actix_web/middleware/err_handlers.rs
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//! For middleware documentation, see [`ErrorHandlers`].
use std::{
future::Future,
pin::Pin,
rc::Rc,
task::{Context, Poll},
};
use actix_service::{Service, Transform};
use ahash::AHashMap;
use futures_core::{future::LocalBoxFuture, ready};
use pin_project_lite::pin_project;
use crate::{
body::EitherBody,
dev::{ServiceRequest, ServiceResponse},
http::StatusCode,
Error, Result,
};
/// Return type for [`ErrorHandlers`] custom handlers.
pub enum ErrorHandlerResponse<B> {
/// Immediate HTTP response.
Response(ServiceResponse<EitherBody<B>>),
/// A future that resolves to an HTTP response.
Future(LocalBoxFuture<'static, Result<ServiceResponse<EitherBody<B>>, Error>>),
}
type ErrorHandler<B> = dyn Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>>;
type DefaultHandler<B> = Option<Rc<ErrorHandler<B>>>;
/// Middleware for registering custom status code based error handlers.
///
/// Register handlers with the [`ErrorHandlers::handler()`] method to register a custom error handler
/// for a given status code. Handlers can modify existing responses or create completely new ones.
///
/// To register a default handler, use the [`ErrorHandlers::default_handler()`] method. This
/// handler will be used only if a response has an error status code (400-599) that isn't covered by
/// a more specific handler (set with the [`handler()`][ErrorHandlers::handler] method). See examples
/// below.
///
/// To register a default for only client errors (400-499) or only server errors (500-599), use the
/// [`ErrorHandlers::default_handler_client()`] and [`ErrorHandlers::default_handler_server()`]
/// methods, respectively.
///
/// Any response with a status code that isn't covered by a specific handler or a default handler
/// will pass by unchanged by this middleware.
///
/// # Examples
///
/// Adding a header:
///
/// ```
/// use actix_web::{
/// dev::ServiceResponse,
/// http::{header, StatusCode},
/// middleware::{ErrorHandlerResponse, ErrorHandlers},
/// web, App, HttpResponse, Result,
/// };
///
/// fn add_error_header<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// res.response_mut().headers_mut().insert(
/// header::CONTENT_TYPE,
/// header::HeaderValue::from_static("Error"),
/// );
///
/// // body is unchanged, map to "left" slot
/// Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
/// }
///
/// let app = App::new()
/// .wrap(ErrorHandlers::new().handler(StatusCode::INTERNAL_SERVER_ERROR, add_error_header))
/// .service(web::resource("/").route(web::get().to(HttpResponse::InternalServerError)));
/// ```
///
/// Modifying response body:
///
/// ```
/// use actix_web::{
/// dev::ServiceResponse,
/// http::{header, StatusCode},
/// middleware::{ErrorHandlerResponse, ErrorHandlers},
/// web, App, HttpResponse, Result,
/// };
///
/// fn add_error_body<B>(res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// // split service response into request and response components
/// let (req, res) = res.into_parts();
///
/// // set body of response to modified body
/// let res = res.set_body("An error occurred.");
///
/// // modified bodies need to be boxed and placed in the "right" slot
/// let res = ServiceResponse::new(req, res)
/// .map_into_boxed_body()
/// .map_into_right_body();
///
/// Ok(ErrorHandlerResponse::Response(res))
/// }
///
/// let app = App::new()
/// .wrap(ErrorHandlers::new().handler(StatusCode::INTERNAL_SERVER_ERROR, add_error_body))
/// .service(web::resource("/").route(web::get().to(HttpResponse::InternalServerError)));
/// ```
///
/// Registering default handler:
///
/// ```
/// # use actix_web::{
/// # dev::ServiceResponse,
/// # http::{header, StatusCode},
/// # middleware::{ErrorHandlerResponse, ErrorHandlers},
/// # web, App, HttpResponse, Result,
/// # };
/// fn add_error_header<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// res.response_mut().headers_mut().insert(
/// header::CONTENT_TYPE,
/// header::HeaderValue::from_static("Error"),
/// );
///
/// // body is unchanged, map to "left" slot
/// Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
/// }
///
/// fn handle_bad_request<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// res.response_mut().headers_mut().insert(
/// header::CONTENT_TYPE,
/// header::HeaderValue::from_static("Bad Request Error"),
/// );
///
/// // body is unchanged, map to "left" slot
/// Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
/// }
///
/// // Bad Request errors will hit `handle_bad_request()`, while all other errors will hit
/// // `add_error_header()`. The order in which the methods are called is not meaningful.
