neo-go/pkg/core/transaction/transaction.go
2021-05-17 13:43:03 +03:00

399 lines
11 KiB
Go

package transaction
import (
"encoding/json"
"errors"
"fmt"
"math"
"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"
)
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.
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
// 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,
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.hash.Equals(util.Uint256{}) {
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) {
t.Version = uint8(br.ReadB())
t.Nonce = br.ReadU32LE()
t.SystemFee = int64(br.ReadU64LE())
t.NetworkFee = int64(br.ReadU64LE())
t.ValidUntilBlock = br.ReadU32LE()
br.ReadArray(&t.Signers, MaxAttributes)
br.ReadArray(&t.Attributes, MaxAttributes-len(t.Signers))
t.Script = br.ReadVarBytes(MaxScriptLength)
if br.Err == nil {
br.Err = t.isValid()
}
}
// DecodeBinary implements Serializable interface.
func (t *Transaction) DecodeBinary(br *io.BinReader) {
t.decodeHashableFields(br)
if br.Err != nil {
return
}
br.ReadArray(&t.Scripts, len(t.Signers))
if len(t.Signers) != len(t.Scripts) {
br.Err = fmt.Errorf("%w: %d vs %d", ErrInvalidWitnessNum, len(t.Signers), len(t.Scripts))
return
}
// Create the hash of the transaction at decode, so we dont need
// to do it anymore.
if br.Err == nil {
br.Err = t.createHash()
_ = t.Size()
}
}
// EncodeBinary implements Serializable interface.
func (t *Transaction) EncodeBinary(bw *io.BinWriter) {
t.encodeHashableFields(bw)
bw.WriteArray(t.Scripts)
}
// 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) {
if len(t.Script) == 0 {
bw.Err = errors.New("transaction has no script")
return
}
bw.WriteB(byte(t.Version))
bw.WriteU32LE(t.Nonce)
bw.WriteU64LE(uint64(t.SystemFee))
bw.WriteU64LE(uint64(t.NetworkFee))
bw.WriteU32LE(t.ValidUntilBlock)
bw.WriteArray(t.Signers)
bw.WriteArray(t.Attributes)
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 {
buf := io.NewBufBinWriter()
t.encodeHashableFields(buf.BinWriter)
if buf.Err != nil {
return buf.Err
}
t.hash = hash.Sha256(buf.Bytes())
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)
if r.Err != nil {
return r.Err
}
// Ensure all the data was read.
_ = r.ReadB()
if r.Err == nil {
return errors.New("additional data after the signed part")
}
t.Scripts = make([]Witness, 0)
t.hash = hash.Sha256(buf)
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.DecodeBinary(r)
if r.Err != nil {
return nil, r.Err
}
_ = r.ReadB()
if r.Err == nil {
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 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 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
}