Implement client_secret_basic support for introspection

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

@@ -18,6 +18,7 @@ namespace OpenIddict.Validation.SystemNetHttp
                  * Configuration request processing:
                  */
                 PrepareGetHttpRequest<PrepareConfigurationRequestContext>.Descriptor,
+                AttachQueryStringParameters<PrepareConfigurationRequestContext>.Descriptor,
                 SendHttpRequest<ApplyConfigurationRequestContext>.Descriptor,
 
                 /*
@@ -29,6 +30,7 @@ namespace OpenIddict.Validation.SystemNetHttp
                  * Cryptography request processing:
                  */
                 PrepareGetHttpRequest<PrepareCryptographyRequestContext>.Descriptor,
+                AttachQueryStringParameters<PrepareCryptographyRequestContext>.Descriptor,
                 SendHttpRequest<ApplyCryptographyRequestContext>.Descriptor,
 
                 /*

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

@@ -4,8 +4,16 @@
  * the license and the contributors participating to this project.
  */
 
+using System;
 using System.Collections.Immutable;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Text;
+using System.Threading.Tasks;
+using JetBrains.Annotations;
+using static OpenIddict.Abstractions.OpenIddictConstants;
 using static OpenIddict.Validation.OpenIddictValidationEvents;
+using static OpenIddict.Validation.SystemNetHttp.OpenIddictValidationSystemNetHttpHandlerFilters;
 
 namespace OpenIddict.Validation.SystemNetHttp
 {
@@ -18,12 +26,86 @@ namespace OpenIddict.Validation.SystemNetHttp
                  * Introspection request processing:
                  */
                 PreparePostHttpRequest<PrepareIntrospectionRequestContext>.Descriptor,
+                AttachBasicAuthenticationCredentials.Descriptor,
+                AttachFormParameters<PrepareIntrospectionRequestContext>.Descriptor,
                 SendHttpRequest<ApplyIntrospectionRequestContext>.Descriptor,
 
                 /*
                  * Introspection response processing:
                  */
                 ExtractJsonHttpResponse<ExtractIntrospectionResponseContext>.Descriptor);
+
+            /// <summary>
+            /// Contains the logic responsible of attaching the client credentials to the HTTP Authorization header.
+            /// </summary>
+            public class AttachBasicAuthenticationCredentials : IOpenIddictValidationHandler<PrepareIntrospectionRequestContext>
+            {
+                /// <summary>
+                /// Gets the default descriptor definition assigned to this handler.
+                /// </summary>
+                public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
+                    = OpenIddictValidationHandlerDescriptor.CreateBuilder<PrepareIntrospectionRequestContext>()
+                        .AddFilter<RequireHttpMetadataAddress>()
+                        .UseSingletonHandler<AttachBasicAuthenticationCredentials>()
+                        .SetOrder(AttachFormParameters<PrepareIntrospectionRequestContext>.Descriptor.Order - 1000)
+                        .Build();
+
+                public async ValueTask HandleAsync([NotNull] PrepareIntrospectionRequestContext context)
+                {
+                    if (context == null)
+                    {
+                        throw new ArgumentNullException(nameof(context));
+                    }
+
+                    // This handler only applies to System.Net.Http requests. If the HTTP request cannot be resolved,
+                    // this may indicate that the request was incorrectly processed by another client stack.
+                    var request = context.Transaction.GetHttpRequestMessage();
+                    if (request == null)
+                    {
+                        throw new InvalidOperationException("The System.Net.Http request cannot be resolved.");
+                    }
+
+                    var configuration = await context.Options.ConfigurationManager.GetConfigurationAsync(default) ??
+                        throw new InvalidOperationException("An unknown error occurred while retrieving the server configuration.");
+
+                    // The OAuth 2.0 specification recommends sending the client credentials using basic authentication.
+                    // However, this authentication method is known to have compatibility issues with how the
+                    // client credentials are encoded, that MUST be formURL-encoded before being base64-encoded.
+                    // To guarantee that the OpenIddict validation handler can be used with servers implementing
+                    // non-standard encoding, the client_secret_post is always preferred when it's explicitly
+                    // listed as a supported client authentication method for the introspection endpoint.
+                    // If client_secret_post is not listed or if the server returned an empty methods list,
+                    // client_secret_basic is always used, as it MUST be supported by all OAuth 2.0 servers.
+                    //
+                    // 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))
+                    {
+                        var builder = new StringBuilder()
+                            .Append(EscapeDataString(context.Request.ClientId))
+                            .Append(':')
+                            .Append(EscapeDataString(context.Request.ClientSecret));
+
+                        var credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes(builder.ToString()));
+
+                        // Attach the authorization header containing the client credentials to the HTTP request.
+                        request.Headers.Authorization = new AuthenticationHeaderValue(Schemes.Basic, credentials);
+
+                        // Remove the client credentials from the request.
+                        context.Request.ClientId = context.Request.ClientSecret = null;
+                    }
+
+                    static string EscapeDataString(string value)
+                    {
+                        if (string.IsNullOrEmpty(value))
+                        {
+                            return null;
+                        }
+
+                        return Uri.EscapeDataString(value).Replace("%20", "+");
+                    }
+                }
+            }
         }
     }
 }

