Ryan Malloy
0f28127284
Major architectural pivot per the user's "RFC 2136 mechanism for the existing zonefiles, not a new in-memory thing" framing. The plugin no longer maintains its own in-memory state OR serves any queries -- both of those are now the auto plugin's job, reading the same zone files. The plugin's sole responsibility is now: receive TSIG-authed UPDATE messages, edit the matching zones/<zone>.zone file, bump the SOA serial in CalVer (YYYYMMDDNN) form, and optionally auto-commit to git. What changed: - DELETED: store.go (in-memory recordStore), store_test.go (12 tests), plugin_test.go (10 ServeDNS query tests), old update_test.go. - NEW: zonefile.go -- file-backed authority for one zone. loadRRs via miekg/dns zone parser; mutation helpers (lookupIn/nameExistsIn/ removeRRsetFrom/removeRRFrom/removeNameFrom/addRRTo) on []dns.RR slices; bumpSerial with CalVer semantics + NN exhaustion handling; writeAtomic via temp-file rename; commit shells to `git add && git commit` with configurable author. - NEW: zonefile_test.go -- 17 tests covering load/lookup/mutate/bump/ write paths. - REWRITTEN: plugin.go -- ServeDNS is now thin: UPDATE → TSIG → handler; everything else → Next. No synthetic SOA/NS, no query serving. - REWRITTEN: update.go -- handleUpdate now opens the zoneFile, loads, applies (with prereq checks against the loaded RRs), bumps serial, writes, commits. Detects no-op updates to avoid spurious file writes. - REWRITTEN: setup.go -- new directives: `zones-dir` (required), `auto-commit` (default true), `git-author <name> <email>`. Dropped `nameserver` and `persist`. Validates each declared zone has a file on disk via os.Stat before CoreDNS finishes starting. - REWRITTEN: setup_test.go -- 17 cases for the new grammar. - REWRITTEN: update_test.go -- 11 cases using real temp zone files via t.TempDir(). Total: 30 tests passing, 0 failures. Next: Phase 2c (custom CoreDNS image, deploy, smoke test with nsupdate).
90 lines
3.2 KiB
Go
90 lines
3.2 KiB
Go
// Package rfc2136 is a CoreDNS plugin that accepts dynamic DNS updates
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// per RFC 2136 (UPDATE opcode), authenticated via TSIG, and applies
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// them to on-disk zone files. This is the right shape for stacks where
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// the operator wants to keep zones in flat files (perhaps under git,
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// with HE pulling AXFR), but also wants programmatic updates from
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// clients like Caddy's caddy-dns/rfc2136 module.
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//
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// The plugin does NOT serve any queries — that's the job of the
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// `auto`/`file` plugin running alongside it. This plugin's only
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// responsibility is the UPDATE opcode path: verify TSIG, dissect the
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// UPDATE, write the zone file, bump the SOA serial, optionally
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// auto-commit to git. CoreDNS's auto plugin notices the mtime change
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// and re-serves the zone within its reload interval.
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//
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// See the plan at
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// ~/.claude/plans/dood-does-coredns-offer-enumerated-piglet.md
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// for the architectural rationale.
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package rfc2136
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import (
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"context"
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"github.com/coredns/coredns/plugin"
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"github.com/miekg/dns"
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)
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// DefaultTTL is applied to dynamically-added records whose UPDATE
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// messages carry TTL=0. 60s matches the short-lived nature of ACME
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// challenge records and keeps stale answers from lingering in
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// resolver caches.
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const DefaultTTL uint32 = 60
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// RFC2136 is the plugin handler. One instance per Corefile server block.
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type RFC2136 struct {
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// Next is the downstream plugin in the chain — queries always
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// pass through; only UPDATE opcode is intercepted.
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Next plugin.Handler
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// Zones is the set of canonical (dot-terminated, lowercase) zone
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// names this instance accepts UPDATEs for. UPDATEs for any other
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// zone are rejected with NOTAUTH.
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Zones []string
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// TSIGKeys is keyed by canonical key name (lowercased, trailing
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// dot). Empty means TSIG is disabled — UPDATEs are refused
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// unconditionally as a safety default.
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TSIGKeys map[string]tsigKey
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// TTL is applied to dynamically-injected records that don't carry
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// an explicit TTL in the UPDATE message.
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TTL uint32
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// ZonesDir is the directory where <zone>.zone files live (matching
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// the mount path inside the CoreDNS container). The plugin reads
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// and writes files at <ZonesDir>/<zone>.zone.
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ZonesDir string
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// AutoCommit governs whether the plugin auto-commits zone-file
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// changes to git after every successful UPDATE.
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AutoCommit bool
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// zones holds per-zone file handlers, keyed by canonical zone name.
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// Populated in setup; mutexes live inside each zoneFile.
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zones map[string]*zoneFile
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}
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// Name implements plugin.Handler.
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func (p *RFC2136) Name() string { return "rfc2136" }
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// ServeDNS implements plugin.Handler.
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//
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// Dispatch:
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//
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// UPDATE opcode → verify TSIG, then apply via the UPDATE handler.
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// Anything else → pass through to Next (the auto plugin handles
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// queries against the zone files we maintain).
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func (p *RFC2136) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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if r.Opcode == dns.OpcodeUpdate {
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if err := p.checkTSIG(w, r); err != nil {
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log.Warningf("UPDATE rejected: %v", err)
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resp := new(dns.Msg)
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resp.SetRcode(r, dns.RcodeRefused)
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_ = w.WriteMsg(resp)
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return dns.RcodeRefused, nil
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}
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return p.handleUpdate(w, r)
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}
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return plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r)
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}
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