core: verification script must return exactly one value

C# node is quite picky as it expects there to be exactly one value returned,
but our testchain actually adds 4 signatures for multisig cases instead of 3
which makes it technically incompatible with C# node.

pkg/core/blockchain.go

@@ -1490,6 +1490,9 @@ func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transa
 		if !resEl.Bool() {
 			return fmt.Errorf("%w: invalid signature", ErrVerificationFailed)
 		}
+		if vm.Estack().Len() != 0 {
+			return fmt.Errorf("%w: expected exactly one returned value", ErrVerificationFailed)
+		}
 		if useKeys {
 			bc.keyCacheLock.RLock()
 			_, ok := bc.keyCache[hash]

pkg/core/blockchain_test.go

@@ -354,6 +354,15 @@ func TestVerifyHashAgainstScript(t *testing.T) {
 		err := bc.verifyHashAgainstScript(hash.Hash160(verif), w, ic, false, gas)
 		require.True(t, errors.Is(err, ErrVerificationFailed))
 	})
+	t.Run("TooManyResults", func(t *testing.T) {
+		verif := []byte{byte(opcode.NOP)}
+		w := &transaction.Witness{
+			InvocationScript:   []byte{byte(opcode.PUSH1), byte(opcode.PUSH1)},
+			VerificationScript: verif,
+		}
+		err := bc.verifyHashAgainstScript(hash.Hash160(verif), w, ic, false, gas)
+		require.True(t, errors.Is(err, ErrVerificationFailed))
+	})
 }
 
 func TestHasBlock(t *testing.T) {

pkg/internal/testchain/address.go

@@ -84,7 +84,7 @@ func MultisigAddress() string {
 // Sign signs data by all consensus nodes and returns invocation script.
 func Sign(data []byte) []byte {
 	buf := io.NewBufBinWriter()
-	for i := 0; i < Size(); i++ {
+	for i := 0; i < 3; i++ {
 		pKey := PrivateKey(i)
 		sig := pKey.Sign(data)
 		if len(sig) != 64 {

pkg/rpc/server/server_test.go

@@ -52,8 +52,8 @@ type rpcTestCase struct {
 	check  func(t *testing.T, e *executor, result interface{})
 }
 
-const testContractHash = "5b5f77b947194ba45ff5fa1ba6e066af5636d110"
+const testContractHash = "93c4983afe01a75f74c1e56011bd630e9d8cc755"
-const deploymentTxHash = "af0f94f6bdc5aada7abf1db19f1fcd2ea56cea596c41dc4abdfa6cd9664a7d72"
+const deploymentTxHash = "583cf0e49d69d8854869efc3e97ad741061da478292a7280580789351a39a1ac"
 
 var rpcTestCases = map[string][]rpcTestCase{
 	"getapplicationlog": {
@@ -1027,7 +1027,7 @@ func checkNep5Balances(t *testing.T, e *executor, acc interface{}) {
 			},
 			{
 				Asset:       e.chain.UtilityTokenHash(),
-				Amount:      "915.61054740",
+				Amount:      "915.61059740",
 				LastUpdated: 6,
 			}},
 		Address: testchain.PrivateKeyByID(0).GetScriptHash().StringLE(),