ethereum.forks.prague.vm.eoa_delegation

Set EOA account code.

SET_CODE_TX_MAGIC

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SET_CODE_TX_MAGIC = b"\x05"

EOA_DELEGATION_MARKER

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EOA_DELEGATION_MARKER = b"\xef\x01\x00"

EOA_DELEGATION_MARKER_LENGTH

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EOA_DELEGATION_MARKER_LENGTH = len(EOA_DELEGATION_MARKER)

EOA_DELEGATED_CODE_LENGTH

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EOA_DELEGATED_CODE_LENGTH = 23

NULL_ADDRESS

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NULL_ADDRESS = hex_to_address("0x0000000000000000000000000000000000000000")

is_valid_delegation

Whether the code is a valid delegation designation.

Parameters

code: bytes The code to check.

Returns

valid : bool True if the code is a valid delegation designation, False otherwise.

def is_valid_delegation(​code: bytes​) -> bool:
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    <snip>
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    return (
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        len(code) == EOA_DELEGATED_CODE_LENGTH
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        and code[:EOA_DELEGATION_MARKER_LENGTH] == EOA_DELEGATION_MARKER
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    )

get_delegated_code_address

Get the address to which the code delegates.

Parameters

code: bytes The code to get the address from.

Returns

address : Optional[Address] The address of the delegated code.

def get_delegated_code_address(​code: bytes​) -> Optional[Address]:
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    <snip>
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    if is_valid_delegation(code):
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        return Address(code[EOA_DELEGATION_MARKER_LENGTH:])
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    return None

recover_authority

Recover the authority address from the authorization.

Parameters

authorization The authorization to recover the authority from.

Raises

InvalidSignatureError If the signature is invalid.

Returns

authority : Address The recovered authority address.

def recover_authority(​authorization: Authorization​) -> Address:
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    <snip>
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    y_parity, r, s = authorization.y_parity, authorization.r, authorization.s
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    if y_parity not in (0, 1):
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        raise InvalidSignatureError("Invalid y_parity in authorization")
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    if U256(0) >= r or r >= SECP256K1N:
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        raise InvalidSignatureError("Invalid r value in authorization")
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    if U256(0) >= s or s > SECP256K1N // U256(2):
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        raise InvalidSignatureError("Invalid s value in authorization")
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    signing_hash = keccak256(
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        SET_CODE_TX_MAGIC
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        + rlp.encode(
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            (
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                authorization.chain_id,
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                authorization.address,
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                authorization.nonce,
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            )
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        )
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    )
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    public_key = secp256k1_recover(r, s, U256(y_parity), signing_hash)
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    return Address(keccak256(public_key)[12:32])

access_delegation

Get the delegation address, code, and the cost of access from the address.

Parameters

evm : Evm The execution frame. address : Address The address to get the delegation from.

Returns

delegation : Tuple[bool, Address, Bytes, Uint] The delegation address, code, and access gas cost.

def access_delegation(​evm: Evm, ​​address: Address​) -> Tuple[bool, Address, Bytes, Uint]:
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    <snip>
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    tx_state = evm.message.tx_env.state
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    code = get_code(tx_state, get_account(tx_state, address).code_hash)
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    if not is_valid_delegation(code):
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        return False, address, code, Uint(0)
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    address = Address(code[EOA_DELEGATION_MARKER_LENGTH:])
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    if address in evm.accessed_addresses:
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        access_gas_cost = GasCosts.WARM_ACCESS
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    else:
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        evm.accessed_addresses.add(address)
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        access_gas_cost = GasCosts.COLD_ACCOUNT_ACCESS
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    code = get_code(tx_state, get_account(tx_state, address).code_hash)
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    return True, address, code, access_gas_cost

validate_authorization

Check if the given Authorization is valid against the current state.

Returns the authority address or None if the validation was unsuccessful.

def validate_authorization(​message: Message, ​​auth: Authorization​) -> None | Address:
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    <snip>
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    tx_state = message.tx_env.state
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    if auth.chain_id not in (message.block_env.chain_id, U256(0)):
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        return None
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    if auth.nonce >= U64.MAX_VALUE:
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        return None
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    try:
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        authority = recover_authority(auth)
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    except InvalidSignatureError:
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        return None
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    message.accessed_addresses.add(authority)
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    authority_account = get_account(tx_state, authority)
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    authority_code = get_code(tx_state, authority_account.code_hash)
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    if authority_code and not is_valid_delegation(authority_code):
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        return None
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    authority_nonce = authority_account.nonce
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    if authority_nonce != auth.nonce:
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        return None
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    return authority

set_delegation

Set the delegation code for the authorities in the message.

Parameters

message : Transaction specific items.

Returns

refund_counter: U256 Refund from authority which already exists in state.

def set_delegation(​message: Message​) -> U256:
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    <snip>
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    tx_state = message.tx_env.state
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    refund_counter = U256(0)
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    for auth in message.tx_env.authorizations:
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        match validate_authorization(message, auth):
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            case None:
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                continue
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            case authority:
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                pass
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        if account_exists(tx_state, authority):
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            refund_counter += U256(
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                GasCosts.AUTH_PER_EMPTY_ACCOUNT
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                - GasCosts.REFUND_AUTH_PER_EXISTING_ACCOUNT
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            )
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        if auth.address == NULL_ADDRESS:
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            code_to_set = b""
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        else:
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            code_to_set = EOA_DELEGATION_MARKER + auth.address
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        set_code(tx_state, authority, code_to_set)
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        increment_nonce(tx_state, authority)
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    if message.code_address is None:
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        raise InvalidBlock("Invalid type 4 transaction: no target")
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    message.code = get_code(
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        tx_state, get_account(tx_state, message.code_address).code_hash
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    )
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    return refund_counter