Make MIN_ONION_KEY_LIFETIME a consensus parameter defined value.

This patch turns `MIN_ONION_KEY_LIFETIME` into a new function
`get_onion_key_lifetime()` which gets its value from a network consensus
parameter named "onion-key-rotation-days". This allows us to tune the
value at a later point in time with no code modifications.

We also bump the default onion key lifetime from 7 to 28 days as per
proposal #274.

See: https://bugs.torproject.org/21641

1 files changed, 6 insertions, 5 deletions

diff --git a/src/or/main.c b/src/or/main.c
index 475587eacd..107a4842a9 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -1472,15 +1472,16 @@ run_scheduled_events(time_t now)
     pt_configure_remaining_proxies();
 }
 
-/* Periodic callback: Every MIN_ONION_KEY_LIFETIME seconds, rotate the onion
- * keys, shut down and restart all cpuworkers, and update our descriptor if
- * necessary.
+/* Periodic callback: rotate the onion keys after the period defined by the
+ * "onion-key-rotation-days" consensus parameter, shut down and restart all
+ * cpuworkers, and update our descriptor if necessary.
  */
 static int
 rotate_onion_key_callback(time_t now, const or_options_t *options)
 {
   if (server_mode(options)) {
-    time_t rotation_time = get_onion_key_set_at()+MIN_ONION_KEY_LIFETIME;
+    int onion_key_lifetime = get_onion_key_lifetime();
+    time_t rotation_time = get_onion_key_set_at()+onion_key_lifetime;
     if (rotation_time > now) {
       return safe_timer_diff(now, rotation_time);
     }
@@ -1493,7 +1494,7 @@ rotate_onion_key_callback(time_t now, const or_options_t *options)
     }
     if (advertised_server_mode() && !options->DisableNetwork)
       router_upload_dir_desc_to_dirservers(0);
-    return MIN_ONION_KEY_LIFETIME;
+    return onion_key_lifetime;
   }
   return PERIODIC_EVENT_NO_UPDATE;
 }