TimekeeperEnforcement

# TimekeeperEnforcement

Local enforcement for the Timekeeper e107 plugin. Once a minute it looks for each
monitored student's games, asks the server how many play minutes are left
(`timer.php`), warns, and closes the game when there are none.

Needs Java 11 or newer. Run it as root (it stops other users' processes and shows
popups as them).

## Build

```bash
javac -d out src/au/pfip/*.java
jar --create --file TimekeeperEnforcement.jar --main-class au.pfip.Main -C out .
```

## Settings

The first of these that exists is used. Use `/etc/timekeeper.inf`, owned by root and
not writable by the students: a settings file they can edit defeats the monitoring.

1. `/etc/timekeeper.inf`
2. `~/timekeeper.inf`
3. `~/.config/timekeeper/timekeeper.inf`
4. `./timekeeper.inf`

If none exists, a new one is written to `~/.config/timekeeper/timekeeper.inf` with the
defaults below. It is Java XML properties format.

| Key | Default | Meaning |
|---|---|---|
| `UsersToMonitor` | *(empty, must be set)* | Comma separated accounts to watch, e.g. `alice,bob` |
| `TimekeeperActive` | `true` | `false` makes the program wait 10 minutes and exit |
| `ExemptNetwork` | *(empty = none)* | Network name where enforcement is off (checked at start-up only; anyone can name a hotspot after a network) |
| `OfflineChecksBeforeKill` | `5` | Failed server checks in a row before a game is closed (`1` = close at once) |
| `GamesRefreshMinutes` | `60` | How often the games list is fetched again |
| `GamesURL`, `PlaytimeURL` | the overlord URLs | Server endpoints |
| `LogFilePath` | home folder | Where `timekeeper.log` is written |
| `MatchWholeWords` | `true` | A game name must not run on into more letters or digits in the command line (`technic` no longer matches `technical-report.odt`). `false` = plain "contains" |
| `IgnoreCommandLines` | *(empty)* | Comma separated command line fragments that exempt a process, e.g. `--kiosk,-contentproc`. Anyone can add such a fragment to a command they start themselves |

## games.json

A JSON array of strings, or an object whose values are the names (keys are ignored).
Each name is looked for in the full command line (`ps -eo user,args`) of every process
the student owns, case-sensitively. Check what a game really looks like first:

```bash
ps -eo user,args | grep -i
```

- Use a name that appears in the command line, and is specific: `technic` also matched
`technical-report.odt` before whole-word matching.
- Wine/Proton games show up as their `.exe` name (`bf2.exe`). Native Steam games show up
as the binary (`hl2_linux`).
- Browsers listed here are closed like any other game, including a browser used for
Timekeeper's own questions. Use `IgnoreCommandLines` or a separate browser for those.
- It is a deny-list: a browser, launcher or game that isn't listed isn't enforced.

The games list is cached in `games.cache` next to the settings file and used when the
server can't be reached.

## systemd

```ini
[Unit]
Description=Timekeeper enforcement
After=network-online.target
Wants=network-online.target

[Service]
ExecStart=/usr/bin/java -jar /opt/timekeeper/TimekeeperEnforcement.jar
Restart=always
RestartSec=30
User=root

[Install]
WantedBy=multi-user.target
```

## Tests

`test/au/pfip/Harness.java` and `Harness2.java` run against a fake local server and
start and stop throwaway `sleep` processes owned by the current user:

```bash
javac -d out src/au/pfip/*.java test/au/pfip/*.java
java -cp out au.pfip.Harness
java -cp out au.pfip.Harness2
```