Rename eth2_libp2p to lighthouse_network (#2702)

## Description

The `eth2_libp2p` crate was originally named and designed to incorporate a simple libp2p integration into lighthouse. Since its origins the crates purpose has expanded dramatically. It now houses a lot more sophistication that is specific to lighthouse and no longer just a libp2p integration. 

As of this writing it currently houses the following high-level lighthouse-specific logic:
- Lighthouse's implementation of the eth2 RPC protocol and specific encodings/decodings
- Integration and handling of ENRs with respect to libp2p and eth2
- Lighthouse's discovery logic, its integration with discv5 and logic about searching and handling peers. 
- Lighthouse's peer manager - This is a large module handling various aspects of Lighthouse's network, such as peer scoring, handling pings and metadata, connection maintenance and recording, etc.
- Lighthouse's peer database - This is a collection of information stored for each individual peer which is specific to lighthouse. We store connection state, sync state, last seen ips and scores etc. The data stored for each peer is designed for various elements of the lighthouse code base such as syncing and the http api.
- Gossipsub scoring - This stores a collection of gossipsub 1.1 scoring mechanisms that are continuously analyssed and updated based on the ethereum 2 networks and how Lighthouse performs on these networks.
- Lighthouse specific types for managing gossipsub topics, sync status and ENR fields
- Lighthouse's network HTTP API metrics - A collection of metrics for lighthouse network monitoring
- Lighthouse's custom configuration of all networking protocols, RPC, gossipsub, discovery, identify and libp2p. 

Therefore it makes sense to rename the crate to be more akin to its current purposes, simply that it manages the majority of Lighthouse's network stack. This PR renames this crate to `lighthouse_network`

