在MVC .net Core中获取域和子域

Question

如何在Startup.cs中获取MVC .net core2中的当前域和子域。我设法在MVC3和4中做到了，但我在与此相关的文档中找不到任何内容。我的启动文件如下所示：

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)
    {
        services.AddMvc();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
            app.UseBrowserLink();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
        }

        app.UseStaticFiles();

        string subdomain = //subdomain should come here
        string domain = //domain should come here

        app.UseMvc(route => CustomRouting.GetRouts(route,domain,subdomain));

    }