feat(net): enforce trusted_nodes_only setting (#660)

* Add PeerKind and enforce trusted_only setting

* Don't remove trusted peer on graceful close

* Don't remove trusted nodes on PeerCommand::Remove

* Rename PeerKind::NonTrusted to Basic

* Move PeerKind::is_trusted to Peer impl

* Add trusted peer prioritization

crates/net/network/src/peers/manager.rs

@@ -93,6 +93,8 @@ pub(crate) struct PeersManager {
     /// How long peers to which we could not connect for non-fatal reasons, e.g.
     /// [`DisconnectReason::TooManyPeers`], are put in time out.
     backoff_duration: Duration,
+    /// If non-trusted peers should be connected to
+    connect_trusted_nodes_only: bool,
 }
 
 impl PeersManager {
@@ -106,6 +108,7 @@ impl PeersManager {
             ban_duration,
             backoff_duration,
             trusted_nodes,
+            connect_trusted_nodes_only,
             ..
         } = config;
         let (manager_tx, handle_rx) = mpsc::unbounded_channel();
@@ -117,7 +120,7 @@ impl PeersManager {
         let mut peers = HashMap::with_capacity(trusted_nodes.len());
 
         for NodeRecord { address, tcp_port, udp_port: _, id } in trusted_nodes {
-            peers.entry(id).or_insert_with(|| Peer::new(SocketAddr::from((address, tcp_port))));
+            peers.entry(id).or_insert_with(|| Peer::trusted(SocketAddr::from((address, tcp_port))));
         }
 
         Self {
@@ -135,6 +138,7 @@ impl PeersManager {
             ban_list,
             ban_duration,
             backoff_duration,
+            connect_trusted_nodes_only,
         }
     }
 
@@ -296,7 +300,7 @@ impl PeersManager {
             Entry::Occupied(mut entry) => {
                 self.connection_info.decr_state(entry.get().state);
 
-                if entry.get().remove_after_disconnect {
+                if entry.get().remove_after_disconnect && !entry.get().is_trusted() {
                     // this peer should be removed from the set
                     entry.remove();
                     self.queued_actions.push_back(PeerAction::PeerRemoved(peer_id));
@@ -424,24 +428,28 @@ impl PeersManager {
 
     /// Removes the tracked node from the set.
     pub(crate) fn remove_discovered_node(&mut self, peer_id: PeerId) {
-        if let Some(mut peer) = self.peers.remove(&peer_id) {
-            trace!(target : "net::peers",  ?peer_id, "remove discovered node");
-            self.queued_actions.push_back(PeerAction::PeerRemoved(peer_id));
+        let Entry::Occupied(entry) = self.peers.entry(peer_id) else { return };
+        if entry.get().is_trusted() {
+            return
+        }
+        let mut peer = entry.remove();
 
-            if peer.state.is_connected() {
-                debug!(target : "net::peers",  ?peer_id, "disconnecting on remove from discovery");
-                // we terminate the active session here, but only remove the peer after the session
-                // was disconnected, this prevents the case where the session is scheduled for
-                // disconnect but the node is immediately rediscovered, See also
-                // [`Self::on_disconnected()`]
-                peer.remove_after_disconnect = true;
-                peer.state.disconnect();
-                self.peers.insert(peer_id, peer);
-                self.queued_actions.push_back(PeerAction::Disconnect {
-                    peer_id,
-                    reason: Some(DisconnectReason::DisconnectRequested),
-                })
-            }
+        trace!(target : "net::peers",  ?peer_id, "remove discovered node");
+        self.queued_actions.push_back(PeerAction::PeerRemoved(peer_id));
+
+        if peer.state.is_connected() {
+            debug!(target : "net::peers",  ?peer_id, "disconnecting on remove from discovery");
+            // we terminate the active session here, but only remove the peer after the session
+            // was disconnected, this prevents the case where the session is scheduled for
+            // disconnect but the node is immediately rediscovered, See also
+            // [`Self::on_disconnected()`]
+            peer.remove_after_disconnect = true;
+            peer.state.disconnect();
+            self.peers.insert(peer_id, peer);
+            self.queued_actions.push_back(PeerAction::Disconnect {
+                peer_id,
+                reason: Some(DisconnectReason::DisconnectRequested),
+            })
         }
     }
 
@@ -451,12 +459,23 @@ impl PeersManager {
     ///
     /// Returns `None` if no peer is available.
     fn best_unconnected(&mut self) -> Option<(PeerId, &mut Peer)> {
-        let mut unconnected = self.peers.iter_mut().filter(|(_, peer)| peer.state.is_unconnected());
+        let mut unconnected = self.peers.iter_mut().filter(|(_, peer)| {
+            peer.state.is_unconnected() &&
+                !peer.is_banned() &&
+                (!self.connect_trusted_nodes_only || peer.is_trusted())
+        });
 
         // keep track of the best peer, if there's one
         let mut best_peer = unconnected.next()?;
 
+        if best_peer.1.is_trusted() {
+            return Some((*best_peer.0, best_peer.1))
+        }
+
         for maybe_better in unconnected {
+            if maybe_better.1.is_trusted() {
+                return Some((*maybe_better.0, maybe_better.1))
+            }
             match (maybe_better.1.fork_id.as_ref(), best_peer.1.fork_id.as_ref()) {
                 (Some(_), Some(_)) | (None, None) => {
                     if maybe_better.1.reputation > best_peer.1.reputation {
@@ -464,9 +483,7 @@ impl PeersManager {
                     }
                 }
                 (Some(_), None) => {
-                    if !maybe_better.1.is_banned() {
-                        best_peer = maybe_better;
-                    }
+                    best_peer = maybe_better;
                 }
                 _ => {}
             }
@@ -630,6 +647,8 @@ pub struct Peer {
     fork_id: Option<ForkId>,
     /// Whether the entry should be removed after an existing session was terminated.
     remove_after_disconnect: bool,
+    /// The kind of peer
+    kind: PeerKind,
 }
 
 // === impl Peer ===
@@ -639,6 +658,10 @@ impl Peer {
         Self::with_state(addr, Default::default())
     }
 
+    fn trusted(addr: SocketAddr) -> Self {
+        Self { kind: PeerKind::Trusted, ..Self::new(addr) }
+    }
+
     fn with_state(addr: SocketAddr, state: PeerConnectionState) -> Self {
         Self {
             addr,
@@ -646,6 +669,7 @@ impl Peer {
             reputation: DEFAULT_REPUTATION,
             fork_id: None,
             remove_after_disconnect: false,
+            kind: Default::default(),
         }
     }
 
@@ -684,6 +708,12 @@ impl Peer {
     fn unban(&mut self) {
         self.reputation = DEFAULT_REPUTATION
     }
+
+    /// Returns whether this peer is trusted
+    #[inline]
+    fn is_trusted(&self) -> bool {
+        matches!(self.kind, PeerKind::Trusted)
+    }
 }
 
 /// Outcomes when a reputation change is applied to a peer
@@ -740,6 +770,16 @@ impl PeerConnectionState {
     }
 }
 
+/// Represents the kind of peer
+#[derive(Debug, Clone, Copy, Default, Eq, PartialEq)]
+enum PeerKind {
+    /// Basic peer kind.
+    #[default]
+    Basic,
+    /// Trusted peer.
+    Trusted,
+}
+
 /// Commands the [`PeersManager`] listens for.
 pub(crate) enum PeerCommand {
     /// Command for manually add