src/OpenIddict.Validation.SystemNetHttp/OpenIddictValidationSystemNetHttpHandlers.cs

@@ -40,7 +40,73 @@ namespace OpenIddict.Validation.SystemNetHttp
                 = OpenIddictValidationHandlerDescriptor.CreateBuilder<TContext>()
                     .AddFilter<RequireHttpMetadataAddress>()
                     .UseSingletonHandler<PrepareGetHttpRequest<TContext>>()
-                    .SetOrder(int.MaxValue - 100_000)
+                    .SetOrder(int.MinValue + 100_000)
+                    .Build();
+
+            public ValueTask HandleAsync([NotNull] TContext context)
+            {
+                if (context == null)
+                {
+                    throw new ArgumentNullException(nameof(context));
+                }
+
+                var request = new HttpRequestMessage(HttpMethod.Get, context.Address);
+                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+                request.Headers.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
+
+                // Store the HttpRequestMessage in the transaction properties.
+                context.Transaction.Properties[typeof(HttpRequestMessage).FullName] = request;
+
+                return default;
+            }
+        }
+
+        /// <summary>
+        /// Contains the logic responsible of preparing an HTTP POST request message.
+        /// </summary>
+        public class PreparePostHttpRequest<TContext> : IOpenIddictValidationHandler<TContext> where TContext : BaseExternalContext
+        {
+            /// <summary>
+            /// Gets the default descriptor definition assigned to this handler.
+            /// </summary>
+            public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
+                = OpenIddictValidationHandlerDescriptor.CreateBuilder<TContext>()
+                    .AddFilter<RequireHttpMetadataAddress>()
+                    .UseSingletonHandler<PreparePostHttpRequest<TContext>>()
+                    .SetOrder(PrepareGetHttpRequest<TContext>.Descriptor.Order + 1_000)
+                    .Build();
+
+            public ValueTask HandleAsync([NotNull] TContext context)
+            {
+                if (context == null)
+                {
+                    throw new ArgumentNullException(nameof(context));
+                }
+
+                var request = new HttpRequestMessage(HttpMethod.Post, context.Address);
+                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+                request.Headers.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
+
+                // Store the HttpRequestMessage in the transaction properties.
+                context.Transaction.Properties[typeof(HttpRequestMessage).FullName] = request;
+
+                return default;
+            }
+        }
+
+        /// <summary>
+        /// Contains the logic responsible of attaching the query string parameters to the HTTP request.
+        /// </summary>
+        public class AttachQueryStringParameters<TContext> : IOpenIddictValidationHandler<TContext> where TContext : BaseExternalContext
+        {
+            /// <summary>
+            /// Gets the default descriptor definition assigned to this handler.
+            /// </summary>
+            public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
+                = OpenIddictValidationHandlerDescriptor.CreateBuilder<TContext>()
+                    .AddFilter<RequireHttpMetadataAddress>()
+                    .UseSingletonHandler<AttachQueryStringParameters<TContext>>()
+                    .SetOrder(AttachFormParameters<TContext>.Descriptor.Order - 100_000)
                     .Build();
 
