From 0222fc4d714c709fa8a0cee1227805a0e23b18d9 Mon Sep 17 00:00:00 2001
From: trinity-1686a <trinity@deuxfleurs.fr>
Date: Sun, 5 Mar 2023 19:43:09 +0100
Subject: [PATCH 1/2] add new metrics entry for cert expiration

---
 src/feature/relay/relay_metrics.c | 32 +++++++++++++++++++++++++++++++
 src/feature/relay/relay_metrics.h |  2 ++
 2 files changed, 34 insertions(+)

diff --git a/src/feature/relay/relay_metrics.c b/src/feature/relay/relay_metrics.c
index cdf34a3404..2e68475f29 100644
--- a/src/feature/relay/relay_metrics.c
+++ b/src/feature/relay/relay_metrics.c
@@ -32,8 +32,10 @@
 #include "feature/nodelist/nodelist.h"
 #include "feature/nodelist/node_st.h"
 #include "feature/nodelist/routerstatus_st.h"
+#include "feature/nodelist/torcert.h"
 #include "feature/relay/relay_metrics.h"
 #include "feature/relay/router.h"
+#include "feature/relay/routerkeys.h"
 #include "feature/stats/rephist.h"
 
 #include <event2/dns.h>
@@ -55,6 +57,7 @@ static void fill_streams_values(void);
 static void fill_relay_flags(void);
 static void fill_tcp_exhaustion_values(void);
 static void fill_traffic_values(void);
+static void fill_signing_cert_expiry(void);
 
 /** The base metrics that is a static array of metrics added to the metrics
  * store.
@@ -174,6 +177,13 @@ static const relay_metrics_entry_t base_metrics[] =
     .help = "Total number of circuits",
     .fill_fn = fill_circuits_values,
   },
+  {
+    .key = RELAY_METRICS_SIGNING_CERT_EXPIRY,
+    .type = METRICS_TYPE_GAUGE,
+    .name = METRICS_NAME(relay_signing_cert_expiry_timestamp),
+    .help = "Timestamp at which the current online keys will expire",
+    .fill_fn = fill_signing_cert_expiry,
+  },
 };
 static const size_t num_base_metrics = ARRAY_LENGTH(base_metrics);
 
@@ -991,6 +1001,28 @@ fill_oom_values(void)
   metrics_store_entry_update(sentry, oom_stats_n_bytes_removed_hsdir);
 }
 
+/** Fill function for the RELAY_METRICS_SIGNING_CERT_EXPIRY metrics. */
+static void
+fill_signing_cert_expiry(void)
+{
+  metrics_store_entry_t *sentry;
+  const tor_cert_t *signing_key;
+  const relay_metrics_entry_t *rentry =
+    &base_metrics[RELAY_METRICS_SIGNING_CERT_EXPIRY];
+  uint64_t valid_until = 0;
+
+  sentry = metrics_store_add(the_store, rentry->type, rentry->name,
+                             rentry->help);
+
+  if (get_options()->OfflineMasterKey) {
+    signing_key = get_master_signing_key_cert();
+    if (signing_key) {
+      valid_until = signing_key->valid_until;
+    }
+  }
+  metrics_store_entry_update(sentry, valid_until);
+}
+
 /** Reset the global store and fill it with all the metrics from base_metrics
  * and their associated values.
  *
diff --git a/src/feature/relay/relay_metrics.h b/src/feature/relay/relay_metrics.h
index 1d2d649d8a..100815051b 100644
--- a/src/feature/relay/relay_metrics.h
+++ b/src/feature/relay/relay_metrics.h
@@ -47,6 +47,8 @@ typedef enum {
   RELAY_METRICS_RELAY_FLAGS,
   /** Numer of circuits. */
   RELAY_METRICS_NUM_CIRCUITS,
+  /** Timestamp at which the current online keys will expire. */
+  RELAY_METRICS_SIGNING_CERT_EXPIRY
 } relay_metrics_key_t;
 
 /** The metadata of a relay metric. */

From 0c634999c13bdf40843924d54fc3294136774788 Mon Sep 17 00:00:00 2001
From: trinity-1686a <trinity@deuxfleurs.fr>
Date: Sun, 19 Mar 2023 10:31:28 +0100
Subject: [PATCH 2/2] don't emit key expiration metric instead of setting it to
 zero

---
 src/feature/relay/relay_metrics.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/feature/relay/relay_metrics.c b/src/feature/relay/relay_metrics.c
index 2e68475f29..6ee75f69f0 100644
--- a/src/feature/relay/relay_metrics.c
+++ b/src/feature/relay/relay_metrics.c
@@ -1009,18 +1009,15 @@ fill_signing_cert_expiry(void)
   const tor_cert_t *signing_key;
   const relay_metrics_entry_t *rentry =
     &base_metrics[RELAY_METRICS_SIGNING_CERT_EXPIRY];
-  uint64_t valid_until = 0;
-
-  sentry = metrics_store_add(the_store, rentry->type, rentry->name,
-                             rentry->help);
 
   if (get_options()->OfflineMasterKey) {
     signing_key = get_master_signing_key_cert();
     if (signing_key) {
-      valid_until = signing_key->valid_until;
+      sentry = metrics_store_add(the_store, rentry->type, rentry->name,
+                                 rentry->help);
+      metrics_store_entry_update(sentry, signing_key->valid_until);
     }
   }
-  metrics_store_entry_update(sentry, valid_until);
 }
 
 /** Reset the global store and fill it with all the metrics from base_metrics