1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
use std::{collections::HashSet, rc::Rc};

use actix_utils::future::ok;
use actix_web::{
    body::{EitherBody, MessageBody},
    dev::{forward_ready, Service, ServiceRequest, ServiceResponse},
    http::{
        header::{self, HeaderValue},
        Method,
    },
    Error, HttpResponse, Result,
};
use futures_util::future::{FutureExt as _, LocalBoxFuture};
use log::debug;

use crate::{
    builder::intersperse_header_values,
    inner::{add_vary_header, header_value_try_into_method},
    AllOrSome, CorsError, Inner,
};

/// Service wrapper for Cross-Origin Resource Sharing support.
///
/// This struct contains the settings for CORS requests to be validated and for responses to
/// be generated.
#[doc(hidden)]
#[derive(Debug, Clone)]
pub struct CorsMiddleware<S> {
    pub(crate) service: S,
    pub(crate) inner: Rc<Inner>,
}

impl<S> CorsMiddleware<S> {
    /// Returns true if request is `OPTIONS` and contains an `Access-Control-Request-Method` header.
    fn is_request_preflight(req: &ServiceRequest) -> bool {
        // check request method is OPTIONS
        if req.method() != Method::OPTIONS {
            return false;
        }

        // check follow-up request method is present and valid
        if req
            .headers()
            .get(header::ACCESS_CONTROL_REQUEST_METHOD)
            .and_then(header_value_try_into_method)
            .is_none()
        {
            return false;
        }

        true
    }

    /// Validates preflight request headers against configuration and constructs preflight response.
    ///
    /// Checks:
    /// - `Origin` header is acceptable;
    /// - `Access-Control-Request-Method` header is acceptable;
    /// - `Access-Control-Request-Headers` header is acceptable.
    fn handle_preflight(&self, req: ServiceRequest) -> ServiceResponse {
        let inner = Rc::clone(&self.inner);

        match inner.validate_origin(req.head()) {
            Ok(true) => {}
            Ok(false) => return req.error_response(CorsError::OriginNotAllowed),
            Err(err) => return req.error_response(err),
        };

        if let Err(err) = inner
            .validate_allowed_method(req.head())
            .and_then(|_| inner.validate_allowed_headers(req.head()))
        {
            return req.error_response(err);
        }

        let mut res = HttpResponse::Ok();

        if let Some(origin) = inner.access_control_allow_origin(req.head()) {
            res.insert_header((header::ACCESS_CONTROL_ALLOW_ORIGIN, origin));
        }

        if let Some(ref allowed_methods) = inner.allowed_methods_baked {
            res.insert_header((
                header::ACCESS_CONTROL_ALLOW_METHODS,
                allowed_methods.clone(),
            ));
        }

        if let Some(ref headers) = inner.allowed_headers_baked {
            res.insert_header((header::ACCESS_CONTROL_ALLOW_HEADERS, headers.clone()));
        } else if let Some(headers) = req.headers().get(header::ACCESS_CONTROL_REQUEST_HEADERS) {
            // all headers allowed, return
            res.insert_header((header::ACCESS_CONTROL_ALLOW_HEADERS, headers.clone()));
        }

        #[cfg(feature = "draft-private-network-access")]
        if inner.allow_private_network_access
            && req
                .headers()
                .contains_key("access-control-request-private-network")
        {
            res.insert_header((
                header::HeaderName::from_static("access-control-allow-private-network"),
                HeaderValue::from_static("true"),
            ));
        }

        if inner.supports_credentials {
            res.insert_header((
                header::ACCESS_CONTROL_ALLOW_CREDENTIALS,
                HeaderValue::from_static("true"),
            ));
        }

        if let Some(max_age) = inner.max_age {
            res.insert_header((header::ACCESS_CONTROL_MAX_AGE, max_age.to_string()));
        }

        let mut res = res.finish();

        if inner.vary_header {
            add_vary_header(res.headers_mut());
        }

        req.into_response(res)
    }

    fn augment_response<B>(
        inner: &Inner,
        origin_allowed: bool,
        mut res: ServiceResponse<B>,
    ) -> ServiceResponse<B> {
        if origin_allowed {
            if let Some(origin) = inner.access_control_allow_origin(res.request().head()) {
                res.headers_mut()
                    .insert(header::ACCESS_CONTROL_ALLOW_ORIGIN, origin);
            };
        }

        if let Some(ref expose) = inner.expose_headers_baked {
            log::trace!("exposing selected headers: {:?}", expose);

            res.headers_mut()
                .insert(header::ACCESS_CONTROL_EXPOSE_HEADERS, expose.clone());
        } else if matches!(inner.expose_headers, AllOrSome::All) {
            // intersperse_header_values requires that argument is non-empty
            if !res.headers().is_empty() {
                // extract header names from request
                let expose_all_request_headers = res
                    .headers()
                    .keys()
                    .map(|name| name.as_str())
                    .collect::<HashSet<_>>();

