types/key: add MachinePrivate and MachinePublic.

Plumb throughout the codebase as a replacement for the mixed use of
tailcfg.MachineKey and wgkey.Private/Public.

Signed-off-by: David Anderson <danderson@tailscale.com>

types/persist/persist.go

@@ -8,6 +8,7 @@ package persist
 import (
 	"fmt"
 
+	"tailscale.com/types/key"
 	"tailscale.com/types/structs"
 	"tailscale.com/types/wgkey"
 )
@@ -28,7 +29,7 @@ type Persist struct {
 	// needed. This field should be considered read-only from GUI
 	// frontends. The real value should not be written back in
 	// this field, lest the frontend persist it to disk.
-	LegacyFrontendPrivateMachineKey wgkey.Private `json:"PrivateMachineKey"`
+	LegacyFrontendPrivateMachineKey key.MachinePrivate `json:"PrivateMachineKey"`
 
 	PrivateNodeKey    wgkey.Private
 	OldPrivateNodeKey wgkey.Private // needed to request key rotation
@@ -52,7 +53,10 @@ func (p *Persist) Equals(p2 *Persist) bool {
 }
 
 func (p *Persist) Pretty() string {
-	var mk, ok, nk wgkey.Key
+	var (
+		mk     key.MachinePublic
+		ok, nk wgkey.Key
+	)
 	if !p.LegacyFrontendPrivateMachineKey.IsZero() {
 		mk = p.LegacyFrontendPrivateMachineKey.Public()
 	}
@@ -69,5 +73,5 @@ func (p *Persist) Pretty() string {
 		return k.ShortString()
 	}
 	return fmt.Sprintf("Persist{lm=%v, o=%v, n=%v u=%#v}",
-		ss(mk), ss(ok), ss(nk), p.LoginName)
+		mk.ShortString(), ss(ok), ss(nk), p.LoginName)
 }

types/persist/persist_clone.go

@@ -7,6 +7,7 @@
 package persist
 
 import (
+	"tailscale.com/types/key"
 	"tailscale.com/types/structs"
 	"tailscale.com/types/wgkey"
 )
@@ -26,7 +27,7 @@ func (src *Persist) Clone() *Persist {
 //   tailscale.com/cmd/cloner -type Persist
 var _PersistNeedsRegeneration = Persist(struct {
 	_                               structs.Incomparable
-	LegacyFrontendPrivateMachineKey wgkey.Private
+	LegacyFrontendPrivateMachineKey key.MachinePrivate
 	PrivateNodeKey                  wgkey.Private
 	OldPrivateNodeKey               wgkey.Private
 	Provider                        string

types/persist/persist_test.go

@@ -8,6 +8,7 @@ import (
 	"reflect"
 	"testing"
 
+	"tailscale.com/types/key"
 	"tailscale.com/types/wgkey"
 )
 
@@ -34,6 +35,7 @@ func TestPersistEqual(t *testing.T) {
 		}
 		return k
 	}
+	m1 := key.NewMachine()
 	k1 := newPrivate()
 	tests := []struct {
 		a, b *Persist
@@ -45,13 +47,13 @@ func TestPersistEqual(t *testing.T) {
 		{&Persist{}, &Persist{}, true},
 
 		{
-			&Persist{LegacyFrontendPrivateMachineKey: k1},
-			&Persist{LegacyFrontendPrivateMachineKey: newPrivate()},
+			&Persist{LegacyFrontendPrivateMachineKey: m1},
+			&Persist{LegacyFrontendPrivateMachineKey: key.NewMachine()},
 			false,
 		},
 		{
-			&Persist{LegacyFrontendPrivateMachineKey: k1},
-			&Persist{LegacyFrontendPrivateMachineKey: k1},
+			&Persist{LegacyFrontendPrivateMachineKey: m1},
+			&Persist{LegacyFrontendPrivateMachineKey: m1},
 			true,
 		},