Give every view a TSIG key that selects it

Each view's match-clients starts with "key jarl-view-NAME" (after
"!key" for the views listed after it), so a query signed with a view's
key lands in that view from any address. The secrets are derived from a
random seed in Jarl's database. The delegation check signs its queries
to this server's own addresses with the key of the zone's view: before,
they got whichever view matched the server's address, usually internal.
jarl view key / GET /views/{id}/key show a key for dig -k (tsig:write,
audited). jarl-view- key names are reserved; the importer drops view
keys from a configuration Jarl wrote.

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

CHANGELOG.md

@@ -8,6 +8,14 @@ All notable changes to Jarl are documented here. The format follows
 
 ### Added
 
+- View keys: every view gets a TSIG key, `jarl-view-NAME`, at the front of
+  its match-clients, so a query signed with it lands in that view from any
+  address. Jarl signs its delegation check's queries to this server's own
+  addresses with the key of the zone's view: before, they got whichever
+  view matched the server's own address (usually internal), so the check
+  could report the wrong serial for the external view. `jarl view key
+  VIEW` shows a key, for `dig -k` (docs/views.md). The first apply after
+  upgrading adds the keys to named.conf and keys.conf.
 - Server statistics: named's memory (resident, and its own count) and
   CPU use, its cache size, sockets, and recursive and TCP clients against
   their limits; the host's memory and load; free space where zone files,

cmd/jarl/config_cmds.go

@@ -201,7 +201,45 @@ func viewCmd() *cobra.Command {
 			return nil
 		},
 	}
-	cmd.AddCommand(list, create, update, del, order, color)
+	var keyNamed bool
+	key := &cobra.Command{
+		Use:   "key VIEW",
+		Short: "Show the TSIG key that selects a view, to query it from anywhere",
+		Long: `Every view has a TSIG key (jarl-view-NAME) at the front of its
+match-clients: a query signed with it lands in that view, whatever address
+it comes from. Jarl signs its own checks of this server with it; use it to
+see what a view answers:
+
+  jarl view key external                       # shows a ready dig -y command
+  jarl view key external --named-conf > external.key
+  dig -k external.key @SERVER adbraun.lol SOA
+
+Showing it needs tsig:write and is recorded in the audit log.`,
+		Args: cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c, err := newClient()
+			if err != nil {
+				return err
+			}
+			var k struct {
+				Name      string `json:"name"`
+				Algorithm string `json:"algorithm"`
+				Secret    string `json:"secret"`
+			}
+			if err := c.Get(ctx(), "/views/"+url.PathEscape(args[0])+"/key", nil, &k); err != nil {
+				return err
+			}
+			if keyNamed {
+				fmt.Printf("key %q {\n\talgorithm %s;\n\tsecret %q;\n};\n", k.Name, k.Algorithm, k.Secret)
+				return nil
+			}
+			return output(k, func(w io.Writer) {
+				fmt.Fprintf(w, "Key:\t%s\nAlgorithm:\t%s\nSecret:\t%s\ndig:\tdig -y %s:%s:%s @SERVER NAME\n", k.Name, k.Algorithm, k.Secret, k.Algorithm, k.Name, k.Secret)
+			})
+		},
+	}
+	key.Flags().BoolVar(&keyNamed, "named-conf", false, "print a key statement (for dig -k FILE)")
+	cmd.AddCommand(list, create, update, del, order, color, key)
 	return cmd
 }
 

cmd/jarld/admin.go

@@ -302,7 +302,11 @@ func renderCmd() *cobra.Command {
 				return err
 			}
 			paths := render.Paths{ConfigDir: filepath.Join(out, "config"), ZoneDir: filepath.Join(out, "zones"), CacheDir: filepath.Join(out, "cache")}
-			o := render.Render(st, paths, renderExtras(a.cfg))
+			x := renderExtras(a.cfg)
+			if x.ViewKeySeed, err = engine.ViewKeySeed(context.Background(), a.store); err != nil {
+				return err
+			}
+			o := render.Render(st, paths, x)
 			for _, f := range o.Files {
 				if err := os.MkdirAll(filepath.Dir(f.Path), 0o750); err != nil {
 					return err

docs/api.md

@@ -386,6 +386,7 @@ Disabling a record that is already disabled is a 409; with `missing_ok=1`
 | GET / PATCH / DELETE | `/views/{id}` | DELETE `?cascade=1` also deletes the view's zones |
 | POST | `/views/order` | `{"ids": [3, 1, 2]}` |
 | PUT | `/views/{id}/color` | `{"color": "green"}`; `""` for the default |
+| GET | `/views/{id}/key` | `{name, algorithm, secret}`: the TSIG key that selects the view (docs/views.md); needs `tsig:write`, audited |
 