             public async ValueTask HandleAsync([NotNull] TContext context)
@@ -50,6 +116,14 @@ namespace OpenIddict.Validation.SystemNetHttp
                     throw new ArgumentNullException(nameof(context));
                 }
 
+                // This handler only applies to System.Net.Http requests. If the HTTP request cannot be resolved,
+                // this may indicate that the request was incorrectly processed by another client stack.
+                var request = context.Transaction.GetHttpRequestMessage();
+                if (request == null)
+                {
+                    throw new InvalidOperationException("The System.Net.Http request cannot be resolved.");
+                }
+
                 // Note: System.Net.Http doesn't expose convenient methods allowing to create
                 // query strings from existing key/value pairs. To work around this limitation,
                 // a FormUrlEncodedContent is instantiated and used to manually create the URL.
@@ -60,24 +134,19 @@ namespace OpenIddict.Validation.SystemNetHttp
                     from value in values
                     select new KeyValuePair<string, string>(parameter.Key, value));
 
-                var builder = new UriBuilder(context.Address)
+                var builder = new UriBuilder(request.RequestUri)
                 {
                     Query = await content.ReadAsStringAsync()
                 };
 
-                var request = new HttpRequestMessage(HttpMethod.Get, builder.Uri);
+                request.RequestUri = builder.Uri;
-                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
-                request.Headers.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
-
-                // Store the HttpRequestMessage in the transaction properties.
-                context.Transaction.Properties[typeof(HttpRequestMessage).FullName] = request;
             }
         }
 
         /// <summary>
-        /// Contains the logic responsible of preparing an HTTP POST request message.
+        /// Contains the logic responsible of attaching the form parameters to the HTTP request.
         /// </summary>
-        public class PreparePostHttpRequest<TContext> : IOpenIddictValidationHandler<TContext> where TContext : BaseExternalContext
+        public class AttachFormParameters<TContext> : IOpenIddictValidationHandler<TContext> where TContext : BaseExternalContext
         {
             /// <summary>
             /// Gets the default descriptor definition assigned to this handler.
@@ -85,8 +154,8 @@ namespace OpenIddict.Validation.SystemNetHttp
             public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
                 = OpenIddictValidationHandlerDescriptor.CreateBuilder<TContext>()
                     .AddFilter<RequireHttpMetadataAddress>()
-                    .UseSingletonHandler<PreparePostHttpRequest<TContext>>()
+                    .UseSingletonHandler<AttachFormParameters<TContext>>()
-                    .SetOrder(PrepareGetHttpRequest<TContext>.Descriptor.Order - 1_000)
+                    .SetOrder(int.MaxValue - 100_000)
                     .Build();
 
             public ValueTask HandleAsync([NotNull] TContext context)
@@ -96,9 +165,13 @@ namespace OpenIddict.Validation.SystemNetHttp
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                var request = new HttpRequestMessage(HttpMethod.Post, context.Address);
+                // This handler only applies to System.Net.Http requests. If the HTTP request cannot be resolved,
-                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+                // this may indicate that the request was incorrectly processed by another client stack.
-                request.Headers.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
+                var request = context.Transaction.GetHttpRequestMessage();
+                if (request == null)
+                {
+                    throw new InvalidOperationException("The System.Net.Http request cannot be resolved.");
+                }
 
                 request.Content = new FormUrlEncodedContent(
                     from parameter in context.Request.GetParameters()
@@ -107,9 +180,6 @@ namespace OpenIddict.Validation.SystemNetHttp
                     from value in values
                     select new KeyValuePair<string, string>(parameter.Key, value));
 
