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, 2 insertions, 0 deletions

diff --git a/src/feature/relay/relay_metrics.h b/src/feature/relay/relay_metrics.h
index 00dfeaa624..02b92cd043 100644
--- a/src/feature/relay/relay_metrics.h
+++ b/src/feature/relay/relay_metrics.h
@@ -29,6 +29,8 @@ typedef enum {
   RELAY_METRICS_NUM_DNS_ERRORS = 5,
   /** Number of TCP exhaustion reached. */
   RELAY_METRICS_NUM_TCP_EXHAUSTION = 6,
+  /** Number of connections. */
+  RELAY_METRICS_NUM_CONNECTIONS = 7,
 } relay_metrics_key_t;
 
 /** The metadata of a relay metric. */