Merge pull request #511 from nspcc-dev/contract-deployment

Contract deployment

cli/smartcontract/smart_contract.go

@@ -11,9 +11,13 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
+	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/rpc"
+	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/CityOfZion/neo-go/pkg/vm"
 	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
+	"github.com/go-yaml/yaml"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 )
@@ -21,6 +25,8 @@ import (
 var (
 	errNoEndpoint          = errors.New("no RPC endpoint specified, use option '--endpoint' or '-e'")
 	errNoInput             = errors.New("no input file was found, specify an input file with the '--in or -i' flag")
+	errNoConfFile          = errors.New("no config file was found, specify a config file with the '--config' or '-c' flag")
+	errNoWIF               = errors.New("no WIF parameter found, specify it with the '--wif or -w' flag")
 	errNoSmartContractName = errors.New("no name was provided, specify the '--name or -n' flag")
 	errFileExist           = errors.New("A file with given smart-contract name already exists")
 )
@@ -62,6 +68,33 @@ func NewCommands() []cli.Command {
 					},
 				},
 			},
+			{
+				Name:   "deploy",
+				Usage:  "deploy a smart contract (.avm with description)",
+				Action: contractDeploy,
+				Flags: []cli.Flag{
+					cli.StringFlag{
+						Name:  "in, i",
+						Usage: "Input file for the smart contract (*.avm)",
+					},
+					cli.StringFlag{
+						Name:  "config, c",
+						Usage: "configuration input file (*.yml)",
+					},
+					cli.StringFlag{
+						Name:  "endpoint, e",
+						Usage: "RPC endpoint address (like 'http://seed4.ngd.network:20332')",
+					},
+					cli.StringFlag{
+						Name:  "wif, w",
+						Usage: "key to sign deployed transaction (in wif format)",
+					},
+					cli.IntFlag{
+						Name:  "gas, g",
+						Usage: "gas to pay for contract deployment",
+					},
+				},
+			},
 			{
 				Name:   "testinvoke",
 				Usage:  "Test an invocation of a smart contract on the blockchain",
@@ -135,7 +168,17 @@ func initSmartContract(ctx *cli.Context) error {
 	// TODO: Fix the missing neo-go.yml file with the `init` command when the package manager is in place.
 	if !ctx.Bool("skip-details") {
 		details := parseContractDetails()
-		if err := ioutil.WriteFile(filepath.Join(basePath, "neo-go.yml"), details.toStormFile(), 0644); err != nil {
+		details.ReturnType = rpc.ByteArray
+		details.Parameters = make([]rpc.StackParamType, 2)
+		details.Parameters[0] = rpc.String
+		details.Parameters[1] = rpc.Array
+
+		project := &ProjectConfig{Contract: details}
+		b, err := yaml.Marshal(project)
+		if err != nil {
+			return cli.NewExitError(err, 1)
+		}
+		if err := ioutil.WriteFile(filepath.Join(basePath, "neo-go.yml"), b, 0644); err != nil {
 			return cli.NewExitError(err, 1)
 		}
 	}
@@ -204,42 +247,14 @@ func testInvoke(ctx *cli.Context) error {
 	return nil
 }
 
-// ContractDetails contains contract metadata.
+// ProjectConfig contains project metadata.
-type ContractDetails struct {
+type ProjectConfig struct {
-	Author      string
+	Version  uint
-	Email       string
+	Contract rpc.ContractDetails `yaml:"project"`
-	Version     string
-	ProjectName string
-	Description string
 }
 
-func (d ContractDetails) toStormFile() []byte {
+func parseContractDetails() rpc.ContractDetails {
-	buf := new(bytes.Buffer)
+	details := rpc.ContractDetails{}
-
-	buf.WriteString("# NEO-GO specific configuration. Do not modify this unless you know what you are doing!\n")
-	buf.WriteString("neo-go:\n")
-	buf.WriteString("  version: 1.0\n")
-
-	buf.WriteString("\n")
-
-	buf.WriteString("# Project section contains information about your smart contract\n")
-	buf.WriteString("project:\n")
-	buf.WriteString("  author: " + d.Author)
-	buf.WriteString("  email: " + d.Email)
-	buf.WriteString("  version: " + d.Version)
-	buf.WriteString("  name: " + d.ProjectName)
-	buf.WriteString("  description: " + d.Description)
-
-	buf.WriteString("\n")
-
-	buf.WriteString("# Module section contains a list of imported modules\n")
-	buf.WriteString("# This will be automatically managed by the neo-go package manager\n")
-	buf.WriteString("modules: \n")
-	return buf.Bytes()
-}
-
-func parseContractDetails() ContractDetails {
-	details := ContractDetails{}
 	reader := bufio.NewReader(os.Stdin)
 
