metrics: Add metrics for rendezvous and introduction request failures.

This introduces a couple of new service side metrics:
* `hs_intro_rejected_intro_req_count`, which counts the number of introduction
  requests rejected by the hidden service
* `hs_rdv_error_count`, which counts the number of rendezvous errors as seen by
  the hidden service (this number includes the number of circuit establishment
  failures, failed retries, end-to-end circuit setup failures)

Closes #40755. This partially addresses #40717.

Signed-off-by: Gabriela Moldovan <gabi@torproject.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/test/test_hs_metrics.c b/src/test/test_hs_metrics.c
index 8625933df7..03f6aedbb4 100644
--- a/src/test/test_hs_metrics.c
+++ b/src/test/test_hs_metrics.c
@@ -56,6 +56,23 @@ test_metrics(void *arg)
                                service, 0, 42);
   tt_int_op(metrics_store_entry_get_value(entry), OP_EQ, 84);
 
+  /* Update tor_hs_intro_rejected_intro_req_count */
+  hs_metrics_update_by_ident(HS_METRICS_NUM_REJECTED_INTRO_REQ,
+                             &service->keys.identity_pk, 0, 112);
+
+  entries = metrics_store_get_all(service->metrics.store,
+                                  "tor_hs_intro_rejected_intro_req_count");
+  tt_assert(entries);
+  tt_int_op(smartlist_len(entries), OP_EQ, 1);
+  entry = smartlist_get(entries, 0);
+  tt_assert(entry);
+  tt_int_op(metrics_store_entry_get_value(entry), OP_EQ, 112);
+
+  /* Update tor_hs_intro_rejected_intro_req_count entry by service now. */
+  hs_metrics_update_by_service(HS_METRICS_NUM_REJECTED_INTRO_REQ,
+                               service, 0, 10);
+  tt_int_op(metrics_store_entry_get_value(entry), OP_EQ, 122);
+
  done:
   hs_free_all();
 }