Co-authored-by: Paul Hauner <paul@paulhauner.com>

beacon_node/lighthouse_network/src/discovery/enr.rs

@@ -0,0 +1,236 @@
+//! Helper functions and an extension trait for Ethereum 2 ENRs.
+
+pub use discv5::enr::{self, CombinedKey, EnrBuilder};
+
+use super::enr_ext::CombinedKeyExt;
+use super::ENR_FILENAME;
+use crate::types::{Enr, EnrAttestationBitfield, EnrSyncCommitteeBitfield};
+use crate::NetworkConfig;
+use discv5::enr::EnrKey;
+use libp2p::core::identity::Keypair;
+use slog::{debug, warn};
+use ssz::{Decode, Encode};
+use ssz_types::BitVector;
+use std::fs::File;
+use std::io::prelude::*;
+use std::path::Path;
+use std::str::FromStr;
+use types::{EnrForkId, EthSpec};
+
+/// The ENR field specifying the fork id.
+pub const ETH2_ENR_KEY: &str = "eth2";
+/// The ENR field specifying the attestation subnet bitfield.
+pub const ATTESTATION_BITFIELD_ENR_KEY: &str = "attnets";
+/// The ENR field specifying the sync committee subnet bitfield.
+pub const SYNC_COMMITTEE_BITFIELD_ENR_KEY: &str = "syncnets";
+
+/// Extension trait for ENR's within Eth2.
+pub trait Eth2Enr {
+    /// The attestation subnet bitfield associated with the ENR.
+    fn attestation_bitfield<TSpec: EthSpec>(
+        &self,
+    ) -> Result<EnrAttestationBitfield<TSpec>, &'static str>;
+
+    /// The sync committee subnet bitfield associated with the ENR.
+    fn sync_committee_bitfield<TSpec: EthSpec>(
+        &self,
+    ) -> Result<EnrSyncCommitteeBitfield<TSpec>, &'static str>;
+
+    fn eth2(&self) -> Result<EnrForkId, &'static str>;
+}
+
+impl Eth2Enr for Enr {
+    fn attestation_bitfield<TSpec: EthSpec>(
+        &self,
+    ) -> Result<EnrAttestationBitfield<TSpec>, &'static str> {
+        let bitfield_bytes = self
+            .get(ATTESTATION_BITFIELD_ENR_KEY)
+            .ok_or("ENR attestation bitfield non-existent")?;
+
+        BitVector::<TSpec::SubnetBitfieldLength>::from_ssz_bytes(bitfield_bytes)
+            .map_err(|_| "Could not decode the ENR attnets bitfield")
+    }
+
+    fn sync_committee_bitfield<TSpec: EthSpec>(
+        &self,
+    ) -> Result<EnrSyncCommitteeBitfield<TSpec>, &'static str> {
+        let bitfield_bytes = self
+            .get(SYNC_COMMITTEE_BITFIELD_ENR_KEY)
+            .ok_or("ENR sync committee bitfield non-existent")?;
+
+        BitVector::<TSpec::SyncCommitteeSubnetCount>::from_ssz_bytes(bitfield_bytes)
+            .map_err(|_| "Could not decode the ENR syncnets bitfield")
+    }
+
+    fn eth2(&self) -> Result<EnrForkId, &'static str> {
+        let eth2_bytes = self.get(ETH2_ENR_KEY).ok_or("ENR has no eth2 field")?;
+
+        EnrForkId::from_ssz_bytes(eth2_bytes).map_err(|_| "Could not decode EnrForkId")
+    }
+}
+
+/// Either use the given ENR or load an ENR from file if it exists and matches the current NodeId
+/// and sequence number.
+/// If an ENR exists, with the same NodeId, this function checks to see if the loaded ENR from
+/// disk is suitable to use, otherwise we increment the given ENR's sequence number.
+pub fn use_or_load_enr(
+    enr_key: &CombinedKey,
+    local_enr: &mut Enr,
+    config: &NetworkConfig,
+    log: &slog::Logger,
+) -> Result<(), String> {
+    let enr_f = config.network_dir.join(ENR_FILENAME);
+    if let Ok(mut enr_file) = File::open(enr_f.clone()) {
+        let mut enr_string = String::new();
+        match enr_file.read_to_string(&mut enr_string) {
+            Err(_) => debug!(log, "Could not read ENR from file"),
+            Ok(_) => {
+                match Enr::from_str(&enr_string) {
+                    Ok(disk_enr) => {
+                        // if the same node id, then we may need to update our sequence number
+                        if local_enr.node_id() == disk_enr.node_id() {
+                            if compare_enr(local_enr, &disk_enr) {
+                                debug!(log, "ENR loaded from disk"; "file" => ?enr_f);
+                                // the stored ENR has the same configuration, use it
+                                *local_enr = disk_enr;
+                                return Ok(());
+                            }
+
+                            // same node id, different configuration - update the sequence number
+                            // Note: local_enr is generated with default(0) attnets value,
+                            // so a non default value in persisted enr will also update sequence number.
+                            let new_seq_no = disk_enr.seq().checked_add(1).ok_or("ENR sequence number on file is too large. Remove it to generate a new NodeId")?;
+                            local_enr.set_seq(new_seq_no, enr_key).map_err(|e| {
+                                format!("Could not update ENR sequence number: {:?}", e)
+                            })?;
+                            debug!(log, "ENR sequence number increased"; "seq" =>  new_seq_no);
+                        }
+                    }
