Only mark timers to update

Timers are updated on every single packet call, but their
accuracy is limited to 250ms where currentTime is updated.
So just mark timers to update, and update them only once in
update_timers.

neptun/src/noise/mod.rs

@@ -276,10 +276,10 @@ impl Tunn {
         if let Some(ref session) = self.sessions[current % N_SESSIONS] {
             // Send the packet using an established session
             let packet = session.format_packet_data(src, dst);
-            self.timer_tick(TimerName::TimeLastPacketSent);
+            self.mark_timer_to_update(TimerName::TimeLastPacketSent);
             // Exclude Keepalive packets from timer update.
             if !src.is_empty() {
-                self.timer_tick(TimerName::TimeLastDataPacketSent);
+                self.mark_timer_to_update(TimerName::TimeLastPacketSent);
             }
             self.tx_bytes += packet.len();
             return TunnResult::WriteToNetwork(packet);
@@ -365,8 +365,8 @@ impl Tunn {
         let index = session.local_index();
         self.sessions[index % N_SESSIONS] = Some(session);
 
-        self.timer_tick(TimerName::TimeLastPacketReceived);
-        self.timer_tick(TimerName::TimeLastPacketSent);
+        self.mark_timer_to_update(TimerName::TimeLastPacketReceived);
+        self.mark_timer_to_update(TimerName::TimeLastPacketSent);
         self.timer_tick_session_established(false, index); // New session established, we are not the initiator
 
         tracing::debug!(message = "Sending handshake_response", local_idx = index);
@@ -399,7 +399,7 @@ impl Tunn {
         let index = l_idx % N_SESSIONS;
         self.sessions[index] = Some(session);
 
-        self.timer_tick(TimerName::TimeLastPacketReceived);
+        self.mark_timer_to_update(TimerName::TimeLastPacketReceived);
         self.timer_tick_session_established(true, index); // New session established, we are the initiator
         self.set_current_session(l_idx);
 
@@ -424,8 +424,8 @@ impl Tunn {
         // Increase the rx_bytes accordingly
         self.rx_bytes += COOKIE_REPLY_SZ;
 
-        self.timer_tick(TimerName::TimeLastPacketReceived);
-        self.timer_tick(TimerName::TimeCookieReceived);
+        self.mark_timer_to_update(TimerName::TimeLastPacketReceived);
+        self.mark_timer_to_update(TimerName::TimeCookieReceived);
 
         tracing::debug!("Did set cookie");
 
@@ -469,7 +469,7 @@ impl Tunn {
 
         self.set_current_session(r_idx);
 
-        self.timer_tick(TimerName::TimeLastPacketReceived);
+        self.mark_timer_to_update(TimerName::TimeLastPacketReceived);
 
         Ok(self.validate_decapsulated_packet(decapsulated_packet))
     }
@@ -496,9 +496,9 @@ impl Tunn {
                 tracing::debug!("Sending handshake_initiation");
 
                 if starting_new_handshake {
-                    self.timer_tick(TimerName::TimeLastHandshakeStarted);
+                    self.mark_timer_to_update(TimerName::TimeLastHandshakeStarted);
                 }
-                self.timer_tick(TimerName::TimeLastPacketSent);
+                self.mark_timer_to_update(TimerName::TimeLastPacketSent);
                 self.tx_bytes += packet.len();
 
                 TunnResult::WriteToNetwork(packet)
@@ -548,7 +548,7 @@ impl Tunn {
             return TunnResult::Err(WireGuardError::InvalidPacket);
         }
 
-        self.timer_tick(TimerName::TimeLastDataPacketReceived);
+        self.mark_timer_to_update(TimerName::TimeLastDataPacketReceived);
         self.rx_bytes += message_data_len(computed_len);
 
         match src_ip_address {

neptun/src/noise/timers.rs

@@ -6,6 +6,7 @@ use super::errors::WireGuardError;
 use crate::noise::{safe_duration::SafeDuration as Duration, Tunn, TunnResult};
 use std::mem;
 use std::ops::{Index, IndexMut};
+use std::sync::atomic::AtomicU16;
 use std::time::SystemTime;
 
 #[cfg(feature = "mock-instant")]
@@ -42,7 +43,7 @@ pub(crate) const REKEY_TIMEOUT: Duration = Duration::from_secs(5);
 const KEEPALIVE_TIMEOUT: Duration = Duration::from_secs(10);
 const COOKIE_EXPIRATION_TIME: Duration = Duration::from_secs(120);
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Copy)]
 pub enum TimerName {
     /// Current time, updated each call to `update_timers`
     TimeCurrent,
@@ -65,6 +66,20 @@ pub enum TimerName {
     Top,
 }
 
