[tor-commits] [tor/maint-0.4.1] Ignore regular cells in padding circuits.

[nickm at torproject.org]

commit 74c059596527af67f5df38847e86179852bc7005
Author: George Kadianakis <desnacked at riseup.net>
Date:   Mon Aug 5 13:47:07 2019 +0300

    Ignore regular cells in padding circuits.
    
    Padding circuits were regular cells that got closed before their padding
    machine could finish. This means that they can still receive regular cells from
    their past life, but they have no way or reason to answer them anymore. Hence
    let's ignore them before they even get to the proper subsystems.
---
 changes/bug30942    |  4 ++++
 src/core/or/relay.c | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/changes/bug30942 b/changes/bug30942
new file mode 100644
index 000000000..bd6b2ff58
--- /dev/null
+++ b/changes/bug30942
@@ -0,0 +1,4 @@
+  o Minor bugfixes (circuit padding):
+    - Ignore non-padding cells on padding circuits. This addresses various
+      warning messages from subsystems that were not expecting padding
+      circuits. Fixes bug 30942; bugfix on 0.4.1.1-alpha.
\ No newline at end of file
diff --git a/src/core/or/relay.c b/src/core/or/relay.c
index 9f90a0969..9e691a02b 100644
--- a/src/core/or/relay.c
+++ b/src/core/or/relay.c
@@ -1663,6 +1663,17 @@ connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ,
       if (circpad_handle_padding_negotiated(circ, cell, layer_hint) == 0)
         circuit_read_valid_data(TO_ORIGIN_CIRCUIT(circ), rh.length);
       return 0;
+  }
+
+  /* If this is a padding circuit we don't need to parse any other commands
+   * than the padding ones. Just drop them to the floor. */
+  if (circ->purpose == CIRCUIT_PURPOSE_C_CIRCUIT_PADDING) {
+    log_info(domain, "Ignored cell (%d) that arrived in padding circuit.",
+             rh.command);
+    return 0;
+  }
+
+  switch (rh.command) {
     case RELAY_COMMAND_BEGIN:
     case RELAY_COMMAND_BEGIN_DIR:
       if (layer_hint &&