 	fmt.Print("Author: ")
@@ -282,3 +297,55 @@ func inspect(ctx *cli.Context) error {
 
 	return nil
 }
+
+// contractDeploy deploys contract.
+func contractDeploy(ctx *cli.Context) error {
+	in := ctx.String("in")
+	if len(in) == 0 {
+		return cli.NewExitError(errNoInput, 1)
+	}
+	confFile := ctx.String("config")
+	if len(confFile) == 0 {
+		return cli.NewExitError(errNoConfFile, 1)
+	}
+	endpoint := ctx.String("endpoint")
+	if len(endpoint) == 0 {
+		return cli.NewExitError(errNoEndpoint, 1)
+	}
+	wifStr := ctx.String("wif")
+	if len(wifStr) == 0 {
+		return cli.NewExitError(errNoWIF, 1)
+	}
+	gas := util.Fixed8FromInt64(int64(ctx.Int("gas")))
+
+	wif, err := keys.WIFDecode(wifStr, 0)
+	if err != nil {
+		return cli.NewExitError(fmt.Errorf("bad wif: %v", err), 1)
+	}
+	avm, err := ioutil.ReadFile(in)
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+	confBytes, err := ioutil.ReadFile(confFile)
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+
+	conf := ProjectConfig{}
+	err = yaml.Unmarshal(confBytes, &conf)
+	if err != nil {
+		return cli.NewExitError(fmt.Errorf("bad config: %v", err), 1)
+	}
+
+	client, err := rpc.NewClient(context.TODO(), endpoint, rpc.ClientOptions{})
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+
+	txHash, err := client.DeployContract(avm, &conf.Contract, wif, gas)
+	if err != nil {
+		return cli.NewExitError(fmt.Errorf("failed to deploy: %v", err), 1)
+	}
+	fmt.Printf("Sent deployment transaction %s for contract %s\n", txHash.ReverseString(), hash.Hash160(avm).ReverseString())
+	return nil
+}

pkg/core/account_state.go

@@ -77,6 +77,9 @@ type UnspentBalance struct {
 	Value util.Fixed8  `json:"value"`
 }
 
+// UnspentBalances is a slice of UnspentBalance (mostly needed to sort them).
+type UnspentBalances []UnspentBalance
+
 // AccountState represents the state of a NEO account.
 type AccountState struct {
 	Version    uint8
@@ -156,3 +159,12 @@ func (s *AccountState) GetBalanceValues() map[util.Uint256]util.Fixed8 {
 	}
 	return res
 }
+
+// Len returns the length of UnspentBalances (used to sort things).
+func (us UnspentBalances) Len() int { return len(us) }
+
+// Less compares two elements of UnspentBalances (used to sort things).
+func (us UnspentBalances) Less(i, j int) bool { return us[i].Value < us[j].Value }
+
+// Swap swaps two elements of UnspentBalances (used to sort things).
+func (us UnspentBalances) Swap(i, j int) { us[i], us[j] = us[j], us[i] }

pkg/core/blockchain.go

@@ -943,8 +943,10 @@ func (bc *Blockchain) VerifyTx(t *transaction.Transaction, block *Block) error {
 	if ok := bc.verifyInputs(t); !ok {
 		return errors.New("invalid transaction's inputs")
 	}
-	if ok := bc.memPool.Verify(t); !ok {
+	if block == nil {
-		return errors.New("invalid transaction due to conflicts with the memory pool")
+		if ok := bc.memPool.Verify(t); !ok {
+			return errors.New("invalid transaction due to conflicts with the memory pool")
+		}
 	}
 	if IsDoubleSpend(bc.store, t) {
 		return errors.New("invalid transaction caused by double spending")

pkg/core/transaction/invocation.go

@@ -17,12 +17,13 @@ type InvocationTX struct {
 }
 
 // NewInvocationTX returns a new invocation transaction.
-func NewInvocationTX(script []byte) *Transaction {
+func NewInvocationTX(script []byte, gas util.Fixed8) *Transaction {
 	return &Transaction{
 		Type:    InvocationType,
 		Version: 1,
 		Data: &InvocationTX{
 			Script:  script,
+			Gas:     gas,
 			Version: 1,
 		},
 		Attributes: []*Attribute{},

pkg/core/transaction/transaction_test.go

@@ -98,7 +98,7 @@ func TestDecodeEncodeInvocationTX(t *testing.T) {
 
 func TestNewInvocationTX(t *testing.T) {
 	script := []byte{0x51}
-	tx := NewInvocationTX(script)
+	tx := NewInvocationTX(script, 1)
 	txData := tx.Data.(*InvocationTX)
 	assert.Equal(t, InvocationType, tx.Type)
 	assert.Equal(t, tx.Version, txData.Version)

pkg/rpc/client.go

@@ -11,7 +11,10 @@ import (
 	"sync"
 	"time"
 
