Ethereum Specification
Table of Contents
Introduction
Entry point for the Ethereum specification.
Module Contents
Classes
History and current state of the block chain. |
Functions
Transforms the state from the previous hard fork (old) into the block |
|
Obtain the list of hashes of the previous 256 blocks in order of |
|
Attempts to apply a block to an existing block chain. |
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Calculates the base fee per gas for the block. |
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Verifies a block header. |
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Check if the transaction is includable in the block. |
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Make the receipt for a transaction that was executed. |
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Executes a block. |
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Execute a transaction against the provided environment. |
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Verifies a transaction. |
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Calculates the gas that is charged before execution is started. |
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Extracts the sender address from a transaction. |
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Compute the hash of a transaction used in a legacy (pre EIP 155) signature. |
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Compute the hash of a transaction used in a EIP 155 signature. |
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Compute the hash of a transaction used in a EIP 2930 signature. |
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Compute the hash of a transaction used in a EIP 1559 signature. |
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Computes the hash of a block header. |
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Validates the gas limit for a block. |
Attributes
Module Details
BASE_FEE_MAX_CHANGE_DENOMINATOR
- BASE_FEE_MAX_CHANGE_DENOMINATOR
BASE_FEE_MAX_CHANGE_DENOMINATOR = 8
ELASTICITY_MULTIPLIER
- ELASTICITY_MULTIPLIER
ELASTICITY_MULTIPLIER = 2
GAS_LIMIT_ADJUSTMENT_FACTOR
- GAS_LIMIT_ADJUSTMENT_FACTOR
GAS_LIMIT_ADJUSTMENT_FACTOR = 1024
GAS_LIMIT_MINIMUM
- GAS_LIMIT_MINIMUM
GAS_LIMIT_MINIMUM = 5000
EMPTY_OMMER_HASH
- EMPTY_OMMER_HASH
EMPTY_OMMER_HASH = keccak256(rlp.encode([]))
BlockChain
History and current state of the block chain.
apply_fork
- apply_fork(old)
Transforms the state from the previous hard fork (old) into the block chain object for this hard fork and returns it.
When forks need to implement an irregular state transition, this function is used to handle the irregularity. See the DAO Fork for an example.
- Parameters
old – Previous block chain object.
- Returns
new – Upgraded block chain object for this hard fork.
- Return type
BlockChain
def apply_fork(old: BlockChain) -> BlockChain:
return old
get_last_256_block_hashes
- get_last_256_block_hashes(chain)
Obtain the list of hashes of the previous 256 blocks in order of increasing block number.
This function will return less hashes for the first 256 blocks.
The
BLOCKHASHopcode needs to access the latest hashes on the chain, therefore this function retrieves them.- Parameters
chain – History and current state.
- Returns
recent_block_hashes – Hashes of the recent 256 blocks in order of increasing block number.
- Return type
List[Hash32]
def get_last_256_block_hashes(chain: BlockChain) -> List[Hash32]:
recent_blocks = chain.blocks[-255:]
# TODO: This function has not been tested rigorously
if len(recent_blocks) == 0:
return []
recent_block_hashes = []
for block in recent_blocks:
prev_block_hash = block.header.parent_hash
recent_block_hashes.append(prev_block_hash)
# We are computing the hash only for the most recent block and not for
# the rest of the blocks as they have successors which have the hash of
# the current block as parent hash.
most_recent_block_hash = keccak256(rlp.encode(recent_blocks[-1].header))
recent_block_hashes.append(most_recent_block_hash)
return recent_block_hashes
state_transition
- state_transition(chain, block)
Attempts to apply a block to an existing block chain.
All parts of the block’s contents need to be verified before being added to the chain. Blocks are verified by ensuring that the contents of the block make logical sense with the contents of the parent block. The information in the block’s header must also match the corresponding information in the block.
To implement Ethereum, in theory clients are only required to store the most recent 255 blocks of the chain since as far as execution is concerned, only those blocks are accessed. Practically, however, clients should store more blocks to handle reorgs.
