Fix Windows WEB carrier empty-cookie compatibility

Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>

src/web/http.rs

@@ -39,7 +39,7 @@ use body::{CollectBodyError, CollectedBody, collect_body};
 use decoy::serve_decoy;
 use request::{
     bearer_token_hash, binary_content_type, bridge_candidate, canonical_request_host,
-    canonical_u64_header, client_ip, match_profile,
+    canonical_u64_header, client_ip, compatible_cookie_header, match_profile,
 };
 
 type BoxError = Box<dyn Error + Send + Sync>;
@@ -231,7 +231,7 @@ async fn handle_api(
     runtime: Arc<WebProcessRuntime>,
     vhost: Arc<WebRuntimeVhost>,
 ) -> HttpResponse {
-    if request.uri().query().is_some() || request.headers().contains_key(header::COOKIE) {
+    if request.uri().query().is_some() || !compatible_cookie_header(&request) {
         return serve_decoy(request, vhost, true, &runtime).await;
     }
     let Some(client_ip) = client_ip(&request, peer, client_ip_source, trusted_proxy_cidrs) else {

src/web/http/request.rs

@@ -141,6 +141,16 @@ pub(super) fn binary_content_type<B>(request: &Request<B>) -> bool {
         && value.is_some_and(|value| value.eq_ignore_ascii_case("application/octet-stream"))
 }
 
+/// Accepts no Cookie or the one empty value emitted by restricted Windows WebView2.
+pub(super) fn compatible_cookie_header<B>(request: &Request<B>) -> bool {
+    let values = request.headers().get_all(header::COOKIE);
+    let mut values = values.iter();
+    match values.next() {
+        None => true,
+        Some(value) => value.as_bytes().is_empty() && values.next().is_none(),
+    }
+}
+
 /// Parses one canonical unsigned decimal carrier sequence header.
 pub(super) fn canonical_u64_header<B>(request: &Request<B>, name: &'static str) -> Option<u64> {
     let values = request.headers().get_all(name);
@@ -267,4 +277,46 @@ mod tests {
             .unwrap();
         assert!(canonical_u64_header(&leading_zero, "x-up-seq").is_none());
     }
+
+    #[test]
+    fn cookie_header_accepts_only_absent_or_one_empty_value() {
+        let absent = Request::new(());
+        assert!(compatible_cookie_header(&absent));
+
+        let empty = Request::builder()
+            .header(header::COOKIE, "")
+            .body(())
+            .unwrap();
+        assert!(compatible_cookie_header(&empty));
+
+        let nonempty = Request::builder()
+            .header(header::COOKIE, "state=unexpected")
+            .body(())
+            .unwrap();
+        assert!(!compatible_cookie_header(&nonempty));
+
+        let whitespace = Request::builder()
+            .header(header::COOKIE, " ")
+            .body(())
+            .unwrap();
+        assert!(!compatible_cookie_header(&whitespace));
+
+        let mut duplicate_empty = Request::new(());
+        duplicate_empty
+            .headers_mut()
+            .append(header::COOKIE, "".parse().unwrap());
+        duplicate_empty
+            .headers_mut()
+            .append(header::COOKIE, "".parse().unwrap());
+        assert!(!compatible_cookie_header(&duplicate_empty));
+
+        let mut duplicate_mixed = Request::new(());
+        duplicate_mixed
+            .headers_mut()
+            .append(header::COOKIE, "".parse().unwrap());
+        duplicate_mixed
+            .headers_mut()
+            .append(header::COOKIE, "state=unexpected".parse().unwrap());
+        assert!(!compatible_cookie_header(&duplicate_mixed));
+    }
 }

