feat: rust peer joins peer discovery topic (#174)

* feat: rust peer discovery over gossipsub

* chore: fmt

rust-peer/src/main.rs

@@ -42,6 +42,7 @@ const LOCAL_KEY_PATH: &str = "./local_key";
 const LOCAL_CERT_PATH: &str = "./cert.pem";
 const GOSSIPSUB_CHAT_TOPIC: &str = "universal-connectivity";
 const GOSSIPSUB_CHAT_FILE_TOPIC: &str = "universal-connectivity-file";
+const GOSSIPSUB_PEER_DISCOVERY: &str = "universal-connectivity-browser-peer-discovery";
 const BOOTSTRAP_NODES: [&str; 4] = [
     "/dnsaddr/bootstrap.libp2p.io/p2p/QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN",
     "/dnsaddr/bootstrap.libp2p.io/p2p/QmQCU2EcMqAqQPR2i9bChDtGNJchTbq5TbXJJ16u19uLTa",
@@ -113,6 +114,7 @@ async fn main() -> Result<()> {
 
     let chat_topic_hash = gossipsub::IdentTopic::new(GOSSIPSUB_CHAT_TOPIC).hash();
     let file_topic_hash = gossipsub::IdentTopic::new(GOSSIPSUB_CHAT_FILE_TOPIC).hash();
+    let peer_discovery_hash = gossipsub::IdentTopic::new(GOSSIPSUB_PEER_DISCOVERY).hash();
 
     let mut tick = futures_timer::Delay::new(TICK_INTERVAL);
 
@@ -181,6 +183,11 @@ async fn main() -> Result<()> {
                         continue;
                     }
 
+                    if message.topic == peer_discovery_hash {
+                        info!("Received peer discovery from {:?}", message.source);
+                        continue;
+                    }
+
                     error!("Unexpected gossipsub topic hash: {:?}", message.topic);
                 }
                 SwarmEvent::Behaviour(BehaviourEvent::Gossipsub(
@@ -335,6 +342,7 @@ fn create_swarm(
     // Create/subscribe Gossipsub topics
     gossipsub.subscribe(&gossipsub::IdentTopic::new(GOSSIPSUB_CHAT_TOPIC))?;
     gossipsub.subscribe(&gossipsub::IdentTopic::new(GOSSIPSUB_CHAT_FILE_TOPIC))?;
+    gossipsub.subscribe(&gossipsub::IdentTopic::new(GOSSIPSUB_PEER_DISCOVERY))?;
 
     let transport = {
         let webrtc = webrtc::tokio::Transport::new(local_key.clone(), certificate);