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chain_verifier.rs
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chain_verifier.rs
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//! Bitcoin chain verifier
use std::collections::BTreeSet;
use db::{self, BlockLocation, PreviousTransactionOutputProvider};
use network::{Magic, ConsensusParams};
use script::Script;
use super::{Verify, VerificationResult, Chain, Error, TransactionError};
use {chain, utils};
use scoped_pool::Pool;
const BLOCK_MAX_FUTURE: i64 = 2 * 60 * 60; // 2 hours
const COINBASE_MATURITY: u32 = 100; // 2 hours
const MAX_BLOCK_SIGOPS: usize = 20000;
const MAX_BLOCK_SIZE: usize = 1000000;
const TRANSACTIONS_VERIFY_THREADS: usize = 4;
const TRANSACTIONS_VERIFY_PARALLEL_THRESHOLD: usize = 16;
pub struct ChainVerifier {
store: db::SharedStore,
skip_pow: bool,
skip_sig: bool,
network: Magic,
consensus_params: ConsensusParams,
pool: Pool,
}
impl ChainVerifier {
pub fn new(store: db::SharedStore, network: Magic) -> Self {
ChainVerifier {
store: store,
skip_pow: false,
skip_sig: false,
network: network,
consensus_params: network.consensus_params(),
pool: Pool::new(TRANSACTIONS_VERIFY_THREADS),
}
}
#[cfg(test)]
pub fn pow_skip(mut self) -> Self {
self.skip_pow = true;
self
}
#[cfg(test)]
pub fn signatures_skip(mut self) -> Self {
self.skip_sig = true;
self
}
pub fn verify_p2sh(&self, time: u32) -> bool {
time >= self.consensus_params.bip16_time
}
pub fn verify_clocktimeverify(&self, height: u32) -> bool {
height >= self.consensus_params.bip65_height
}
/// Returns previous transaction output.
/// NOTE: This function expects all previous blocks to be already in database.
fn previous_transaction_output<T>(&self, prevout_provider: &T, prevout: &chain::OutPoint) -> Option<chain::TransactionOutput>
where T: PreviousTransactionOutputProvider {
self.store.transaction(&prevout.hash)
.and_then(|tx| tx.outputs.into_iter().nth(prevout.index as usize))
.or_else(|| prevout_provider.previous_transaction_output(prevout))
}
/// Returns number of transaction signature operations.
/// NOTE: This function expects all previous blocks to be already in database.
fn transaction_sigops(&self, block: &db::IndexedBlock, transaction: &chain::Transaction, bip16_active: bool) -> usize {
let output_sigops: usize = transaction.outputs.iter().map(|output| {
let output_script: Script = output.script_pubkey.clone().into();
output_script.sigops_count(false)
}).sum();
if transaction.is_coinbase() {
return output_sigops;
}
let input_sigops: usize = transaction.inputs.iter().map(|input| {
let input_script: Script = input.script_sig.clone().into();
let mut sigops = input_script.sigops_count(false);
if bip16_active {
let previous_output = self.previous_transaction_output(block, &input.previous_output)
.expect("missing tx, out of order verification or malformed db");
let prevout_script: Script = previous_output.script_pubkey.into();
sigops += input_script.pay_to_script_hash_sigops(&prevout_script);
}
sigops
}).sum();
input_sigops + output_sigops
}
/// Returns number of block signature operations.
/// NOTE: This function expects all previous blocks to be already in database.