                // create comma separated string of header names
                let expose_headers_value = intersperse_header_values(&expose_all_request_headers);

                log::trace!(
                    "exposing all headers from request: {:?}",
                    expose_headers_value
                );

                // add header names to expose response header
                res.headers_mut()
                    .insert(header::ACCESS_CONTROL_EXPOSE_HEADERS, expose_headers_value);
            }
        }

        if inner.supports_credentials {
            res.headers_mut().insert(
                header::ACCESS_CONTROL_ALLOW_CREDENTIALS,
                HeaderValue::from_static("true"),
            );
        }

        #[cfg(feature = "draft-private-network-access")]
        if inner.allow_private_network_access
            && res
                .request()
                .headers()
                .contains_key("access-control-request-private-network")
        {
            res.headers_mut().insert(
                header::HeaderName::from_static("access-control-allow-private-network"),
                HeaderValue::from_static("true"),
            );
        }

        if inner.vary_header {
            add_vary_header(res.headers_mut());
        }

        res
    }
}

impl<S, B> Service<ServiceRequest> for CorsMiddleware<S>
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error>,
    S::Future: 'static,

    B: MessageBody + 'static,
{
    type Response = ServiceResponse<EitherBody<B>>;
    type Error = Error;
    type Future = LocalBoxFuture<'static, Result<ServiceResponse<EitherBody<B>>, Error>>;

    forward_ready!(service);

    fn call(&self, req: ServiceRequest) -> Self::Future {
        let origin = req.headers().get(header::ORIGIN);

        // handle preflight requests
        if self.inner.preflight && Self::is_request_preflight(&req) {
            let res = self.handle_preflight(req);
            return ok(res.map_into_right_body()).boxed_local();
        }

        // only check actual requests with a origin header
        let origin_allowed = match (origin, self.inner.validate_origin(req.head())) {
            (None, _) => false,
            (_, Ok(origin_allowed)) => origin_allowed,
            (_, Err(err)) => {
                debug!("origin validation failed; inner service is not called");
                let mut res = req.error_response(err);

                if self.inner.vary_header {
                    add_vary_header(res.headers_mut());
                }

                return ok(res.map_into_right_body()).boxed_local();
            }
        };

        let inner = Rc::clone(&self.inner);
        let fut = self.service.call(req);

        Box::pin(async move {
            let res = fut.await;
            Ok(Self::augment_response(&inner, origin_allowed, res?).map_into_left_body())
        })
    }
}

#[cfg(test)]
mod tests {
    use actix_web::{
        dev::Transform,
        middleware::Compat,
        test::{self, TestRequest},
        App,
    };

    use super::*;
    use crate::Cors;

    #[test]
    fn compat_compat() {
        let _ = App::new().wrap(Compat::new(Cors::default()));
    }

    #[actix_web::test]
    async fn test_options_no_origin() {
        // Tests case where allowed_origins is All but there are validate functions to run incase.
        // In this case, origins are only allowed when the DNT header is sent.

        let cors = Cors::default()
            .allow_any_origin()
            .allowed_origin_fn(|origin, req_head| {
                assert_eq!(&origin, req_head.headers.get(header::ORIGIN).unwrap());
                req_head.headers().contains_key(header::DNT)
            })
            .new_transform(test::ok_service())
            .await
            .unwrap();

        let req = TestRequest::get()
            .insert_header((header::ORIGIN, "http://example.com"))
            .to_srv_request();
        let res = cors.call(req).await.unwrap();
        assert_eq!(
            None,
            res.headers()
                .get(header::ACCESS_CONTROL_ALLOW_ORIGIN)
                .map(HeaderValue::as_bytes)
        );

        let req = TestRequest::get()
            .insert_header((header::ORIGIN, "http://example.com"))
            .insert_header((header::DNT, "1"))
            .to_srv_request();
        let res = cors.call(req).await.unwrap();
        assert_eq!(
            Some(&b"http://example.com"[..]),
            res.headers()
                .get(header::ACCESS_CONTROL_ALLOW_ORIGIN)
                .map(HeaderValue::as_bytes)
        );
    }
}