Discovery in 0.4

Discovery listens for UDP device announcements and sends active probes on demand. Share one instance across your devices. Discovery is IPv4 broadcast based; use an explicit address where broadcast discovery cannot reach a device.

Scan and connect

use std::time::Duration;
use rustuya::tokio::{Device, Discovery};

#[tokio::main]
async fn main() -> rustuya::tokio::Result<()> {
    let discovery = Discovery::new()?;
    for info in discovery.scan(Duration::from_secs(5)).await {
        println!("{} at {} ({:?})", info.id, info.ip, info.version);
    }

    let dev = Device::builder("device_id_22chars0000", "0123456789abcdef")
        .discover(&discovery, Duration::from_secs(10))
        .await?;
    dev.wait_connected(Duration::from_secs(10)).await?;
    println!("Connected to {}", dev.id());
    dev.close().await;
    discovery.close().await;
    Ok(())
}

discover() resolves the IP and reported protocol version, then links discovery for reconnect wakes and later IP changes. With a known IP, use Device::builder(id, key).address(ip).rediscover(&discovery).connect().

Discovery APIs

Method	Use
scan(window).await	Trigger an active probe round and collect devices during the window
find(id, timeout).await	Resolve a device, using cached information if present
known()	Snapshot of devices retained in the driver’s cache
last_seen(id)	Age of the most recent announcement
discovered()	Subscribe to discovery events
request_scan()	Request an on-demand active probe round

There is no process-global scanner. Re-announcements route directly to linked devices; a changed IP updates the next dial target. Cache presence is not proof that a device is currently reachable—use last_seen and connection state.

Interfaces, bounds and source checks

The builder’s local_ip / local_ips options select the source addresses for active probing on multi-interface hosts. ports() changes receive ports; active probes still target the protocol’s standard ports (6666, 6667 and 7000).

Announcements are not authenticated by a device’s local key. By default, require_source_match(true) checks that the announced IP equals the UDP source. Only disable that check when an intentional relay requires it. max_devices bounds discovery cache entries (default 16,384).