dns: refactor GetRecords() to allow commands other than sync

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/dns/manager.go

@@ -2,15 +2,16 @@ package dns
 
 import (
 	"context"
-	"errors"
 	"io/fs"
 	"net/netip"
 	"strings"
 
 	"darvaza.org/core"
 	"darvaza.org/slog"
-	"git.jpi.io/amery/jpictl/pkg/cluster"
+	"github.com/libdns/libdns"
 	"golang.org/x/net/publicsuffix"
+
+	"git.jpi.io/amery/jpictl/pkg/cluster"
 )
 
 // Manager is a DNS Manager instance
@@ -71,7 +72,7 @@ func (mgr *Manager) setDefaults() error {
 	}
 
 	if mgr.domain == "" || mgr.suffix == "" {
-		return errors.New("domain not specified")
+		return ErrNoDomain
 	}
 
 	for _, opt := range opts {
@@ -120,6 +121,62 @@ func NewManager(opts ...ManagerOption) (*Manager, error) {
 	return mgr, nil
 }
 
+// GetRecords pulls all the address records on DNS for our domain,
+// optionally only those matching the given names.
+func (mgr *Manager) GetRecords(ctx context.Context, names ...string) ([]libdns.Record, error) {
+	if mgr.p == nil {
+		return nil, ErrNoDNSProvider
+	}
+
+	recs, err := mgr.p.GetRecords(ctx, mgr.domain)
+	switch {
+	case err != nil:
+		// failed
+		return nil, err
+	case len(recs) == 0:
+		// empty
+		return []libdns.Record{}, nil
+	case mgr.suffix == "" && len(names) == 0:
+		// unfiltered
+		return recs, nil
+	default:
+		// filtered
+		recs = mgr.filterRecords(recs, names...)
+		return recs, nil
+	}
+}
+
+func (mgr *Manager) filterRecords(recs []libdns.Record, names ...string) []libdns.Record {
+	out := make([]libdns.Record, 0, len(recs))
+	for _, rr := range recs {
+		name, ok := mgr.matchSuffix(rr)
+		switch {
+		case !ok:
+			// skip, wrong subdomain
+			continue
+		case len(names) == 0:
+			// unfiltered, take it
+		case !core.SliceContains(names, name):
+			// skip, not one of the requested names
+			continue
+		}
+
+		out = append(out, rr)
+	}
+
+	return out
+}
+
+func (mgr *Manager) matchSuffix(rr libdns.Record) (string, bool) {
+	if mgr.suffix == "" {
+		// no suffix
+		return rr.Name, true
+	}
+
+	// remove suffix
+	return strings.CutSuffix(rr.Name, mgr.suffix)
+}
+
 // AddHost registers a host
 func (mgr *Manager) AddHost(_ context.Context, zone string, id int,
 	active bool, addrs ...netip.Addr) error {