+                    Err(e) => {
+                        warn!(log, "ENR from file could not be decoded"; "error" => ?e);
+                    }
+                }
+            }
+        }
+    }
+
+    save_enr_to_disk(&config.network_dir, local_enr, log);
+
+    Ok(())
+}
+
+/// Loads an ENR from file if it exists and matches the current NodeId and sequence number. If none
+/// exists, generates a new one.
+///
+/// If an ENR exists, with the same NodeId, this function checks to see if the loaded ENR from
+/// disk is suitable to use, otherwise we increment our newly generated ENR's sequence number.
+pub fn build_or_load_enr<T: EthSpec>(
+    local_key: Keypair,
+    config: &NetworkConfig,
+    enr_fork_id: EnrForkId,
+    log: &slog::Logger,
+) -> Result<Enr, String> {
+    // Build the local ENR.
+    // Note: Discovery should update the ENR record's IP to the external IP as seen by the
+    // majority of our peers, if the CLI doesn't expressly forbid it.
+    let enr_key = CombinedKey::from_libp2p(&local_key)?;
+    let mut local_enr = build_enr::<T>(&enr_key, config, enr_fork_id)?;
+
+    use_or_load_enr(&enr_key, &mut local_enr, config, log)?;
+    Ok(local_enr)
+}
+
+pub fn create_enr_builder_from_config<T: EnrKey>(
+    config: &NetworkConfig,
+    enable_tcp: bool,
+) -> EnrBuilder<T> {
+    let mut builder = EnrBuilder::new("v4");
+    if let Some(enr_address) = config.enr_address {
+        builder.ip(enr_address);
+    }
+    if let Some(udp_port) = config.enr_udp_port {
+        builder.udp(udp_port);
+    }
+    // we always give it our listening tcp port
+    if enable_tcp {
+        let tcp_port = config.enr_tcp_port.unwrap_or(config.libp2p_port);
+        builder.tcp(tcp_port);
+    }
+    builder
+}
+
+/// Builds a lighthouse ENR given a `NetworkConfig`.
+pub fn build_enr<T: EthSpec>(
+    enr_key: &CombinedKey,
+    config: &NetworkConfig,
+    enr_fork_id: EnrForkId,
+) -> Result<Enr, String> {
+    let mut builder = create_enr_builder_from_config(config, true);
+
+    // set the `eth2` field on our ENR
+    builder.add_value(ETH2_ENR_KEY, &enr_fork_id.as_ssz_bytes());
+
+    // set the "attnets" field on our ENR
+    let bitfield = BitVector::<T::SubnetBitfieldLength>::new();
+
+    builder.add_value(ATTESTATION_BITFIELD_ENR_KEY, &bitfield.as_ssz_bytes());
+
+    // set the "syncnets" field on our ENR
+    let bitfield = BitVector::<T::SyncCommitteeSubnetCount>::new();
+
+    builder.add_value(SYNC_COMMITTEE_BITFIELD_ENR_KEY, &bitfield.as_ssz_bytes());
+
+    builder
+        .build(enr_key)
+        .map_err(|e| format!("Could not build Local ENR: {:?}", e))
+}
+
+/// Defines the conditions under which we use the locally built ENR or the one stored on disk.
+/// If this function returns true, we use the `disk_enr`.
+fn compare_enr(local_enr: &Enr, disk_enr: &Enr) -> bool {
+    // take preference over disk_enr address if one is not specified
+    (local_enr.ip().is_none() || local_enr.ip() == disk_enr.ip())
+        // tcp ports must match
+        && local_enr.tcp() == disk_enr.tcp()
+        // must match on the same fork
+        && local_enr.get(ETH2_ENR_KEY) == disk_enr.get(ETH2_ENR_KEY)
+        // take preference over disk udp port if one is not specified
+        && (local_enr.udp().is_none() || local_enr.udp() == disk_enr.udp())
+        // we need the ATTESTATION_BITFIELD_ENR_KEY and SYNC_COMMITTEE_BITFIELD_ENR_KEY key to match, 
+        // otherwise we use a new ENR. This will likely only be true for non-validating nodes
+        && local_enr.get(ATTESTATION_BITFIELD_ENR_KEY) == disk_enr.get(ATTESTATION_BITFIELD_ENR_KEY)
+        && local_enr.get(SYNC_COMMITTEE_BITFIELD_ENR_KEY) == disk_enr.get(SYNC_COMMITTEE_BITFIELD_ENR_KEY)
+}
+
+/// Loads enr from the given directory
+pub fn load_enr_from_disk(dir: &Path) -> Result<Enr, String> {
+    let enr_f = dir.join(ENR_FILENAME);
+    let mut enr_file =
+        File::open(enr_f).map_err(|e| format!("Failed to open enr file: {:?}", e))?;
+    let mut enr_string = String::new();
+    match enr_file.read_to_string(&mut enr_string) {
+        Err(_) => Err("Could not read ENR from file".to_string()),
+        Ok(_) => match Enr::from_str(&enr_string) {
+            Ok(disk_enr) => Ok(disk_enr),
+            Err(e) => Err(format!("ENR from file could not be decoded: {:?}", e)),
+        },
+    }
+}
+
+/// Saves an ENR to disk
+pub fn save_enr_to_disk(dir: &Path, enr: &Enr, log: &slog::Logger) {
+    let _ = std::fs::create_dir_all(dir);
+    match File::create(dir.join(Path::new(ENR_FILENAME)))
+        .and_then(|mut f| f.write_all(enr.to_base64().as_bytes()))
+    {
+        Ok(_) => {
+            debug!(log, "ENR written to disk");
+        }
+        Err(e) => {
+            warn!(
+                log,
+                "Could not write ENR to file"; "file" => format!("{:?}{:?}",dir, ENR_FILENAME),  "error" => %e
+            );
+        }
+    }
+}

