begin

Cargo.toml

@@ -44,6 +44,7 @@ members = [
     "kitsune-cli",
     "kitsune-job-runner",
     "lib/athena",
+    "lib/csurf",
     "lib/masto-id-convert",
     "lib/post-process",
     "lib/speedy-uuid",

lib/csurf/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "csurf"
+authors.workspace = true
+edition.workspace = true
+version.workspace = true
+
+[dependencies]
+http = "0.2.11"
+tower = { version = "0.4.13", default-features = false }
+zeroize = { version = "1.7.0", features = ["derive"] }
+
+[lints]
+workspace = true

lib/csurf/README.md

@@ -0,0 +1,5 @@
+# csurf
+
+Small stateless CSRF crate for tower-based frameworks
+
+Implements the [Signed Double-Submit Cookie](https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#signed-double-submit-cookie-recommended) pattern, as recommended by OWASP.

lib/csurf/src/lib.rs

@@ -0,0 +1,50 @@
+use http::{Request, Response};
+use std::task::{self, Poll};
+use tower::{Layer, Service};
+use zeroize::{Zeroize, ZeroizeOnDrop};
+
+#[derive(Zeroize, ZeroizeOnDrop)]
+pub struct Signer {}
+
+#[derive(Clone, Zeroize, ZeroizeOnDrop)]
+pub struct CsrfLayer {
+    key: Vec<u8>,
+}
+
+impl<S> Layer<S> for CsrfLayer {
+    type Service = CsrfService<S>;
+
+    fn layer(&self, inner: S) -> Self::Service {
+        CsrfService::new(inner, self.key.clone())
+    }
+}
+
+#[derive(Clone, Zeroize, ZeroizeOnDrop)]
+pub struct CsrfService<S> {
+    #[zeroize(skip)]
+    inner: S,
+    key: Vec<u8>,
+}
+
+impl<S> CsrfService<S> {
+    pub fn new(inner: S, key: Vec<u8>) -> Self {
+        Self { inner, key }
+    }
+}
+
+impl<S, ReqBody, ResBody> Service<Request<ReqBody>> for CsrfService<S>
+where
+    S: Service<Request<ReqBody>, Response = Response<ResBody>>,
+{
+    type Error = S::Error;
+    type Future = S::Future;
+    type Response = S::Response;
+
+    fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.inner.poll_ready(cx)
+    }
+
+    fn call(&mut self, req: Request<ReqBody>) -> Self::Future {
+        self.inner.call(req)
+    }
+}