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//! Rejections
//!
//! Part of the power of the [`Filter`](../trait.Filter.html) system is being able to
//! reject a request from a filter chain. This allows for filters to be
//! combined with `or`, so that if one side of the chain finds that a request
//! doesn't fulfill its requirements, the other side can try to process
//! the request.
//!
//! Many of the built-in [`filters`](../filters) will automatically reject
//! the request with an appropriate rejection. However, you can also build
//! new custom [`Filter`](../trait.Filter.html)s and still want other routes to be
//! matchable in the case a predicate doesn't hold.
//!
//! As a request is processed by a Filter chain, the rejections are accumulated into
//! a list contained by the [`Rejection`](struct.Rejection.html) type. Rejections from
//! filters can be handled using [`Filter::recover`](../trait.Filter.html#method.recover).
//! This is a convenient way to map rejections into a [`Reply`](../reply/trait.Reply.html).
//!
//! For a more complete example see the
//! from the repository.
//!
//! # Example
//!
//! ```
//! use warp::{reply, Reply, Filter, reject, Rejection, http::StatusCode};
//!
//! #[derive(Debug)]
//! struct InvalidParameter;
//!
//! impl reject::Reject for InvalidParameter {}
//!
//! // Custom rejection handler that maps rejections into responses.
//! async fn handle_rejection(err: Rejection) -> Result<impl Reply, std::convert::Infallible> {
//! if err.is_not_found() {
//! Ok(reply::with_status("NOT_FOUND", StatusCode::NOT_FOUND))
//! } else if let Some(e) = err.find::<InvalidParameter>() {
//! Ok(reply::with_status("BAD_REQUEST", StatusCode::BAD_REQUEST))
//! } else {
//! eprintln!("unhandled rejection: {:?}", err);
//! Ok(reply::with_status("INTERNAL_SERVER_ERROR", StatusCode::INTERNAL_SERVER_ERROR))
//! }
//! }
//!
//!
//! // Filter on `/:id`, but reject with InvalidParameter if the `id` is `0`.
//! // Recover from this rejection using a custom rejection handler.
//! let route = warp::path::param()
//! .and_then(|id: u32| async move {
//! if id == 0 {
//! Err(warp::reject::custom(InvalidParameter))
//! } else {
//! Ok("id is valid")
//! }
//! })
//! .recover(handle_rejection);
//! ```
use std::any::Any;
use std::convert::Infallible;
use std::error::Error as StdError;
use std::fmt;
use http::{
header::{HeaderValue, CONTENT_TYPE},
StatusCode,
};
use hyper::Body;
pub(crate) use self::sealed::{CombineRejection, IsReject};
/// Rejects a request with `404 Not Found`.
#[inline]
pub fn reject() -> Rejection {
not_found()
}
/// Rejects a request with `404 Not Found`.
#[inline]
pub fn not_found() -> Rejection {
Rejection {
reason: Reason::NotFound,
}
}
// 400 Bad Request
#[inline]
pub(crate) fn invalid_query() -> Rejection {
known(InvalidQuery { _p: () })
}
// 400 Bad Request
#[inline]
pub(crate) fn missing_header(name: &'static str) -> Rejection {
known(MissingHeader { name })
}
// 400 Bad Request
#[inline]
pub(crate) fn invalid_header(name: &'static str) -> Rejection {
known(InvalidHeader { name })
}
// 400 Bad Request
#[inline]
pub(crate) fn missing_cookie(name: &'static str) -> Rejection {
known(MissingCookie { name })
}
// 405 Method Not Allowed
#[inline]
pub(crate) fn method_not_allowed() -> Rejection {
known(MethodNotAllowed { _p: () })
}
// 411 Length Required
#[inline]
pub(crate) fn length_required() -> Rejection {
known(LengthRequired { _p: () })
}
// 413 Payload Too Large
#[inline]
pub(crate) fn payload_too_large() -> Rejection {
known(PayloadTooLarge { _p: () })
}
// 415 Unsupported Media Type
//
// Used by the body filters if the request payload content-type doesn't match
// what can be deserialized.
