/
transaction.go
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/
transaction.go
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package transaction
import (
"crypto/sha256"
"encoding/json"
"errors"
"fmt"
"math"
"math/big"
"math/rand"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/encoding/address"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
const (
// MaxScriptLength is the limit for transaction's script length.
MaxScriptLength = math.MaxUint16
// MaxTransactionSize is the upper limit size in bytes that a transaction can reach. It is
// set to be 102400.
MaxTransactionSize = 102400
// MaxAttributes is maximum number of attributes including signers that can be contained
// within a transaction. It is set to be 16.
MaxAttributes = 16
// DummyVersion represents reserved transaction version for trimmed transactions.
DummyVersion = 255
)
// ErrInvalidWitnessNum returns when the number of witnesses does not match signers.
var ErrInvalidWitnessNum = errors.New("number of signers doesn't match witnesses")
// Transaction is a process recorded in the Neo blockchain.
type Transaction struct {
// The trading version which is currently 0.
Version uint8
// Random number to avoid hash collision.
Nonce uint32
// Fee to be burned.
SystemFee int64
// Fee to be distributed to consensus nodes.
NetworkFee int64
// Maximum blockchain height exceeding which
// transaction should fail verification. E.g. if VUB=N, then transaction
// can be accepted to block with index N, but not to block with index N+1.
ValidUntilBlock uint32
// Code to run in NeoVM for this transaction.
Script []byte
// Transaction attributes.
Attributes []Attribute
// Transaction signers list (starts with Sender).
Signers []Signer
// The scripts that comes with this transaction.
// Scripts exist out of the verification script
// and invocation script.
Scripts []Witness
// size is transaction's serialized size.
size int
// Hash of the transaction (double SHA256).
hash util.Uint256
// Whether hash is correct.
hashed bool
// Trimmed indicates this is a transaction from trimmed
// data.
Trimmed bool
}
// NewTrimmedTX returns a trimmed transaction with only its hash
// and Trimmed to true.
func NewTrimmedTX(hash util.Uint256) *Transaction {
return &Transaction{
hash: hash,
hashed: true,
Trimmed: true,
}
}
// New returns a new transaction to execute given script and pay given system
// fee.
func New(script []byte, gas int64) *Transaction {
return &Transaction{
Version: 0,
Nonce: rand.Uint32(),
Script: script,
SystemFee: gas,
Attributes: []Attribute{},
Signers: []Signer{},
Scripts: []Witness{},
}
}
// Hash returns the hash of the transaction.
func (t *Transaction) Hash() util.Uint256 {
if !t.hashed {
if t.createHash() != nil {
panic("failed to compute hash!")
}
}
return t.hash
}
// HasAttribute returns true iff t has an attribute of type typ.
func (t *Transaction) HasAttribute(typ AttrType) bool {
for i := range t.Attributes {
if t.Attributes[i].Type == typ {
return true
}
}
return false
}
// GetAttributes returns the list of transaction's attributes of the given type.
// Returns nil in case if attributes not found.
func (t *Transaction) GetAttributes(typ AttrType) []Attribute {
var result []Attribute
for _, attr := range t.Attributes {
if attr.Type == typ {
result = append(result, attr)
}
}
return result
}
// decodeHashableFields decodes the fields that are used for signing the
// transaction, which are all fields except the scripts.
func (t *Transaction) decodeHashableFields(br *io.BinReader, buf []byte) {
var start, end int
if buf != nil {
start = len(buf) - br.Len()
}
t.Version = uint8(br.ReadB())
t.Nonce = br.ReadU32LE()
t.SystemFee = int64(br.ReadU64LE())
t.NetworkFee = int64(br.ReadU64LE())
t.ValidUntilBlock = br.ReadU32LE()
nsigners := br.ReadVarUint()
if br.Err != nil {
return
}
if nsigners > MaxAttributes {
br.Err = errors.New("too many signers")
return
} else if nsigners == 0 {
br.Err = errors.New("missing signers")
return
}
t.Signers = make([]Signer, nsigners)
for i := 0; i < int(nsigners); i++ {
t.Signers[i].DecodeBinary(br)
}
nattrs := br.ReadVarUint()
if nattrs > MaxAttributes-nsigners {
br.Err = errors.New("too many attributes")
return
}
t.Attributes = make([]Attribute, nattrs)
for i := 0; i < int(nattrs); i++ {
t.Attributes[i].DecodeBinary(br)
}
t.Script = br.ReadVarBytes(MaxScriptLength)
if br.Err == nil {
br.Err = t.isValid()
}
if buf != nil {
end = len(buf) - br.Len()
t.hash = hash.Sha256(buf[start:end])
t.hashed = true
}
}
func (t *Transaction) decodeBinaryNoSize(br *io.BinReader, buf []byte) {
t.decodeHashableFields(br, buf)
if br.Err != nil {
return
}
nscripts := br.ReadVarUint()
if nscripts > MaxAttributes {
br.Err = errors.New("too many witnesses")
return
} else if int(nscripts) != len(t.Signers) {
br.Err = fmt.Errorf("%w: %d vs %d", ErrInvalidWitnessNum, len(t.Signers), nscripts)
return
}
t.Scripts = make([]Witness, nscripts)
for i := 0; i < int(nscripts); i++ {
t.Scripts[i].DecodeBinary(br)
}
// Create the hash of the transaction at decode, so we dont need
// to do it anymore.
