ethereum.forks.homestead.transactions

Transactions are atomic units of work created externally to Ethereum and submitted to be executed. If Ethereum is viewed as a state machine, transactions are the events that move between states.

Transaction

Atomic operation performed on the block chain.

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@slotted_freezable
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@dataclass
class Transaction:

nonce

A scalar value equal to the number of transactions sent by the sender.

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    nonce: U256

gas_price

The price of gas for this transaction, in wei.

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    gas_price: Uint

gas

The maximum amount of gas that can be used by this transaction.

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    gas: Uint

to

The address of the recipient. If empty, the transaction is a contract creation.

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    to: Bytes0 | Address

value

The amount of ether (in wei) to send with this transaction.

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    value: U256

data

The data payload of the transaction, which can be used to call functions on contracts or to create new contracts.

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    data: Bytes

v

The recovery id of the signature.

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    v: U256

r

The first part of the signature.

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    r: U256

s

The second part of the signature.

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    s: U256

validate_transaction

Verifies a transaction.

The gas in a transaction gets used to pay for the intrinsic cost of operations, therefore if there is insufficient gas then it would not be possible to execute a transaction and it will be declared invalid.

Additionally, the nonce of a transaction must not equal or exceed the limit defined in EIP-2681. In practice, defining the limit as 2**64-1 has no impact because sending 2**64-1 transactions is improbable. It's not strictly impossible though, 2**64-1 transactions is the entire capacity of the Ethereum blockchain at 2022 gas limits for a little over 22 years.

This function takes a transaction as a parameter and returns the intrinsic gas cost of the transaction after validation. It throws an InsufficientTransactionGasError exception if the transaction does not provide enough gas to cover the intrinsic cost, and a NonceOverflowError exception if the nonce is greater than 2**64 - 2.

def validate_transaction(​tx: Transaction​) -> Uint:
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    """
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    Verifies a transaction.
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    The gas in a transaction gets used to pay for the intrinsic cost of
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    operations, therefore if there is insufficient gas then it would not
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    be possible to execute a transaction and it will be declared invalid.
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    Additionally, the nonce of a transaction must not equal or exceed the
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    limit defined in [EIP-2681].
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    In practice, defining the limit as ``2**64-1`` has no impact because
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    sending ``2**64-1`` transactions is improbable. It's not strictly
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    impossible though, ``2**64-1`` transactions is the entire capacity of the
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    Ethereum blockchain at 2022 gas limits for a little over 22 years.
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    This function takes a transaction as a parameter and returns the intrinsic
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    gas cost of the transaction after validation. It throws an
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    `InsufficientTransactionGasError` exception if the transaction does not
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    provide enough gas to cover the intrinsic cost, and a `NonceOverflowError`
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    exception if the nonce is greater than `2**64 - 2`.
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    [EIP-2681]: https://eips.ethereum.org/EIPS/eip-2681
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    """
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    intrinsic_gas = calculate_intrinsic_cost(tx)
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    if intrinsic_gas > tx.gas:
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        raise InsufficientTransactionGasError("Insufficient gas")
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    if U256(tx.nonce) >= U256(U64.MAX_VALUE):
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        raise NonceOverflowError("Nonce too high")
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    return intrinsic_gas

calculate_intrinsic_cost

Calculates the gas that is charged before execution is started.

The intrinsic cost of the transaction is charged before execution has begun. Functions/operations in the EVM cost money to execute so this intrinsic cost is for the operations that need to be paid for as part of the transaction. Data transfer, for example, is part of this intrinsic cost. It costs ether to send data over the wire and that ether is accounted for in the intrinsic cost calculated in this function. This intrinsic cost must be calculated and paid for before execution in order for all operations to be implemented.

