From 907d8cf255a1fc04772894c771670a63f3e25836 Mon Sep 17 00:00:00 2001
From: Gabriela Moldovan <gabi@torproject.org>
Date: Mon, 31 Jul 2023 01:05:58 +0100
Subject: [PATCH] tor-proto: Add TODO regarding allow_stream_requests corner
 case.

---
 crates/tor-proto/src/circuit.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/crates/tor-proto/src/circuit.rs b/crates/tor-proto/src/circuit.rs
index c22970ad4..6946277c6 100644
--- a/crates/tor-proto/src/circuit.rs
+++ b/crates/tor-proto/src/circuit.rs
@@ -436,6 +436,9 @@ impl ClientCirc {
     ///
     /// Only onion services (and eventually) exit relays should call this
     /// method.
+    //
+    // TODO HSS: this function should return an error if allow_stream_requests()
+    // was already called on this circuit.
     #[cfg(feature = "hs-service")]
     pub fn allow_stream_requests(
         self: &Arc<ClientCirc>,
@@ -1837,6 +1840,27 @@ mod test {
         assert_eq!(p.initial_send_window(), 500);
     }
 
+    #[test]
+    // TODO HSS: allow_stream_requests() should return an error if
+    // the circuit already has an IncomingStream.
+    #[ignore]
+    #[cfg(feature = "hs-service")]
+    fn allow_stream_requests_twice() {
+        tor_rtcompat::test_with_all_runtimes!(|rt| async move {
+            let (chan, _rx, _sink) = working_fake_channel(&rt);
+            let (circ, _send) = newcirc(&rt, chan).await;
+
+            let _incoming = circ
+                .allow_stream_requests(&[tor_cell::relaycell::RelayCmd::BEGIN])
+                .unwrap();
+
+            let incoming = circ.allow_stream_requests(&[tor_cell::relaycell::RelayCmd::BEGIN]);
+
+            // There can only be one IncomingStream at a time on any given circuit.
+            assert!(incoming.is_err());
+        });
+    }
+
     #[test]
     #[cfg(feature = "hs-service")]
     fn allow_stream_requests() {