- Parameters
chain – History and current state.
block – Block to apply to chain.
def state_transition(chain: BlockChain, block: Block) -> None:
parent_header = chain.blocks[-1].header
validate_header(block.header, parent_header)
ensure(block.ommers == (), InvalidBlock)
(
gas_used,
transactions_root,
receipt_root,
block_logs_bloom,
state,
withdrawals_root,
) = apply_body(
chain.state,
get_last_256_block_hashes(chain),
block.header.coinbase,
block.header.number,
block.header.base_fee_per_gas,
block.header.gas_limit,
block.header.timestamp,
block.header.prev_randao,
block.transactions,
chain.chain_id,
block.withdrawals,
)
ensure(gas_used == block.header.gas_used, InvalidBlock)
ensure(transactions_root == block.header.transactions_root, InvalidBlock)
ensure(state_root(state) == block.header.state_root, InvalidBlock)
ensure(receipt_root == block.header.receipt_root, InvalidBlock)
ensure(block_logs_bloom == block.header.bloom, InvalidBlock)
ensure(withdrawals_root == block.header.withdrawals_root, InvalidBlock)
chain.blocks.append(block)
if len(chain.blocks) > 255:
# Real clients have to store more blocks to deal with reorgs, but the
# protocol only requires the last 255
chain.blocks = chain.blocks[-255:]
calculate_base_fee_per_gas
- calculate_base_fee_per_gas(block_gas_limit, parent_gas_limit, parent_gas_used, parent_base_fee_per_gas)
Calculates the base fee per gas for the block.
- Parameters
block_gas_limit – Gas limit of the block for which the base fee is being calculated.
parent_gas_limit – Gas limit of the parent block.
parent_gas_used – Gas used in the parent block.
parent_base_fee_per_gas – Base fee per gas of the parent block.
- Returns
base_fee_per_gas – Base fee per gas for the block.
- Return type
Uint
def calculate_base_fee_per_gas(
block_gas_limit: Uint,
parent_gas_limit: Uint,
parent_gas_used: Uint,
parent_base_fee_per_gas: Uint,
) -> Uint:
parent_gas_target = parent_gas_limit // ELASTICITY_MULTIPLIER
ensure(
check_gas_limit(block_gas_limit, parent_gas_limit),
InvalidBlock,
)
if parent_gas_used == parent_gas_target:
expected_base_fee_per_gas = parent_base_fee_per_gas
elif parent_gas_used > parent_gas_target:
gas_used_delta = parent_gas_used - parent_gas_target
parent_fee_gas_delta = parent_base_fee_per_gas * gas_used_delta
target_fee_gas_delta = parent_fee_gas_delta // parent_gas_target
base_fee_per_gas_delta = max(
target_fee_gas_delta // BASE_FEE_MAX_CHANGE_DENOMINATOR,
1,
)
expected_base_fee_per_gas = (
parent_base_fee_per_gas + base_fee_per_gas_delta
)
else:
gas_used_delta = parent_gas_target - parent_gas_used
parent_fee_gas_delta = parent_base_fee_per_gas * gas_used_delta
target_fee_gas_delta = parent_fee_gas_delta // parent_gas_target
base_fee_per_gas_delta = (
target_fee_gas_delta // BASE_FEE_MAX_CHANGE_DENOMINATOR
)
expected_base_fee_per_gas = (
parent_base_fee_per_gas - base_fee_per_gas_delta
)
return Uint(expected_base_fee_per_gas)
validate_header
- validate_header(header, parent_header)
Verifies a block header.
In order to consider a block’s header valid, the logic for the quantities in the header should match the logic for the block itself. For example the header timestamp should be greater than the block’s parent timestamp because the block was created after the parent block. Additionally, the block’s number should be directly folowing the parent block’s number since it is the next block in the sequence.
- Parameters
header – Header to check for correctness.
parent_header – Parent Header of the header to check for correctness
def validate_header(header: Header, parent_header: Header) -> None:
ensure(header.gas_used <= header.gas_limit, InvalidBlock)
expected_base_fee_per_gas = calculate_base_fee_per_gas(
header.gas_limit,
parent_header.gas_limit,
parent_header.gas_used,
parent_header.base_fee_per_gas,
)
ensure(expected_base_fee_per_gas == header.base_fee_per_gas, InvalidBlock)
ensure(header.timestamp > parent_header.timestamp, InvalidBlock)
ensure(header.number == parent_header.number + 1, InvalidBlock)
ensure(len(header.extra_data) <= 32, InvalidBlock)
ensure(header.difficulty == 0, InvalidBlock)
ensure(header.nonce == b"\x00\x00\x00\x00\x00\x00\x00\x00", InvalidBlock)
ensure(header.ommers_hash == EMPTY_OMMER_HASH, InvalidBlock)
block_parent_hash = keccak256(rlp.encode(parent_header))
ensure(header.parent_hash == block_parent_hash, InvalidBlock)
check_transaction
- check_transaction(tx, base_fee_per_gas, gas_available, chain_id)
Check if the transaction is includable in the block.
