# rustbot

A small, modular IRC bot in Rust — **zero dependencies**, with its own IRC
protocol layer built to the [modern IRC client spec](https://modern.ircdocs.horse/).

## Structure

| File          | Layer            | Responsibility                                            |
|---------------|------------------|-----------------------------------------------------------|
| `src/irc.rs`  | protocol + I/O   | Parse/serialize IRC messages (incl. IRCv3 tags), TCP transport |
| `src/bot.rs`  | behavior         | Registration, event loop, command handling                |
| `src/main.rs` | wiring           | Config from env vars, connect/reconnect supervisor        |

The layers are deliberately separable: `irc.rs` knows nothing about the bot, and
`bot.rs` knows nothing about how the process is launched.

## Build & run

```sh
cargo build            # or: cargo build --release
cargo test             # unit tests for the message parser
cargo run
```

## Configuration

Settings are layered, each overriding the previous:

1. **Built-in defaults** (`Config::default()` in `src/bot.rs`)
2. **A config file** — `key = value`, see [`rustbot.conf`](rustbot.conf)
3. **Environment variables** — handy for one-off overrides

The config file is found via: the **first CLI argument**, else `RUSTBOT_CONFIG`,
else `./rustbot.conf` if present.

```sh
cargo run                       # uses ./rustbot.conf
cargo run -- /etc/rustbot.conf  # explicit path
RUSTBOT_CONFIG=/etc/rustbot.conf cargo run
```

Config file keys: `server`, `port`, `tls`, `nick`, `user`, `realname`,
`channels` (comma/space-separated), `prefix`, `password`, `sasl_user`, `sasl_pass`.
Whole-line `#`/`;` comments only — inline comments would clash with channel `#`s.

Environment overrides: `IRC_SERVER`, `IRC_PORT`, `IRC_TLS`, `IRC_NICK`,
`IRC_REALNAME`, `IRC_CHANNELS`, `IRC_PREFIX`, `IRC_PASSWORD`,
`IRC_SASL_USER`, `IRC_SASL_PASS`.

```sh
IRC_NICK=mybot IRC_CHANNELS='#test' cargo run   # override the file for one run
```

> If you put a real `password` in `rustbot.conf`, add it to `.gitignore` so the
> secret isn't committed.

## Built-in commands

With the default `!` prefix:

- `!ping` → `pong`
- `!echo <text>` → echoes text back
- `!hello` → greets the sender
- `!help` → lists commands

Add your own in `Bot::handle_command` in `src/bot.rs`.

## Deployment (systemd)

Runs as a system service (`User=debian`), auto-restarts on crash, and starts on
boot. The unit is kept in the repo as [`rustbot.service`](rustbot.service).

```sh
cargo build --release
sudo cp rustbot.service /etc/systemd/system/rustbot.service
sudo systemctl daemon-reload
sudo systemctl enable --now rustbot        # start now + on boot

systemctl status rustbot                   # health
journalctl -u rustbot -f                    # live logs (<< in, >> out)
sudo systemctl restart rustbot             # after a rebuild
```

One-off overrides without touching `rustbot.conf`: put `IRC_*` lines in
`/etc/default/rustbot` (env wins over the config file), then restart.

## IRCv3

The bot negotiates capabilities (`CAP LS 302` → `CAP REQ` → `CAP END`) and
enables everything useful the server offers: `message-tags`, `server-time`,
`batch`, `echo-message`, `account-tag`, `extended-join`, `multi-prefix`,
`away-notify`, `chghost`, `setname`, `userhost-in-names`, `cap-notify`,
`labeled-response`.

Two of these do real work:

- **`server-time` + `batch`** let the bot recognise **replayed history**. On
  join, InspIRCd replays recent channel lines (wrapped in a `chathistory`
  batch). Without this the bot re-answered old commands on every reconnect;
  now such messages are ignored (see `Bot::is_historical`).
- **`sasl`** (PLAIN) authenticates to services during negotiation. Set
  `sasl_user`/`sasl_pass` in the config (or `IRC_SASL_USER`/`IRC_SASL_PASS`).
  base64 is hand-rolled, so this stays dependency-free.

## TLS

Set `tls = true` and the port defaults to 6697. The transport wraps the socket
with `native-tls`, which verifies certificates against the **system OpenSSL
trust store** — so TLS security fixes arrive via OS updates rather than a
vendored crypto crate. Plaintext still works with `tls = false` / `port = 6667`.

Plain TCP and TLS share one code path: `Connection` holds a single
`Box<dyn Read + Write>`, since the single-threaded event loop never needs the
old read/write socket split (which TLS can't do anyway).

## Roadmap / natural next steps

- **Read timeout + client-sent PING** to detect dead connections faster.
- **STARTTLS** (the `tls` cap) for networks without a dedicated TLS port.
- Split commands into a registry/trait once there are many of them.