kvarn/cors.rs
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413
//! [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing) implementation for Kvarn.
//!
//! See [`Cors`] for usage details.
use crate::prelude::*;
use extensions::RuleSet;
/// A [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing) ruleset for Kvarn.
///
/// Use [`Extensions::with_cors`] to allow selected CORS requests.
///
/// By default, Kvarn uses a empty [`RuleSet`]; all CORS requests are rejected.
///
/// # Examples
///
/// ```
/// # use kvarn::prelude::*;
/// // Allow `https://icelk.dev` and `https://kvarn.org` to access all images.
/// // Also allow all requests from `http://example.org` access to the api.
/// let cors =
/// Cors::empty()
/// .add(
/// "/images/*",
/// CorsAllowList::new(Duration::from_secs(60*60*24*365))
/// .add_origin("https://icelk.dev")
/// .add_origin("https://kvarn.org")
/// )
/// .add(
/// "/api/*",
/// CorsAllowList::default()
/// .add_origin("http://example.org")
/// .add_method(Method::PUT)
/// .add_method(Method::POST)
/// );
/// ```
pub type Cors = RuleSet<AllowList>;
impl Cors {
/// Check if the (cross-origin) request's `origin` [`Uri`] is allowed by the CORS rules.
///
/// See [`CorsAllowList::check`] for info about the return types.
pub fn check_origin(
&self,
origin: &Uri,
uri_path: &str,
) -> Option<(MethodAllowList, &[HeaderName], Duration)> {
self.get(uri_path).and_then(|cal| cal.check(origin))
}
/// Check if the [`Request::headers`] and [`Request::uri`] is allowed with this ruleset.
///
/// > This will not check for errors in `access-control-request-headers`.
///
/// Use this over [`Self::check_origin`] because this checks for `same_origin` requests.
///
/// See [`CorsAllowList::check`] for info about the return types.
pub fn check_cors_request<T>(
&self,
request: &Request<T>,
) -> Option<(MethodAllowList, &[HeaderName], Duration)> {
let same_origin_allowed_headers = (
MethodAllowList::All,
&[][..],
Duration::from_secs(60 * 60 * 24 * 7),
);
match request.headers().get("origin") {
None => Some(same_origin_allowed_headers),
Some(origin)
if origin.to_str().map_or(false, |origin| {
Cors::is_part_of_origin(origin, request.uri())
}) =>
{
Some(same_origin_allowed_headers)
}
Some(origin) => match Uri::try_from(origin.as_bytes()) {
Ok(origin) => match self.check_origin(&origin, request.uri().path()) {
Some(allowed) if allowed.0.allowed(request.method()) => Some(allowed),
_ => None,
},
Err(_) => None,
},
}
}
/// Checks if `uri` is the same origin as `origin`.
fn is_part_of_origin(origin: &str, uri: &Uri) -> bool {
let uri_parts = origin.split_once("://");
let (origin_scheme, origin_authority) = match uri_parts {
Some((s, o)) => (s, o),
None => return origin == "localhost" || origin == "null",
};
if Some(origin_scheme) != uri.scheme_str() {
return false;
}
uri.authority().map(uri::Authority::as_str) == Some(origin_authority)
}
}
/// A CORS allow list which allowes hosts, methods, and headers from a associated path.
/// This is a builder-like struct.
/// Use the `add_*` methods to add allowed origins, methods, and headers.
/// Multiple allow lists can be added to a [`Cors`] instance.
/// See the example at [`Cors`].
///
/// Use [`RuleSet::add`] to add a rule.
#[must_use]
#[derive(Debug)]
pub struct AllowList {
allowed: Vec<Uri>,
allow_all_origins: bool,
methods: Option<Vec<Method>>,
headers: Vec<HeaderName>,
cache_for: Duration,
}
impl AllowList {
/// Creates a empty CORS allow list with the client cache duration of `cache_for`.
pub fn new(cache_for: Duration) -> Self {
Self {
allowed: Vec::new(),
allow_all_origins: false,
methods: Some(vec![Method::GET, Method::HEAD, Method::OPTIONS]),
headers: Vec::new(),
cache_for,
}
}
/// Allows CORS request from `allowed_origin`.
/// Note that the scheme (`https` / `http`) is sensitive.
/// Use [`Self::add_origin_uri`] for a [`Uri`] input.
