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Add transactions that failed verification to the mempool rejected list (#2821) 

* Add transactions that failed verification to the mempool rejected list

* Add tests

* Work with recent changes
This commit is contained in:
Conrado Gouvea 2021-10-07 18:34:01 -03:00 committed by GitHub
parent 664d4384d4
commit dd1f0a6dcc
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5 changed files with 332 additions and 23 deletions
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54
zebrad/src/components/mempool.rs
View File

@ -41,7 +41,8 @@ pub use self::storage::{
pub use self::storage::tests::unmined_transactions_in_blocks;
use self::downloads::{
Downloads as TxDownloads, Gossip, TRANSACTION_DOWNLOAD_TIMEOUT, TRANSACTION_VERIFY_TIMEOUT,
Downloads as TxDownloads, Gossip, TransactionDownloadVerifyError, TRANSACTION_DOWNLOAD_TIMEOUT,
TRANSACTION_VERIFY_TIMEOUT,
};
use super::sync::SyncStatus;
@ -227,11 +228,17 @@ impl Service<Request> for Mempool {
// Clean up completed download tasks and add to mempool if successful.
while let Poll::Ready(Some(r)) = tx_downloads.as_mut().poll_next(cx) {
if let Ok(tx) = r {
// Storage handles conflicting transactions or a full mempool internally,
// so just ignore the storage result here
let _ = storage.insert(tx);
}
match r {
Ok(tx) => {
// Storage handles conflicting transactions or a full mempool internally,
// so just ignore the storage result here
let _ = storage.insert(tx);
}
Err((txid, e)) => {
reject_if_needed(storage, txid, e);
// TODO: should we also log the result?
}
};
}
// Remove expired transactions from the mempool.
@ -327,3 +334,38 @@ fn remove_expired_transactions(
// expiry height is effecting data, so we match by non-malleable TXID
storage.remove_same_effects(&txid_set);
}
/// Add a transaction that failed download and verification to the rejected list
/// if needed, depending on the reason for the failure.
fn reject_if_needed(
storage: &mut storage::Storage,
txid: UnminedTxId,
e: TransactionDownloadVerifyError,
) {
match e {
// Rejecting a transaction already in state would speed up further
// download attempts without checking the state. However it would
// make the reject list grow forever.
// TODO: revisit after reviewing the rejected list cleanup criteria?
// TODO: if we decide to reject it, then we need to pass the block hash
// to State::Confirmed. This would require the zs::Response::Transaction
// to include the hash, which would need to be implemented.
TransactionDownloadVerifyError::InState |
// An unknown error in the state service, better do nothing
TransactionDownloadVerifyError::StateError(_) |
// Sync has just started. Mempool shouldn't even be enabled, so will not
// happen in practice.
TransactionDownloadVerifyError::NoTip |
// If download failed, do nothing; the crawler will end up trying to
// download it again.
TransactionDownloadVerifyError::DownloadFailed(_) |
// If it was cancelled then a block was mined, or there was a network
// upgrade, etc. No reason to reject it.
TransactionDownloadVerifyError::Cancelled => {}
// Consensus verification failed. Reject transaction to avoid
// having to download and verify it again just for it to fail again.
TransactionDownloadVerifyError::Invalid(e) => {
storage.reject(txid, ExactTipRejectionError::FailedVerification(e).into())
}
}
}

