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transaction.ts
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transaction.ts
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/* eslint-disable no-dupe-class-members */
import { Buffer } from 'buffer'
import {
Address,
BN,
bnToHex,
bnToRlp,
ecrecover,
ecsign,
rlp,
rlphash,
toBuffer,
unpadBuffer,
publicToAddress,
MAX_INTEGER,
} from 'ethereumjs-util'
import Common from '@ethereumjs/common'
import { TxOptions, TxData, JsonTx } from './types'
// secp256k1n/2
const N_DIV_2 = new BN('7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0', 16)
/**
* An Ethereum transaction.
*/
export default class Transaction {
public readonly common: Common
public readonly nonce: BN
public readonly gasLimit: BN
public readonly gasPrice: BN
public readonly to?: Address
public readonly value: BN
public readonly data: Buffer
public readonly v?: BN
public readonly r?: BN
public readonly s?: BN
public static fromTxData(txData: TxData, opts?: TxOptions) {
return new Transaction(txData, opts)
}
public static fromRlpSerializedTx(serialized: Buffer, opts?: TxOptions) {
const values = rlp.decode(serialized)
if (!Array.isArray(values)) {
throw new Error('Invalid serialized tx input. Must be array')
}
return this.fromValuesArray(values, opts)
}
public static fromValuesArray(values: Buffer[], opts?: TxOptions) {
if (values.length !== 6 && values.length !== 9) {
throw new Error(
'Invalid transaction. Only expecting 6 values (for unsigned tx) or 9 values (for signed tx).'
)
}
const [nonce, gasPrice, gasLimit, to, value, data, v, r, s] = values
const emptyBuffer = Buffer.from([])
return new Transaction(
{
nonce: new BN(nonce),
gasPrice: new BN(gasPrice),
gasLimit: new BN(gasLimit),
to: to && to.length > 0 ? new Address(to) : undefined,
value: new BN(value),
data: data ?? emptyBuffer,
v: !v?.equals(emptyBuffer) ? new BN(v) : undefined,
r: !r?.equals(emptyBuffer) ? new BN(r) : undefined,
s: !s?.equals(emptyBuffer) ? new BN(s) : undefined,
},
opts
)
}
/**
* This constructor takes the values, validates them, assigns them and freezes the object.
* Use the static factory methods to assist in creating a Transaction object from varying data types.
* @note Transaction objects implement EIP155 by default. To disable it, pass in an `@ethereumjs/common` object set before EIP155 activation (i.e. before Spurious Dragon).
*/
constructor(txData: TxData, opts?: TxOptions) {
const { nonce, gasPrice, gasLimit, to, value, data, v, r, s } = txData
this.nonce = new BN(toBuffer(nonce))
this.gasPrice = new BN(toBuffer(gasPrice))
this.gasLimit = new BN(toBuffer(gasLimit))
this.to = to ? new Address(toBuffer(to)) : undefined
this.value = new BN(toBuffer(value))
this.data = toBuffer(data)
this.v = v ? new BN(toBuffer(v)) : undefined
this.r = r ? new BN(toBuffer(r)) : undefined
this.s = s ? new BN(toBuffer(s)) : undefined
const validateCannotExceedMaxInteger = {
nonce: this.nonce,
gasPrice: this.gasPrice,
gasLimit: this.gasLimit,
value: this.value,
r: this.r,
s: this.s,
}
for (const [key, value] of Object.entries(validateCannotExceedMaxInteger)) {
if (value && value.gt(MAX_INTEGER)) {
throw new Error(`${key} cannot exceed MAX_INTEGER, given ${value}`)
}
}
if (opts?.common) {
this.common = Object.assign(Object.create(Object.getPrototypeOf(opts.common)), opts.common)
} else {
const DEFAULT_CHAIN = 'mainnet'
this.common = new Common({ chain: DEFAULT_CHAIN })
}
this._validateTxV(this.v)
const freeze = opts?.freeze ?? true
if (freeze) {
Object.freeze(this)
}
}
/**
* If the tx's `to` is to the creation address
*/
toCreationAddress(): boolean {
return this.to === undefined || this.to.buf.length === 0
}
/**
* Computes a sha3-256 hash of the serialized tx
*/
hash(): Buffer {
const values = [
bnToRlp(this.nonce),
bnToRlp(this.gasPrice),
bnToRlp(this.gasLimit),
this.to !== undefined ? this.to.buf : Buffer.from([]),
bnToRlp(this.value),
this.data,
this.v ? bnToRlp(this.v) : Buffer.from([]),
this.r ? bnToRlp(this.r) : Buffer.from([]),
this.s ? bnToRlp(this.s) : Buffer.from([]),
]
return rlphash(values)
}
getMessageToSign() {
return this._getMessageToSign(this._unsignedTxImplementsEIP155())
}
getMessageToVerifySignature() {
return this._getMessageToSign(this._signedTxImplementsEIP155())
}
/**
* Returns chain ID
*/
getChainId(): number {
return this.common.chainId()
}
/**
* Returns the sender's address
*/
getSenderAddress(): Address {
return new Address(publicToAddress(this.getSenderPublicKey()))
}
/**
* Returns the public key of the sender
*/
getSenderPublicKey(): Buffer {
const msgHash = this.getMessageToVerifySignature()
// All transaction signatures whose s-value is greater than secp256k1n/2 are considered invalid.