fn block_sigops(&self, block: &db::IndexedBlock) -> usize {
// strict pay-to-script-hash signature operations count toward block
// signature operations limit is enforced with BIP16
let bip16_active = self.verify_p2sh(block.header().time);
block.transactions().map(|(_, tx)| self.transaction_sigops(block, tx, bip16_active)).sum()
}
fn ordered_verify(&self, block: &db::IndexedBlock, at_height: u32) -> Result<(), Error> {
if !block.is_final(at_height) {
return Err(Error::NonFinalBlock);
}
// transaction verification including number of signature operations checking
if self.block_sigops(block) > MAX_BLOCK_SIGOPS {
return Err(Error::MaximumSigops);
}
let block_hash = block.hash();
// check that difficulty matches the adjusted level
if let Some(work) = self.work_required(block, at_height) {
if !self.skip_pow && work != block.header().nbits {
trace!(target: "verification", "pow verification error at height: {}", at_height);
trace!(target: "verification", "expected work: {}, got {}", work, block.header().nbits);
return Err(Error::Difficulty);
}
}
let coinbase_spends = block.transactions()
.nth(0)
.expect("block emptyness should be checked at this point")
.1
.total_spends();
// bip30
for (tx_index, (tx_hash, _)) in block.transactions().enumerate() {
if let Some(meta) = self.store.transaction_meta(tx_hash) {
if !meta.is_fully_spent() && !self.consensus_params.is_bip30_exception(&block_hash, at_height) {
return Err(Error::Transaction(tx_index, TransactionError::UnspentTransactionWithTheSameHash));
}
}
}
let mut total_unspent = 0u64;
for (tx_index, (_, tx)) in block.transactions().enumerate().skip(1) {
let mut total_claimed: u64 = 0;
for input in &tx.inputs {
// Coinbase maturity check
if let Some(previous_meta) = self.store.transaction_meta(&input.previous_output.hash) {
// check if it exists only
// it will fail a little later if there is no transaction at all
if previous_meta.is_coinbase() &&
(at_height < COINBASE_MATURITY || at_height - COINBASE_MATURITY < previous_meta.height()) {
return Err(Error::Transaction(tx_index, TransactionError::Maturity));
}
}
let previous_output = self.previous_transaction_output(block, &input.previous_output)
.expect("missing tx, out of order verification or malformed db");
total_claimed += previous_output.value;
}
let total_spends = tx.total_spends();
if total_claimed < total_spends {
return Err(Error::Transaction(tx_index, TransactionError::Overspend));
}
// total_claimed is greater than total_spends, checked above and returned otherwise, cannot overflow; qed
total_unspent += total_claimed - total_spends;
}
let expected_max = utils::block_reward_satoshi(at_height) + total_unspent;
if coinbase_spends > expected_max{
return Err(Error::CoinbaseOverspend { expected_max: expected_max, actual: coinbase_spends });
}
Ok(())
}
pub fn verify_transaction<T>(
&self,
prevout_provider: &T,
height: u32,
time: u32,
transaction: &chain::Transaction,
sequence: usize
) -> Result<(), TransactionError> where T: PreviousTransactionOutputProvider {
use script::{
TransactionInputSigner,
TransactionSignatureChecker,
VerificationFlags,
Script,
verify_script,
};
if sequence == 0 {
return Ok(());
}
// must not be coinbase (sequence = 0 is returned above)
if transaction.is_coinbase() { return Err(TransactionError::MisplacedCoinbase(sequence)); }
for (input_index, input) in transaction.inputs().iter().enumerate() {
// signature verification
let signer: TransactionInputSigner = transaction.clone().into();
let paired_output = match self.previous_transaction_output(prevout_provider, &input.previous_output) {
Some(output) => output,
_ => return Err(TransactionError::UnknownReference(input.previous_output.hash.clone()))
};
let checker = TransactionSignatureChecker {
signer: signer,
input_index: input_index,
};
let input: Script = input.script_sig.clone().into();
let output: Script = paired_output.script_pubkey.into();
let flags = VerificationFlags::default()
.verify_p2sh(self.verify_p2sh(time))
.verify_clocktimeverify(self.verify_clocktimeverify(height));
// for tests only, skips as late as possible
if self.skip_sig { continue; }
if let Err(e) = verify_script(&input, &output, &flags, &checker) {
trace!(target: "verification", "transaction signature verification failure: {:?}", e);
trace!(target: "verification", "input:\n{}", input);
trace!(target: "verification", "output:\n{}", output);
// todo: log error here
return Err(TransactionError::Signature(input_index))
}
}
Ok(())
}
fn verify_block(&self, block: &db::IndexedBlock) -> VerificationResult {
use task::Task;
let hash = block.hash();
// There should be at least 1 transaction
if block.transaction_count() == 0 {
return Err(Error::Empty);
}
// target difficulty threshold
if !self.skip_pow && !utils::check_nbits(self.network.max_nbits(), &hash, block.header().nbits) {
return Err(Error::Pow);
}
// check if block timestamp is not far in the future
if utils::age(block.header().time) < -BLOCK_MAX_FUTURE {
return Err(Error::Timestamp);
}
if let Some(median_timestamp) = self.median_timestamp(block) {
if median_timestamp >= block.header().time {
trace!(
