nym/sdk/rust/nym-sdk/examples/libp2p_chat/main.rs

// Copyright 2018 Parity Technologies (UK) Ltd.
//
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//! A basic chat application with logs demonstrating libp2p and the gossipsub protocol
//! combined with mDNS for the discovery of peers to gossip with.
//!
//! Using two terminal windows, start two instances, typing the following in each:
//!
//! ```sh
//! cargo run
//! ```
//!
//! Mutual mDNS discovery may take a few seconds. When each peer does discover the other
//! it will print a message like:
//!
//! ```sh
//! mDNS discovered a new peer: {peerId}
//! ```
//!
//! Type a message and hit return: the message is sent and printed in the other terminal.
//! Close with Ctrl-c.
//!
//! You can open more terminal windows and add more peers using the same line above.
//!
//! Once an additional peer is mDNS discovered it can participate in the conversation
//! and all peers will receive messages sent from it.
//!
//! If a participant exits (Control-C or otherwise) the other peers will receive an mDNS expired
//! event and remove the expired peer from the list of known peers.

use crate::rust_libp2p_nym::transport::NymTransport;
use futures::{prelude::*, select};
use libp2p::Multiaddr;
use libp2p::{
    core::muxing::StreamMuxerBox,
    gossipsub, identity,
    swarm::NetworkBehaviour,
    swarm::{SwarmBuilder, SwarmEvent},
    PeerId, Transport,
};
use log::{error, info, LevelFilter};
use nym_sdk::mixnet::MixnetClient;
use std::collections::hash_map::DefaultHasher;
use std::error::Error;
use std::hash::{Hash, Hasher};
use std::time::Duration;
use tokio::io;
use tokio_util::codec;

#[path = "../libp2p_shared/lib.rs"]
mod rust_libp2p_nym;

// We create a custom network behaviour that uses Gossipsub
#[derive(NetworkBehaviour)]
struct Behaviour {
    gossipsub: gossipsub::Behaviour,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    pretty_env_logger::formatted_timed_builder()
        .filter_level(LevelFilter::Warn)
        .filter(Some("libp2p_chat"), LevelFilter::Info)
        .init();

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

    // To content-address message, we can take the hash of message and use it as an ID.
    let message_id_fn = |message: &gossipsub::Message| {
        let mut s = DefaultHasher::new();
        message.data.hash(&mut s);
        gossipsub::MessageId::from(s.finish().to_string())
    };

    // Set a custom gossipsub configuration
    let gossipsub_config = gossipsub::ConfigBuilder::default()
        .heartbeat_interval(Duration::from_secs(10)) // This is set to aid debugging by not cluttering the log space
        .validation_mode(gossipsub::ValidationMode::Strict) // This sets the kind of message validation. The default is Strict (enforce message signing)
        .message_id_fn(message_id_fn) // content-address messages. No two messages of the same content will be propagated.
        .build()
        .expect("Valid config");

    // build a gossipsub network behaviour
    let mut gossipsub = gossipsub::Behaviour::new(
        gossipsub::MessageAuthenticity::Signed(id_keys),
        gossipsub_config,
    )
    .expect("Correct configuration");
    // Create a Gossipsub topic
    let topic = gossipsub::IdentTopic::new("test-net");
    // subscribes to our topic
    gossipsub.subscribe(&topic)?;

    let client = MixnetClient::connect_new().await.unwrap();
    info!("client address: {}", client.nym_address());

    let local_key = identity::Keypair::generate_ed25519();
    let local_peer_id = PeerId::from(local_key.public());
    info!("Local peer id: {local_peer_id:?}");

    let transport = NymTransport::new(client, local_key).await?;

    let mut swarm = SwarmBuilder::with_tokio_executor(
        transport
            .map(|a, _| (a.0, StreamMuxerBox::new(a.1)))
            .boxed(),
        Behaviour { gossipsub },
        local_peer_id,
    )
    .build();

    if let Some(addr) = std::env::args().nth(1) {
        let remote: Multiaddr = addr.parse()?;
        swarm.dial(remote)?;
        info!("Dialed {addr}")
    }

    // Read full lines from stdin
    let mut stdin = codec::FramedRead::new(io::stdin(), codec::LinesCodec::new()).fuse();

    info!("Enter messages via STDIN and they will be sent to connected peers using Gossipsub");

    // Kick it off
    loop {
        select! {
            line = stdin.select_next_some() => {
                if let Err(e) = swarm
                    .behaviour_mut().gossipsub
                    .publish(topic.clone(), line.expect("Stdin not to close").as_bytes()) {
                    error!("Publish error: {e:?}");
                }
            },
            event = swarm.select_next_some() => {
                match event {
                    SwarmEvent::Behaviour(BehaviourEvent::Gossipsub(gossipsub::Event::Message {
                        propagation_source: peer_id,
                        message_id: id,
                        message,
                    })) => info!(
                            "Got message: '{}' with id: {id} from peer: {peer_id}",
                            String::from_utf8_lossy(&message.data),
                        ),
                    SwarmEvent::NewListenAddr { address, .. } => {
                        info!("Local node is listening on {address}");
                    }
                    other => {info!("other event: {:?}", other)}
                }
            }
        }
    }
}