package transaction import ( "crypto/sha256" "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() 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() } } func (t *Transaction) decodeBinaryNoSize(br *io.BinReader) { t.decodeHashableFields(br) 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), len(t.Scripts)) 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 { br.Err = t.createHash() } } // DecodeBinary implements Serializable interface. func (t *Transaction) DecodeBinary(br *io.BinReader) { t.decodeBinaryNoSize(br) if br.Err == nil { _ = t.Size() } } // EncodeBinary implements 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) { 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.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]) 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.decodeBinaryNoSize(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 }