tailcfg: don't panic on node equal check

Signed-off-by: wardn <wardn@users.noreply.github.com>

tailcfg/tailcfg.go

@@ -6,9 +6,9 @@
 
 import (
 	"bytes"
-	"encoding/json"
 	"errors"
 	"fmt"
+	"reflect"
 	"strings"
 	"time"
 
@@ -345,15 +345,23 @@ func (id GroupID) String() string      { return fmt.Sprintf("groupid:%x", int64(
 func (id RoleID) String() string       { return fmt.Sprintf("roleid:%x", int64(id)) }
 func (id CapabilityID) String() string { return fmt.Sprintf("capid:%x", int64(id)) }
 
+// Equal reports whether n and n2 are equal.
 func (n *Node) Equal(n2 *Node) bool {
-	// TODO(crawshaw): this is crude, but is an easy way to avoid bugs.
-	b, err := json.Marshal(n)
-	if err != nil {
-		panic(err)
+	if n == nil && n2 == nil {
+		return true
 	}
-	b2, err := json.Marshal(n2)
-	if err != nil {
-		panic(err)
-	}
-	return bytes.Equal(b, b2)
+	return n != nil && n2 != nil &&
+		n.ID == n2.ID &&
+		n.Name == n2.Name &&
+		n.User == n2.User &&
+		n.Key == n2.Key &&
+		n.KeyExpiry.Equal(n2.KeyExpiry) &&
+		n.Machine == n2.Machine &&
+		reflect.DeepEqual(n.Addresses, n2.Addresses) &&
+		reflect.DeepEqual(n.AllowedIPs, n2.AllowedIPs) &&
+		reflect.DeepEqual(n.Endpoints, n2.Endpoints) &&
+		reflect.DeepEqual(n.Hostinfo, n2.Hostinfo) &&
+		n.Created.Equal(n2.Created) &&
+		reflect.DeepEqual(n.LastSeen, n2.LastSeen) &&
+		n.MachineAuthorized == n2.MachineAuthorized
 }

tailcfg/tailcfg_test.go

@@ -0,0 +1,166 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tailcfg
+
+import (
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/tailscale/wireguard-go/wgcfg"
+)
+
+func fieldsOf(t reflect.Type) (fields []string) {
+	for i := 0; i < t.NumField(); i++ {
+		fields = append(fields, t.Field(i).Name)
+	}
+	return
+}
+
+func TestNodeEqual(t *testing.T) {
+	nodeHandles := []string{"ID", "Name", "User", "Key", "KeyExpiry", "Machine", "Addresses", "AllowedIPs", "Endpoints", "Hostinfo", "Created", "LastSeen", "MachineAuthorized"}
+	if have := fieldsOf(reflect.TypeOf(Node{})); !reflect.DeepEqual(have, nodeHandles) {
+		t.Errorf("Node.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
+			have, nodeHandles)
+	}
+
+	newPublicKey := func(t *testing.T) wgcfg.Key {
+		t.Helper()
+		k, err := wgcfg.NewPrivateKey()
+		if err != nil {
+			t.Fatal(err)
+		}
+		return k.Public()
+	}
+	n1 := newPublicKey(t)
+	now := time.Now()
+
+	tests := []struct {
+		a, b *Node
+		want bool
+	}{
+		{
+			&Node{},
+			nil,
+			false,
+		},
+		{
+			nil,
+			&Node{},
+			false,
+		},
+		{
+			&Node{},
+			&Node{},
+			true,
+		},
+		{
+			&Node{User: 0},
+			&Node{User: 1},
+			false,
+		},
+		{
+			&Node{User: 1},
+			&Node{User: 1},
+			true,
+		},
+		{
+			&Node{Key: NodeKey(n1)},
+			&Node{Key: NodeKey(newPublicKey(t))},
+			false,
+		},
+		{
+			&Node{Key: NodeKey(n1)},
+			&Node{Key: NodeKey(n1)},
+			true,
+		},
+		{
+			&Node{KeyExpiry: now},
+			&Node{KeyExpiry: now.Add(60 * time.Second)},
+			false,
+		},
+		{
+			&Node{KeyExpiry: now},
+			&Node{KeyExpiry: now},
+			true,
+		},
+		{
+			&Node{Machine: MachineKey(n1)},
+			&Node{Machine: MachineKey(newPublicKey(t))},
+			false,
+		},
+		{
+			&Node{Machine: MachineKey(n1)},
+			&Node{Machine: MachineKey(n1)},
+			true,
+		},
+		{
+			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: nil},
+			false,
+		},
+		{
+			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: []wgcfg.CIDR{}},
+			true,
+		},
+		{
+			&Node{AllowedIPs: []wgcfg.CIDR{}},
+			&Node{AllowedIPs: nil},
+			false,
+		},
+		{
+			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: []wgcfg.CIDR{}},
+			true,
+		},
+		{
+			&Node{Endpoints: []string{}},
+			&Node{Endpoints: nil},
+			false,
+		},
+		{
+			&Node{Endpoints: []string{}},
+			&Node{Endpoints: []string{}},
+			true,
+		},
+		{
+			&Node{Hostinfo: Hostinfo{Hostname: "alice"}},
+			&Node{Hostinfo: Hostinfo{Hostname: "bob"}},
+			false,
+		},
+		{
+			&Node{Hostinfo: Hostinfo{}},
+			&Node{Hostinfo: Hostinfo{}},
+			true,
+		},
+		{
+			&Node{Created: now},
+			&Node{Created: now.Add(60 * time.Second)},
+			false,
+		},
+		{
+			&Node{Created: now},
+			&Node{Created: now},
+			true,
+		},
+		{
+			&Node{LastSeen: &now},
+			&Node{LastSeen: nil},
+			false,
+		},
+		{
+			&Node{LastSeen: &now},
+			&Node{LastSeen: &now},
+			true,
+		},
+	}
+	for i, tt := range tests {
+		got := tt.a.Equal(tt.b)
+		if got != tt.want {
+			t.Errorf("%d. Equal = %v; want %v", i, got, tt.want)
+		}
+	}
+}