+	"github.com/CityOfZion/neo-go/pkg/core"
+	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
+	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/pkg/errors"
 )
 
@@ -152,6 +155,29 @@ func (c *Client) SetClient(cli *http.Client) {
 	}
 }
 
+// CalculateInputs creates input transactions for the specified amount of given
+// asset belonging to specified address. This implementation uses GetUnspents
+// JSON-RPC call internally, so make sure your RPC server suppors that.
+func (c *Client) CalculateInputs(address string, asset util.Uint256, cost util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
+	var utxos core.UnspentBalances
+
+	resp, err := c.GetUnspents(address)
+	if err != nil || resp.Error != nil {
+		if err == nil {
+			err = fmt.Errorf("remote returned %d: %s", resp.Error.Code, resp.Error.Message)
+		}
+		return nil, util.Fixed8(0), errors.Wrapf(err, "cannot get balance for address %v", address)
+	}
+	for _, ubi := range resp.Result.Balance {
+		if asset.Equals(ubi.AssetHash) {
+			utxos = ubi.Unspents
+			break
+		}
+	}
+	return unspentsToInputs(utxos, cost)
+
+}
+
 func (c *Client) performRequest(method string, p params, v interface{}) error {
 	var (
 		r = request{

pkg/rpc/doc.go

@@ -41,6 +41,7 @@ Supported methods
 
 	getblock
 	getaccountstate
+	getunspents
 	invokescript
 	invokefunction
 	sendrawtransaction

pkg/rpc/neoScanBalanceGetter.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"sort"
 
+	"github.com/CityOfZion/neo-go/pkg/core"
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/rpc/wrappers"
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -36,7 +37,6 @@ func (s NeoScanServer) GetBalance(address string) ([]*Unspent, error) {
 	if err = json.NewDecoder(res.Body).Decode(&balance); err != nil {
 		return nil, errs.Wrap(err, "Failed to decode HTTP response")
 	}
-
 	return balance.Balance, nil
 }
 
@@ -55,9 +55,6 @@ func filterSpecificAsset(asset string, balance []*Unspent, assetBalance *Unspent
 func (s NeoScanServer) CalculateInputs(address string, assetIDUint util.Uint256, cost util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
 	var (
 		err          error
-		num, i       uint16
-		required     = cost
-		selected     = util.Fixed8(0)
 		us           []*Unspent
 		assetUnspent Unspent
 		assetID      = wrappers.GlobalAssets[assetIDUint.ReverseString()]
@@ -66,9 +63,19 @@ func (s NeoScanServer) CalculateInputs(address string, assetIDUint util.Uint256,
 		return nil, util.Fixed8(0), errs.Wrapf(err, "Cannot get balance for address %v", address)
 	}
 	filterSpecificAsset(assetID, us, &assetUnspent)
-	sort.Sort(assetUnspent.Unspent)
+	return unspentsToInputs(assetUnspent.Unspent, cost)
+}
 
-	for _, us := range assetUnspent.Unspent {
+// unspentsToInputs uses UnspentBalances to create a slice of inputs for a new
+// transcation containing the required amount of asset.
+func unspentsToInputs(utxos core.UnspentBalances, required util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
+	var (
+		num, i   uint16
+		selected = util.Fixed8(0)
+	)
+	sort.Sort(utxos)
+
+	for _, us := range utxos {
 		if selected >= required {
 			break
 		}
@@ -82,8 +89,8 @@ func (s NeoScanServer) CalculateInputs(address string, assetIDUint util.Uint256,
 	inputs := make([]transaction.Input, 0, num)
 	for i = 0; i < num; i++ {
 		inputs = append(inputs, transaction.Input{
-			PrevHash:  assetUnspent.Unspent[i].TxID,
+			PrevHash:  utxos[i].Tx,
-			PrevIndex: assetUnspent.Unspent[i].N,
+			PrevIndex: utxos[i].Index,
 		})
 	}
 

pkg/rpc/neoScanTypes.go

@@ -1,6 +1,9 @@
 package rpc
 
-import "github.com/CityOfZion/neo-go/pkg/util"
+import (
+	"github.com/CityOfZion/neo-go/pkg/core"
+	"github.com/CityOfZion/neo-go/pkg/util"
+)
 