/// let app = App::new()
/// .wrap(
/// ErrorHandlers::new()
/// .default_handler(add_error_header)
/// .handler(StatusCode::BAD_REQUEST, handle_bad_request)
/// )
/// .service(web::resource("/").route(web::get().to(HttpResponse::InternalServerError)));
/// ```
///
/// You can set default handlers for all client (4xx) or all server (5xx) errors:
///
/// ```
/// # use actix_web::{
/// # dev::ServiceResponse,
/// # http::{header, StatusCode},
/// # middleware::{ErrorHandlerResponse, ErrorHandlers},
/// # web, App, HttpResponse, Result,
/// # };
/// # fn add_error_header<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// # res.response_mut().headers_mut().insert(
/// # header::CONTENT_TYPE,
/// # header::HeaderValue::from_static("Error"),
/// # );
/// # Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
/// # }
/// # fn handle_bad_request<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
/// # res.response_mut().headers_mut().insert(
/// # header::CONTENT_TYPE,
/// # header::HeaderValue::from_static("Bad Request Error"),
/// # );
/// # Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
/// # }
/// // Bad request errors will hit `handle_bad_request()`, other client errors will hit
/// // `add_error_header()`, and server errors will pass through unchanged
/// let app = App::new()
/// .wrap(
/// ErrorHandlers::new()
/// .default_handler_client(add_error_header) // or .default_handler_server
/// .handler(StatusCode::BAD_REQUEST, handle_bad_request)
/// )
/// .service(web::resource("/").route(web::get().to(HttpResponse::InternalServerError)));
/// ```
pub struct ErrorHandlers<B> {
default_client: DefaultHandler<B>,
default_server: DefaultHandler<B>,
handlers: Handlers<B>,
}
type Handlers<B> = Rc<AHashMap<StatusCode, Box<ErrorHandler<B>>>>;
impl<B> Default for ErrorHandlers<B> {
fn default() -> Self {
ErrorHandlers {
default_client: Default::default(),
default_server: Default::default(),
handlers: Default::default(),
}
}
}
impl<B> ErrorHandlers<B> {
/// Construct new `ErrorHandlers` instance.
pub fn new() -> Self {
ErrorHandlers::default()
}
/// Register error handler for specified status code.
pub fn handler<F>(mut self, status: StatusCode, handler: F) -> Self
where
F: Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> + 'static,
{
Rc::get_mut(&mut self.handlers)
.unwrap()
.insert(status, Box::new(handler));
self
}
/// Register a default error handler.
///
/// Any request with a status code that hasn't been given a specific other handler (by calling
/// [`.handler()`][ErrorHandlers::handler]) will fall back on this.
///
/// Note that this will overwrite any default handlers previously set by calling
/// [`default_handler_client()`] or [`.default_handler_server()`], but not any set by calling
/// [`.handler()`].
///
/// [`default_handler_client()`]: ErrorHandlers::default_handler_client
/// [`.default_handler_server()`]: ErrorHandlers::default_handler_server
/// [`.handler()`]: ErrorHandlers::handler
pub fn default_handler<F>(self, handler: F) -> Self
where
F: Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> + 'static,
{
let handler = Rc::new(handler);
let handler2 = Rc::clone(&handler);
Self {
default_server: Some(handler2),
default_client: Some(handler),
..self
}
}
/// Register a handler on which to fall back for client error status codes (400-499).
pub fn default_handler_client<F>(self, handler: F) -> Self
where
F: Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> + 'static,
{
Self {
default_client: Some(Rc::new(handler)),
..self
}
}
/// Register a handler on which to fall back for server error status codes (500-599).
pub fn default_handler_server<F>(self, handler: F) -> Self
where
F: Fn(ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> + 'static,
{
Self {
default_server: Some(Rc::new(handler)),
..self
}
}
/// Selects the most appropriate handler for the given status code.
///
/// If the `handlers` map has an entry for that status code, that handler is returned.