if (this.common.gteHardfork('homestead') && this.s && this.s.gt(N_DIV_2)) {
throw new Error(
'Invalid Signature: s-values greater than secp256k1n/2 are considered invalid'
)
}
const { v, r, s } = this
if (!v || !r || !s) {
throw new Error('Missing values to derive sender public key from signed tx')
}
try {
return ecrecover(
msgHash,
v.toNumber(),
bnToRlp(r),
bnToRlp(s),
this._signedTxImplementsEIP155() ? this.getChainId() : undefined
)
} catch (e) {
throw new Error('Invalid Signature')
}
}
/**
* Determines if the signature is valid
*/
verifySignature(): boolean {
try {
// Main signature verification is done in `getSenderPublicKey()`
const publicKey = this.getSenderPublicKey()
return unpadBuffer(publicKey).length !== 0
} catch (e) {
return false
}
}
/**
* Sign a transaction with a given private key.
* Returns a new Transaction object (the original tx will not be modified).
* Example:
* ```typescript
* const unsignedTx = Transaction.fromTxData(txData)
* const signedTx = unsignedTx.sign(privKey)
* ```
* @param privateKey Must be 32 bytes in length.
*/
sign(privateKey: Buffer) {
if (privateKey.length !== 32) {
throw new Error('Private key must be 32 bytes in length.')
}
const msgHash = this.getMessageToSign()
// Only `v` is reassigned.
/* eslint-disable-next-line prefer-const */
let { v, r, s } = ecsign(msgHash, privateKey)
if (this._unsignedTxImplementsEIP155()) {
v += this.getChainId() * 2 + 8
}
const opts = {
common: this.common,
}
return new Transaction(
{
nonce: this.nonce,
gasPrice: this.gasPrice,
gasLimit: this.gasLimit,
to: this.to,
value: this.value,
data: this.data,
v: new BN(v),
r: new BN(r),
s: new BN(s),
},
opts
)
}
/**
* The amount of gas paid for the data in this tx
*/
getDataFee(): BN {
const txDataZero = this.common.param('gasPrices', 'txDataZero')
const txDataNonZero = this.common.param('gasPrices', 'txDataNonZero')
let cost = 0
for (let i = 0; i < this.data.length; i++) {
this.data[i] === 0 ? (cost += txDataZero) : (cost += txDataNonZero)
}
return new BN(cost)
}
/**
* The minimum amount of gas the tx must have (DataFee + TxFee + Creation Fee)
*/
getBaseFee(): BN {
const fee = this.getDataFee().addn(this.common.param('gasPrices', 'tx'))
if (this.common.gteHardfork('homestead') && this.toCreationAddress()) {
fee.iaddn(this.common.param('gasPrices', 'txCreation'))
}
return fee
}
/**
* The up front amount that an account must have for this transaction to be valid
*/
getUpfrontCost(): BN {
return this.gasLimit.mul(this.gasPrice).add(this.value)
}
/**
* Validates the signature and checks if
* the transaction has the minimum amount of gas required
* (DataFee + TxFee + Creation Fee).