beacon_node/lighthouse_network/src/discovery/enr_ext.rs

@@ -0,0 +1,314 @@
+//! ENR extension trait to support libp2p integration.
+use crate::{Enr, Multiaddr, PeerId};
+use discv5::enr::{CombinedKey, CombinedPublicKey};
+use libp2p::core::{identity::Keypair, identity::PublicKey, multiaddr::Protocol};
+use tiny_keccak::{Hasher, Keccak};
+
+/// Extend ENR for libp2p types.
+pub trait EnrExt {
+    /// The libp2p `PeerId` for the record.
+    fn peer_id(&self) -> PeerId;
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and either a `tcp` or `udp` key **or** an `ip6` and either a `tcp6` or `udp6`.
+    /// The vector remains empty if these fields are not defined.
+    fn multiaddr(&self) -> Vec<Multiaddr>;
+
+    /// Returns a list of multiaddrs with the `PeerId` prepended.
+    fn multiaddr_p2p(&self) -> Vec<Multiaddr>;
+
+    /// Returns any multiaddrs that contain the TCP protocol with the `PeerId` prepended.
+    fn multiaddr_p2p_tcp(&self) -> Vec<Multiaddr>;
+
+    /// Returns any multiaddrs that contain the UDP protocol with the `PeerId` prepended.
+    fn multiaddr_p2p_udp(&self) -> Vec<Multiaddr>;
+
+    /// Returns any multiaddrs that contain the TCP protocol.
+    fn multiaddr_tcp(&self) -> Vec<Multiaddr>;
+}
+
+/// Extend ENR CombinedPublicKey for libp2p types.
+pub trait CombinedKeyPublicExt {
+    /// Converts the publickey into a peer id, without consuming the key.
+    fn as_peer_id(&self) -> PeerId;
+}
+
+/// Extend ENR CombinedKey for conversion to libp2p keys.
+pub trait CombinedKeyExt {
+    /// Converts a libp2p key into an ENR combined key.
+    fn from_libp2p(key: &libp2p::core::identity::Keypair) -> Result<CombinedKey, &'static str>;
+}
+
+impl EnrExt for Enr {
+    /// The libp2p `PeerId` for the record.
+    fn peer_id(&self) -> PeerId {
+        self.public_key().as_peer_id()
+    }
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and either a `tcp` or `udp` key **or** an `ip6` and either a `tcp6` or `udp6`.
+    /// The vector remains empty if these fields are not defined.
+    fn multiaddr(&self) -> Vec<Multiaddr> {
+        let mut multiaddrs: Vec<Multiaddr> = Vec::new();
+        if let Some(ip) = self.ip() {
+            if let Some(udp) = self.udp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Udp(udp));
+                multiaddrs.push(multiaddr);
+            }
+
+            if let Some(tcp) = self.tcp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Tcp(tcp));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        if let Some(ip6) = self.ip6() {
+            if let Some(udp6) = self.udp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Udp(udp6));
+                multiaddrs.push(multiaddr);
+            }
+
+            if let Some(tcp6) = self.tcp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Tcp(tcp6));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        multiaddrs
+    }
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and either a `tcp` or `udp` key **or** an `ip6` and either a `tcp6` or `udp6`.
+    /// The vector remains empty if these fields are not defined.
+    ///
+    /// This also prepends the `PeerId` into each multiaddr with the `P2p` protocol.
+    fn multiaddr_p2p(&self) -> Vec<Multiaddr> {
+        let peer_id = self.peer_id();
+        let mut multiaddrs: Vec<Multiaddr> = Vec::new();
+        if let Some(ip) = self.ip() {
+            if let Some(udp) = self.udp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Udp(udp));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+
+            if let Some(tcp) = self.tcp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Tcp(tcp));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        if let Some(ip6) = self.ip6() {
+            if let Some(udp6) = self.udp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Udp(udp6));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+
+            if let Some(tcp6) = self.tcp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Tcp(tcp6));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        multiaddrs
+    }
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and a `tcp` key **or** an `ip6` and a `tcp6`.
+    /// The vector remains empty if these fields are not defined.
+    ///
+    /// This also prepends the `PeerId` into each multiaddr with the `P2p` protocol.
+    fn multiaddr_p2p_tcp(&self) -> Vec<Multiaddr> {
+        let peer_id = self.peer_id();
+        let mut multiaddrs: Vec<Multiaddr> = Vec::new();
+        if let Some(ip) = self.ip() {
+            if let Some(tcp) = self.tcp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Tcp(tcp));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        if let Some(ip6) = self.ip6() {
+            if let Some(tcp6) = self.tcp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Tcp(tcp6));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        multiaddrs
+    }
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and a `udp` key **or** an `ip6` and a `udp6`.
+    /// The vector remains empty if these fields are not defined.
+    ///
+    /// This also prepends the `PeerId` into each multiaddr with the `P2p` protocol.
+    fn multiaddr_p2p_udp(&self) -> Vec<Multiaddr> {
+        let peer_id = self.peer_id();
+        let mut multiaddrs: Vec<Multiaddr> = Vec::new();
+        if let Some(ip) = self.ip() {
+            if let Some(udp) = self.udp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Udp(udp));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        if let Some(ip6) = self.ip6() {
+            if let Some(udp6) = self.udp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Udp(udp6));
+                multiaddr.push(Protocol::P2p(peer_id.into()));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        multiaddrs
+    }
+
+    /// Returns a list of multiaddrs if the ENR has an `ip` and either a `tcp` or `udp` key **or** an `ip6` and either a `tcp6` or `udp6`.