 `adopt_zones` moves zones that are not in a view into the new view. named
 requires every zone to be in a view as soon as one view exists.

docs/cli.md

@@ -368,6 +368,7 @@ jarl view order internal external
 jarl view update external --match-clients "!homelab,any"
 jarl view delete old [--cascade]
 jarl view color internal green                # web UI colour; "default" resets it
+jarl view key external [--named-conf]         # the key that selects the view (dig -k), docs/views.md
 
 jarl acl create homelab 192.168.1.0/24 10.10.0.0/16 localhost
 jarl acl update homelab --add 10.20.0.0/16 --remove 10.10.0.0/16

docs/validation.md

@@ -71,7 +71,7 @@ showing them.
 | `acl_ref_missing`, `key_ref_missing` | error | Every ACL or TSIG key that is referenced must exist |
 | `acl_cycle` | error | ACLs that include each other |
 | `acl_duplicate`, `acl_name_invalid`, `acl_empty`, `acl_shadowed` | error / warning | Unique names, built-in names reserved, elements that can never match |
-| `key_*` | error / warning | Valid key names, a supported algorithm, a base64 secret of a sensible length. hmac-md5/sha1 are flagged as weak |
+| `key_*` | error / warning | Valid key names, a supported algorithm, a base64 secret of a sensible length. hmac-md5/sha1 are flagged as weak. Names starting with `jarl-view-` are reserved for the view keys (`key_name_reserved`) |
 | `view_duplicate`, `view_name_invalid`, `view_acl_invalid` | error | Valid, unique views and match lists |
 | `view_unreachable` | warning | A view that comes after one matching every client is never used |
 | `option_unknown`, `option_scope_invalid` | error | The option must exist in BIND 9.20 and be allowed where it is set (server, view, zone of this type, top level) |