#[inline]
pub(crate) fn unsupported_media_type() -> Rejection {
known(UnsupportedMediaType { _p: () })
}
/// Rejects a request with a custom cause.
///
/// A [`recover`][] filter should convert this `Rejection` into a `Reply`,
/// or else this will be returned as a `500 Internal Server Error`.
///
/// [`recover`]: ../trait.Filter.html#method.recover
pub fn custom<T: Reject>(err: T) -> Rejection {
Rejection::custom(Box::new(err))
}
/// Protect against re-rejecting a rejection.
///
/// ```compile_fail
/// fn with(r: warp::Rejection) {
/// let _wat = warp::reject::custom(r);
/// }
/// ```
fn __reject_custom_compilefail() {}
/// A marker trait to ensure proper types are used for custom rejections.
///
/// Can be converted into Rejection.
///
/// # Example
///
/// ```
/// use warp::{Filter, reject::Reject};
///
/// #[derive(Debug)]
/// struct RateLimited;
///
/// impl Reject for RateLimited {}
///
/// let route = warp::any().and_then(|| async {
/// Err::<(), _>(warp::reject::custom(RateLimited))
/// });
/// ```
// Require `Sized` for now to prevent passing a `Box<dyn Reject>`, since we
// would be double-boxing it, and the downcasting wouldn't work as expected.
pub trait Reject: fmt::Debug + Sized + Send + Sync + 'static {}
trait Cause: fmt::Debug + Send + Sync + 'static {
fn as_any(&self) -> &dyn Any;
}
impl<T> Cause for T
where
T: fmt::Debug + Send + Sync + 'static,
{
fn as_any(&self) -> &dyn Any {
self
}
}
impl dyn Cause {
fn downcast_ref<T: Any>(&self) -> Option<&T> {
self.as_any().downcast_ref::<T>()
}
}
pub(crate) fn known<T: Into<Known>>(err: T) -> Rejection {
Rejection::known(err.into())
}
/// Rejection of a request by a [`Filter`](crate::Filter).
///
/// See the [`reject`](module@crate::reject) documentation for more.
pub struct Rejection {
reason: Reason,
}
enum Reason {
NotFound,
Other(Box<Rejections>),
}
enum Rejections {
Known(Known),
Custom(Box<dyn Cause>),
Combined(Box<Rejections>, Box<Rejections>),
}
macro_rules! enum_known {
($($(#[$attr:meta])* $var:ident($ty:path),)+) => (
pub(crate) enum Known {
$(
$(#[$attr])*
$var($ty),
)+
}
impl Known {
fn inner_as_any(&self) -> &dyn Any {
match *self {
$(
$(#[$attr])*
Known::$var(ref t) => t,
)+
}
}
}
impl fmt::Debug for Known {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
$(
$(#[$attr])*
Known::$var(ref t) => t.fmt(f),
)+
}
}
}
impl fmt::Display for Known {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
$(
$(#[$attr])*
Known::$var(ref t) => t.fmt(f),
)+
}
}
}
$(
#[doc(hidden)]
$(#[$attr])*
impl From<$ty> for Known {
fn from(ty: $ty) -> Known {
Known::$var(ty)
}
}
)+
);
}
enum_known! {
MethodNotAllowed(MethodNotAllowed),
InvalidHeader(InvalidHeader),
MissingHeader(MissingHeader),
MissingCookie(MissingCookie),
InvalidQuery(InvalidQuery),
LengthRequired(LengthRequired),
PayloadTooLarge(PayloadTooLarge),
UnsupportedMediaType(UnsupportedMediaType),
FileOpenError(crate::fs::FileOpenError),
FilePermissionError(crate::fs::FilePermissionError),
BodyReadError(crate::body::BodyReadError),
BodyDeserializeError(crate::body::BodyDeserializeError),
CorsForbidden(crate::cors::CorsForbidden),
#[cfg(feature = "websocket")]
MissingConnectionUpgrade(crate::ws::MissingConnectionUpgrade),
MissingExtension(crate::ext::MissingExtension),
BodyConsumedMultipleTimes(crate::body::BodyConsumedMultipleTimes),
}
impl Rejection {
fn known(known: Known) -> Self {
Rejection {
reason: Reason::Other(Box::new(Rejections::Known(known))),
}
}
fn custom(other: Box<dyn Cause>) -> Self {
Rejection {
reason: Reason::Other(Box::new(Rejections::Custom(other))),
}
}
/// Searches this `Rejection` for a specific cause.
