test_worst_returndatacopy()

Documentation for tests/benchmark/test_worst_memory.py::test_worst_returndatacopy@0f7c73a7.

Generate fixtures for these test cases for Prague with:

fill -v tests/benchmark/test_worst_memory.py::test_worst_returndatacopy --fork Prague

Test running a block filled with RETURNDATACOPY executions.

Source code in tests/benchmark/test_worst_memory.py

@pytest.mark.valid_from("Cancun")
@pytest.mark.parametrize(
    "size",
    [
        pytest.param(0, id="0 bytes"),
        pytest.param(100, id="100 bytes"),
        pytest.param(10 * 1024, id="10KiB"),
        pytest.param(1024 * 1024, id="1MiB"),
    ],
)
@pytest.mark.parametrize(
    "fixed_dst",
    [
        True,
        False,
    ],
)
def test_worst_returndatacopy(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
    size: int,
    fixed_dst: bool,
):
    """Test running a block filled with RETURNDATACOPY executions."""
    env = Environment()
    max_code_size = fork.max_code_size()

    # Create the contract that will RETURN the data that will be used for RETURNDATACOPY.
    # Random-ish data is injected at different points in memory to avoid making the content
    # predictable. If `size` is 0, this helper contract won't be used.
    code = (
        Op.MSTORE8(0, Op.GAS)
        + Op.MSTORE8(size // 2, Op.GAS)
        + Op.MSTORE8(size - 1, Op.GAS)
        + Op.RETURN(0, size)
    )
    helper_contract = pre.deploy_contract(code=code)

    # We create the contract that will be doing the RETURNDATACOPY multiple times.
    returndata_gen = Op.STATICCALL(address=helper_contract) if size > 0 else Bytecode()
    dst = 0 if fixed_dst else Op.MOD(Op.GAS, 7)
    attack_iter = Op.RETURNDATACOPY(dst, Op.PUSH0, Op.RETURNDATASIZE)

    jumpdest = Op.JUMPDEST
    jump_back = Op.JUMP(len(returndata_gen))
    # The attack loop is constructed as:
    # ```
    # JUMPDEST(#)
    # RETURNDATACOPY(...)
    # RETURNDATACOPY(...)
    # ...
    # STATICCALL(address=helper_contract)
    # JUMP(#)
    # ```
    # The goal is that once per (big) loop iteration, the helper contract is called to
    # generate fresh returndata to continue calling RETURNDATACOPY.
    max_iters_loop = (
        max_code_size - 2 * len(returndata_gen) - len(jumpdest) - len(jump_back)
    ) // len(attack_iter)
    code = (
        returndata_gen
        + jumpdest
        + sum([attack_iter] * max_iters_loop)
        + returndata_gen
        + jump_back
    )
    assert len(code) <= max_code_size, (
        f"Code size {len(code)} is not equal to max code size {max_code_size}."
    )

    tx = Transaction(
        to=pre.deploy_contract(code=code),
        gas_limit=env.gas_limit,
        sender=pre.fund_eoa(),
    )

    state_test(
        genesis_environment=env,
        pre=pre,
        post={},
        tx=tx,
    )

Parametrized Test Cases

The interactive table below is also available as a standalone page.

Fork All Forks Cancun Prague Osaka

Fixture Type All Fixture Types state_test blockchain_test

Test ID (Abbreviated)	fixed_dst	size
...fork_Cancun-state_test-fixed_dst_True-0 bytes	True	0
...fork_Cancun-state_test-fixed_dst_True-100 bytes	True	100
...fork_Cancun-state_test-fixed_dst_True-10KiB	True	10240
...fork_Cancun-state_test-fixed_dst_True-1MiB	True	1048576
...fork_Cancun-state_test-fixed_dst_False-0 bytes	False	0
...fork_Cancun-state_test-fixed_dst_False-100 bytes	False	100
...fork_Cancun-state_test-fixed_dst_False-10KiB	False	10240
...fork_Cancun-state_test-fixed_dst_False-1MiB	False	1048576
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_True-0 bytes	True	0
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_True-100 bytes	True	100
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_True-10KiB	True	10240
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_True-1MiB	True	1048576
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_False-0 bytes	False	0
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_False-100 bytes	False	100
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_False-10KiB	False	10240
...fork_Cancun-blockchain_test_from_state_test-fixed_dst_False-1MiB	False	1048576
...fork_Prague-state_test-fixed_dst_True-0 bytes	True	0
...fork_Prague-state_test-fixed_dst_True-100 bytes	True	100
...fork_Prague-state_test-fixed_dst_True-10KiB	True	10240
...fork_Prague-state_test-fixed_dst_True-1MiB	True	1048576
...fork_Prague-state_test-fixed_dst_False-0 bytes	False	0
...fork_Prague-state_test-fixed_dst_False-100 bytes	False	100
...fork_Prague-state_test-fixed_dst_False-10KiB	False	10240
...fork_Prague-state_test-fixed_dst_False-1MiB	False	1048576
...fork_Prague-blockchain_test_from_state_test-fixed_dst_True-0 bytes	True	0
...fork_Prague-blockchain_test_from_state_test-fixed_dst_True-100 bytes	True	100
...fork_Prague-blockchain_test_from_state_test-fixed_dst_True-10KiB	True	10240
...fork_Prague-blockchain_test_from_state_test-fixed_dst_True-1MiB	True	1048576
...fork_Prague-blockchain_test_from_state_test-fixed_dst_False-0 bytes	False	0
...fork_Prague-blockchain_test_from_state_test-fixed_dst_False-100 bytes	False	100
...fork_Prague-blockchain_test_from_state_test-fixed_dst_False-10KiB	False	10240
...fork_Prague-blockchain_test_from_state_test-fixed_dst_False-1MiB	False	1048576
...fork_Osaka-state_test-fixed_dst_True-0 bytes	True	0
...fork_Osaka-state_test-fixed_dst_True-100 bytes	True	100
...fork_Osaka-state_test-fixed_dst_True-10KiB	True	10240
...fork_Osaka-state_test-fixed_dst_True-1MiB	True	1048576
...fork_Osaka-state_test-fixed_dst_False-0 bytes	False	0
...fork_Osaka-state_test-fixed_dst_False-100 bytes	False	100
...fork_Osaka-state_test-fixed_dst_False-10KiB	False	10240
...fork_Osaka-state_test-fixed_dst_False-1MiB	False	1048576
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_True-0 bytes	True	0
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_True-100 bytes	True	100
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_True-10KiB	True	10240
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_True-1MiB	True	1048576
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_False-0 bytes	False	0
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_False-100 bytes	False	100
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_False-10KiB	False	10240
...fork_Osaka-blockchain_test_from_state_test-fixed_dst_False-1MiB	False	1048576