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/* This file is part of DarkFi (https://dark.fi)
*
* Copyright (C) 2020-2024 Dyne.org foundation
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
use std::{collections::HashMap, sync::Arc};
use darkfi_sdk::crypto::MerkleTree;
use log::{debug, error, info, warn};
use num_bigint::BigUint;
use smol::lock::RwLock;
use crate::{
blockchain::{
block_store::{BlockDifficulty, BlockInfo, BlockRanks},
Blockchain, BlockchainOverlay, HeaderHash,
},
error::TxVerifyFailed,
tx::Transaction,
zk::VerifyingKey,
Error, Result,
};
/// DarkFi consensus module
pub mod consensus;
use consensus::{Consensus, Fork, Proposal};
/// DarkFi PoW module
pub mod pow;
use pow::PoWModule;
/// Verification functions
pub mod verification;
use verification::{
verify_block, verify_checkpoint_block, verify_genesis_block, verify_producer_transaction,
verify_transaction, verify_transactions,
};
/// Fee calculation helpers
pub mod fees;
/// Helper utilities
pub mod utils;
use utils::{best_fork_index, block_rank, deploy_native_contracts};
/// Configuration for initializing [`Validator`]
#[derive(Clone)]
pub struct ValidatorConfig {
/// Currently configured finalization security threshold
pub finalization_threshold: usize,
/// Currently configured PoW target
pub pow_target: u32,
/// Optional fixed difficulty, for testing purposes
pub pow_fixed_difficulty: Option<BigUint>,
/// Genesis block
pub genesis_block: BlockInfo,
/// Flag to enable tx fee verification
pub verify_fees: bool,
}
/// Atomic pointer to validator.
pub type ValidatorPtr = Arc<Validator>;
/// This struct represents a DarkFi validator node.
pub struct Validator {
/// Canonical (finalized) blockchain
pub blockchain: Blockchain,
/// Hot/Live data used by the consensus algorithm
pub consensus: Consensus,
/// Flag signalling node has finished initial sync
pub synced: RwLock<bool>,
/// Flag to enable tx fee verification
pub verify_fees: bool,
}
impl Validator {
pub async fn new(db: &sled::Db, config: ValidatorConfig) -> Result<ValidatorPtr> {
info!(target: "validator::new", "Initializing Validator");
info!(target: "validator::new", "Initializing Blockchain");
let blockchain = Blockchain::new(db)?;
// Create an overlay over whole blockchain so we can write stuff
let overlay = BlockchainOverlay::new(&blockchain)?;
// Deploy native wasm contracts
deploy_native_contracts(&overlay, config.pow_target).await?;
// Add genesis block if blockchain is empty
if blockchain.genesis().is_err() {
info!(target: "validator::new", "Appending genesis block");
verify_genesis_block(&overlay, &config.genesis_block, config.pow_target).await?;
};
// Write the changes to the actual chain db
overlay.lock().unwrap().overlay.lock().unwrap().apply()?;
info!(target: "validator::new", "Initializing Consensus");
let consensus = Consensus::new(
blockchain.clone(),
config.finalization_threshold,
config.pow_target,
config.pow_fixed_difficulty,
)?;
// Create the actual state
let state = Arc::new(Self {
blockchain,
consensus,
synced: RwLock::new(false),
verify_fees: config.verify_fees,
});
info!(target: "validator::new", "Finished initializing validator");
Ok(state)
}
/// Auxiliary function to compute provided transaction's total gas,
/// against current best fork.
/// The function takes a boolean called `verify_fee` to overwrite
/// the nodes configured `verify_fees` flag.
pub async fn calculate_gas(&self, tx: &Transaction, verify_fee: bool) -> Result<u64> {
// Grab the best fork to verify against
let forks = self.consensus.forks.read().await;
let fork = forks[best_fork_index(&forks)?].full_clone()?;
drop(forks);
// Map of ZK proof verifying keys for the transaction
let mut vks: HashMap<[u8; 32], HashMap<String, VerifyingKey>> = HashMap::new();
for call in &tx.calls {
vks.insert(call.data.contract_id.to_bytes(), HashMap::new());
}
// Grab forks' next block height
let next_block_height = fork.get_next_block_height()?;
// Verify transaction to grab the gas used
let verify_result = verify_transaction(
&fork.overlay,
next_block_height,
self.consensus.module.read().await.target,
tx,
&mut MerkleTree::new(1),
&mut vks,
verify_fee,
)
.await;
// Purge new trees
fork.overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
Ok(verify_result?.0)
}
/// The node retrieves a transaction, validates its state transition,
/// and appends it to the pending txs store.