/// Otherwise, fall back on the appropriate default handler.
fn get_handler<'a>(
status: &StatusCode,
default_client: Option<&'a ErrorHandler<B>>,
default_server: Option<&'a ErrorHandler<B>>,
handlers: &'a Handlers<B>,
) -> Option<&'a ErrorHandler<B>> {
handlers
.get(status)
.map(|h| h.as_ref())
.or_else(|| status.is_client_error().then_some(default_client).flatten())
.or_else(|| status.is_server_error().then_some(default_server).flatten())
}
}
impl<S, B> Transform<S, ServiceRequest> for ErrorHandlers<B>
where
S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
S::Future: 'static,
B: 'static,
{
type Response = ServiceResponse<EitherBody<B>>;
type Error = Error;
type Transform = ErrorHandlersMiddleware<S, B>;
type InitError = ();
type Future = LocalBoxFuture<'static, Result<Self::Transform, Self::InitError>>;
fn new_transform(&self, service: S) -> Self::Future {
let handlers = Rc::clone(&self.handlers);
let default_client = self.default_client.clone();
let default_server = self.default_server.clone();
Box::pin(async move {
Ok(ErrorHandlersMiddleware {
service,
default_client,
default_server,
handlers,
})
})
}
}
#[doc(hidden)]
pub struct ErrorHandlersMiddleware<S, B> {
service: S,
default_client: DefaultHandler<B>,
default_server: DefaultHandler<B>,
handlers: Handlers<B>,
}
impl<S, B> Service<ServiceRequest> for ErrorHandlersMiddleware<S, B>
where
S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error>,
S::Future: 'static,
B: 'static,
{
type Response = ServiceResponse<EitherBody<B>>;
type Error = Error;
type Future = ErrorHandlersFuture<S::Future, B>;
actix_service::forward_ready!(service);
fn call(&self, req: ServiceRequest) -> Self::Future {
let handlers = Rc::clone(&self.handlers);
let default_client = self.default_client.clone();
let default_server = self.default_server.clone();
let fut = self.service.call(req);
ErrorHandlersFuture::ServiceFuture {
fut,
default_client,
default_server,
handlers,
}
}
}
pin_project! {
#[project = ErrorHandlersProj]
pub enum ErrorHandlersFuture<Fut, B>
where
Fut: Future,
{
ServiceFuture {
#[pin]
fut: Fut,
default_client: DefaultHandler<B>,
default_server: DefaultHandler<B>,
handlers: Handlers<B>,
},
ErrorHandlerFuture {
fut: LocalBoxFuture<'static, Result<ServiceResponse<EitherBody<B>>, Error>>,
},
}
}
impl<Fut, B> Future for ErrorHandlersFuture<Fut, B>
where
Fut: Future<Output = Result<ServiceResponse<B>, Error>>,
{
type Output = Result<ServiceResponse<EitherBody<B>>, Error>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
match self.as_mut().project() {
ErrorHandlersProj::ServiceFuture {
fut,
default_client,
default_server,
handlers,
} => {
let res = ready!(fut.poll(cx))?;
let status = res.status();
let handler = ErrorHandlers::get_handler(
&status,
default_client.as_mut().map(|f| Rc::as_ref(f)),
default_server.as_mut().map(|f| Rc::as_ref(f)),
handlers,
);
match handler {
Some(handler) => match handler(res)? {
ErrorHandlerResponse::Response(res) => Poll::Ready(Ok(res)),
ErrorHandlerResponse::Future(fut) => {
self.as_mut()
.set(ErrorHandlersFuture::ErrorHandlerFuture { fut });
self.poll(cx)
}
},
None => Poll::Ready(Ok(res.map_into_left_body())),
}
}
ErrorHandlersProj::ErrorHandlerFuture { fut } => fut.as_mut().poll(cx),
}
}
}
#[cfg(test)]
mod tests {
use actix_service::IntoService;
use actix_utils::future::ok;
use bytes::Bytes;
use futures_util::FutureExt as _;
use super::*;
use crate::{
body,
http::header::{HeaderValue, CONTENT_TYPE},
test::{self, TestRequest},
};
#[actix_rt::test]
async fn add_header_error_handler() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0001"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
let srv = test::status_service(StatusCode::INTERNAL_SERVER_ERROR);
let mw = ErrorHandlers::new()
.handler(StatusCode::INTERNAL_SERVER_ERROR, error_handler)
.new_transform(srv.into_service())
.await
.unwrap();
let resp = test::call_service(&mw, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
}
#[actix_rt::test]
async fn add_header_error_handler_async() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler<B: 'static>(
mut res: ServiceResponse<B>,
) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0001"));
Ok(ErrorHandlerResponse::Future(
ok(res.map_into_left_body()).boxed_local(),
))
}
let srv = test::status_service(StatusCode::INTERNAL_SERVER_ERROR);
let mw = ErrorHandlers::new()
.handler(StatusCode::INTERNAL_SERVER_ERROR, error_handler)
