Improve transport connection errors (#4540)

## Issue Addressed

#4538 

## Proposed Changes

add newtype wrapper around DialError that extracts error messages and logs them in a more readable format

## Additional Info

I was able to test Transport Dial Errors in the situation where a libp2p instance attempts to ping a nonexistent peer. That error message should look something like

`A transport level error has ocurred: Connection refused (os error 61)`

AgeManning mentioned we should try fetching only the most inner error (in situations where theres a nested error). I took a stab at implementing that

For non transport DialErrors, I wrote out the error messages explicitly (as per the docs). Could potentially clean things up here if thats not necessary


Co-authored-by: Age Manning <Age@AgeManning.com>

beacon_node/lighthouse_network/src/discovery/mod.rs

@@ -7,9 +7,9 @@ pub(crate) mod enr;
 pub mod enr_ext;
 
 // Allow external use of the lighthouse ENR builder
-use crate::metrics;
 use crate::service::TARGET_SUBNET_PEERS;
 use crate::{error, Enr, NetworkConfig, NetworkGlobals, Subnet, SubnetDiscovery};
+use crate::{metrics, ClearDialError};
 use discv5::{enr::NodeId, Discv5, Discv5Event};
 pub use enr::{
     build_enr, create_enr_builder_from_config, load_enr_from_disk, use_or_load_enr, CombinedKey,
@@ -1111,7 +1111,7 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
                 | DialError::Transport(_)
                 | DialError::WrongPeerId { .. } => {
                     // set peer as disconnected in discovery DHT
-                    debug!(self.log, "Marking peer disconnected in DHT"; "peer_id" => %peer_id);
+                    debug!(self.log, "Marking peer disconnected in DHT"; "peer_id" => %peer_id, "error" => %ClearDialError(error));
                     self.disconnect_peer(&peer_id);
                 }
                 DialError::DialPeerConditionFalse(_) | DialError::Aborted => {}

beacon_node/lighthouse_network/src/lib.rs

@@ -17,6 +17,7 @@ pub mod rpc;
 pub mod types;
 
 pub use config::gossip_max_size;
+use libp2p::swarm::DialError;
 pub use listen_addr::*;
 
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
@@ -63,6 +64,46 @@ impl<'de> Deserialize<'de> for PeerIdSerialized {
     }
 }
 
+// A wrapper struct that prints a dial error nicely.
+struct ClearDialError<'a>(&'a DialError);
+
+impl<'a> ClearDialError<'a> {
+    fn most_inner_error(err: &(dyn std::error::Error)) -> &(dyn std::error::Error) {
+        let mut current = err;
+        while let Some(source) = current.source() {
+            current = source;
+        }
+        current
+    }
+}
+
+impl<'a> std::fmt::Display for ClearDialError<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        match &self.0 {
+            DialError::Transport(errors) => {
+                for (_, transport_error) in errors {
+                    match transport_error {
+                        libp2p::TransportError::MultiaddrNotSupported(multiaddr_error) => {
+                            write!(f, "Multiaddr not supported: {multiaddr_error}")?;
+                        }
+                        libp2p::TransportError::Other(other_error) => {
+                            let inner_error = ClearDialError::most_inner_error(other_error);
+                            write!(f, "Transport error: {inner_error}")?;
+                        }
+                    }
+                }
+                Ok(())
+            }
+            DialError::LocalPeerId { .. } => write!(f, "The peer being dialed is the local peer."),
+            DialError::NoAddresses => write!(f, "No addresses for the peer to dial."),
+            DialError::DialPeerConditionFalse(_) => write!(f, "PeerCondition evaluation failed."),
+            DialError::Aborted => write!(f, "Connection aborted."),
+            DialError::WrongPeerId { .. } => write!(f, "Wrong peer id."),
+            DialError::Denied { cause } => write!(f, "Connection denied: {:?}", cause),
+        }
+    }
+}
+
 pub use crate::types::{
     error, Enr, EnrSyncCommitteeBitfield, GossipTopic, NetworkGlobals, PubsubMessage, Subnet,
     SubnetDiscovery,

beacon_node/lighthouse_network/src/peer_manager/network_behaviour.rs

@@ -12,9 +12,9 @@ use libp2p::swarm::{ConnectionId, NetworkBehaviour, PollParameters, ToSwarm};
 use slog::{debug, error};
 use types::EthSpec;
 
-use crate::metrics;
 use crate::rpc::GoodbyeReason;
 use crate::types::SyncState;
+use crate::{metrics, ClearDialError};
 
 use super::peerdb::BanResult;
 use super::{ConnectingType, PeerManager, PeerManagerEvent, ReportSource};
@@ -132,7 +132,7 @@ impl<TSpec: EthSpec> NetworkBehaviour for PeerManager<TSpec> {
                 error,
                 connection_id: _,
             }) => {
-                debug!(self.log, "Failed to dial peer"; "peer_id"=> ?peer_id, "error" => %error);
+                debug!(self.log, "Failed to dial peer"; "peer_id"=> ?peer_id, "error" => %ClearDialError(error));
                 self.on_dial_failure(peer_id);
             }
             FromSwarm::ExternalAddrConfirmed(_) => {