERIFICATION/", OpenIddictServerEndpointType.Unknown)]
-    public async Task ProcessRequest_MatchesCorrespondingAbsoluteEndpoint(string path, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.SetAuthorizationEndpointUris("https://localhost/connect/authorize")
-                   .SetConfigurationEndpointUris("https://localhost/.well-known/openid-configuration")
-                   .SetCryptographyEndpointUris("https://localhost/.well-known/jwks")
-                   .SetDeviceEndpointUris("https://localhost/connect/device")
-                   .SetIntrospectionEndpointUris("https://localhost/connect/introspect")
-                   .SetLogoutEndpointUris("https://localhost/connect/logout")
-                   .SetRevocationEndpointUris("https://localhost/connect/revoke")
-                   .SetTokenEndpointUris("https://localhost/connect/token")
-                   .SetUserinfoEndpointUris("https://localhost/connect/userinfo")
-                   .SetVerificationEndpointUris("https://localhost/connect/verification");
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                }));
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(path, new OpenIddictRequest());
-    }
-
-    [Theory]
-    [InlineData("/custom/connect/authorize", OpenIddictServerEndpointType.Authorization)]
-    [InlineData("/custom/.well-known/openid-configuration", OpenIddictServerEndpointType.Configuration)]
-    [InlineData("/custom/.well-known/jwks", OpenIddictServerEndpointType.Cryptography)]
-    [InlineData("/custom/connect/device", OpenIddictServerEndpointType.Device)]
-    [InlineData("/custom/connect/custom", OpenIddictServerEndpointType.Unknown)]
-    [InlineData("/custom/connect/introspect", OpenIddictServerEndpointType.Introspection)]
-    [InlineData("/custom/connect/logout", OpenIddictServerEndpointType.Logout)]
-    [InlineData("/custom/connect/revoke", OpenIddictServerEndpointType.Revocation)]
-    [InlineData("/custom/connect/token", OpenIddictServerEndpointType.Token)]
-    [InlineData("/custom/connect/userinfo", OpenIddictServerEndpointType.Userinfo)]
-    [InlineData("/custom/connect/verification", OpenIddictServerEndpointType.Verification)]
-    public async Task ProcessRequest_AllowsOverridingEndpoint(string address, OpenIddictServerEndpointType type)
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options =>
-        {
-            options.EnableDegradedMode();
-
-            options.AddEventHandler<HandleLogoutRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<HandleVerificationRequestContext>(builder =>
-                builder.UseInlineHandler(context =>
-                {
-                    context.SkipRequest();
-
-                    return default;
-                }));
-
-            options.AddEventHandler<ProcessRequestContext>(builder =>
-            {
-                builder.UseInlineHandler(context =>
-                {
-                    // Act
-                    context.EndpointType = type;
-
-                    // Assert
-                    Assert.Equal(type, context.EndpointType);
-
-                    return default;
-                });
-
-                builder.SetOrder(InferEndpointType.Descriptor.Order + 500);
-            });
-        });
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act
-        await client.PostAsync(address, new OpenIddictRequest());
-    }
-
     [Theory]
     [InlineData("/.well-known/openid-configuration")]
     [InlineData("/.well-known/jwks")]

test/OpenIddict.Validation.IntegrationTests/OpenIddictValidationIntegrationTests.cs

@@ -32,29 +32,6 @@ public abstract partial class OpenIddictValidationIntegrationTests
 
     protected ITestOutputHelper OutputHelper { get; }
 
-    [Fact]
-    public async Task ProcessAuthentication_InvalidIssuerThrowsAnException()
-    {
-        // Arrange
-        await using var server = await CreateServerAsync(options => options.Configure(options =>
-        {
-            options.ConfigurationManager = new StaticConfigurationManager<OpenIddictConfiguration>(new()
-            {
-                Issuer = new Uri("https://fabrikam.com/")
-            });
-        }));
-
-        await using var client = await server.CreateClientAsync();
-
-        // Act and assert
-        var exception = await Assert.ThrowsAsync<InvalidOperationException>(delegate
-        {
-            return client.PostAsync("/authenticate", new OpenIddictRequest());
-        });
-
-        Assert.Equal(SR.GetResourceString(SR.ID0307), exception.Message);
-    }
-
     [Fact]
     public async Task ProcessAuthentication_EvalutesCorrectValidatedTokens()
     {