upgrade to libp2p 0.52 (#4431)

## Issue Addressed

Upgrade libp2p to v0.52

## Proposed Changes
- **Workflows**: remove installation of `protoc`
- **Book**: remove installation of `protoc`
- **`Dockerfile`s and `cross`**: remove custom base `Dockerfile` for cross since it's no longer needed. Remove `protoc` from remaining `Dockerfiles`s
- **Upgrade `discv5` to `v0.3.1`:** we have some cool stuff in there: no longer needs `protoc` and faster ip updates on cold start
- **Upgrade `prometheus` to `0.21.0`**, now it no longer needs encoding checks
- **things that look like refactors:** bunch of api types were renamed and need to be accessed in a different (clearer) way
- **Lighthouse network**
	- connection limits is now a behaviour
	- banned peers no longer exist on the swarm level, but at the behaviour level
	- `connection_event_buffer_size` now is handled per connection with a buffer size of 4
	- `mplex` is deprecated and was removed
	- rpc handler now logs the peer to which it belongs

## Additional Info

Tried to keep as much behaviour unchanged as possible. However, there is a great deal of improvements we can do _after_ this upgrade:
- Smart connection limits: Connection limits have been checked only based on numbers, we can now use information about the incoming peer to decide if we want it
- More powerful peer management: Dial attempts from other behaviours can be rejected early
- Incoming connections can be rejected early
- Banning can be returned exclusively to the peer management: We should not get connections to banned peers anymore making use of this
- TCP Nat updates: We might be able to take advantage of confirmed external addresses to check out tcp ports/ips


Co-authored-by: Age Manning <Age@AgeManning.com>
Co-authored-by: Akihito Nakano <sora.akatsuki@gmail.com>

beacon_node/lighthouse_network/src/discovery/mod.rs

@@ -16,19 +16,20 @@ pub use enr::{
     Eth2Enr,
 };
 pub use enr_ext::{peer_id_to_node_id, CombinedKeyExt, EnrExt};
-pub use libp2p::core::identity::{Keypair, PublicKey};
+pub use libp2p::identity::{Keypair, PublicKey};
 
 use enr::{ATTESTATION_BITFIELD_ENR_KEY, ETH2_ENR_KEY, SYNC_COMMITTEE_BITFIELD_ENR_KEY};
 use futures::prelude::*;
 use futures::stream::FuturesUnordered;
 use libp2p::multiaddr::Protocol;
 use libp2p::swarm::behaviour::{DialFailure, FromSwarm};
-use libp2p::swarm::AddressScore;
+use libp2p::swarm::THandlerInEvent;
 pub use libp2p::{
-    core::{connection::ConnectionId, ConnectedPoint, Multiaddr, PeerId},
+    core::{ConnectedPoint, Multiaddr},
+    identity::PeerId,
     swarm::{
-        dummy::ConnectionHandler, DialError, NetworkBehaviour, NetworkBehaviourAction as NBAction,
-        NotifyHandler, PollParameters, SubstreamProtocol,
+        dummy::ConnectionHandler, ConnectionId, DialError, NetworkBehaviour, NotifyHandler,
+        PollParameters, SubstreamProtocol, ToSwarm,
     },
 };
 use lru::LruCache;
@@ -191,7 +192,7 @@ pub struct Discovery<TSpec: EthSpec> {
 impl<TSpec: EthSpec> Discovery<TSpec> {
     /// NOTE: Creating discovery requires running within a tokio execution environment.
     pub async fn new(
-        local_key: &Keypair,
+        local_key: Keypair,
         config: &NetworkConfig,
         network_globals: Arc<NetworkGlobals<TSpec>>,
         log: &slog::Logger,
@@ -925,22 +926,51 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
 impl<TSpec: EthSpec> NetworkBehaviour for Discovery<TSpec> {
     // Discovery is not a real NetworkBehaviour...
     type ConnectionHandler = ConnectionHandler;
-    type OutEvent = DiscoveredPeers;
+    type ToSwarm = DiscoveredPeers;
 
-    fn new_handler(&mut self) -> Self::ConnectionHandler {
-        ConnectionHandler
+    fn handle_established_inbound_connection(
+        &mut self,
+        _connection_id: ConnectionId,
+        _peer: PeerId,
+        _local_addr: &Multiaddr,
+        _remote_addr: &Multiaddr,
+    ) -> Result<libp2p::swarm::THandler<Self>, libp2p::swarm::ConnectionDenied> {
+        // TODO: we might want to check discovery's banned ips here in the future.
+        Ok(ConnectionHandler)
     }
 