if br.Err == nil && buf == nil {
br.Err = t.createHash()
}
}
// DecodeBinary implements the Serializable interface.
func (t *Transaction) DecodeBinary(br *io.BinReader) {
t.decodeBinaryNoSize(br, nil)
if br.Err == nil {
_ = t.Size()
}
}
// EncodeBinary implements the Serializable interface.
func (t *Transaction) EncodeBinary(bw *io.BinWriter) {
t.encodeHashableFields(bw)
bw.WriteVarUint(uint64(len(t.Scripts)))
for i := range t.Scripts {
t.Scripts[i].EncodeBinary(bw)
}
}
// encodeHashableFields encodes the fields that are not used for
// signing the transaction, which are all fields except the scripts.
func (t *Transaction) encodeHashableFields(bw *io.BinWriter) {
bw.WriteB(byte(t.Version))
bw.WriteU32LE(t.Nonce)
bw.WriteU64LE(uint64(t.SystemFee))
bw.WriteU64LE(uint64(t.NetworkFee))
bw.WriteU32LE(t.ValidUntilBlock)
bw.WriteVarUint(uint64(len(t.Signers)))
for i := range t.Signers {
t.Signers[i].EncodeBinary(bw)
}
bw.WriteVarUint(uint64(len(t.Attributes)))
for i := range t.Attributes {
t.Attributes[i].EncodeBinary(bw)
}
bw.WriteVarBytes(t.Script)
}
// EncodeHashableFields returns serialized transaction's fields which are hashed.
func (t *Transaction) EncodeHashableFields() ([]byte, error) {
bw := io.NewBufBinWriter()
t.encodeHashableFields(bw.BinWriter)
if bw.Err != nil {
return nil, bw.Err
}
return bw.Bytes(), nil
}
// createHash creates the hash of the transaction.
func (t *Transaction) createHash() error {
shaHash := sha256.New()
bw := io.NewBinWriterFromIO(shaHash)
t.encodeHashableFields(bw)
if bw.Err != nil {
return bw.Err
}
shaHash.Sum(t.hash[:0])
t.hashed = true
return nil
}
// DecodeHashableFields decodes a part of transaction which should be hashed.
func (t *Transaction) DecodeHashableFields(buf []byte) error {
r := io.NewBinReaderFromBuf(buf)
t.decodeHashableFields(r, buf)
if r.Err != nil {
return r.Err
}
// Ensure all the data was read.
if r.Len() != 0 {
return errors.New("additional data after the signed part")
}
t.Scripts = make([]Witness, 0)
return nil
}
// Bytes converts the transaction to []byte.
func (t *Transaction) Bytes() []byte {
buf := io.NewBufBinWriter()
t.EncodeBinary(buf.BinWriter)
if buf.Err != nil {
return nil
}
return buf.Bytes()
}
// NewTransactionFromBytes decodes byte array into *Transaction.
func NewTransactionFromBytes(b []byte) (*Transaction, error) {
tx := &Transaction{}
r := io.NewBinReaderFromBuf(b)
tx.decodeBinaryNoSize(r, b)
if r.Err != nil {
return nil, r.Err
}
if r.Len() != 0 {
return nil, errors.New("additional data after the transaction")
}
tx.size = len(b)
return tx, nil
}
// FeePerByte returns NetworkFee of the transaction divided by
// its size.
func (t *Transaction) FeePerByte() int64 {
return t.NetworkFee / int64(t.Size())
}
// Size returns size of the serialized transaction.
func (t *Transaction) Size() int {
if t.size == 0 {
t.size = io.GetVarSize(t)
}
return t.size
}
// Sender returns the sender of the transaction which is always on the first place
// in the transaction's signers list.
func (t *Transaction) Sender() util.Uint160 {
if len(t.Signers) == 0 {
panic("transaction does not have signers")
}
return t.Signers[0].Account
}
// transactionJSON is a wrapper for Transaction and
// used for correct marhalling of transaction.Data.