*/
validate(): boolean
validate(stringError: false): boolean
validate(stringError: true): string[]
validate(stringError: boolean = false): boolean | string[] {
const errors = []
if (!this.verifySignature()) {
errors.push('Invalid Signature')
}
if (this.getBaseFee().gt(this.gasLimit)) {
errors.push(`gasLimit is too low. given ${this.gasLimit}, need at least ${this.getBaseFee()}`)
}
return stringError ? errors : errors.length === 0
}
/**
* Returns a Buffer Array of the raw Buffers of this transaction, in order.
*/
raw(): Buffer[] {
return [
bnToRlp(this.nonce),
bnToRlp(this.gasPrice),
bnToRlp(this.gasLimit),
this.to !== undefined ? this.to.buf : Buffer.from([]),
bnToRlp(this.value),
this.data,
this.v !== undefined ? bnToRlp(this.v) : Buffer.from([]),
this.r !== undefined ? bnToRlp(this.r) : Buffer.from([]),
this.s !== undefined ? bnToRlp(this.s) : Buffer.from([]),
]
}
/**
* Returns the rlp encoding of the transaction.
*/
serialize(): Buffer {
return rlp.encode(this.raw())
}
/**
* Returns an object with the JSON representation of the transaction
*/
toJSON(): JsonTx {
return {
nonce: bnToHex(this.nonce),
gasPrice: bnToHex(this.gasPrice),
gasLimit: bnToHex(this.gasLimit),
to: this.to !== undefined ? this.to.toString() : undefined,
value: bnToHex(this.value),
data: '0x' + this.data.toString('hex'),
v: this.v !== undefined ? bnToHex(this.v) : undefined,
r: this.r !== undefined ? bnToHex(this.r) : undefined,
s: this.s !== undefined ? bnToHex(this.s) : undefined,
}
}
public isSigned(): boolean {
const { v, r, s } = this
return !!v && !!r && !!s
}
private _unsignedTxImplementsEIP155() {
return this.common.gteHardfork('spuriousDragon')
}
private _signedTxImplementsEIP155() {
if (!this.isSigned()) {
throw Error('This transaction is not signed')
}
const onEIP155BlockOrLater = this.common.gteHardfork('spuriousDragon')
// EIP155 spec:
// If block.number >= 2,675,000 and v = CHAIN_ID * 2 + 35 or v = CHAIN_ID * 2 + 36, then when computing the hash of a transaction for purposes of signing or recovering, instead of hashing only the first six elements (i.e. nonce, gasprice, startgas, to, value, data), hash nine elements, with v replaced by CHAIN_ID, r = 0 and s = 0.
const v = this.v?.toNumber()
const vAndChainIdMeetEIP155Conditions =
v === this.getChainId() * 2 + 35 || v === this.getChainId() * 2 + 36
return vAndChainIdMeetEIP155Conditions && onEIP155BlockOrLater
}
private _getMessageToSign(withEIP155: boolean) {
const values = [
bnToRlp(this.nonce),
bnToRlp(this.gasPrice),
bnToRlp(this.gasLimit),
this.to !== undefined ? this.to.buf : Buffer.from([]),
bnToRlp(this.value),
this.data,
]
if (withEIP155) {
values.push(toBuffer(this.getChainId()))
values.push(unpadBuffer(toBuffer(0)))
values.push(unpadBuffer(toBuffer(0)))
}
return rlphash(values)
}
/**
* Validates tx's `v` value
*/
private _validateTxV(v: BN | undefined): void {
if (v === undefined || v.toNumber() === 0) {
return
}
if (!this.common.gteHardfork('spuriousDragon')) {
return
}
const vInt = v.toNumber()
if (vInt === 27 || vInt === 28) {
return
}
const isValidEIP155V =
vInt === this.getChainId() * 2 + 35 || vInt === this.getChainId() * 2 + 36
if (!isValidEIP155V) {
throw new Error(
`Incompatible EIP155-based V ${vInt} and chain id ${this.getChainId()}. See the Common parameter of the Transaction constructor to set the chain id.`
)
}
}
}