///
/// # Panics
///
/// Panics if `allowed_origin` is not a valid [`Uri`]
/// or if it doesn't contain a host AND a scheme.
pub fn add_origin(self, allowed_origin: impl AsRef<str>) -> Self {
self.add_origin_uri(Uri::try_from(allowed_origin.as_ref()).unwrap())
}
/// Allows CORS request from `allowed_origin`.
/// Note that the scheme (`https` / `http`) is sensitive.
///
/// # Panics
///
/// Panics if `allowed_origin` doesn't contain a host AND a scheme.
pub fn add_origin_uri(mut self, allowed_origin: Uri) -> Self {
assert!(allowed_origin.host().is_some());
assert!(allowed_origin.scheme().is_some());
self.allowed.push(allowed_origin);
self
}
/// Enables the flag to allow all origins to use the set methods and headers in CORS requests.
pub fn allow_all_origins(mut self) -> Self {
self.allow_all_origins = true;
self
}
/// Allows the listed origin(s) (added via [`Self::add_origin`])
/// to request using `allowed_method`.
pub fn add_method(mut self, allowed_method: Method) -> Self {
let methods = self.methods.get_or_insert_with(Vec::new);
if !methods.contains(&allowed_method) {
methods.push(allowed_method);
}
self
}
/// Allows all methods.
pub fn allow_all_methods(mut self) -> Self {
self.methods = None;
self
}
/// Allows the listed origin(s) (added via [`Self::add_origin`])
/// to send the `allowed_header` in the request.
pub fn add_header(mut self, allowed_header: HeaderName) -> Self {
if !self.headers.contains(&allowed_header) {
self.headers.push(allowed_header);
}
self
}
fn get_methods(&self) -> MethodAllowList {
self.methods
.as_deref()
.map_or(MethodAllowList::All, MethodAllowList::Selected)
}
/// Checks if the `origin` is allowed according to the allow list.
///
/// Returns [`Some`] if `origin` is allowed, with the [`Method`]s and [`HeaderName`]s
/// allowed, with a cache max-age of [`Duration`].
/// Returns [`None`] if `origin` isn't allowed.
pub fn check(&self, origin: &Uri) -> Option<(MethodAllowList, &[HeaderName], Duration)> {
if self.allow_all_origins {
return Some((self.get_methods(), &self.headers, self.cache_for));
}
for allowed in &self.allowed {
let scheme = allowed.scheme().map_or("https", uri::Scheme::as_str);
// This is OK; we assert it has a host when we add it
if Some(allowed.host().unwrap()) == origin.host()
&& allowed.port_u16() == origin.port_u16()
&& Some(scheme) == origin.scheme().map(uri::Scheme::as_str)
{
return Some((self.get_methods(), &self.headers, self.cache_for));
}
}
None
}
}
/// The default `cache_for` is 1 hour.
impl Default for AllowList {
fn default() -> Self {
Self::new(Duration::from_secs(60 * 60))
}
}
/// The allowed methods.
#[derive(Debug)]
#[must_use]
pub enum MethodAllowList<'a> {
/// All methods are allowed.
All,
/// Only the methods in the slice are allowed.
Selected(&'a [Method]),
}
impl MethodAllowList<'_> {
#[must_use]
fn allowed(&self, method: &Method) -> bool {
match self {
Self::All => true,
Self::Selected(list) => list.contains(method),
}
}
fn to_bytes(&self) -> Bytes {
match self {
Self::All => Bytes::from_static(b"*"),
Self::Selected(list) => list
.iter()
.enumerate()
.fold(BytesMut::with_capacity(24), |mut acc, (pos, method)| {
acc.extend_from_slice(method.as_str().as_bytes());
if pos + 1 != list.len() {
acc.extend_from_slice(b", ");
}
acc
})
.freeze(),
}
}
}
fn options_prepare(options_cors_settings: Arc<Cors>) -> Prepare {
prepare!(request, _, _, _, move |options_cors_settings: Arc<Cors>| {
let allowed = options_cors_settings.check_cors_request(request);
if allowed.is_none() {
return {
let response = Response::builder()
.status(StatusCode::FORBIDDEN)
.body(Bytes::from_static(b"CORS request denied"))
.expect("we know this is a good request.");
FatResponse::new(response, comprash::ServerCachePreference::Full)
};
}
let mut builder = Response::builder().status(StatusCode::NO_CONTENT);
if let Some((methods, headers, cache_for)) = allowed {
let methods = methods.to_bytes();
let headers = headers
.iter()
.enumerate()
.fold(BytesMut::with_capacity(24), |mut acc, (pos, header)| {
acc.extend_from_slice(header.as_str().as_bytes());
if pos + 1 != headers.len() {
acc.extend_from_slice(b", ");
}
acc
})
.freeze();
builder = builder
.header(
"access-control-allow-methods",
// We know all the characters from [`Method::as_str`] are valid.