+    /// The vector remains empty if these fields are not defined.
+    fn multiaddr_tcp(&self) -> Vec<Multiaddr> {
+        let mut multiaddrs: Vec<Multiaddr> = Vec::new();
+        if let Some(ip) = self.ip() {
+            if let Some(tcp) = self.tcp() {
+                let mut multiaddr: Multiaddr = ip.into();
+                multiaddr.push(Protocol::Tcp(tcp));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        if let Some(ip6) = self.ip6() {
+            if let Some(tcp6) = self.tcp6() {
+                let mut multiaddr: Multiaddr = ip6.into();
+                multiaddr.push(Protocol::Tcp(tcp6));
+                multiaddrs.push(multiaddr);
+            }
+        }
+        multiaddrs
+    }
+}
+
+impl CombinedKeyPublicExt for CombinedPublicKey {
+    /// Converts the publickey into a peer id, without consuming the key.
+    ///
+    /// This is only available with the `libp2p` feature flag.
+    fn as_peer_id(&self) -> PeerId {
+        match self {
+            Self::Secp256k1(pk) => {
+                let pk_bytes = pk.to_bytes();
+                let libp2p_pk = libp2p::core::PublicKey::Secp256k1(
+                    libp2p::core::identity::secp256k1::PublicKey::decode(&pk_bytes)
+                        .expect("valid public key"),
+                );
+                PeerId::from_public_key(&libp2p_pk)
+            }
+            Self::Ed25519(pk) => {
+                let pk_bytes = pk.to_bytes();
+                let libp2p_pk = libp2p::core::PublicKey::Ed25519(
+                    libp2p::core::identity::ed25519::PublicKey::decode(&pk_bytes)
+                        .expect("valid public key"),
+                );
+                PeerId::from_public_key(&libp2p_pk)
+            }
+        }
+    }
+}
+
+impl CombinedKeyExt for CombinedKey {
+    fn from_libp2p(key: &libp2p::core::identity::Keypair) -> Result<CombinedKey, &'static str> {
+        match key {
+            Keypair::Secp256k1(key) => {
+                let secret =
+                    discv5::enr::k256::ecdsa::SigningKey::from_bytes(&key.secret().to_bytes())
+                        .expect("libp2p key must be valid");
+                Ok(CombinedKey::Secp256k1(secret))
+            }
+            Keypair::Ed25519(key) => {
+                let ed_keypair =
+                    discv5::enr::ed25519_dalek::SecretKey::from_bytes(&key.encode()[..32])
+                        .expect("libp2p key must be valid");
+                Ok(CombinedKey::from(ed_keypair))
+            }
+            _ => Err("ENR: Unsupported libp2p key type"),
+        }
+    }
+}
+
+// helper function to convert a peer_id to a node_id. This is only possible for secp256k1/ed25519 libp2p
+// peer_ids
+pub fn peer_id_to_node_id(peer_id: &PeerId) -> Result<discv5::enr::NodeId, String> {
+    // A libp2p peer id byte representation should be 2 length bytes + 4 protobuf bytes + compressed pk bytes
+    // if generated from a PublicKey with Identity multihash.
+    let pk_bytes = &peer_id.to_bytes()[2..];
+
+    match PublicKey::from_protobuf_encoding(pk_bytes).map_err(|e| {
+        format!(
+            " Cannot parse libp2p public key public key from peer id: {}",
+            e
+        )
+    })? {
+        PublicKey::Secp256k1(pk) => {
+            let uncompressed_key_bytes = &pk.encode_uncompressed()[1..];
+            let mut output = [0_u8; 32];
+            let mut hasher = Keccak::v256();
+            hasher.update(uncompressed_key_bytes);
+            hasher.finalize(&mut output);
+            Ok(discv5::enr::NodeId::parse(&output).expect("Must be correct length"))
+        }
+        PublicKey::Ed25519(pk) => {
+            let uncompressed_key_bytes = pk.encode();
+            let mut output = [0_u8; 32];
+            let mut hasher = Keccak::v256();
+            hasher.update(&uncompressed_key_bytes);
+            hasher.finalize(&mut output);
+            Ok(discv5::enr::NodeId::parse(&output).expect("Must be correct length"))
+        }
+        _ => Err("Unsupported public key".into()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_secp256k1_peer_id_conversion() {
+        let sk_hex = "df94a73d528434ce2309abb19c16aedb535322797dbd59c157b1e04095900f48";
+        let sk_bytes = hex::decode(sk_hex).unwrap();
+        let secret_key = discv5::enr::k256::ecdsa::SigningKey::from_bytes(&sk_bytes).unwrap();
+
+        let libp2p_sk = libp2p::identity::secp256k1::SecretKey::from_bytes(sk_bytes).unwrap();
+        let secp256k1_kp: libp2p::identity::secp256k1::Keypair = libp2p_sk.into();
+        let libp2p_kp = Keypair::Secp256k1(secp256k1_kp);
+        let peer_id = libp2p_kp.public().to_peer_id();
+
+        let enr = discv5::enr::EnrBuilder::new("v4")
+            .build(&secret_key)
+            .unwrap();
+        let node_id = peer_id_to_node_id(&peer_id).unwrap();
+
+        assert_eq!(enr.node_id(), node_id);
+    }
+
+    #[test]
+    fn test_ed25519_peer_conversion() {
+        let sk_hex = "4dea8a5072119927e9d243a7d953f2f4bc95b70f110978e2f9bc7a9000e4b261";
+        let sk_bytes = hex::decode(sk_hex).unwrap();
+        let secret = discv5::enr::ed25519_dalek::SecretKey::from_bytes(&sk_bytes).unwrap();
+        let public = discv5::enr::ed25519_dalek::PublicKey::from(&secret);
+        let keypair = discv5::enr::ed25519_dalek::Keypair { secret, public };
+
+        let libp2p_sk = libp2p::identity::ed25519::SecretKey::from_bytes(sk_bytes).unwrap();
+        let ed25519_kp: libp2p::identity::ed25519::Keypair = libp2p_sk.into();
+        let libp2p_kp = Keypair::Ed25519(ed25519_kp);
+        let peer_id = libp2p_kp.public().to_peer_id();
+
+        let enr = discv5::enr::EnrBuilder::new("v4").build(&keypair).unwrap();
+        let node_id = peer_id_to_node_id(&peer_id).unwrap();
+
+        assert_eq!(enr.node_id(), node_id);
+    }
+}