src/web/http/tests.rs

@@ -403,3 +403,103 @@ async fn https_lanes_is_advertised_and_requires_canonical_lane_headers() {
     generation.stop_sessions().await;
     generation.stop_background_tasks().await;
 }
+
+#[tokio::test]
+async fn windows_restricted_webview_empty_cookie_preserves_the_carrier_flow() {
+    for (index, carrier) in [WebCarrier::Https, WebCarrier::HttpsLanes]
+        .into_iter()
+        .enumerate()
+    {
+        let capability = [12 + index as u8; 32];
+        let mut config = runtime_config(capability, carrier);
+        config.web.timeouts.long_poll_secs = 0;
+        let generation = test_runtime_generation(1, config);
+        let active_runtime = Arc::new(ArcSwap::from(Arc::clone(&generation)));
+        let runtime = WebProcessRuntime::start(active_runtime);
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let encoded = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(capability);
+        let root = format!(
+            "GET /?bridge={encoded} HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nCookie:\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let root_response = request(&listener, &runtime, root).await;
+        let (root_headers, root_body) = split_response(&root_response);
+        assert!(root_headers.starts_with(b"HTTP/1.1 200"));
+        let root_body = std::str::from_utf8(root_body).unwrap();
+        let bootstrap = root_body
+            .split_once("bootstrap='")
+            .and_then(|(_, suffix)| suffix.split_once('\''))
+            .map(|(token, _)| token)
+            .unwrap();
+
+        let hello = frame::encode(FrameType::Hello, 0, &[1]);
+        let create = |cookie: &str| {
+            let mut request = format!(
+                "POST /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {bootstrap}\r\nContent-Type: application/octet-stream\r\n{cookie}Content-Length: {}\r\nConnection: close\r\n\r\n",
+                hello.len()
+            )
+            .into_bytes();
+            request.extend_from_slice(&hello);
+            request
+        };
+        let nonempty_cookie = request(
+            &listener,
+            &runtime,
+            create("Cookie: state=unexpected\r\n"),
+        )
+        .await;
+        assert!(!nonempty_cookie.starts_with(b"HTTP/1.1 200"));
+        let duplicate_cookie = request(
+            &listener,
+            &runtime,
+            create("Cookie:\r\nCookie: state=unexpected\r\n"),
+        )
+        .await;
+        assert!(!duplicate_cookie.starts_with(b"HTTP/1.1 200"));
+
+        let create_response = request(&listener, &runtime, create("Cookie:\r\n")).await;
+        let (create_headers, create_body) = split_response(&create_response);
+        assert!(create_headers.starts_with(b"HTTP/1.1 200"));
+        assert_eq!(
+            response_header(create_headers, "x-carrier-mode"),
+            carrier.as_str()
+        );
+        assert_eq!(create_body, frame::encode(FrameType::Welcome, 0, &[]));
+        let session = response_header(create_headers, "x-session-token").to_string();
+        let lane = (carrier == WebCarrier::HttpsLanes)
+            .then_some("X-Lane-ID: 0\r\n")
+            .unwrap_or_default();
+
+        let pong = frame::encode(FrameType::Pong, 0, &[]);
+        let mut uplink = format!(
+            "POST /api/v1/up HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nContent-Type: application/octet-stream\r\nCookie:\r\nX-Up-Seq: 1\r\n{lane}Content-Length: {}\r\nConnection: close\r\n\r\n",
+            pong.len()
+        )
+        .into_bytes();
+        uplink.extend_from_slice(&pong);
+        let uplink_response = request(&listener, &runtime, uplink).await;
+        let (uplink_headers, _) = split_response(&uplink_response);
+        assert!(uplink_headers.starts_with(b"HTTP/1.1 204"));
+        assert_eq!(response_header(uplink_headers, "x-up-ack"), "1");
+
+        let downlink = format!(
+            "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nX-Down-Cursor: 0\r\n{lane}Content-Length: 0\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let downlink_response = request(&listener, &runtime, downlink).await;
+        let (downlink_headers, _) = split_response(&downlink_response);
+        assert!(downlink_headers.starts_with(b"HTTP/1.1 204"));
+        assert_eq!(response_header(downlink_headers, "x-down-cursor"), "0");
+
+        let close = format!(
+            "DELETE /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let close_response = request(&listener, &runtime, close).await;
+        assert!(close_response.starts_with(b"HTTP/1.1 204"));
+
+        runtime.shutdown().await;
+        generation.stop_sessions().await;
+        generation.stop_background_tasks().await;
+    }
+}