Asp .Net Core Web API Rate Limit

原文参考：

https://github.com/stefanprodan/AspNetCoreRateLimit（Code）

https://github.com/stefanprodan/AspNetCoreRateLimit/wiki （Wiki）

https://www.getpostman.com/（Http Tool）

解决思路：

Http请求时，通过Header传值（X-ClientId）判断并计数指定接口的调用次数，从而拦截超过设置上限的调用请求。其中，X-ClientId为自定义参数。

参数配置（appsettings.json e.g）：

"ClientRateLimiting": {
		"EnableEndpointRateLimiting": true,
		"StackBlockedRequests": false,
		"ClientIdHeader": "X-ClientId",
		"HttpStatusCode": 429,
		"EndpointWhitelist": [],
		"ClientWhitelist": [],
		"GeneralRules": [
			{
				"Endpoint": "get:/api/services/app/CountActivity/GetCountActivity",
				"Period": "1s",
				"Limit": 1
			}
		]
	}

服务配置（Startup.cs e.g）：

public IServiceProvider ConfigureServices(IServiceCollection services)
        {          
            services.AddOptions();            
            services.Configure<ClientRateLimitOptions>(_appConfiguration.GetSection("ClientRateLimiting"));         
            
            // inject counter and rules stores
            services.AddSingleton<IClientPolicyStore, DistributedCacheClientPolicyStore>();
            services.AddSingleton<IRateLimitCounterStore, DistributedCacheRateLimitCounterStore>();
           
        }

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{	
	app.UseClientRateLimiting();

	app.UseMvc();
}

方法重写：

对于拦截过滤有自定义需求时，可以重写ClientRateLimitMiddleware.SetIdentity方法实现

public virtual ClientRequestIdentity SetIdentity(HttpContext httpContext)
        {
            var clientId = "anon";
            if (httpContext.Request.Headers.Keys.Contains(_options.ClientIdHeader,StringComparer.CurrentCultureIgnoreCase))
            {
                clientId = httpContext.Request.Headers[_options.ClientIdHeader].First();
            }

            return new ClientRequestIdentity
            {
                Path = httpContext.Request.Path.ToString().ToLowerInvariant(),
                HttpVerb = httpContext.Request.Method.ToLowerInvariant(),
                ClientId = clientId
            };
        }