Silky smooth discovery (#1274)

* Initial structural re-write

* Improving discovery update and correcting attestation service logic

* Rework discovery.mod

* Handling lifetimes of query futures

* Discovery update first draft

* format fixes

* Stabalise discv5 update

* Formatting corrections

* Limit FindPeers queries and bug correction

* Update to stable release discv5

* Remove unnecessary pin

* formatting

beacon_node/eth2_libp2p/src/config.rs

@@ -0,0 +1,144 @@
+use crate::types::GossipKind;
+use crate::Enr;
+use discv5::{Discv5Config, Discv5ConfigBuilder};
+use libp2p::gossipsub::{GossipsubConfig, GossipsubConfigBuilder, GossipsubMessage, MessageId};
+use libp2p::Multiaddr;
+use serde_derive::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
+use std::path::PathBuf;
+use std::time::Duration;
+
+pub const GOSSIP_MAX_SIZE: usize = 1_048_576;
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+#[serde(default)]
+/// Network configuration for lighthouse.
+pub struct Config {
+    /// Data directory where node's keyfile is stored
+    pub network_dir: PathBuf,
+
+    /// IP address to listen on.
+    pub listen_address: std::net::IpAddr,
+
+    /// The TCP port that libp2p listens on.
+    pub libp2p_port: u16,
+
+    /// UDP port that discovery listens on.
+    pub discovery_port: u16,
+
+    /// The address to broadcast to peers about which address we are listening on. None indicates
+    /// that no discovery address has been set in the CLI args.
+    pub enr_address: Option<std::net::IpAddr>,
+
+    /// The udp port to broadcast to peers in order to reach back for discovery.
+    pub enr_udp_port: Option<u16>,
+
+    /// The tcp port to broadcast to peers in order to reach back for libp2p services.
+    pub enr_tcp_port: Option<u16>,
+
+    /// Target number of connected peers.
+    pub max_peers: usize,
+
+    /// A secp256k1 secret key, as bytes in ASCII-encoded hex.
+    ///
+    /// With or without `0x` prefix.
+    #[serde(skip)]
+    pub secret_key_hex: Option<String>,
+
+    /// Gossipsub configuration parameters.
+    #[serde(skip)]
+    pub gs_config: GossipsubConfig,
+
+    /// Discv5 configuration parameters.
+    #[serde(skip)]
+    pub discv5_config: Discv5Config,
+
+    /// List of nodes to initially connect to.
+    pub boot_nodes: Vec<Enr>,
+
+    /// List of libp2p nodes to initially connect to.
+    pub libp2p_nodes: Vec<Multiaddr>,
+
+    /// Client version
+    pub client_version: String,
+
+    /// List of extra topics to initially subscribe to as strings.
+    pub topics: Vec<GossipKind>,
+
+    /// Introduces randomization in network propagation of messages. This should only be set for
+    /// testing purposes and will likely be removed in future versions.
+    // TODO: Remove this functionality for mainnet
+    pub propagation_percentage: Option<u8>,
+}
+
+impl Default for Config {
+    /// Generate a default network configuration.
+    fn default() -> Self {
+        let mut network_dir = dirs::home_dir().unwrap_or_else(|| PathBuf::from("."));
+        network_dir.push(".lighthouse");
+        network_dir.push("network");
+
+        // The default topics that we will initially subscribe to
+        let topics = vec![
+            GossipKind::BeaconBlock,
+            GossipKind::BeaconAggregateAndProof,
+            GossipKind::VoluntaryExit,
+            GossipKind::ProposerSlashing,
+            GossipKind::AttesterSlashing,
+        ];
+
+        // The function used to generate a gossipsub message id
+        // We use base64(SHA256(data)) for content addressing
+        let gossip_message_id = |message: &GossipsubMessage| {
+            MessageId(base64::encode_config(
+                &Sha256::digest(&message.data),
+                base64::URL_SAFE_NO_PAD,
+            ))
+        };
+
+        // gossipsub configuration
+        // Note: The topics by default are sent as plain strings. Hashes are an optional
+        // parameter.
+        let gs_config = GossipsubConfigBuilder::new()
+            .max_transmit_size(GOSSIP_MAX_SIZE)
+            .heartbeat_interval(Duration::from_secs(1))
+            .manual_propagation() // require validation before propagation
+            .no_source_id()
+            .message_id_fn(gossip_message_id)
+            .build();
+
+        // discv5 configuration
+        let discv5_config = Discv5ConfigBuilder::new()
+            .enable_packet_filter()
+            .session_cache_capacity(100)
+            .request_timeout(Duration::from_secs(4))
+            .request_retries(2)
+            .enr_peer_update_min(2) // prevents NAT's should be raised for mainnet
+            .query_parallelism(5)
+            .query_timeout(Duration::from_secs(60))
+            .query_peer_timeout(Duration::from_secs(2))
+            .ip_limit() // limits /24 IP's in buckets.
+            .ping_interval(Duration::from_secs(300))
+            .build();
+
+        // NOTE: Some of these get overridden by the corresponding CLI default values.
+        Config {
+            network_dir,
+            listen_address: "0.0.0.0".parse().expect("valid ip address"),
+            libp2p_port: 9000,
+            discovery_port: 9000,
+            enr_address: None,
+            enr_udp_port: None,
+            enr_tcp_port: None,
+            max_peers: 50,
+            secret_key_hex: None,
+            gs_config,
+            discv5_config,
+            boot_nodes: vec![],
+            libp2p_nodes: vec![],
+            client_version: version::version(),
+            topics,
+            propagation_percentage: None,
+        }
+    }
+}