target: "verification", "median timestamp verification failed, median: {}, current: {}",
median_timestamp,
block.header().time
);
return Err(Error::Timestamp);
}
}
// todo: serialized_size function is at least suboptimal
let size = block.size();
if size > MAX_BLOCK_SIZE {
return Err(Error::Size(size))
}
// verify merkle root
if block.merkle_root() != block.header().merkle_root_hash {
return Err(Error::MerkleRoot);
}
let first_tx = block.transactions().nth(0).expect("transaction count is checked above to be greater than 0").1;
// check first transaction is a coinbase transaction
if !first_tx.is_coinbase() {
return Err(Error::Coinbase)
}
// check that coinbase has a valid signature
// is_coinbase() = true above guarantees that there is at least one input
let coinbase_script_len = first_tx.inputs[0].script_sig.len();
if coinbase_script_len < 2 || coinbase_script_len > 100 {
return Err(Error::CoinbaseSignatureLength(coinbase_script_len));
}
let location = match self.store.accepted_location(block.header()) {
Some(location) => location,
None => return Ok(Chain::Orphan),
};
if block.transaction_count() > TRANSACTIONS_VERIFY_PARALLEL_THRESHOLD {
// todo: might use on-stack vector (smallvec/elastic array)
let mut transaction_tasks: Vec<Task> = Vec::with_capacity(TRANSACTIONS_VERIFY_THREADS);
let mut last = 0;
for num_task in 0..TRANSACTIONS_VERIFY_THREADS {
let from = last;
last = ::std::cmp::max(1, block.transaction_count() / TRANSACTIONS_VERIFY_THREADS);
if num_task == TRANSACTIONS_VERIFY_THREADS - 1 { last = block.transaction_count(); };
transaction_tasks.push(Task::new(block, location.height(), from, last));
}
self.pool.scoped(|scope| {
for task in transaction_tasks.iter_mut() {
scope.execute(move || task.progress(self))
}
});
for task in transaction_tasks.into_iter() {
if let Err((index, tx_err)) = task.result() {
return Err(Error::Transaction(index, tx_err));
}
}
}
else {
for (index, (_, tx)) in block.transactions().enumerate() {
if let Err(tx_err) = self.verify_transaction(block, location.height(), block.header().time, tx, index) {
return Err(Error::Transaction(index, tx_err));
}
}
}
// todo: pre-process projected block number once verification is parallel!
match location {
BlockLocation::Main(block_number) => {
try!(self.ordered_verify(block, block_number));
Ok(Chain::Main)
},
BlockLocation::Side(block_number) => {
try!(self.ordered_verify(block, block_number));
Ok(Chain::Side)
},
}
}
fn median_timestamp(&self, block: &db::IndexedBlock) -> Option<u32> {
let mut timestamps = BTreeSet::new();
let mut block_ref = block.header().previous_header_hash.clone().into();
// TODO: optimize it, so it does not make 11 redundant queries each time
for _ in 0..11 {
let previous_header = match self.store.block_header(block_ref) {
Some(h) => h,
None => { break; }
};
timestamps.insert(previous_header.time);
block_ref = previous_header.previous_header_hash.into();
}
if timestamps.len() > 2 {
let timestamps: Vec<_> = timestamps.into_iter().collect();
Some(timestamps[timestamps.len() / 2])
}
else { None }
}
fn work_required(&self, block: &db::IndexedBlock, height: u32) -> Option<u32> {
if height == 0 {
return None;
}
let previous_ref = block.header().previous_header_hash.clone().into();
let previous_header = self.store.block_header(previous_ref).expect("self.height != 0; qed");
if utils::is_retarget_height(height) {
let retarget_ref = (height - utils::RETARGETING_INTERVAL).into();
let retarget_header = self.store.block_header(retarget_ref).expect("self.height != 0 && self.height % RETARGETING_INTERVAL == 0; qed");
// timestamp of block(height - RETARGETING_INTERVAL)
let retarget_timestamp = retarget_header.time;
// timestamp of parent block
let last_timestamp = previous_header.time;
// nbits of last block
let last_nbits = previous_header.nbits;
return Some(utils::work_required_retarget(self.network.max_nbits(), retarget_timestamp, last_timestamp, last_nbits));
}
// TODO: if.testnet
Some(previous_header.nbits)
}
}
impl Verify for ChainVerifier {
fn verify(&self, block: &db::IndexedBlock) -> VerificationResult {
let result = self.verify_block(block);
trace!(
target: "verification", "Block {} (transactions: {}) verification finished. Result {:?}",
block.hash().to_reversed_str(),
block.transaction_count(),
result,
);
result
}
}
#[cfg(test)]
mod tests {
use std::sync::Arc;
use db::{TestStorage, Storage, Store, BlockStapler, IndexedBlock};
use network::Magic;
use devtools::RandomTempPath;
use {script, test_data};
use super::ChainVerifier;
use super::super::{Verify, Chain, Error, TransactionError};
#[test]
fn verify_orphan() {
let storage = TestStorage::with_blocks(&vec![test_data::genesis()]);
let b2 = test_data::block_h2();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet);
assert_eq!(Chain::Orphan, verifier.verify(&b2.into()).unwrap());
}
#[test]
fn verify_smoky() {
let storage = TestStorage::with_blocks(&vec![test_data::genesis()]);
let b1 = test_data::block_h1();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet);
assert_eq!(Chain::Main, verifier.verify(&b1.into()).unwrap());
}
#[test]
fn firtst_tx() {
let storage = TestStorage::with_blocks(
&vec![