pub async fn append_tx(&self, tx: &Transaction, write: bool) -> Result<()> {
let tx_hash = tx.hash();
// Check if we have already seen this tx
let tx_in_txstore = self.blockchain.transactions.contains(&tx_hash)?;
let tx_in_pending_txs_store = self.blockchain.transactions.contains_pending(&tx_hash)?;
if tx_in_txstore || tx_in_pending_txs_store {
info!(target: "validator::append_tx", "We have already seen this tx");
return Err(TxVerifyFailed::AlreadySeenTx(tx_hash.as_string()).into())
}
// Verify state transition
info!(target: "validator::append_tx", "Starting state transition validation");
let tx_vec = [tx.clone()];
let mut valid = false;
// Grab a lock over current consensus forks state
let mut forks = self.consensus.forks.write().await;
// Iterate over node forks to verify transaction validity in their overlays
for fork in forks.iter_mut() {
// Clone fork state
let fork_clone = fork.full_clone()?;
// Grab forks' next block height
let next_block_height = fork_clone.get_next_block_height()?;
// Verify transaction
let verify_result = verify_transactions(
&fork_clone.overlay,
next_block_height,
self.consensus.module.read().await.target,
&tx_vec,
&mut MerkleTree::new(1),
self.verify_fees,
)
.await;
// Purge new trees
fork_clone.overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
// Handle response
match verify_result {
Ok(_) => {}
Err(Error::TxVerifyFailed(TxVerifyFailed::ErroneousTxs(_))) => continue,
Err(e) => return Err(e),
}
valid = true;
// Store transaction hash in forks' mempool
if write {
fork.mempool.push(tx_hash);
}
}
// Drop forks lock
drop(forks);
// Return error if transaction is not valid for any fork
if !valid {
return Err(TxVerifyFailed::ErroneousTxs(tx_vec.to_vec()).into())
}
// Add transaction to pending txs store
if write {
self.blockchain.add_pending_txs(&tx_vec)?;
info!(target: "validator::append_tx", "Appended tx to pending txs store");
}
Ok(())
}
/// The node removes invalid transactions from the pending txs store.
pub async fn purge_pending_txs(&self) -> Result<()> {
info!(target: "validator::purge_pending_txs", "Removing invalid transactions from pending transactions store...");
// Check if any pending transactions exist
let pending_txs = self.blockchain.get_pending_txs()?;
if pending_txs.is_empty() {
info!(target: "validator::purge_pending_txs", "No pending transactions found");
return Ok(())
}
// Grab a lock over current consensus forks state
let mut forks = self.consensus.forks.write().await;
let mut removed_txs = vec![];
for tx in pending_txs {
let tx_hash = tx.hash();
let tx_vec = [tx.clone()];
let mut valid = false;
// Iterate over node forks to verify transaction validity in their overlays
for fork in forks.iter_mut() {
// Clone fork state
let fork_clone = fork.full_clone()?;
// Grab forks' next block height
let next_block_height = fork_clone.get_next_block_height()?;
// Verify transaction
let verify_result = verify_transactions(
&fork_clone.overlay,
next_block_height,
self.consensus.module.read().await.target,
&tx_vec,
&mut MerkleTree::new(1),
self.verify_fees,
)
.await;
// Purge new trees
fork_clone.overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
// Handle response
match verify_result {
Ok(_) => {
valid = true;
continue
}
Err(Error::TxVerifyFailed(TxVerifyFailed::ErroneousTxs(_))) => {}
Err(e) => return Err(e),
}
// Remove erroneous transaction from forks' mempool
fork.mempool.retain(|x| *x != tx_hash);
}
// Remove pending transaction if it's not valid for canonical or any fork
if !valid {
removed_txs.push(tx)
}
}
// Drop forks lock
drop(forks);
if removed_txs.is_empty() {
info!(target: "validator::purge_pending_txs", "No erroneous transactions found");
return Ok(())
}
info!(target: "validator::purge_pending_txs", "Removing {} erroneous transactions...", removed_txs.len());
self.blockchain.remove_pending_txs(&removed_txs)?;
Ok(())
}
/// The node locks its consensus state and tries to append provided proposal.
pub async fn append_proposal(&self, proposal: &Proposal) -> Result<()> {
// Grab append lock so we restrict concurrent calls of this function
let append_lock = self.consensus.append_lock.write().await;
// Execute append
let result = self.consensus.append_proposal(proposal, self.verify_fees).await;
// Release append lock
drop(append_lock);
result
}
/// The node checks if best fork can be finalized.
