use crate::checkpoint::CheckPoint; use crate::errors::{BeaconChainError as Error, BlockProductionError}; use db::{ stores::{BeaconBlockStore, BeaconStateStore}, ClientDB, DBError, }; use fork_choice::{ForkChoice, ForkChoiceError}; use log::{debug, trace}; use operation_pool::DepositInsertStatus; use operation_pool::OperationPool; use parking_lot::{RwLock, RwLockReadGuard}; use slot_clock::SlotClock; use ssz::ssz_encode; use state_processing::per_block_processing::errors::{ AttestationValidationError, AttesterSlashingValidationError, DepositValidationError, ExitValidationError, ProposerSlashingValidationError, TransferValidationError, }; use state_processing::{ per_block_processing, per_block_processing_without_verifying_block_signature, per_slot_processing, BlockProcessingError, SlotProcessingError, }; use std::sync::Arc; use types::*; #[derive(Debug, PartialEq)] pub enum ValidBlock { /// The block was successfully processed. Processed, } #[derive(Debug, PartialEq)] pub enum InvalidBlock { /// The block slot is greater than the present slot. FutureSlot { present_slot: Slot, block_slot: Slot, }, /// The block state_root does not match the generated state. StateRootMismatch, /// The blocks parent_root is unknown. ParentUnknown, /// There was an error whilst advancing the parent state to the present slot. This condition /// should not occur, it likely represents an internal error. SlotProcessingError(SlotProcessingError), /// The block could not be applied to the state, it is invalid. PerBlockProcessingError(BlockProcessingError), } #[derive(Debug, PartialEq)] pub enum BlockProcessingOutcome { /// The block was successfully validated. ValidBlock(ValidBlock), /// The block was not successfully validated. InvalidBlock(InvalidBlock), } impl BlockProcessingOutcome { /// Returns `true` if the block was objectively invalid and we should disregard the peer who /// sent it. pub fn is_invalid(&self) -> bool { match self { BlockProcessingOutcome::ValidBlock(_) => false, BlockProcessingOutcome::InvalidBlock(r) => match r { InvalidBlock::FutureSlot { .. } => true, InvalidBlock::StateRootMismatch => true, InvalidBlock::ParentUnknown => false, InvalidBlock::SlotProcessingError(_) => false, InvalidBlock::PerBlockProcessingError(e) => match e { BlockProcessingError::Invalid(_) => true, BlockProcessingError::BeaconStateError(_) => false, }, }, } } /// Returns `true` if the block was successfully processed and can be removed from any import /// queues or temporary storage. pub fn sucessfully_processed(&self) -> bool { match self { BlockProcessingOutcome::ValidBlock(_) => true, _ => false, } } } pub struct BeaconChain { pub block_store: Arc>, pub state_store: Arc>, pub slot_clock: U, pub op_pool: OperationPool, canonical_head: RwLock, finalized_head: RwLock, pub state: RwLock, pub spec: ChainSpec, pub fork_choice: RwLock, } impl BeaconChain where T: ClientDB, U: SlotClock, F: ForkChoice, { /// Instantiate a new Beacon Chain, from genesis. pub fn from_genesis( state_store: Arc>, block_store: Arc>, slot_clock: U, mut genesis_state: BeaconState, genesis_block: BeaconBlock, spec: ChainSpec, fork_choice: F, ) -> Result { let state_root = genesis_state.canonical_root(); state_store.put(&state_root, &ssz_encode(&genesis_state)[..])?; let block_root = genesis_block.block_header().canonical_root(); block_store.put(&block_root, &ssz_encode(&genesis_block)[..])?; let finalized_head = RwLock::new(CheckPoint::new( genesis_block.clone(), block_root, genesis_state.clone(), state_root, )); let canonical_head = RwLock::new(CheckPoint::new( genesis_block.clone(), block_root, genesis_state.clone(), state_root, )); genesis_state.build_all_caches(&spec)?; Ok(Self { block_store, state_store, slot_clock, op_pool: OperationPool::new(), state: RwLock::new(genesis_state), finalized_head, canonical_head, spec, fork_choice: RwLock::new(fork_choice), }) } /// Returns the beacon block body for each beacon block root in `roots`. /// /// Fails if any root in `roots` does not have a corresponding block. pub fn get_block_bodies(&self, roots: &[Hash256]) -> Result, Error> { let bodies: Result, _> = roots .iter() .map(|root| match self.get_block(root)? { Some(block) => Ok(block.body), None => Err(Error::DBInconsistent("Missing block".into())), }) .collect(); Ok(bodies?) } /// Returns the beacon block header for each beacon block root in `roots`. /// /// Fails if any root in `roots` does not have a corresponding block. pub fn get_block_headers(&self, roots: &[Hash256]) -> Result, Error> { let headers: Result, _> = roots .iter() .map(|root| match self.get_block(root)? { Some(block) => Ok(block.block_header()), None => Err(Error::DBInconsistent("Missing block".into())), }) .collect(); Ok(headers?) } /// Returns `count `beacon block roots, starting from `start_slot` with an /// interval of `skip` slots between each root. /// /// ## Errors: /// /// - `SlotOutOfBounds`: Unable to return the full specified range. /// - `SlotOutOfBounds`: Unable to load a state from the DB. /// - `SlotOutOfBounds`: Start slot is higher than the first slot. /// - Other: BeaconState` is inconsistent. pub fn get_block_roots( &self, earliest_slot: Slot, count: usize, skip: usize, ) -> Result, Error> { let spec = &self.spec; let step_by = Slot::from(skip + 1); let mut roots: Vec = vec![]; // The state for reading block roots. Will be updated with an older state if slots go too // far back in history. let mut state = self.state.read().clone(); // The final slot in this series, will be reduced by `skip` each loop iteration. let mut slot = earliest_slot + Slot::from(count * (skip + 1)) - 1; // If the highest slot requested is that of the current state insert the root of the // head block, unless the head block's slot is not matching. if slot == state.slot && self.head().beacon_block.slot == slot { roots.push(self.head().beacon_block_root); slot -= step_by; } else if slot >= state.slot { return Err(BeaconStateError::SlotOutOfBounds.into()); } loop { // If the slot is within the range of the current state's block roots, append the root // to the output vec. // // If we get `SlotOutOfBounds` error, load the oldest available historic // state from the DB. match state.get_block_root(slot, spec) { Ok(root) => { if slot < earliest_slot { break; } else { roots.push(*root); slot -= step_by; } } Err(BeaconStateError::SlotOutOfBounds) => { // Read the earliest historic state in the current slot. let earliest_historic_slot = state.slot - Slot::from(spec.slots_per_historical_root); // Load the earlier state from disk. let new_state_root = state.get_state_root(earliest_historic_slot, spec)?; // Break if the DB is unable to load the state. state = match self.state_store.get_deserialized(&new_state_root) { Ok(Some(state)) => state, _ => break, } } Err(e) => return Err(e.into()), }; } // Return the results if they pass a sanity check. if (slot <= earliest_slot) && (roots.len() == count) { // Reverse the ordering of the roots. We extracted them in reverse order to make it // simpler to lookup historic states. // // This is a potential optimisation target. Ok(roots.iter().rev().cloned().collect()) } else { Err(BeaconStateError::SlotOutOfBounds.into()) } } /// Returns the block at the given root, if any. /// /// ## Errors /// /// May return a database error. pub fn get_block(&self, block_root: &Hash256) -> Result, Error> { Ok(self.block_store.get_deserialized(block_root)?) } /// Update the canonical head to some new values. pub fn update_canonical_head( &self, new_beacon_block: BeaconBlock, new_beacon_block_root: Hash256, new_beacon_state: BeaconState, new_beacon_state_root: Hash256, ) { debug!( "Updating canonical head with block at slot: {}", new_beacon_block.slot ); let mut head = self.canonical_head.write(); head.update( new_beacon_block, new_beacon_block_root, new_beacon_state, new_beacon_state_root, ); } /// Returns a read-lock guarded `CheckPoint` struct for reading the head (as chosen by the /// fork-choice rule). /// /// It is important to note that the `beacon_state` returned may not match the present slot. It /// is the state as it was when the head block was recieved, which could be some slots prior to /// now. pub fn head(&self) -> RwLockReadGuard { self.canonical_head.read() } /// Updates the canonical `BeaconState` with the supplied state. /// /// Advances the chain forward to the present slot. This method is better than just setting /// state and calling `catchup_state` as it will not result in an old state being installed and /// then having it iteratively updated -- in such a case it's possible for another thread to /// find the state at an old slot. pub fn update_state(&self, mut state: BeaconState) -> Result<(), Error> { let latest_block_header = self.head().beacon_block.block_header(); let present_slot = match self.slot_clock.present_slot() { Ok(Some(slot)) => slot, _ => return Err(Error::UnableToReadSlot), }; // If required, transition the new state to the present slot. for _ in state.slot.as_u64()..present_slot.as_u64() { per_slot_processing(&mut state, &latest_block_header, &self.spec)?; } state.build_all_caches(&self.spec)?; *self.state.write() = state; Ok(()) } /// Ensures the current canonical `BeaconState` has been transitioned to match the `slot_clock`. pub