forked from ddrilling/AsbCloudServer
74 lines
2.9 KiB
C#
74 lines
2.9 KiB
C#
using Microsoft.AspNetCore.Http;
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using Microsoft.Extensions.Configuration;
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using System.Collections.Concurrent;
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using System.Collections.Generic;
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using System.Linq;
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using System.Threading.Tasks;
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namespace AsbCloudWebApi.Middlewares
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{
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/// <summary>
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/// This is not real middleware it`s part of PermissionsMiddlware.
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/// DO NOT register it in setup.cs as middleware.
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/// </summary>
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class UserConnectionsLimitMiddlware
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{
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private readonly int parallelRequestsToController;
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private readonly RequestDelegate next;
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private readonly byte[] responseBody;
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private readonly ConcurrentDictionary<int, ConcurrentDictionary<string, int>> stat = new ();
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private readonly IEnumerable<string>? controllerNames;
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public UserConnectionsLimitMiddlware(RequestDelegate next, IConfiguration configuration)
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{
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const int parallelRequestsToControllerDefault = 8;
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this.next = next;
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var parallelRequestsToController = configuration.GetSection("userLimits")?.GetValue<int>("parallelRequestsToController") ?? parallelRequestsToControllerDefault;
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this.parallelRequestsToController = parallelRequestsToController > 0
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? parallelRequestsToController
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: parallelRequestsToControllerDefault;
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controllerNames = configuration.GetSection("userLimits")?.GetValue<IEnumerable<string>>("controllerNames");
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var bodyText = $"<html><head><title>Too Many Requests</title></head><body><h1>Too Many Requests</h1><p>I only allow {this.parallelRequestsToController} parallel requests per user. Try again soon.</p></body></html>";
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responseBody = System.Text.Encoding.UTF8.GetBytes(bodyText);
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}
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public async Task InvokeAsync(HttpContext context, int idUser, string controllerName)
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{
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if(controllerNames?.Any(n => controllerName.StartsWith(n)) == false)
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{
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await next(context);
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return;
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}
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var userStat = stat.GetOrAdd(idUser, idUser => new());
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var count = userStat.AddOrUpdate(controllerName, 0, (k, v) => v);
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if(count + 1 < parallelRequestsToController)
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{
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try
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{
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userStat[controllerName]++;
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await next(context);
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}
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finally
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{
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userStat[controllerName]--;
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}
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}
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else
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{
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context.Response.Clear();
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context.Response.StatusCode = (int)System.Net.HttpStatusCode.TooManyRequests;
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context.Response.Headers.RetryAfter = "1000";
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context.Response.Headers.ContentType = "text/html";
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await context.Response.BodyWriter.WriteAsync(responseBody);
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}
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}
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}
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}
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