Explicit peers (#5333)

* Merge branch 'unstable' into feature/explicit-peers

* Merge latest unstable

* refactor: remove explicit-peers flag, mark trusted peers as explicit instead

* feat(beacon_node): add explicit peers to GossipSub, mark as trusted

* feat(beacon_node): add explicit peers cli + config

Author: Jonas Bostoen

beacon_node/lighthouse_network/src/config.rs

@@ -101,7 +101,7 @@ pub struct Config {
     /// List of libp2p nodes to initially connect to.
     pub libp2p_nodes: Vec<Multiaddr>,
 
-    /// List of trusted libp2p nodes which are not scored.
+    /// List of trusted libp2p nodes which are not scored and marked as explicit.
     pub trusted_peers: Vec<PeerIdSerialized>,
 
     /// Disables peer scoring altogether.

beacon_node/lighthouse_network/src/service/mod.rs

@@ -144,6 +144,14 @@ impl<AppReqId: ReqId, TSpec: EthSpec> Network<AppReqId, TSpec> {
         // initialise the node's ID
         let local_keypair = utils::load_private_key(&config, &log);
 
+        // Trusted peers will also be marked as explicit in GossipSub.
+        // Cfr. https://github.com/libp2p/specs/blob/master/pubsub/gossipsub/gossipsub-v1.1.md#explicit-peering-agreements
+        let trusted_peers: Vec<PeerId> = config
+            .trusted_peers
+            .iter()
+            .map(|x| PeerId::from(x.clone()))
+            .collect();
+
         // set up a collection of variables accessible outside of the network crate
         let network_globals = {
             // Create an ENR or load from disk if appropriate
@@ -158,11 +166,7 @@ impl<AppReqId: ReqId, TSpec: EthSpec> Network<AppReqId, TSpec> {
             let globals = NetworkGlobals::new(
                 enr,
                 meta_data,
-                config
-                    .trusted_peers
-                    .iter()
-                    .map(|x| PeerId::from(x.clone()))
-                    .collect(),
+                trusted_peers,
                 config.disable_peer_scoring,
                 &log,
             );
@@ -275,6 +279,11 @@ impl<AppReqId: ReqId, TSpec: EthSpec> Network<AppReqId, TSpec> {
                 .with_peer_score(params, thresholds)
                 .expect("Valid score params and thresholds");
 
+            // Mark trusted peers as explicit.
+            for explicit_peer in config.trusted_peers.iter() {
+                gossipsub.add_explicit_peer(&PeerId::from(explicit_peer.clone()));
+            }
+
             // If we are using metrics, then register which topics we want to make sure to keep
             // track of
             if ctx.libp2p_registry.is_some() {