rust-libp2p/examples/mdns-passive-discovery.rs

// Copyright 2018 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
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// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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use libp2p::{identity, mdns::{Mdns, MdnsConfig, MdnsEvent}, PeerId, Swarm};
use std::error::Error;

#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    env_logger::init();

    // Create a random PeerId.
    let id_keys = identity::Keypair::generate_ed25519();
    let peer_id = PeerId::from(id_keys.public());
    println!("Local peer id: {:?}", peer_id);

    // Create a transport.
    let transport = libp2p::build_development_transport(id_keys)?;

    // Create an MDNS network behaviour.
    let behaviour = Mdns::new(MdnsConfig::default()).await?;

    // Create a Swarm that establishes connections through the given transport.
    // Note that the MDNS behaviour itself will not actually inititiate any connections,
    // as it only uses UDP.
    let mut swarm = Swarm::new(transport, behaviour, peer_id);
    Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse()?)?;

    loop {
        match swarm.next().await {
            MdnsEvent::Discovered(peers) => {
                for (peer, addr) in peers {
                    println!("discovered {} {}", peer, addr);
                }
            }
            MdnsEvent::Expired(expired) => {
                for (peer, addr) in expired {
                    println!("expired {} {}", peer, addr);
                }
            }
        }
    }
}