Merge pull request #1238 from nspcc-dev/feature/callback

Implement `System.Callback.*` interops

pkg/compiler/panic_test.go

@@ -1,6 +1,7 @@
 package compiler_test
 
 import (
+	"errors"
 	"fmt"
 	"math/big"
 	"testing"
@@ -20,7 +21,7 @@ func TestPanic(t *testing.T) {
 		var logs []string
 		src := getPanicSource(true, `"execution fault"`)
 		v := vmAndCompile(t, src)
-		v.RegisterInteropGetter(logGetter(&logs))
+		v.SyscallHandler = getLogHandler(&logs)
 
 		require.Error(t, v.Run())
 		require.True(t, v.HasFailed())
@@ -32,7 +33,7 @@ func TestPanic(t *testing.T) {
 		var logs []string
 		src := getPanicSource(true, `nil`)
 		v := vmAndCompile(t, src)
-		v.RegisterInteropGetter(logGetter(&logs))
+		v.SyscallHandler = getLogHandler(&logs)
 
 		require.Error(t, v.Run())
 		require.True(t, v.HasFailed())
@@ -54,19 +55,15 @@ func getPanicSource(need bool, message string) string {
 	`, need, message)
 }
 
-func logGetter(logs *[]string) vm.InteropGetterFunc {
+func getLogHandler(logs *[]string) vm.SyscallHandler {
 	logID := emit.InteropNameToID([]byte("System.Runtime.Log"))
-	return func(id uint32) *vm.InteropFuncPrice {
+	return func(v *vm.VM, id uint32) error {
 		if id != logID {
-			return nil
+			return errors.New("syscall not found")
 		}
 
-		return &vm.InteropFuncPrice{
-			Func: func(v *vm.VM) error {
 		msg := string(v.Estack().Pop().Bytes())
 		*logs = append(*logs, msg)
 		return nil
-			},
-		}
 	}
 }

pkg/compiler/util_test.go

@@ -23,7 +23,8 @@ func TestSHA256(t *testing.T) {
 	`
 	v := vmAndCompile(t, src)
 	ic := &interop.Context{Trigger: trigger.Verification}
-	v.RegisterInteropGetter(crypto.GetInterop(ic))
+	crypto.Register(ic)
+	v.SyscallHandler = ic.SyscallHandler
 	require.NoError(t, v.Run())
 	require.True(t, v.Estack().Len() >= 1)
 

pkg/compiler/vm_test.go

@@ -1,6 +1,7 @@
 package compiler_test
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"testing"
@@ -68,7 +69,8 @@ func vmAndCompileInterop(t *testing.T, src string) (*vm.VM, *storagePlugin) {
 	vm := vm.New()
 
 	storePlugin := newStoragePlugin()
-	vm.RegisterInteropGetter(storePlugin.getInterop)
+	vm.GasLimit = -1
+	vm.SyscallHandler = storePlugin.syscallHandler
 
 	b, di, err := compiler.CompileWithDebugInfo(strings.NewReader(src))
 	require.NoError(t, err)
@@ -97,14 +99,14 @@ func invokeMethod(t *testing.T, method string, script []byte, v *vm.VM, di *comp
 
 type storagePlugin struct {
 	mem      map[string][]byte
-	interops map[uint32]vm.InteropFunc
+	interops map[uint32]func(v *vm.VM) error
 	events   []state.NotificationEvent
 }
 
 func newStoragePlugin() *storagePlugin {
 	s := &storagePlugin{
 		mem:      make(map[string][]byte),
-		interops: make(map[uint32]vm.InteropFunc),
+		interops: make(map[uint32]func(v *vm.VM) error),
 	}
 	s.interops[emit.InteropNameToID([]byte("System.Storage.Get"))] = s.Get
 	s.interops[emit.InteropNameToID([]byte("System.Storage.Put"))] = s.Put
@@ -114,12 +116,15 @@ func newStoragePlugin() *storagePlugin {
 
 }
 
-func (s *storagePlugin) getInterop(id uint32) *vm.InteropFuncPrice {
+func (s *storagePlugin) syscallHandler(v *vm.VM, id uint32) error {
 	f := s.interops[id]
 	if f != nil {
-		return &vm.InteropFuncPrice{Func: f, Price: 1}
+		if !v.AddGas(1) {
+			return errors.New("insufficient amount of gas")
 		}
-	return nil
+		return f(v)
+	}
+	return errors.New("syscall not found")
 }
 
 func (s *storagePlugin) Notify(v *vm.VM) error {

pkg/consensus/payload.go

@@ -11,8 +11,8 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"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"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/pkg/errors"
 )
@@ -222,9 +222,10 @@ func (p *Payload) Verify(scriptHash util.Uint160) bool {
 		return false
 	}
 
-	v := vm.New()
+	ic := &interop.Context{Trigger: trigger.Verification, Container: p}
+	crypto.Register(ic)
+	v := ic.SpawnVM()
 	v.GasLimit = payloadGasLimit
-	v.RegisterInteropGetter(crypto.GetInterop(&interop.Context{Container: p}))
 	v.LoadScript(verification)
 	v.LoadScript(p.Witness.InvocationScript)
 

pkg/core/blockchain.go

@@ -566,8 +566,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 
 	if block.Index > 0 {
 		systemInterop := bc.newInteropContext(trigger.System, cache, block, nil)
-		v := SpawnVM(systemInterop)
+		v := systemInterop.SpawnVM()
-		v.GasLimit = -1
 		v.LoadScriptWithFlags(bc.contracts.GetPersistScript(), smartcontract.AllowModifyStates|smartcontract.AllowCall)
 		v.SetPriceGetter(getPrice)
 		if err := v.Run(); err != nil {
@@ -599,7 +598,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 		}
 
 		systemInterop := bc.newInteropContext(trigger.Application, cache, block, tx)
-		v := SpawnVM(systemInterop)
+		v := systemInterop.SpawnVM()
 		v.LoadScriptWithFlags(tx.Script, smartcontract.All)
 		v.SetPriceGetter(getPrice)
 		v.GasLimit = tx.SystemFee
@@ -1277,7 +1276,7 @@ func (bc *Blockchain) GetScriptHashesForVerifying(t *transaction.Transaction) ([
 // GetTestVM returns a VM and a Store setup for a test run of some sort of code.
 func (bc *Blockchain) GetTestVM(tx *transaction.Transaction) *vm.VM {
 	systemInterop := bc.newInteropContext(trigger.Application, bc.dao, nil, tx)
-	vm := SpawnVM(systemInterop)
+	vm := systemInterop.SpawnVM()
 	vm.SetPriceGetter(getPrice)
 	return vm
 }
@@ -1310,7 +1309,7 @@ func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transa
 		gas = gasPolicy
 	}
 
-	vm := SpawnVM(interopCtx)
+	vm := interopCtx.SpawnVM()
 	vm.SetPriceGetter(getPrice)
 	vm.GasLimit = gas
 	vm.LoadScriptWithFlags(verification, smartcontract.ReadOnly)
@@ -1413,6 +1412,7 @@ func (bc *Blockchain) secondsPerBlock() int {
 
 func (bc *Blockchain) newInteropContext(trigger trigger.Type, d dao.DAO, block *block.Block, tx *transaction.Transaction) *interop.Context {
 	ic := interop.NewContext(trigger, bc, d, bc.contracts.Contracts, block, tx, bc.log)
+	ic.Functions = [][]interop.Function{systemInterops, neoInterops}
 	switch {
 	case tx != nil:
 		ic.Container = tx

pkg/core/gas_price.go

@@ -9,14 +9,6 @@ import (
 const StoragePrice = 100000
 
 // getPrice returns a price for executing op with the provided parameter.
-// Some SYSCALLs have variable price depending on their arguments.
 func getPrice(v *vm.VM, op opcode.Opcode, parameter []byte) int64 {
-	if op == opcode.SYSCALL {
-		interopID := vm.GetInteropID(parameter)
-		ifunc := v.GetInteropByID(interopID)
-		if ifunc != nil && ifunc.Price > 0 {
-			return ifunc.Price
-		}
-	}
 	return opcodePrice(op)
 }