- Parameters
tx – The transaction.
base_fee_per_gas – The block base fee.
gas_available – The gas remaining in the block.
chain_id – The ID of the current chain.
- Returns
sender_address – The sender of the transaction.
effective_gas_price – The price to charge for gas when the transaction is executed.
- Raises
InvalidBlock : – If the transaction is not includable.
def check_transaction(
tx: Transaction,
base_fee_per_gas: Uint,
gas_available: Uint,
chain_id: U64,
) -> Tuple[Address, Uint]:
ensure(tx.gas <= gas_available, InvalidBlock)
sender_address = recover_sender(chain_id, tx)
if isinstance(tx, FeeMarketTransaction):
ensure(tx.max_fee_per_gas >= tx.max_priority_fee_per_gas, InvalidBlock)
ensure(tx.max_fee_per_gas >= base_fee_per_gas, InvalidBlock)
priority_fee_per_gas = min(
tx.max_priority_fee_per_gas,
tx.max_fee_per_gas - base_fee_per_gas,
)
effective_gas_price = priority_fee_per_gas + base_fee_per_gas
else:
ensure(tx.gas_price >= base_fee_per_gas, InvalidBlock)
effective_gas_price = tx.gas_price
return sender_address, effective_gas_price
make_receipt
- make_receipt(tx, error, cumulative_gas_used, logs)
Make the receipt for a transaction that was executed.
- Parameters
tx – The executed transaction.
error – The error fromError in the executiontop level frame of the transaction, if any.
cumulative_gas_used – The total gas used so far in the block after the transaction was executed.
logs – The logs produced by the transaction.
- Returns
The receipt for the transaction.
- Return type
receipt
def make_receipt(
tx: Transaction,
error: Optional[Exception],
cumulative_gas_used: Uint,
logs: Tuple[Log, ...],
) -> Union[Bytes, Receipt]:
receipt = Receipt(
succeeded=error is None,
cumulative_gas_used=cumulative_gas_used,
bloom=logs_bloom(logs),
logs=logs,
)
if isinstance(tx, AccessListTransaction):
return b"\x01" + rlp.encode(receipt)
if isinstance(tx, FeeMarketTransaction):
return b"\x02" + rlp.encode(receipt)
else:
return receipt
apply_body
- apply_body(state, block_hashes, coinbase, block_number, base_fee_per_gas, block_gas_limit, block_time, prev_randao, transactions, chain_id, withdrawals)
Executes a block.
Many of the contents of a block are stored in data structures called tries. There is a transactions trie which is similar to a ledger of the transactions stored in the current block. There is also a receipts trie which stores the results of executing a transaction, like the post state and gas used. This function creates and executes the block that is to be added to the chain.
- Parameters
state – Current account state.
block_hashes – List of hashes of the previous 256 blocks in the order of increasing block number.
coinbase – Address of account which receives block reward and transaction fees.
block_number – Position of the block within the chain.
base_fee_per_gas – Base fee per gas of within the block.
block_gas_limit – Initial amount of gas available for execution in this block.
block_time – Time the block was produced, measured in seconds since the epoch.
prev_randao – The previous randao from the beacon chain.
transactions – Transactions included in the block.
ommers – Headers of ancestor blocks which are not direct parents (formerly uncles.)
chain_id – ID of the executing chain.
withdrawals – Withdrawals to be processed in the current block.
- Returns
gas_available (ethereum.base_types.Uint) – Remaining gas after all transactions have been executed.
transactions_root (ethereum.fork_types.Root) – Trie root of all the transactions in the block.
receipt_root (ethereum.fork_types.Root) – Trie root of all the receipts in the block.
block_logs_bloom (Bloom) – Logs bloom of all the logs included in all the transactions of the block.
state (ethereum.fork_types.State) – State after all transactions have been executed.
