Asp.NET Core 限流控制-AspNetCoreRateLimit-技术圈

起因：

　近期项目中，提供了一些调用频率较高的api接口，需要保障服务器的稳定运行；需要对提供的接口进行限流控制。避免因客户端频繁的请求导致服务器的压力。

一、AspNetCoreRateLimit 介绍

　AspNetCoreRateLimit是一个ASP.NET Core速率限制的解决方案，旨在控制客户端根据IP地址或客户端ID向Web API或MVC应用发出的请求的速率。AspNetCoreRateLimit包含一个IpRateLimitMiddleware和ClientRateLimitMiddleware，每个中间件可以根据不同的场景配置限制允许IP或客户端，自定义这些限制策略，也可以将限制策略应用在每个API URL或具体的HTTP Method上。

二、AspNetCoreRateLimit使用

　由上面介绍可知AspNetCoreRateLimit支持了两种方式：基于客户端IP（IpRateLimitMiddleware）和客户端ID（ClientRateLimitMiddleware）速率限制 接下来就分别说明使用方式

　添加Nuget包引用：

 Install-Package AspNetCoreRateLimit

基于客户端IP速率限制

　　1、修改Startup.cs中方法：

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }// This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        //需要从加载配置文件appsettings.json
        services.AddOptions();
        //需要存储速率限制计算器和ip规则
        services.AddMemoryCache();

        //从appsettings.json中加载常规配置，IpRateLimiting与配置文件中节点对应
        services.Configure<IpRateLimitOptions>(Configuration.GetSection("IpRateLimiting"));

        //从appsettings.json中加载Ip规则
        services.Configure<IpRateLimitPolicies>(Configuration.GetSection("IpRateLimitPolicies"));

        //注入计数器和规则存储
        services.AddSingleton<IIpPolicyStore, MemoryCacheIpPolicyStore>();
        services.AddSingleton<IRateLimitCounterStore, MemoryCacheRateLimitCounterStore>();

        services.AddControllers();

        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        //配置（解析器、计数器密钥生成器）
        services.AddSingleton<IRateLimitConfiguration, RateLimitConfiguration>();

        //Other Code
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        //Other Code

        app.UseRouting();

        app.UseAuthorization();
　　　　　//启用客户端IP限制速率
        app.UseIpRateLimiting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

　　2、在appsettings.json中添加通用配置项节点：（IpRateLimiting节点与Startup中取的节点对应）

"IpRateLimiting": {
  //false，则全局将应用限制，并且仅应用具有作为端点的规则*。例如，如果您设置每秒5次调用的限制，则对任何端点的任何HTTP调用都将计入该限制
  //true， 则限制将应用于每个端点，如{HTTP_Verb}{PATH}。例如，如果您为*:/api/values客户端设置每秒5个呼叫的限制，
  "EnableEndpointRateLimiting": false,
  //false，拒绝的API调用不会添加到调用次数计数器上;如 客户端每秒发出3个请求并且您设置了每秒一个调用的限制，则每分钟或每天计数器等其他限制将仅记录第一个调用，即成功的API调用。如果您希望被拒绝的API调用计入其他时间的显示（分钟，小时等）
  //，则必须设置StackBlockedRequests为true。
  "StackBlockedRequests": false,
  //Kestrel 服务器背后是一个反向代理，如果你的代理服务器使用不同的页眉然后提取客户端IP X-Real-IP使用此选项来设置
  "RealIpHeader": "X-Real-IP",
  //取白名单的客户端ID。如果此标头中存在客户端ID并且与ClientWhitelist中指定的值匹配，则不应用速率限制。
  "ClientIdHeader": "X-ClientId",
  //限制状态码
  "HttpStatusCode": 429,
  ////IP白名单:支持Ip v4和v6 
  //"IpWhitelist": [ "127.0.0.1", "::1/10", "192.168.0.0/24" ],
  ////端点白名单
  //"EndpointWhitelist": [ "get:/api/license", "*:/api/status" ],
  ////客户端白名单
  //"ClientWhitelist": [ "dev-id-1", "dev-id-2" ],
  //通用规则
  "GeneralRules": [
    {
      //端点路径
      "Endpoint": "*",
      //时间段，格式：{数字}{单位}；可使用单位：s, m, h, d
      "Period": "1s",
      //限制
      "Limit": 2
    },
　　 //15分钟只能调用100次
    {"Endpoint": "*","Period": "15m","Limit": 100},
　　 //12H只能调用1000
    {"Endpoint": "*","Period": "12h","Limit": 1000},
　　 //7天只能调用10000次
    {"Endpoint": "*","Period": "7d","Limit": 10000}
  ]
}