/// If proposals can be finalized, node appends them to canonical,
/// and resets the current forks.
pub async fn finalization(&self) -> Result<Vec<BlockInfo>> {
// Grab append lock so no new proposals can be appended while
// we execute finalization
let append_lock = self.consensus.append_lock.write().await;
info!(target: "validator::finalization", "Performing finalization check");
// Grab best fork index that can be finalized
let finalized_fork = match self.consensus.finalization().await {
Ok(f) => f,
Err(e) => {
drop(append_lock);
return Err(e)
}
};
if finalized_fork.is_none() {
info!(target: "validator::finalization", "No proposals can be finalized");
drop(append_lock);
return Ok(vec![])
}
// Grab the actual best fork
let finalized_fork = finalized_fork.unwrap();
let mut forks = self.consensus.forks.write().await;
let fork = &mut forks[finalized_fork];
// Find the excess over finalization threshold
let excess = (fork.proposals.len() - self.consensus.finalization_threshold) + 1;
// Grab finalized proposals and update fork's sequences
let rest_proposals = fork.proposals.split_off(excess);
let rest_diffs = fork.diffs.split_off(excess);
let finalized_proposals = fork.proposals.clone();
let mut diffs = fork.diffs.clone();
fork.proposals = rest_proposals;
fork.diffs = rest_diffs;
// Grab finalized proposals blocks
let finalized_blocks =
fork.overlay.lock().unwrap().get_blocks_by_hash(&finalized_proposals)?;
// Apply finalized proposals diffs and update PoW module
let mut module = self.consensus.module.write().await;
let mut finalized_txs = vec![];
info!(target: "validator::finalization", "Finalizing proposals:");
for (index, proposal) in finalized_proposals.iter().enumerate() {
info!(target: "validator::finalization", "\t{} - {}", proposal, finalized_blocks[index].header.height);
fork.overlay.lock().unwrap().overlay.lock().unwrap().apply_diff(&mut diffs[index])?;
let next_difficulty = module.next_difficulty()?;
module.append(finalized_blocks[index].header.timestamp, &next_difficulty);
finalized_txs.extend_from_slice(&finalized_blocks[index].txs);
}
drop(module);
drop(forks);
// Reset forks starting with the finalized blocks
self.consensus.reset_forks(&finalized_proposals, &finalized_fork, &finalized_txs).await?;
info!(target: "validator::finalization", "Finalization completed!");
// Release append lock
drop(append_lock);
Ok(finalized_blocks)
}
/// Apply provided set of [`BlockInfo`] without doing formal verification.
/// A set of ['HeaderHash`] is also provided, to verify that the provided
/// block hash matches the expected header one.
/// Note: this function should only be used for blocks received using a
/// checkpoint, since in that case we enforce the node to follow the sequence,
/// assuming they all its blocks are valid. Additionally, it will update
/// any forks to a single empty one, holding the updated module.
pub async fn add_checkpoint_blocks(
&self,
blocks: &[BlockInfo],
headers: &[HeaderHash],
) -> Result<()> {
// Check provided sequences are the same length
if blocks.len() != headers.len() {
return Err(Error::InvalidInputLengths)
}
debug!(target: "validator::add_checkpoint_blocks", "Instantiating BlockchainOverlay");
let overlay = BlockchainOverlay::new(&self.blockchain)?;
// Retrieve last block difficulty to access current ranks
let last_difficulty = self.blockchain.last_block_difficulty()?;
let mut current_targets_rank = last_difficulty.ranks.targets_rank;
let mut current_hashes_rank = last_difficulty.ranks.hashes_rank;
// Grab current PoW module to validate each block
let mut module = self.consensus.module.read().await.clone();
// Keep track of all blocks transactions to remove them from pending txs store
let mut removed_txs = vec![];
// Validate and insert each block
for (index, block) in blocks.iter().enumerate() {
// Verify block
match verify_checkpoint_block(&overlay, block, &headers[index], module.target).await {
Ok(()) => { /* Do nothing */ }
// Skip already existing block
Err(Error::BlockAlreadyExists(_)) => continue,
Err(e) => {
error!(target: "validator::add_checkpoint_blocks", "Erroneous block found in set: {}", e);
overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
return Err(Error::BlockIsInvalid(block.hash().as_string()))
}
};
// Grab next mine target and difficulty
let (next_target, next_difficulty) = module.next_mine_target_and_difficulty()?;
// Calculate block rank
let (target_distance_sq, hash_distance_sq) = block_rank(block, &next_target);
// Update current ranks
current_targets_rank += target_distance_sq.clone();
current_hashes_rank += hash_distance_sq.clone();
// Generate block difficulty and update PoW module
let cummulative_difficulty =
module.cummulative_difficulty.clone() + next_difficulty.clone();
let ranks = BlockRanks::new(
target_distance_sq,
current_targets_rank.clone(),
hash_distance_sq,
current_hashes_rank.clone(),
);
let block_difficulty = BlockDifficulty::new(
block.header.height,
block.header.timestamp,
next_difficulty,
cummulative_difficulty,
ranks,
);
module.append_difficulty(&overlay, block_difficulty)?;
// Store block transactions
for tx in &block.txs {
removed_txs.push(tx.clone());
}
}
debug!(target: "validator::add_checkpoint_blocks", "Applying overlay changes");
overlay.lock().unwrap().overlay.lock().unwrap().apply()?;
// Remove blocks transactions from pending txs store
self.blockchain.remove_pending_txs(&removed_txs)?;
// Update PoW module
*self.consensus.module.write().await = module.clone();
// Update forks
*self.consensus.forks.write().await =
vec![Fork::new(self.blockchain.clone(), module).await?];
Ok(())
}
/// Validate a set of [`BlockInfo`] in sequence and apply them if all are valid.