docs/views.md

@@ -116,7 +116,44 @@ dig @<public-ip> example.com                            # from outside: status R
 jarl check
 ```
 
-On the server, `dig -b <source address>` picks which view you test.
+On the server, `dig -b <source address>` picks which view you test, or,
+from anywhere, sign the query with the view's key (below):
+
+```sh
+jarl view key external --named-conf > external.key
+dig -k external.key @ns1.adbraun.lol nas.adbraun.lol +short   # 203.0.113.20, even from the LAN
+```
+
+## View keys
+
+named picks a view by where a query comes from, so a query this server
+sends to its own public address usually lands in the internal view: its
+source is one of your own networks. That makes checks of the external view
+from the server itself (such as Jarl's delegation check) see the wrong
+view.
+
+So Jarl gives every view a TSIG key, `jarl-view-NAME`, and puts it at the
+front of the view's `match-clients`:
+
+```
+view "internal" {
+	match-clients { !key jarl-view-external; key jarl-view-internal; homelab; };
+	...
+view "external" {
+	match-clients { key jarl-view-external; any; };
+```
+
+A query signed with a view's key lands in that view, whatever its source;
+the `!key` stops an earlier view from taking a later view's queries.
+Clients don't send these keys, so for them nothing changes. Jarl signs its
+own queries to this server's addresses with the key of the zone's view.
+The keys live in `keys.conf` with your other keys, never in diffs or in
+`jarl tsig list`; their secrets are derived from a random value in Jarl's
+database (and in its backups), so they stay the same from one apply to
+the next. `jarl view key VIEW`
+shows one (it needs `tsig:write` and is audited). Key names starting with
+`jarl-view-` are reserved, and the view keys can be used in your own
+options (`allow-transfer { key jarl-view-external; }`).
 
 ## Living with views
 
@@ -130,7 +167,9 @@ On the server, `dig -b <source address>` picks which view you test.
   `jarl view list` shows it.
 * Deleting a view is refused while it still has zones, unless you pass
   `--cascade`.
-* Give each view a colour (Views → Edit → Colour, or
+* Each view has its own page (Views → the view's name): its settings,
+  options and zones.
+* Give each view a colour (the view's page → Settings → Colour, or
   `jarl view color internal green`) to tell the zones of each view apart
   in the zone list. The colour only affects the web UI, so it applies at
   once, with no changeset or deploy. `jarl view color internal default`

internal/engine/blocklists.go

@@ -78,7 +78,7 @@ func (e *Engine) RefreshDue(ctx context.Context) {
 		e.log.Warn("blocklists: loading their status failed", "err", err)
 		return
 	}
-	out := render.Render(st, e.cfg.Paths, e.cfg.Extras)
+	out := render.Render(st, e.cfg.Paths, e.extras(ctx))
 	if err := e.ensureBlocklistFiles(out.Blocklists); err != nil {
 		e.log.Warn("blocklists: creating empty zone files failed", "err", err)
 	}

internal/engine/engine.go

@@ -75,6 +75,9 @@ type Engine struct {
 	Limits BlocklistLimits
 
 	namedCheck namedCheck // named-checkconf on the running configuration (namedwarn.go)
+
+	seedMu sync.Mutex
+	seed   []byte // the view keys' seed (viewkeys.go)
 }
 
 // New creates an engine.
@@ -437,7 +440,7 @@ func (e *Engine) makePlan(ctx context.Context, base, work *model.State, user str
 		pl.introduced = append(pl.introduced, problems...)
 		return pl, nil
 	}
-	pl.out = render.Render(work, e.cfg.Paths, e.cfg.Extras)
+	pl.out = render.Render(work, e.cfg.Paths, e.extras(ctx))
 	deployed, err := e.store.DeployedFiles(ctx)
 	if err != nil {
 		return nil, err
@@ -473,7 +476,7 @@ func (e *Engine) makePlan(ctx context.Context, base, work *model.State, user str
 	pl.diff = diff.String()
 
 	// Which zones named must reload, and which serials to verify.
-	baseOut := render.Render(base, e.cfg.Paths, e.cfg.Extras)
+	baseOut := render.Render(base, e.cfg.Paths, e.extras(ctx))
 	changedPaths := map[string]bool{}
 	for _, f := range pl.changed {
 		changedPaths[f.Path] = true