pkg/core/interop/callback/callback.go

@@ -0,0 +1,37 @@
+package callback
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// Callback is an interface for arbitrary callbacks.
+type Callback interface {
+	// ArgCount returns expected number of arguments.
+	ArgCount() int
+	// LoadContext loads context and arguments on stack.
+	LoadContext(*vm.VM, []stackitem.Item)
+}
+
+// Invoke invokes provided callback.
+func Invoke(ic *interop.Context, v *vm.VM) error {
+	cb := v.Estack().Pop().Interop().Value().(Callback)
+	args := v.Estack().Pop().Array()
+	if cb.ArgCount() != len(args) {
+		return errors.New("invalid argument count")
+	}
+	cb.LoadContext(v, args)
+	switch t := cb.(type) {
+	case *MethodCallback:
+		id := emit.InteropNameToID([]byte("System.Contract.Call"))
+		return ic.SyscallHandler(v, id)
+	case *SyscallCallback:
+		return ic.SyscallHandler(v, t.desc.ID)
+	default:
+		return nil
+	}
+}

pkg/core/interop/callback/method.go

@@ -0,0 +1,60 @@
+package callback
+
+import (
+	"errors"
+	"strings"
+
+	"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/smartcontract/manifest"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// MethodCallback represents callback for contract method.
+type MethodCallback struct {
+	contract *state.Contract
+	method   *manifest.Method
+}
+
+var _ Callback = (*MethodCallback)(nil)
+
+// ArgCount implements Callback interface.
+func (s *MethodCallback) ArgCount() int {
+	return len(s.method.Parameters)
+}
+
+// LoadContext implements Callback interface.
+func (s *MethodCallback) LoadContext(v *vm.VM, args []stackitem.Item) {
+	v.Estack().PushVal(args)
+	v.Estack().PushVal(s.method.Name)
+	v.Estack().PushVal(s.contract.ScriptHash().BytesBE())
+}
+
+// CreateFromMethod creates callback for a contract method.
+func CreateFromMethod(ic *interop.Context, v *vm.VM) error {
+	rawHash := v.Estack().Pop().Bytes()
+	h, err := util.Uint160DecodeBytesBE(rawHash)
+	if err != nil {
+		return err
+	}
+	cs, err := ic.DAO.GetContractState(h)
+	if err != nil {
+		return errors.New("contract not found")
+	}
+	method := string(v.Estack().Pop().Bytes())
+	if strings.HasPrefix(method, "_") {
+		return errors.New("invalid method name")
+	}
+	currCs, err := ic.DAO.GetContractState(v.GetCurrentScriptHash())
+	if err == nil && !currCs.Manifest.CanCall(&cs.Manifest, method) {
+		return errors.New("method call is not allowed")
+	}
+	md := cs.Manifest.ABI.GetMethod(method)
+	v.Estack().PushVal(stackitem.NewInterop(&MethodCallback{
+		contract: cs,
+		method:   md,
+	}))
+	return nil
+}

pkg/core/interop/callback/pointer.go

@@ -0,0 +1,42 @@
+package callback
+
+import (
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// PointerCallback represents callback for a pointer.
+type PointerCallback struct {
+	paramCount int
+	offset     int
+	context    *vm.Context
+}
+
+var _ Callback = (*PointerCallback)(nil)
+
+// ArgCount implements Callback interface.
+func (p *PointerCallback) ArgCount() int {
+	return p.paramCount
+}
+
+// LoadContext implements Callback interface.
+func (p *PointerCallback) LoadContext(v *vm.VM, args []stackitem.Item) {
+	v.Call(p.context, p.offset)
+	for i := len(args) - 1; i >= 0; i-- {
+		v.Estack().PushVal(args[i])
+	}
+}
+
+// Create creates callback using pointer and parameters count.
+func Create(_ *interop.Context, v *vm.VM) error {
+	ctx := v.Estack().Pop().Item().(*vm.Context)
+	offset := v.Estack().Pop().Item().(*stackitem.Pointer).Position()
+	count := v.Estack().Pop().BigInt().Int64()
+	v.Estack().PushVal(stackitem.NewInterop(&PointerCallback{
+		paramCount: int(count),
+		offset:     offset,
+		context:    ctx,
+	}))
+	return nil
+}

pkg/core/interop/callback/syscall.go

@@ -0,0 +1,42 @@
+package callback
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// SyscallCallback represents callback for a syscall.
+type SyscallCallback struct {
+	desc *interop.Function
+}
+
+var _ Callback = (*SyscallCallback)(nil)
+
+// ArgCount implements Callback interface.
+func (p *SyscallCallback) ArgCount() int {
+	return p.desc.ParamCount
+}
+
+// LoadContext implements Callback interface.
+func (p *SyscallCallback) LoadContext(v *vm.VM, args []stackitem.Item) {
+	for i := len(args) - 1; i >= 0; i-- {
+		v.Estack().PushVal(args[i])
+	}
+}
+
+// CreateFromSyscall creates callback from syscall.
+func CreateFromSyscall(ic *interop.Context, v *vm.VM) error {
+	id := uint32(v.Estack().Pop().BigInt().Int64())
+	f := ic.GetFunction(id)
+	if f == nil {
+		return errors.New("syscall not found")
+	}
+	if f.DisallowCallback {
+		return errors.New("syscall is not allowed to be used in a callback")
+	}
+	v.Estack().PushVal(stackitem.NewInterop(&SyscallCallback{f}))
+	return nil
+}

pkg/core/interop/context.go

@@ -1,6 +1,10 @@
 package interop
 
 import (
+	"errors"
+	"fmt"
+	"sort"
+
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
 	"github.com/nspcc-dev/neo-go/pkg/core/dao"
@@ -32,6 +36,7 @@ type Context struct {
 	Log           *zap.Logger
 	Invocations   map[util.Uint160]int
 	ScriptGetter  vm.ScriptHashGetter
+	Functions     [][]Function
 }
 
 // NewContext returns new interop context.
@@ -48,6 +53,8 @@ func NewContext(trigger trigger.Type, bc blockchainer.Blockchainer, d dao.DAO, n
 		Notifications: nes,
 		Log:           log,
 		Invocations:   make(map[util.Uint160]int),
+		// Functions is a slice of slices of interops sorted by ID.
+		Functions: [][]Function{},
 	}
 }
 
@@ -58,6 +65,10 @@ type Function struct {
 	ID   uint32
 	Name string
 	Func func(*Context, *vm.VM) error
+	// DisallowCallback is true iff syscall can't be used in a callback.
+	DisallowCallback bool
+	// ParamCount is a number of function parameters.
+	ParamCount int
 	Price      int64
 	// RequiredFlags is a set of flags which must be set during script invocations.
 	// Default value is NoneFlag i.e. no flags are required.
@@ -124,3 +135,46 @@ func (c *ContractMD) AddEvent(name string, ps ...manifest.Parameter) {
 		Parameters: ps,
 	})
 }
+
+// Sort sorts interop functions by id.
+func Sort(fs []Function) {
+	sort.Slice(fs, func(i, j int) bool { return fs[i].ID < fs[j].ID })
+}
+
+// GetFunction returns metadata for interop with the specified id.
+func (ic *Context) GetFunction(id uint32) *Function {
+	for _, slice := range ic.Functions {
+		n := sort.Search(len(slice), func(i int) bool {
+			return slice[i].ID >= id
+		})
+		if n < len(slice) && slice[n].ID == id {
+			return &slice[n]
+		}
+	}
+	return nil
+}
+
+// SyscallHandler handles syscall with id.
+func (ic *Context) SyscallHandler(v *vm.VM, id uint32) error {
+	f := ic.GetFunction(id)
+	if f == nil {
+		return errors.New("syscall not found")
+	}
+	cf := v.Context().GetCallFlags()
+	if !cf.Has(f.RequiredFlags) {
+		return fmt.Errorf("missing call flags: %05b vs %05b", cf, f.RequiredFlags)
+	}
+	if !v.AddGas(f.Price) {
+		return errors.New("insufficient amount of gas")
+	}
+	return f.Func(ic, v)
+}
+
+// SpawnVM spawns new VM with the specified gas limit.
+func (ic *Context) SpawnVM() *vm.VM {
+	v := vm.NewWithTrigger(ic.Trigger)
+	v.GasLimit = -1
+	v.SyscallHandler = ic.SyscallHandler
+	ic.ScriptGetter = v
+	return v
+}

pkg/core/interop/crypto/ecdsa_test.go

@@ -59,10 +59,9 @@ func initCHECKMULTISIGVM(t *testing.T, n int, ik, is []int) *vm.VM {
 	buf[0] = byte(opcode.SYSCALL)
 	binary.LittleEndian.PutUint32(buf[1:], ecdsaSecp256r1CheckMultisigID)
 
