presence-switch

A Discord Rich Presence IPC proxy that multiplexes RPC messages across multiple Discord instances.

What it does

presence-switch sits between Discord RPC client applications (games, media players, etc.) and running Discord instances. It binds the first available discord-ipc-{0..9} socket (preferring discord-ipc-0) and relays all incoming RPC messages to every other existing Discord IPC socket.

This means a single RPC client can broadcast its presence to multiple Discord clients simultaneously.

How it works

graph LR
    A["RPC Client<br/>(e.g. game)"] --> B["presence-switch<br/>(discord-ipc-0)"]
    B --> C["Discord #1"]
    B --> D["Discord #2"]
    B --> E["Discord #N"]

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1. The switch claims an available discord-ipc-* socket name
2. RPC clients connect to the switch thinking it's Discord
3. The switch relays messages to all real Discord instances on other sockets

The IPC binary protocol uses a simple format: 4-byte LE opcode + 4-byte LE length + UTF-8 JSON payload. The switch processes handshake, ping, and close opcodes directly, and forwards all other opcodes (frame, pong) to Discord.

Requirements

• Rust (edition 2024)
• One or more running Discord instances

Building

cargo build --release

Installing

Tagged releases publish .rpm and .msi builds to the Releases page. For unreleased changes, the Package workflow also produces dev artifacts on every push to main and every PR — download them from the workflow run's Artifacts section.

To build packages locally:

scripts/package.sh rpm   # → target/generate-rpm/presence-switch-*.rpm
scripts/package.sh msi   # → target/wix/presence-switch-*.msi (cross-compiled from Linux)
scripts/package.sh all

See scripts/package.sh --help for the toolchain requirements.

Linux (any RPM-based distro with systemd)

sudo dnf install ./presence-switch-*.rpm   # Fedora, RHEL, CentOS, Rocky, Alma
sudo zypper install ./presence-switch-*.rpm   # openSUSE
systemctl --user daemon-reload
systemctl --user enable --now presence-switch

The package installs a per-user systemd unit at /usr/lib/systemd/user/presence-switch.service. View logs with journalctl --user -u presence-switch. CI builds the RPM against Ubuntu 24.04's glibc (2.39+), so the target distro needs glibc ≥ 2.39 — that covers Fedora 41+, RHEL 10+, recent openSUSE Tumbleweed, and similar.

Windows

Double-click the .msi to install per-user (no admin prompt). The installer adds an entry under HKCU\Software\Microsoft\Windows\CurrentVersion\Run so presence-switch launches at every logon — inspect or disable it via Task Manager → Startup apps. Uninstall via Settings → Apps & features.

Usage

1. Close Discord or ensure discord-ipc-0 is not taken
2. Run presence-switch:

   cargo run --release

3. Start your Discord instances — they will claim discord-ipc-1, discord-ipc-2, etc.
4. Launch your RPC-enabled application — it connects to presence-switch on discord-ipc-0, which relays to all Discord instances

For best results, start presence-switch before any Discord instances so it can claim discord-ipc-0, which is what most RPC clients connect to by default.

Press Ctrl+C to shut down gracefully.

Platform support

Platform	IPC mechanism
Linux	Unix domain sockets
macOS	Unix domain sockets
Windows	Named pipes

Platform-specific implementations are selected at compile time via #[cfg].

Project structure

src/
├── main.rs
├── switch/         # IPC server — accepts RPC client connections
│   └── ipc/
│       ├── mod.rs      # Server and Client logic
│       ├── unix.rs     # Unix domain socket listener
│       └── windows.rs  # Named pipe listener
└── discord/        # IPC client — connects to real Discord instances
    ├── api.rs          # Discord REST API for app metadata (cached)
    └── ipc/
        ├── mod.rs      # Client, protocol types, socket discovery
        ├── unix.rs     # Unix domain socket connection
        └── windows.rs  # Named pipe connection

Releasing

To cut a new release:

1. Bump version in Cargo.toml (and run cargo update -w so Cargo.lock matches).
2. Commit the bump and merge to main.
3. Tag the commit on main matching the new version, e.g.:

   git tag v0.2.0
   git push origin v0.2.0

4. The Package workflow runs on the tag, validates that the tag matches Cargo.toml, builds the .rpm and .msi, and publishes a GitHub Release with both attached and auto-generated notes from the commits since the previous release.

If the tag version doesn't match Cargo.toml's version field, both build jobs fail loudly before doing any work.

License

MIT © Kramer Campbell