nidus/README.md

# DAV Server

A self-hosted **CalDAV**, **CardDAV**, and **WebDAV** server written in Go.

## Features

| Protocol | Use case |
|----------|----------|
| CalDAV   | Calendars — sync with Apple Calendar, Thunderbird, GNOME Calendar, … |
| CardDAV  | Contacts — sync with Apple Contacts, GNOME Contacts, … |
| WebDAV   | General file access via Finder, Windows Explorer, Nautilus, … |

- HTTP Basic Auth with **bcrypt** password storage
- Per-user isolated collections
- **Calendar/address book sharing** — grant other users read or write
  access to your calendars/address books
- **Web UI** — a small dashboard (login, manage shares) at `/ui/`, built
  with templ + Tailwind + htmx
- Auto-discovery via `/.well-known/caldav` and `/.well-known/carddav`
- Optional **TLS** (or use a reverse proxy)
- Structured logging (text or JSON)
- Graceful shutdown
- Docker & Docker Compose support

## Quick start

### 1. Install dependencies

```bash
go mod tidy
```

### 2. Generate password hashes

```bash
go run ./tools/hashpwd mysecretpassword
# Outputs: $2b$12$...
```

### 3. Create your `config.yaml`

Copy the example config and edit it — `config.yaml` is git-ignored so your
real credentials/domain never get committed:

```bash
cp config.example.yaml config.yaml
```

Replace the placeholder hashes with your real bcrypt hashes:

```yaml
users:
  alice:
    password: "$2b$12$<hash generated above>"
    display_name: "Alice Smith"
    email: "alice@example.com"
    calendars:
      - personal
      - work
    address_books:
      - contacts
```

### 4. Run the server

```bash
make run
# or
go run ./cmd/server -config config.yaml
```

The server starts at **http://localhost:8080**.

---

## Docker

```bash
# Build and start
docker compose up --build

# Or build manually
docker build -t davserver .
docker run -p 8080:8080 \
  -v ./config.yaml:/app/config.yaml:ro \
  -v dav-data:/app/data \
  davserver
```

---

## Client configuration

### Apple Calendar / Contacts (macOS / iOS)

1. Go to **Settings → Calendar → Accounts → Add Account → Other → Add CalDAV Account**
2. Enter:
   - **Server**: `http://yourserver:8080`
   - **Username**: `alice`
   - **Password**: your plaintext password
3. The app will auto-discover calendars at `/cal/`.

Same flow for **CardDAV** with Contacts app.

### Thunderbird

1. Install the **TbSync** add-on + **CalDAV & CardDAV** provider
2. Add a new account and point it at `http://yourserver:8080/.well-known/caldav`

### GNOME Calendar / Evolution

Use the GNOME Online Accounts panel:
- **Server**: `http://yourserver:8080`
- Check *CalDAV* / *CardDAV* as appropriate

---

## API endpoints

| Path | Description |
|------|-------------|
| `/.well-known/caldav` | Redirects to `/cal/` |
| `/.well-known/carddav` | Redirects to `/card/` |
| `/cal/` | CalDAV principal (same URL for every user; resolved via Basic Auth) |
| `/cal/home/` | Calendar home-set (lists the user's calendars) |
| `/cal/home/<calendar>/` | Calendar collection |
| `/card/` | CardDAV principal (same URL for every user; resolved via Basic Auth) |
| `/card/home/` | Address book home-set (lists the user's address books) |
| `/card/home/<book>/` | Address book collection |
| `/files/` | WebDAV file storage (same URL for every user; resolved via Basic Auth) |
| `/healthz` | Health check (unauthenticated) |

> **Note:** the `home` segment is a fixed literal (not a username or real
> resource) — it exists only to give the calendar/address-book home-set the
> path depth that the underlying CalDAV/CardDAV library expects when
> classifying resources by URL. Clients should never need to construct
> these URLs by hand; they're discovered automatically via
> `.well-known` + `current-user-principal` + `calendar-home-set` /
> `addressbook-home-set` properties.

---

## Sharing calendars and address books

A user can grant another user read or write access to one of their own
calendars or address books. Shared resources show up automatically in the
grantee's own home-set alongside their own calendars — no separate account
or extra client configuration needed.

Sharing grants are stored in a small SQLite database at
`<data_dir>/nidus.db` (not in `config.yaml`) and can be managed either via
the `nidusctl` CLI or the web UI's dashboard (see below):

```bash
# Give bob write access to alice's "work" calendar
go run ./tools/nidusctl -config config.yaml calendar share alice work bob write

# List everyone alice's "work" calendar is shared with
go run ./tools/nidusctl -config config.yaml calendar shares alice work

# Revoke access
go run ./tools/nidusctl -config config.yaml calendar unshare alice work bob

# Address books work the same way, using "addressbook" instead of "calendar"
go run ./tools/nidusctl -config config.yaml addressbook share alice contacts bob read
```

Or via `make`: `make nidusctl ARGS="calendar share alice work bob write"`.

