Reverse zones: other views' addresses aren't missing PTRs

A reverse zone's missing PTR count covers only its own view's A and
AAAA records. Addresses only other views' records use are counted apart
(ptr_other_views, 'Other views' in zone show, a note on the zone page)
and filled only when asked: fill-ptr --other-views, zone create
--fill --other-views, or the New reverse zone dialog's checkbox. This
keeps one view's host names out of another view's reverse zones.

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

internal/engine/reverse.go

@@ -87,11 +87,12 @@ type PTRFill struct {
 // PTRFills returns the PTR records a reverse zone named zoneName in a view
 // lacks for the addresses of the view's A and AAAA records: one per
 // address, naming its mail or name server host when it is one, otherwise
-// a host rather than the domain itself, then the shortest name. An
-// address no record of the view uses is named from another view's
-// records (fillAddresses), marked From. existing are the zone's records
-// (none for a new zone).
-func PTRFills(st *model.State, viewID int64, zoneName string, existing []*model.Record) []PTRFill {
+// a host rather than the domain itself, then the shortest name. With
+// otherViews, an address no record of the view uses is named from another
+// view's records (fillAddresses), marked From; that is only on request,
+// since it publishes one view's host names in another. existing are the
+// zone's records (none for a new zone).
+func PTRFills(st *model.State, viewID int64, zoneName string, existing []*model.Record, otherViews bool) []PTRFill {
 	prefix, ok := dnsname.PrefixFromReverse(zoneName)
 	if !ok {
 		return nil
@@ -105,7 +106,11 @@ func PTRFills(st *model.State, viewID int64, zoneName string, existing []*model.
 	servers := serverNames(st, viewID)
 	byAddr := map[netip.Addr][]addrUse{}
 	var order []netip.Addr
-	for _, u := range fillAddresses(st, viewID) {
+	addrs := forwardAddresses(st, viewID)
+	if otherViews {
+		addrs = fillAddresses(st, viewID)
+	}
+	for _, u := range addrs {
 		if !prefix.Contains(u.addr) {
 			continue
 		}
@@ -195,9 +200,23 @@ func displayAll(names []string) []string {
 	return out
 }
 
+// otherViewsHint says how many addresses only other views' records use in
+// a reverse zone, and how to add them; "" when there are none.
+func otherViewsHint(st *model.State, viewID int64, zoneName string, existing []*model.Record, own int, how string) string {
+	n := len(PTRFills(st, viewID, zoneName, existing, true)) - own
+	if n <= 0 {
+		return ""
+	}
+	what := "addresses"
+	if n == 1 {
+		what = "address"
+	}
+	return fmt.Sprintf("%d %s in %s only other views' records use; %s", n, what, dnsname.Display(zoneName), how)
+}
+
 // zoneFillPTR expands zone.fill_ptr: the PTR records a reverse zone lacks.
 func (x *expander) zoneFillPTR(req Request) ([]model.Op, error) {
-	var in LinkInput
+	var in FillPTRInput
 	if err := decode(req.Data, &in); err != nil {
 		return nil, err
 	}
@@ -215,9 +234,15 @@ func (x *expander) zoneFillPTR(req Request) ([]model.Op, error) {
 	if _, ok := dnsname.PrefixFromReverse(z.Name); !ok {
 		return nil, errf(KindBadRequest, "zone %s isn't a reverse zone of whole octets or nibbles (like 10.0.10.in-addr.arpa)", zoneDesc(x.st, z))
 	}
-	fills := PTRFills(x.st, z.ViewID, z.Name, x.st.ZoneRecords(z.ID))
+	fills := PTRFills(x.st, z.ViewID, z.Name, x.st.ZoneRecords(z.ID), in.OtherViews)
 	if len(fills) == 0 {
-		return nil, errf(KindBadRequest, "nothing to add: every address of %s's A and AAAA records in %s has a PTR record", viewOrServer(x.st, z.ViewID), zoneDesc(x.st, z))
+		msg := fmt.Sprintf("nothing to add: every address of %s's A and AAAA records in %s has a PTR record", viewOrServer(x.st, z.ViewID), zoneDesc(x.st, z))
+		if !in.OtherViews {
+			if h := otherViewsHint(x.st, z.ViewID, z.Name, x.st.ZoneRecords(z.ID), 0, "to name them from there, fill with other views (--other-views)"); h != "" {
+				msg += "; " + h
+			}
+		}
+		return nil, errf(KindBadRequest, "%s", msg)
 	}
 	x.warnings = append(x.warnings, fillWarnings(fills)...)
 	ids, err := x.ids(len(fills))
@@ -415,7 +440,7 @@ func ReverseCandidates(st *model.State, exposures []validate.Exposure, local []n
 				continue
 			}
 			s := ReverseSuggestion{ViewID: sc.id, View: viewName(st, sc.id), Prefix: p.String(), Zone: strings.TrimSuffix(name, "."), Group: group, Hidden: hidden, Why: why, Samples: []string{}}
-			fills := PTRFills(st, sc.id, name, nil)
+			fills := PTRFills(st, sc.id, name, nil, opt.All && opt.View != "")
 			s.Fill = len(fills)
 			for i, f := range fills {
 				if i == 3 {