-	v := vm.New()
-	v.GasLimit = -1
 	ic := &interop.Context{Trigger: trigger.Verification}
-	v.RegisterInteropGetter(GetInterop(ic))
+	Register(ic)
+	v := ic.SpawnVM()
 	v.LoadScript(buf)
 	msg := []byte("NEO - An Open Network For Smart Economy")
 

pkg/core/interop/crypto/hash_test.go

@@ -7,7 +7,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
-	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -20,9 +19,9 @@ func TestSHA256(t *testing.T) {
 	emit.Bytes(buf.BinWriter, []byte{1, 0})
 	emit.Syscall(buf.BinWriter, "Neo.Crypto.SHA256")
 	prog := buf.Bytes()
-	v := vm.New()
 	ic := &interop.Context{Trigger: trigger.Verification}
-	v.RegisterInteropGetter(GetInterop(ic))
+	Register(ic)
+	v := ic.SpawnVM()
 	v.Load(prog)
 	require.NoError(t, v.Run())
 	assert.Equal(t, 1, v.Estack().Len())
@@ -36,9 +35,9 @@ func TestRIPEMD160(t *testing.T) {
 	emit.Bytes(buf.BinWriter, []byte{1, 0})
 	emit.Syscall(buf.BinWriter, "Neo.Crypto.RIPEMD160")
 	prog := buf.Bytes()
-	v := vm.New()
 	ic := &interop.Context{Trigger: trigger.Verification}
-	v.RegisterInteropGetter(GetInterop(ic))
+	Register(ic)
+	v := ic.SpawnVM()
 	v.Load(prog)
 	require.NoError(t, v.Run())
 	assert.Equal(t, 1, v.Estack().Len())

pkg/core/interop/crypto/interop.go

@@ -2,47 +2,32 @@ package crypto
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
-	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 )
 
 var (
 	ecdsaSecp256r1VerifyID        = emit.InteropNameToID([]byte("Neo.Crypto.VerifyWithECDsaSecp256r1"))
+	ecdsaSecp256k1VerifyID        = emit.InteropNameToID([]byte("Neo.Crypto.VerifyWithECDsaSecp256k1"))
 	ecdsaSecp256r1CheckMultisigID = emit.InteropNameToID([]byte("Neo.Crypto.CheckMultisigWithECDsaSecp256r1"))
+	ecdsaSecp256k1CheckMultisigID = emit.InteropNameToID([]byte("Neo.Crypto.CheckMultisigWithECDsaSecp256k1"))
 	sha256ID                      = emit.InteropNameToID([]byte("Neo.Crypto.SHA256"))
 	ripemd160ID                   = emit.InteropNameToID([]byte("Neo.Crypto.RIPEMD160"))
 )
 
-// GetInterop returns interop getter for crypto-related stuff.
+var cryptoInterops = []interop.Function{
-func GetInterop(ic *interop.Context) func(uint32) *vm.InteropFuncPrice {
+	{ID: ecdsaSecp256r1VerifyID, Func: ECDSASecp256r1Verify},
-	return func(id uint32) *vm.InteropFuncPrice {
+	{ID: ecdsaSecp256k1VerifyID, Func: ECDSASecp256k1Verify},
-		switch id {
+	{ID: ecdsaSecp256r1CheckMultisigID, Func: ECDSASecp256r1CheckMultisig},
-		case ecdsaSecp256r1VerifyID:
+	{ID: ecdsaSecp256k1CheckMultisigID, Func: ECDSASecp256k1CheckMultisig},
-			return &vm.InteropFuncPrice{
+	{ID: sha256ID, Func: Sha256},
-				Func: func(v *vm.VM) error {
+	{ID: ripemd160ID, Func: RipeMD160},
-					return ECDSASecp256r1Verify(ic, v)
+}
-				},
+
-			}
+func init() {
-		case ecdsaSecp256r1CheckMultisigID:
+	interop.Sort(cryptoInterops)
-			return &vm.InteropFuncPrice{
+}
-				Func: func(v *vm.VM) error {
+
-					return ECDSASecp256r1CheckMultisig(ic, v)
+// Register adds crypto interops to ic.
-				},
+func Register(ic *interop.Context) {
-			}
+	ic.Functions = append(ic.Functions, cryptoInterops)
-		case sha256ID:
-			return &vm.InteropFuncPrice{
-				Func: func(v *vm.VM) error {
-					return Sha256(ic, v)
-				},
-			}
-		case ripemd160ID:
-			return &vm.InteropFuncPrice{
-				Func: func(v *vm.VM) error {
-					return RipeMD160(ic, v)
-				},
-			}
-		default:
-			return nil
-		}
-	}
 }

pkg/core/interop/json/json_test.go

@@ -4,7 +4,7 @@ import (
 	"encoding/binary"
 	"testing"
 
-	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
@@ -16,19 +16,13 @@ var (
 	deserializeID = emit.InteropNameToID([]byte("System.Json.Deserialize"))
 )
 
-func getInterop(id uint32) *vm.InteropFuncPrice {
+var jsonInterops = []interop.Function{
-	switch id {
+	{ID: serializeID, Func: Serialize},
-	case serializeID:
+	{ID: deserializeID, Func: Deserialize},
-		return &vm.InteropFuncPrice{
+}
-			Func: func(v *vm.VM) error { return Serialize(nil, v) },
+
-		}
+func init() {
-	case deserializeID:
+	interop.Sort(jsonInterops)
-		return &vm.InteropFuncPrice{
-			Func: func(v *vm.VM) error { return Deserialize(nil, v) },
-		}
-	default:
-		return nil
-	}
 }
 
 func getTestFunc(id uint32, arg interface{}, result interface{}) func(t *testing.T) {
@@ -37,8 +31,9 @@ func getTestFunc(id uint32, arg interface{}, result interface{}) func(t *testing
 	binary.LittleEndian.PutUint32(prog[1:], id)
 
 	return func(t *testing.T) {
-		v := vm.New()
+		ic := &interop.Context{}
-		v.RegisterInteropGetter(getInterop)
+		ic.Functions = append(ic.Functions, jsonInterops)
+		v := ic.SpawnVM()
 		v.LoadScript(prog)
 		v.Estack().PushVal(arg)
 		if result == nil {

pkg/core/interop_system_test.go

@@ -6,6 +6,8 @@ import (
 
 	"github.com/nspcc-dev/dbft/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop/callback"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
@@ -324,7 +326,8 @@ func TestBlockchainGetContractState(t *testing.T) {
 	})
 }
 
-func getTestContractState() *state.Contract {
+// getTestContractState returns 2 contracts second of which is allowed to call the first.
+func getTestContractState() (*state.Contract, *state.Contract) {
 	script := []byte{
 		byte(opcode.ABORT), // abort if no offset was provided
 		byte(opcode.ADD), byte(opcode.RET),
@@ -370,45 +373,51 @@ func getTestContractState() *state.Contract {
 			ReturnType: smartcontract.IntegerType,
 		},
 	}
-	return &state.Contract{
+	cs := &state.Contract{
 		Script:   script,
 		Manifest: *m,
 		ID:       42,
 	}
-}
 
-func TestContractCall(t *testing.T) {
+	currScript := []byte{byte(opcode.RET)}
-	v, ic, bc := createVM(t)
+	m = manifest.NewManifest(hash.Hash160(currScript))
-	defer bc.Close()
-
-	cs := getTestContractState()
-	require.NoError(t, ic.DAO.PutContractState(cs))
-
-	currScript := []byte{byte(opcode.NOP)}
-	initVM := func(v *vm.VM) {
-		v.Istack().Clear()
-		v.Estack().Clear()
-		v.Load(currScript)
-		v.Estack().PushVal(42) // canary
-	}
-
-	h := cs.Manifest.ABI.Hash
-	m := manifest.NewManifest(hash.Hash160(currScript))
 	perm := manifest.NewPermission(manifest.PermissionHash, h)
 	perm.Methods.Add("add")
 	perm.Methods.Add("drop")
 	perm.Methods.Add("add3")
 	m.Permissions = append(m.Permissions, *perm)
 