-                // Store the HttpRequestMessage in the transaction properties.
-                context.Transaction.Properties[typeof(HttpRequestMessage).FullName] = request;
-
                 return default;
             }
         }

src/OpenIddict.Validation/OpenIddictValidationHandlers.Discovery.cs

@@ -24,8 +24,8 @@ namespace OpenIddict.Validation
                  */
                 HandleErrorResponse<HandleConfigurationResponseContext>.Descriptor,
                 ValidateIssuer.Descriptor,
-                ExtractCryptographyEndpointUri.Descriptor,
+                ExtractCryptographyEndpoint.Descriptor,
-                ExtractIntrospectionEndpointUri.Descriptor,
+                ExtractIntrospectionEndpoint.Descriptor,
 
                 /*
                  * Cryptography response handling:
@@ -100,14 +100,14 @@ namespace OpenIddict.Validation
             /// <summary>
             /// Contains the logic responsible of extracting the JWKS endpoint address from the discovery document.
             /// </summary>
-            public class ExtractCryptographyEndpointUri : IOpenIddictValidationHandler<HandleConfigurationResponseContext>
+            public class ExtractCryptographyEndpoint : IOpenIddictValidationHandler<HandleConfigurationResponseContext>
             {
                 /// <summary>
                 /// Gets the default descriptor definition assigned to this handler.
                 /// </summary>
                 public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
                     = OpenIddictValidationHandlerDescriptor.CreateBuilder<HandleConfigurationResponseContext>()
-                        .UseSingletonHandler<ExtractCryptographyEndpointUri>()
+                        .UseSingletonHandler<ExtractCryptographyEndpoint>()
                         .SetOrder(ValidateIssuer.Descriptor.Order + 1_000)
                         .Build();
 
@@ -155,15 +155,15 @@ namespace OpenIddict.Validation
             /// <summary>
             /// Contains the logic responsible of extracting the introspection endpoint address from the discovery document.
             /// </summary>
-            public class ExtractIntrospectionEndpointUri : IOpenIddictValidationHandler<HandleConfigurationResponseContext>
+            public class ExtractIntrospectionEndpoint : IOpenIddictValidationHandler<HandleConfigurationResponseContext>
             {
                 /// <summary>
                 /// Gets the default descriptor definition assigned to this handler.
                 /// </summary>
                 public static OpenIddictValidationHandlerDescriptor Descriptor { get; }
                     = OpenIddictValidationHandlerDescriptor.CreateBuilder<HandleConfigurationResponseContext>()
-                        .UseSingletonHandler<ExtractIntrospectionEndpointUri>()
+                        .UseSingletonHandler<ExtractIntrospectionEndpoint>()
-                        .SetOrder(ExtractCryptographyEndpointUri.Descriptor.Order + 1_000)
+                        .SetOrder(ExtractCryptographyEndpoint.Descriptor.Order + 1_000)
                         .Build();
 
                 /// <summary>
@@ -192,6 +192,21 @@ namespace OpenIddict.Validation
 
                     context.Configuration.IntrospectionEndpoint = address;
 
+                    // Resolve the client authentication methods supported by the introspection endpoint, if available.
+                    if (context.Response.TryGetParameter(Metadata.IntrospectionEndpointAuthMethodsSupported, out var methods))
+                    {
+                        foreach (var method in methods.GetUnnamedParameters())
+                        {
+                            var value = (string) method;
+                            if (string.IsNullOrEmpty(value))
+                            {
+                                continue;
+                            }
+
+                            context.Configuration.IntrospectionEndpointAuthMethodsSupported.Add(value);
+                        }
+                    }
+
                     return default;
                 }
             }