The intrinsic cost includes:

  1. Base cost (TX_BASE)

  2. Cost for data (zero and non-zero bytes)

  3. Cost for contract creation (if applicable)

This function takes a transaction as a parameter and returns the intrinsic gas cost of the transaction.

def calculate_intrinsic_cost(​tx: Transaction​) -> Uint:
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    """
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    Calculates the gas that is charged before execution is started.
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    The intrinsic cost of the transaction is charged before execution has
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    begun. Functions/operations in the EVM cost money to execute so this
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    intrinsic cost is for the operations that need to be paid for as part of
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    the transaction. Data transfer, for example, is part of this intrinsic
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    cost. It costs ether to send data over the wire and that ether is
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    accounted for in the intrinsic cost calculated in this function. This
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    intrinsic cost must be calculated and paid for before execution in order
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    for all operations to be implemented.
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    The intrinsic cost includes:
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    1. Base cost (`TX_BASE`)
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    2. Cost for data (zero and non-zero bytes)
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    3. Cost for contract creation (if applicable)
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    This function takes a transaction as a parameter and returns the intrinsic
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    gas cost of the transaction.
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    """
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    from .vm.gas import GasCosts
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    num_zeros = Uint(tx.data.count(0))
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    num_non_zeros = ulen(tx.data) - num_zeros
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    data_cost = (
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        num_zeros * GasCosts.TX_DATA_PER_ZERO
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        + num_non_zeros * GasCosts.TX_DATA_PER_NON_ZERO
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    )
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    if tx.to == Bytes0(b""):
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        create_cost = GasCosts.TX_CREATE
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    else:
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        create_cost = Uint(0)
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    return GasCosts.TX_BASE + data_cost + create_cost

recover_sender

Extracts the sender address from a transaction.

The v, r, and s values are the three parts that make up the signature of a transaction. In order to recover the sender of a transaction the two components needed are the signature (v, r, and s) and the signing hash of the transaction. The sender's public key can be obtained with these two values and therefore the sender address can be retrieved.

This function takes a transaction as a parameter and returns the address of the sender of the transaction. It raises an InvalidSignatureError if the signature values (r, s, v) are invalid.

def recover_sender(​tx: Transaction​) -> Address:
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    """
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    Extracts the sender address from a transaction.
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    The v, r, and s values are the three parts that make up the signature
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    of a transaction. In order to recover the sender of a transaction the two
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    components needed are the signature (``v``, ``r``, and ``s``) and the
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    signing hash of the transaction. The sender's public key can be obtained
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    with these two values and therefore the sender address can be retrieved.
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    This function takes a transaction as a parameter and returns
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    the address of the sender of the transaction. It raises an
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    `InvalidSignatureError` if the signature values (r, s, v) are invalid.
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    """
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    v, r, s = tx.v, tx.r, tx.s
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    if v != 27 and v != 28:
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        raise InvalidSignatureError("bad v")
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    if U256(0) >= r or r >= SECP256K1N:
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        raise InvalidSignatureError("bad r")
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    if U256(0) >= s or s > SECP256K1N // U256(2):
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        raise InvalidSignatureError("bad s")
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    public_key = secp256k1_recover(r, s, v - U256(27), signing_hash(tx))
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    return Address(keccak256(public_key)[12:32])

signing_hash

Compute the hash of a transaction used in the signature.

The values that are used to compute the signing hash set the rules for a transaction. For example, signing over the gas sets a limit for the amount of money that is allowed to be pulled out of the sender's account.

This function takes a transaction as a parameter and returns the signing hash of the transaction.

def signing_hash(​tx: Transaction​) -> Hash32:
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    """
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    Compute the hash of a transaction used in the signature.
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    The values that are used to compute the signing hash set the rules for a
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    transaction. For example, signing over the gas sets a limit for the
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    amount of money that is allowed to be pulled out of the sender's account.
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    This function takes a transaction as a parameter and returns the
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    signing hash of the transaction.
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    """
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    return keccak256(
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        rlp.encode(
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            (
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                tx.nonce,
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                tx.gas_price,
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                tx.gas,
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                tx.to,
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                tx.value,
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                tx.data,
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            )
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        )
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    )

get_transaction_hash

Compute the hash of a transaction.

This function takes a transaction as a parameter and returns the hash of the transaction.

def get_transaction_hash(​tx: Transaction​) -> Hash32:
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    """
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    Compute the hash of a transaction.
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    This function takes a transaction as a parameter and returns the
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    hash of the transaction.
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    """
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    return keccak256(rlp.encode(tx))