En un antiguo proyecto asp.net tengo una clase que implementaDelegatingHandler que configuré para cada ruta:

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);
    }

Necesito mover el proyecto a .NET Core, y tengo algunos problemas al intentar registrarlos. Puedo registrar rutas simples como esta:

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

Así que la pregunta es cómo debería implementar y establecer algo comoDelegatingHandler desde ASP.NET cuando registro rutas en .NET Core? (Establecer un controlador diferente por ruta)

Cómo funciona en ASP.NET: método de registro enWebApiConfig clase

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
    .......................
    );
}