Fixing FormatException when the login screen is posted with values other than true/false for RememberMe (Lombiq Technologies: OCORE-132)

src/OrchardCore.Modules/OrchardCore.Users/Controllers/AccountController.cs

@@ -13,7 +13,6 @@
 using Microsoft.Extensions.Localization;
 using Microsoft.Extensions.Logging;
 using OrchardCore.DisplayManagement.Notify;
-using OrchardCore.Entities;
 using OrchardCore.Modules;
 using OrchardCore.Mvc.Core.Utilities;
 using OrchardCore.Settings;

src/OrchardCore.Modules/OrchardCore.Users/Services/SafeBoolModelBinder.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Localization;
+using OrchardCore.Users.ViewModels;
+
+namespace OrchardCore.Users.Services;
+
+/// <summary>
+/// Model binder to produce a validation error when a Boolean field contains a value that's not a valid bool. The
+/// default model binder would throw a <see cref="FormatException"/>. That's an issue for <see
+/// cref="LoginViewModel.RememberMe"/> that can get invalid values from automated cracking attempts.
+/// </summary>
+internal class SafeBoolModelBinder : IModelBinder
+{
+    public Task BindModelAsync(ModelBindingContext bindingContext)
+    {
+        ArgumentNullException.ThrowIfNull(nameof(bindingContext));
+
+        var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
+
+        if (valueProviderResult == ValueProviderResult.None)
+        {
+            return Task.CompletedTask;
+        }
+
+        if (bool.TryParse(valueProviderResult.FirstValue, out bool result))
+        {
+            bindingContext.Result = ModelBindingResult.Success(result);
+            return Task.CompletedTask;
+        }
+
+        var localizer = bindingContext.HttpContext.RequestServices.GetService<IStringLocalizer<SafeBoolModelBinder>>();
+
+        bindingContext.ModelState.TryAddModelError(bindingContext.ModelName, localizer["Invalid Boolean value."]);
+
+        return Task.CompletedTask;
+    }
+}

src/OrchardCore.Modules/OrchardCore.Users/Services/SafeBoolModelBinderProvider.cs

@@ -0,0 +1,19 @@
+using System;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+
+namespace OrchardCore.Users.Services;
+
+internal class SafeBoolModelBinderProvider : IModelBinderProvider
+{
+    public IModelBinder GetBinder(ModelBinderProviderContext context)
+    {
+        ArgumentNullException.ThrowIfNull(context, nameof(context));
+
+        if (context.Metadata.ModelType == typeof(bool))
+        {
+            return new SafeBoolModelBinder();
+        }
+
+        return null;
+    }
+}

src/OrchardCore.Modules/OrchardCore.Users/Startup.cs

@@ -17,8 +17,8 @@
 using OrchardCore.Admin.Models;
 using OrchardCore.Data;
 using OrchardCore.Data.Migration;
-using OrchardCore.DisplayManagement.Descriptors;
 using OrchardCore.Deployment;
+using OrchardCore.DisplayManagement.Descriptors;
 using OrchardCore.DisplayManagement.Handlers;
 using OrchardCore.DisplayManagement.Theming;
 using OrchardCore.Environment.Commands;
@@ -258,6 +258,14 @@ public override void ConfigureServices(IServiceCollection services)
 
             services.AddScoped<CustomUserSettingsService>();
             services.AddRecipeExecutionStep<CustomUserSettingsStep>();
+
+            // When the value of LoginViewModel.RememberMe is set to anything else than "true" or "false" by the
+            // client, which is the case with automated cracking attempts, then we'd get a FormatException from the
+            // default model binder.
+            services.AddMvc(options =>
+            {
+                options.ModelBinderProviders.Insert(0, new SafeBoolModelBinderProvider());
+            });
         }
     }