From 3cbc513ae767aa872f690ab23f94535aa121975d Mon Sep 17 00:00:00 2001
From: George Kadianakis <desnacked@riseup.net>
Date: Wed, 21 Oct 2020 13:50:32 +0300
Subject: [PATCH] Implement support for "v3 rend traffic" stat.

---
 src/core/or/command.c       | 27 +++++++++++++++++++++++++--
 src/core/or/or_circuit_st.h |  6 ++++++
 src/feature/stats/rephist.c | 14 ++++++++++++++
 src/feature/stats/rephist.h |  2 +-
 4 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/core/or/command.c b/src/core/or/command.c
index 9226309ff7..35dadb9fc8 100644
--- a/src/core/or/command.c
+++ b/src/core/or/command.c
@@ -331,6 +331,13 @@ command_process_create_cell(cell_t *cell, channel_t *chan)
     return;
   }
 
+  /* Mark whether this circuit used TAP in case we need to use this
+   * information for onion service statistics later on. */
+  if (create_cell->handshake_type == ONION_HANDSHAKE_TYPE_FAST ||
+      create_cell->handshake_type == ONION_HANDSHAKE_TYPE_TAP) {
+    circ->used_legacy_circuit_handshake = true;
+  }
+
   if (!channel_is_client(chan)) {
     /* remember create types we've seen, but don't remember them from
      * clients, to be extra conservative about client statistics. */
@@ -587,11 +594,27 @@ command_process_relay_cell(cell_t *cell, channel_t *chan)
   }
 
   /* If this is a cell in an RP circuit, count it as part of the
-     hidden service stats */
+     onion service stats */
   if (options->HiddenServiceStatistics &&
       !CIRCUIT_IS_ORIGIN(circ) &&
       TO_OR_CIRCUIT(circ)->circuit_carries_hs_traffic_stats) {
-    rep_hist_seen_new_rp_cell();
+    /** We need to figure out of this is a v2 or v3 RP circuit to count it
+     *  appropriately. v2 services always use the TAP legacy handshake to
+     *  connect to the RP; we use this feature to distinguish between v2/v3. */
+    bool is_v2 = false;
+    if (TO_OR_CIRCUIT(circ)->used_legacy_circuit_handshake) {
+      is_v2 = true;
+    } else if (TO_OR_CIRCUIT(circ)->rend_splice) {
+      /* If this is a client->RP circuit we need to check the spliced circuit
+       * (which is the service->RP circuit) to see if it was using TAP and
+       * hence if it's a v2 circuit. That's because client->RP circuits can
+       * still use ntor even on v2; but service->RP will always use TAP. */
+      or_circuit_t *splice = TO_OR_CIRCUIT(circ)->rend_splice;
+      if (splice->used_legacy_circuit_handshake) {
+        is_v2 = true;
+      }
+    }
+    rep_hist_seen_new_rp_cell(is_v2);
   }
 }
 
diff --git a/src/core/or/or_circuit_st.h b/src/core/or/or_circuit_st.h
index 4e17b1c143..4da88889ce 100644
--- a/src/core/or/or_circuit_st.h
+++ b/src/core/or/or_circuit_st.h
@@ -63,6 +63,12 @@ struct or_circuit_t {
    *  statistics. */
   unsigned int circuit_carries_hs_traffic_stats : 1;
 
+  /** True iff this circuit was made with a CREATE_FAST cell, or a CREATE[2]
+   * cell with a TAP handshake. If this is the case and this is a rend circuit,
+   * this is a v2 circuit, otherwise if this is a rend circuit it's a v3
+   * circuit. */
+  bool used_legacy_circuit_handshake;
+
   /** Number of cells that were removed from circuit queue; reset every
    * time when writing buffer stats to disk. */
   uint32_t processed_cells;
diff --git a/src/feature/stats/rephist.c b/src/feature/stats/rephist.c
index 5858f14245..2ad86ff6d9 100644
--- a/src/feature/stats/rephist.c
+++ b/src/feature/stats/rephist.c
@@ -1932,6 +1932,20 @@ rep_hist_hsdir_stored_maybe_new_v3_onion(const uint8_t *blinded_key)
   }
 }
 
+/** We saw a new HS relay cell: count it!
+ *  If <b>is_v2</b> is set then it's a v2 RP cell, otherwise it's a v3. */
+void
+rep_hist_seen_new_rp_cell(bool is_v2)
+{
+  log_debug(LD_GENERAL, "New RP cell (%d)", is_v2);
+
+  if (is_v2 && hs_v2_stats) {
+    hs_v2_stats->rp_v2_relay_cells_seen++;
+  } else if (!is_v2 && hs_v3_stats && should_collect_v3_stats()) {
+    hs_v3_stats->rp_v3_relay_cells_seen++;
+  }
+}
+
 /* The number of cells that are supposed to be hidden from the adversary
  * by adding noise from the Laplace distribution.  This value, divided by
  * EPSILON, is Laplace parameter b. It must be greather than 0. */
diff --git a/src/feature/stats/rephist.h b/src/feature/stats/rephist.h
index 5873594781..3bb4f996a2 100644
--- a/src/feature/stats/rephist.h
+++ b/src/feature/stats/rephist.h
@@ -66,7 +66,7 @@ MOCK_DECL(int, rep_hist_get_circuit_handshake_assigned, (uint16_t type));
 void rep_hist_hs_v2_stats_init(time_t now);
 time_t rep_hist_hs_v2_stats_write(time_t now);
 char *rep_hist_get_hs_v2_stats_string(void);
-void rep_hist_seen_new_rp_cell(void);
+void rep_hist_seen_new_rp_cell(bool is_v2);
 void rep_hist_hsdir_stored_maybe_new_v2_onion(const crypto_pk_t *pubkey);
 
 time_t rep_hist_hs_v3_stats_write(time_t now);