///
/// A `Rejection` will accumulate causes over a `Filter` chain. This method
/// can search through them and return the first cause of this type.
///
/// # Example
///
/// ```
/// #[derive(Debug)]
/// struct Nope;
///
/// impl warp::reject::Reject for Nope {}
///
/// let reject = warp::reject::custom(Nope);
///
/// if let Some(nope) = reject.find::<Nope>() {
/// println!("found it: {:?}", nope);
/// }
/// ```
pub fn find<T: 'static>(&self) -> Option<&T> {
if let Reason::Other(ref rejections) = self.reason {
return rejections.find();
}
None
}
/// Returns true if this Rejection was made via `warp::reject::not_found`.
///
/// # Example
///
/// ```
/// let rejection = warp::reject();
///
/// assert!(rejection.is_not_found());
/// ```
pub fn is_not_found(&self) -> bool {
matches!(self.reason, Reason::NotFound)
}
}
impl<T: Reject> From<T> for Rejection {
#[inline]
fn from(err: T) -> Rejection {
custom(err)
}
}
impl From<Infallible> for Rejection {
#[inline]
fn from(infallible: Infallible) -> Rejection {
match infallible {}
}
}
impl IsReject for Infallible {
fn status(&self) -> StatusCode {
match *self {}
}
fn into_response(&self) -> crate::reply::Response {
match *self {}
}
}
impl IsReject for Rejection {
fn status(&self) -> StatusCode {
match self.reason {
Reason::NotFound => StatusCode::NOT_FOUND,
Reason::Other(ref other) => other.status(),
}
}
fn into_response(&self) -> crate::reply::Response {
match self.reason {
Reason::NotFound => {
let mut res = http::Response::default();
*res.status_mut() = StatusCode::NOT_FOUND;
res
}
Reason::Other(ref other) => other.into_response(),
}
}
}
impl fmt::Debug for Rejection {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("Rejection").field(&self.reason).finish()
}
}
impl fmt::Debug for Reason {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Reason::NotFound => f.write_str("NotFound"),
Reason::Other(ref other) => match **other {
Rejections::Known(ref e) => fmt::Debug::fmt(e, f),
Rejections::Custom(ref e) => fmt::Debug::fmt(e, f),
Rejections::Combined(ref a, ref b) => {
let mut list = f.debug_list();
a.debug_list(&mut list);
b.debug_list(&mut list);
list.finish()
}
},
}
}
}
// ===== Rejections =====
impl Rejections {
fn status(&self) -> StatusCode {
match *self {
Rejections::Known(ref k) => match *k {
Known::MethodNotAllowed(_) => StatusCode::METHOD_NOT_ALLOWED,
Known::InvalidHeader(_)
| Known::MissingHeader(_)
| Known::MissingCookie(_)
| Known::InvalidQuery(_)
| Known::BodyReadError(_)
| Known::BodyDeserializeError(_) => StatusCode::BAD_REQUEST,
#[cfg(feature = "websocket")]
Known::MissingConnectionUpgrade(_) => StatusCode::BAD_REQUEST,
Known::LengthRequired(_) => StatusCode::LENGTH_REQUIRED,
Known::PayloadTooLarge(_) => StatusCode::PAYLOAD_TOO_LARGE,
Known::UnsupportedMediaType(_) => StatusCode::UNSUPPORTED_MEDIA_TYPE,
Known::FilePermissionError(_) | Known::CorsForbidden(_) => StatusCode::FORBIDDEN,
Known::FileOpenError(_)
| Known::MissingExtension(_)
| Known::BodyConsumedMultipleTimes(_) => StatusCode::INTERNAL_SERVER_ERROR,
},
Rejections::Custom(..) => StatusCode::INTERNAL_SERVER_ERROR,
Rejections::Combined(..) => self.preferred().status(),
}
}
fn into_response(&self) -> crate::reply::Response {
match *self {
Rejections::Known(ref e) => {
let mut res = http::Response::new(Body::from(e.to_string()));
*res.status_mut() = self.status();
res.headers_mut().insert(
CONTENT_TYPE,
HeaderValue::from_static("text/plain; charset=utf-8"),
);
res
}
Rejections::Custom(ref e) => {