@@ -529,7 +532,7 @@ func (e *Engine) stagingCheck(ctx context.Context, pl *plan) error {
 	}
 	defer os.RemoveAll(dir)
 	sp := render.Paths{ConfigDir: filepath.Join(dir, "config"), ZoneDir: filepath.Join(dir, "zones"), CacheDir: filepath.Join(dir, "cache")}
-	sout := render.Render(pl.work, sp, e.cfg.Extras)
+	sout := render.Render(pl.work, sp, e.extras(ctx))
 	for _, d := range sout.Dirs {
 		if err := os.MkdirAll(d, 0o750); err != nil {
 			return err

internal/engine/namedwarn.go

@@ -54,7 +54,7 @@ func (e *Engine) namedProblems(ctx context.Context, st *model.State, deployed ma
 	if err != nil {
 		return nil // named-checkconf couldn't run; an apply reports that
 	}
-	out := render.Render(st, e.cfg.Paths, e.cfg.Extras)
+	out := render.Render(st, e.cfg.Paths, e.extras(ctx))
 	var ps []validate.Problem
 	for _, m := range res.Messages {
 		p := validate.Problem{Severity: validate.Warning, Code: "named_warning", View: m.View, Zone: m.Zone}

internal/engine/viewkeys.go

@@ -0,0 +1,68 @@
+package engine
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+
+	"jarl/internal/model"
+	"jarl/internal/nscheck"
+	"jarl/internal/render"
+	"jarl/internal/store"
+)
+
+// viewKeySeedMeta is where the seed of the view keys is kept.
+const viewKeySeedMeta = "view_key_seed"
+
+// ViewKeySeed returns the seed the view keys' secrets are derived from
+// (render/viewkeys.go), creating it the first time.
+func ViewKeySeed(ctx context.Context, st *store.Store) ([]byte, error) {
+	v, err := st.GetMeta(ctx, viewKeySeedMeta)
+	if err == nil {
+		return base64.StdEncoding.DecodeString(v)
+	}
+	if !errors.Is(err, store.ErrNotFound) {
+		return nil, err
+	}
+	seed := make([]byte, 32)
+	if _, err := rand.Read(seed); err != nil {
+		return nil, err
+	}
+	if err := st.SetMeta(ctx, viewKeySeedMeta, base64.StdEncoding.EncodeToString(seed)); err != nil {
+		return nil, err
+	}
+	return seed, nil
+}
+
+// extras returns what jarld's configuration adds to the rendered
+// configuration, with the view keys' seed.
+func (e *Engine) extras(ctx context.Context) render.Extras {
+	x := e.cfg.Extras
+	e.seedMu.Lock()
+	defer e.seedMu.Unlock()
+	if e.seed == nil {
+		seed, err := ViewKeySeed(ctx, e.store)
+		if err != nil {
+			e.log.Warn("view keys: reading their seed failed", "err", err)
+			return x
+		}
+		e.seed = seed
+	}
+	x.ViewKeySeed = e.seed
+	return x
+}
+
+// ViewKey returns the TSIG key that selects a zone's view on this server
+// (nil without views).
+func (e *Engine) ViewKey(ctx context.Context, st *model.State, z *model.Zone) *nscheck.Key {
+	v := st.Views[z.ViewID]
+	if v == nil {
+		return nil
+	}
+	x := e.extras(ctx)
+	if len(x.ViewKeySeed) == 0 {
+		return nil
+	}
+	return &nscheck.Key{Name: render.ViewKeyName(v.Name), Algorithm: render.ViewKeyAlgorithm, Secret: render.ViewKeySecret(x.ViewKeySeed, v.ID)}
+}

internal/importer/importer.go

@@ -393,6 +393,10 @@ func (im *importer) key(s *namedconf.Stmt) error {
 		return fmt.Errorf("%s: key without a block", s.Pos)
 	}
 	name := model.NormalizeKeyName(s.Arg(0))
+	if strings.HasPrefix(name, model.ViewKeyPrefix) {
+		// A view key from a configuration Jarl wrote: Jarl makes its own.
+		return nil
+	}
 	alg, secret := "", ""
 	if a := namedconf.FindOne(b.Stmts, "algorithm"); a != nil {
 		alg = strings.ToLower(a.Arg(0))
@@ -433,7 +437,7 @@ func (im *importer) view(s *namedconf.Stmt) error {
 		switch kw := st.Keyword(); kw {
 		case "match-clients":
 			if mb := st.FirstBlock(); mb != nil {
-				v.MatchClients = nonNil(elementStrings(mb))
+				v.MatchClients = withoutViewKeys(nonNil(elementStrings(mb)))
 			}
 		case "match-destinations":
 			if mb := st.FirstBlock(); mb != nil {
@@ -807,3 +811,23 @@ func allowsNone(o *namedconf.Stmt) bool {
 	}
 	return true
 }
+
+// withoutViewKeys drops the view keys Jarl puts in front of match-clients
+// (render/viewkeys.go) from a list read from a configuration Jarl wrote,
+// and the "any" it adds after them to a view that had no list.
+func withoutViewKeys(elems []string) []string {
+	out := []string{}
+	dropped := false
