iroh 1.2.0 & 1.3.0 - Small features for more user control

Welcome to a new release of iroh, a modular networking stack in Rust, for building direct connections between devices.

This blog post covers our last two releases: 1.2 and 1.3, which introduce a few small features that make iroh simpler to work with and able to run in more places.

iroh v1.2.0

n0-dns-resolver

We've reduced our binary size by more than 10% by switching our DNS resolver from hickory-resolver to n0-dns-resolver. This lets iroh run on even smaller devices. For example, iroh now works on ESP32 with 4 MiB of flash, out of the box.

We've also added features to make DNS resolution more configurable.

Previously, iroh always fell back to Google's nameservers when it couldn't read the system DNS configuration. Now, you can add custom fallback DNS nameservers using iroh::dns::Builder::fallback_nameserver_configs, and set the FallbackMode using iroh::dns::Builder::with_fallback_mode.

iroh::dns::Builder::with_nameserver and iroh::dns::Builder::with_nameservers have been deprecated in favor of iroh::dns::Builder::add_nameserver_config and iroh::dns::Builder::add_nameserver_configs.

The fallback modes include:

• Deferred (the default): the fallback nameservers will be queried only after every configured primary nameserver has failed or timed out.
• Eager: the fallback and primary nameservers are queried at the same time.
• IfSystemEmpty: queries the fallback nameservers only if the system config returns no nameservers.
• Never: never queries any fallbacks. This can also be set with iroh::dns::Builder::disable_fallback.

Now, you have more control over the exact behaviour the DNS resolver should take when the configured DNS nameservers or the system config nameservers aren't cutting it.

See PR #4419 and PR #4506 for more details.

Relay Auth Denied

In most cases, when a connection to a relay server dies, iroh attempts to redial the connection, assuming that the connection died because of a network change. These failures are not fatal; iroh will just reconnect.

However, if dialing a relay fails because you are not authorized to connect to that relay – that's a fatal error. RelayStatus::auth_denied_reason only returns Some if your connection was denied because of authentication, and it allows you to inspect why it failed.

use iroh::{Endpoint, Watcher, endpoint::presets};
use n0_future::StreamExt;

let endpoint = Endpoint::builder(presets::Minimal).bind().await?;
let mut status = endpoint.home_relay_status().stream();
while let Some(relays) = status.next().await {
    for relay in relays {
        if let Some(reason) = relay.auth_denied_reason() {
            println!("{}: authentication denied ({reason})", relay.url());
        }
    }
}

See PR #4501 for more details.

iroh v1.3.0

APIs For Batching Datagrams

noq, the underlying QUIC implementation that iroh uses, added a way to batch sending and receiving datagrams.

Using iroh::endpoint::Connection::send_many_datagrams and iroh::endpoint::Connection::read_many_datagrams gives you a performance boost when sending bursts of datagrams, since the entire batch is handled with one lock and one driver wake-up.

Thank you contributor ifdario, see PR #4547 for more details.

Order Your ALPNs

Previously, we held the configured protocols in the Router in a BTreeMap, so ALPNs were sent in alphabetical order. This means that if you had myproto/1 and myproto/2, the first would always win out in protocol negotiation.

Now, the protocols are ordered in the order they are added to the iroh::protocol::Router, so register your preferred protocol first.

See PR #4533 for more details.

Fix Blocked Actor

Thanks to contributor William-Herly for fixing a bug where a full relay send queue could stall a connection while sending its Initial packet.

See PR #4512 for more details.

What's Next?

We expect the next few releases to keep this rhythm: happy maintenance releases every few weeks, with small fixes for corner cases and invisible improvements. However, we are gearing up to add some new, bigger features to iroh before the end of the year. As always, the full details are in the changelogs for iroh 1.2.0 and iroh 1.3.0.

See you at the next release, and keep filing those bugs!