-	require.NoError(t, ic.DAO.PutContractState(&state.Contract{
+	return cs, &state.Contract{
 		Script:   currScript,
 		Manifest: *m,
 		ID:       123,
-	}))
+	}
+}
+
+func loadScript(script []byte, args ...interface{}) *vm.VM {
+	v := vm.New()
+	v.LoadScriptWithFlags(script, smartcontract.AllowCall)
+	for i := range args {
+		v.Estack().PushVal(args[i])
+	}
+	v.GasLimit = -1
+	return v
+}
+
+func TestContractCall(t *testing.T) {
+	_, ic, bc := createVM(t)
+	defer bc.Close()
+
+	cs, currCs := getTestContractState()
+	require.NoError(t, ic.DAO.PutContractState(cs))
+	require.NoError(t, ic.DAO.PutContractState(currCs))
+
+	currScript := currCs.Script
+	h := cs.Manifest.ABI.Hash
 
 	addArgs := stackitem.NewArray([]stackitem.Item{stackitem.Make(1), stackitem.Make(2)})
 	t.Run("Good", func(t *testing.T) {
-		initVM(v)
+		v := loadScript(currScript, 42)
 		v.Estack().PushVal(addArgs)
 		v.Estack().PushVal("add")
 		v.Estack().PushVal(h.BytesBE())
@@ -420,7 +429,7 @@ func TestContractCall(t *testing.T) {
 	})
 
 	t.Run("CallExInvalidFlag", func(t *testing.T) {
-		initVM(v)
+		v := loadScript(currScript, 42)
 		v.Estack().PushVal(byte(0xFF))
 		v.Estack().PushVal(addArgs)
 		v.Estack().PushVal("add")
@@ -430,7 +439,7 @@ func TestContractCall(t *testing.T) {
 
 	runInvalid := func(args ...interface{}) func(t *testing.T) {
 		return func(t *testing.T) {
-			initVM(v)
+			v := loadScript(currScript, 42)
 			for i := range args {
 				v.Estack().PushVal(args[i])
 			}
@@ -450,7 +459,7 @@ func TestContractCall(t *testing.T) {
 	})
 
 	t.Run("IsolatedStack", func(t *testing.T) {
-		initVM(v)
+		v := loadScript(currScript, 42)
 		v.Estack().PushVal(stackitem.NewArray(nil))
 		v.Estack().PushVal("drop")
 		v.Estack().PushVal(h.BytesBE())
@@ -461,7 +470,7 @@ func TestContractCall(t *testing.T) {
 	t.Run("CallInitialize", func(t *testing.T) {
 		t.Run("Directly", runInvalid(stackitem.NewArray([]stackitem.Item{}), "_initialize", h.BytesBE()))
 
-		initVM(v)
+		v := loadScript(currScript, 42)
 		v.Estack().PushVal(stackitem.NewArray([]stackitem.Item{stackitem.Make(5)}))
 		v.Estack().PushVal("add3")
 		v.Estack().PushVal(h.BytesBE())
@@ -733,3 +742,147 @@ func TestContractGetCallFlags(t *testing.T) {
 	require.NoError(t, contractGetCallFlags(ic, v))
 	require.Equal(t, int64(smartcontract.All), v.Estack().Pop().Value().(*big.Int).Int64())
 }
+
+func TestPointerCallback(t *testing.T) {
+	_, ic, bc := createVM(t)
+	defer bc.Close()
+
+	script := []byte{
+		byte(opcode.NOP), byte(opcode.INC), byte(opcode.RET),
+		byte(opcode.DIV), byte(opcode.RET),
+	}
+	t.Run("Good", func(t *testing.T) {
+		v := loadScript(script, 2, stackitem.NewPointer(3, script))
+		v.Estack().PushVal(v.Context())
+		require.NoError(t, callback.Create(ic, v))
+
+		args := stackitem.NewArray([]stackitem.Item{stackitem.Make(3), stackitem.Make(12)})
+		v.Estack().InsertAt(vm.NewElement(args), 1)
+		require.NoError(t, callback.Invoke(ic, v))
+
+		require.NoError(t, v.Run())
+		require.Equal(t, 1, v.Estack().Len())
+		require.Equal(t, big.NewInt(5), v.Estack().Pop().Item().Value())
+	})
+	t.Run("Invalid", func(t *testing.T) {
+		t.Run("NotEnoughParameters", func(t *testing.T) {
+			v := loadScript(script, 2, stackitem.NewPointer(3, script))
+			v.Estack().PushVal(v.Context())
+			require.NoError(t, callback.Create(ic, v))
+
+			args := stackitem.NewArray([]stackitem.Item{stackitem.Make(3)})
+			v.Estack().InsertAt(vm.NewElement(args), 1)
+			require.Error(t, callback.Invoke(ic, v))
+		})
+	})
+
+}
+
+func TestMethodCallback(t *testing.T) {
+	_, ic, bc := createVM(t)
+	defer bc.Close()
+
+	cs, currCs := getTestContractState()
+	require.NoError(t, ic.DAO.PutContractState(cs))
+	require.NoError(t, ic.DAO.PutContractState(currCs))
+
+	ic.Functions = append(ic.Functions, systemInterops)
+	rawHash := cs.Manifest.ABI.Hash.BytesBE()
+
+	t.Run("Invalid", func(t *testing.T) {
+		runInvalid := func(args ...interface{}) func(t *testing.T) {
+			return func(t *testing.T) {
+				v := loadScript(currCs.Script, 42)
+				for i := range args {
+					v.Estack().PushVal(args[i])
+				}
+				require.Error(t, callback.CreateFromMethod(ic, v))
+			}
+		}
+		t.Run("Hash", runInvalid("add", rawHash[1:]))
+		t.Run("MissingHash", runInvalid("add", util.Uint160{}.BytesBE()))
+		t.Run("MissingMethod", runInvalid("sub", rawHash))
+		t.Run("DisallowedMethod", runInvalid("ret7", rawHash))
+		t.Run("Initialize", runInvalid("_initialize", rawHash))
+		t.Run("NotEnoughArguments", func(t *testing.T) {
+			v := loadScript(currCs.Script, 42, "add", rawHash)
+			require.NoError(t, callback.CreateFromMethod(ic, v))
+
+			v.Estack().InsertAt(vm.NewElement(stackitem.NewArray([]stackitem.Item{stackitem.Make(1)})), 1)
+			require.Error(t, callback.Invoke(ic, v))
+		})
+		t.Run("CallIsNotAllowed", func(t *testing.T) {
+			v := vm.New()
+			v.Load(currCs.Script)
+			v.Estack().PushVal("add")
+			v.Estack().PushVal(rawHash)
+			require.NoError(t, callback.CreateFromMethod(ic, v))
+
+			args := stackitem.NewArray([]stackitem.Item{stackitem.Make(1), stackitem.Make(5)})
+			v.Estack().InsertAt(vm.NewElement(args), 1)
+			require.Error(t, callback.Invoke(ic, v))
+		})
+	})
+
+	t.Run("Good", func(t *testing.T) {
+		v := loadScript(currCs.Script, 42, "add", rawHash)
+		require.NoError(t, callback.CreateFromMethod(ic, v))
+
+		args := stackitem.NewArray([]stackitem.Item{stackitem.Make(1), stackitem.Make(5)})
+		v.Estack().InsertAt(vm.NewElement(args), 1)
+
+		require.NoError(t, callback.Invoke(ic, v))
+		require.NoError(t, v.Run())
+		require.Equal(t, 2, v.Estack().Len())
+		require.Equal(t, big.NewInt(6), v.Estack().Pop().Item().Value())
+		require.Equal(t, big.NewInt(42), v.Estack().Pop().Item().Value())
+	})
+}
+func TestSyscallCallback(t *testing.T) {
+	_, ic, bc := createVM(t)
+	defer bc.Close()
+
+	ic.Functions = append(ic.Functions, []interop.Function{
+		{
+			ID: 0x42,
+			Func: func(_ *interop.Context, v *vm.VM) error {
+				a := v.Estack().Pop().BigInt()
+				b := v.Estack().Pop().BigInt()
+				v.Estack().PushVal(new(big.Int).Add(a, b))
+				return nil
+			},
+			ParamCount: 2,
+		},
+		{
+			ID:               0x53,
+			Func:             func(_ *interop.Context, _ *vm.VM) error { return nil },
+			DisallowCallback: true,
+		},
+	})
+
+	t.Run("Good", func(t *testing.T) {
+		args := stackitem.NewArray([]stackitem.Item{stackitem.Make(12), stackitem.Make(30)})
+		v := loadScript([]byte{byte(opcode.RET)}, args, 0x42)
+		require.NoError(t, callback.CreateFromSyscall(ic, v))
+		require.NoError(t, callback.Invoke(ic, v))
+		require.Equal(t, 1, v.Estack().Len())
+		require.Equal(t, big.NewInt(42), v.Estack().Pop().Item().Value())
+	})
+
+	t.Run("Invalid", func(t *testing.T) {
+		t.Run("InvalidParameterCount", func(t *testing.T) {
+			args := stackitem.NewArray([]stackitem.Item{stackitem.Make(12)})
+			v := loadScript([]byte{byte(opcode.RET)}, args, 0x42)
+			require.NoError(t, callback.CreateFromSyscall(ic, v))
+			require.Error(t, callback.Invoke(ic, v))
+		})
+		t.Run("MissingSyscall", func(t *testing.T) {
+			v := loadScript([]byte{byte(opcode.RET)}, stackitem.NewArray(nil), 0x43)
+			require.Error(t, callback.CreateFromSyscall(ic, v))
+		})
+		t.Run("Disallowed", func(t *testing.T) {
+			v := loadScript([]byte{byte(opcode.RET)}, stackitem.NewArray(nil), 0x53)
+			require.Error(t, callback.CreateFromSyscall(ic, v))
+		})
+	})
+}

