# go-dns — Project Specification

## Overview

**go-dns** is a Go library for authoritative DNS operations against **BIND** (and compatible servers):

- **Dynamic updates** — same semantics as `nsupdate` ([RFC 2136](https://www.rfc-editor.org/rfc/rfc2136))
- **Zone transfer** — full **AXFR** only ([RFC 5936](https://www.rfc-editor.org/rfc/rfc5936)); IXFR is backlog
- **TSIG authentication** — callers supply existing shared keys; key generation is out of scope

Callers perform updates and full zone reads in Go with typed **zone data structures** and **typed RR builders** instead of shelling out to `nsupdate` or `dig axfr`.

## Module metadata

| Item | Value |
|------|-------|
| Module path | `gitea.neitzel.de/konrad/go-dns` |
| Go version | 1.26.4 (workspace `go.work`) |
| Public package | **`godns`** (`package godns` at module root) |
| Git remote (implementation) | `ssh://git@gitea.neitzel.de:2222/konrad/go-dns.git` |

## Target environment

| Item | Value |
|------|-------|
| Nameserver | BIND 9.x (primary reference) |
| Protocols | RFC 2136 UPDATE (UDP + **automatic TCP fallback**); **AXFR over TCP** |
| Authentication | TSIG (RFC 2845 / RFC 8945) — required for documented happy path |
| Domain names | **ASCII only** in v1 (no IDNA) |
| Out of scope (initially) | IXFR, full DNS server, recursive resolver, TSIG key generation, IDNA |

## Supported operation surface

The authoritative list lives in change **00001-setup-project** ([spec.md](changes/00001-setup-project/spec.md)). Summary:

1. **Session & TSIG key** — server, zone, transport, existing key (name, algorithm, secret)
2. **Dynamic update** — add, delete, prerequisites, batch UPDATE; typed RR builders
3. **Zone transfer** — **AXFR** only; parse stream into zone data
4. **Zone data model** — `Record`, `RRSet`, `Zone`, `UpdateResult`, `TransferResult`
5. **BIND guide** — [bind-tsig-configuration.md](bind-tsig-configuration.md) (`allow-update` + `allow-transfer` for a TSIG key)

Future work: [backlog.md](backlog.md) (includes **IXFR**).

## API style

- **Typed builders** per RR type (e.g. A, AAAA, MX, SRV) — not a generic `(type, rdata string)` API
- Exact method names follow in subsequent changes after the catalog is agreed

## Zone data model (logical)

| Type | Purpose |
|------|---------|
| **Record** | Single RR: owner, class, type, TTL, typed rdata |
| **RRSet** | Group of RRs with same owner/class/type |
| **Zone** | Origin + full record set + SOA/serial (complete zone in memory) |
| **UpdateResult** | UPDATE response status |
| **TransferResult** | AXFR result + populated `Zone` + serial metadata |

## BIND configuration

Operators configure BIND so a TSIG key may **update** and **transfer** a zone (`allow-update`, `allow-transfer`). Step-by-step instructions, security notes, and a minimal `named.conf` example:

**[docs/bind-tsig-configuration.md](bind-tsig-configuration.md)**

## Change workflow

Features are delivered through documented changes under `docs/changes/<Number>-<short-description>/` (spec → plan → implement → verify → changes). The product backlog lives at [backlog.md](backlog.md).

## Tests

| Command | Purpose |
|---------|---------|
| `go test ./...` | Unit tests (encoding, parsing, zone model, typed builders) |
| `go test -tags=integration ./...` | **BIND testcontainer** (Docker required) |

Integration tests use testcontainers-go with a BIND image per workspace `integration-testing.mdc`.

## Package layout (planned)

```
package godns          # public API at module root
internal/              # RFC 2136, AXFR, TSIG, wire format
docs/                  # Project docs incl. bind-tsig-configuration.md, backlog.md
```

Layout details are finalized in the setup implementation plan.