-    // Handles the libp2p request to obtain multiaddrs for peer_id's in order to dial them.
-    fn addresses_of_peer(&mut self, peer_id: &PeerId) -> Vec<Multiaddr> {
-        if let Some(enr) = self.enr_of_peer(peer_id) {
+    fn handle_established_outbound_connection(
+        &mut self,
+        _connection_id: ConnectionId,
+        _peer: PeerId,
+        _addr: &Multiaddr,
+        _role_override: libp2p::core::Endpoint,
+    ) -> Result<libp2p::swarm::THandler<Self>, libp2p::swarm::ConnectionDenied> {
+        Ok(ConnectionHandler)
+    }
+
+    fn on_connection_handler_event(
+        &mut self,
+        _peer_id: PeerId,
+        _connection_id: ConnectionId,
+        _event: void::Void,
+    ) {
+    }
+
+    fn handle_pending_outbound_connection(
+        &mut self,
+        _connection_id: ConnectionId,
+        maybe_peer: Option<PeerId>,
+        _addresses: &[Multiaddr],
+        _effective_role: libp2p::core::Endpoint,
+    ) -> Result<Vec<Multiaddr>, libp2p::swarm::ConnectionDenied> {
+        if let Some(enr) = maybe_peer.and_then(|peer_id| self.enr_of_peer(&peer_id)) {
             // ENR's may have multiple Multiaddrs. The multi-addr associated with the UDP
             // port is removed, which is assumed to be associated with the discv5 protocol (and
             // therefore irrelevant for other libp2p components).
-            enr.multiaddr_tcp()
+            Ok(enr.multiaddr_tcp())
         } else {
-            // PeerId is not known
-            Vec::new()
+            Ok(vec![])
         }
     }
 
@@ -949,7 +979,7 @@ impl<TSpec: EthSpec> NetworkBehaviour for Discovery<TSpec> {
         &mut self,
         cx: &mut Context,
         _: &mut impl PollParameters,
-    ) -> Poll<NBAction<Self::OutEvent, Self::ConnectionHandler>> {
+    ) -> Poll<ToSwarm<Self::ToSwarm, THandlerInEvent<Self>>> {
         if !self.started {
             return Poll::Pending;
         }
@@ -960,7 +990,7 @@ impl<TSpec: EthSpec> NetworkBehaviour for Discovery<TSpec> {
         // Drive the queries and return any results from completed queries
         if let Some(peers) = self.poll_queries(cx) {
             // return the result to the peer manager
-            return Poll::Ready(NBAction::GenerateEvent(DiscoveredPeers { peers }));
+            return Poll::Ready(ToSwarm::GenerateEvent(DiscoveredPeers { peers }));
         }
 
         // Process the server event stream
@@ -1034,10 +1064,7 @@ impl<TSpec: EthSpec> NetworkBehaviour for Discovery<TSpec> {
                             if let Some(address) = addr {
                                 // NOTE: This doesn't actually track the external TCP port. More sophisticated NAT handling
                                 // should handle this.
-                                return Poll::Ready(NBAction::ReportObservedAddr {
-                                    address,
-                                    score: AddressScore::Finite(1),
-                                });
+                                return Poll::Ready(ToSwarm::NewExternalAddrCandidate(address));
                             }
                         }
                         Discv5Event::EnrAdded { .. }
@@ -1065,8 +1092,9 @@ impl<TSpec: EthSpec> NetworkBehaviour for Discovery<TSpec> {
             | FromSwarm::ExpiredListenAddr(_)
             | FromSwarm::ListenerError(_)
             | FromSwarm::ListenerClosed(_)
-            | FromSwarm::NewExternalAddr(_)
-            | FromSwarm::ExpiredExternalAddr(_) => {
+            | FromSwarm::NewExternalAddrCandidate(_)
+            | FromSwarm::ExternalAddrExpired(_)
+            | FromSwarm::ExternalAddrConfirmed(_) => {
                 // Ignore events not relevant to discovery
             }
         }
@@ -1077,10 +1105,8 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
     fn on_dial_failure(&mut self, peer_id: Option<PeerId>, error: &DialError) {
         if let Some(peer_id) = peer_id {
             match error {
-                DialError::Banned
-                | DialError::LocalPeerId
-                | DialError::InvalidPeerId(_)
-                | DialError::ConnectionIo(_)
+                DialError::LocalPeerId { .. }
+                | DialError::Denied { .. }
                 | DialError::NoAddresses
                 | DialError::Transport(_)
                 | DialError::WrongPeerId { .. } => {
@@ -1088,9 +1114,7 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
                     debug!(self.log, "Marking peer disconnected in DHT"; "peer_id" => %peer_id);
                     self.disconnect_peer(&peer_id);
                 }
-                DialError::ConnectionLimit(_)
-                | DialError::DialPeerConditionFalse(_)
-                | DialError::Aborted => {}
+                DialError::DialPeerConditionFalse(_) | DialError::Aborted => {}
             }
         }
     }
@@ -1139,8 +1163,8 @@ mod tests {
             false,
             &log,
         );
-        let keypair = Keypair::Secp256k1(keypair);
-        Discovery::new(&keypair, &config, Arc::new(globals), &log)
+        let keypair = keypair.into();
+        Discovery::new(keypair, &config, Arc::new(globals), &log)
             .await
             .unwrap()
     }