Crate mdns

Multicast DNS library with built-in networking.

This crate can be used to discover mDNS devices that are listening on a network.

Basic usage

This example finds all Chromecast devices on the same LAN as the executing computer.

Once the devices are discovered, they respond with standard DNS records, with a few minor low-level protocol differences.

The only Chromecast-specific piece of code here is the SERVICE_NAME. In order to discover other types of devices, simply change the service name to the one your device uses.

This example obtains the IP addresses of the cast devices by looking up A/AAAA records.

use futures_util::{pin_mut, stream::StreamExt};
use mdns::{Error, Record, RecordKind};
use std::{net::IpAddr, time::Duration};

/// The hostname of the devices we are searching for.
/// Every Chromecast will respond to the service name in this example.
const SERVICE_NAME: &'static str = "_googlecast._tcp.local";

#[async_std::main]
async fn main() -> Result<(), Error> {
    // Iterate through responses from each Cast device, asking for new devices every 15s
    let stream = mdns::discover::all(SERVICE_NAME, Duration::from_secs(15))?.listen();
    pin_mut!(stream);

    while let Some(Ok(response)) = stream.next().await {
        let addr = response.records()
                           .filter_map(self::to_ip_addr)
                           .next();

        if let Some(addr) = addr {
            println!("found cast device at {}", addr);
        } else {
            println!("cast device does not advertise address");
        }
    }

    Ok(())
}

fn to_ip_addr(record: &Record) -> Option<IpAddr> {
    match record.kind {
        RecordKind::A(addr) => Some(addr.into()),
        RecordKind::AAAA(addr) => Some(addr.into()),
        _ => None,
    }
}

Modules

discover	Utilities for discovering devices on the LAN.
resolve	Utilities for resolving a devices on the LAN.

Structs

Record	Any type of DNS record.
Response	A DNS response.
mDNSListener	An mDNS listener on a specific interface.

Enums

Error
RecordKind	A specific DNS record variant.