The fastest route is a direct connection, so if necessary, iroh tries to hole-punch. Should this fail, it can fall back to an open ecosystem of public relay servers.
Iroh uses noq to establish QUIC connections between endpoints. This way you get authenticated encryption, concurrent streams with stream priorities, a datagram transport and avoid head-of-line-blocking out of the box.
Use pre-existing protocols built on iroh instead of writing your own: iroh-blobs for BLAKE3-based content-addressed blob transfer, iroh-gossip for publish-subscribe overlay networks, and iroh-docs for eventually-consistent key-value stores.
Crates.io
Discord
YouTube
const ALPN: &[u8] = b"iroh-example/echo/0";
let endpoint = Endpoint::bind().await?;
// Open a connection to the accepting endpoint
let conn = endpoint.connect(addr, ALPN).await?;
// Open a bidirectional QUIC stream
let (mut send, mut recv) = conn.open_bi().await?;
// Send some data to be echoed
send.write_all(b"Hello, world!").await?;
send.finish()?;
// Receive the echo
let response = recv.read_to_end(1000).await?;
assert_eq!(&response, b"Hello, world!");
// As the side receiving the last application data - say goodbye
conn.close(0u32.into(), b"bye!");
// Close the endpoint and all its connections
endpoint.close().await;