Middleware/SimpleRateLimitMiddleware.cs - master - idalynnn/api

Middleware/SimpleRateLimitMiddleware.cs
65 строк2 KB
idalynnn
init
13 дек 2025, 05:34
13 дек 2025, 05:3444c310a
using System.Collections.Concurrent;

namespace TaskTrackerApi.Middleware;
public class SimpleRateLimitMiddleware
{
    private readonly RequestDelegate _next;
    private static readonly ConcurrentDictionary<string, Counter> Store = new();

    private readonly int _limit;
    private readonly TimeSpan _window;

    public SimpleRateLimitMiddleware(RequestDelegate next, IConfiguration config)
    {
        _next = next;
        _limit = config.GetValue<int>("RateLimit:Limit", 20);
        _window = TimeSpan.FromSeconds(config.GetValue<int>("RateLimit:WindowSeconds", 60));
    }

    public async Task Invoke(HttpContext context)
    {
        var ip = context.Connection.RemoteIpAddress?.ToString() ?? "unknown";
        var now = DateTime.UtcNow;

        var counter = Store.AddOrUpdate(
            ip,
            _ => new Counter { WindowStart = now, Count = 0 },
            (_, existing) =>
            {
                if (now - existing.WindowStart >= _window)
                {
                    existing.WindowStart = now;
                    existing.Count = 0;
                }
                return existing;
            });

        if (counter.Count >= _limit)
        {
            var retryAfter = (int)Math.Ceiling((_window - (now - counter.WindowStart)).TotalSeconds);
            if (retryAfter < 0) retryAfter = 0;

            context.Response.StatusCode = StatusCodes.Status429TooManyRequests;
            context.Response.Headers["Retry-After"] = retryAfter.ToString();
            context.Response.Headers["X-Limit-Remaining"] = "0";

            await context.Response.WriteAsJsonAsync(new
            {
                message = "Too many requests",
                retry_after_seconds = retryAfter
            });
            return;
        }

        counter.Count++;
        context.Response.Headers["X-Limit-Remaining"] = (_limit - counter.Count).ToString();

        await _next(context);
    }

    private class Counter
    {
        public DateTime WindowStart { get; set; }
        public int Count { get; set; }
    }
}