A calendar that `alice` shares with `bob` appears in bob's calendar
home-set as `/cal/home/alice~work/` (i.e. `<owner>~<calendar name>`) — the
data itself still physically lives under alice's own storage; nothing is
copied. The same scheme applies to address books under `/card/home/`.
Read-only shares reject any write (PUT/DELETE) with `403 Forbidden`.

---

## Web UI

A small server-rendered dashboard is served at `/ui/` (separate from the
DAV endpoints, which stay on HTTP Basic Auth):

- **Login** (`/ui/login`) — cookie-based session, stored server-side in
  `nidus.db` (`web_sessions` table), independent of DAV Basic Auth.
- **Dashboard** (`/ui/`) — lists your own calendars/address books, who
  they're shared with, and any resources other users have shared with you.
- **Share management** — add/remove shares directly from the dashboard
  (same effect as `nidusctl`); updates happen in place via
  [htmx](https://htmx.org/) without a full page reload.
- **Logout** (`/ui/logout`).

Implementation: [templ](https://templ.guide/) for type-safe Go HTML
templates, [Tailwind CSS v4](https://tailwindcss.com/) for styling, and
htmx for the sprinkles of dynamic behavior (form submission via
POST/DELETE, partial page swaps) — no separate JS build/framework needed.
The compiled CSS and the htmx bundle are embedded into the Go binary
(`web/staticassets.go`), so no Node.js is required at runtime, only when
you change styles or templates during development:

```bash
make web-deps   # once, installs the Tailwind CLI (needs Node.js/npm)
make web-css    # regenerate templ code + rebuild web/static/app.css
```

---

## TLS / Reverse proxy

### Self-signed certificate (development)

```bash
openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365 -nodes
```

Update `config.yaml`:

```yaml
tls:
  enabled: true
  cert_file: cert.pem
  key_file:  key.pem
```

### Caddy reverse proxy (recommended for production)

```
dav.example.com {
    reverse_proxy localhost:8080
}
```

---

## Configuration reference

```yaml
server:
  host: "0.0.0.0"
  port: 8080
  base_url: "https://dav.example.com"   # used in DAV responses

auth:
  realm: "My DAV Server"

storage:
  data_dir: "./data"   # all user data lives here

logging:
  level: "info"    # debug | info | warn | error
  format: "text"   # text | json

tls:
  enabled: false
  cert_file: ""
  key_file:  ""

users:
  <username>:
    password: "<bcrypt hash>"
    display_name: "Full Name"
    email: "user@example.com"
    calendars:       # pre-created calendar names
      - personal
    address_books:   # pre-created address book names
      - contacts
```

---

## Project layout

```
caldav-server/
├── cmd/server/          # main entrypoint
├── internal/
│   ├── auth/            # HTTP Basic Auth middleware (DAV endpoints)
│   ├── caldav/          # CalDAV backend
│   ├── carddav/         # CardDAV backend
│   ├── config/          # YAML config loader
│   ├── db/              # SQLite store (shares, web UI sessions)
│   ├── store/           # filesystem storage layer
│   ├── web/             # web UI (cookie sessions, dashboard, share mgmt)
│   │   └── templates/   # templ templates (+ generated *_templ.go)
│   └── webdav/          # WebDAV file handler
├── tools/hashpwd/       # bcrypt password hasher CLI
├── tools/nidusctl/      # sharing-grant admin CLI
├── web/                 # front-end assets: Tailwind input/config, static/
│   └── static/          # compiled app.css + htmx.min.js (embedded into the binary)
├── config.example.yaml  # sample configuration (copy to config.yaml)
├── Dockerfile
├── docker-compose.yaml
└── Makefile
```

---

## Running tests

```bash
make test
# or
go test ./... -race
```

---

## Dependencies

| Package | Purpose |
|---------|---------|
| `github.com/emersion/go-webdav` | WebDAV/CalDAV/CardDAV protocol layer |
| `github.com/emersion/go-ical`   | iCalendar parsing/serialisation |
| `github.com/emersion/go-vcard`  | vCard parsing/serialisation |
| `golang.org/x/crypto`           | bcrypt |
| `golang.org/x/net`              | `golang.org/x/net/webdav` |
| `gopkg.in/yaml.v3`              | YAML config parsing |
| `modernc.org/sqlite`            | Pure-Go SQLite driver (shares, web UI sessions) |
| `github.com/a-h/templ`          | Type-safe Go HTML templates (web UI) |

Front-end (dev-only, not required at runtime — see [Web UI](#web-ui)):

| Tool | Purpose |
|------|---------|
| Tailwind CSS v4 (`web/package.json`) | Utility-first CSS, compiled to `web/static/app.css` |
| [htmx](https://htmx.org/) (`web/static/htmx.min.js`, vendored) | Partial page updates without a JS framework |