Use custom handler

Author: pawel-baran-se

mnestix-proxy/Authentication/ApiKeyAuthentication/AuthorizationMiddlewareResultHandler.cs

@@ -0,0 +1,47 @@
+using Microsoft.AspNetCore.Authorization.Policy;
+using Microsoft.AspNetCore.Authorization;
+
+namespace mnestix_proxy.Authentication.ApiKeyAuthentication
+{
+    public class CustomAuthorizationMiddlewareResultHandler : IAuthorizationMiddlewareResultHandler
+    {
+        private readonly AuthorizationMiddlewareResultHandler _defaultHandler = new();
+
+        public async Task HandleAsync(RequestDelegate next, HttpContext context,
+            AuthorizationPolicy policy, PolicyAuthorizationResult authorizeResult)
+        {
+            if (authorizeResult.Forbidden)
+            {
+                context.Response.StatusCode = StatusCodes.Status403Forbidden;
+                context.Response.ContentType = "application/json";
+
+                var message = "Forbidden";
+                if (authorizeResult.AuthorizationFailure?.FailureReasons?.Any() == true)
+                {
+                    message = authorizeResult.AuthorizationFailure.FailureReasons
+                        .Select(r => r.Message)
+                        .FirstOrDefault() ?? message;
+                }
+
+                await context.Response.WriteAsJsonAsync(new { error = message });
+                return;
+            }
+
+            if (authorizeResult.Challenged)
+            {
+                context.Response.StatusCode = StatusCodes.Status401Unauthorized;
+                context.Response.ContentType = "application/json";
+
+                await context.Response.WriteAsJsonAsync(new
+                {
+                    error = "Unauthorized: You must provide valid authentication credentials."
+                });
+                return;
+            }
+
+            // Proceed normally
+            await _defaultHandler.HandleAsync(next, context, policy, authorizeResult);
+        }
+    }
+
+}

mnestix-proxy/Authentication/AuthenticationServicesRegistration.cs

@@ -1,6 +1,8 @@
 using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.Identity.Web;
 using Microsoft.IdentityModel.Tokens;
+using mnestix_proxy.Authentication.ApiKeyAuthentication;
 
 namespace mnestix_proxy.Authentication;
 
@@ -55,11 +57,7 @@ public static void AddAuthenticationServices(this IServiceCollection services, I
             services.AddMicrosoftIdentityWebApiAuthentication(configuration);
         }
         else {
-            services.AddAuthentication(options =>
-            {
-                options.DefaultAuthenticateScheme = null;
-                options.DefaultChallengeScheme = null;
-            });
+            services.AddSingleton<IAuthorizationMiddlewareResultHandler, CustomAuthorizationMiddlewareResultHandler>();
         }
     }
 }