69
zebrad/src/components/mempool/downloads.rs
View File

@ -5,13 +5,13 @@ use std::{
time::Duration,
};
use color_eyre::eyre::eyre;
use futures::{
future::TryFutureExt,
ready,
stream::{FuturesUnordered, Stream},
};
use pin_project::pin_project;
use thiserror::Error;
use tokio::{sync::oneshot, task::JoinHandle};
use tower::{Service, ServiceExt};
use tracing_futures::Instrument;
@ -65,6 +65,29 @@ pub(crate) const TRANSACTION_VERIFY_TIMEOUT: Duration = BLOCK_VERIFY_TIMEOUT;
/// Therefore, this attack can be carried out by a single malicious node.
pub(crate) const MAX_INBOUND_CONCURRENCY: usize = 10;
/// Errors that can occur while downloading and verifying a transaction.
#[derive(Error, Debug)]
#[allow(dead_code)]
pub enum TransactionDownloadVerifyError {
#[error("transaction is already in state")]
InState,
#[error("error in state service")]
StateError(#[source] BoxError),
#[error("transaction not validated because the tip is empty")]
NoTip,
#[error("error downloading transaction")]
DownloadFailed(#[source] BoxError),
#[error("transaction download / verification was cancelled")]
Cancelled,
#[error("transaction did not pass consensus validation")]
Invalid(#[from] zebra_consensus::error::TransactionError),
}
/// A gossiped transaction, which can be the transaction itself or just its ID.
#[derive(Debug, Eq, PartialEq)]
pub enum Gossip {
@ -120,7 +143,9 @@ where
// Internal downloads state
/// A list of pending transaction download and verify tasks.
#[pin]
pending: FuturesUnordered<JoinHandle<Result<UnminedTx, (BoxError, UnminedTxId)>>>,
pending: FuturesUnordered<
JoinHandle<Result<UnminedTx, (TransactionDownloadVerifyError, UnminedTxId)>>,
>,
/// A list of channels that can be used to cancel pending transaction download and
/// verify tasks.
@ -136,7 +161,7 @@ where
ZS: Service<zs::Request, Response = zs::Response, Error = BoxError> + Send + Clone + 'static,
ZS::Future: Send,
{
type Item = Result<UnminedTx, BoxError>;
type Item = Result<UnminedTx, (UnminedTxId, TransactionDownloadVerifyError)>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
let this = self.project();
@ -157,7 +182,7 @@ where
}
Err((e, hash)) => {
this.cancel_handles.remove(&hash);
Poll::Ready(Some(Err(e)))
Poll::Ready(Some(Err((hash, e))))
}
}
} else {
@ -237,21 +262,27 @@ where
Self::transaction_in_state(&mut state, txid).await?;
let height = match state.oneshot(zs::Request::Tip).await {
Ok(zs::Response::Tip(None)) => Err("no block at the tip".into()),
Ok(zs::Response::Tip(None)) => Err(TransactionDownloadVerifyError::NoTip),
Ok(zs::Response::Tip(Some((height, _hash)))) => Ok(height),
Ok(_) => unreachable!("wrong response"),
Err(e) => Err(e),
Err(e) => Err(TransactionDownloadVerifyError::StateError(e)),
}?;
let height = (height + 1).ok_or_else(|| eyre!("no next height"))?;
let height = (height + 1).expect("must have next height");
let tx = match gossiped_tx {
Gossip::Id(txid) => {
let req = zn::Request::TransactionsById(std::iter::once(txid).collect());
let tx = match network.oneshot(req).await? {
zn::Response::Transactions(mut txs) => txs
.pop()
.expect("successful response has the transaction in it"),
let tx = match network
.oneshot(req)
.await
.map_err(|e| TransactionDownloadVerifyError::DownloadFailed(e))?
{
zn::Response::Transactions(mut txs) => txs.pop().ok_or_else(|| {
TransactionDownloadVerifyError::DownloadFailed(
"no transactions returned".into(),
)
})?,
_ => unreachable!("wrong response to transaction request"),
};
@ -274,7 +305,7 @@ where
tracing::debug!(?txid, ?result, "verified transaction for the mempool");
result
result.map_err(|e| TransactionDownloadVerifyError::Invalid(e.into()))
}
.map_ok(|tx| {
metrics::counter!("gossip.verified.transaction.count", 1);
@ -292,7 +323,7 @@ where
_ = &mut cancel_rx => {
tracing::trace!("task cancelled prior to completion");
metrics::counter!("gossip.cancelled.count", 1);
Err(("canceled".into(), txid))
Err((TransactionDownloadVerifyError::Cancelled, txid))
}
verification = fut => verification,
}
@ -357,18 +388,22 @@ where
}
/// Check if transaction is already in the state.
async fn transaction_in_state(state: &mut ZS, txid: UnminedTxId) -> Result<(), BoxError> {
async fn transaction_in_state(
state: &mut ZS,
txid: UnminedTxId,
) -> Result<(), TransactionDownloadVerifyError> {
// Check if the transaction is already in the state.
match state
.ready_and()
.await?
.await
.map_err(|e| TransactionDownloadVerifyError::StateError(e))?
.call(zs::Request::Transaction(txid.mined_id()))
.await
{
Ok(zs::Response::Transaction(None)) => Ok(()),
Ok(zs::Response::Transaction(Some(_))) => Err("already present in state".into()),
Ok(zs::Response::Transaction(Some(_))) => Err(TransactionDownloadVerifyError::InState),
Ok(_) => unreachable!("wrong response"),
Err(e) => Err(e),
Err(e) => Err(TransactionDownloadVerifyError::StateError(e)),
}?;
Ok(())

