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[tor-commits] [tor/release-0.3.5] statistics: Properly count all rendezvous cells (avoid undercounting).
commit 248cbc2d2207a0bc3374cd18a17cda9d1b8a8ef1
Author: George Kadianakis <desnacked@xxxxxxxxxx>
Date: Mon Sep 7 13:17:41 2020 +0300
statistics: Properly count all rendezvous cells (avoid undercounting).
tl;dr We were not counting cells flying from the client to the service, but we
were counting cells flying from the service to the client.
When a rendezvous cell arrives from the client to the RP, the RP forwards it to
the service.
For this to happen, the cell first passes through command_process_relay_cell()
which normally does the statistics counting. However because the `rend_circ`
circuit was not flagged with `circuit_carries_hs_traffic_stats` in
rend_mid_rendezvous(), the cell is not counted there.
Then the cell goes to circuit_receive_relay_cell() which has a special code
block based on `rend_splice` specifically for rendezvous cells, and the cell
gets directly passed to `rend_circ` via a direct call to
circuit_receive_relay_cell(). The cell never passes through
command_process_relay_cell() ever again and hence is never counted by our
rephist module.
The fix here is to flag the `rend_circ` circuit with
`circuit_carries_hs_traffic_stats` so that the cell is counted as soon as it
hits command_process_relay_cell().
Furthermore we avoid double-counting cells since the special code block of
circuit_receive_relay_cell() makes us count rendezvous cells only as they enter
the RP and not as they exit it.
Fixes #40117.
---
changes/bug40117 | 5 +++++
src/feature/rend/rendmid.c | 6 ++++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/changes/bug40117 b/changes/bug40117
new file mode 100644
index 0000000000..77646edf9c
--- /dev/null
+++ b/changes/bug40117
@@ -0,0 +1,5 @@
+ o Major bugfixes (stats, onion services):
+ - Fix a bug where we were undercounting the Tor network's total onion
+ service traffic, by only counting rendezvous traffic originating from
+ services and ignoring any traffic originating from clients. Fixes bug
+ 40117; bugfix on 0.2.6.2-alpha.
diff --git a/src/feature/rend/rendmid.c b/src/feature/rend/rendmid.c
index 3ba48f8858..af02b34e6b 100644
--- a/src/feature/rend/rendmid.c
+++ b/src/feature/rend/rendmid.c
@@ -333,10 +333,12 @@ rend_mid_rendezvous(or_circuit_t *circ, const uint8_t *request,
goto err;
}
- /* Statistics: Mark this circuit as an RP circuit so that we collect
- stats from it. */
+ /* Statistics: Mark circuits as RP circuits */
if (options->HiddenServiceStatistics) {
+ /* `circ` is the RP <-> service circuit */
circ->circuit_carries_hs_traffic_stats = 1;
+ /* `rend_circ` is the client <-> RP circuit */
+ rend_circ->circuit_carries_hs_traffic_stats = 1;
}
/* Send the RENDEZVOUS2 cell to the client. */
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