relay: Add connection stats to MetricsPort

This adds the number of created and opened connections to the
MetricsPort for a relay for each connection type and direction.

Output looks like:

  # HELP tor_relay_connections Connections metrics of this relay
  # TYPE tor_relay_connections counter
  tor_relay_connections{type="OR listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="OR listener",direction="received",state="created"} 0
  tor_relay_connections{type="OR listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="OR listener",direction="received",state="opened"} 0
  tor_relay_connections{type="OR",direction="initiated",state="created"} 5
  tor_relay_connections{type="OR",direction="received",state="created"} 0
  tor_relay_connections{type="OR",direction="initiated",state="opened"} 5
  tor_relay_connections{type="OR",direction="received",state="opened"} 0
  tor_relay_connections{type="Exit",direction="initiated",state="created"} 0
  tor_relay_connections{type="Exit",direction="received",state="created"} 0
  tor_relay_connections{type="Exit",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Exit",direction="received",state="opened"} 0
  tor_relay_connections{type="Socks listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Socks listener",direction="received",state="created"} 0
  tor_relay_connections{type="Socks listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Socks listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Socks",direction="initiated",state="created"} 0
  tor_relay_connections{type="Socks",direction="received",state="created"} 0
  tor_relay_connections{type="Socks",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Socks",direction="received",state="opened"} 0
  tor_relay_connections{type="Directory listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Directory listener",direction="received",state="created"} 0
  tor_relay_connections{type="Directory listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Directory listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Directory",direction="initiated",state="created"} 0
  tor_relay_connections{type="Directory",direction="received",state="created"} 0
  tor_relay_connections{type="Directory",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Directory",direction="received",state="opened"} 0
  tor_relay_connections{type="Control listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Control listener",direction="received",state="created"} 0
  tor_relay_connections{type="Control listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Control listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Control",direction="initiated",state="created"} 0
  tor_relay_connections{type="Control",direction="received",state="created"} 0
  tor_relay_connections{type="Control",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Control",direction="received",state="opened"} 0
  tor_relay_connections{type="Transparent pf/netfilter listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Transparent pf/netfilter listener",direction="received",state="created"} 0
  tor_relay_connections{type="Transparent pf/netfilter listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Transparent pf/netfilter listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Transparent natd listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Transparent natd listener",direction="received",state="created"} 0
  tor_relay_connections{type="Transparent natd listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Transparent natd listener",direction="received",state="opened"} 0
  tor_relay_connections{type="DNS listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="DNS listener",direction="received",state="created"} 0
  tor_relay_connections{type="DNS listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="DNS listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Extended OR",direction="initiated",state="created"} 0
  tor_relay_connections{type="Extended OR",direction="received",state="created"} 0
  tor_relay_connections{type="Extended OR",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Extended OR",direction="received",state="opened"} 0
  tor_relay_connections{type="Extended OR listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Extended OR listener",direction="received",state="created"} 0
  tor_relay_connections{type="Extended OR listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Extended OR listener",direction="received",state="opened"} 0
  tor_relay_connections{type="HTTP tunnel listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="HTTP tunnel listener",direction="received",state="created"} 0
  tor_relay_connections{type="HTTP tunnel listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="HTTP tunnel listener",direction="received",state="opened"} 0
  tor_relay_connections{type="Metrics listener",direction="initiated",state="created"} 0
  tor_relay_connections{type="Metrics listener",direction="received",state="created"} 1
  tor_relay_connections{type="Metrics listener",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Metrics listener",direction="received",state="opened"} 1
  tor_relay_connections{type="Metrics",direction="initiated",state="created"} 0
  tor_relay_connections{type="Metrics",direction="received",state="created"} 0
  tor_relay_connections{type="Metrics",direction="initiated",state="opened"} 0
  tor_relay_connections{type="Metrics",direction="received",state="opened"} 0

Related to #40194

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/src/feature/relay/relay_metrics.c b/src/feature/relay/relay_metrics.c
index 908cfdb0d9..efe77473aa 100644
--- a/src/feature/relay/relay_metrics.c
+++ b/src/feature/relay/relay_metrics.c
@@ -11,6 +11,7 @@
 #include "orconfig.h"
 
 #include "core/or/or.h"
+#include "core/mainloop/connection.h"
 #include "core/or/relay.h"
 
 #include "lib/malloc/malloc.h"
@@ -24,6 +25,7 @@
 #include <event2/dns.h>
 
 /** Declarations of each fill function for metrics defined in base_metrics. */
+static void fill_connections_values(void);
 static void fill_dns_error_values(void);
 static void fill_dns_query_values(void);
 static void fill_global_bw_limit_values(void);
@@ -87,6 +89,13 @@ static const relay_metrics_entry_t base_metrics[] =
     .help = "Total number of times we ran out of TCP ports",
     .fill_fn = fill_tcp_exhaustion_values,
   },
+  {
+    .key = RELAY_METRICS_NUM_CONNECTIONS,
+    .type = METRICS_TYPE_COUNTER,
+    .name = METRICS_NAME(relay_connections),
+    .help = "Connections metrics of this relay",
+    .fill_fn = fill_connections_values,
+  },
 };
 static const size_t num_base_metrics = ARRAY_LENGTH(base_metrics);
 
@@ -113,6 +122,57 @@ handshake_type_to_str(const uint16_t type)
   }
 }
 
+/** Helper: Fill in single connection metrics output. */
+static void
+fill_single_connection_value(metrics_store_entry_t *sentry,
+                             unsigned int conn_type,
+                             const char* direction,
+                             const char* state,
+                             uint64_t value)
+{
+  metrics_store_entry_add_label(sentry,
+          metrics_format_label("type", conn_type_to_string(conn_type)));
+  metrics_store_entry_add_label(sentry,
+          metrics_format_label("direction", direction));
+  metrics_store_entry_add_label(sentry,
+          metrics_format_label("state", state));
+  metrics_store_entry_update(sentry, value);
+}
+
+/** Fill function for the RELAY_METRICS_NUM_CONNECTIONS metric. */
+static void
+fill_connections_values(void)
+{
+  const relay_metrics_entry_t *rentry =
+    &base_metrics[RELAY_METRICS_NUM_CONNECTIONS];
+
+  for (unsigned int i = CONN_TYPE_MIN_; i < CONN_TYPE_MAX_ ; i++) {
+    /* Type is unused. Ugly but else we clobber the output. */
+    if (i == 10) {
+      continue;
+    }
+    metrics_store_entry_t *sentry =
+      metrics_store_add(the_store, rentry->type, rentry->name, rentry->help);
+    fill_single_connection_value(sentry, i, "initiated", "created",
+                                 rep_hist_get_conn_created(false, i));
+
+    sentry = metrics_store_add(the_store, rentry->type, rentry->name,
+                               rentry->help);
+    fill_single_connection_value(sentry, i, "received", "created",
+                                 rep_hist_get_conn_created(true, i));
+
+    sentry = metrics_store_add(the_store, rentry->type, rentry->name,
+                               rentry->help);
+    fill_single_connection_value(sentry, i, "initiated", "opened",
+                                 rep_hist_get_conn_opened(false, i));
+
+    sentry = metrics_store_add(the_store, rentry->type, rentry->name,
+                               rentry->help);
+    fill_single_connection_value(sentry, i, "received", "opened",
+                                 rep_hist_get_conn_opened(true, i));
+  }
+}
+
 /** Fill function for the RELAY_METRICS_NUM_DNS metrics. */
 static void
 fill_tcp_exhaustion_values(void)