/// Note: this function should only be used in tests when we don't want to
/// perform consensus logic.
pub async fn add_test_blocks(&self, blocks: &[BlockInfo]) -> Result<()> {
debug!(target: "validator::add_test_blocks", "Instantiating BlockchainOverlay");
let overlay = BlockchainOverlay::new(&self.blockchain)?;
// Retrieve last block
let mut previous = &overlay.lock().unwrap().last_block()?;
// Retrieve last block difficulty to access current ranks
let last_difficulty = self.blockchain.last_block_difficulty()?;
let mut current_targets_rank = last_difficulty.ranks.targets_rank;
let mut current_hashes_rank = last_difficulty.ranks.hashes_rank;
// Grab current PoW module to validate each block
let mut module = self.consensus.module.read().await.clone();
// Keep track of all blocks transactions to remove them from pending txs store
let mut removed_txs = vec![];
// Validate and insert each block
for block in blocks {
// Verify block
match verify_block(&overlay, &module, block, previous, self.verify_fees).await {
Ok(()) => { /* Do nothing */ }
// Skip already existing block
Err(Error::BlockAlreadyExists(_)) => {
previous = block;
continue
}
Err(e) => {
error!(target: "validator::add_test_blocks", "Erroneous block found in set: {}", e);
overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
return Err(Error::BlockIsInvalid(block.hash().as_string()))
}
};
// Grab next mine target and difficulty
let (next_target, next_difficulty) = module.next_mine_target_and_difficulty()?;
// Calculate block rank
let (target_distance_sq, hash_distance_sq) = block_rank(block, &next_target);
// Update current ranks
current_targets_rank += target_distance_sq.clone();
current_hashes_rank += hash_distance_sq.clone();
// Generate block difficulty and update PoW module
let cummulative_difficulty =
module.cummulative_difficulty.clone() + next_difficulty.clone();
let ranks = BlockRanks::new(
target_distance_sq,
current_targets_rank.clone(),
hash_distance_sq,
current_hashes_rank.clone(),
);
let block_difficulty = BlockDifficulty::new(
block.header.height,
block.header.timestamp,
next_difficulty,
cummulative_difficulty,
ranks,
);
module.append_difficulty(&overlay, block_difficulty)?;
// Store block transactions
for tx in &block.txs {
removed_txs.push(tx.clone());
}
// Use last inserted block as next iteration previous
previous = block;
}
debug!(target: "validator::add_test_blocks", "Applying overlay changes");
overlay.lock().unwrap().overlay.lock().unwrap().apply()?;
// Purge pending erroneous txs since canonical state has been changed
self.blockchain.remove_pending_txs(&removed_txs)?;
self.purge_pending_txs().await?;
// Update PoW module
*self.consensus.module.write().await = module;
Ok(())
}
/// Validate a set of [`Transaction`] in sequence and apply them if all are valid.
/// In case any of the transactions fail, they will be returned to the caller.
/// The function takes a boolean called `write` which tells it to actually write
/// the state transitions to the database, and a boolean called `verify_fees` to
/// overwrite the nodes configured `verify_fees` flag.
///
/// Returns the total gas used and total paid fees for the given transactions.