3
zebrad/src/components/mempool/error.rs
View File

@ -52,4 +52,7 @@ pub enum MempoolError {
#[error("mempool is disabled since synchronization is behind the chain tip")]
Disabled,
#[error("error calling a service")]
ServiceError,
}

28
zebrad/src/components/mempool/storage.rs
View File

@ -76,6 +76,18 @@ pub enum SameEffectsChainRejectionError {
RandomlyEvicted,
}
/// Storage error that combines all other specific error types.
#[derive(Error, Clone, Debug, PartialEq, Eq)]
#[allow(dead_code)]
pub enum RejectionError {
#[error(transparent)]
ExactTip(#[from] ExactTipRejectionError),
#[error(transparent)]
SameEffectsTip(#[from] SameEffectsTipRejectionError),
#[error(transparent)]
SameEffectsChain(#[from] SameEffectsChainRejectionError),
}
#[derive(Default)]
pub struct Storage {
/// The set of verified transactions in the mempool. This is a
@ -279,6 +291,22 @@ impl Storage {
+ self.chain_rejected_same_effects.len()
}
/// Add a transaction to the rejected list for the given reason.
pub fn reject(&mut self, txid: UnminedTxId, reason: RejectionError) {
match reason {
RejectionError::ExactTip(e) => {
self.tip_rejected_exact.insert(txid, e);
}
RejectionError::SameEffectsTip(e) => {
self.tip_rejected_same_effects.insert(txid.mined_id(), e);
}
RejectionError::SameEffectsChain(e) => {
self.chain_rejected_same_effects.insert(txid.mined_id(), e);
}
}
self.limit_rejection_list_memory();
}
/// Returns `true` if a [`UnminedTx`] matching an [`UnminedTxId`] is in
/// any mempool rejected list.
///