pkg/core/interops.go

@@ -8,9 +8,8 @@ package core
 */
 
 import (
-	"sort"
-
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop/callback"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/enumerator"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/iterator"
@@ -25,109 +24,101 @@ import (
 // SpawnVM returns a VM with script getter and interop functions set
 // up for current blockchain.
 func SpawnVM(ic *interop.Context) *vm.VM {
-	vm := vm.NewWithTrigger(ic.Trigger)
+	vm := ic.SpawnVM()
-	vm.RegisterInteropGetter(getSystemInterop(ic))
+	ic.Functions = [][]interop.Function{systemInterops, neoInterops}
-	vm.RegisterInteropGetter(getNeoInterop(ic))
-	ic.ScriptGetter = vm
 	return vm
 }
 
-// getSystemInterop returns matching interop function from the System namespace
-// for a given id in the current context.
-func getSystemInterop(ic *interop.Context) vm.InteropGetterFunc {
-	return getInteropFromSlice(ic, systemInterops)
-}
-
-// getNeoInterop returns matching interop function from the Neo and AntShares
-// namespaces for a given id in the current context.
-func getNeoInterop(ic *interop.Context) vm.InteropGetterFunc {
-	return getInteropFromSlice(ic, neoInterops)
-}
-
-// getInteropFromSlice returns matching interop function from the given slice of
-// interop functions in the current context.
-func getInteropFromSlice(ic *interop.Context, slice []interop.Function) func(uint32) *vm.InteropFuncPrice {
-	return func(id uint32) *vm.InteropFuncPrice {
-		n := sort.Search(len(slice), func(i int) bool {
-			return slice[i].ID >= id
-		})
-		if n < len(slice) && slice[n].ID == id {
-			return &vm.InteropFuncPrice{
-				Func: func(v *vm.VM) error {
-					return slice[n].Func(ic, v)
-				},
-				Price:         slice[n].Price,
-				RequiredFlags: slice[n].RequiredFlags,
-			}
-		}
-		return nil
-	}
-}
-
 // All lists are sorted, keep 'em this way, please.
 var systemInterops = []interop.Function{
-	{Name: "System.Binary.Base64Decode", Func: runtimeDecode, Price: 100000},
+	{Name: "System.Binary.Base64Decode", Func: runtimeDecode, Price: 100000, ParamCount: 1},
-	{Name: "System.Binary.Base64Encode", Func: runtimeEncode, Price: 100000},
+	{Name: "System.Binary.Base64Encode", Func: runtimeEncode, Price: 100000, ParamCount: 1},
-	{Name: "System.Binary.Deserialize", Func: runtimeDeserialize, Price: 500000},
+	{Name: "System.Binary.Deserialize", Func: runtimeDeserialize, Price: 500000, ParamCount: 1},
-	{Name: "System.Binary.Serialize", Func: runtimeSerialize, Price: 100000},
+	{Name: "System.Binary.Serialize", Func: runtimeSerialize, Price: 100000, ParamCount: 1},
-	{Name: "System.Blockchain.GetBlock", Func: bcGetBlock, Price: 2500000, RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Blockchain.GetBlock", Func: bcGetBlock, Price: 2500000,
-	{Name: "System.Blockchain.GetContract", Func: bcGetContract, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1},
-	{Name: "System.Blockchain.GetHeight", Func: bcGetHeight, Price: 400, RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Blockchain.GetContract", Func: bcGetContract, Price: 1000000,
-	{Name: "System.Blockchain.GetTransaction", Func: bcGetTransaction, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1},
-	{Name: "System.Blockchain.GetTransactionFromBlock", Func: bcGetTransactionFromBlock, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Blockchain.GetHeight", Func: bcGetHeight, Price: 400,
-	{Name: "System.Blockchain.GetTransactionHeight", Func: bcGetTransactionHeight, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
-	{Name: "System.Contract.Call", Func: contractCall, Price: 1000000, RequiredFlags: smartcontract.AllowCall},
-	{Name: "System.Contract.CallEx", Func: contractCallEx, Price: 1000000, RequiredFlags: smartcontract.AllowCall},
-	{Name: "System.Contract.Create", Func: contractCreate, Price: 0, RequiredFlags: smartcontract.AllowModifyStates},
-	{Name: "System.Contract.CreateStandardAccount", Func: contractCreateStandardAccount, Price: 10000},
-	{Name: "System.Contract.Destroy", Func: contractDestroy, Price: 1000000, RequiredFlags: smartcontract.AllowModifyStates},
-	{Name: "System.Contract.IsStandard", Func: contractIsStandard, Price: 30000},
-	{Name: "System.Contract.GetCallFlags", Func: contractGetCallFlags, Price: 30000},
-	{Name: "System.Contract.Update", Func: contractUpdate, Price: 0, RequiredFlags: smartcontract.AllowModifyStates},
-	{Name: "System.Enumerator.Concat", Func: enumerator.Concat, Price: 400},
-	{Name: "System.Enumerator.Create", Func: enumerator.Create, Price: 400},
-	{Name: "System.Enumerator.Next", Func: enumerator.Next, Price: 1000000},
-	{Name: "System.Enumerator.Value", Func: enumerator.Value, Price: 400},
-	{Name: "System.Iterator.Concat", Func: iterator.Concat, Price: 400},
-	{Name: "System.Iterator.Create", Func: iterator.Create, Price: 400},
-	{Name: "System.Iterator.Key", Func: iterator.Key, Price: 400},
-	{Name: "System.Iterator.Keys", Func: iterator.Keys, Price: 400},
-	{Name: "System.Iterator.Values", Func: iterator.Values, Price: 400},
-	{Name: "System.Json.Deserialize", Func: json.Deserialize, Price: 500000},
-	{Name: "System.Json.Serialize", Func: json.Serialize, Price: 100000},
-	{Name: "System.Runtime.CheckWitness", Func: runtime.CheckWitness, Price: 30000,
 		RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Blockchain.GetTransaction", Func: bcGetTransaction, Price: 1000000,
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1},
+	{Name: "System.Blockchain.GetTransactionFromBlock", Func: bcGetTransactionFromBlock, Price: 1000000,
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 2},
+	{Name: "System.Blockchain.GetTransactionHeight", Func: bcGetTransactionHeight, Price: 1000000,
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1},
+	{Name: "System.Callback.Create", Func: callback.Create, Price: 400, ParamCount: 3, DisallowCallback: true},
+	{Name: "System.Callback.CreateFromMethod", Func: callback.CreateFromMethod, Price: 1000000, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Callback.CreateFromSyscall", Func: callback.CreateFromSyscall, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Callback.Invoke", Func: callback.Invoke, Price: 1000000, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Contract.Call", Func: contractCall, Price: 1000000,
+		RequiredFlags: smartcontract.AllowCall, ParamCount: 3, DisallowCallback: true},
+	{Name: "System.Contract.CallEx", Func: contractCallEx, Price: 1000000,
+		RequiredFlags: smartcontract.AllowCall, ParamCount: 4, DisallowCallback: true},
+	{Name: "System.Contract.Create", Func: contractCreate, Price: 0,
+		RequiredFlags: smartcontract.AllowModifyStates, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Contract.CreateStandardAccount", Func: contractCreateStandardAccount, Price: 10000, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Contract.Destroy", Func: contractDestroy, Price: 1000000, RequiredFlags: smartcontract.AllowModifyStates, DisallowCallback: true},
+	{Name: "System.Contract.IsStandard", Func: contractIsStandard, Price: 30000, ParamCount: 1},