+	for _, e := range elems {
+		f := strings.Fields(strings.TrimPrefix(strings.TrimSpace(e), "!"))
+		if len(f) == 2 && f[0] == "key" && strings.HasPrefix(strings.Trim(f[1], `"`), model.ViewKeyPrefix) {
+			dropped = true
+			continue
+		}
+		out = append(out, e)
+	}
+	if dropped && len(out) == 1 && out[0] == "any" {
+		return []string{}
+	}
+	return out
+}

internal/importer/importer_test.go

@@ -205,3 +205,15 @@ view "internal" {
 		t.Errorf("imported state has errors: %v", ps)
 	}
 }
+
+func TestWithoutViewKeys(t *testing.T) {
+	for _, tc := range []struct{ in, want []string }{
+		{[]string{"!key jarl-view-external", `key "jarl-view-internal"`, "homelab"}, []string{"homelab"}},
+		{[]string{"key jarl-view-external", "any"}, []string{}},
+		{[]string{"key xfer", "any"}, []string{"key xfer", "any"}},
+	} {
+		if got := withoutViewKeys(tc.in); strings.Join(got, ";") != strings.Join(tc.want, ";") || got == nil {
+			t.Errorf("%v: %v, want %v", tc.in, got, tc.want)
+		}
+	}
+}

internal/model/model.go

@@ -384,6 +384,13 @@ func (s *State) KeyByName(name string) *TSIGKey {
 	return nil
 }
 
+// ViewKeyPrefix starts the names of the TSIG keys Jarl gives views
+// (render/viewkeys.go); other keys can't use it.
+const ViewKeyPrefix = "jarl-view-"
+
+// ViewKeyName returns the name of a view's key.
+func ViewKeyName(view string) string { return ViewKeyPrefix + view }
+
 // NormalizeKeyName returns the canonical form of a key name: lowercase,
 // without a trailing dot.
 func NormalizeKeyName(name string) string {

internal/nscheck/localkey_test.go

@@ -0,0 +1,52 @@
+package nscheck
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+// A query to this host's own address is signed with LocalKey, so a server
+// with views answers from the view that key selects.
+func TestLocalKey(t *testing.T) {
+	zone := "example.com."
+	key := &Key{Name: "jarl-view-external.", Algorithm: "hmac-sha256", Secret: "c2VjcmV0LXNlY3JldC1zZWNyZXQtc2VjcmV0LXNlY3I="}
+	pc, err := net.ListenPacket("udp", "127.0.0.1:0")
+	if err != nil {
+		t.Skip(err)
+	}
+	_, port, _ := net.SplitHostPort(pc.LocalAddr().String())
+	srv := &dns.Server{PacketConn: pc, TsigSecret: map[string]string{key.Name: key.Secret},
+		Handler: dns.HandlerFunc(func(w dns.ResponseWriter, req *dns.Msg) {
+			// Signed with the view key: the "external" view's serial.
+			serial := "1"
+			signed := req.IsTsig() != nil && w.TsigStatus() == nil
+			if signed {
+				serial = "2"
+			}
+			m := new(dns.Msg)
+			m.SetReply(req)
+			m.Authoritative = true
+			m.Answer = []dns.RR{rr(zone + " 3600 IN SOA ns1." + zone + " admin." + zone + " " + serial + " 3600 900 1209600 300")}
+			if signed {
+				m.SetTsig(key.Name, dns.HmacSHA256, 300, time.Now().Unix())
+			}
+			w.WriteMsg(m)
+		})}
+	go srv.ActivateAndServe()
+	t.Cleanup(func() { srv.Shutdown() })
+
+	ref := uint32(2)
+	c := &Checker{Timeout: time.Second, Port: port, IsLocal: func(netip.Addr) bool { return false }}
+	if res := c.Serials(context.Background(), zone, &ref, []Target{{Addresses: []string{"127.0.0.1"}}}); res[0].Status != "behind" {
+		t.Errorf("unsigned: %+v (want the other view's serial)", res[0])
+	}
+	c.LocalKey = key
+	if res := c.Serials(context.Background(), zone, &ref, []Target{{Addresses: []string{"127.0.0.1"}}}); res[0].Status != "in_sync" {
+		t.Errorf("signed with the view key: %+v", res[0])
+	}
+}

internal/nscheck/nscheck.go

@@ -95,6 +95,11 @@ type Checker struct {
 	// IsLocal reports whether an address belongs to this host (default:
 	// its interface addresses and loopback).
 	IsLocal func(netip.Addr) bool
+	// LocalKey, when set, signs the queries sent to this host's own
+	// addresses (when they are asked): with views, the key that selects
+	// the zone's view, so the answer comes from that view and not from
+	// whichever view matches this host's address.
+	LocalKey *Key
 	// Watch, if set, is told about each DNS query the checks send and
 	// its outcome as it happens (the web UI shows them while it waits).
 	// It is called from several goroutines at once.
