lighthouse/beacon_node/lighthouse_network/src/gossipsub/mod.rs

//! Implementation of the [Gossipsub](https://github.com/libp2p/specs/blob/master/pubsub/gossipsub/README.md) protocol.
//!
//! Gossipsub is a P2P pubsub (publish/subscription) routing layer designed to extend upon
//! floodsub and meshsub routing protocols.
//!
//! # Overview
//!
//! *Note: The gossipsub protocol specifications
//! (<https://github.com/libp2p/specs/tree/master/pubsub/gossipsub>) provide an outline for the
//! routing protocol. They should be consulted for further detail.*
//!
//! Gossipsub  is a blend of meshsub for data and randomsub for mesh metadata. It provides bounded
//! degree and amplification factor with the meshsub construction and augments it using gossip
//! propagation of metadata with the randomsub technique.
//!
//! The router maintains an overlay mesh network of peers on which to efficiently send messages and
//! metadata.  Peers use control messages to broadcast and request known messages and
//! subscribe/unsubscribe from topics in the mesh network.
//!
//! # Important Discrepancies
//!
//! This section outlines the current implementation's potential discrepancies from that of other
//! implementations, due to undefined elements in the current specification.
//!
//! - **Topics** -  In gossipsub, topics configurable by the `hash_topics` configuration parameter.
//! Topics are of type [`TopicHash`]. The current go implementation uses raw utf-8 strings, and this
//! is default configuration in rust-libp2p. Topics can be hashed (SHA256 hashed then base64
//! encoded) by setting the `hash_topics` configuration parameter to true.
//!
//! - **Sequence Numbers** - A message on the gossipsub network is identified by the source
//! [`PeerId`](libp2p_identity::PeerId) and a nonce (sequence number) of the message. The sequence numbers in
//! this implementation are sent as raw bytes across the wire. They are 64-bit big-endian unsigned
//! integers. When messages are signed, they are monotonically increasing integers starting from a
//! random value and wrapping around u64::MAX. When messages are unsigned, they are chosen at random.
//! NOTE: These numbers are sequential in the current go implementation.
//!
//! # Peer Discovery
//!
//! Gossipsub does not provide peer discovery by itself. Peer discovery is the process by which
//! peers in a p2p network exchange information about each other among other reasons to become resistant
//! against the failure or replacement of the
//! [boot nodes](https://docs.libp2p.io/reference/glossary/#boot-node) of the network.
//!
//! Peer
//! discovery can e.g. be implemented with the help of the [Kademlia](https://github.com/libp2p/specs/blob/master/kad-dht/README.md) protocol
//! in combination with the [Identify](https://github.com/libp2p/specs/tree/master/identify) protocol. See the
//! Kademlia implementation documentation for more information.
//!
//! # Using Gossipsub
//!
//! ## Gossipsub Config
//!
//! The [`Config`] struct specifies various network performance/tuning configuration
//! parameters. Specifically it specifies:
//!
//! [`Config`]: struct.Config.html
//!
//! This struct implements the [`Default`] trait and can be initialised via
//! [`Config::default()`].
//!
//!
//! ## Behaviour
//!
//! The [`Behaviour`] struct implements the [`libp2p_swarm::NetworkBehaviour`] trait allowing it to
//! act as the routing behaviour in a [`libp2p_swarm::Swarm`]. This struct requires an instance of
//! [`PeerId`](libp2p_identity::PeerId) and [`Config`].
//!
//! [`Behaviour`]: struct.Behaviour.html

//! ## Example
//!
//! For an example on how to use gossipsub, see the [chat-example](https://github.com/libp2p/rust-libp2p/tree/master/examples/chat).

#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]

mod backoff;
mod behaviour;
mod config;
mod error;
mod gossip_promises;
mod handler;
mod mcache;
mod metrics;
mod peer_score;
mod protocol;
mod rpc_proto;
mod subscription_filter;
mod time_cache;
mod topic;
mod transform;
mod types;

pub use self::behaviour::{Behaviour, Event, MessageAuthenticity};
pub use self::config::{Config, ConfigBuilder, ValidationMode, Version};
pub use self::error::{ConfigBuilderError, PublishError, SubscriptionError, ValidationError};
pub use self::metrics::Config as MetricsConfig;
pub use self::peer_score::{
    score_parameter_decay, score_parameter_decay_with_base, PeerScoreParams, PeerScoreThresholds,
    TopicScoreParams,
};
pub use self::subscription_filter::{
    AllowAllSubscriptionFilter, CallbackSubscriptionFilter, CombinedSubscriptionFilters,
    MaxCountSubscriptionFilter, RegexSubscriptionFilter, TopicSubscriptionFilter,
    WhitelistSubscriptionFilter,
};
pub use self::topic::{Hasher, Topic, TopicHash};
pub use self::transform::{DataTransform, IdentityTransform};
pub use self::types::{Message, MessageAcceptance, MessageId, RawMessage};
pub type IdentTopic = Topic<self::topic::IdentityHash>;
pub type Sha256Topic = Topic<self::topic::Sha256Hash>;
pub use self::types::FailedMessages;