def apply_body(
state: State,
block_hashes: List[Hash32],
coinbase: Address,
block_number: Uint,
base_fee_per_gas: Uint,
block_gas_limit: Uint,
block_time: U256,
prev_randao: Bytes32,
transactions: Tuple[Union[LegacyTransaction, Bytes], ...],
chain_id: U64,
withdrawals: Tuple[Withdrawal, ...],
) -> Tuple[Uint, Root, Root, Bloom, State]:State, Root]:
gas_available = block_gas_limit
transactions_trie: Trie[
Bytes, Optional[Union[Bytes, LegacyTransaction]]
] = Trie(secured=False, default=None)
receipts_trie: Trie[Bytes, Optional[Union[Bytes, Receipt]]] = Trie(
secured=False, default=None
)
withdrawals_trie: Trie[Bytes, Optional[Union[Bytes, Withdrawal]]] = Trie(
secured=False, default=None
)
block_logs: Tuple[Log, ...] = ()
for i, tx in enumerate(map(decode_transaction, transactions)):
trie_set(
transactions_trie, rlp.encode(Uint(i)), encode_transaction(tx)
)
sender_address, effective_gas_price = check_transaction(
tx, base_fee_per_gas, gas_available, chain_id
)
env = vm.Environment(
caller=sender_address,
origin=sender_address,
block_hashes=block_hashes,
coinbase=coinbase,
number=block_number,
gas_limit=block_gas_limit,
base_fee_per_gas=base_fee_per_gas,
gas_price=effective_gas_price,
time=block_time,
prev_randao=prev_randao,
state=state,
chain_id=chain_id,
traces=[],
)
gas_used, logs, error = process_transaction(env, tx)
gas_available -= gas_used
receipt = make_receipt(
tx, error, (block_gas_limit - gas_available), logs
)
trie_set(
receipts_trie,
rlp.encode(Uint(i)),
receipt,
)
block_logs += logs
block_gas_used = block_gas_limit - gas_available
block_logs_bloom = logs_bloom(block_logs)
for i, wd in enumerate(withdrawals):
trie_set(withdrawals_trie, rlp.encode(Uint(i)), rlp.encode(wd))
process_withdrawal(state, wd)
if account_exists_and_is_empty(state, wd.address):
destroy_account(state, wd.address)
return (
block_gas_used,
root(transactions_trie),
root(receipts_trie),
block_logs_bloom,
state,
root(withdrawals_trie),
)
process_transaction
- process_transaction(env, tx)
Execute a transaction against the provided environment.
This function processes the actions needed to execute a transaction. It decrements the sender’s account after calculating the gas fee and refunds them the proper amount after execution. Calling contracts, deploying code, and incrementing nonces are all examples of actions that happen within this function or from a call made within this function.
Accounts that are marked for deletion are processed and destroyed after execution.
- Parameters
env – Environment for the Ethereum Virtual Machine.
tx – Transaction to execute.
- Returns
gas_left (ethereum.base_types.U256) – Remaining gas after execution.
logs (Tuple[ethereum.fork_types.Log, …]) – Logs generated during execution.
def process_transaction(
env: vm.Environment, tx: Transaction
) -> Tuple[Uint, Tuple[Log, ...], Optional[Exception]]:
ensure(validate_transaction(tx), InvalidBlock)
sender = env.origin
sender_account = get_account(env.state, sender)
if isinstance(tx, FeeMarketTransaction):
gas_fee = tx.gas * tx.max_fee_per_gas
else:
gas_fee = tx.gas * tx.gas_price
ensure(sender_account.nonce == tx.nonce, InvalidBlock)
ensure(sender_account.balance >= gas_fee + tx.value, InvalidBlock)
ensure(sender_account.code == bytearray(), InvalidBlock)
effective_gas_fee = tx.gas * env.gas_price
gas = tx.gas - calculate_intrinsic_cost(tx)
increment_nonce(env.state, sender)
sender_balance_after_gas_fee = sender_account.balance - effective_gas_fee
set_account_balance(env.state, sender, sender_balance_after_gas_fee)
preaccessed_addresses = set()
preaccessed_storage_keys = set()
preaccessed_addresses.add(env.coinbase)
if isinstance(tx, (AccessListTransaction, FeeMarketTransaction)):
for (address, keys) in tx.access_list:
preaccessed_addresses.add(address)
for key in keys:
preaccessed_storage_keys.add((address, key))
message = prepare_message(
sender,
tx.to,
tx.value,
tx.data,
gas,
env,
preaccessed_addresses=frozenset(preaccessed_addresses),
preaccessed_storage_keys=frozenset(preaccessed_storage_keys),
)
output = process_message_call(message, env)
gas_used = tx.gas - output.gas_left
gas_refund = min(gas_used // 5, output.refund_counter)
gas_refund_amount = (output.gas_left + gas_refund) * env.gas_price
# For non-1559 transactions env.gas_price == tx.gas_price
priority_fee_per_gas = env.gas_price - env.base_fee_per_gas
transaction_fee = (
tx.gas - output.gas_left - gas_refund
) * priority_fee_per_gas
total_gas_used = gas_used - gas_refund
# refund gas
sender_balance_after_refund = (
get_account(env.state, sender).balance + gas_refund_amount
)
set_account_balance(env.state, sender, sender_balance_after_refund)
# transfer miner fees
coinbase_balance_after_mining_fee = (
get_account(env.state, env.coinbase).balance + transaction_fee
)
if coinbase_balance_after_mining_fee != 0:
set_account_balance(
env.state, env.coinbase, coinbase_balance_after_mining_fee
)
elif account_exists_and_is_empty(env.state, env.coinbase):
destroy_account(env.state, env.coinbase)
for address in output.accounts_to_delete:
destroy_account(env.state, address)
for address in output.touched_accounts:
if account_exists_and_is_empty(env.state, address):
destroy_account(env.state, address)
return total_gas_used, output.logs, output.error
validate_transaction
- validate_transaction(tx)
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**64-1has no impact because sending2**64-1transactions is improbable. It’s not strictly impossible though,2**64-1transactions is the entire capacity of the Ethereum blockchain at 2022 gas limits for a little over 22 years.- Parameters
tx – Transaction to validate.
