0g-storage-node/version-meld/discv5/examples/simple_server.rs

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2024-01-03 10:24:52 +00:00
//! Demonstrates how to run a basic Discovery v5 Service.
//!
//! This example simply starts a discovery server and listens to events that the server emits.
//!
//!
//! It can be bootstrapped to a DHT by providing an ENR to add to its DHT.
//!
//! To run this example simply run:
//! ```
//! $ cargo run --example simple_server -- <ENR-IP> <ENR-PORT> <BASE64ENR>
//! ```
use discv5::{enr, enr::CombinedKey, Discv5, Discv5Config, Discv5Event};
use std::net::{Ipv4Addr, SocketAddr};
#[tokio::main]
async fn main() {
// allows detailed logging with the RUST_LOG env variable
let filter_layer = tracing_subscriber::EnvFilter::try_from_default_env()
.or_else(|_| tracing_subscriber::EnvFilter::try_new("info"))
.unwrap();
let _ = tracing_subscriber::fmt()
.with_env_filter(filter_layer)
.try_init();
// if there is an address specified use it
let address = std::env::args()
.nth(1)
.map(|addr| addr.parse::<Ipv4Addr>().unwrap());
let port = {
if let Some(udp_port) = std::env::args().nth(2) {
udp_port.parse().unwrap()
} else {
9000
}
};
// listening address and port
let listen_addr = "0.0.0.0:9000".parse::<SocketAddr>().unwrap();
let enr_key = CombinedKey::generate_secp256k1();
// construct a local ENR
let enr = {
let mut builder = enr::EnrBuilder::new("v4");
// if an IP was specified, use it
if let Some(external_address) = address {
builder.ip(external_address.into());
}
// if a port was specified, use it
if std::env::args().nth(2).is_some() {
builder.udp(port);
}
builder.build(&enr_key).unwrap()
};
// if the ENR is useful print it
println!("Node Id: {}", enr.node_id());
if enr.udp_socket().is_some() {
println!("Base64 ENR: {}", enr.to_base64());
println!("IP: {}, UDP_PORT:{}", enr.ip().unwrap(), enr.udp().unwrap());
} else {
println!("ENR is not printed as no IP:PORT was specified");
}
// default configuration
let config = Discv5Config::default();
// construct the discv5 server
let mut discv5 = Discv5::new(enr, enr_key, config).unwrap();
// if we know of another peer's ENR, add it known peers
if let Some(base64_enr) = std::env::args().nth(3) {
match base64_enr.parse::<enr::Enr<enr::CombinedKey>>() {
Ok(enr) => {
println!(
"ENR Read. ip: {:?}, udp_port {:?}, tcp_port: {:?}",
enr.ip(),
enr.udp(),
enr.tcp()
);
if let Err(e) = discv5.add_enr(enr) {
println!("ENR was not added: {}", e);
}
}
Err(e) => panic!("Decoding ENR failed: {}", e),
}
}
// start the discv5 service
discv5.start(listen_addr).await.unwrap();
println!("Server started");
// get an event stream
let mut event_stream = discv5.event_stream().await.unwrap();
loop {
match event_stream.recv().await {
Some(Discv5Event::SocketUpdated(addr)) => {
println!("Nodes ENR socket address has been updated to: {:?}", addr);
}
Some(Discv5Event::Discovered(enr)) => {
println!("A peer has been discovered: {}", enr.node_id());
}
_ => {}
}
}
}