　　配置节点已添加相应注释信息。

　　规则设置格式：　　　

端点格式：{HTTP_Verb}:{PATH}，您可以使用asterix符号来定位任何HTTP谓词。

期间格式：{INT}{PERIOD_TYPE}，您可以使用以下期间类型之一：s, m, h, d。

限制格式：{LONG}

　　3、特点Ip限制规则设置，在appsettings.json中添加 IP规则配置节点

"IpRateLimitPolicies": {
  //ip规则
  "IpRules": [
    {
      //IP
      "Ip": "84.247.85.224",
      //规则内容
      "Rules": [
        //1s请求10次
        {"Endpoint": "*","Period": "1s","Limit": 10},
        //15分钟请求200次
        {"Endpoint": "*","Period": "15m","Limit": 200}
      ]
    },
    {
      //ip支持设置多个
      "Ip": "192.168.3.22/25",
      "Rules": [
        //1秒请求5次
        {"Endpoint": "*","Period": "1s","Limit": 5},
        //15分钟请求150次
        {"Endpoint": "*","Period": "15m","Limit": 150},
        //12小时请求500次
        {"Endpoint": "*","Period": "12h","Limit": 500}
      ]
    }
  ]
}

基于客户端ID速率限制

　　1、修改Startup文件：

public void ConfigureServices(IServiceCollection services)
{
    //需要从加载配置文件appsettings.json
    services.AddOptions();

    //需要存储速率限制计算器和ip规则
    services.AddMemoryCache();

    //从appsettings.json中加载常规配置
    services.Configure<ClientRateLimitOptions>(Configuration.GetSection("IPRateLimiting"));

    //从appsettings.json中加载客户端规则
    services.Configure<ClientRateLimitPolicies>(Configuration.GetSection("ClientRateLimitPolicies"));

    //注入计数器和规则存储
    services.AddSingleton<IClientPolicyStore, MemoryCacheClientPolicyStore>();
    services.AddSingleton<IRateLimitCounterStore, MemoryCacheRateLimitCounterStore>();

    
    services.AddControllers();

        // https://github.com/aspnet/Hosting/issues/793
        // the IHttpContextAccessor service is not registered by default.
        //注入计数器和规则存储
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

        //配置（解析器、计数器密钥生成器）
        services.AddSingleton<IRateLimitConfiguration, RateLimitConfiguration>();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
        //启用客户端限制
    app.UseClientRateLimiting();

    app.UseMvc();
}

　　2、通用配置采用IP限制相同配置，添加客户端限制配置：

//客户端限制设置
"ClientRateLimitPolicies": {
  "ClientRules": [
    {
      //客户端id
      "ClientId": "client-id-1",
      "Rules": [
        {"Endpoint": "*","Period": "1s","Limit": 10},
        {"Endpoint": "*","Period": "15m","Limit": 200}
      ]
    },
    {
      "ClientId": "client-id-2",
      "Rules": [
        {"Endpoint": "*","Period": "1s","Limit": 5},
        {"Endpoint": "*","Period": "15m","Limit": 150},
        {"Endpoint": "*","Period": "12h","Limit": 500}
      ]
    }
  ]
}

　　3、调用结果：

　　　设置规则：1s只能调用一次：首次调用

　　　　调用第二次：自定义返回内容

三、其他　

运行时更新速率限制

　　　添加IpRateLimitController控制器：　　　

/// <summary>
/// IP限制控制器
/// </summary>
[Route("api/[controller]")]
[ApiController]
public class IpRateLimitController : ControllerBase
{

    private readonly IpRateLimitOptions _options;
    private readonly IIpPolicyStore _ipPolicyStore;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="optionsAccessor"></param>
    /// <param name="ipPolicyStore"></param>
    public IpRateLimitController(IOptions<IpRateLimitOptions> optionsAccessor, IIpPolicyStore ipPolicyStore)
    {
        _options = optionsAccessor.Value;
        _ipPolicyStore = ipPolicyStore;
    }

    /// <summary>
    /// 获取限制规则
    /// </summary>
    /// <returns></returns>
    [HttpGet]
    public async Task<IpRateLimitPolicies> Get()
    {
        return await _ipPolicyStore.GetAsync(_options.IpPolicyPrefix);
    }

    /// <summary>
    /// 
    /// </summary>
    [HttpPost]
    public async Task Post(IpRateLimitPolicy ipRate)
    {
        var pol = await _ipPolicyStore.GetAsync(_options.IpPolicyPrefix);
        if (ipRate != null)
        {
            pol.IpRules.Add(ipRate);
            await _ipPolicyStore.SetAsync(_options.IpPolicyPrefix, pol);
        }
    }
}

分布式部署时，需要将速率限制计算器和ip规则存储到分布式缓存中如Redis

修改注入对象

// inject counter and rules distributed cache stores
services.AddSingleton<IClientPolicyStore, DistributedCacheClientPolicyStore>();
services.AddSingleton<IRateLimitCounterStore,DistributedCacheRateLimitCounterStore>();

添加Nuget包 Microsoft.Extensions.Caching.StackExchangeRedis
在Startup中设置Redis连接

services.AddStackExchangeRedisCache(options =>
{
    options.ConfigurationOptions = new ConfigurationOptions
    {
        //silently retry in the background if the Redis connection is temporarily down
        AbortOnConnectFail = false
    };
    options.Configuration = "localhost:6379";
    options.InstanceName = "AspNetRateLimit";
});

限制时自定义相应结果：

//请求返回
    "QuotaExceededResponse": {
      "Content": "{{\"code\":429,\"msg\":\"Visit too frequently, please try again later\",\"data\":null}}",
      "ContentType": "application/json;utf-8",
      "StatusCode": 429
    },