+impl TimerName {
+    pub const VALUES: [Self; TimerName::Top as usize] = [
+        Self::TimeCurrent,
+        Self::TimeSessionEstablished,
+        Self::TimeLastHandshakeStarted,
+        Self::TimeLastPacketReceived,
+        Self::TimeLastPacketSent,
+        Self::TimeLastDataPacketReceived,
+        Self::TimeLastDataPacketSent,
+        Self::TimeCookieReceived,
+        Self::TimePersistentKeepalive,
+    ];
+}
+
 use self::TimerName::*;
 
 #[derive(Debug)]
@@ -82,6 +97,7 @@ pub struct Timers {
     persistent_keepalive: usize,
     /// Should this timer call reset rr function (if not a shared rr instance)
     pub(super) should_reset_rr: bool,
+    timers_to_update_mask: AtomicU16,
 }
 
 impl Timers {
@@ -95,6 +111,7 @@ impl Timers {
             want_handshake_since: Default::default(),
             persistent_keepalive: usize::from(persistent_keepalive.unwrap_or(0)),
             should_reset_rr: reset_rr,
+            timers_to_update_mask: Default::default(),
         }
     }
 
@@ -128,7 +145,13 @@ impl IndexMut<TimerName> for Timers {
 }
 
 impl Tunn {
-    pub(super) fn timer_tick(&mut self, timer_name: TimerName) {
+    pub(super) fn mark_timer_to_update(&self, timer_name: TimerName) {
+        self.timers
+            .timers_to_update_mask
+            .fetch_or(1 << timer_name as u16, std::sync::atomic::Ordering::Relaxed);
+    }
+
+    fn timer_tick(&mut self, timer_name: TimerName) {
         let time = self.timers[TimeCurrent];
         match timer_name {
             TimeLastPacketReceived => {
@@ -207,6 +230,17 @@ impl Tunn {
         let now = time.duration_since(self.timers.time_started).into();
         self.timers[TimeCurrent] = now;
 
+        // Check which timers to update, and update them
+        let timer_mask = self
+            .timers
+            .timers_to_update_mask
+            .load(std::sync::atomic::Ordering::Relaxed);
+        for timer_name in TimerName::VALUES {
+            if (timer_mask & (1 << (timer_name as u16))) != 0 {
+                self.timer_tick(timer_name);
+            }
+        }
+
         self.update_session_timers(now);
 
         // Load timers only once:
@@ -380,3 +414,39 @@ impl Tunn {
         self.timers.persistent_keepalive = keepalive as usize;
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use rand::RngCore;
+    use rand_core::OsRng;
+
+    use crate::noise::Tunn;
+
+    use super::TimerName;
+
+    #[test]
+    fn create_two_tuns() {
+        let my_secret_key = x25519_dalek::StaticSecret::random_from_rng(OsRng);
+        let my_idx = OsRng.next_u32();
+
+        let their_secret_key = x25519_dalek::StaticSecret::random_from_rng(OsRng);
+        let their_public_key = x25519_dalek::PublicKey::from(&their_secret_key);
+
+        let mut my_tun =
+            Tunn::new(my_secret_key, their_public_key, None, None, my_idx, None).unwrap();
+
+        my_tun.mark_timer_to_update(super::TimerName::TimeLastDataPacketSent);
+        my_tun.mark_timer_to_update(super::TimerName::TimeLastDataPacketReceived);
+        my_tun.mark_timer_to_update(super::TimerName::TimePersistentKeepalive);
+
+        my_tun.update_timers(&mut [0]);
+
+        assert!(!my_tun.timers[TimerName::TimeLastDataPacketSent].is_zero());
+        assert!(!my_tun.timers[TimerName::TimeLastDataPacketReceived].is_zero());
+        assert!(!my_tun.timers[TimerName::TimePersistentKeepalive].is_zero());
+
+        assert!(my_tun.timers[TimerName::TimeCookieReceived].is_zero());
+        assert!(my_tun.timers[TimerName::TimeLastHandshakeStarted].is_zero());
+        assert!(my_tun.timers[TimerName::TimeLastPacketReceived].is_zero());
+    }
+}