- Returns
verified – True if the transaction can be executed, or False otherwise.
- Return type
bool
def validate_transaction(tx: Transaction) -> bool:
if calculate_intrinsic_cost(tx) > tx.gas:
return calculate_intrinsic_cost(tx) <= tx.gasFalse
if tx.nonce >= 2**64 - 1:
return False
if tx.to == Bytes0(b"") and tx.nonce < 2**64 - 1len(tx.data) > 2 * MAX_CODE_SIZE:
return False
return True
calculate_intrinsic_cost
- calculate_intrinsic_cost(tx)
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.
- Parameters
tx – Transaction to compute the intrinsic cost of.
- Returns
verified – The intrinsic cost of the transaction.
- Return type
ethereum.base_types.Uint
def calculate_intrinsic_cost(tx: Transaction) -> Uint:
data_cost = 0
for byte in tx.data:
if byte == 0:
data_cost += TX_DATA_COST_PER_ZERO
else:
data_cost += TX_DATA_COST_PER_NON_ZERO
if tx.to == Bytes0(b""):
create_cost = TX_CREATE_COST
+ int(init_code_cost(Uint(len(tx.data))))
else:
create_cost = 0
access_list_cost = 0
if isinstance(tx, (AccessListTransaction, FeeMarketTransaction)):
for (_address, keys) in tx.access_list:
access_list_cost += TX_ACCESS_LIST_ADDRESS_COST
access_list_cost += len(keys) * TX_ACCESS_LIST_STORAGE_KEY_COST
return Uint(TX_BASE_COST + data_cost + create_cost + access_list_cost)
recover_sender
- recover_sender(chain_id, tx)
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, ands) 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.- Parameters
tx – Transaction of interest.
chain_id – ID of the executing chain.
- Returns
sender – The address of the account that signed the transaction.
- Return type
ethereum.fork_types.Address
def recover_sender(chain_id: U64, tx: Transaction) -> Address:
r, s = tx.r, tx.s
ensure(0 < r and r < SECP256K1N, InvalidBlock)
ensure(0 < s and s <= SECP256K1N // 2, InvalidBlock)
if isinstance(tx, LegacyTransaction):
v = tx.v
if v == 27 or v == 28:
public_key = secp256k1_recover(
r, s, v - 27, signing_hash_pre155(tx)
)
else:
ensure(
v == 35 + chain_id * 2 or v == 36 + chain_id * 2, InvalidBlock
)
public_key = secp256k1_recover(
r, s, v - 35 - chain_id * 2, signing_hash_155(tx, chain_id)
)
elif isinstance(tx, AccessListTransaction):
public_key = secp256k1_recover(
r, s, tx.y_parity, signing_hash_2930(tx)
)
elif isinstance(tx, FeeMarketTransaction):
public_key = secp256k1_recover(
r, s, tx.y_parity, signing_hash_1559(tx)
)
return Address(keccak256(public_key)[12:32])
signing_hash_pre155
- signing_hash_pre155(tx)
Compute the hash of a transaction used in a legacy (pre EIP 155) signature.
- Parameters
tx – Transaction of interest.
- Returns
hash – Hash of the transaction.
