# Struct actix_cors::Cors

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    pub struct Cors { /* private fields */ }

Expand description

Builder for CORS middleware.

To construct a CORS middleware, call `Cors::default()` to create a blank, restrictive builder. Then use any of the builder methods to customize CORS behavior.

The alternative `Cors::permissive()` constructor is available for local development, allowing all origins and headers, etc. The permissive constructor should not be used in production.

## §Behavior

In all cases, behavior for this crate follows the Fetch Standard CORS protocol. See that document for information on exact semantics for configuration options and combinations.

## §Errors

Errors surface in the middleware initialization phase. This means that, if you have logs enabled in Actix Web (using `env_logger` or other crate that exposes logs from the `log` crate), error messages will outline what is wrong with the CORS configuration in the server logs and the server will fail to start up or serve requests.

## §Example

    use actix_cors::Cors;
    use actix_web::http::header;

    let cors = Cors::default()
        .allowed_origin("https://www.rust-lang.org")
        .allowed_methods(vec!["GET", "POST"])
        .allowed_headers(vec![header::AUTHORIZATION, header::ACCEPT])
        .allowed_header(header::CONTENT_TYPE)
        .max_age(3600);

    // `cors` can now be used in `App::wrap`.

## Implementations§

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### impl Cors

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#### pub fn permissive() -> Self

Constructs a very permissive set of defaults for quick development. (Not recommended for production use.)

All origins, methods, request headers and exposed headers allowed. Credentials supported. Max age 1 hour. Does not send wildcard.

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#### pub fn allow_any_origin(self) -> Cors

Resets allowed origin list to a state where any origin is accepted.

See `Cors::allowed_origin` for more info on allowed origins.

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#### pub fn allowed_origin(self, origin: &str) -> Cors

Adds an origin that is allowed to make requests.

This method allows specifying a finite set of origins to verify the value of the `Origin` request header. These are `origin-or-null` types in the Fetch Standard.

By default, no origins are accepted.

When this list is set, the client’s `Origin` request header will be checked in a case-sensitive manner.

When all origins are allowed and `send_wildcard` is set, `*` will be sent in the `Access-Control-Allow-Origin` response header. If `send_wildcard` is not set, the client’s `Origin` request header will be echoed back in the `Access-Control-Allow-Origin` response header.

If the origin of the request doesn’t match any allowed origins and at least one `allowed_origin_fn` function is set, these functions will be used to determinate allowed origins.

##### §Initialization Errors

- If supplied origin is not valid uri
- If supplied origin is a wildcard (`*`). `Cors::send_wildcard` should be used instead.

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#### pub fn allowed_origin_fn<F>(self, f: F) -> Cors
where F: Fn(&HeaderValue, &RequestHead) -> bool + 'static,

Determinates allowed origins by processing requests which didn’t match any origins specified in the `allowed_origin`.

The function will receive two parameters, the Origin header value, and the `RequestHead` of each request, which can be used to determine whether to allow the request or not.

If the function returns `true`, the client’s `Origin` request header will be echoed back into the `Access-Control-Allow-Origin` response header.

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#### pub fn allow_any_method(self) -> Cors

Resets allowed methods list to all methods.

See `Cors::allowed_methods` for more info on allowed methods.

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#### pub fn allowed_methods<U, M>(self, methods: U) -> Cors
where U: IntoIterator<Item = M>, M: TryInto<Method>, <M as TryInto<Method>>::Error: Into<HttpError>,

Sets a list of methods which allowed origins can perform.

These will be sent in the `Access-Control-Allow-Methods` response header.

This defaults to an empty set.

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#### pub fn allow_any_header(self) -> Cors

Resets allowed request header list to a state where any header is accepted.

See `Cors::allowed_headers` for more info on allowed request headers.

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#### pub fn allowed_header<H>(self, header: H) -> Cors
where H: TryInto<HeaderName>, <H as TryInto<HeaderName>>::Error: Into<HttpError>,

Add an allowed request header.

See `Cors::allowed_headers` for more info on allowed request headers.

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#### pub fn allowed_headers<U, H>(self, headers: U) -> Cors
where U: IntoIterator<Item = H>, H: TryInto<HeaderName>, <H as TryInto<HeaderName>>::Error: Into<HttpError>,

Sets a list of request header field names which can be used when this resource is accessed by allowed origins.

If `All` is set, whatever is requested by the client in `Access-Control-Request-Headers` will be echoed back in the `Access-Control-Allow-Headers` header.

This defaults to an empty set.

