Discover

Utility crate for advertising and discovering services on the local network over mDNS.

Features

• Broadcasts HTTP/HTTPS or TCP/UDP services with a role tag and advertised transport.
• Discovers peers by name and role, returning base URLs using the discovery-provided transport when present.
• Uses a short idle timeout so discovery returns promptly when nothing is present.

Usage

Registering a service for discovery

use discover::prelude::*;

let mut discovery = Discover::new(
    "my_role",    // publishing role
    "my_service", // service name
    "instance-1", // unique identifier
    8080,         // port
    false,        // udp?
    true,         // https?
);

// Broadcast over mDNS
discovery.publish().await?;

// Later, shut down the broadcaster
discovery.stop().await?;

Discovering peers

Discover::search browses mDNS for services that match a name/role and returns their Discover metadata, one entry per discovered base URL (accessible via address). It stops if nothing is found for one second.

use discover::prelude::*;

let peers = Discover::search(Browse::new(
    None,                              // service name (None = all mDNS services)
    Some("agent"),                     // role to match (None to ignore)
    false,                             // udp?
    false,                             // https? (used as a fallback when transport isn't advertised)
    std::time::Duration::from_secs(1), // idle timeout
))
.await?;

for peer in peers {
    println!("Found peer at {}", peer.address);
}

Behavior notes

• Local interfaces are collected via if_addrs; publishing fails (with a typed error) if interface enumeration fails or no non-loopback addresses exist.
• Discovery results are not HTTP-validated; perform any health checks yourself after discovery if needed.
• URLs in the discovery result include a trailing / (e.g. http://192.168.1.10:8080/).
• The final Duration in Browse::new controls how long discovery waits for mDNS responses after the last event.
• Discovery prefers the publisher’s advertised transport property (http or https), falling back to the https flag on Browse only when the property is missing.
• Passing None for the service name will first discover all advertised mDNS service types, then browse each one (with the same idle timeout).

Errors

• Mdns: Underlying mdns_sd error when creating, browsing, registering, or shutting down.
• MdnsChannelClosed: The browse channel closed unexpectedly during discovery.
• InterfaceEnumerationFailed(std::io::Error): Failed to enumerate network interfaces via if_addrs.
• NoUsableInterfaces: No non-loopback, non-link-local IP addresses were found to publish on.