104 lines
4.2 KiB
Markdown
104 lines
4.2 KiB
Markdown
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# EIP-4788 -- Honest Validator
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**Notice**: This document is a work-in-progress for researchers and implementers.
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## Table of contents
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<!-- TOC -->
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Introduction](#introduction)
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- [Prerequisites](#prerequisites)
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- [Helpers](#helpers)
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- [Protocols](#protocols)
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- [`ExecutionEngine`](#executionengine)
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- [`get_payload`](#get_payload)
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- [Beacon chain responsibilities](#beacon-chain-responsibilities)
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- [Block proposal](#block-proposal)
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- [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
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- [ExecutionPayload](#executionpayload)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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<!-- /TOC -->
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## Introduction
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This document represents the changes to be made in the code of an "honest validator" to implement the EIP-4788 feature.
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## Prerequisites
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This document is an extension of the [Capella -- Honest Validator](../capella/validator.md) guide.
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All behaviors and definitions defined in this document, and documents it extends, carry over unless explicitly noted or overridden.
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All terminology, constants, functions, and protocol mechanics defined in the updated Beacon Chain doc of [Capella](../capella/beacon-chain.md) are requisite for this document and used throughout.
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Please see related Beacon Chain doc before continuing and use them as a reference throughout.
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## Helpers
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## Protocols
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### `ExecutionEngine`
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#### `get_payload`
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`get_payload` returns the upgraded EIP-4788 `ExecutionPayload` type.
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## Beacon chain responsibilities
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All validator responsibilities remain unchanged other than those noted below.
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### Block proposal
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#### Constructing the `BeaconBlockBody`
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##### ExecutionPayload
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`ExecutionPayload`s are constructed as they were in Capella, except that the parent beacon block root is also supplied.
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*Note*: In this section, `state` is the state of the slot for the block proposal _without_ the block yet applied.
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That is, `state` is the `previous_state` processed through any empty slots up to the assigned slot using `process_slots(previous_state, slot)`.
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*Note*: The only change made to `prepare_execution_payload` is to add the parent beacon block root as an additional
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parameter to the `PayloadAttributes`.
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```python
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def prepare_execution_payload(state: BeaconState,
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pow_chain: Dict[Hash32, PowBlock],
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safe_block_hash: Hash32,
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finalized_block_hash: Hash32,
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suggested_fee_recipient: ExecutionAddress,
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execution_engine: ExecutionEngine) -> Optional[PayloadId]:
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if not is_merge_transition_complete(state):
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is_terminal_block_hash_set = TERMINAL_BLOCK_HASH != Hash32()
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is_activation_epoch_reached = get_current_epoch(state) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH
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if is_terminal_block_hash_set and not is_activation_epoch_reached:
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# Terminal block hash is set but activation epoch is not yet reached, no prepare payload call is needed
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return None
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terminal_pow_block = get_terminal_pow_block(pow_chain)
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if terminal_pow_block is None:
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# Pre-merge, no prepare payload call is needed
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return None
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# Signify merge via producing on top of the terminal PoW block
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parent_hash = terminal_pow_block.block_hash
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else:
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# Post-merge, normal payload
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parent_hash = state.latest_execution_payload_header.block_hash
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# Set the forkchoice head and initiate the payload build process
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payload_attributes = PayloadAttributes(
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timestamp=compute_timestamp_at_slot(state, state.slot),
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prev_randao=get_randao_mix(state, get_current_epoch(state)),
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suggested_fee_recipient=suggested_fee_recipient,
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withdrawals=get_expected_withdrawals(state),
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parent_beacon_block_root=hash_tree_root(state.latest_block_header), # [New in EIP-4788]
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)
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return execution_engine.notify_forkchoice_updated(
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head_block_hash=parent_hash,
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safe_block_hash=safe_block_hash,
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finalized_block_hash=finalized_block_hash,
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payload_attributes=payload_attributes,
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)
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```
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