 /*
 	Definition of types, helper functions and variables
@@ -15,19 +18,9 @@ type (
 		Path string // path to API endpoint without wallet address
 	}
 
-	// UTXO stores unspent TX output for some transaction.
-	UTXO struct {
-		Value util.Fixed8
-		TxID  util.Uint256
-		N     uint16
-	}
-
-	// Unspents is a slice of UTXOs (TODO: drop it?).
-	Unspents []UTXO
-
 	// Unspent stores Unspents per asset
 	Unspent struct {
-		Unspent Unspents
+		Unspent core.UnspentBalances
 		Asset   string      // "NEO" / "GAS"
 		Amount  util.Fixed8 // total unspent of this asset
 	}
@@ -38,8 +31,3 @@ type (
 		Address string
 	}
 )
-
-// functions for sorting array of `Unspents`
-func (us Unspents) Len() int           { return len(us) }
-func (us Unspents) Less(i, j int) bool { return us[i].Value < us[j].Value }
-func (us Unspents) Swap(i, j int)      { us[i], us[j] = us[j], us[i] }

pkg/rpc/rpc.go

@@ -2,9 +2,10 @@ package rpc
 
 import (
 	"encoding/hex"
+	"fmt"
 
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
-	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/pkg/errors"
@@ -39,6 +40,18 @@ func (c *Client) GetAccountState(address string) (*AccountStateResponse, error)
 	return resp, nil
 }
 
+// GetUnspents returns UTXOs for the given NEO account.
+func (c *Client) GetUnspents(address string) (*UnspentResponse, error) {
+	var (
+		params = newParams(address)
+		resp   = &UnspentResponse{}
+	)
+	if err := c.performRequest("getunspents", params, resp); err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
 // InvokeScript returns the result of the given script after running it true the VM.
 // NOTE: This is a test invoke and will not affect the blockchain.
 func (c *Client) InvokeScript(script string) (*InvokeScriptResponse, error) {
@@ -96,9 +109,9 @@ func (c *Client) Invoke(script string, params []smartcontract.Parameter) (*Invok
 // The given hex string needs to be signed with a keypair.
 // When the result of the response object is true, the TX has successfully
 // been broadcasted to the network.
-func (c *Client) sendRawTransaction(rawTX string) (*response, error) {
+func (c *Client) sendRawTransaction(rawTX *transaction.Transaction) (*response, error) {
 	var (
-		params = newParams(rawTX)
+		params = newParams(hex.EncodeToString(rawTX.Bytes()))
 		resp   = &response{}
 	)
 	if err := c.performRequest("sendrawtransaction", params, resp); err != nil {
@@ -113,9 +126,7 @@ func (c *Client) sendRawTransaction(rawTX string) (*response, error) {
 func (c *Client) SendToAddress(asset util.Uint256, address string, amount util.Fixed8) (*SendToAddressResponse, error) {
 	var (
 		err      error
-		buf      = io.NewBufBinWriter()
 		rawTx    *transaction.Transaction
-		rawTxStr string
 		txParams = ContractTxParams{
 			assetID:  asset,
 			address:  address,
@@ -130,12 +141,7 @@ func (c *Client) SendToAddress(asset util.Uint256, address string, amount util.F
 	if rawTx, err = CreateRawContractTransaction(txParams); err != nil {
 		return nil, errors.Wrap(err, "failed to create raw transaction for `sendtoaddress`")
 	}
-	rawTx.EncodeBinary(buf.BinWriter)
+	if resp, err = c.sendRawTransaction(rawTx); err != nil {
-	if buf.Err != nil {
-		return nil, errors.Wrap(buf.Err, "failed to encode raw transaction to binary for `sendtoaddress`")
-	}
-	rawTxStr = hex.EncodeToString(buf.Bytes())
-	if resp, err = c.sendRawTransaction(rawTxStr); err != nil {
 		return nil, errors.Wrap(err, "failed to send raw transaction")
 	}
 	response.Error = resp.Error
@@ -146,3 +152,39 @@ func (c *Client) SendToAddress(asset util.Uint256, address string, amount util.F
 	}
 	return response, nil
 }
+
+// DeployContract deploys given contract to the blockchain using given wif to
+// sign the transaction and spending the amount of gas specified. It returns
+// a hash of the deployment transaction and an error.
+func (c *Client) DeployContract(avm []byte, contract *ContractDetails, wif *keys.WIF, gas util.Fixed8) (util.Uint256, error) {
+	var txHash util.Uint256
+
+	gasIDB, _ := hex.DecodeString("602c79718b16e442de58778e148d0b1084e3b2dffd5de6b7b16cee7969282de7")
+	gasID, _ := util.Uint256DecodeReverseBytes(gasIDB)
+
+	txScript, err := CreateDeploymentScript(avm, contract)
+	if err != nil {
+		return txHash, errors.Wrap(err, "failed creating deployment script")
+	}
+	tx := transaction.NewInvocationTX(txScript, gas)
+
+	fromAddress := wif.PrivateKey.Address()
+
+	if err = AddInputsAndUnspentsToTx(tx, fromAddress, gasID, gas, c); err != nil {
+		return txHash, errors.Wrap(err, "failed to add inputs and unspents to transaction")
+	}
+
+	if err = SignTx(tx, wif); err != nil {
+		return txHash, errors.Wrap(err, "failed to sign tx")
+	}
+	txHash = tx.Hash()
+	resp, err := c.sendRawTransaction(tx)
+
+	if err != nil {
+		return txHash, errors.Wrap(err, "failed sendning tx")
+	}
+	if resp.Error != nil {
+		return txHash, fmt.Errorf("remote returned %d: %s", resp.Error.Code, resp.Error.Message)
+	}
+	return txHash, nil
+}