@@ -465,13 +470,17 @@ func (c *Checker) Serials(ctx context.Context, zone string, ref *uint32, targets
 			}
 			// Reported here rather than by exchange: the end carries the
 			// server's status.
-			id := c.startEvent(digLine(r.Address, port, zone, "SOA", true, t.Key))
+			key := t.Key
+			if key == nil && c.LocalKey != nil && IsLocalAddr(ip) {
+				key = c.LocalKey
+			}
+			id := c.startEvent(digLine(r.Address, port, zone, "SOA", true, key))
 			go func(r Result, key *Key) {
 				defer wg.Done()
 				c.soa(ctx, zone, key, ref, &r)
 				c.endEvent(Event{ID: id, Result: &r, RTTMs: r.RTTMs})
 				add(r)
-			}(r, t.Key)
+			}(r, key)
 		}
 	}
 	wg.Wait()

internal/render/render.go

@@ -149,7 +149,7 @@ const headerText = "Generated by Jarl. DO NOT EDIT: changes made here are overwr
 // from jarld's configuration (e.g. for query statistics).
 func Render(s *model.State, p Paths, x Extras) *Output {
 	out := &Output{Spans: map[string][]Span{}, ZoneFiles: map[int64]string{}}
-	keys := renderKeys(s)
+	keys := renderKeys(s) + renderViewKeys(s, x)
 	out.Files = append(out.Files, &File{Path: p.KeysConfig(), Content: []byte(keys), Mode: 0o640, Kind: KindKeys, Secret: true})
 	conf, spans := renderConfig(s, p, x, out)
 	out.Files = append(out.Files, &File{Path: p.MainConfig(), Content: []byte(conf), Mode: 0o640, Kind: KindConfig})
@@ -350,8 +350,8 @@ func renderConfig(s *model.State, p Paths, x Extras, out *Output) (string, []Spa
 			w.write(commentBlock("//", v.Comment))
 		}
 		w.write(fmt.Sprintf("view %s {\n", namedconf.QuoteString(v.Name)))
-		if len(v.MatchClients) > 0 {
+		if mc := viewMatchClients(s, x, v); len(mc) > 0 {
-			writeAML(w, "match-clients", v.MatchClients)
+			writeAML(w, "match-clients", mc)
 		}
 		if len(v.MatchDestinations) > 0 {
 			writeAML(w, "match-destinations", v.MatchDestinations)

internal/render/stats.go

@@ -15,6 +15,9 @@ type Extras struct {
 	// Stats, when set, makes named publish what Jarl's statistics
 	// collector reads.
 	Stats *StatsHooks
+	// ViewKeySeed, when set, gives every view a TSIG key that selects it
+	// (viewkeys.go).
+	ViewKeySeed []byte
 }
 
 // StatsHooks describe the statistics channel and response log Jarl needs.

internal/render/viewkeys.go

@@ -0,0 +1,84 @@
+package render
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"strconv"
+	"strings"
+
+	"jarl/internal/model"
+	"jarl/internal/namedconf"
+)
+
+// View keys let Jarl choose a view regardless of where a query comes from:
+// each view gets a TSIG key, and its match-clients starts with that key
+// (after excluding the keys of the views listed after it, so no earlier
+// view takes their queries). Queries signed with a view's key always land
+// in that view. Jarl signs its own checks of this server's addresses with
+// them (a query from this host would otherwise land in whichever view
+// matches this host's address), and you can too: dig -k.
+//
+// The secrets are derived from a random seed kept in Jarl's database
+// (Extras.ViewKeySeed), so they stay the same from one apply to the next
+// and need no storage of their own. They are in keys.conf with the other
+// keys.
+
+// ViewKeyAlgorithm is the view keys' algorithm.
+const ViewKeyAlgorithm = "hmac-sha256"
+
+// ViewKeyName returns the name of a view's key.
+func ViewKeyName(view string) string { return model.ViewKeyName(view) }
+
+// IsViewKey reports whether a key name is a view key's.
+func IsViewKey(name string) bool {
+	return strings.HasPrefix(strings.ToLower(strings.TrimSuffix(name, ".")), model.ViewKeyPrefix)
+}
+
+// ViewKeySecret returns the secret of the key of the view with this ID.
+func ViewKeySecret(seed []byte, viewID int64) string {
+	m := hmac.New(sha256.New, seed)
+	m.Write([]byte("jarl view key " + strconv.FormatInt(viewID, 10)))
+	return base64.StdEncoding.EncodeToString(m.Sum(nil))
+}
+
+// viewKeysOn reports whether view keys are rendered.
+func viewKeysOn(s *model.State, x Extras) bool { return len(x.ViewKeySeed) > 0 && len(s.Views) > 0 }
+
+// renderViewKeys returns the key statements of the views' keys.
