lighthouse/beacon_node/beacon_chain/src/fork_revert.rs

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use crate::{BeaconForkChoiceStore, BeaconSnapshot};
use fork_choice::{ForkChoice, PayloadVerificationStatus};
use itertools::process_results;
use slog::{info, warn, Logger};
use state_processing::state_advance::complete_state_advance;
use state_processing::{per_block_processing, per_block_processing::BlockSignatureStrategy};
use std::sync::Arc;
use store::{iter::ParentRootBlockIterator, HotColdDB, ItemStore};
use types::{BeaconState, ChainSpec, EthSpec, ForkName, Hash256, SignedBeaconBlock, Slot};
const CORRUPT_DB_MESSAGE: &str = "The database could be corrupt. Check its file permissions or \
consider deleting it by running with the --purge-db flag.";
/// Revert the head to the last block before the most recent hard fork.
///
/// This function is destructive and should only be used if there is no viable alternative. It will
/// cause the reverted blocks and states to be completely forgotten, lying dormant in the database
/// forever.
///
/// Return the `(head_block_root, head_block)` that should be used post-reversion.
pub fn revert_to_fork_boundary<E: EthSpec, Hot: ItemStore<E>, Cold: ItemStore<E>>(
current_slot: Slot,
head_block_root: Hash256,
store: Arc<HotColdDB<E, Hot, Cold>>,
spec: &ChainSpec,
log: &Logger,
) -> Result<(Hash256, SignedBeaconBlock<E>), String> {
let current_fork = spec.fork_name_at_slot::<E>(current_slot);
let fork_epoch = spec
.fork_epoch(current_fork)
.ok_or_else(|| format!("Current fork '{}' never activates", current_fork))?;
if current_fork == ForkName::Base {
return Err(format!(
"Cannot revert to before phase0 hard fork. {}",
CORRUPT_DB_MESSAGE
));
}
warn!(
log,
"Reverting invalid head block";
"target_fork" => %current_fork,
"fork_epoch" => fork_epoch,
);
let block_iter = ParentRootBlockIterator::fork_tolerant(&store, head_block_root);
process_results(block_iter, |mut iter| {
iter.find_map(|(block_root, block)| {
if block.slot() < fork_epoch.start_slot(E::slots_per_epoch()) {
Some((block_root, block))
} else {
info!(
log,
"Reverting block";
"block_root" => ?block_root,
"slot" => block.slot(),
);
None
}
})
})
.map_err(|e| {
format!(
"Error fetching blocks to revert: {:?}. {}",
e, CORRUPT_DB_MESSAGE
)
})?
.ok_or_else(|| format!("No pre-fork blocks found. {}", CORRUPT_DB_MESSAGE))
}
/// Reset fork choice to the finalized checkpoint of the supplied head state.
///
/// The supplied `head_block_root` should correspond to the most recently applied block on
/// `head_state`.
///
/// This function avoids quirks of fork choice initialization by replaying all of the blocks from
/// the checkpoint to the head.
///
/// See this issue for details: https://github.com/ethereum/consensus-specs/issues/2566
///
/// It will fail if the finalized state or any of the blocks to replay are unavailable.
///
/// WARNING: this function is destructive and causes fork choice to permanently forget all
/// chains other than the chain leading to `head_block_root`. It should only be used in extreme
/// circumstances when there is no better alternative.
pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: ItemStore<E>>(
head_block_root: Hash256,
head_state: &BeaconState<E>,
store: Arc<HotColdDB<E, Hot, Cold>>,
spec: &ChainSpec,
) -> Result<ForkChoice<BeaconForkChoiceStore<E, Hot, Cold>, E>, String> {
// Fetch finalized block.
let finalized_checkpoint = head_state.finalized_checkpoint();
let finalized_block_root = finalized_checkpoint.root;
let finalized_block = store
.get_block(&finalized_block_root)
.map_err(|e| format!("Error loading finalized block: {:?}", e))?
.ok_or_else(|| {
format!(
"Finalized block missing for revert: {:?}",
finalized_block_root
)
})?;
// Advance finalized state to finalized epoch (to handle skipped slots).
let finalized_state_root = finalized_block.state_root();
let mut finalized_state = store
.get_state(&finalized_state_root, Some(finalized_block.slot()))
.map_err(|e| format!("Error loading finalized state: {:?}", e))?
.ok_or_else(|| {
format!(
"Finalized block state missing from database: {:?}",
finalized_state_root
)
})?;
let finalized_slot = finalized_checkpoint.epoch.start_slot(E::slots_per_epoch());
complete_state_advance(
&mut finalized_state,
Some(finalized_state_root),
finalized_slot,
spec,
)
.map_err(|e| {
format!(
"Error advancing finalized state to finalized epoch: {:?}",
e
)
})?;
let finalized_snapshot = BeaconSnapshot {
beacon_block_root: finalized_block_root,
beacon_block: finalized_block,
beacon_state: finalized_state,
};
let fc_store = BeaconForkChoiceStore::get_forkchoice_store(store.clone(), &finalized_snapshot);
let mut fork_choice = ForkChoice::from_anchor(
fc_store,
finalized_block_root,
&finalized_snapshot.beacon_block,
&finalized_snapshot.beacon_state,
)
.map_err(|e| format!("Unable to reset fork choice for revert: {:?}", e))?;
// Replay blocks from finalized checkpoint back to head.
// We do not replay attestations presently, relying on the absence of other blocks
// to guarantee `head_block_root` as the head.
let blocks = store
.load_blocks_to_replay(finalized_slot + 1, head_state.slot(), head_block_root)
.map_err(|e| format!("Error loading blocks to replay for fork choice: {:?}", e))?;
let mut state = finalized_snapshot.beacon_state;
for block in blocks {
complete_state_advance(&mut state, None, block.slot(), spec)
.map_err(|e| format!("State advance failed: {:?}", e))?;
per_block_processing(
&mut state,
&block,
None,
BlockSignatureStrategy::NoVerification,
spec,
)
.map_err(|e| format!("Error replaying block: {:?}", e))?;
// Setting this to unverified is the safest solution, since we don't have a way to
// retro-actively determine if they were valid or not.
//
// This scenario is so rare that it seems OK to double-verify some blocks.
let payload_verification_status = PayloadVerificationStatus::NotVerified;
let (block, _) = block.deconstruct();
fork_choice
.on_block(
block.slot(),
&block,
block.canonical_root(),
&state,
payload_verification_status,
)
.map_err(|e| format!("Error applying replayed block to fork choice: {:?}", e))?;
}
Ok(fork_choice)
}