+	{Name: "System.Contract.GetCallFlags", Func: contractGetCallFlags, Price: 30000, DisallowCallback: true},
+	{Name: "System.Contract.Update", Func: contractUpdate, Price: 0,
+		RequiredFlags: smartcontract.AllowModifyStates, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Enumerator.Concat", Func: enumerator.Concat, Price: 400, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Enumerator.Create", Func: enumerator.Create, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Enumerator.Next", Func: enumerator.Next, Price: 1000000, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Enumerator.Value", Func: enumerator.Value, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Iterator.Concat", Func: iterator.Concat, Price: 400, ParamCount: 2, DisallowCallback: true},
+	{Name: "System.Iterator.Create", Func: iterator.Create, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Iterator.Key", Func: iterator.Key, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Iterator.Keys", Func: iterator.Keys, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Iterator.Values", Func: iterator.Values, Price: 400, ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Json.Deserialize", Func: json.Deserialize, Price: 500000, ParamCount: 1},
+	{Name: "System.Json.Serialize", Func: json.Serialize, Price: 100000, ParamCount: 1},
+	{Name: "System.Runtime.CheckWitness", Func: runtime.CheckWitness, Price: 30000,
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1},
 	{Name: "System.Runtime.GasLeft", Func: runtime.GasLeft, Price: 400},
 	{Name: "System.Runtime.GetCallingScriptHash", Func: engineGetCallingScriptHash, Price: 400},
 	{Name: "System.Runtime.GetEntryScriptHash", Func: engineGetEntryScriptHash, Price: 400},
 	{Name: "System.Runtime.GetExecutingScriptHash", Func: engineGetExecutingScriptHash, Price: 400},
 	{Name: "System.Runtime.GetInvocationCounter", Func: runtime.GetInvocationCounter, Price: 400},
-	{Name: "System.Runtime.GetNotifications", Func: runtime.GetNotifications, Price: 10000},
+	{Name: "System.Runtime.GetNotifications", Func: runtime.GetNotifications, Price: 10000, ParamCount: 1},
 	{Name: "System.Runtime.GetScriptContainer", Func: engineGetScriptContainer, Price: 250},
 	{Name: "System.Runtime.GetTime", Func: runtimeGetTime, Price: 250, RequiredFlags: smartcontract.AllowStates},
 	{Name: "System.Runtime.GetTrigger", Func: runtimeGetTrigger, Price: 250},
-	{Name: "System.Runtime.Log", Func: runtimeLog, Price: 1000000, RequiredFlags: smartcontract.AllowNotify},
+	{Name: "System.Runtime.Log", Func: runtimeLog, Price: 1000000, RequiredFlags: smartcontract.AllowNotify,
-	{Name: "System.Runtime.Notify", Func: runtimeNotify, Price: 1000000, RequiredFlags: smartcontract.AllowNotify},
+		ParamCount: 1, DisallowCallback: true},
+	{Name: "System.Runtime.Notify", Func: runtimeNotify, Price: 1000000, RequiredFlags: smartcontract.AllowNotify,
+		ParamCount: 2, DisallowCallback: true},
 	{Name: "System.Runtime.Platform", Func: runtimePlatform, Price: 250},
-	{Name: "System.Storage.Delete", Func: storageDelete, Price: StoragePrice, RequiredFlags: smartcontract.AllowModifyStates},
+	{Name: "System.Storage.Delete", Func: storageDelete, Price: StoragePrice,
-	{Name: "System.Storage.Find", Func: storageFind, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
+		RequiredFlags: smartcontract.AllowModifyStates, ParamCount: 2, DisallowCallback: true},
-	{Name: "System.Storage.Get", Func: storageGet, Price: 1000000, RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Storage.Find", Func: storageFind, Price: 1000000, RequiredFlags: smartcontract.AllowStates,
-	{Name: "System.Storage.GetContext", Func: storageGetContext, Price: 400, RequiredFlags: smartcontract.AllowStates},
+		ParamCount: 2, DisallowCallback: true},
-	{Name: "System.Storage.GetReadOnlyContext", Func: storageGetReadOnlyContext, Price: 400, RequiredFlags: smartcontract.AllowStates},
+	{Name: "System.Storage.Get", Func: storageGet, Price: 1000000, RequiredFlags: smartcontract.AllowStates,
-	{Name: "System.Storage.Put", Func: storagePut, Price: 0, RequiredFlags: smartcontract.AllowModifyStates}, // These don't have static price in C# code.
+		ParamCount: 2, DisallowCallback: true},
-	{Name: "System.Storage.PutEx", Func: storagePutEx, Price: 0, RequiredFlags: smartcontract.AllowModifyStates},
+	{Name: "System.Storage.GetContext", Func: storageGetContext, Price: 400,
-	{Name: "System.Storage.AsReadOnly", Func: storageContextAsReadOnly, Price: 400, RequiredFlags: smartcontract.AllowStates},
+		RequiredFlags: smartcontract.AllowStates, DisallowCallback: true},
+	{Name: "System.Storage.GetReadOnlyContext", Func: storageGetReadOnlyContext, Price: 400,
+		RequiredFlags: smartcontract.AllowStates, DisallowCallback: true},
+	{Name: "System.Storage.Put", Func: storagePut, Price: 0, RequiredFlags: smartcontract.AllowModifyStates,
+		ParamCount: 3, DisallowCallback: true}, // These don't have static price in C# code.
+	{Name: "System.Storage.PutEx", Func: storagePutEx, Price: 0, RequiredFlags: smartcontract.AllowModifyStates,
+		ParamCount: 4, DisallowCallback: true},
+	{Name: "System.Storage.AsReadOnly", Func: storageContextAsReadOnly, Price: 400,
+		RequiredFlags: smartcontract.AllowStates, ParamCount: 1, DisallowCallback: true},
 }
 
 var neoInterops = []interop.Function{
-	{Name: "Neo.Crypto.VerifyWithECDsaSecp256r1", Func: crypto.ECDSASecp256r1Verify, Price: crypto.ECDSAVerifyPrice},
+	{Name: "Neo.Crypto.VerifyWithECDsaSecp256r1", Func: crypto.ECDSASecp256r1Verify,
-	{Name: "Neo.Crypto.VerifyWithECDsaSecp256k1", Func: crypto.ECDSASecp256k1Verify, Price: crypto.ECDSAVerifyPrice},
+		Price: crypto.ECDSAVerifyPrice, ParamCount: 3},
-	{Name: "Neo.Crypto.CheckMultisigWithECDsaSecp256r1", Func: crypto.ECDSASecp256r1CheckMultisig, Price: 0},
+	{Name: "Neo.Crypto.VerifyWithECDsaSecp256k1", Func: crypto.ECDSASecp256k1Verify,
-	{Name: "Neo.Crypto.CheckMultisigWithECDsaSecp256k1", Func: crypto.ECDSASecp256k1CheckMultisig, Price: 0},
+		Price: crypto.ECDSAVerifyPrice, ParamCount: 3},
-	{Name: "Neo.Crypto.SHA256", Func: crypto.Sha256, Price: 1000000},
+	{Name: "Neo.Crypto.CheckMultisigWithECDsaSecp256r1", Func: crypto.ECDSASecp256r1CheckMultisig, Price: 0, ParamCount: 3},
-	{Name: "Neo.Crypto.RIPEMD160", Func: crypto.RipeMD160, Price: 1000000},
+	{Name: "Neo.Crypto.CheckMultisigWithECDsaSecp256k1", Func: crypto.ECDSASecp256k1CheckMultisig, Price: 0, ParamCount: 3},
-	{Name: "Neo.Native.Call", Func: native.Call, Price: 0},
+	{Name: "Neo.Crypto.SHA256", Func: crypto.Sha256, Price: 1000000, ParamCount: 1},
-	{Name: "Neo.Native.Deploy", Func: native.Deploy, Price: 0, RequiredFlags: smartcontract.AllowModifyStates},
+	{Name: "Neo.Crypto.RIPEMD160", Func: crypto.RipeMD160, Price: 1000000, ParamCount: 1},
+	{Name: "Neo.Native.Call", Func: native.Call, Price: 0, ParamCount: 1, DisallowCallback: true},
+	{Name: "Neo.Native.Deploy", Func: native.Deploy, Price: 0, RequiredFlags: smartcontract.AllowModifyStates, DisallowCallback: true},
 }
 