tracing::error!(
"unhandled custom rejection, returning 500 response: {:?}",
e
);
let body = format!("Unhandled rejection: {:?}", e);
let mut res = http::Response::new(Body::from(body));
*res.status_mut() = self.status();
res.headers_mut().insert(
CONTENT_TYPE,
HeaderValue::from_static("text/plain; charset=utf-8"),
);
res
}
Rejections::Combined(..) => self.preferred().into_response(),
}
}
fn find<T: 'static>(&self) -> Option<&T> {
match *self {
Rejections::Known(ref e) => e.inner_as_any().downcast_ref(),
Rejections::Custom(ref e) => e.downcast_ref(),
Rejections::Combined(ref a, ref b) => a.find().or_else(|| b.find()),
}
}
fn debug_list(&self, f: &mut fmt::DebugList<'_, '_>) {
match *self {
Rejections::Known(ref e) => {
f.entry(e);
}
Rejections::Custom(ref e) => {
f.entry(e);
}
Rejections::Combined(ref a, ref b) => {
a.debug_list(f);
b.debug_list(f);
}
}
}
fn preferred(&self) -> &Rejections {
match self {
Rejections::Known(_) | Rejections::Custom(_) => self,
Rejections::Combined(a, b) => {
let a = a.preferred();
let b = b.preferred();
// Now both a and b are known or custom, so it is safe
// to get status
// Compare status codes, with this priority:
// - NOT_FOUND is lowest
// - METHOD_NOT_ALLOWED is second
// - if one status code is greater than the other
// - otherwise, prefer A...
match (a.status(), b.status()) {
(_, StatusCode::NOT_FOUND) => a,
(StatusCode::NOT_FOUND, _) => b,
(_, StatusCode::METHOD_NOT_ALLOWED) => a,
(StatusCode::METHOD_NOT_ALLOWED, _) => b,
(sa, sb) if sa < sb => b,
_ => a,
}
}
}
}
}
unit_error! {
/// Invalid query
pub InvalidQuery: "Invalid query string"
}
unit_error! {
/// HTTP method not allowed
pub MethodNotAllowed: "HTTP method not allowed"
}
unit_error! {
/// A content-length header is required
pub LengthRequired: "A content-length header is required"
}
unit_error! {
/// The request payload is too large
pub PayloadTooLarge: "The request payload is too large"
}
unit_error! {
/// The request's content-type is not supported
pub UnsupportedMediaType: "The request's content-type is not supported"
}
/// Missing request header
#[derive(Debug)]
pub struct MissingHeader {
name: &'static str,
}
impl MissingHeader {
/// Retrieve the name of the header that was missing
pub fn name(&self) -> &str {
self.name
}
}
impl fmt::Display for MissingHeader {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Missing request header {:?}", self.name)
}
}
impl StdError for MissingHeader {}
/// Invalid request header
#[derive(Debug)]
pub struct InvalidHeader {
name: &'static str,
}
impl InvalidHeader {
/// Retrieve the name of the header that was invalid
pub fn name(&self) -> &str {
self.name
}
}
impl fmt::Display for InvalidHeader {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Invalid request header {:?}", self.name)
}
}
impl StdError for InvalidHeader {}
/// Missing cookie
#[derive(Debug)]
pub struct MissingCookie {
name: &'static str,
}
impl MissingCookie {
/// Retrieve the name of the cookie that was missing
pub fn name(&self) -> &str {
self.name
}
}
impl fmt::Display for MissingCookie {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Missing request cookie {:?}", self.name)
}
}
impl StdError for MissingCookie {}
mod sealed {
use super::{Reason, Rejection, Rejections};
use http::StatusCode;
use std::convert::Infallible;
use std::fmt;
// This sealed trait exists to allow Filters to return either `Rejection`
// or `!`. There are no other types that make sense, and so it is sealed.
