Use existing peer count metrics loop to check for open_nat toggle (#6800)

* implement update_nat_open function in network_behaviour for tracking incoming peers below a given threshold count

* implement update_nat_open function in network_behaviour for tracking incoming peers below a given threshold count

* tidy logic and comments

* move logic to existing metrics loop

* revert change to network_behaviour protocol check

* clippy

* clippy matches! macro

* pull nat_open check outside of peercounting loop

* missing close bracket

* make threshold const

Author: jking-aus

beacon_node/lighthouse_network/src/peer_manager/mod.rs

@@ -63,6 +63,8 @@ pub const MIN_OUTBOUND_ONLY_FACTOR: f32 = 0.2;
 /// limit is 55, and we are at 55 peers, the following parameter provisions a few more slots of
 /// dialing priority peers we need for validator duties.
 pub const PRIORITY_PEER_EXCESS: f32 = 0.2;
+/// The numbre of inbound libp2p peers we have seen before we consider our NAT to be open.
+pub const LIBP2P_NAT_OPEN_THRESHOLD: usize = 3;
 
 /// The main struct that handles peer's reputation and connection status.
 pub struct PeerManager<E: EthSpec> {
@@ -1307,7 +1309,9 @@ impl<E: EthSpec> PeerManager<E> {
     fn update_peer_count_metrics(&self) {
         let mut peers_connected = 0;
         let mut clients_per_peer = HashMap::new();
-        let mut peers_connected_mutli: HashMap<(&str, &str), i32> = HashMap::new();
+        let mut inbound_ipv4_peers_connected: usize = 0;
+        let mut inbound_ipv6_peers_connected: usize = 0;
+        let mut peers_connected_multi: HashMap<(&str, &str), i32> = HashMap::new();
         let mut peers_per_custody_subnet_count: HashMap<u64, i64> = HashMap::new();
 
         for (_, peer_info) in self.network_globals.peers.read().connected_peers() {
@@ -1336,7 +1340,7 @@ impl<E: EthSpec> PeerManager<E> {
                     })
                 })
                 .unwrap_or("unknown");
-            *peers_connected_mutli
+            *peers_connected_multi
                 .entry((direction, transport))
                 .or_default() += 1;
 
@@ -1345,6 +1349,29 @@ impl<E: EthSpec> PeerManager<E> {
                     .entry(meta_data.custody_subnet_count)
                     .or_default() += 1;
             }
+            // Check if incoming peer is ipv4
+            if peer_info.is_incoming_ipv4_connection() {
+                inbound_ipv4_peers_connected += 1;
+            }
+
+            // Check if incoming peer is ipv6
+            if peer_info.is_incoming_ipv6_connection() {
+                inbound_ipv6_peers_connected += 1;
+            }
+        }
+
+        // Set ipv4 nat_open metric flag if threshold of peercount is met, unset if below threshold
+        if inbound_ipv4_peers_connected >= LIBP2P_NAT_OPEN_THRESHOLD {
+            metrics::set_gauge_vec(&metrics::NAT_OPEN, &["libp2p_ipv4"], 1);
+        } else {
+            metrics::set_gauge_vec(&metrics::NAT_OPEN, &["libp2p_ipv4"], 0);
+        }
+
+        // Set ipv6 nat_open metric flag if threshold of peercount is met, unset if below threshold
+        if inbound_ipv6_peers_connected >= LIBP2P_NAT_OPEN_THRESHOLD {
+            metrics::set_gauge_vec(&metrics::NAT_OPEN, &["libp2p_ipv6"], 1);
+        } else {
+            metrics::set_gauge_vec(&metrics::NAT_OPEN, &["libp2p_ipv6"], 0);
         }
 
         // PEERS_CONNECTED
@@ -1375,7 +1402,7 @@ impl<E: EthSpec> PeerManager<E> {
                 metrics::set_gauge_vec(
                     &metrics::PEERS_CONNECTED_MULTI,
                     &[direction, transport],
-                    *peers_connected_mutli
+                    *peers_connected_multi
                         .get(&(direction, transport))
                         .unwrap_or(&0) as i64,
                 );

beacon_node/lighthouse_network/src/peer_manager/peerdb/peer_info.rs

@@ -122,6 +122,24 @@ impl<E: EthSpec> PeerInfo<E> {
         self.connection_direction.as_ref()
     }
 
+    /// Returns true if this is an incoming ipv4 connection.
+    pub fn is_incoming_ipv4_connection(&self) -> bool {
+        self.seen_multiaddrs.iter().any(|multiaddr| {
+            multiaddr
+                .iter()
+                .any(|protocol| matches!(protocol, libp2p::core::multiaddr::Protocol::Ip4(_)))
+        })
+    }
+
+    /// Returns true if this is an incoming ipv6 connection.
+    pub fn is_incoming_ipv6_connection(&self) -> bool {
+        self.seen_multiaddrs.iter().any(|multiaddr| {
+            multiaddr
+                .iter()
+                .any(|protocol| matches!(protocol, libp2p::core::multiaddr::Protocol::Ip6(_)))
+        })
+    }
+
     /// Returns the sync status of the peer.
     pub fn sync_status(&self) -> &SyncStatus {
         &self.sync_status