beacon_node/lighthouse_network/src/discovery/subnet_predicate.rs

@@ -0,0 +1,47 @@
+///! The subnet predicate used for searching for a particular subnet.
+use super::*;
+use crate::types::{EnrAttestationBitfield, EnrSyncCommitteeBitfield};
+use slog::trace;
+use std::ops::Deref;
+
+/// Returns the predicate for a given subnet.
+pub fn subnet_predicate<TSpec>(
+    subnets: Vec<Subnet>,
+    log: &slog::Logger,
+) -> impl Fn(&Enr) -> bool + Send
+where
+    TSpec: EthSpec,
+{
+    let log_clone = log.clone();
+
+    move |enr: &Enr| {
+        let attestation_bitfield: EnrAttestationBitfield<TSpec> =
+            match enr.attestation_bitfield::<TSpec>() {
+                Ok(b) => b,
+                Err(_e) => return false,
+            };
+
+        // Pre-fork/fork-boundary enrs may not contain a syncnets field.
+        // Don't return early here
+        let sync_committee_bitfield: Result<EnrSyncCommitteeBitfield<TSpec>, _> =
+            enr.sync_committee_bitfield::<TSpec>();
+
+        let predicate = subnets.iter().any(|subnet| match subnet {
+            Subnet::Attestation(s) => attestation_bitfield
+                .get(*s.deref() as usize)
+                .unwrap_or(false),
+            Subnet::SyncCommittee(s) => sync_committee_bitfield
+                .as_ref()
+                .map_or(false, |b| b.get(*s.deref() as usize).unwrap_or(false)),
+        });
+
+        if !predicate {
+            trace!(
+                log_clone,
+                "Peer found but not on any of the desired subnets";
+                "peer_id" => %enr.peer_id()
+            );
+        }
+        predicate
+    }
+}