pkg/rpc/scdetails.go

@@ -0,0 +1,15 @@
+package rpc
+
+// ContractDetails contains contract metadata.
+type ContractDetails struct {
+	Author               string
+	Email                string
+	Version              string
+	ProjectName          string `yaml:"name"`
+	Description          string
+	HasStorage           bool
+	HasDynamicInvocation bool
+	IsPayable            bool
+	ReturnType           StackParamType
+	Parameters           []StackParamType
+}

pkg/rpc/stack_param.go

@@ -103,6 +103,23 @@ func (t *StackParamType) UnmarshalJSON(data []byte) (err error) {
 	return
 }
 
+// MarshalYAML implements the YAML Marshaler interface.
+func (t *StackParamType) MarshalYAML() (interface{}, error) {
+	return t.String(), nil
+}
+
+// UnmarshalYAML implements the YAML Unmarshaler interface.
+func (t *StackParamType) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var name string
+
+	err := unmarshal(&name)
+	if err != nil {
+		return err
+	}
+	*t, err = StackParamTypeFromString(name)
+	return err
+}
+
 // StackParam represent a stack parameter.
 type StackParam struct {
 	Type  StackParamType `json:"type"`

pkg/rpc/txBuilder.go

@@ -1,11 +1,15 @@
 package rpc
 
 import (
+	"bytes"
+
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/crypto"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm"
 	errs "github.com/pkg/errors"
 )
 
@@ -16,10 +20,7 @@ func CreateRawContractTransaction(params ContractTxParams) (*transaction.Transac
 		tx                             = transaction.NewContractTX()
 		toAddressHash, fromAddressHash util.Uint160
 		fromAddress                    string
-		senderOutput, receiverOutput   *transaction.Output
+		receiverOutput                 *transaction.Output
-		inputs                         []transaction.Input
-		spent                          util.Fixed8
-		witness                        transaction.Witness
 
 		wif, assetID, address, amount, balancer = params.wif, params.assetID, params.address, params.value, params.balancer
 	)
@@ -39,32 +40,57 @@ func CreateRawContractTransaction(params ContractTxParams) (*transaction.Transac
 			Data:  fromAddressHash.Bytes(),
 		})
 
-	if inputs, spent, err = balancer.CalculateInputs(fromAddress, assetID, amount); err != nil {
+	if err = AddInputsAndUnspentsToTx(tx, fromAddress, assetID, amount, balancer); err != nil {
-		return nil, errs.Wrap(err, "Failed to get inputs for transaction")
+		return nil, errs.Wrap(err, "failed to add inputs and unspents to transaction")
+	}
+	receiverOutput = transaction.NewOutput(assetID, amount, toAddressHash)
+	tx.AddOutput(receiverOutput)
+	if err = SignTx(tx, &wif); err != nil {
+		return nil, errs.Wrap(err, "failed to sign tx")
+	}
+
+	return tx, nil
+}
+
+// AddInputsAndUnspentsToTx adds inputs needed to transaction and one output
+// with change.
+func AddInputsAndUnspentsToTx(tx *transaction.Transaction, address string, assetID util.Uint256, amount util.Fixed8, balancer BalanceGetter) error {
+	scriptHash, err := crypto.Uint160DecodeAddress(address)
+	if err != nil {
+		return errs.Wrapf(err, "failed to take script hash from address: %v", address)
+	}
+	inputs, spent, err := balancer.CalculateInputs(address, assetID, amount)
+	if err != nil {
+		return errs.Wrap(err, "failed to get inputs")
 	}
 	for _, input := range inputs {
 		tx.AddInput(&input)
 	}
 
