Merge branch 'tor-gitlab/mr/543'

4 files changed, 43 insertions, 6 deletions

diff --git a/changes/ticket40576 b/changes/ticket40576
new file mode 100644
index 0000000000..c9e3745560
--- /dev/null
+++ b/changes/ticket40576
@@ -0,0 +1,5 @@
+  o Minor bugfixes (onion service congestion control):
+    - Avoid a non fatal assert in case we can't setup congestion control on the
+      rendezvous circuit after opening. Fixes bug 40576; bugfix on
+      0.4.7.4-alpha.
+
diff --git a/src/feature/hs/hs_client.c b/src/feature/hs/hs_client.c
index 1ddc5fcb2e..eb68adfd76 100644
--- a/src/feature/hs/hs_client.c
+++ b/src/feature/hs/hs_client.c
@@ -644,6 +644,16 @@ send_introduce1(origin_circuit_t *intro_circ,
     goto tran_err;
   }
 
+  /* Check if the rendevous circuit was setup WITHOUT congestion control but if
+   * it is enabled and the service supports it. This can happen, see
+   * setup_rendezvous_circ_congestion_control() and so close rendezvous circuit
+   * so another one can be created. */
+  if (TO_CIRCUIT(rend_circ)->ccontrol == NULL && congestion_control_enabled()
+      && hs_desc_supports_congestion_control(desc)) {
+    circuit_mark_for_close(TO_CIRCUIT(rend_circ), END_CIRC_REASON_INTERNAL);
+    goto tran_err;
+  }
+
   /* We need to find which intro point in the descriptor we are connected to
    * on intro_circ. */
   ip = find_desc_intro_point_by_ident(intro_circ->hs_ident, desc);
@@ -780,7 +790,14 @@ client_intro_circ_has_opened(origin_circuit_t *circ)
 }
 
 /** Setup the congestion control parameters on the given rendezvous circuit.
- * This looks at the service descriptor flow control line (if any). */
+ * This looks at the service descriptor flow control line (if any).
+ *
+ * It is possible that we are unable to set congestion control on the circuit
+ * if the descriptor can't be found. In that case, the introduction circuit
+ * can't be opened without it so a fetch will be triggered.
+ *
+ * However, if the descriptor asks for congestion control but the RP circuit
+ * doesn't have it, it will be closed and a new circuit will be opened. */
 static void
 setup_rendezvous_circ_congestion_control(origin_circuit_t *circ)
 {
@@ -791,16 +808,16 @@ setup_rendezvous_circ_congestion_control(origin_circuit_t *circ)
   /* Setup congestion control parameters on the circuit. */
   const hs_descriptor_t *desc =
     hs_cache_lookup_as_client(&circ->hs_ident->identity_pk);
-  if (BUG(desc == NULL)) {
-    /* This should really never happened but in case, scream and stop. */
+  if (desc == NULL) {
+    /* This is possible because between launching the circuit and the circuit
+     * ending in opened state, the descriptor could have been removed from the
+     * cache. In this case, we just can't setup congestion control. */
     return;
   }
 
   /* Check if the service lists support for congestion control in its
    * descriptor. If not, we don't setup congestion control. */
-  if (!desc->encrypted_data.flow_control_pv ||
-      !protocol_list_supports_protocol(desc->encrypted_data.flow_control_pv,
-                                       PRT_FLOWCTRL, PROTOVER_FLOWCTRL_CC)) {
+  if (!hs_desc_supports_congestion_control(desc)) {
     return;
   }
 
diff --git a/src/feature/hs/hs_descriptor.c b/src/feature/hs/hs_descriptor.c
index 523ededf8c..15ad9d8efb 100644
--- a/src/feature/hs/hs_descriptor.c
+++ b/src/feature/hs/hs_descriptor.c
@@ -2987,3 +2987,16 @@ hs_descriptor_clear_intro_points(hs_descriptor_t *desc)
     smartlist_clear(ips);
   }
 }
+
+/** Return true iff we support the given descriptor congestion control
+ * parameters. */
+bool
+hs_desc_supports_congestion_control(const hs_descriptor_t *desc)
+{
+  tor_assert(desc);
+
+  /* Validate that we support the protocol version in the descriptor. */
+  return desc->encrypted_data.flow_control_pv &&
+         protocol_list_supports_protocol(desc->encrypted_data.flow_control_pv,
+                                         PRT_FLOWCTRL, PROTOVER_FLOWCTRL_CC);
+}
diff --git a/src/feature/hs/hs_descriptor.h b/src/feature/hs/hs_descriptor.h
index 8f5ee6a2f1..8f42b2138b 100644
--- a/src/feature/hs/hs_descriptor.h
+++ b/src/feature/hs/hs_descriptor.h
@@ -319,6 +319,8 @@ void hs_desc_superencrypted_data_free_contents(
                                         hs_desc_superencrypted_data_t *desc);
 void hs_desc_encrypted_data_free_contents(hs_desc_encrypted_data_t *desc);
 
+bool hs_desc_supports_congestion_control(const hs_descriptor_t *desc);
+
 #ifdef HS_DESCRIPTOR_PRIVATE
 
 /* Encoding. */