core: implement System.Contract.IsStandard syscall

pkg/core/interop_system.go

@@ -470,3 +470,19 @@ func contractDestroy(ic *interop.Context, v *vm.VM) error {
 	}
 	return nil
 }
+
+// contractIsStandard checks if contract is standard (sig or multisig) contract.
+func contractIsStandard(ic *interop.Context, v *vm.VM) error {
+	h := v.Estack().Pop().Bytes()
+	u, err := util.Uint160DecodeBytesBE(h)
+	if err != nil {
+		return err
+	}
+	var result bool
+	cs, _ := ic.DAO.GetContractState(u)
+	if cs == nil || vm.IsStandardContract(cs.Script) {
+		result = true
+	}
+	v.Estack().PushVal(result)
+	return nil
+}

pkg/core/interop_system_test.go

@@ -4,6 +4,10 @@ import (
 	"math/big"
 	"testing"
 
+	"github.com/nspcc-dev/dbft/crypto"
+	"github.com/nspcc-dev/neo-go/pkg/core/state"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
+	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/stretchr/testify/require"
 )
@@ -145,3 +149,29 @@ func TestBCGetBlock(t *testing.T) {
 		require.True(t, ok)
 	})
 }
+
+func TestContractIsStandard(t *testing.T) {
+	v, ic, chain := createVM(t)
+	defer chain.Close()
+
+	t.Run("True", func(t *testing.T) {
+		priv, err := keys.NewPrivateKey()
+		require.NoError(t, err)
+
+		pub := priv.PublicKey()
+		err = ic.DAO.PutContractState(&state.Contract{ID: 42, Script: pub.GetVerificationScript()})
+		require.NoError(t, err)
+
+		v.Estack().PushVal(pub.GetScriptHash().BytesBE())
+		require.NoError(t, contractIsStandard(ic, v))
+		require.True(t, v.Estack().Pop().Bool())
+	})
+	t.Run("False", func(t *testing.T) {
+		script := []byte{byte(opcode.PUSHT)}
+		require.NoError(t, ic.DAO.PutContractState(&state.Contract{ID: 24, Script: script}))
+
+		v.Estack().PushVal(crypto.Hash160(script).BytesBE())
+		require.NoError(t, contractIsStandard(ic, v))
+		require.False(t, v.Estack().Pop().Bool())
+	})
+}

pkg/core/interops.go

@@ -91,6 +91,7 @@ var systemInterops = []interop.Function{
 		AllowedTriggers: trigger.Application, RequiredFlags: smartcontract.AllowModifyStates},
 	{Name: "System.Contract.Destroy", Func: contractDestroy, Price: 1000000,
 		AllowedTriggers: trigger.Application, RequiredFlags: smartcontract.AllowModifyStates},
+	{Name: "System.Contract.IsStandard", Func: contractIsStandard, Price: 30000},
 	{Name: "System.Contract.Update", Func: contractUpdate, Price: 0,
 		AllowedTriggers: trigger.Application, RequiredFlags: smartcontract.AllowModifyStates},
 	{Name: "System.Enumerator.Concat", Func: enumerator.Concat, Price: 400},