 	if senderUnspent := spent - amount; senderUnspent > 0 {
-		senderOutput = transaction.NewOutput(assetID, senderUnspent, fromAddressHash)
+		senderOutput := transaction.NewOutput(assetID, senderUnspent, scriptHash)
 		tx.AddOutput(senderOutput)
 	}
-	receiverOutput = transaction.NewOutput(assetID, amount, toAddressHash)
+	return nil
-	tx.AddOutput(receiverOutput)
+}
+
+// SignTx signs given transaction in-place using given key.
+func SignTx(tx *transaction.Transaction, wif *keys.WIF) error {
+	var witness transaction.Witness
+	var err error
 
 	if witness.InvocationScript, err = GetInvocationScript(tx, wif); err != nil {
-		return nil, errs.Wrap(err, "Failed to create invocation script")
+		return errs.Wrap(err, "failed to create invocation script")
 	}
 	witness.VerificationScript = wif.GetVerificationScript()
 	tx.Scripts = append(tx.Scripts, &witness)
 	tx.Hash()
 
-	return tx, nil
+	return nil
 }
 
 // GetInvocationScript returns NEO VM script containing transaction signature.
-func GetInvocationScript(tx *transaction.Transaction, wif keys.WIF) ([]byte, error) {
+func GetInvocationScript(tx *transaction.Transaction, wif *keys.WIF) ([]byte, error) {
 	const (
 		pushbytes64 = 0x40
 	)
@@ -84,3 +110,55 @@ func GetInvocationScript(tx *transaction.Transaction, wif keys.WIF) ([]byte, err
 	}
 	return append([]byte{pushbytes64}, signature...), nil
 }
+
+// CreateDeploymentScript returns a script that deploys given smart contract
+// with its metadata.
+func CreateDeploymentScript(avm []byte, contract *ContractDetails) ([]byte, error) {
+	var props smartcontract.PropertyState
+
+	script := new(bytes.Buffer)
+	if err := vm.EmitBytes(script, []byte(contract.Description)); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitBytes(script, []byte(contract.Email)); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitBytes(script, []byte(contract.Author)); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitBytes(script, []byte(contract.Version)); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitBytes(script, []byte(contract.ProjectName)); err != nil {
+		return nil, err
+	}
+	if contract.HasStorage {
+		props |= smartcontract.HasStorage
+	}
+	if contract.HasDynamicInvocation {
+		props |= smartcontract.HasDynamicInvoke
+	}
+	if contract.IsPayable {
+		props |= smartcontract.IsPayable
+	}
+	if err := vm.EmitInt(script, int64(props)); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitInt(script, int64(contract.ReturnType)); err != nil {
+		return nil, err
+	}
+	params := make([]byte, len(contract.Parameters))
+	for k := range contract.Parameters {
+		params[k] = byte(contract.Parameters[k])
+	}
+	if err := vm.EmitBytes(script, params); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitBytes(script, avm); err != nil {
+		return nil, err
+	}
+	if err := vm.EmitSyscall(script, "Neo.Contract.Create"); err != nil {
+		return nil, err
+	}
+	return script.Bytes(), nil
+}

pkg/rpc/types.go

@@ -2,6 +2,7 @@ package rpc
 
 import (
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
+	"github.com/CityOfZion/neo-go/pkg/rpc/wrappers"
 	"github.com/CityOfZion/neo-go/pkg/vm"
 )
 
@@ -27,6 +28,13 @@ type AccountStateResponse struct {
 	Result *Account `json:"result"`
 }
 
+// UnspentResponse represents server response to the `getunspents` command.
+type UnspentResponse struct {
+	responseHeader
+	Error  *Error             `json:"error,omitempty"`
+	Result *wrappers.Unspents `json:"result,omitempty"`
+}
+
 // Account represents details about a NEO account.
 type Account struct {
 	Version    int    `json:"version"`