metrics: Add a `reason` label to the HS error metrics.

This adds a `reason` label to the `hs_intro_rejected_intro_req_count` and
`hs_rdv_error_count` metrics introduced in #40755.

Metric look up and intialization is now more a bit more involved. This may be
fine for now, but it will become unwieldy if/when we add more labels (and as
such will need to be refactored).

Also, in the future, we may want to introduce finer grained `reason` labels.
For example, the `invalid_introduce2` label actually covers multiple types of
errors that can happen during the processing of an INTRODUCE2 cell (such as
cell parse errors, replays, decryption errors).

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

1 files changed, 23 insertions, 17 deletions

diff --git a/src/feature/hs/hs_metrics.h b/src/feature/hs/hs_metrics.h
index db02fefcea..a32f76e3bc 100644
--- a/src/feature/hs/hs_metrics.h
+++ b/src/feature/hs/hs_metrics.h
@@ -26,53 +26,59 @@ const smartlist_t *hs_metrics_get_stores(void);
 /* Metrics Update. */
 void hs_metrics_update_by_ident(const hs_metrics_key_t key,
                                 const ed25519_public_key_t *ident_pk,
-                                const uint16_t port, int64_t n);
+                                const uint16_t port, const char *reason,
+                                int64_t n);
 void hs_metrics_update_by_service(const hs_metrics_key_t key,
                                   const hs_service_t *service,
-                                  uint16_t port, int64_t n);
+                                  uint16_t port, const char *reason,
+                                  int64_t n);
 
 /** New introducion request received. */
 #define hs_metrics_new_introduction(s) \
-  hs_metrics_update_by_service(HS_METRICS_NUM_INTRODUCTIONS, (s), 0, 1)
+  hs_metrics_update_by_service(HS_METRICS_NUM_INTRODUCTIONS, (s), 0, NULL, 1)
 
 /** Introducion request rejected. */
-#define hs_metrics_reject_intro_req(s) \
-  hs_metrics_update_by_service(HS_METRICS_NUM_REJECTED_INTRO_REQ, (s), 0, 1)
+#define hs_metrics_reject_intro_req(s, reason)                            \
+  hs_metrics_update_by_service(HS_METRICS_NUM_REJECTED_INTRO_REQ, (s), 0, \
+                               (reason), 1)
 
 /** Number of bytes written to the application from the service. */
-#define hs_metrics_app_write_bytes(i, port, n) \
-  hs_metrics_update_by_ident(HS_METRICS_APP_WRITE_BYTES, (i), (port), (n))
+#define hs_metrics_app_write_bytes(i, port, n)                              \
+  hs_metrics_update_by_ident(HS_METRICS_APP_WRITE_BYTES, (i), (port), NULL, \
+                             (n))
 
 /** Number of bytes read from the application to the service. */
 #define hs_metrics_app_read_bytes(i, port, n) \
-  hs_metrics_update_by_ident(HS_METRICS_APP_READ_BYTES, (i), (port), (n))
+  hs_metrics_update_by_ident(HS_METRICS_APP_READ_BYTES, (i), (port), NULL, (n))
 
 /** Newly established rendezvous. This is called as soon as the circuit purpose
  * is REND_JOINED which is when the RENDEZVOUS2 cell is sent. */
 #define hs_metrics_new_established_rdv(s) \
-  hs_metrics_update_by_service(HS_METRICS_NUM_ESTABLISHED_RDV, (s), 0, 1)
+  hs_metrics_update_by_service(HS_METRICS_NUM_ESTABLISHED_RDV, (s), 0, NULL, 1)
 
 /** New rendezvous circuit failure. */
-#define hs_metrics_failed_rdv(i) \
-  hs_metrics_update_by_ident(HS_METRICS_NUM_FAILED_RDV, (i), 0, 1)
+#define hs_metrics_failed_rdv(i, reason) \
+  hs_metrics_update_by_ident(HS_METRICS_NUM_FAILED_RDV, (i), 0, (reason), 1)
 
 /** Established rendezvous closed. This is called when the circuit in
  * REND_JOINED state is marked for close. */
 #define hs_metrics_close_established_rdv(i) \
-  hs_metrics_update_by_ident(HS_METRICS_NUM_ESTABLISHED_RDV, (i), 0, -1)
+  hs_metrics_update_by_ident(HS_METRICS_NUM_ESTABLISHED_RDV, (i), 0, NULL, -1)
 
 /** New rendezvous circuit being launched. */
 #define hs_metrics_new_rdv(i) \
-  hs_metrics_update_by_ident(HS_METRICS_NUM_RDV, (i), 0, 1)
+  hs_metrics_update_by_ident(HS_METRICS_NUM_RDV, (i), 0, NULL, 1)
 
 /** New introduction circuit has been established. This is called when the
  * INTRO_ESTABLISHED has been received by the service. */
-#define hs_metrics_new_established_intro(s) \
-  hs_metrics_update_by_service(HS_METRICS_NUM_ESTABLISHED_INTRO, (s), 0, 1)
+#define hs_metrics_new_established_intro(s)                              \
+  hs_metrics_update_by_service(HS_METRICS_NUM_ESTABLISHED_INTRO, (s), 0, \
+                               NULL, 1)
 
 /** Established introduction circuit closes. This is called when
  * INTRO_ESTABLISHED circuit is marked for close. */
-#define hs_metrics_close_established_intro(i) \
-  hs_metrics_update_by_ident(HS_METRICS_NUM_ESTABLISHED_INTRO, (i), 0, -1)
+#define hs_metrics_close_established_intro(i)                                \
+  hs_metrics_update_by_ident(HS_METRICS_NUM_ESTABLISHED_INTRO, (i), 0, NULL, \
+                             -1)
 
 #endif /* !defined(TOR_FEATURE_HS_HS_METRICS_H) */