从ASP.NET到.NET Core的DelegateHandler [英] DelegateHandler from ASP.NET to .NET Core

问题描述

在一个旧的asp.net项目中，我有一个实现 DelegatingHandler 的类，该类已设置为每个路由：

In an old asp.net project I have a class that implements DelegatingHandler that I set to each route:

public class AdminSecurityMessageHandler : DelegatingHandler
{
    private readonly HttpConfiguration _config;

    public AdminSecurityMessageHandler(HttpConfiguration config)
    {
        if (config == null)
        {
            throw new ArgumentNullException("config");
        }
        _config = config;
    }

    protected override Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var repository = (IUserRepository)_config.DependencyResolver.GetService(typeof(IUserRepository));
        var accessTokener = (IAccessTokener)_config.DependencyResolver.GetService(typeof(IAccessTokener));

        if (!request.Headers.Contains(AccessTokener.CallerId))
        {
            return Unauthorized(String.Empty);
        }

        var guid = request.Headers.GetValues(AccessTokener.CallerId).FirstOrDefault();
        var user = repository.GetByGuid(guid);

        if (user == null)
        {
            return Unauthorized(String.Empty);
        }

        var result = accessTokener.CheckAccessTokenHash(user.Guid, request.Headers.Authorization.Parameter);
        switch (result)
        {
            case AccessTokenCheckerResult.Invalid:
                return Unauthorized(String.Empty);
            case AccessTokenCheckerResult.Expired:
                return Unauthorized("AccessToken.Expired");
        }

        if (!user.IsAdmin)
        {
            return Unauthorized("No admin rights");
        }

        var claims = new List<Claim>();
        claims.Add(new Claim(ClaimTypes.Name, user.Id.ToString()));
        var identity = new ClaimsIdentity(claims, "custom");
        var principal = new UserPrincipal(identity, user);
        request.GetRequestContext().Principal = principal;

        return base.SendAsync(request, cancellationToken);
    }

我需要将项目移至.NET Core，但遇到了一些麻烦尝试注册时。
我可以注册这样的简单路线：

I need to move the project to .NET Core, and I have some troubles when trying to register them. I can register simple routes like this:

app.UseMvc(routes => { routes.MapWebApiRoute("DefaultApi", "api/{controller}/{id?}"); });

所以问题是我应该如何实现并设置 DelegatingHandler ？ （为每个路由设置不同的处理程序）

So the question is how should I implement and set something like DelegatingHandler from ASP.NET when I register routes in .NET Core? (Set different handler per route)

在ASP.NET中的工作方式：
在 WebApiConfig 类。

How it works in ASP.NET: Register method in WebApiConfig class.

public static void RegisterRoutes(HttpConfiguration config, HttpMessageHandler routeHandlers, HttpMessageHandler adminRouteHandlers)
{
    .......................

    config.Routes.MapHttpRoute(
        name: "FriendsAPI",
        routeTemplate: "api/users/{id}/friends/{friendId}",
        defaults: new { controller = "Friends", friendId = RouteParameter.Optional },
        constraints: null,
        handler: routeHandlers
    );


    config.Routes.MapHttpRoute(
        name: "AdminUserBlocksApi",
        routeTemplate:
            "api/admin/user-blocks/{userId}",
        defaults: new { controller = "AdminUserBlocks", userId = RouteParameter.Optional },
        constraints: null,
        handler: adminRouteHandlers
    .......................
    );
}

推荐答案

因为没有<$ Asp.Net Core 中的c $ c> DelegateHandlers ，您可以尝试创建自定义的中间件。请参见简化的中间件，您可以使用它来满足您的要求：

Since there is no DelegateHandlers in Asp.Net Core you can try to create a custom middleware. See the simplified middleware that you can use to meet your requirements:

public class AdminSecurityMiddleware
{
    private readonly RequestDelegate _next;
    IUserRepository userRepository; // IUserRepository should be registered for dependency injection in Startup.ConfigureServices

    public AdminSecurityMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        bool isAdminUserBlocksApiRoute; 
        //check for route here. As I know there is no elegant way to get name of the route since context.GetRouteData() returns null until mvc middleware is called.
        // probably you can check like this context.Request.Path.StartsWithSegments("/api/admin")

        if (isAdminUserBlocksApiRoute)
        {
            _userRepository = context.RequestServices.GetService<IUserRepository>();
            bool isUserAuthorized;
            // check here for Authorization
            if (!isUserAuthorized)
            {
                context.Response.Clear();
                context.Response.StatusCode = (int)System.Net.HttpStatusCode.Unauthorized;
                await context.Response.WriteAsync("Unauthorized");
                return;
            }

            // adding custom claims
            var identity = new ClaimsIdentity(new GenericIdentity("user.Id"), new[] { new Claim("user_id", "id") });
            context.User.AddIdentity(identity);
        }
        await _next.Invoke(context);
    }
}

然后在启动中的> mvc 中间件：

Then add it to pipeline before mvc middleware in Startup:

app.UseMiddleware<AdminSecurityMiddleware>();
app.UseMvc(routes =>
{
    ...
}

在此处

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