crowncrate-linux

The desktop side of the CrownOS phone bridge. A daemon that holds a persistent connection to a paired phone and carries clipboard, media, notification, call and OTP traffic.

Comparable to KDE Connect or Windows Phone Link.

Status: Early. It compiles and runs, but three of seven actions are implemented, there is no authentication, and the D-Bus service crownotify expects does not exist. See Other known gaps.

Protocol

Transport: TCP on 0.0.0.0:5252, one thread per connected device, held open for the life of the connection — "similar to websockets". UDP :5253 is bound for LAN discovery, though the discovery function is a stub.

Encoding: CBOR, streamed.

pub struct Message {
    pub client: Ipv4Addr,
    pub method: Actions,
    pub body: HashMap<String, String>,
}

#[repr(u8)]
pub enum Actions {
    CLIPBOARD, MEDIA, OPEN, OTPSYNC, MONITOR, VOLUME, SHUTDOWN,
}

src/communication/README.md says "one line json". That is out of date — the code uses CBOR, and serde_json is a declared but unused dependency.

Implemented actions:

Action	Implementation
SHUTDOWN	sh -c "shutdown now"
VOLUME	pactl set-sink-volume 0 {value}%
CLIPBOARD	prints the "type" field and nothing more

⚠ Security

There is no pairing, no authentication, and no encryption. Any peer that can reach port 5252 can send a SHUTDOWN message and power the machine off.

It was worse than that until recently: ActionManager::notify fanned every message out to every registered action, and ShutdownAction ignored message.method entirely — so any decodable frame, whatever its method, shut the machine down. notify now dispatches on the method, using the key the action table always had.

The crate builds and runs, so the remaining exposure is live. Do not run it on an untrusted network, and fix the missing pairing before anyone ships it.

See SECURITY.md.

The D-Bus interface it should expose

crownotify calls into this daemon for call handling:

pub const CROWNCRATE_SERVICE:   &str = "io.crownos.crowncrate";
pub const CROWNCRATE_PATH:      &str = "/io/crownos/crowncrate";
pub const CROWNCRATE_INTERFACE: &str = "io.crownos.crowncrate";
// methods: PickupCall, DeclineCall

This crate has no zbus dependency and no D-Bus code at all — the service does not exist. crownotify has a mock-based integration test for it, plus an ignored test that runs against a real daemon. Implementing it is well-scoped work.

Prerequisites

A Rust toolchain and nothing else. This is a headless daemon with no UI, and gtk4 — which it declared but never used, and which was by far the heaviest thing in its dependency graph — has been removed. The crate went from about 148 packages to 43.

If you re-add a UI later, the GTK4 4.10+ stack is:

sudo pacman -S --needed base-devel pkgconf gtk4 glib2 pango gdk-pixbuf2 graphene

Debian/Ubuntu equivalents: Prerequisites.

Ports 5252/tcp and 5253/udp must be reachable for the bridge to work.

Build

cargo build
cargo run      # binds TCP :5252

Rust 1.88+, pinned in rust-toolchain.toml. No CrownOS dependencies, so no dev overlay is needed.

Do not copy this repository's rustfmt.toml. It is the only one in the organization and it is a liability — an ~80-key dump of defaults containing edition = "2015" (the crate is edition 2024), required_version = "1.5.1" (rustfmt refuses to run on a mismatch), the deprecated fn_args_layout, and several nightly-only keys alongside unstable_features = false. Every other repo uses rustfmt defaults. Deleting it is a reasonable patch.

Tests

There are none — no unit tests, no integration tests, no examples. cargo test compiles the crate and reports zero tests. The CBOR Message round-trip and ActionManager::subscribe/unsubscribe are the obvious first targets.

Configuration

There is none. src/config/mod.rs holds a single constant — DEFAULT_LOGGING_FILE_PATH = "/var/log/crowncrate.log". The listen addresses, the ports and the pairing state are all hardcoded, and the crate does not depend on crownos-config.

Other known gaps

• The empty src/ui/mod.rs, src/lib.rs, src/predule.rs and src/config/mod.rs have been deleted, along with the unused gtk4, serde_json, bytes and anyhow dependencies. What remains of the dependency set is still older than the rest of the organization.
• src/discovery/mod.rs binds a socket and returns; it is never called.
• src/logging.rs mixes fn log(&mut self, ..) with receiver-less warn/debug/error in one trait; FileLogger is imported and unused; writeln! results are ignored.

The other halves

Repo	Role	State
crowncrate-android	Client	Android Studio template; no network permission
crowncrate-chrome	Browser client	No commits

The two halves have never communicated.

Contributing

See the organization-wide contribution guide. Default branch here is main.

License

Licensed under the MIT License.