pub trait IsReject: fmt::Debug + Send + Sync {
fn status(&self) -> StatusCode;
fn into_response(&self) -> crate::reply::Response;
}
fn _assert_object_safe() {
fn _assert(_: &dyn IsReject) {}
}
// This weird trait is to allow optimizations of propagating when a
// rejection can *never* happen (currently with the `Never` type,
// eventually to be replaced with `!`).
//
// Using this trait means the `Never` gets propagated to chained filters,
// allowing LLVM to eliminate more code paths. Without it, such as just
// requiring that `Rejection::from(Never)` were used in those filters,
// would mean that links later in the chain may assume a rejection *could*
// happen, and no longer eliminate those branches.
pub trait CombineRejection<E>: Send + Sized {
/// The type that should be returned when only 1 of the two
/// "rejections" occurs.
///
/// # For example:
///
/// `warp::any().and(warp::path("foo"))` has the following steps:
///
/// 1. Since this is `and`, only **one** of the rejections will occur,
/// and as soon as it does, it will be returned.
/// 2. `warp::any()` rejects with `Never`. So, it will never return `Never`.
/// 3. `warp::path()` rejects with `Rejection`. It may return `Rejection`.
///
/// Thus, if the above filter rejects, it will definitely be `Rejection`.
type One: IsReject + From<Self> + From<E> + Into<Rejection>;
/// The type that should be returned when both rejections occur,
/// and need to be combined.
type Combined: IsReject;
fn combine(self, other: E) -> Self::Combined;
}
impl CombineRejection<Rejection> for Rejection {
type One = Rejection;
type Combined = Rejection;
fn combine(self, other: Rejection) -> Self::Combined {
let reason = match (self.reason, other.reason) {
(Reason::Other(left), Reason::Other(right)) => {
Reason::Other(Box::new(Rejections::Combined(left, right)))
}
(Reason::Other(other), Reason::NotFound)
| (Reason::NotFound, Reason::Other(other)) => {
// ignore the NotFound
Reason::Other(other)
}
(Reason::NotFound, Reason::NotFound) => Reason::NotFound,
};
Rejection { reason }
}
}
impl CombineRejection<Infallible> for Rejection {
type One = Rejection;
type Combined = Infallible;
fn combine(self, other: Infallible) -> Self::Combined {
match other {}
}
}
impl CombineRejection<Rejection> for Infallible {
type One = Rejection;
type Combined = Infallible;
fn combine(self, _: Rejection) -> Self::Combined {
match self {}
}
}
impl CombineRejection<Infallible> for Infallible {
type One = Infallible;
type Combined = Infallible;
fn combine(self, _: Infallible) -> Self::Combined {
match self {}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[derive(Debug, PartialEq)]
struct Left;
#[derive(Debug, PartialEq)]
struct Right;
impl Reject for Left {}
impl Reject for Right {}
#[test]
fn rejection_status() {
assert_eq!(not_found().status(), StatusCode::NOT_FOUND);
assert_eq!(
method_not_allowed().status(),
StatusCode::METHOD_NOT_ALLOWED
);
assert_eq!(length_required().status(), StatusCode::LENGTH_REQUIRED);
assert_eq!(payload_too_large().status(), StatusCode::PAYLOAD_TOO_LARGE);
assert_eq!(
unsupported_media_type().status(),
StatusCode::UNSUPPORTED_MEDIA_TYPE
