Add DNSSEC signing, key backups and Porkbun support

Zones get a DNSSEC setting: named signs them with BIND's default (or a
custom) dnssec-policy and inline signing, with keys in a per-view key
directory. Jarl shows the keys, the DS record and when it is safe to
publish it, checks the parent's DS records (check-ds, which also tells
named), and refuses steps that would break a signed domain: switching
straight to unsigned, finishing a turn-off too early, deleting or moving
a signed zone, TTLs above max-zone-ttl. Turning off goes through the
insecure policy; wipe starts over once the parent has no DS.

Backups store the DNSSEC keys and restore puts them back for named; the
backup unit gets CAP_DAC_READ_SEARCH to read them. Jarl raises a zone's
serial above named's whenever it writes an older one (after a restore).
The serials check compares the signed serial.

With a Porkbun API key in jarl.yaml, the registrar's name servers, glue
records and DS records can be shown and changed, each change checked
first (dry run, force to override).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/h_nscheck.go

@@ -17,6 +17,7 @@ import (
 	"jarl/internal/api"
 	"jarl/internal/auth"
 	"jarl/internal/dnsname"
+	"jarl/internal/dnssec"
 	"jarl/internal/model"
 	"jarl/internal/namedconf"
 	"jarl/internal/nscheck"
@@ -61,6 +62,11 @@ func (s *Server) zoneSerials(w http.ResponseWriter, r *http.Request, p *auth.Pri
 	if err != nil {
 		resp.Notes = append(resp.Notes, "named on this server didn't report the zone's serial: "+err.Error())
 	}
+	if z.Signed() && resp.SerialSource == "jarl" {
+		// named gives the signed zone its own serial, ahead of Jarl's.
+		resp.Notes = append(resp.Notes, "The zone is signed and named wasn't asked: other servers serve the signed zone's serial, which named sets and which is usually ahead of Jarl's.")
+		resp.Serial = nil
+	}
 	if len(targets) == 0 {
 		if z.Type == model.ZonePrimary {
 			resp.Notes = append(resp.Notes, "The zone has no NS records or also-notify targets to check.")
@@ -116,7 +122,7 @@ func (s *Server) zoneDelegation(w http.ResponseWriter, r *http.Request, p *auth.
 	ctx, cancel := context.WithTimeout(r.Context(), 30*time.Second)
 	defer cancel()
 	ref, _, _ := s.localSerial(ctx, st, z)
-	resp := api.DelegationResponse{DelegationReport: c.Delegation(ctx, z.Name, ns, addrs, ref), View: st.ViewName(z), Notes: []string{}, CheckedAt: time.Now()}
+	resp := api.DelegationResponse{DelegationReport: c.Delegation(ctx, z.Name, ns, addrs, ref, s.signing(ctx, st, z)), View: st.ViewName(z), Notes: []string{}, CheckedAt: time.Now()}
 	if resp.View != "" {
 		resp.Notes = append(resp.Notes, fmt.Sprintf("Compared with the zone in view %s. Resolvers on the internet get the view that matches their address; make sure that's this one.", resp.View))
 	}
@@ -124,6 +130,18 @@ func (s *Server) zoneDelegation(w http.ResponseWriter, r *http.Request, p *auth.
 	return nil
 }
 
+// signing describes how Jarl signs z, for comparing with the parent's DS
+// records: the DS of every key-signing key named still publishes.
+func (s *Server) signing(ctx context.Context, st *model.State, z *model.Zone) *nscheck.Signing {
+	sig := &nscheck.Signing{Policy: z.DNSSECPolicy}
+	for _, k := range s.eng.DNSSEC(ctx, st, z).Keys {
+		if k.DS != nil && k.DNSKEYState != dnssec.Hidden {
+			sig.DS = append(sig.DS, *k.DS)
+		}
+	}
+	return sig
+}
+
 // localSerial is the serial this server serves for z: named's, or for a
 // primary zone Jarl's when named isn't asked.
 func (s *Server) localSerial(ctx context.Context, st *model.State, z *model.Zone) (*uint32, string, error) {