 // initIDinInteropsSlice initializes IDs from names in one given
@@ -136,9 +127,7 @@ func initIDinInteropsSlice(iops []interop.Function) {
 	for i := range iops {
 		iops[i].ID = emit.InteropNameToID([]byte(iops[i].Name))
 	}
-	sort.Slice(iops, func(i, j int) bool {
+	interop.Sort(iops)
-		return iops[i].ID < iops[j].ID
-	})
 }
 
 // init initializes IDs in the global interop slices.

pkg/core/opcode_price.go

@@ -68,11 +68,11 @@ var prices = map[opcode.Opcode]int64{
 	opcode.ABORT:        30,
 	opcode.ASSERT:       30,
 	opcode.THROW:        22000,
-	//opcode.TRY: 100,
+	opcode.TRY:          100,
-	//opcode.TRY_L: 100,
+	opcode.TRYL:         100,
-	//opcode.ENDTRY: 100,
+	opcode.ENDTRY:       100,
-	//opcode.ENDTRY_L: 100,
+	opcode.ENDTRYL:      100,
-	//opcode.ENDFINALLY: 100,
+	opcode.ENDFINALLY:   100,
 	opcode.RET:          0,
 	opcode.SYSCALL:      0,
 	opcode.DEPTH:        60,

pkg/smartcontract/context/context_test.go

@@ -110,9 +110,9 @@ func TestParameterContext_AddSignatureMultisig(t *testing.T) {
 }
 
 func newTestVM(w *transaction.Witness, tx *transaction.Transaction) *vm.VM {
-	v := vm.New()
+	ic := &interop.Context{Container: tx}
-	v.GasLimit = -1
+	crypto.Register(ic)
-	v.RegisterInteropGetter(crypto.GetInterop(&interop.Context{Container: tx}))
+	v := ic.SpawnVM()
 	v.LoadScript(w.VerificationScript)
 	v.LoadScript(w.InvocationScript)
 	return v

pkg/vm/interop.go

@@ -10,63 +10,59 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
 
-// InteropFunc allows to hook into the VM.
+// interopIDFuncPrice adds an ID to the InteropFuncPrice.
-type InteropFunc func(vm *VM) error
+type interopIDFuncPrice struct {
-
+	ID            uint32
-// InteropFuncPrice represents an interop function with a price.
+	Func          func(vm *VM) error
-type InteropFuncPrice struct {
-	Func          InteropFunc
 	Price         int64
 	RequiredFlags smartcontract.CallFlag
 }
 
-// interopIDFuncPrice adds an ID to the InteropFuncPrice.
-type interopIDFuncPrice struct {
-	ID uint32
-	InteropFuncPrice
-}
-
-// InteropGetterFunc is a function that returns an interop function-price
-// structure by the given interop ID.
-type InteropGetterFunc func(uint32) *InteropFuncPrice
-
 var defaultVMInterops = []interopIDFuncPrice{
-	{emit.InteropNameToID([]byte("System.Binary.Deserialize")),
+	{ID: emit.InteropNameToID([]byte("System.Binary.Deserialize")),
-		InteropFuncPrice{Func: RuntimeDeserialize, Price: 500000}},
+		Func: RuntimeDeserialize, Price: 500000},
-	{emit.InteropNameToID([]byte("System.Binary.Serialize")),
+	{ID: emit.InteropNameToID([]byte("System.Binary.Serialize")),
-		InteropFuncPrice{Func: RuntimeSerialize, Price: 100000}},
+		Func: RuntimeSerialize, Price: 100000},
-	{emit.InteropNameToID([]byte("System.Runtime.Log")),
+	{ID: emit.InteropNameToID([]byte("System.Runtime.Log")),
-		InteropFuncPrice{Func: runtimeLog, Price: 1000000, RequiredFlags: smartcontract.AllowNotify}},
+		Func: runtimeLog, Price: 1000000, RequiredFlags: smartcontract.AllowNotify},
-	{emit.InteropNameToID([]byte("System.Runtime.Notify")),
+	{ID: emit.InteropNameToID([]byte("System.Runtime.Notify")),
-		InteropFuncPrice{Func: runtimeNotify, Price: 1000000, RequiredFlags: smartcontract.AllowNotify}},
+		Func: runtimeNotify, Price: 1000000, RequiredFlags: smartcontract.AllowNotify},
-	{emit.InteropNameToID([]byte("System.Enumerator.Create")),
+	{ID: emit.InteropNameToID([]byte("System.Enumerator.Create")),
-		InteropFuncPrice{Func: EnumeratorCreate, Price: 400}},
+		Func: EnumeratorCreate, Price: 400},
-	{emit.InteropNameToID([]byte("System.Enumerator.Next")),
+	{ID: emit.InteropNameToID([]byte("System.Enumerator.Next")),
-		InteropFuncPrice{Func: EnumeratorNext, Price: 1000000}},
+		Func: EnumeratorNext, Price: 1000000},
-	{emit.InteropNameToID([]byte("System.Enumerator.Concat")),
+	{ID: emit.InteropNameToID([]byte("System.Enumerator.Concat")),
-		InteropFuncPrice{Func: EnumeratorConcat, Price: 400}},
+		Func: EnumeratorConcat, Price: 400},
-	{emit.InteropNameToID([]byte("System.Enumerator.Value")),
+	{ID: emit.InteropNameToID([]byte("System.Enumerator.Value")),
-		InteropFuncPrice{Func: EnumeratorValue, Price: 400}},
+		Func: EnumeratorValue, Price: 400},
-	{emit.InteropNameToID([]byte("System.Iterator.Create")),
+	{ID: emit.InteropNameToID([]byte("System.Iterator.Create")),
-		InteropFuncPrice{Func: IteratorCreate, Price: 400}},
+		Func: IteratorCreate, Price: 400},
-	{emit.InteropNameToID([]byte("System.Iterator.Concat")),
+	{ID: emit.InteropNameToID([]byte("System.Iterator.Concat")),
-		InteropFuncPrice{Func: IteratorConcat, Price: 400}},
+		Func: IteratorConcat, Price: 400},
-	{emit.InteropNameToID([]byte("System.Iterator.Key")),
+	{ID: emit.InteropNameToID([]byte("System.Iterator.Key")),
-		InteropFuncPrice{Func: IteratorKey, Price: 400}},
+		Func: IteratorKey, Price: 400},
-	{emit.InteropNameToID([]byte("System.Iterator.Keys")),
+	{ID: emit.InteropNameToID([]byte("System.Iterator.Keys")),
-		InteropFuncPrice{Func: IteratorKeys, Price: 400}},
+		Func: IteratorKeys, Price: 400},
-	{emit.InteropNameToID([]byte("System.Iterator.Values")),
+	{ID: emit.InteropNameToID([]byte("System.Iterator.Values")),
-		InteropFuncPrice{Func: IteratorValues, Price: 400}},
+		Func: IteratorValues, Price: 400},
 }
 
