How can I use async in actix_web middleware and return a custom HTTP status?

[OlalalalaO]

This is an authentication middleware. I want to return a 403 status directly when the permission check fails.The check_permission function is an asynchronous operation that queries Redis.

This is my code, but it is incorrect:

impl<S, B> Transform<S, ServiceRequest> for Auth
where
    S: Service<ServiceRequest, Response=ServiceResponse<B>, Error=Error>,
    S::Future: 'static,
    B: 'static,
{
    type Response = ServiceResponse<B>;
    type Error = Error;
    type Transform = AuthMiddle<S>;
    type InitError = ();
    type Future = Ready<Result<Self::Transform, Self::InitError>>;

    fn new_transform(&self, service: S) -> Self::Future {
        ready(Ok(AuthMiddle { service }))
    }
}

pub struct AuthMiddle<S> {
    service: S,
}

impl<S, B> Service<ServiceRequest> for AuthMiddle<S>
where
    S: Service<ServiceRequest, Response=ServiceResponse<B>, Error=Error>,
    S::Future: 'static,
    B: 'static,
{
    type Response = ServiceResponse<B>;
    type Error = Error;
    type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;

    forward_ready!(service);

    fn call(&self, req: ServiceRequest) -> Self::Future {
        let fut = async move {
            if check_permission(&req).await {
                self.service.call(req).await
            } else {
                let (request, _pl) = req.into_parts();
                let response = HttpResponse::Forbidden().finish().map_into_boxed_body();
                Ok(ServiceResponse::new(request, response))
            }
        };
        Box::pin(fut)
    }
}

The error is as follows:

   = note: expected enum `std::result::Result<ServiceResponse<B>, actix_web::Error>`
              found enum `std::result::Result<ServiceResponse<BoxBody>, _>`

What should I do?

[robjtede]

For your case, you'd need to leverage EitherBody.

type Response = ServiceResponse<EitherBody<B, BoxBody>>

However, the easiest way to create async middleware these days is to use middleware::from_fn from the lab (soon to graduate to the main lib). I'd recommend using this instead.