# catalog-zone-gen

Generate RFC 9432 DNS catalog zone files from a declarative input file.

Given a list of zones with their catalog assignments and optional properties,
this tool produces one BIND-format zone file per catalog. Output is
deterministic: re-running with unchanged input produces unchanged output (no
serial bump, no file write).

## Installation

```
go install catalog-zone-gen@latest
```

Or build from source:

```
go build -o catalog-zone-gen .
```

## Usage

```
catalog-zone-gen [--config path] [--output-dir path] <input-file>
```

**Flags:**

- `--config` — path to YAML config file (default: `catz.yaml` next to the input file)
- `--output-dir` — directory for output zone files (default: same directory as the input file)

## Configuration File

The config file (default `catz.yaml`) defines catalog zone names and SOA parameters.

```yaml
catalogs:
  catalog1:
    zone: catalog1.example.com.
  catalog2:
    zone: catalog2.example.com.

soa:
  mname: ns1.example.com.
  rname: hostmaster.example.com.
```

### Fields

| Field | Required | Description |
|-------|----------|-------------|
| `catalogs` | yes | Map of catalog names to their zone FQDNs. Names are used as references in the input file. |
| `catalogs.<name>.zone` | yes | The FQDN of the catalog zone (trailing dot optional, will be normalized). |
| `soa.mname` | yes | Primary nameserver for the SOA record. |
| `soa.rname` | yes | Responsible person email (in DNS format: `hostmaster.example.com.`). |

SOA timing values are hardcoded: refresh=900, retry=600, expire=2147483646, minimum=0.
The NS record is hardcoded to `invalid.` per RFC 9432.

## Input File Format

Whitespace and comma delimited. Lines starting with `#` are comments.
Blank lines are ignored.

```
<zone-name>  <catalog>[, <catalog>...]  [, group=<value>]  [, coo=<fqdn>]
```

### Fields

| Position | Format | Description |
|----------|--------|-------------|
| First token | FQDN | Zone name (trailing dot optional, normalized internally). |
| Bare names | identifier | Catalog assignments — must match a key in the config `catalogs` map. At least one required. |
| `group=<value>` | key=value | RFC 9432 group property. Tells consumers to apply shared configuration to grouped zones. |
| `coo=<fqdn>` | key=value | RFC 9432 change-of-ownership property. Points to the old catalog zone during migration. |

A zone can appear in multiple catalogs (for distributing to different server groups).

### Example

```
# Production zones
zone.example.org    catalog1, catalog2
zone.example.com    catalog2, coo=old-catalog.example.com.
test.example.net    catalog1, group=internal
app.example.org     catalog1, group=external, coo=migrated.example.com.
```

Whitespace and comma placement is flexible. These are all equivalent:

```
zone.example.org  catalog1,catalog2
zone.example.org  catalog1 , catalog2
zone.example.org  catalog1, catalog2
```

## Output

One BIND-format zone file per catalog, written to the output directory.

**Filename:** `<catalog-zone-fqdn>.zone` (e.g., `catalog1.example.com.zone`)

**Example output:**

```
catalog1.example.com.	0	IN	SOA	ns1.example.com. hostmaster.example.com. 2026030201 900 600 2147483646 0
catalog1.example.com.	0	IN	NS	invalid.
version.catalog1.example.com.	0	IN	TXT	"2"
grfen8g.zones.catalog1.example.com.	0	IN	PTR	app.example.org.
group.grfen8g.zones.catalog1.example.com.	0	IN	TXT	"external"
coo.grfen8g.zones.catalog1.example.com.	0	IN	PTR	migrated.example.com.
2qvgcfg.zones.catalog1.example.com.	0	IN	PTR	test.example.net.
group.2qvgcfg.zones.catalog1.example.com.	0	IN	TXT	"internal"
1860l9o.zones.catalog1.example.com.	0	IN	PTR	zone.example.org.
```

### Record order

1. SOA record
2. NS record (`invalid.`)
3. Version TXT record (`"2"`)
4. Member zones sorted alphabetically by zone name, each with:
   - PTR record (member zone)
   - Group TXT record (if `group=` set)
   - COO PTR record (if `coo=` set)

All records use TTL 0 and class IN. Fully-qualified owner names; no `$ORIGIN` or `$TTL` directives.

### Member zone hashing

Member zone labels are generated by FNV-1a 32-bit hashing the normalized zone
name, then encoding as lowercase base32hex without padding. This produces
compact labels like `grfen8g`.

Changing tools will likely produce different hash labels, which is intentional
per RFC 9432 Section 5.4 — it triggers a reconfig event on consumers.

### SOA serial

Format: `YYYYMMDDNN` where NN is a sequence number (01-99).

- New zone files start at `YYYYMMDD01`.
- On subsequent runs, the tool generates output with the existing serial and
  compares bytes. If unchanged, no write occurs.
- If content differs, the serial is incremented (same date bumps NN; new date
  resets to `YYYYMMDD01`).
- If NN reaches 99 on the same date: the tool errors.

## Validation

The tool validates input and reports errors with file location:

```
error: zones.txt:3: unknown catalog "bogus"
error: zones.txt:5: zone example.com. already assigned to catalog "catalog1" at line 2
```

**Checked conditions:**

- Unknown catalog name (not in config) — error
- Same zone assigned to the same catalog more than once — error
- Hash collision (two zone names produce the same hash within a catalog) — error
- Missing required config fields — error
- Unknown properties (anything other than `group` and `coo`) — error