fn catchup_state(&self) -> Result<(), Error> { let latest_block_header = self.head().beacon_block.block_header(); let present_slot = match self.slot_clock.present_slot() { Ok(Some(slot)) => slot, _ => return Err(Error::UnableToReadSlot), }; let mut state = self.state.write(); // If required, transition the new state to the present slot. for _ in state.slot.as_u64()..present_slot.as_u64() { // Ensure the next epoch state caches are built in case of an epoch transition. state.build_epoch_cache(RelativeEpoch::NextWithoutRegistryChange, &self.spec)?; state.build_epoch_cache(RelativeEpoch::NextWithRegistryChange, &self.spec)?; per_slot_processing(&mut *state, &latest_block_header, &self.spec)?; } state.build_all_caches(&self.spec)?; Ok(()) } /// Build all of the caches on the current state. /// /// Ideally this shouldn't be required, however we leave it here for testing. pub fn ensure_state_caches_are_built(&self) -> Result<(), Error> { self.state.write().build_all_caches(&self.spec)?; Ok(()) } /// Update the justified head to some new values. pub fn update_finalized_head( &self, new_beacon_block: BeaconBlock, new_beacon_block_root: Hash256, new_beacon_state: BeaconState, new_beacon_state_root: Hash256, ) { let mut finalized_head = self.finalized_head.write(); finalized_head.update( new_beacon_block, new_beacon_block_root, new_beacon_state, new_beacon_state_root, ); } /// Returns a read-lock guarded `CheckPoint` struct for reading the justified head (as chosen, /// indirectly, by the fork-choice rule). pub fn finalized_head(&self) -> RwLockReadGuard { self.finalized_head.read() } /// Returns the validator index (if any) for the given public key. /// /// Information is retrieved from the present `beacon_state.validator_registry`. pub fn validator_index(&self, pubkey: &PublicKey) -> Option { for (i, validator) in self .head() .beacon_state .validator_registry .iter() .enumerate() { if validator.pubkey == *pubkey { return Some(i); } } None } /// Reads the slot clock, returns `None` if the slot is unavailable. /// /// The slot might be unavailable due to an error with the system clock, or if the present time /// is before genesis (i.e., a negative slot). /// /// This is distinct to `present_slot`, which simply reads the latest state. If a /// call to `read_slot_clock` results in a higher slot than a call to `present_slot`, /// `self.state` should undergo per slot processing. pub fn read_slot_clock(&self) -> Option { match self.slot_clock.present_slot() { Ok(Some(some_slot)) => Some(some_slot), Ok(None) => None, _ => None, } } /// Reads the slot clock (see `self.read_slot_clock()` and returns the number of slots since /// genesis. pub fn slots_since_genesis(&self) -> Option { let now = self.read_slot_clock()?; if now < self.spec.genesis_slot { None } else { Some(SlotHeight::from( now.as_u64() - self.spec.genesis_slot.as_u64(), )) } } /// Returns slot of the present state. /// /// This is distinct to `read_slot_clock`, which reads from the actual system clock. If /// `self.state` has not been transitioned it is possible for the system clock to be on a /// different slot to what is returned from this call. pub fn present_slot(&self) -> Slot { self.state.read().slot } /// Returns the block proposer for a given slot. /// /// Information is read from the present `beacon_state` shuffling, so only information from the /// present and prior epoch is available. pub fn block_proposer(&self, slot: Slot) -> Result { self.state .write() .build_epoch_cache(RelativeEpoch::Current, &self.spec)?; let index = self.state.read().get_beacon_proposer_index( slot, RelativeEpoch::Current, &self.spec, )?; Ok(index) } /// Returns the attestation slot and shard for a given validator index. /// /// Information is read from the current state, so only information from the present and prior /// epoch is available. pub fn validator_attestion_slot_and_shard( &self, validator_index: usize, ) -> Result, BeaconStateError> { trace!( "BeaconChain::validator_attestion_slot_and_shard: validator_index: {}", validator_index ); if let Some(attestation_duty) = self .state .read() .get_attestation_duties(validator_index, &self.spec)? { Ok(Some((attestation_duty.slot, attestation_duty.shard))) } else { Ok(None) } } /// Produce an `AttestationData` that is valid for the present `slot` and given `shard`. pub fn produce_attestation_data(&self, shard: u64) -> Result { trace!