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use std::{sync::Arc, time::Duration};
use base64::{engine::general_purpose::STANDARD, Engine};
use libcsrf::{
AesGcmCsrfProtection, CsrfCookie as RawCsrfCookie, CsrfProtection, CsrfToken as RawCsrfToken,
UnencryptedCsrfCookie,
};
use crate::{
middleware::{CookieJarManager, CookieJarManagerEndpoint},
web::{
cookie::{Cookie, SameSite},
CsrfToken, CsrfVerifier,
},
Endpoint, Middleware, Request, Result,
};
/// Middleware for Cross-Site Request Forgery (CSRF) protection.
///
/// # Example
///
/// ```
/// use poem::{
/// get, handler,
/// http::{header, Method, StatusCode},
/// middleware::Csrf,
/// post,
/// test::TestClient,
/// web::{cookie::Cookie, CsrfToken, CsrfVerifier},
/// Endpoint, EndpointExt, Error, Request, Result, Route,
/// };
/// use serde::Deserialize;
///
/// #[handler]
/// async fn login_ui(token: &CsrfToken) -> String {
/// token.0.clone()
/// }
///
/// #[handler]
/// async fn login(verifier: &CsrfVerifier, req: &Request) -> Result<String> {
/// let csrf_token = req
/// .header("X-CSRF-Token")
/// .ok_or_else(|| Error::from_status(StatusCode::UNAUTHORIZED))?;
///
/// if !verifier.is_valid(&csrf_token) {
/// return Err(Error::from_status(StatusCode::UNAUTHORIZED));
/// }
///
/// Ok(format!("login success"))
/// }
///
/// # tokio::runtime::Runtime::new().unwrap().block_on(async {
/// let app = Route::new()
/// .at("/", get(login_ui).post(login))
/// .with(Csrf::new());
/// let cli = TestClient::new(app);
///
/// let resp = cli.get("/").send().await;
/// resp.assert_status_is_ok();
///
/// let cookie = resp.0.headers().get(header::SET_COOKIE).unwrap();
/// let cookie = Cookie::parse(cookie.to_str().unwrap()).unwrap();
/// let csrf_token = resp.0.into_body().into_string().await.unwrap();
///
/// let resp = cli
/// .post("/")
/// .header("X-CSRF-Token", csrf_token)
/// .header(
/// header::COOKIE,
/// format!("{}={}", cookie.name(), cookie.value_str()),
/// )
/// .send()
/// .await;
/// resp.assert_status_is_ok();
/// resp.assert_text("login success").await;
/// # });
/// ```
#[cfg_attr(docsrs, doc(cfg(feature = "csrf")))]
pub struct Csrf {
cookie_name: String,
key: [u8; 32],
secure: bool,
http_only: bool,
same_site: Option<SameSite>,
ttl: Duration,
}
impl Default for Csrf {
fn default() -> Self {
Self {
cookie_name: "poem-csrf-token".to_string(),
key: Default::default(),
secure: true,
http_only: true,
same_site: Some(SameSite::Strict),
ttl: Duration::from_secs(24 * 60 * 60),
}
}
}
impl Csrf {
/// Create `Csrf` middleware.
pub fn new() -> Self {
Default::default()
}
/// Sets AES256 key to provide signed, encrypted CSRF tokens and cookies.
#[must_use]
pub fn key(self, key: [u8; 32]) -> Self {
Self { key, ..self }
}
/// Sets the `Secure` to the csrf cookie. Default is `true`.
#[must_use]
pub fn secure(self, value: bool) -> Self {
Self {
secure: value,
..self
}
}
/// Sets the `HttpOnly` to the csrf cookie. Default is `true`.
#[must_use]
pub fn http_only(self, value: bool) -> Self {
Self {
http_only: value,
..self
}
}
/// Sets the `SameSite` to the csrf cookie. Default is
/// [`SameSite::Strict`](libcookie::SameSite::Strict).
#[must_use]
pub fn same_site(self, value: impl Into<Option<SameSite>>) -> Self {
Self {
same_site: value.into(),
..self
}
}
/// Sets the protection ttl. This will be used for both the cookie
/// expiry and the time window over which CSRF tokens are considered
/// valid.
///
/// The default for this value is one day.