- Return type
ethereum.crypto.hash.Hash32
def signing_hash_pre155(tx: LegacyTransaction) -> Hash32:
return keccak256(
rlp.encode(
(
tx.nonce,
tx.gas_price,
tx.gas,
tx.to,
tx.value,
tx.data,
)
)
)
signing_hash_155
- signing_hash_155(tx, chain_id)
Compute the hash of a transaction used in a EIP 155 signature.
- Parameters
tx – Transaction of interest.
chain_id – The id of the current chain.
- Returns
hash – Hash of the transaction.
- Return type
ethereum.crypto.hash.Hash32
def signing_hash_155(tx: LegacyTransaction, chain_id: U64) -> Hash32:
return keccak256(
rlp.encode(
(
tx.nonce,
tx.gas_price,
tx.gas,
tx.to,
tx.value,
tx.data,
chain_id,
Uint(0),
Uint(0),
)
)
)
signing_hash_2930
- signing_hash_2930(tx)
Compute the hash of a transaction used in a EIP 2930 signature.
- Parameters
tx – Transaction of interest.
- Returns
hash – Hash of the transaction.
- Return type
ethereum.crypto.hash.Hash32
def signing_hash_2930(tx: AccessListTransaction) -> Hash32:
return keccak256(
b"\x01"
+ rlp.encode(
(
tx.chain_id,
tx.nonce,
tx.gas_price,
tx.gas,
tx.to,
tx.value,
tx.data,
tx.access_list,
)
)
)
signing_hash_1559
- signing_hash_1559(tx)
Compute the hash of a transaction used in a EIP 1559 signature.
- Parameters
tx – Transaction of interest.
- Returns
hash – Hash of the transaction.
- Return type
ethereum.crypto.hash.Hash32
def signing_hash_1559(tx: FeeMarketTransaction) -> Hash32:
return keccak256(
b"\x02"
+ rlp.encode(
(
tx.chain_id,
tx.nonce,
tx.max_priority_fee_per_gas,
tx.max_fee_per_gas,
tx.gas,
tx.to,
tx.value,
tx.data,
tx.access_list,
)
)
)
compute_header_hash
- compute_header_hash(header)
Computes the hash of a block header.
The header hash of a block is the canonical hash that is used to refer to a specific block and completely distinguishes a block from another.
keccak256is a function that produces a 256 bit hash of any input. It also takes in any number of bytes as an input and produces a single hash for them. A hash is a completely unique output for a single input. So an input corresponds to one unique hash that can be used to identify the input exactly.Prior to using the
keccak256hash function, the header must be encoded using the Recursive-Length Prefix. See Recursive Length Prefix (RLP) Encoding. RLP encoding the header converts it into a space-efficient format that allows for easy transfer of data between nodes. The purpose of RLP is to encode arbitrarily nested arrays of binary data, and RLP is the primary encoding method used to serialize objects in Ethereum’s execution layer. The only purpose of RLP is to encode structure; encoding specific data types (e.g. strings, floats) is left up to higher-order protocols.- Parameters
header – Header of interest.
- Returns
hash – Hash of the header.
- Return type
ethereum.crypto.hash.Hash32
def compute_header_hash(header: Header) -> Hash32:
return keccak256(rlp.encode(header))
check_gas_limit
- check_gas_limit(gas_limit, parent_gas_limit)
Validates the gas limit for a block.
The bounds of the gas limit,
max_adjustment_delta, is set as the quotient of the parent block’s gas limit and theGAS_LIMIT_ADJUSTMENT_FACTOR. Therefore, if the gas limit that is passed through as a parameter is greater than or equal to the sum of the parent’s gas and the adjustment delta then the limit for gas is too high and fails this function’s check. Similarly, if the limit is less than or equal to the difference of the parent’s gas and the adjustment delta or the predefinedGAS_LIMIT_MINIMUMthen this function’s check fails because the gas limit doesn’t allow for a sufficient or reasonable amount of gas to be used on a block.- Parameters
gas_limit – Gas limit to validate.
parent_gas_limit – Gas limit of the parent block.
- Returns
check – True if gas limit constraints are satisfied, False otherwise.
- Return type
bool
def check_gas_limit(gas_limit: Uint, parent_gas_limit: Uint) -> bool:
max_adjustment_delta = parent_gas_limit // GAS_LIMIT_ADJUSTMENT_FACTOR
if gas_limit >= parent_gas_limit + max_adjustment_delta:
return False
if gas_limit <= parent_gas_limit - max_adjustment_delta:
return False
if gas_limit < GAS_LIMIT_MINIMUM:
return False
return True