("BeaconChain::produce_attestation: shard: {}", shard); let state = self.state.read(); let target_root = *self.state.read().get_block_root( self.state .read() .slot .epoch(self.spec.slots_per_epoch) .start_slot(self.spec.slots_per_epoch), &self.spec, )?; Ok(AttestationData { slot: self.state.read().slot, shard, beacon_block_root: self.head().beacon_block_root, target_root, crosslink_data_root: Hash256::zero(), previous_crosslink: state.latest_crosslinks[shard as usize].clone(), source_epoch: state.current_justified_epoch, source_root: state.current_justified_root, }) } /// Accept a new attestation from the network. /// /// If valid, the attestation is added to the `op_pool` and aggregated with another attestation /// if possible. pub fn process_attestation( &self, attestation: Attestation, ) -> Result<(), AttestationValidationError> { self.op_pool .insert_attestation(attestation, &*self.state.read(), &self.spec) } /// Accept some deposit and queue it for inclusion in an appropriate block. pub fn process_deposit( &self, deposit: Deposit, ) -> Result { self.op_pool .insert_deposit(deposit, &*self.state.read(), &self.spec) } /// Accept some exit and queue it for inclusion in an appropriate block. pub fn process_voluntary_exit(&self, exit: VoluntaryExit) -> Result<(), ExitValidationError> { self.op_pool .insert_voluntary_exit(exit, &*self.state.read(), &self.spec) } /// Accept some transfer and queue it for inclusion in an appropriate block. pub fn process_transfer(&self, transfer: Transfer) -> Result<(), TransferValidationError> { self.op_pool .insert_transfer(transfer, &*self.state.read(), &self.spec) } /// Accept some proposer slashing and queue it for inclusion in an appropriate block. pub fn process_proposer_slashing( &self, proposer_slashing: ProposerSlashing, ) -> Result<(), ProposerSlashingValidationError> { self.op_pool .insert_proposer_slashing(proposer_slashing, &*self.state.read(), &self.spec) } /// Accept some attester slashing and queue it for inclusion in an appropriate block. pub fn process_attester_slashing( &self, attester_slashing: AttesterSlashing, ) -> Result<(), AttesterSlashingValidationError> { self.op_pool .insert_attester_slashing(attester_slashing, &*self.state.read(), &self.spec) } /// Accept some block and attempt to add it to block DAG. /// /// Will accept blocks from prior slots, however it will reject any block from a future slot. pub fn process_block(&self, block: BeaconBlock) -> Result { debug!("Processing block with slot {}...", block.slot); let block_root = block.block_header().canonical_root(); let present_slot = self.present_slot(); if block.slot > present_slot { return Ok(BlockProcessingOutcome::InvalidBlock( InvalidBlock::FutureSlot { present_slot, block_slot: block.slot, }, )); } // Load the blocks parent block from the database, returning invalid if that block is not // found. let parent_block_root = block.previous_block_root; let parent_block = match self.block_store.get_deserialized(&parent_block_root)? { Some(previous_block_root) => previous_block_root, None => { return Ok(BlockProcessingOutcome::InvalidBlock( InvalidBlock::ParentUnknown, )); } }; // Load the parent blocks state from the database, returning an error if it is not found. // It is an error because if know the parent block we should also know the parent state. let parent_state_root = parent_block.state_root; let parent_state = self .state_store .get_deserialized(&parent_state_root)? .ok_or_else(|| Error::DBInconsistent(format!("Missing state {}", parent_state_root)))?; // TODO: check the block proposer signature BEFORE doing a state transition. This will // significantly lower exposure surface to DoS attacks. // Transition the parent state to the block slot. let mut state = parent_state; let previous_block_header = parent_block.block_header(); for _ in state.slot.as_u64()..block.slot.as_u64() { if let Err(e) = per_slot_processing(&mut state, &previous_block_header, &self.spec) { return Ok(BlockProcessingOutcome::InvalidBlock( InvalidBlock::SlotProcessingError(e), )); } } // Apply the received block to its parent state (which has been transitioned into this // slot). if let Err(e) = per_block_processing(&mut state, &block, &self.spec) { return Ok(BlockProcessingOutcome::InvalidBlock( InvalidBlock::PerBlockProcessingError(e), )); } let state_root = state.canonical_root(); if block.state_root != state_root { return Ok(BlockProcessingOutcome::InvalidBlock( InvalidBlock::StateRootMismatch, )); } // Store the block and state. self.block_store.put(&block_root, &ssz_encode(&block)[..])?; self.state_store.put(&state_root, &ssz_encode(&state)[..])