type transactionJSON struct {
TxID util.Uint256 `json:"hash"`
Size int `json:"size"`
Version uint8 `json:"version"`
Nonce uint32 `json:"nonce"`
Sender string `json:"sender"`
SystemFee int64 `json:"sysfee,string"`
NetworkFee int64 `json:"netfee,string"`
ValidUntilBlock uint32 `json:"validuntilblock"`
Attributes []Attribute `json:"attributes"`
Signers []Signer `json:"signers"`
Script []byte `json:"script"`
Scripts []Witness `json:"witnesses"`
}
// MarshalJSON implements the json.Marshaler interface.
func (t *Transaction) MarshalJSON() ([]byte, error) {
tx := transactionJSON{
TxID: t.Hash(),
Size: t.Size(),
Version: t.Version,
Nonce: t.Nonce,
Sender: address.Uint160ToString(t.Sender()),
ValidUntilBlock: t.ValidUntilBlock,
Attributes: t.Attributes,
Signers: t.Signers,
Script: t.Script,
Scripts: t.Scripts,
SystemFee: t.SystemFee,
NetworkFee: t.NetworkFee,
}
return json.Marshal(tx)
}
// UnmarshalJSON implements the json.Unmarshaler interface.
func (t *Transaction) UnmarshalJSON(data []byte) error {
tx := new(transactionJSON)
if err := json.Unmarshal(data, tx); err != nil {
return err
}
t.Version = tx.Version
t.Nonce = tx.Nonce
t.ValidUntilBlock = tx.ValidUntilBlock
t.Attributes = tx.Attributes
t.Signers = tx.Signers
t.Scripts = tx.Scripts
t.SystemFee = tx.SystemFee
t.NetworkFee = tx.NetworkFee
t.Script = tx.Script
if t.Hash() != tx.TxID {
return errors.New("txid doesn't match transaction hash")
}
if t.Size() != tx.Size {
return errors.New("'size' doesn't match transaction size")
}
return t.isValid()
}
// Various errors for transaction validation.
var (
ErrInvalidVersion = errors.New("only version 0 is supported")
ErrNegativeSystemFee = errors.New("negative system fee")
ErrNegativeNetworkFee = errors.New("negative network fee")
ErrTooBigFees = errors.New("too big fees: int64 overflow")
ErrEmptySigners = errors.New("signers array should contain sender")
ErrNonUniqueSigners = errors.New("transaction signers should be unique")
ErrInvalidAttribute = errors.New("invalid attribute")
ErrEmptyScript = errors.New("no script")
)
// isValid checks whether decoded/unmarshalled transaction has all fields valid.
func (t *Transaction) isValid() error {
if t.Version > 0 && t.Version != DummyVersion {
return ErrInvalidVersion
}
if t.SystemFee < 0 {
return ErrNegativeSystemFee
}
if t.NetworkFee < 0 {
return ErrNegativeNetworkFee
}
if t.NetworkFee+t.SystemFee < t.SystemFee {
return ErrTooBigFees
}
if len(t.Signers) == 0 {
return ErrEmptySigners
}
for i := 0; i < len(t.Signers); i++ {
for j := i + 1; j < len(t.Signers); j++ {
if t.Signers[i].Account.Equals(t.Signers[j].Account) {
return ErrNonUniqueSigners
}
}
}
attrs := map[AttrType]bool{}
for i := range t.Attributes {
typ := t.Attributes[i].Type
if !typ.allowMultiple() {
if attrs[typ] {
return fmt.Errorf("%w: multiple '%s' attributes", ErrInvalidAttribute, typ.String())
}
attrs[typ] = true
}
}
if len(t.Script) == 0 {
return ErrEmptyScript
}
return nil
}
// HasSigner returns true in case if hash is present in the list of signers.
func (t *Transaction) HasSigner(hash util.Uint160) bool {
for _, h := range t.Signers {
if h.Account.Equals(hash) {
return true
}
}
return false
}
// ToStackItem converts Transaction to stackitem.Item.
func (t *Transaction) ToStackItem() stackitem.Item {
return stackitem.NewArray([]stackitem.Item{
stackitem.NewByteArray(t.Hash().BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(t.Version))),
stackitem.NewBigInteger(big.NewInt(int64(t.Nonce))),
stackitem.NewByteArray(t.Sender().BytesBE()),
stackitem.NewBigInteger(big.NewInt(int64(t.SystemFee))),
stackitem.NewBigInteger(big.NewInt(int64(t.NetworkFee))),
stackitem.NewBigInteger(big.NewInt(int64(t.ValidUntilBlock))),
stackitem.NewByteArray(t.Script),
})
}