rpc/core: implement invokescript method, fix #348

Extend Blockchainer with one more method to spawn a VM for test runs and use
it to run scripts. Gas consumption is not counted or limited in any way at the
moment (see #424).

pkg/core/blockchain.go

@@ -1111,6 +1111,14 @@ func (bc *Blockchain) spawnVMWithInterops(interopCtx *interopContext) *vm.VM {
 	return vm
 }
 
+// GetTestVM returns a VM and a Store setup for a test run of some sort of code.
+func (bc *Blockchain) GetTestVM() (*vm.VM, storage.Store) {
+	tmpStore := storage.NewMemCachedStore(bc.store)
+	systemInterop := newInteropContext(0x10, bc, tmpStore, nil, nil)
+	vm := bc.spawnVMWithInterops(systemInterop)
+	return vm, tmpStore
+}
+
 // verifyHashAgainstScript verifies given hash against the given witness.
 func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transaction.Witness, checkedHash util.Uint256, interopCtx *interopContext) error {
 	verification := witness.VerificationScript

pkg/core/blockchainer.go

@@ -2,8 +2,10 @@ package core
 
 import (
 	"github.com/CityOfZion/neo-go/config"
+	"github.com/CityOfZion/neo-go/pkg/core/storage"
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm"
 )
 
 // Blockchainer is an interface that abstract the implementation
@@ -27,6 +29,7 @@ type Blockchainer interface {
 	GetScriptHashesForVerifying(*transaction.Transaction) ([]util.Uint160, error)
 	GetStorageItem(scripthash util.Uint160, key []byte) *StorageItem
 	GetStorageItems(hash util.Uint160) (map[string]*StorageItem, error)
+	GetTestVM() (*vm.VM, storage.Store)
 	GetTransaction(util.Uint256) (*transaction.Transaction, uint32, error)
 	GetUnspentCoinState(util.Uint256) *UnspentCoinState
 	References(t *transaction.Transaction) map[transaction.Input]*transaction.Output

pkg/network/helper_test.go

@@ -9,9 +9,11 @@ import (
 
 	"github.com/CityOfZion/neo-go/config"
 	"github.com/CityOfZion/neo-go/pkg/core"
+	"github.com/CityOfZion/neo-go/pkg/core/storage"
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/network/payload"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm"
 )
 
 type testChain struct {
@@ -78,6 +80,9 @@ func (chain testChain) GetScriptHashesForVerifying(*transaction.Transaction) ([]
 func (chain testChain) GetStorageItem(scripthash util.Uint160, key []byte) *core.StorageItem {
 	panic("TODO")
 }
+func (chain testChain) GetTestVM() (*vm.VM, storage.Store) {
+	panic("TODO")
+}
 func (chain testChain) GetStorageItems(hash util.Uint160) (map[string]*core.StorageItem, error) {
 	panic("TODO")
 }

pkg/rpc/server.go

@@ -227,6 +227,9 @@ Methods:
 	case "getrawtransaction":
 		results, resultsErr = s.getrawtransaction(reqParams)
 
+	case "invokescript":
+		results, resultsErr = s.invokescript(reqParams)
+
 	case "sendrawtransaction":
 		results, resultsErr = s.sendrawtransaction(reqParams)
 
@@ -280,6 +283,28 @@ func (s *Server) getrawtransaction(reqParams Params) (interface{}, error) {
 	return results, resultsErr
 }
 
+// invokescript implements the `invokescript` RPC call.
+func (s *Server) invokescript(reqParams Params) (interface{}, error) {
+	hexScript, err := reqParams.ValueWithType(0, "string")
+	if err != nil {
+		return nil, err
+	}
+	script, err := hex.DecodeString(hexScript.StringVal)
+	if err != nil {
+		return nil, err
+	}
+	vm, _ := s.chain.GetTestVM()
+	vm.LoadScript(script)
+	_ = vm.Run()
+	result := &wrappers.InvokeResult{
+		State:       vm.State(),
+		GasConsumed: "0.1",
+		Script:      hexScript.StringVal,
+		Stack:       vm.Estack(),
+	}
+	return result, nil
+}
+
 func (s *Server) sendrawtransaction(reqParams Params) (interface{}, error) {
 	var resultsErr error
 	var results interface{}

pkg/rpc/wrappers/invoke_result.go

@@ -0,0 +1,13 @@
+package wrappers
+
+import (
+	"github.com/CityOfZion/neo-go/pkg/vm"
+)
+
+// InvokeResult is used as a wrapper to represent an invokation result.
+type InvokeResult struct {
+	State       string `json:"state"`
+	GasConsumed string `json:"gas_consumed"`
+	Script      string `json:"script"`
+	Stack       *vm.Stack
+}