Implement support for "unique v3 onions" stat.

src/feature/hs/hs_cache.c

@@ -175,7 +175,10 @@ cache_store_v3_as_dir(hs_cache_dir_descriptor_t *desc)
    * old HS protocol cache subsystem for which we are tied with. */
   rend_cache_increment_allocation(cache_get_dir_entry_size(desc));
 
-  /* XXX: Update HS statistics. We should have specific stats for v3. */
+  /* Update HSv3 statistics */
+  if (get_options()->HiddenServiceStatistics) {
+    rep_hist_hsdir_stored_maybe_new_v3_onion(desc->key);
+  }
 
   return 0;
 

src/feature/stats/rephist.c

@@ -1789,9 +1789,8 @@ rep_hist_seen_new_rp_cell(void)
   hs_v2_stats->rp_relay_cells_seen++;
 }
 
-/** As HSDirs, we saw another hidden service with public key
- *  <b>pubkey</b>. Check whether we have counted it before, if not
- *  count it now! */
+/** As HSDirs, we saw another v2 onion with public key <b>pubkey</b>. Check
+ *  whether we have counted it before, if not count it now! */
 void
 rep_hist_hsdir_stored_maybe_new_v2_onion(const crypto_pk_t *pubkey)
 {
@@ -1908,6 +1907,31 @@ should_collect_v3_stats(void)
   return start_of_hs_v3_stats_interval <= approx_time();
 }
 
+/** We just received a new descriptor with <b>blinded_key</b>. See if we've
+ * seen this blinded key before, and if not add it to the stats.  */
+void
+rep_hist_hsdir_stored_maybe_new_v3_onion(const uint8_t *blinded_key)
+{
+  /* Return early if we don't collect HSv3 stats, or if it's not yet the time
+   * to collect them. */
+  if (!hs_v3_stats || !should_collect_v3_stats()) {
+    return;
+  }
+
+  bool seen_before = !!digestmap_get(hs_v3_stats->v3_onions_seen_this_period,
+                                     (char*)blinded_key);
+
+  log_info(LD_GENERAL, "Considering v3 descriptor with %s (%sseen before)",
+           safe_str(hex_str((char*)blinded_key, 32)),
+           seen_before ? "" : "not ");
+
+  /* Count it if we haven't seen it before. */
+  if (!seen_before) {
+    digestmap_set(hs_v3_stats->v3_onions_seen_this_period,
+                  (char*)blinded_key, (void*)(uintptr_t)1);
+  }
+}
+
 /* 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. */

src/feature/stats/rephist.h

@@ -71,6 +71,7 @@ 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);
 char *rep_hist_get_hs_v3_stats_string(void);
+void rep_hist_hsdir_stored_maybe_new_v3_onion(const uint8_t *blinded_key);
 
 void rep_hist_free_all(void);