backend: harden auth token validation

backend/src/auth/jwt.rs

@@ -1,6 +1,7 @@
 use chrono::{Duration, Utc};
-use jsonwebtoken::{decode, encode, DecodingKey, EncodingKey, Header, Validation};
+use jsonwebtoken::{decode, encode, Algorithm, DecodingKey, EncodingKey, Header, Validation};
 use serde::{Deserialize, Serialize};
+use std::collections::HashSet;
 use uuid::Uuid;
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -34,10 +35,14 @@ pub fn create_token(
 }
 
 pub fn verify_token(token: &str, secret: &str) -> Result<Claims, jsonwebtoken::errors::Error> {
+    let mut validation = Validation::new(Algorithm::HS256);
+    validation.leeway = 30;
+    validation.required_spec_claims = HashSet::from(["exp".to_string(), "sub".to_string()]);
+
     let token_data = decode::<Claims>(
         token,
         &DecodingKey::from_secret(secret.as_bytes()),
-        &Validation::default(),
+        &validation,
     )?;
     Ok(token_data.claims)
 }

backend/src/auth/middleware.rs

@@ -1,5 +1,6 @@
 use axum::{
     extract::FromRequestParts,
+    http::header,
     http::{request::Parts, StatusCode},
 };
 use std::sync::Arc;
@@ -8,6 +9,7 @@ use uuid::Uuid;
 use super::jwt::{verify_token, Claims};
 use crate::config::Config;
 
+#[derive(Debug)]
 pub struct AuthUser {
     pub user_id: Uuid,
     pub username: String,
@@ -22,23 +24,39 @@ where
     async fn from_request_parts(parts: &mut Parts, _state: &S) -> Result<Self, Self::Rejection> {
         let auth_header = parts
             .headers
-            .get("Authorization")
+            .get(header::AUTHORIZATION)
             .and_then(|value| value.to_str().ok())
             .ok_or((StatusCode::UNAUTHORIZED, "Missing authorization header"))?;
 
-        let token = auth_header.strip_prefix("Bearer ").ok_or((
+        let mut pieces = auth_header.split_whitespace();
+        let scheme = pieces.next().ok_or((
             StatusCode::UNAUTHORIZED,
             "Invalid authorization header format",
         ))?;
+        let token = pieces.next().ok_or((
+            StatusCode::UNAUTHORIZED,
+            "Invalid authorization header format",
+        ))?;
+        if pieces.next().is_some() || !scheme.eq_ignore_ascii_case("bearer") {
+            return Err((
+                StatusCode::UNAUTHORIZED,
+                "Invalid authorization header format",
+            ));
+        }
 
-        let secret = parts
+        let config = parts
             .extensions
             .get::<Arc<Config>>()
-            .map(|c| c.jwt_secret.clone())
-            .or_else(|| std::env::var("JWT_SECRET").ok())
-            .unwrap_or_else(|| "dev-secret-change-in-production".to_string());
+            .ok_or((StatusCode::INTERNAL_SERVER_ERROR, "Auth config missing"))?;
 
-        let claims: Claims = verify_token(token, &secret)
+        if config.jwt_secret.trim().is_empty() {
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "JWT secret not configured",
+            ));
+        }
+
+        let claims: Claims = verify_token(token, &config.jwt_secret)
             .map_err(|_| (StatusCode::UNAUTHORIZED, "Invalid token"))?;
 
         Ok(AuthUser {
@@ -47,3 +65,83 @@ where
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::AuthUser;
+    use crate::auth::create_token;
+    use crate::config::Config;
+    use axum::body::Body;
+    use axum::extract::FromRequestParts;
+    use axum::http::Request;
+    use std::sync::Arc;
+    use uuid::Uuid;
+
+    fn parts_with_auth(
+        auth: Option<&str>,
+        config: Option<Arc<Config>>,
+    ) -> axum::http::request::Parts {
+        let mut req = Request::builder().uri("/").body(Body::empty()).unwrap();
+        if let Some(auth) = auth {
+            req.headers_mut()
+                .insert(axum::http::header::AUTHORIZATION, auth.parse().unwrap());
+        }
+        if let Some(config) = config {
+            req.extensions_mut().insert(config);
+        }
+        let (parts, _) = req.into_parts();
+        parts
+    }
+
+    #[tokio::test]
+    async fn rejects_missing_auth_header() {
+        let config = Arc::new(Config {
+            jwt_secret: "secret".to_string(),
+            ..Config::default()
+        });
+        let mut parts = parts_with_auth(None, Some(config));
+        let err = AuthUser::from_request_parts(&mut parts, &())
+            .await
+            .unwrap_err();
+        assert_eq!(err.0, axum::http::StatusCode::UNAUTHORIZED);
+    }
+
+    #[tokio::test]
+    async fn accepts_bearer_case_insensitive_and_whitespace() {
+        let config = Arc::new(Config {
+            jwt_secret: "secret".to_string(),
+            ..Config::default()
+        });
+        let token = create_token(Uuid::new_v4(), "alice", &config.jwt_secret).unwrap();
+        let auth = format!("  bEaReR   {token}  ");
+        let mut parts = parts_with_auth(Some(&auth), Some(config));
+        let user = AuthUser::from_request_parts(&mut parts, &()).await.unwrap();
+        assert_eq!(user.username, "alice");
+    }
+
+    #[tokio::test]
+    async fn rejects_non_bearer_scheme() {
+        let config = Arc::new(Config {
+            jwt_secret: "secret".to_string(),
+            ..Config::default()
+        });
+        let token = create_token(Uuid::new_v4(), "alice", &config.jwt_secret).unwrap();
+        let auth = format!("Token {token}");
+        let mut parts = parts_with_auth(Some(&auth), Some(config));
+        let err = AuthUser::from_request_parts(&mut parts, &())
+            .await
+            .unwrap_err();
+        assert_eq!(err.0, axum::http::StatusCode::UNAUTHORIZED);
+    }
+
+    #[tokio::test]
+    async fn errors_when_config_missing() {
+        let token = create_token(Uuid::new_v4(), "alice", "secret").unwrap();
+        let auth = format!("Bearer {token}");
+        let mut parts = parts_with_auth(Some(&auth), None);
+        let err = AuthUser::from_request_parts(&mut parts, &())
+            .await
+            .unwrap_err();
+        assert_eq!(err.0, axum::http::StatusCode::INTERNAL_SERVER_ERROR);
+    }
+}

backend/src/rate_limit.rs

@@ -123,7 +123,15 @@ fn parse_ip_from_connect_info<B>(request: &Request<B>) -> Option<IpAddr> {
 
 fn parse_user_from_auth(headers: &HeaderMap, secret: &str) -> Option<Uuid> {
     let auth = headers.get(header::AUTHORIZATION)?.to_str().ok()?;
-    let token = auth.strip_prefix("Bearer ")?;
+    let mut pieces = auth.split_whitespace();
+    let scheme = pieces.next()?;
+    let token = pieces.next()?;
+    if pieces.next().is_some() {
+        return None;
+    }
+    if !scheme.eq_ignore_ascii_case("bearer") {
+        return None;
+    }
     verify_token(token, secret).ok().map(|c| c.sub)
 }