[][src]Crate libp2p

Libp2p is a peer-to-peer framework.

Major libp2p concepts

Here is a list of all the major concepts of libp2p.

Multiaddr

A Multiaddr is a way to reach a node. Examples:

  • /ip4/80.123.90.4/tcp/5432
  • /ip6/[::1]/udp/10560/quic
  • /unix//path/to/socket

Transport

Transport is a trait that represents an object capable of dialing multiaddresses or listening on multiaddresses. The Transport produces an output which varies depending on the object that implements the trait.

Each implementation of Transport typically supports only some multiaddresses. For example the TcpConfig type (which implements Transport) only supports multiaddresses of the format /ip4/.../tcp/....

Example:

use libp2p::{Multiaddr, Transport, tcp::TcpConfig};
let tcp = TcpConfig::new();
let addr: Multiaddr = "/ip4/98.97.96.95/tcp/20500".parse().expect("invalid multiaddr");
let _outgoing_connec = tcp.dial(addr);
// Note that `_outgoing_connec` is a `Future`, and therefore doesn't do anything by itself
// unless it is run through a tokio runtime.

The easiest way to create a transport is to use the build_development_transport function. This function provides support for the most common protocols.

Example:

let key = libp2p::secio::SecioKeyPair::ed25519_generated().unwrap();
let _transport = libp2p::build_development_transport(key);
// _transport.dial(...);

See the documentation of the libp2p-core crate for more details about transports.

Connection upgrades

Once a connection has been opened with a remote through a Transport, it can be upgraded. This consists in negotiating a protocol with the remote (through a negotiation protocol multistream-select), and applying that protocol on the socket.

Example:

use libp2p::{Transport, tcp::TcpConfig, secio::{SecioConfig, SecioKeyPair}};
let tcp = TcpConfig::new();
let secio_upgrade = SecioConfig::new(SecioKeyPair::ed25519_generated().unwrap());
let with_security = tcp.with_upgrade(secio_upgrade);
// let _ = with_security.dial(...);
// `with_security` also implements the `Transport` trait, and all the connections opened
// through it will automatically negotiate the `secio` protocol.

See the documentation of the libp2p-core crate for more details about upgrades.

Topology

The Topology trait is implemented for types that hold the layout of a network. When other components need the network layout to operate, they are passed an instance of a Topology.

The most basic implementation of Topology is the MemoryTopology, which is essentially a HashMap. Creating your own Topology makes it possible to add for example a reputation system.

Network behaviour

The NetworkBehaviour trait is implemented on types that provide some capability to the network. Examples of network behaviours include: periodically ping the nodes we are connected to, periodically ask for information from the nodes we are connected to, connect to a DHT and make queries to it, propagate messages to the nodes we are connected to (pubsub), and so on.

Swarm

The Swarm struct contains all active and pending connections to remotes and manages the state of all the substreams that have been opened, and all the upgrades that were built upon these substreams.

It combines a Transport, a NetworkBehaviour and a Topology together.

See the documentation of the libp2p-core crate for more details about creating a swarm.

Using libp2p

This section contains details about how to use libp2p in practice.

The most simple way to use libp2p consists in the following steps:

  • Create a base implementation of Transport that combines all the protocols you want and the upgrades you want, such as the security layer and multiplexing.
  • Create a struct that implements the NetworkBehaviour trait and that combines all the network behaviours that you want.
  • Create and implement the Topology trait that to store the topology of the network.
  • Create a swarm that combines your base transport, the network behaviour, and the topology.
  • This swarm can now be polled with the tokio library in order to start the network.

Re-exports

pub extern crate bytes;
pub extern crate futures;
pub extern crate multiaddr;
pub extern crate multihash;
pub extern crate tokio_io;
pub extern crate tokio_codec;
pub extern crate libp2p_core as core;
pub extern crate libp2p_dns as dns;
pub extern crate libp2p_identify as identify;
pub extern crate libp2p_kad as kad;
pub extern crate libp2p_floodsub as floodsub;
pub extern crate libp2p_mplex as mplex;
pub extern crate libp2p_mdns as mdns;
pub extern crate libp2p_ping as ping;
pub extern crate libp2p_plaintext as plaintext;
pub extern crate libp2p_ratelimit as ratelimit;
pub extern crate libp2p_secio as secio;
pub extern crate libp2p_tcp as tcp;
pub extern crate libp2p_uds as uds;
pub extern crate libp2p_websocket as websocket;
pub extern crate libp2p_yamux as yamux;
pub use libp2p_core_derive::NetworkBehaviour;
pub use self::simple::SimpleProtocol;

Modules

simple

Macros

multiaddr

The multiaddr! macro is an easy way for a user to create a Multiaddr.

Structs

Multiaddr

Representation of a Multiaddr.

PeerId

Identifier of a peer of the network.

Swarm

Contains the state of the network, plus the way it should behave.

Enums

TransportError

Error that can happen when dialing or listening.

Traits

InboundUpgrade

Possible upgrade on an inbound connection or substream.

InboundUpgradeExt

Extension trait for InboundUpgrade. Automatically implemented on all types that implement InboundUpgrade.

OutboundUpgrade

Possible upgrade on an outbound connection or substream.

OutboundUpgradeExt

Extention trait for OutboundUpgrade. Automatically implemented on all types that implement OutboundUpgrade.

Transport

A transport is an object that can be used to produce connections by listening or dialing a peer.

TransportExt

Trait automatically implemented on all objects that implement Transport. Provides some additional utilities.

Functions

build_development_transport

Builds a Transport that supports the most commonly-used protocols that libp2p supports.

build_tcp_ws_secio_mplex_yamux

Builds an implementation of Transport that is suitable for usage with the Swarm.