test_data::block_h9(),
test_data::block_h169(),
]
);
let b1 = test_data::block_h170();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet);
assert_eq!(Chain::Main, verifier.verify(&b1.into()).unwrap());
}
#[test]
fn coinbase_maturity() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).unwrap();
let genesis_coinbase = genesis.transactions()[0].hash();
let block = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input().hash(genesis_coinbase).build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Err(Error::Transaction(
1,
TransactionError::Maturity,
));
assert_eq!(expected, verifier.verify(&block.into()));
}
#[test]
fn non_coinbase_happy() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.output().value(1).build()
.build()
.transaction()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).unwrap();
let reference_tx = genesis.transactions()[1].hash();
let block = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input().hash(reference_tx).build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Ok(Chain::Main);
assert_eq!(expected, verifier.verify(&block.into()));
}
#[test]
fn transaction_references_same_block_happy() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.output().value(1).build()
.build()
.transaction()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).expect("Genesis should be inserted with no errors");
let genesis_coinbase = genesis.transactions()[1].hash();
let block = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input().hash(genesis_coinbase).build()
.output().value(30).build()
.output().value(20).build()
.build()
.derived_transaction(1, 0)
.output().value(30).build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Ok(Chain::Main);
assert_eq!(expected, verifier.verify(&block.into()));
}
#[test]
fn transaction_references_same_block_overspend() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.output().value(1).build()
.build()
.transaction()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).expect("Genesis should be inserted with no errors");
let genesis_coinbase = genesis.transactions()[1].hash();
let block = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input().hash(genesis_coinbase).build()
.output().value(30).build()
.output().value(20).build()
.build()
.derived_transaction(1, 0)
.output().value(35).build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Err(Error::Transaction(2, TransactionError::Overspend));
assert_eq!(expected, verifier.verify(&block.into()));
}
#[test]
#[ignore]
fn coinbase_happy() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).unwrap();
let genesis_coinbase = genesis.transactions()[0].hash();
// waiting 100 blocks for genesis coinbase to become valid
for _ in 0..100 {
storage.insert_block(
&test_data::block_builder()
.transaction().coinbase().build()
.merkled_header().parent(genesis.hash()).build()
.build()
).expect("All dummy blocks should be inserted");
}
let best_hash = storage.best_block().expect("Store should have hash after all we pushed there").hash;
let block = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input().hash(genesis_coinbase.clone()).build()
.build()
.merkled_header().parent(best_hash).build()
.build();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Ok(Chain::Main);
assert_eq!(expected, verifier.verify(&block.into()))
}
#[test]
fn sigops_overflow_block() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction()
.coinbase()
.build()
.transaction()
.output().value(50).build()
.build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).unwrap();
let reference_tx = genesis.transactions()[1].hash();
let mut builder_tx1 = script::Builder::default();
for _ in 0..11000 {
builder_tx1 = builder_tx1.push_opcode(script::Opcode::OP_CHECKSIG)
}
let mut builder_tx2 = script::Builder::default();
for _ in 0..11000 {
builder_tx2 = builder_tx2.push_opcode(script::Opcode::OP_CHECKSIG)
}
let block: IndexedBlock = test_data::block_builder()
.transaction().coinbase().build()
.transaction()
.input()
.hash(reference_tx.clone())
.signature_bytes(builder_tx1.into_script().to_bytes())
.build()
.build()
.transaction()
.input()
.hash(reference_tx)
.signature_bytes(builder_tx2.into_script().to_bytes())
.build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build()
.into();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Err(Error::MaximumSigops);
assert_eq!(expected, verifier.verify(&block.into()));
}
#[test]
fn coinbase_overspend() {
let path = RandomTempPath::create_dir();
let storage = Storage::new(path.as_path()).unwrap();
let genesis = test_data::block_builder()
.transaction().coinbase().build()
.merkled_header().build()
.build();
storage.insert_block(&genesis).unwrap();
let block: IndexedBlock = test_data::block_builder()
.transaction()
.coinbase()
.output().value(5000000001).build()
.build()
.merkled_header().parent(genesis.hash()).build()
.build()
.into();
let verifier = ChainVerifier::new(Arc::new(storage), Magic::Testnet).pow_skip().signatures_skip();
let expected = Err(Error::CoinbaseOverspend {
expected_max: 5000000000,
actual: 5000000001
});
assert_eq!(expected, verifier.verify(&block.into()));
}
}