#[must_use]
pub fn ttl(self, ttl: Duration) -> Self {
Self { ttl, ..self }
}
}
impl<E: Endpoint> Middleware<E> for Csrf {
type Output = CookieJarManagerEndpoint<CsrfEndpoint<E>>;
fn transform(&self, ep: E) -> Self::Output {
CookieJarManager::new().transform(CsrfEndpoint {
inner: ep,
protect: Arc::new(AesGcmCsrfProtection::from_key(self.key)),
cookie_name: self.cookie_name.clone(),
secure: self.secure,
http_only: self.http_only,
same_site: self.same_site,
ttl: self.ttl,
})
}
}
/// Endpoint for Csrf middleware.
#[cfg_attr(docsrs, doc(cfg(feature = "csrf")))]
pub struct CsrfEndpoint<E> {
inner: E,
protect: Arc<AesGcmCsrfProtection>,
cookie_name: String,
secure: bool,
http_only: bool,
same_site: Option<SameSite>,
ttl: Duration,
}
impl<E> CsrfEndpoint<E> {
fn generate_token(
&self,
existing_cookie: Option<&UnencryptedCsrfCookie>,
) -> (RawCsrfToken, RawCsrfCookie) {
let existing_cookie_bytes = existing_cookie.and_then(|c| {
let c = c.value();
if c.len() < 64 {
None
} else {
let mut buf = [0; 64];
buf.copy_from_slice(c);
Some(buf)
}
});
self.protect
.generate_token_pair(existing_cookie_bytes.as_ref(), self.ttl.as_secs() as i64)
.expect("couldn't generate token/cookie pair")
}
}
impl<E: Endpoint> Endpoint for CsrfEndpoint<E> {
type Output = E::Output;
async fn call(&self, mut req: Request) -> Result<Self::Output> {
let existing_cookie = req
.cookie()
.get(&self.cookie_name)
.and_then(|cookie| STANDARD.decode(cookie.value_str()).ok())
.and_then(|value| self.protect.parse_cookie(&value).ok());
let (token, cookie) = self.generate_token(existing_cookie.as_ref());
let csrf_cookie = {
let mut cookie =
Cookie::new_with_str(&self.cookie_name, STANDARD.encode(cookie.value()));
cookie.set_secure(self.secure);
cookie.set_http_only(self.http_only);
cookie.set_same_site(self.same_site);
cookie.set_max_age(self.ttl);
cookie
};
req.cookie().add(csrf_cookie);
req.extensions_mut()
.insert(CsrfToken(STANDARD.encode(token.value())));
req.extensions_mut()
.insert(CsrfVerifier::new(existing_cookie, self.protect.clone()));
self.inner.call(req).await
}
}
#[cfg(test)]
mod tests {
use http::{header, Method, StatusCode};
use super::*;
use crate::{get, handler, EndpointExt, Error, IntoResponse, Result};
const CSRF_TOKEN_NAME: &str = "X-CSRF-Token";
#[tokio::test]
async fn test_csrf() {
#[handler(internal)]
fn login_ui(token: &CsrfToken) -> impl IntoResponse {
token.0.to_string()
}
#[handler(internal)]
fn login(verifier: &CsrfVerifier, req: &Request) -> Result<impl IntoResponse> {
let token = req
.header(CSRF_TOKEN_NAME)
.ok_or_else(|| Error::from_string("missing token", StatusCode::BAD_REQUEST))?;
match verifier.is_valid(token) {
true => Ok("ok"),
false => Err(Error::from_string("invalid token", StatusCode::BAD_REQUEST)),
}
}
let app = get(login_ui).post(login).with(Csrf::new());
for _ in 0..5 {
let resp = app.call(Request::default()).await.unwrap();
let cookie = resp
.header(header::SET_COOKIE)
.map(|cookie| cookie.to_string())
.unwrap();
let token = resp.into_body().into_string().await.unwrap();
let resp = app
.call(
Request::builder()
.method(Method::POST)
.header(CSRF_TOKEN_NAME, token)
.header(header::COOKIE, cookie)
.finish(),
)
.await
.unwrap()
.into_body()
.into_string()
.await
.unwrap();
assert_eq!(resp, "ok");
}
let resp = app.call(Request::default()).await.unwrap();
let cookie = resp
.header(header::SET_COOKIE)
.map(|cookie| cookie.to_string())
.unwrap();
let token = resp.into_body().into_string().await.unwrap();
let mut token = STANDARD.decode(token).unwrap();
token[0] = token[0].wrapping_add(1);
assert_eq!(
app.call(
Request::builder()
.method(Method::POST)
.header(CSRF_TOKEN_NAME, STANDARD.encode(token))
.header(header::COOKIE, cookie)
.finish(),
)
.await
.unwrap_err()
.to_string(),
"invalid token"
);
}
}