eth2.0-specs/specs/eip4844/light-client/full-node.md

2.9 KiB

EIP4844 Light Client -- Full Node

Notice: This document is a work-in-progress for researchers and implementers.

Table of contents

Introduction

This upgrade adds information about the execution payload to light client data as part of the EIP4844 upgrade.

Helper functions

Modified block_to_light_client_header

def block_to_light_client_header(block: SignedBeaconBlock) -> LightClientHeader:
    epoch = compute_epoch_at_slot(block.message.slot)

    if epoch >= CAPELLA_FORK_EPOCH:
        payload = block.message.body.execution_payload
        execution_header = ExecutionPayloadHeader(
            parent_hash=payload.parent_hash,
            fee_recipient=payload.fee_recipient,
            state_root=payload.state_root,
            receipts_root=payload.receipts_root,
            logs_bloom=payload.logs_bloom,
            prev_randao=payload.prev_randao,
            block_number=payload.block_number,
            gas_limit=payload.gas_limit,
            gas_used=payload.gas_used,
            timestamp=payload.timestamp,
            extra_data=payload.extra_data,
            base_fee_per_gas=payload.base_fee_per_gas,
            block_hash=payload.block_hash,
            transactions_root=hash_tree_root(payload.transactions),
            withdrawals_root=hash_tree_root(payload.withdrawals),
        )

        # [New in EIP4844]
        if epoch >= EIP4844_FORK_EPOCH:
            execution_header.excess_data_gas = payload.excess_data_gas

        execution_branch = compute_merkle_proof_for_block_body(block.message.body, EXECUTION_PAYLOAD_INDEX)
    else:
        # Note that during fork transitions, `finalized_header` may still point to earlier forks.
        # While Bellatrix blocks also contain an `ExecutionPayload` (minus `withdrawals_root`),
        # it was not included in the corresponding light client data. To ensure compatibility
        # with legacy data going through `upgrade_lc_header_to_capella`, leave out execution data.
        execution_header = ExecutionPayloadHeader()
        execution_branch = [Bytes32() for _ in range(floorlog2(EXECUTION_PAYLOAD_INDEX))]

    return LightClientHeader(
        beacon=BeaconBlockHeader(
            slot=block.message.slot,
            proposer_index=block.message.proposer_index,
            parent_root=block.message.parent_root,
            state_root=block.message.state_root,
            body_root=hash_tree_root(block.message.body),
        ),
        execution=execution_header,
        execution_branch=execution_branch,
    )