+func renderViewKeys(s *model.State, x Extras) string {
+	if !viewKeysOn(s, x) {
+		return ""
+	}
+	var sb strings.Builder
+	sb.WriteString("\n" + commentBlock("//", "View keys: a query signed with one of these always lands in its view.\nJarl signs its own checks of this server with them; dig -k works too."))
+	for _, v := range s.OrderedViews() {
+		sb.WriteString("key " + namedconf.QuoteString(ViewKeyName(v.Name)) + " {\n\talgorithm " + ViewKeyAlgorithm + ";\n\tsecret " + namedconf.QuoteString(ViewKeySecret(x.ViewKeySeed, v.ID)) + ";\n};\n")
+	}
+	return sb.String()
+}
+
+// viewMatchClients returns a view's match-clients with the view keys in
+// front: "!key" for the keys of the views after it, then its own key, then
+// the view's own list ("any" when it has none, which is what an absent
+// match-clients means).
+func viewMatchClients(s *model.State, x Extras, v *model.View) []string {
+	if !viewKeysOn(s, x) {
+		return v.MatchClients
+	}
+	var out []string
+	after := false
+	for _, o := range s.OrderedViews() {
+		if after {
+			out = append(out, "!key "+namedconf.QuoteString(ViewKeyName(o.Name)))
+		}
+		if o.ID == v.ID {
+			after = true
+		}
+	}
+	out = append(out, "key "+namedconf.QuoteString(ViewKeyName(v.Name)))
+	if len(v.MatchClients) == 0 {
+		return append(out, "any")
+	}
+	return append(out, v.MatchClients...)
+}

internal/render/viewkeys_test.go

@@ -0,0 +1,51 @@
+package render
+
+import (
+	"strings"
+	"testing"
+
+	"jarl/internal/model"
+)
+
+func TestViewKeys(t *testing.T) {
+	s := model.NewState()
+	s.Views[1] = &model.View{ID: 1, Name: "internal", Position: 0, MatchClients: []string{"homelab", "localhost"}}
+	s.Views[2] = &model.View{ID: 2, Name: "external", Position: 1}
+	p := Paths{ConfigDir: "/etc/bind/jarl", ZoneDir: "/var/lib/bind/jarl", CacheDir: "/var/cache/bind/jarl"}
+	seed := []byte("0123456789abcdef0123456789abcdef")
+	files := func(x Extras) (conf, keys string) {
+		for _, f := range Render(s, p, x).Files {
+			switch f.Kind {
+			case KindConfig:
+				conf = string(f.Content)
+			case KindKeys:
+				keys = string(f.Content)
+			}
+		}
+		return
+	}
+	conf, keys := files(Extras{ViewKeySeed: seed})
+	for _, want := range []string{
+		// An earlier view mustn't take a later view's key.
+		"match-clients {\n\t\t!key jarl-view-external;\n\t\tkey jarl-view-internal;\n\t\thomelab;\n\t\tlocalhost;\n\t};",
+		// A view without a list matched everyone: it still does.
+		"match-clients { key jarl-view-external; any; };",
+	} {
+		if !strings.Contains(conf, want) {
+			t.Errorf("named.conf lacks\n%s\n---\n%s", want, conf)
+		}
+	}
+	sec := ViewKeySecret(seed, 2)
+	if !strings.Contains(keys, "key \"jarl-view-external\" {\n\talgorithm hmac-sha256;\n\tsecret \""+sec+"\";\n};") || !strings.Contains(keys, "jarl-view-internal") {
+		t.Errorf("keys.conf:\n%s", keys)
+	}
+	// The same seed gives the same secret; another seed doesn't.
+	if ViewKeySecret(seed, 2) != sec || ViewKeySecret([]byte("other"), 2) == sec || ViewKeySecret(seed, 1) == sec {
+		t.Error("secrets aren't derived from the seed and the view")
+	}
+	// Without a seed (or without views), nothing changes.
+	conf, keys = files(Extras{})
+	if strings.Contains(conf, "jarl-view-") || strings.Contains(keys, "jarl-view-") {
+		t.Errorf("view keys without a seed:\n%s", conf)
+	}
+}

internal/server/h_config.go

@@ -14,6 +14,7 @@ import (
 	"jarl/internal/dnsname"
 	"jarl/internal/engine"
 	"jarl/internal/model"
+	"jarl/internal/render"
 	"jarl/internal/rr"
 )
 
@@ -92,6 +93,31 @@ func (s *Server) getView(w http.ResponseWriter, r *http.Request, p *auth.Princip
 	return nil
 }
 
+// viewKey: GET /views/{id}/key is the TSIG key that selects the view
+// (render/viewkeys.go), with its secret: like revealing a TSIG key's, it
+// needs tsig:write and is audited.
+func (s *Server) viewKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
+	st, err := s.state(r)
+	if err != nil {
+		return err
+	}
+	v, err := s.viewByPath(r, st, p)
+	if err != nil {
+		return err
+	}
