add PoW captcha server implementation (based on capjs)

zero/Security/CaptchaOptions.cs

@@ -0,0 +1,46 @@
+using PowCapServer;
+
+namespace zero.Security;
+
+public class CaptchaOptions : PowCapConfig
+{
+  public string Endpoint { get; set; } = "/api/captcha";
+
+  public bool Enabled { get; set; } = true;
+
+  public string HiddenFieldName { get; set; } = "CaptchaToken";
+
+  public CaptchaLocalizationOptions Localization { get; set; } = CaptchaLocalizationOptions.German;
+}
+
+
+public class CaptchaLocalizationOptions : Dictionary<string, string>
+{
+  public static CaptchaLocalizationOptions English { get; } = new()
+  {
+    ["initial-state"] = "Verify you're human",
+    ["verifying-label"] = "Verifying...",
+    ["solved-label"] = "You're human",
+    ["error-label"] = "Error",
+    ["troubleshooting-label"] = "Troubleshooting",
+    ["wasm-disabled"] = "Enable WASM for significantly faster solving",
+    ["verify-aria-label"] = "Click to verify you're a human",
+    ["verifying-aria-label"] = "Verifying, please wait",
+    ["verified-aria-label"] = "Verified",
+    ["error-aria-label"] = "An error occurred, please try again",
+  };
+
+  public static CaptchaLocalizationOptions German { get; } = new()
+  {
+    ["initial-state"] = "Bestätige, dass du kein Bot bist",
+    ["verifying-label"] = "Wird überprüft...",
+    ["solved-label"] = "Erfolgreich",
+    ["error-label"] = "Fehler",
+    ["troubleshooting-label"] = "Fehlerbehebung",
+    ["wasm-disabled"] = "Aktiviere WASM für eine deutlich schnellere Lösung",
+    ["verify-aria-label"] = "Klicke, um zu bestätigen, dass du ein Mensch bist",
+    ["verifying-aria-label"] = "Wird überprüft, bitte warten",
+    ["verified-aria-label"] = "Bestätigt",
+    ["error-aria-label"] = "Ein Fehler ist aufgetreten, bitte versuche es erneut",
+  };
+}

zero/Security/CaptchaTagHelper.cs

@@ -0,0 +1,41 @@
+using System.IO;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using zero.Security;
+
+namespace zero.TagHelpers;
+
+[HtmlTargetElement("app-captcha", TagStructure = TagStructure.NormalOrSelfClosing)]
+public class CaptchaTagHelper(IOptionsMonitor<CaptchaOptions> options) : TagHelper
+{
+  [HtmlAttributeNotBound]
+  [ViewContext]
+  public ViewContext ViewContext { get; set; } = null!;
+
+  private readonly CaptchaOptions _options = options.CurrentValue;
+
+
+  public override void Process(TagHelperContext context, TagHelperOutput output)
+  {
+    if (!_options.Enabled)
+    {
+      output.SuppressOutput();
+      return;
+    }
+    output.TagName = "cap-widget";
+    output.Attributes.SetAttribute("class", "cap-widget");
+    output.Attributes.SetAttribute("data-cap-api-endpoint", _options.Endpoint);
+    output.Attributes.SetAttribute("data-cap-hidden-field-name", _options.HiddenFieldName);
+
+    string wasmFilePath =_options.Endpoint + "/cap.wasm";
+    output.PreElement.AppendHtml($"<script>window.CAP_CUSTOM_WASM_URL = '{wasmFilePath}';</script>");
+
+    foreach ((string key, string value) in _options.Localization)
+    {
+      output.Attributes.SetAttribute($"data-cap-i18n-{key}", value);
+    }
+  }
+}

zero/Security/CaptchaValidator.cs

@@ -0,0 +1,30 @@
+using FluentValidation;
+using FluentValidation.Validators;
+using PowCapServer.Abstractions;
+using zero.Validation.Validators;
+
+namespace zero.Security;
+
+public sealed class CaptchaValidator<T> : AsyncPropertyValidator<T, string>
+{
+  public override string Name => "CaptchaValidator";
+
+  protected override string GetDefaultMessageTemplate(string errorCode) => Localized(errorCode, Name);
+
+  public override async Task<bool> IsValidAsync(ValidationContext<T> context, string value, CancellationToken cancellation)
+  {
+    if (string.IsNullOrWhiteSpace(value))
+    {
+      return false;
+    }
+
+    ICaptchaService captchaService = StaticCaptchaService.Get();
+
+    if (captchaService is null)
+    {
+      return false;
+    }
+
+    return await captchaService.ValidateCaptchaTokenAsync(value, cancellation);
+  }
+}

zero/Security/StaticCaptchaService.cs

@@ -0,0 +1,16 @@
+using Microsoft.Extensions.DependencyInjection;
+using PowCapServer.Abstractions;
+
+namespace zero.Security;
+
+internal static class StaticCaptchaService
+{
+  private static IServiceProvider Services { get; set; }
+
+  public static void Configure(IServiceProvider services)
+  {
+    Services = services;
+  }
+
+  public static ICaptchaService Get() => Services.GetRequiredService<ICaptchaService>();
+}