-func getDefaultVMInterop(id uint32) *InteropFuncPrice {
+func init() {
+	sort.Slice(defaultVMInterops, func(i, j int) bool { return defaultVMInterops[i].ID < defaultVMInterops[j].ID })
+}
+
+func defaultSyscallHandler(v *VM, id uint32) error {
 	n := sort.Search(len(defaultVMInterops), func(i int) bool {
 		return defaultVMInterops[i].ID >= id
 	})
-	if n < len(defaultVMInterops) && defaultVMInterops[n].ID == id {
+	if n >= len(defaultVMInterops) || defaultVMInterops[n].ID != id {
-		return &defaultVMInterops[n].InteropFuncPrice
+		return errors.New("syscall not found")
 	}
-	return nil
+	d := defaultVMInterops[n]
+	if !v.Context().callFlag.Has(d.RequiredFlags) {
+		return fmt.Errorf("missing call flags: %05b vs %05b", v.Context().callFlag, d.RequiredFlags)
+	}
+	return d.Func(v)
 }
 
 // runtimeLog handles the syscall "System.Runtime.Log" for printing and logging stuff.

pkg/vm/json_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/pkg/errors"
 	"github.com/stretchr/testify/require"
 )
 
@@ -110,30 +111,21 @@ func TestUT(t *testing.T) {
 	require.Equal(t, true, testsRan, "neo-vm tests should be available (check submodules)")
 }
 
-func getTestingInterop(id uint32) *InteropFuncPrice {
+func testSyscallHandler(v *VM, id uint32) error {
-	f := func(v *VM) error {
-		v.estack.PushVal(stackitem.NewInterop(new(int)))
-		return nil
-	}
 	switch id {
 	case 0x77777777:
-		return &InteropFuncPrice{Func: f}
+		v.Estack().PushVal(stackitem.NewInterop(new(int)))
 	case 0x66666666:
-		return &InteropFuncPrice{
+		if !v.Context().callFlag.Has(smartcontract.ReadOnly) {
-			Func:          f,
+			return errors.New("invalid call flags")
-			RequiredFlags: smartcontract.ReadOnly,
 		}
+		v.Estack().PushVal(stackitem.NewInterop(new(int)))
 	case 0x55555555:
-		return &InteropFuncPrice{
+		v.Estack().PushVal(stackitem.NewInterop(new(int)))
-			Func: f,
-		}
 	case 0xADDEADDE:
-		return &InteropFuncPrice{
-			Func: func(v *VM) error {
 		v.throw(stackitem.Make("error"))
-				return nil
+	default:
-			},
+		return errors.New("syscall not found")
-		}
 	}
 	return nil
 }
@@ -163,7 +155,7 @@ func testFile(t *testing.T, filename string) {
 				prog := []byte(test.Script)
 				vm := load(prog)
 				vm.state = BreakState
-				vm.RegisterInteropGetter(getTestingInterop)
+				vm.SyscallHandler = testSyscallHandler
 
 				for i := range test.Steps {
 					execStep(t, vm, test.Steps[i])

pkg/vm/vm.go

@@ -58,13 +58,13 @@ const (
 	maxSHLArg = stackitem.MaxBigIntegerSizeBits
 )
 
+// SyscallHandler is a type for syscall handler.
+type SyscallHandler = func(*VM, uint32) error
+
 // VM represents the virtual machine.
 type VM struct {
 	state State
 
-	// callbacks to get interops.
-	getInterop []InteropGetterFunc
-
 	// callback to get interop price
 	getPrice func(*VM, opcode.Opcode, []byte) int64
 
@@ -78,6 +78,9 @@ type VM struct {
 	gasConsumed int64
 	GasLimit    int64
 
+	// SyscallHandler handles SYSCALL opcode.
+	SyscallHandler func(v *VM, id uint32) error
+
 	trigger trigger.Type
 
 	// Public keys cache.
@@ -92,17 +95,16 @@ func New() *VM {
 // NewWithTrigger returns a new VM for executions triggered by t.
 func NewWithTrigger(t trigger.Type) *VM {
 	vm := &VM{
-		getInterop: make([]InteropGetterFunc, 0, 3), // 3 functions is typical for our default usage.
 		state:   HaltState,
 		istack:  NewStack("invocation"),
 		refs:    newRefCounter(),
 		keys:    make(map[string]*keys.PublicKey),
 		trigger: t,
+
+		SyscallHandler: defaultSyscallHandler,
 	}
 
 	vm.estack = vm.newItemStack("evaluation")
-
-	vm.RegisterInteropGetter(getDefaultVMInterop)
 	return vm
 }
 
@@ -113,13 +115,6 @@ func (v *VM) newItemStack(n string) *Stack {
 	return s
 }
 
-// RegisterInteropGetter registers the given InteropGetterFunc into VM. There
-// can be many interop getters and they're probed in LIFO order wrt their
-// registration time.
-func (v *VM) RegisterInteropGetter(f InteropGetterFunc) {
-	v.getInterop = append(v.getInterop, f)
-}
-
 // SetPriceGetter registers the given PriceGetterFunc in v.
 // f accepts vm's Context, current instruction and instruction parameter.
 func (v *VM) SetPriceGetter(f func(*VM, opcode.Opcode, []byte) int64) {
@@ -494,18 +489,6 @@ func GetInteropID(parameter []byte) uint32 {
 	return binary.LittleEndian.Uint32(parameter)
 }
 
-// GetInteropByID returns interop function together with price.
-// Registered callbacks are checked in LIFO order.
-func (v *VM) GetInteropByID(id uint32) *InteropFuncPrice {
-	for i := len(v.getInterop) - 1; i >= 0; i-- {
-		if ifunc := v.getInterop[i](id); ifunc != nil {
-			return ifunc
-		}
-	}
-
-	return nil
-}
-
 // execute performs an instruction cycle in the VM. Acting on the instruction (opcode).
 func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err error) {
 	// Instead of polluting the whole VM logic with error handling, we will recover
@@ -1250,15 +1233,8 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 
 	case opcode.SYSCALL:
 		interopID := GetInteropID(parameter)
-		ifunc := v.GetInteropByID(interopID)
+		err := v.SyscallHandler(v, interopID)
-		if !v.Context().callFlag.Has(ifunc.RequiredFlags) {
+		if err != nil {
-			panic(fmt.Sprintf("missing call flags: %05b vs %05b", v.Context().callFlag, ifunc.RequiredFlags))
-		}
-
-		if ifunc == nil {
-			panic(fmt.Sprintf("interop hook (%q/0x%x) not registered", parameter, interopID))
-		}
-		if err := ifunc.Func(v); err != nil {
 			panic(fmt.Sprintf("failed to invoke syscall: %s", err))
 		}
 

pkg/vm/vm_test.go

@@ -17,26 +17,25 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func fooInteropGetter(id uint32) *InteropFuncPrice {
+func fooInteropHandler(v *VM, id uint32) error {
 	if id == emit.InteropNameToID([]byte("foo")) {
-		return &InteropFuncPrice{
+		if !v.AddGas(1) {
-			Func: func(evm *VM) error {
+			return errors.New("invalid gas amount")
-				evm.Estack().PushVal(1)
-				return nil
-			},
-			Price: 1,
-		}
 		}
+		v.Estack().PushVal(1)
 		return nil
+	}
+	return errors.New("syscall not found")
 }
 
 func TestInteropHook(t *testing.T) {
 	v := newTestVM()
-	v.RegisterInteropGetter(fooInteropGetter)
+	v.SyscallHandler = fooInteropHandler
 
 	buf := io.NewBufBinWriter()
 	emit.Syscall(buf.BinWriter, "foo")
@@ -47,13 +46,6 @@ func TestInteropHook(t *testing.T) {
 	assert.Equal(t, big.NewInt(1), v.estack.Pop().value.Value())
 }
 
-func TestRegisterInteropGetter(t *testing.T) {
-	v := newTestVM()
-	currRegistered := len(v.getInterop)
-	v.RegisterInteropGetter(fooInteropGetter)
-	assert.Equal(t, currRegistered+1, len(v.getInterop))
-}
-
 func TestVM_SetPriceGetter(t *testing.T) {
 	v := newTestVM()
 	prog := []byte{
@@ -819,7 +811,7 @@ func getTestCallFlagsFunc(syscall []byte, flags smartcontract.CallFlag, result i
 	return func(t *testing.T) {
 		script := append([]byte{byte(opcode.SYSCALL)}, syscall...)
 		v := newTestVM()
-		v.RegisterInteropGetter(getTestingInterop)
+		v.SyscallHandler = testSyscallHandler
 		v.LoadScriptWithFlags(script, flags)
 		if result == nil {
 			checkVMFailed(t, v)