+	if err := require(p, auth.Action{Resource: auth.ResTSIG, Write: true}); err != nil {
+		return forbidden("showing a view's key needs tsig:write")
+	}
+	seed, err := engine.ViewKeySeed(r.Context(), s.store)
+	if err != nil {
+		return err
+	}
+	name := render.ViewKeyName(v.Name)
+	s.eng.Audit(r.Context(), p, "tsig.reveal", "view", v.ID, v.Name, "success", "view key "+name+" shown")
+	writeJSON(w, http.StatusOK, map[string]string{"name": name, "algorithm": render.ViewKeyAlgorithm, "secret": render.ViewKeySecret(seed, v.ID)})
+	return nil
+}
+
 func (s *Server) viewObject(r *http.Request) func(st *model.State, id int64) any {
 	return func(st *model.State, id int64) any {
 		if v := st.Views[id]; v != nil {

internal/server/h_nscheck.go

@@ -160,6 +160,9 @@ func (s *Server) zoneDelegation(w http.ResponseWriter, r *http.Request, p *auth.
 		return badRequest("the delegation check compares the parent's delegation with the zone's NS records, so it needs a primary zone (this is a %s zone; check it where its primary is)", z.Type)
 	}
 	c := s.checker()
+	// This server's own addresses are asked too: sign those queries with
+	// the key of the zone's view, so they get that view's answer.
+	c.LocalKey = s.eng.ViewKey(r.Context(), st, z)
 	if v := r.URL.Query().Get("resolver"); v != "" {
 		// An address only, always port 53: this is a DNS resolver.
 		a, err := netip.ParseAddr(v)

internal/server/routes.go

@@ -52,6 +52,7 @@ func (s *Server) routes() {
 	m.HandleFunc("POST "+p+"/views", s.authed(s.createView))
 	m.HandleFunc("POST "+p+"/views/order", s.authed(s.reorderViews))
 	m.HandleFunc("GET "+p+"/views/{id}", s.authed(s.getView))
+	m.HandleFunc("GET "+p+"/views/{id}/key", s.authed(s.viewKey))
 	m.HandleFunc("PATCH "+p+"/views/{id}", s.authed(s.updateView))
 	m.HandleFunc("DELETE "+p+"/views/{id}", s.authed(s.deleteView))
 	m.HandleFunc("PUT "+p+"/views/{id}/color", s.authed(s.setViewColor))

internal/validate/config.go

@@ -57,6 +57,8 @@ func (c *checker) checkKeys() {
 			c.errf("key_name_invalid", "key", k.ID, "TSIG key has no name")
 		} else if err := dnsname.CheckZoneName(dnsname.Fqdn(k.Name)); err != nil {
 			c.errf("key_name_invalid", "key", k.ID, "%s: invalid name: %v", label, err)
+		} else if strings.HasPrefix(strings.ToLower(k.Name), model.ViewKeyPrefix) {
+			c.errf("key_name_reserved", "key", k.ID, "%s: names starting with %s are kept for the keys Jarl gives views", label, model.ViewKeyPrefix)
 		}
 		minLen, ok := TSIGAlgorithms[k.Algorithm]
 		if !ok {

internal/validate/validate.go

@@ -126,6 +126,10 @@ func State(s *model.State, opts Options) []Problem {
 	for _, k := range s.Keys {
 		c.keyNames[k.Name] = true
 	}
+	// The views' own keys (render/viewkeys.go) may be referred to too.
+	for _, v := range s.Views {
+		c.keyNames[model.NormalizeKeyName(model.ViewKeyName(v.Name))] = true
+	}
 	for _, k := range opts.ExternalKeys {
 		c.keyNames[model.NormalizeKeyName(k)] = true
 	}

scripts/e2e.sh

@@ -297,6 +297,13 @@ contains "token.revoke"
 run "view create (adopts zones)" 0 $J view create internal --match-clients homelab --adopt-zones
 run "view create external" 0 $J view create external --match-clients any
 run "zone create in external" 0 $J zone create adbraun.test --view external --ns ns1.adbraun.test. --record "ns1 A 203.0.113.1"
+# View keys: a query signed with a view's key lands in that view, from
+# any address (this host is in homelab, so unsigned it gets internal).
+run "view key" 0 sh -c "$J view key external --named-conf > $E/external.key"
+expect_dig "unsigned from here: the internal view" "127.0.0.1" ns1.adbraun.test A
+expect_dig "signed with the external view's key" "203.0.113.1" -k $E/external.key ns1.adbraun.test A
+run "view key shows a dig command" 0 $J view key external
+contains "dig -y hmac-sha256:jarl-view-external:"
 # named-checkconf's own warnings stay on the dashboard after the apply.
 run "option set recursion no (external)" 0 $J option set recursion no --view external
 run "allow-recursion without its braces" 0 $J option set allow-recursion 192.0.2.1 --view external