Merge pull request #178 from IPdotSetAF/rate-limiter-policy-customiza…

…tion

feat: added Rate Limit Custom response option

README.md

@@ -152,6 +152,7 @@ namespace DNTCaptcha.TestWebApp
                 .UseCustomFont(Path.Combine(_env.WebRootPath, "fonts", "IRANSans(FaNum)_Bold.ttf")) // This is optional.
                 .AbsoluteExpiration(minutes: 7)
                 .RateLimiterPermitLimit(10) // for .NET 7x+, Also you need to call app.UseRateLimiter() after calling app.UseRouting().
+                .WithRateLimiterRejectResponse("RateLimit Exceeded.") //you can instead provide an object, it will automatically converted to json result.
                 .ShowThousandsSeparators(false)
                 .WithNoise(0.015f, 0.015f, 1, 0.0f)
                 .WithEncryptionKey("This is my secure key!")

src/DNTCaptcha.Core/DNTCaptchaOptions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Text.Json;
 using Microsoft.AspNetCore.Http;
 
 namespace DNTCaptcha.Core;
@@ -9,6 +10,19 @@ namespace DNTCaptcha.Core;
 /// </summary>
 public class DNTCaptchaOptions
 {
+    /// <summary>
+    ///     Its default value is `TooManyRequests.`
+    ///     '/TimeoutWindow/' will be replaced by the window time.
+    ///     '/PermitLimit/' will be replaced by the RateLimiterPermitLimit.
+    /// </summary>
+    public string? RateLimiterRejectedResponse { set; get; } = "TooManyRequests.";
+
+    /// <summary>
+    ///     Its default value is false.
+    ///     set to true for Json response.
+    /// </summary>
+    public bool? RateLimiterRejectedResponseType { set; get; } = false;
+
     /// <summary>
     ///     Its default value is `DNTCaptchaImage/[action]`
     /// </summary>
@@ -117,6 +131,34 @@ public DNTCaptchaOptions RateLimiterPermitLimit(int permitLimit)
         return this;
     }
 
+    /// <summary>
+    ///     The response that is sent to user when the captcha rate limit has exceeded.
+    ///     The default response is : `TooManyRequests.`
+    ///     '/TimeoutWindow/' will be replaced by the window time.
+    ///     '/PermitLimit/' will be replaced by the RateLimiterPermitLimit.
+    /// </summary>
+    public DNTCaptchaOptions WithRateLimiterRejectResponse(string rejectResponse)
+    {
+        RateLimiterRejectedResponse = rejectResponse;
+        RateLimiterRejectedResponseType = false;
+
+        return this;
+    }
+
+    /// <summary>
+    ///     The response that is sent to user when the captcha rate limit has exceeded.
+    ///     The default response is : `TooManyRequests.`
+    ///     '/TimeoutWindow/' will be replaced by the window time.
+    ///     '/PermitLimit/' will be replaced by the RateLimiterPermitLimit.
+    /// </summary>
+    public DNTCaptchaOptions WithRateLimiterRejectResponse(object rejectResponse)
+    {
+        RateLimiterRejectedResponse = JsonSerializer.Serialize(rejectResponse);
+        RateLimiterRejectedResponseType = true;
+
+        return this;
+    }
+
     /// <summary>
     ///     The CSS class name of the captcha's DIV.
     ///     Its default value is `dntCaptcha`.

src/DNTCaptcha.Core/DNTCaptchaRateLimiterPolicy.cs

@@ -20,6 +20,12 @@ public class DNTCaptchaRateLimiterPolicy : IRateLimiterPolicy<string>
     /// </summary>
     public const string Name = "DNTCaptcha-RateLimiter-Policy";
 
+    /// <summary>
+    ///     The response that is sent to user when rate limit has exceeded.
+    /// </summary>
+    private static string? _rejectedResponse { get; set; } = string.Empty;
+    private static bool? _rejectedResponseType { get; set; } = false;
+
     private readonly DNTCaptchaOptions _options;
 
     /// <summary>
@@ -28,17 +34,28 @@ public class DNTCaptchaRateLimiterPolicy : IRateLimiterPolicy<string>
     public DNTCaptchaRateLimiterPolicy(IOptions<DNTCaptchaOptions> options)
     {
         _options = options == null ? throw new ArgumentNullException(nameof(options)) : options.Value;
+        _rejectedResponse = _options.RateLimiterRejectedResponse;
+        if (!string.IsNullOrEmpty(_rejectedResponse))
+        {
+            _rejectedResponse = _rejectedResponse.Replace("/TimeoutWindow/", "1", StringComparison.OrdinalIgnoreCase).Replace("/PermitLimit/", _options.PermitLimit.ToString(CultureInfo.InvariantCulture), StringComparison.OrdinalIgnoreCase);
+            _rejectedResponseType = _options.RateLimiterRejectedResponseType;
+        }
     }
 
     /// <inheritdoc />
-    public Func<OnRejectedContext, CancellationToken, ValueTask>? OnRejected { get; } = (context, cancellationToken) =>
+    public Func<OnRejectedContext, CancellationToken, ValueTask>? OnRejected { get; } = async (context, cancellationToken) =>
     {
         if (context.Lease.TryGetMetadata(MetadataName.RetryAfter, out var retryAfter))
             context.HttpContext.Response.Headers.RetryAfter =
                 ((int)retryAfter.TotalSeconds).ToString(NumberFormatInfo.InvariantInfo);
 
         context.HttpContext.Response.StatusCode = StatusCodes.Status429TooManyRequests;
-        return default;
+
+        if (!string.IsNullOrEmpty(_rejectedResponse) && _rejectedResponseType != null)
+        {
+            context.HttpContext.Response.Headers.ContentType = (bool)_rejectedResponseType ? "application/json" : "text/plain";
+            await context.HttpContext.Response.WriteAsync(_rejectedResponse);
+        }
     };
 
     /// <inheritdoc />