Improve v3 onion service logging for intro and rend points

Diagnostics for #23820.

src/or/hs_circuit.c

@@ -343,6 +343,17 @@ send_establish_intro(const hs_service_t *service,
   memwipe(payload, 0, sizeof(payload));
 }
 
+/* Return a string constant describing the anonymity of service. */
+static const char *
+get_service_anonymity_string(const hs_service_t *service)
+{
+  if (service->config.is_single_onion) {
+    return "single onion";
+  } else {
+    return "hidden";
+  }
+}
+
 /* For a given service, the ntor onion key and a rendezvous cookie, launch a
  * circuit to the rendezvous point specified by the link specifiers. On
  * success, a circuit identifier is attached to the circuit with the needed
@@ -370,7 +381,15 @@ launch_rendezvous_point_circuit(const hs_service_t *service,
                                         &data->onion_pk,
                                         service->config.is_single_onion);
   if (info == NULL) {
-    /* We are done here, we can't extend to the rendezvous point. */
+    /* We are done here, we can't extend to the rendezvous point.
+     * If you're running an IPv6-only v3 single onion service on 0.3.2 or with
+     * 0.3.2 clients, and somehow disable the option check, it will fail here.
+     */
+    log_fn(LOG_PROTOCOL_WARN, LD_REND,
+           "Not enough info to open a circuit to a rendezvous point for "
+           "%s service %s.",
+           get_service_anonymity_string(service),
+           safe_str_client(service->onion_address));
     goto end;
   }
 
@@ -392,17 +411,19 @@ launch_rendezvous_point_circuit(const hs_service_t *service,
     }
   }
   if (circ == NULL) {
-    log_warn(LD_REND, "Giving up on launching rendezvous circuit to %s "
-                      "for service %s",
+    log_warn(LD_REND, "Giving up on launching a rendezvous circuit to %s "
+                      "for %s service %s",
              safe_str_client(extend_info_describe(info)),
+             get_service_anonymity_string(service),
              safe_str_client(service->onion_address));
     goto end;
   }
   log_info(LD_REND, "Rendezvous circuit launched to %s with cookie %s "
-                    "for service %s",
+                    "for %s service %s",
            safe_str_client(extend_info_describe(info)),
            safe_str_client(hex_str((const char *) data->rendezvous_cookie,
                                    REND_COOKIE_LEN)),
+           get_service_anonymity_string(service),
            safe_str_client(service->onion_address));
   tor_assert(circ->build_state);
   /* Rendezvous circuit have a specific timeout for the time spent on trying

src/or/hs_client.c

@@ -727,15 +727,24 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
   const hs_descriptor_t *desc;
   const hs_desc_encrypted_data_t *enc_data;
   const or_options_t *options = get_options();
+  /* Calculate the onion address for logging purposes */
+  char onion_address[HS_SERVICE_ADDR_LEN_BASE32 + 1];
 
   tor_assert(service_pk);
 
   desc = hs_cache_lookup_as_client(service_pk);
+  /* Assume the service is v3 if the descriptor is missing. This is ok,
+   * because we only use the address in log messages */
+  hs_build_address(service_pk,
+                   desc ? desc->plaintext_data.version : HS_VERSION_THREE,
+                   onion_address);
   if (desc == NULL || !hs_client_any_intro_points_usable(service_pk,
                                                          desc)) {
     log_info(LD_REND, "Unable to randomly select an introduction point "
-                      "because descriptor %s.",
-             (desc) ? "doesn't have usable intro point" : "is missing");
+             "for service %s because descriptor %s. We can't connect.",
+             safe_str_client(onion_address),
+             (desc) ? "doesn't have any usable intro points"
+                    : "is missing (assuming v3 onion address)");
     goto end;
   }
 
@@ -763,6 +772,10 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
     if (ei == NULL) {
       /* We can get here for instance if the intro point is a private address
        * and we aren't allowed to extend to those. */
+      log_info(LD_REND, "Unable to select introduction point with auth key %s "
+               "for service %s, because we could not extend to it.",
+               safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key)),
+               safe_str_client(onion_address));
       continue;
     }
 
@@ -791,14 +804,20 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
    * set, we are forced to not use anything. */
   ei = ei_excluded;
   if (options->StrictNodes) {
-    log_warn(LD_REND, "Every introduction points are in the ExcludeNodes set "
-             "and StrictNodes is set. We can't connect.");
+    log_warn(LD_REND, "Every introduction point for service %s is in the "
+             "ExcludeNodes set and StrictNodes is set. We can't connect.",
+             safe_str_client(onion_address));
     extend_info_free(ei);
     ei = NULL;
+  } else {
+    log_fn(LOG_PROTOCOL_WARN, LD_REND, "Every introduction point for service "
+           "%s is unusable or we can't extend to it. We can't connect.",
+           safe_str_client(onion_address));
   }
 
  end:
   smartlist_free(usable_ips);
+  memwipe(onion_address, 0, sizeof(onion_address));
   return ei;
 }