/// Note: this function should only be used in tests.
pub async fn add_test_transactions(
&self,
txs: &[Transaction],
verifying_block_height: u32,
block_target: u32,
write: bool,
verify_fees: bool,
) -> Result<(u64, u64)> {
debug!(target: "validator::add_transactions", "Instantiating BlockchainOverlay");
let overlay = BlockchainOverlay::new(&self.blockchain)?;
// Verify all transactions and get erroneous ones
let verify_result = verify_transactions(
&overlay,
verifying_block_height,
block_target,
txs,
&mut MerkleTree::new(1),
verify_fees,
)
.await;
let lock = overlay.lock().unwrap();
let mut overlay = lock.overlay.lock().unwrap();
if let Err(e) = verify_result {
overlay.purge_new_trees()?;
return Err(e)
}
let gas_values = verify_result.unwrap();
if !write {
debug!(target: "validator::add_transactions", "Skipping apply of state updates because write=false");
overlay.purge_new_trees()?;
return Ok(gas_values)
}
debug!(target: "validator::add_transactions", "Applying overlay changes");
overlay.apply()?;
Ok(gas_values)
}
/// Validate a producer `Transaction` and apply it if valid.
/// In case the transactions fail, ir will be returned to the caller.
/// The function takes a boolean called `write` which tells it to actually write
/// the state transitions to the database.
/// This should be only used for test purposes.
pub async fn add_test_producer_transaction(
&self,
tx: &Transaction,
verifying_block_height: u32,
block_target: u32,
write: bool,
) -> Result<()> {
debug!(target: "validator::add_test_producer_transaction", "Instantiating BlockchainOverlay");
let overlay = BlockchainOverlay::new(&self.blockchain)?;
// Verify transaction
let mut erroneous_txs = vec![];
if let Err(e) = verify_producer_transaction(
&overlay,
verifying_block_height,
block_target,
tx,
&mut MerkleTree::new(1),
)
.await
{
warn!(target: "validator::add_test_producer_transaction", "Transaction verification failed: {}", e);
erroneous_txs.push(tx.clone());
}
let lock = overlay.lock().unwrap();
let mut overlay = lock.overlay.lock().unwrap();
if !erroneous_txs.is_empty() {
warn!(target: "validator::add_test_producer_transaction", "Erroneous transactions found in set");
overlay.purge_new_trees()?;
return Err(TxVerifyFailed::ErroneousTxs(erroneous_txs).into())
}
if !write {
debug!(target: "validator::add_test_producer_transaction", "Skipping apply of state updates because write=false");
overlay.purge_new_trees()?;
return Ok(())
}
debug!(target: "validator::add_test_producer_transaction", "Applying overlay changes");
overlay.apply()?;
Ok(())
}
/// Retrieve all existing blocks and try to apply them
/// to an in memory overlay to verify their correctness.
/// Be careful as this will try to load everything in memory.
pub async fn validate_blockchain(
&self,
pow_target: u32,
pow_fixed_difficulty: Option<BigUint>,
) -> Result<()> {
let blocks = self.blockchain.get_all()?;
// An empty blockchain is considered valid
if blocks.is_empty() {
return Ok(())
}
// Create an in memory blockchain overlay
let sled_db = sled::Config::new().temporary(true).open()?;
let blockchain = Blockchain::new(&sled_db)?;
let overlay = BlockchainOverlay::new(&blockchain)?;
// Set previous
let mut previous = &blocks[0];
// Deploy native wasm contracts
deploy_native_contracts(&overlay, pow_target).await?;
// Validate genesis block
verify_genesis_block(&overlay, previous, pow_target).await?;
// Write the changes to the in memory db
overlay.lock().unwrap().overlay.lock().unwrap().apply()?;
// Create a PoW module to validate each block
let mut module = PoWModule::new(blockchain, pow_target, pow_fixed_difficulty)?;
// Validate and insert each block
for block in &blocks[1..] {
// Verify block
if verify_block(&overlay, &module, block, previous, self.verify_fees).await.is_err() {
error!(target: "validator::validate_blockchain", "Erroneous block found in set");
overlay.lock().unwrap().overlay.lock().unwrap().purge_new_trees()?;
return Err(Error::BlockIsInvalid(block.hash().as_string()))
};
// Update PoW module
module.append(block.header.timestamp, &module.next_difficulty()?);
// Use last inserted block as next iteration previous
previous = block;
}
Ok(())
}
/// Auxiliary function to retrieve current best fork next block height.
pub async fn best_fork_next_block_height(&self) -> Result<u32> {
let forks = self.consensus.forks.read().await;
let fork = &forks[best_fork_index(&forks)?];
let next_block_height = fork.get_next_block_height()?;
drop(forks);
Ok(next_block_height)
}
}