ipp-printer-app

Pure-Rust IPP Everywhere framework for building CUPS-driverless printer applications — the modern replacement for the PPD-driven CUPS filter+backend model.

The framework speaks IPP over HTTP on /ipp/print/<name>, runs the job state machine, tracks printer-state-reasons, and (optionally) advertises itself over mDNS. You supply two things:

• a [DeviceBackend] — how to enumerate physical devices and poll their status, and
• a [RasterDriver] — how to turn a PWG-raster page into device bytes.

That's enough to land in CUPS via lpadmin -m everywhere and have cups-browsed pick the printer up automatically.

Quick start

cargo add ipp-printer-app

Minimal server (no real device, just shows the wiring):

use std::sync::Arc;
use ipp_printer_app::{
    default_state_path, DeviceBackend, PrinterConfig, PrinterRecord,
    PrinterRegistry, Server, ServerOptions,
};
use parking_lot::RwLock;

struct MyBackend;
impl DeviceBackend for MyBackend {
    fn list(&self, emit: &mut dyn FnMut(&str, &str, &str) -> bool) {
        let _ = emit("My Printer", "mydev://demo", "MFG:Demo;MDL:Test;");
    }
    fn driver_for_device(&self, _: &str, _: &str) -> Option<String> {
        Some("my_driver".into())
    }
}

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let registry: PrinterRegistry = Arc::new(RwLock::new(Vec::new()));
    let state_path = default_state_path("my-printer-app");
    let backend = Arc::new(MyBackend);

    Server::bootstrap_printers(&registry, backend.as_ref(), &state_path,
        |name, driver, uri, device_id| Some(PrinterConfig {
            name: name.into(),
            driver_name: driver.into(),
            make_and_model: "My Printer".into(),
            device_id: device_id.into(),
            device_uri: uri.into(),
            dpi: 203,
            printhead_width_dots: 384,
            media_names: vec!["oe_30x20mm_30x20mm".into()],
            media_sizes: vec![[3000, 2000]],
            darkness: 50,
        }),
    );

    Server::run(ServerOptions {
        host: "127.0.0.1".into(),
        port: 8631,
        printers: registry,
        device_backend: backend,
        print_job: Arc::new(|_ctx, _raster, _copies| Ok(())),
        state_path,
    }).await
}

See examples/minimal_server.rs for a runnable version.

What's in the box

Concern	What you get
IPP wire format	ipp crate (parser + types)
HTTP server	axum 0.8 on tokio
Job lifecycle	JobRegistry with monotonic ids, Get-Jobs / Get-Job-Attributes / Cancel-Job
Live status	Background poll loop calling DeviceBackend::poll_status, configurable cadence (IPP_PRINTER_APP_POLL_SECS, default 30 s)
Discovery	mDNS _ipp._tcp.local. via mdns-sd, default-on mdns feature
State	JSON registry persisted at $XDG_STATE_HOME/<app-id>.state.json
Raster format	PWG raster + legacy CUPS raster v1/v2 via print_raster

What's not here:

• A device-side raster transform (dither, column-major, compression) — that's RasterDriver territory.
• A real-time job spooler with on-disk job persistence (in-memory only).
• HTTPS / IPP-over-TLS.
• URF format support (only PWG raster + CUPS raster).
• Color / multi-bit raster — the surface is 1bpp monochrome by default, drivers can extend.

Features

Feature	Default	What it pulls in
mdns	✓	mdns-sd (~200 KB) for _ipp._tcp.local. advertising

For embedded targets without mDNS, build with --no-default-features to drop ~200 KB of dependencies.

CUPS integration

Once a printer application is running on localhost:8631:

sudo lpadmin -p MY_PRINTER -E -v ipp://localhost:8631/ipp/print/NAME -m everywhere

If you have cups-browsed running and built the framework with the default mdns feature, the queue auto-appears within ~10 seconds and no manual lpadmin is needed.

Reference consumer

supvan-cups (Supvan label printers) is the reference real-world consumer. The full chain there: supvan-app (binary) → supvan-proto (Bluetooth / USB HID transport) → ipp-printer-app (this crate) → axum / ipp / print_raster.

MSRV

Rust 1.74.

License

MIT.