discv5 ============ [![Build Status]][Build Link] [![Doc Status]][Doc Link] [![Crates Status]][Crates Link] [Build Status]: https://github.com/sigp/discv5/workflows/build/badge.svg?branch=master [Build Link]: https://github.com/sigp/discv5/actions [Doc Status]: https://docs.rs/discv5/badge.svg [Doc Link]: https://docs.rs/discv5 [Crates Status]: https://img.shields.io/crates/v/discv5.svg [Crates Link]: https://crates.io/crates/discv5 [Documentation at docs.rs](https://docs.rs/discv5) # Overview This is a rust implementation of the [Discovery v5](https://github.com/ethereum/devp2p/blob/master/discv5/discv5.md) peer discovery protocol. Discovery v5 is a protocol designed for encrypted peer discovery and topic advertisement. Each peer/node on the network is identified via it's `ENR` ([Ethereum Node Record](https://eips.ethereum.org/EIPS/eip-778)), which is essentially a signed key-value store containing the node's public key and optionally IP address and port. Discv5 employs a kademlia-like routing table to store and manage discovered peers and topics. The protocol allows for external IP discovery in NAT environments through regular PING/PONG's with discovered nodes. Nodes return the external IP address that they have received and a simple majority is chosen as our external IP address. If an external IP address is updated, this is produced as an event to notify the swarm (if one is used for this behaviour). For a simple CLI discovery service see [discv5-cli](https://github.com/AgeManning/discv5-cli) # Usage A simple example of creating this service is as follows: ```rust use discv5::{enr, enr::{CombinedKey, NodeId}, TokioExecutor, Discv5, Discv5ConfigBuilder}; use std::net::SocketAddr; // listening address and port let listen_addr = "0.0.0.0:9000".parse::().unwrap(); // construct a local ENR let enr_key = CombinedKey::generate_secp256k1(); let enr = enr::EnrBuilder::new("v4").build(&enr_key).unwrap(); // build the tokio executor let mut runtime = tokio::runtime::Builder::new_multi_thread() .thread_name("Discv5-example") .enable_all() .build() .unwrap(); // default configuration let config = Discv5ConfigBuilder::new().build(); // construct the discv5 server let mut discv5 = Discv5::new(enr, enr_key, config).unwrap(); // In order to bootstrap the routing table an external ENR should be added // This can be done via add_enr. I.e.: // discv5.add_enr() // start the discv5 server runtime.block_on(discv5.start(listen_addr)); // run a find_node query runtime.block_on(async { let found_nodes = discv5.find_node(NodeId::random()).await.unwrap(); println!("Found nodes: {:?}", found_nodes); }); ```