manifest: don't accept manifests with invalid features

Refs. #3522.

Signed-off-by: Roman Khimov <roman@nspcc.ru>

cli/smartcontract/testdata/verify.manifest.json

@@ -1 +1 @@
-{"name":"verify","abi":{"methods":[{"name":"verify","offset":0,"parameters":[],"returntype":"Boolean","safe":false},{"name":"onNEP17Payment","offset":5,"parameters":[{"name":"from","type":"ByteArray"},{"name":"amount","type":"Integer"},{"name":"data","type":"Any"}],"returntype":"Void","safe":false}],"events":[{"name":"Hello world!","parameters":[{"name":"args","type":"Array"}]}]},"groups":[],"permissions":[{"contract":"*","methods":"*"}],"supportedstandards":[],"trusts":[],"extra":null}
+{"name":"verify","abi":{"methods":[{"name":"verify","offset":0,"parameters":[],"returntype":"Boolean","safe":false},{"name":"onNEP17Payment","offset":5,"parameters":[{"name":"from","type":"ByteArray"},{"name":"amount","type":"Integer"},{"name":"data","type":"Any"}],"returntype":"Void","safe":false}],"events":[{"name":"Hello world!","parameters":[{"name":"args","type":"Array"}]}]},"groups":[],"permissions":[{"contract":"*","methods":"*"}],"supportedstandards":[],"trusts":[],"extra":null,"features":{}}

cli/smartcontract/testdata/verifyrpc/verify.manifest.json

@@ -4,6 +4,7 @@
    "supportedstandards" : [],
    "name" : "verify",
    "trusts" : [],
+   "features": {},
    "permissions" : [
       {
          "methods" : "*",

pkg/core/interop/runtime/ext_test.go

@@ -713,6 +713,7 @@ func TestSystemRuntimeNotify_HFBasilisk(t *testing.T) {
 
 	m := &manifest.Manifest{
 		Name:     "ctr",
+		Features: json.RawMessage("{}"),
 		Groups:   []manifest.Group{},
 		ABI: manifest.ABI{
 			Methods: []manifest.Method{

pkg/core/native/management_neotest_test.go

@@ -53,6 +53,7 @@ func TestManagement_DeployUpdate_HFBasilisk(t *testing.T) {
 
 	m := &manifest.Manifest{
 		Name:     "ctr",
+		Features: json.RawMessage("{}"),
 		Groups:   []manifest.Group{},
 		ABI: manifest.ABI{
 			Methods: []manifest.Method{
@@ -89,6 +90,7 @@ func TestManagement_CallInTheSameBlock(t *testing.T) {
 
 	m := &manifest.Manifest{
 		Name:     "ctr",
+		Features: json.RawMessage("{}"),
 		Groups:   []manifest.Group{},
 		ABI: manifest.ABI{
 			Methods: []manifest.Method{

pkg/smartcontract/manifest/manifest.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"strings"
 
 	ojson "github.com/nspcc-dev/go-ordered-json"
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -24,6 +25,8 @@ const (
 	NEP11Payable = "NEP-11-Payable"
 	// NEP17Payable represents the name of contract interface which can receive NEP-17 tokens.
 	NEP17Payable = "NEP-17-Payable"
+
+	emptyFeatures = "{}"
 )
 
 // Manifest represens contract metadata.
@@ -53,7 +56,7 @@ func NewManifest(name string) *Manifest {
 			Methods: []Method{},
 			Events:  []Event{},
 		},
-		Features:           json.RawMessage("{}"),
+		Features:           json.RawMessage(emptyFeatures),
 		Groups:             []Group{},
 		Permissions:        []Permission{},
 		SupportedStandards: []string{},
@@ -107,6 +110,16 @@ func (m *Manifest) IsValid(hash util.Uint160, checkSize bool) error {
 	if err != nil {
 		return fmt.Errorf("ABI: %w", err)
 	}
+
+	if strings.Map(func(c rune) rune {
+		switch c {
+		case ' ', '\n', '\t', '\r': // Strip all JSON whitespace.
+			return -1
+		}
+		return c
+	}, string(m.Features)) != emptyFeatures { // empty struct should be left.
+		return errors.New("invalid features")
+	}
 	err = Groups(m.Groups).AreValid(hash)
 	if err != nil {
 		return err
@@ -235,7 +248,7 @@ func (m *Manifest) FromStackItem(item stackitem.Item) error {
 	if str[2].Type() != stackitem.MapT || str[2].(*stackitem.Map).Len() != 0 {
 		return errors.New("invalid Features stackitem")
 	}
-	m.Features = json.RawMessage("{}")
+	m.Features = json.RawMessage(emptyFeatures)
 	if str[3].Type() != stackitem.ArrayT {
 		return errors.New("invalid SupportedStandards stackitem type")
 	}

pkg/smartcontract/manifest/manifest_test.go

@@ -144,6 +144,24 @@ func TestIsValid(t *testing.T) {
 		require.NoError(t, m.IsValid(contractHash, true))
 	})
 
+	t.Run("invalid, no features", func(t *testing.T) {
+		m.Features = nil
+		require.Error(t, m.IsValid(contractHash, true))
+	})
+	m.Features = json.RawMessage(emptyFeatures)
+
+	t.Run("invalid, bad features", func(t *testing.T) {
+		m.Features = json.RawMessage(`{ "v" : true}`)
+		require.Error(t, m.IsValid(contractHash, true))
+	})
+	m.Features = json.RawMessage(emptyFeatures)
+
+	t.Run("valid, features with spaces", func(t *testing.T) {
+		m.Features = json.RawMessage("{ \t\n\r }")
+		require.NoError(t, m.IsValid(contractHash, true))
+	})
+	m.Features = json.RawMessage(emptyFeatures)
+
 	m.ABI.Events = append(m.ABI.Events, Event{
 		Name:       "itHappened",
 		Parameters: []Parameter{},