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#### pub fn expose_any_header(self) -> Cors

Resets exposed response header list to a state where all headers are exposed.

See `Cors::expose_headers` for more info on exposed response headers.

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#### pub fn expose_headers<U, H>(self, headers: U) -> Cors
where U: IntoIterator<Item = H>, H: TryInto<HeaderName>, <H as TryInto<HeaderName>>::Error: Into<HttpError>,

Sets a list of headers which are safe to expose to the API of a CORS API specification.

This corresponds to the `Access-Control-Expose-Headers` response header.

This defaults to an empty set.

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#### pub fn max_age(self, max_age: impl Into<Option<usize>>) -> Cors

Sets a maximum time (in seconds) for which this CORS request may be cached.

This value is set as the `Access-Control-Max-Age` header.

Pass a number (of seconds) or use None to disable sending max age header.

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#### pub fn send_wildcard(self) -> Cors

Configures use of wildcard (`*`) origin in responses when appropriate.

If send wildcard is set and the `allowed_origins` parameter is `All`, a wildcard `Access-Control-Allow-Origin` response header is sent, rather than the request’s `Origin` header.

This option CANNOT be used in conjunction with a credential supported configuration. Doing so will result in an error during server startup.

Defaults to disabled.

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#### pub fn supports_credentials(self) -> Cors

Allows users to make authenticated requests.

If true, injects the `Access-Control-Allow-Credentials` header in responses. This allows cookies and credentials to be submitted across domains.

This option CANNOT be used in conjunction with option cannot be used in conjunction with wildcard origins configured. Doing so will result in an error during server startup.

Defaults to disabled.

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#### pub fn allow_private_network_access(self) -> Cors

Allow private network access.

If true, injects the `Access-Control-Allow-Private-Network: true` header in responses if the request contained the `Access-Control-Request-Private-Network: true` header.

For more information on this behavior, see the draft Private Network Access spec.

Defaults to `false`.

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#### pub fn disable_vary_header(self) -> Cors

Disables `Vary` header support.

When enabled the header `Vary: Origin` will be returned as per the Fetch Standard implementation guidelines.

Setting this header when the `Access-Control-Allow-Origin` is dynamically generated (eg. when there is more than one allowed origin, and an Origin other than ‘*’ is returned) informs CDNs and other caches that the CORS headers are dynamic, and cannot be cached.

By default, `Vary` header support is enabled.

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#### pub fn disable_preflight(self) -> Cors

Disables preflight request handling.

When enabled CORS middleware automatically handles `OPTIONS` requests. This is useful for application level middleware.

By default, preflight support is enabled.

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#### pub fn block_on_origin_mismatch(self, block: bool) -> Cors

Configures whether requests should be pre-emptively blocked on mismatched origin.

If `true`, a 400 Bad Request is returned immediately when a request fails origin validation.

If `false`, the request will be processed as normal but relevant CORS headers will not be appended to the response. In this case, the browser is trusted to validate CORS headers and and block requests based on pre-flight requests. Use this setting to allow cURL and other non-browser HTTP clients to function as normal, no matter what `Origin` the request has.

Defaults to false.

## Trait Implementations§

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### impl Debug for Cors

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl Default for Cors

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#### fn default() -> Cors

A restrictive (security paranoid) set of defaults.

No allowed origins, methods, request headers or exposed headers. Credentials not supported. No max age (will use browser’s default).

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### impl<S, B> Transform<S, ServiceRequest> for Cors
where S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error>, S::Future: 'static, B: MessageBody + 'static,

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#### type Response = ServiceResponse<EitherBody<B>>

Responses produced by the service.
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#### type Error = Error

Errors produced by the service.
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#### type InitError = ()

Errors produced while building a transform service.
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#### type Transform = CorsMiddleware<S>

The `TransformService` value created by this factory
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#### type Future = Ready<Result<<Cors as Transform<S, ServiceRequest>>::Transform, <Cors as Transform<S, ServiceRequest>>::InitError>>

The future response value.
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#### fn new_transform(&self, service: S) -> Self::Future

Creates and returns a new Transform component, asynchronously

## Auto Trait Implementations§

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### impl !RefUnwindSafe for Cors

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### impl !Send for Cors

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### impl !Sync for Cors

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### impl Unpin for Cors

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### impl !UnwindSafe for Cors

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Returns the argument unchanged.

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Instruments this type with the provided [`Span`], returning an `Instrumented` wrapper. Read more
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where U: From<T>,

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Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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Should always be `Self`
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where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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Performs the conversion.
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