.new_transform(srv.into_service())
.await
.unwrap();
let resp = test::call_service(&mw, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
}
#[actix_rt::test]
async fn changes_body_type() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler<B>(res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
let (req, res) = res.into_parts();
let res = res.set_body(Bytes::from("sorry, that's no bueno"));
let res = ServiceResponse::new(req, res)
.map_into_boxed_body()
.map_into_right_body();
Ok(ErrorHandlerResponse::Response(res))
}
let srv = test::status_service(StatusCode::INTERNAL_SERVER_ERROR);
let mw = ErrorHandlers::new()
.handler(StatusCode::INTERNAL_SERVER_ERROR, error_handler)
.new_transform(srv.into_service())
.await
.unwrap();
let res = test::call_service(&mw, TestRequest::default().to_srv_request()).await;
assert_eq!(test::read_body(res).await, "sorry, that's no bueno");
}
#[actix_rt::test]
async fn error_thrown() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler<B>(_res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
Err(crate::error::ErrorInternalServerError(
"error in error handler",
))
}
let srv = test::status_service(StatusCode::BAD_REQUEST);
let mw = ErrorHandlers::new()
.handler(StatusCode::BAD_REQUEST, error_handler)
.new_transform(srv.into_service())
.await
.unwrap();
let err = mw
.call(TestRequest::default().to_srv_request())
.await
.unwrap_err();
let res = err.error_response();
assert_eq!(res.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
body::to_bytes(res.into_body()).await.unwrap(),
"error in error handler"
);
}
#[actix_rt::test]
async fn default_error_handler() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0001"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
let make_mw = |status| async move {
ErrorHandlers::new()
.default_handler(error_handler)
.new_transform(test::status_service(status).into_service())
.await
.unwrap()
};
let mw_server = make_mw(StatusCode::INTERNAL_SERVER_ERROR).await;
let mw_client = make_mw(StatusCode::BAD_REQUEST).await;
let resp = test::call_service(&mw_client, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
let resp = test::call_service(&mw_server, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
}
#[actix_rt::test]
async fn default_handlers_separate_client_server() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler_client<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0001"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
#[allow(clippy::unnecessary_wraps)]
fn error_handler_server<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0002"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
let make_mw = |status| async move {
ErrorHandlers::new()
.default_handler_server(error_handler_server)
.default_handler_client(error_handler_client)
.new_transform(test::status_service(status).into_service())
.await
.unwrap()
};
let mw_server = make_mw(StatusCode::INTERNAL_SERVER_ERROR).await;
let mw_client = make_mw(StatusCode::BAD_REQUEST).await;
let resp = test::call_service(&mw_client, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
let resp = test::call_service(&mw_server, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0002");
}
#[actix_rt::test]
async fn default_handlers_specialization() {
#[allow(clippy::unnecessary_wraps)]
fn error_handler_client<B>(mut res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0001"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
#[allow(clippy::unnecessary_wraps)]
fn error_handler_specific<B>(
mut res: ServiceResponse<B>,
) -> Result<ErrorHandlerResponse<B>> {
res.response_mut()
.headers_mut()
.insert(CONTENT_TYPE, HeaderValue::from_static("0003"));
Ok(ErrorHandlerResponse::Response(res.map_into_left_body()))
}
let make_mw = |status| async move {
ErrorHandlers::new()
.default_handler_client(error_handler_client)
.handler(StatusCode::UNPROCESSABLE_ENTITY, error_handler_specific)
.new_transform(test::status_service(status).into_service())
.await
.unwrap()
};
let mw_client = make_mw(StatusCode::BAD_REQUEST).await;
let mw_specific = make_mw(StatusCode::UNPROCESSABLE_ENTITY).await;
let resp = test::call_service(&mw_client, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0001");
let resp = test::call_service(&mw_specific, TestRequest::default().to_srv_request()).await;
assert_eq!(resp.headers().get(CONTENT_TYPE).unwrap(), "0003");
}
}