201
zebrad/src/components/mempool/tests/vector.rs
View File

@ -563,3 +563,204 @@ async fn mempool_cancel_downloads_after_network_upgrade() -> Result<(), Report>
Ok(())
}
/// Check if a transaction that fails verification is rejected by the mempool.
#[tokio::test]
async fn mempool_failed_verification_is_rejected() -> Result<(), Report> {
// Using the mainnet for now
let network = Network::Mainnet;
let consensus_config = ConsensusConfig::default();
let state_config = StateConfig::ephemeral();
let peer_set = MockService::build().for_unit_tests();
let (sync_status, mut recent_syncs) = SyncStatus::new();
let (state, latest_chain_tip, chain_tip_change) =
zebra_state::init(state_config.clone(), network);
let mut state_service = ServiceBuilder::new().buffer(1).service(state);
let (_chain_verifier, _tx_verifier) =
zebra_consensus::chain::init(consensus_config.clone(), network, state_service.clone())
.await;
let mut tx_verifier = MockService::build().for_unit_tests();
// Get transactions to use in the test
let mut unmined_transactions = unmined_transactions_in_blocks(1..=2, network);
let rejected_tx = unmined_transactions.next().unwrap().clone();
time::pause();
// Start the mempool service
let mut mempool = Mempool::new(
network,
Buffer::new(BoxService::new(peer_set.clone()), 1),
state_service.clone(),
Buffer::new(BoxService::new(tx_verifier.clone()), 1),
sync_status,
latest_chain_tip,
chain_tip_change,
);
// Enable the mempool
let _ = mempool.enable(&mut recent_syncs).await;
// Push the genesis block to the state, since downloader needs a valid tip.
let genesis_block: Arc<Block> = zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES
.zcash_deserialize_into()
.unwrap();
state_service
.ready_and()
.await
.unwrap()
.call(zebra_state::Request::CommitFinalizedBlock(
genesis_block.clone().into(),
))
.await
.unwrap();
// Queue first transaction for verification
// (queue the transaction itself to avoid a download).
let request = mempool
.ready_and()
.await
.unwrap()
.call(Request::Queue(vec![rejected_tx.clone().into()]));
// Make the mock verifier return that the transaction is invalid.
let verification = tx_verifier.expect_request_that(|_| true).map(|responder| {
responder.respond(Err(TransactionError::BadBalance));
});
let (response, _) = futures::join!(request, verification);
let queued_responses = match response.unwrap() {
Response::Queued(queue_responses) => queue_responses,
_ => unreachable!("will never happen in this test"),
};
// Check that the request was enqueued successfully.
assert_eq!(queued_responses.len(), 1);
assert!(queued_responses[0].is_ok());
for _ in 0..2 {
// Query the mempool just to poll it and make get the downloader/verifier result.
mempool.dummy_call().await;
// Sleep to avoid starvation and make sure the verification failure is picked up.
time::sleep(time::Duration::from_millis(100)).await;
}
// Try to queue the same transaction by its ID and check if it's correctly
// rejected.
let response = mempool
.ready_and()
.await
.unwrap()
.call(Request::Queue(vec![rejected_tx.id.into()]))
.await
.unwrap();
let queued_responses = match response {
Response::Queued(queue_responses) => queue_responses,
_ => unreachable!("will never happen in this test"),
};
assert_eq!(queued_responses.len(), 1);
assert!(matches!(
queued_responses[0],
Err(MempoolError::StorageExactTip(
ExactTipRejectionError::FailedVerification(_)
))
));
Ok(())
}
/// Check if a transaction that fails download is _not_ rejected.
#[tokio::test]
async fn mempool_failed_download_is_not_rejected() -> Result<(), Report> {
// Using the mainnet for now
let network = Network::Mainnet;
let consensus_config = ConsensusConfig::default();
let state_config = StateConfig::ephemeral();
let mut peer_set = MockService::build().for_unit_tests();
let (sync_status, mut recent_syncs) = SyncStatus::new();
let (state, latest_chain_tip, chain_tip_change) =
zebra_state::init(state_config.clone(), network);
let mut state_service = ServiceBuilder::new().buffer(1).service(state);
let (_chain_verifier, tx_verifier) =
zebra_consensus::chain::init(consensus_config.clone(), network, state_service.clone())
.await;
// Get transactions to use in the test
let mut unmined_transactions = unmined_transactions_in_blocks(1..=2, network);
let rejected_valid_tx = unmined_transactions.next().unwrap().clone();
time::pause();
// Start the mempool service
let mut mempool = Mempool::new(
network,
Buffer::new(BoxService::new(peer_set.clone()), 1),
state_service.clone(),
tx_verifier,
sync_status,
latest_chain_tip,
chain_tip_change,
);
// Enable the mempool
let _ = mempool.enable(&mut recent_syncs).await;
// Push the genesis block to the state, since downloader needs a valid tip.
let genesis_block: Arc<Block> = zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES
.zcash_deserialize_into()
.unwrap();
state_service
.ready_and()
.await
.unwrap()
.call(zebra_state::Request::CommitFinalizedBlock(
genesis_block.clone().into(),
))
.await
.unwrap();
// Queue second transaction for download and verification.
let request = mempool
.ready_and()
.await
.unwrap()
.call(Request::Queue(vec![rejected_valid_tx.id.into()]));
// Make the mock peer set return that the download failed.
let verification = peer_set
.expect_request_that(|r| matches!(r, zn::Request::TransactionsById(_)))
.map(|responder| {
responder.respond(zn::Response::Transactions(vec![]));
});
let (response, _) = futures::join!(request, verification);
let queued_responses = match response.unwrap() {
Response::Queued(queue_responses) => queue_responses,
_ => unreachable!("will never happen in this test"),
};
// Check that the request was enqueued successfully.
assert_eq!(queued_responses.len(), 1);
assert!(queued_responses[0].is_ok());
for _ in 0..2 {
// Query the mempool just to poll it and make get the downloader/verifier result.
mempool.dummy_call().await;
// Sleep to avoid starvation and make sure the download failure is picked up.
time::sleep(time::Duration::from_millis(100)).await;
}
// Try to queue the same transaction by its ID and check if it's not being
// rejected.
let response = mempool
.ready_and()
.await
.unwrap()
.call(Request::Queue(vec![rejected_valid_tx.id.into()]))
.await
.unwrap();
let queued_responses = match response {
Response::Queued(queue_responses) => queue_responses,
_ => unreachable!("will never happen in this test"),
};
assert_eq!(queued_responses.len(), 1);
assert!(queued_responses[0].is_ok());
Ok(())
}