?; // run the fork_choice add_block logic self.fork_choice .write() .add_block(&block, &block_root, &self.spec)?; // If the parent block was the parent_block, automatically update the canonical head. // // TODO: this is a first-in-best-dressed scenario that is not ideal; fork_choice should be // run instead. if self.head().beacon_block_root == parent_block_root { self.update_canonical_head(block.clone(), block_root, state.clone(), state_root); // Update the canonical `BeaconState`. self.update_state(state)?; } Ok(BlockProcessingOutcome::ValidBlock(ValidBlock::Processed)) } /// Produce a new block at the present slot. /// /// The produced block will not be inherently valid, it must be signed by a block producer. /// Block signing is out of the scope of this function and should be done by a separate program. pub fn produce_block( &self, randao_reveal: Signature, ) -> Result<(BeaconBlock, BeaconState), BlockProductionError> { debug!("Producing block at slot {}...", self.state.read().slot); let mut state = self.state.read().clone(); state.build_epoch_cache(RelativeEpoch::Current, &self.spec)?; trace!("Finding attestations for new block..."); let previous_block_root = *state .get_block_root(state.slot - 1, &self.spec) .map_err(|_| BlockProductionError::UnableToGetBlockRootFromState)?; let (proposer_slashings, attester_slashings) = self.op_pool.get_slashings(&*self.state.read(), &self.spec); let mut block = BeaconBlock { slot: state.slot, previous_block_root, state_root: Hash256::zero(), // Updated after the state is calculated. signature: self.spec.empty_signature.clone(), // To be completed by a validator. body: BeaconBlockBody { randao_reveal, eth1_data: Eth1Data { // TODO: replace with real data deposit_root: Hash256::zero(), block_hash: Hash256::zero(), }, proposer_slashings, attester_slashings, attestations: self .op_pool .get_attestations(&*self.state.read(), &self.spec), deposits: self.op_pool.get_deposits(&*self.state.read(), &self.spec), voluntary_exits: self .op_pool .get_voluntary_exits(&*self.state.read(), &self.spec), transfers: self.op_pool.get_transfers(&*self.state.read(), &self.spec), }, }; debug!( "Produced block with {} attestations, updating state.", block.body.attestations.len() ); per_block_processing_without_verifying_block_signature(&mut state, &block, &self.spec)?; let state_root = state.canonical_root(); block.state_root = state_root; Ok((block, state)) } // TODO: Left this as is, modify later pub fn fork_choice(&self) -> Result<(), Error> { let present_head = self.finalized_head().beacon_block_root; let new_head = self .fork_choice .write() .find_head(&present_head, &self.spec)?; if new_head != present_head { let block = self .block_store .get_deserialized(&new_head)? .ok_or_else(|| Error::MissingBeaconBlock(new_head))?; let block_root = block.canonical_root(); let state = self .state_store .get_deserialized(&block.state_root)? .ok_or_else(|| Error::MissingBeaconState(block.state_root))?; let state_root = state.canonical_root(); self.update_canonical_head(block, block_root, state.clone(), state_root); // Update the canonical `BeaconState`. self.update_state(state)?; } Ok(()) } /// Returns `true` if the given block root has not been processed. pub fn is_new_block_root(&self, beacon_block_root: &Hash256) -> Result { Ok(!self.block_store.exists(beacon_block_root)?) } /// Dumps the entire canonical chain, from the head to genesis to a vector for analysis. /// /// This could be a very expensive operation and should only be done in testing/analysis /// activities. pub fn chain_dump(&self) -> Result, Error> { let mut dump = vec![]; let mut last_slot = CheckPoint { beacon_block: self.head().beacon_block.clone(), beacon_block_root: self.head().beacon_block_root, beacon_state: self.head().beacon_state.clone(), beacon_state_root: self.head().beacon_state_root, }; dump.push(last_slot.clone()); loop { let beacon_block_root = last_slot.beacon_block.previous_block_root; if beacon_block_root == self.spec.zero_hash { break; // Genesis has been reached. } let beacon_block = self .block_store .get_deserialized(&beacon_block_root)? .ok_or_else(|| { Error::DBInconsistent(format!("Missing block {}", beacon_block_root)) })?; let beacon_state_root = beacon_block.state_root; let beacon_state = self .state_store .get_deserialized(&beacon_state_root)? .ok_or_else(|| { Error::DBInconsistent(format!("Missing state {}", beacon_state_root)) })?; let slot = CheckPoint { beacon_block, beacon_block_root, beacon_state, beacon_state_root, }; dump.push(slot.clone()); last_slot = slot; } dump.reverse(); Ok(dump) } } impl From for Error { fn from(e: DBError) -> Error { Error::DBError(e.message) } } impl From for Error { fn from(e: ForkChoiceError) -> Error { Error::ForkChoiceError(e) } } impl From for Error { fn from(e: BeaconStateError) -> Error { Error::BeaconStateError(e) } }