HeaderValue::from_maybe_shared(methods).unwrap(),
)
.header(
"access-control-allow-headers",
// We know all the characters from [`HeaderName::as_str()`] are valid.
// See https://docs.rs/http/0.2.4/http/header/struct.HeaderValue.html#impl-From%3CHeaderName%3E
HeaderValue::from_maybe_shared(headers).unwrap(),
)
.header(
"access-control-max-age",
// We know a number is valid
HeaderValue::try_from(
// if > second integer, add 1 second (ceil the duration).
// i64::from(bool) returns 1 if true.
(cache_for.as_secs() + u64::from(cache_for.subsec_nanos() > 0)).to_string(),
)
.unwrap(),
);
}
let response = builder.body(Bytes::new()).unwrap_or_else(|_| {
Response::builder()
.status(StatusCode::INTERNAL_SERVER_ERROR)
.body(utils::hardcoded_error_body(
StatusCode::INTERNAL_SERVER_ERROR,
None,
))
.expect("this is a good response.")
});
FatResponse::new(response, comprash::ServerCachePreference::None)
})
}
impl Extensions {
/// Adds extensions to disallow all CORS requests.
/// This is added when calling [`Extensions::new`].
pub fn with_disallow_cors(&mut self) -> &mut Self {
self.add_prime(
prime!(request, _, _, {
let missmatch = request
.headers()
.get("origin")
.and_then(|origin| origin.to_str().ok())
.map_or(false, |origin| {
!Cors::is_part_of_origin(origin, request.uri())
});
if missmatch {
Some(Uri::from_static("/./cors_fail"))
} else {
None
}
}),
Id::new(16_777_216, "Reroute all CORS requests to /./cors_fail"),
);
self.add_prepare_single(
"/./cors_fail",
prepare!(_, _, _, _, {
let response = Response::builder()
.status(StatusCode::FORBIDDEN)
.body(Bytes::from_static(b"CORS request denied"))
.expect("we know this is a good request.");
FatResponse::new(response, comprash::ServerCachePreference::Full)
}),
);
self.add_prepare_single("/./cors_options", options_prepare(Cors::empty().arc()));
self.add_prime(
prime!(request, _, _, {
if request.method() == Method::OPTIONS
&& request.headers().get("origin").is_some()
&& request
.headers()
.get("access-control-request-method")
.is_some()
{
Some(Uri::from_static("/./cors_options"))
} else {
None
}
}),
Id::new(16_777_215, "Provides CORS preflight request support"),
);
self
}
/// Overrides the default handling (deny all) of CORS requests to be `cors_settings`.
///
/// See [`Cors`] for an example and more info.
pub fn with_cors(&mut self, cors_settings: Arc<Cors>) -> &mut Self {
self.with_disallow_cors();
let options_cors_settings = Arc::clone(&cors_settings);
self.add_prepare_single("/./cors_options", options_prepare(options_cors_settings));
let package_cors_settings = Arc::clone(&cors_settings);
// This priority have to be higher than the one in the [`Self::add_disallow_cors`]'s prime
// extension.
self.add_prime(
prime!(request, _, _, move |cors_settings: Arc<Cors>| {
let allow = cors_settings.check_cors_request(request);
if allow.is_some() {
None
} else {
Some(Uri::from_static("/./cors_fail"))
}
}),
Id::new(
16_777_216,
"Reroute not allowed CORS request to /./cors_fail",
),
);
// Low priority so it runs last.
self.add_package(
package!(
response,
request,
_,
_,
move |package_cors_settings: Arc<Cors>| {
if let Some(origin) = request.headers().get("origin") {
let allowed = package_cors_settings.check_cors_request(request).is_some();
if allowed {
response
.headers_mut()
.insert("access-control-allow-origin", origin.clone());
}
}
}
),
Id::new(
-1024,
"Adds access-control-allow-origin depending on if CORS request is allowed",
),
);
self
}
}