);
assert_eq!(custom(Left).status(), StatusCode::INTERNAL_SERVER_ERROR);
}
#[tokio::test]
async fn combine_rejection_causes_with_some_left_and_none_right() {
let left = custom(Left);
let right = not_found();
let reject = left.combine(right);
let resp = reject.into_response();
assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
response_body_string(resp).await,
"Unhandled rejection: Left"
)
}
#[tokio::test]
async fn combine_rejection_causes_with_none_left_and_some_right() {
let left = not_found();
let right = custom(Right);
let reject = left.combine(right);
let resp = reject.into_response();
assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
response_body_string(resp).await,
"Unhandled rejection: Right"
)
}
#[tokio::test]
async fn unhandled_customs() {
let reject = not_found().combine(custom(Right));
let resp = reject.into_response();
assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
response_body_string(resp).await,
"Unhandled rejection: Right"
);
// There's no real way to determine which is worse, since both are a 500,
// so pick the first one.
let reject = custom(Left).combine(custom(Right));
let resp = reject.into_response();
assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
response_body_string(resp).await,
"Unhandled rejection: Left"
);
// With many rejections, custom still is top priority.
let reject = not_found()
.combine(not_found())
.combine(not_found())
.combine(custom(Right))
.combine(not_found());
let resp = reject.into_response();
assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);
assert_eq!(
response_body_string(resp).await,
"Unhandled rejection: Right"
);
}
async fn response_body_string(resp: crate::reply::Response) -> String {
let (_, body) = resp.into_parts();
let body_bytes = hyper::body::to_bytes(body).await.expect("failed concat");
String::from_utf8_lossy(&body_bytes).to_string()
}
#[test]
fn find_cause() {
let rej = custom(Left);
assert_eq!(rej.find::<Left>(), Some(&Left));
let rej = rej.combine(method_not_allowed());
assert_eq!(rej.find::<Left>(), Some(&Left));
assert!(rej.find::<MethodNotAllowed>().is_some(), "MethodNotAllowed");
}
#[test]
fn size_of_rejection() {
assert_eq!(
::std::mem::size_of::<Rejection>(),
::std::mem::size_of::<usize>(),
);
}
#[derive(Debug)]
struct X(#[allow(unused)] u32);
impl Reject for X {}
fn combine_n<F, R>(n: u32, new_reject: F) -> Rejection
where
F: Fn(u32) -> R,
R: Reject,
{
let mut rej = not_found();
for i in 0..n {
rej = rej.combine(custom(new_reject(i)));
}
rej
}
#[test]
fn test_debug() {
let rej = combine_n(3, X);
let s = format!("{:?}", rej);
assert_eq!(s, "Rejection([X(0), X(1), X(2)])");
}
#[test]
fn convert_big_rejections_into_response() {
let mut rejections = Rejections::Custom(Box::new(std::io::Error::from_raw_os_error(100)));
for _ in 0..50 {
rejections = Rejections::Combined(
Box::new(Rejections::Known(Known::MethodNotAllowed(
MethodNotAllowed { _p: () },
))),
Box::new(rejections),
);
}
let reason = Reason::Other(Box::new(rejections));
let rejection = Rejection { reason };
assert_eq!(
StatusCode::INTERNAL_SERVER_ERROR,
rejection.into_response().status()
);
}
}