core: implement System.Contract.Call interop

pkg/core/interop/context.go

@@ -84,6 +84,16 @@ type ContractMD struct {
 	Methods     map[string]MethodAndPrice
 }
 
+// GetContract returns script of the contract with the specified hash.
+func (ic *Context) GetContract(h util.Uint160) ([]byte, bool) {
+	cs, err := ic.DAO.GetContractState(h)
+	if err != nil {
+		return nil, false
+	}
+	hasDynamicInvoke := (cs.Properties & smartcontract.HasDynamicInvoke) != 0
+	return cs.Script, hasDynamicInvoke
+}
+
 // NewContractMD returns Contract with the specified list of methods.
 func NewContractMD(name string) *ContractMD {
 	c := &ContractMD{

pkg/core/interop_system.go

@@ -11,6 +11,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
@@ -470,6 +471,39 @@ func storageContextAsReadOnly(ic *interop.Context, v *vm.VM) error {
 	return nil
 }
 
+// contractCall calls a contract.
+func contractCall(ic *interop.Context, v *vm.VM) error {
+	h := v.Estack().Pop().Bytes()
+	method := v.Estack().Pop().Item()
+	args := v.Estack().Pop().Item()
+	return contractCallExInternal(ic, v, h, method, args, smartcontract.All)
+}
+
+// contractCallEx calls a contract with flags.
+func contractCallEx(ic *interop.Context, v *vm.VM) error {
+	h := v.Estack().Pop().Bytes()
+	method := v.Estack().Pop().Item()
+	args := v.Estack().Pop().Item()
+	flags := smartcontract.CallFlag(int32(v.Estack().Pop().BigInt().Int64()))
+	return contractCallExInternal(ic, v, h, method, args, flags)
+}
+
+func contractCallExInternal(ic *interop.Context, v *vm.VM, h []byte, method vm.StackItem, args vm.StackItem, _ smartcontract.CallFlag) error {
+	u, err := util.Uint160DecodeBytesBE(h)
+	if err != nil {
+		return errors.New("invalid contract hash")
+	}
+	script, _ := ic.GetContract(u)
+	if script == nil {
+		return errors.New("contract not found")
+	}
+	// TODO perform flags checking after #923
+	v.LoadScript(script)
+	v.Estack().PushVal(args)
+	v.Estack().PushVal(method)
+	return nil
+}
+
 // contractDestroy destroys a contract.
 func contractDestroy(ic *interop.Context, v *vm.VM) error {
 	if ic.Trigger != trigger.Application {

pkg/core/interops.go

@@ -16,8 +16,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/iterator"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/core/native"
-	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
-	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 )
@@ -27,18 +25,7 @@ import (
 func SpawnVM(ic *interop.Context) *vm.VM {
 	vm := vm.New()
 	bc := ic.Chain.(*Blockchain)
-	vm.SetScriptGetter(func(hash util.Uint160) ([]byte, bool) {
+	vm.SetScriptGetter(ic.GetContract)
-		if c := bc.contracts.ByHash(hash); c != nil {
-			meta := c.Metadata()
-			return meta.Script, (meta.Manifest.Features&smartcontract.HasDynamicInvoke != 0)
-		}
-		cs, err := ic.DAO.GetContractState(hash)
-		if err != nil {
-			return nil, false
-		}
-		hasDynamicInvoke := (cs.Properties & smartcontract.HasDynamicInvoke) != 0
-		return cs.Script, hasDynamicInvoke
-	})
 	vm.RegisterInteropGetter(getSystemInterop(ic))
 	vm.RegisterInteropGetter(getNeoInterop(ic))
 	vm.RegisterInteropGetter(bc.contracts.GetNativeInterop(ic))
@@ -84,6 +71,8 @@ var systemInterops = []interop.Function{
 	{Name: "System.Blockchain.GetHeight", Func: bcGetHeight, Price: 1},
 	{Name: "System.Blockchain.GetTransaction", Func: bcGetTransaction, Price: 200},
 	{Name: "System.Blockchain.GetTransactionHeight", Func: bcGetTransactionHeight, Price: 100},
+	{Name: "System.Contract.Call", Func: contractCall, Price: 1},
+	{Name: "System.Contract.CallEx", Func: contractCallEx, Price: 1},
 	{Name: "System.Contract.Destroy", Func: contractDestroy, Price: 1},
 	{Name: "System.Contract.GetStorageContext", Func: contractGetStorageContext, Price: 1},
 	{Name: "System.ExecutionEngine.GetCallingScriptHash", Func: engineGetCallingScriptHash, Price: 1},

pkg/core/native_contract_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
@@ -85,6 +86,9 @@ func TestNativeContract_Invoke(t *testing.T) {
 	tn := newTestNative()
 	chain.registerNative(tn)
 
+	err := chain.dao.PutContractState(&state.Contract{Script: tn.meta.Script})
+	require.NoError(t, err)
+
 	w := io.NewBufBinWriter()
 	emit.AppCallWithOperationAndArgs(w.BinWriter, tn.Metadata().Hash, "sum", int64(14), int64(28))
 	script := w.Bytes()