<div align="center">
<h1>hick-embassy</h1>
</div>
<div align="center">
Async **mDNS / DNS-SD** for the [embassy] runtime — responder, querier, and
discovery on embassy-net, `no_std` + `alloc`.
[<img alt="github" src="https://img.shields.io/badge/github-al8n/hick-8da0cb?style=for-the-badge&logo=Github" height="22">][Github-url]
<img alt="LoC" src="https://img.shields.io/endpoint?url=https%3A%2F%2Fgist.githubusercontent.com%2Fal8n%2F327b2a8aef9003246e45c6e47fe63937%2Fraw%2Fhick-embassy" height="22">
[<img alt="Build" src="https://img.shields.io/github/actions/workflow/status/al8n/hick/ci.yml?logo=Github-Actions&style=for-the-badge" height="22">][CI-url]
[<img alt="codecov" src="https://img.shields.io/codecov/c/gh/al8n/hick?style=for-the-badge&token=6R3QFWRWHL&logo=codecov" height="22">][codecov-url]
[<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-hick--embassy-66c2a5?style=for-the-badge&labelColor=555555&logo=data:image/svg+xml;base64,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" height="20">][doc-url]
[<img alt="crates.io" src="https://img.shields.io/crates/v/hick-embassy?style=for-the-badge&logo=data:image/svg+xml;base64,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" height="22">][crates-url]
[<img alt="crates.io" src="https://img.shields.io/crates/d/hick-embassy?color=critical&logo=data:image/svg+xml;base64,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&style=for-the-badge" height="22">][crates-url]
<img alt="license" src="https://img.shields.io/badge/License-Apache%202.0/MIT-blue.svg?style=for-the-badge&fontColor=white&logoColor=f5c076&logo=data:image/svg+xml;base64,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" height="22">
</div>
## Introduction
`hick-embassy` is the [embassy] async driver for the [`hick`] mDNS family. It
builds on the [`hick-smoltcp`] engine, supplying an [`embassy-net`] `UdpIo`
transport, the [`embassy-time`] clock bridge, and an async driver future you
spawn as an embassy task.
For the std / hosted runtimes (`tokio`, `smol`, `compio`), use [`hick-reactor`],
[`hick-compio`], or the [`hick`] facade instead.
## Installation
```toml
[dependencies]
hick-embassy = "0.1"
```
## Example
Share one [`MdnsState`](https://docs.rs/hick-embassy/latest/hick_embassy/struct.MdnsState.html)
between the driver task and the application (via `Rc` or a `&'static`
`StaticCell`):
```rust,ignore
use hick_embassy::MdnsState;
use mdns_proto::{EndpointConfig, Name, ServiceRecords, ServiceSpec};
let state: &'static MdnsState<_> =
make_static!(MdnsState::new(EndpointConfig::new(), rng));
// Advertise a service.
let mut records = ServiceRecords::new(
Name::try_from_str("_http._tcp.local.").unwrap(),
Name::try_from_str("My Device._http._tcp.local.").unwrap(),
Name::try_from_str("mydevice.local.").unwrap(),
80,
120,
);
records.add_a(my_ipv4_addr);
state.register_service(ServiceSpec::new(records)).unwrap();
// Bind v4/v6 sockets to :5353 and join the mDNS group(s), then spawn the driver task
// (it enforces the RFC 6762 §11 egress hop-limit 255 itself — pass sockets by &mut):
spawner.must_spawn(mdns_task(state, v4_socket, v6_socket, scratch));
#[embassy_executor::task]
async fn mdns_task(
state: &'static MdnsState<MyRng>,
v4: &'static mut UdpSocket<'static>,
v6: &'static mut UdpSocket<'static>,
scratch: &'static mut [u8],
) -> ! {
state.run(Some(v4), Some(v6), scratch).await
}
```
## Feature flags
| Feature | Description |
|---------|-------------|
| `atomic` *(default)* | The native-atomic alloc tier: `SmolStr` names + `Bytes` rdata. Needs pointer-width atomics. |
| `no-atomic` | For cores **without** native atomic CAS (Cortex-M0+ / thumbv6m / RP2040): swaps the refcounted Name / rdata onto `portable-atomic`'s `Arc` (clone via a `critical-section` impl your binary provides), keeping the alloc-backed pools. Build with `--no-default-features --features no-atomic`. |
| `tracing` | Forward structured `tracing` events from `mdns-proto` and `hick-smoltcp` (no-op on bare-metal without a subscriber). |
| `stats` | Enable `no_std`-safe atomic counters; read a snapshot via `state.stats()`. Implies `atomic`. |
| `defmt` | Emit `defmt` log events — the idiomatic choice for embassy bare-metal targets. |
## Observability
For embassy targets the recommended logging path is `defmt` combined with
`stats`:
```toml
hick-embassy = { version = "0.1", features = ["defmt", "stats"] }
```
Enable `defmt` to have the driver emit structured log events through the
`defmt` framework alongside embassy's own logging.
Enable `stats` and call `state.stats()` to obtain a
`hick_trace::stats::StatsSnapshot`:
```rust,ignore
let snap = state.stats();
// snap.packets_rx, snap.services_active, snap.cache_size, etc.
```
The `tracing` feature is available but is a no-op on bare-metal targets that
do not set up a `tracing` subscriber.
The `metrics` feature (bridging counters to the [`metrics`] facade) requires
`std` and is not available on embassy bare-metal targets. Use `stats` + `defmt`
instead for observability on embedded.
## Design
- **Single-executor `!Send`**: no `Arc`, no atomics. `MdnsState` holds the engine
behind a `RefCell` plus an `embassy_sync` wake `Signal`; every handle method
takes `&self`, and a borrow never spans an `.await`.
- **Dual v4/v6 stack**: the driver pumps a `DualUdp` over the present sockets and
wakes on a `select` of either socket's RX-readiness, the next protocol
deadline, or a handle signalling new work.
- Builds entirely on the [`hick-smoltcp`] engine — embassy supplies only the
transport, clock, and the task wrapper.
## The hick family
[`hick`] (facade) · [`mdns-proto`] (Sans-I/O core) · [`hick-udp`] (UDP) ·
[`hick-reactor`] (tokio / smol driver) · [`hick-compio`] (compio driver) ·
[`hick-smoltcp`] (smoltcp engine) · **`hick-embassy`** (this crate).
## License
`hick-embassy` is under the terms of both the MIT license and the Apache License
(Version 2.0).
See [LICENSE-APACHE](LICENSE-APACHE), [LICENSE-MIT](LICENSE-MIT) for details.
Copyright (c) 2025 Al Liu.
[`hick`]: https://crates.io/crates/hick
[`mdns-proto`]: https://crates.io/crates/mdns-proto
[`hick-udp`]: https://crates.io/crates/hick-udp
[`hick-reactor`]: https://crates.io/crates/hick-reactor
[`hick-compio`]: https://crates.io/crates/hick-compio
[`hick-smoltcp`]: https://crates.io/crates/hick-smoltcp
[embassy]: https://embassy.dev
[`embassy-net`]: https://crates.io/crates/embassy-net
[`embassy-time`]: https://crates.io/crates/embassy-time
[`metrics`]: https://crates.io/crates/metrics
[Github-url]: https://github.com/al8n/hick/
[CI-url]: https://github.com/al8n/hick/actions/workflows/ci.yml
[codecov-url]: https://app.codecov.io/gh/al8n/hick/
[doc-url]: https://docs.rs/hick-embassy
[crates-url]: https://crates.io/crates/hick-embassy