zero/Security/ValidatorExtensions.cs

@@ -0,0 +1,15 @@
+using FluentValidation;
+using zero.Security;
+
+namespace zero.Validation;
+
+public static partial class ValidatorExtensions
+{
+  /// <summary>
+  /// Validates a captcha token
+  /// </summary>
+  public static IRuleBuilderOptions<T, string> Captcha<T>(this IRuleBuilder<T, string> ruleBuilder)
+  {
+    return ruleBuilder.SetAsyncValidator(new CaptchaValidator<T>());
+  }
+}

zero/Security/ZeroSecurityModule.cs

@@ -0,0 +1,55 @@
+using System.IO;
+using System.Reflection;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+
+namespace zero.Security;
+
+internal class ZeroSecurityModule : ZeroModule
+{
+  public override void ConfigureServices(IServiceCollection services, IConfiguration configuration)
+  {
+    IConfigurationSection captchaSection = configuration.GetSection("Zero:Captcha");
+    services.AddOptions<CaptchaOptions>().Bind(captchaSection);
+
+    services.AddPowCapServer(options =>
+    {
+      CaptchaOptions captchaOptions = captchaSection.Get<CaptchaOptions>() ?? new CaptchaOptions();
+      options.Default = captchaOptions;
+    });
+  }
+
+  public override void Configure(IApplicationBuilder app, IEndpointRouteBuilder routes, IServiceProvider serviceProvider)
+  {
+    IOptionsMonitor<CaptchaOptions> options = serviceProvider.GetRequiredService<IOptionsMonitor<CaptchaOptions>>();
+    string endpointPrefix = options.CurrentValue.Endpoint;
+
+    app.UseRouting();
+    app.MapPowCapServer(endpointPrefix);
+    app.UseEndpoints(endpoints =>
+    {
+      endpoints.MapGet(endpointPrefix + "/cap.wasm", async context =>
+      {
+        Assembly assembly = typeof(ZeroSecurityModule).GetTypeInfo().Assembly;
+        Stream resource = assembly.GetManifestResourceStream("zero.Resources.cap_wasm_bg_0_0_6.wasm");
+
+        if (resource is null)
+        {
+          context.Response.StatusCode = StatusCodes.Status404NotFound;
+          return;
+        }
+
+        await using (resource)
+        {
+          context.Response.ContentType = "application/wasm";
+          await resource.CopyToAsync(context.Response.Body, context.RequestAborted);
+        }
+      });
+    });
+    StaticCaptchaService.Configure(serviceProvider);
+  }
+}

zero/Validation/German/FluentValidationGermanLanguage.cs

@@ -34,6 +34,7 @@ public class FluentValidationGermanLanguage
 		{ "MinimumLength_Simple", "Die Länge muss größer oder gleich {MinLength} sein." },
 		{ "MaximumLength_Simple", "Die Länge muss kleiner oder gleich {MaxLength} sein." },
 		{ "ExactLength_Simple", "Dieses Feld muss genau {MaxLength} lang sein." },
-		{ "InclusiveBetween_Simple", "Der Wert muss zwischen {From} and {To} sein." }
+		{ "InclusiveBetween_Simple", "Der Wert muss zwischen {From} and {To} sein." },
+		{ "CaptchaValidator", "Das Catpcha wurde nicht erfolgreich gelöst." }
 	};
 }

zero/Validation/ValidatorExtensions.cs

@@ -3,7 +3,7 @@ using zero.Validation.Validators;
 
 namespace zero.Validation;
 
-public static class ValidatorExtensions
+public static partial class ValidatorExtensions
 {
   /// <summary>
   /// Validate a color input as HEX (#aabbccdd or #aabbcc or #abc)

zero/ZeroBuilder.cs

@@ -9,6 +9,7 @@ using zero.Metadata;
 using zero.Mvc;
 using zero.Numbers;
 using zero.Routing;
+using zero.Security;
 
 namespace zero;
 
@@ -68,6 +69,7 @@ public class ZeroBuilder
     Modules.Add<ZeroNumberModule>();
     Modules.Add<ZeroRoutingModule>();
     Modules.Add<ZeroMetadataModule>();
+    Modules.Add<ZeroSecurityModule>();
 
     Modules.ConfigureServices(services, configuration);
 

zero/zero.csproj

@@ -16,7 +16,12 @@
     <ItemGroup>
         <PackageReference Include="Microsoft.Extensions.DependencyModel" Version="9.0.4" />
         <PackageReference Include="FluentValidation" Version="11.11.0" />
+        <PackageReference Include="PowCapServer.AspNetCore" Version="2.0.0" />
         <PackageReference Include="SixLabors.ImageSharp.Web" Version="3.2.0" />
     </ItemGroup>
 
+    <ItemGroup>
+      <EmbeddedResource Include="Resources\cap_wasm_bg_0_0_6.wasm" />
+    </ItemGroup>
+
 </Project>