Track block hash, return via get_relevant_txids

Previously, `Confirm::get_relevant_txids()` only returned a list of
transactions that have to be monitored for reorganization out of the
chain. This interface however required double bookkeeping: while we
internally keep track of the best block, height, etc, it would also
require the user to keep track which transaction was previously
confirmed in which block and to take actions based on any change, e.g,
to reconfirm them when the block would be reorged-out and the
transactions had been reconfirmed in another block.

Here, we track the confirmation block hash internally and return it via
`Confirm::get_relevant_txids()` to the user, which alleviates the
requirement for double bookkeeping: the user can now simply check
whether the given transaction is still confirmed and in the given block,
and take action if not.

Author: tnull

lightning/src/chain/chainmonitor.rs

@@ -24,7 +24,7 @@
 //! servicing [`ChannelMonitor`] updates from the client.
 
 use bitcoin::blockdata::block::BlockHeader;
-use bitcoin::hash_types::Txid;
+use bitcoin::hash_types::{Txid, BlockHash};
 
 use crate::chain;
 use crate::chain::{ChannelMonitorUpdateStatus, Filter, WatchedOutput};
@@ -544,7 +544,7 @@ where
 		});
 	}
 
-	fn get_relevant_txids(&self) -> Vec<Txid> {
+	fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)> {
 		let mut txids = Vec::new();
 		let monitor_states = self.monitors.read().unwrap();
 		for monitor_state in monitor_states.values() {

lightning/src/chain/channelmonitor.rs

@@ -332,14 +332,15 @@ impl Readable for CounterpartyCommitmentParameters {
 	}
 }
 
-/// An entry for an [`OnchainEvent`], stating the block height when the event was observed and the
-/// transaction causing it.
+/// An entry for an [`OnchainEvent`], stating the block height and hash when the event was
+/// observed, as well as the transaction causing it.
 ///
 /// Used to determine when the on-chain event can be considered safe from a chain reorganization.
 #[derive(PartialEq, Eq)]
 struct OnchainEventEntry {
 	txid: Txid,
 	height: u32,
+	block_hash: Option<BlockHash>, // Added as optional, will be filled in for any entry generated on 0.0.113 or after
 	event: OnchainEvent,
 	transaction: Option<Transaction>, // Added as optional, but always filled in, in LDK 0.0.110
 }
@@ -440,6 +441,7 @@ impl Writeable for OnchainEventEntry {
 			(0, self.txid, required),
 			(1, self.transaction, option),
 			(2, self.height, required),
+			(3, self.block_hash, option),
 			(4, self.event, required),
 		});
 		Ok(())
@@ -450,16 +452,18 @@ impl MaybeReadable for OnchainEventEntry {
 	fn read<R: io::Read>(reader: &mut R) -> Result<Option<Self>, DecodeError> {
 		let mut txid = Txid::all_zeros();
 		let mut transaction = None;
+		let mut block_hash = None;
 		let mut height = 0;
 		let mut event = None;
 		read_tlv_fields!(reader, {
 			(0, txid, required),
 			(1, transaction, option),
 			(2, height, required),
+			(3, block_hash, option),
 			(4, event, ignorable),
 		});
 		if let Some(ev) = event {
-			Ok(Some(Self { txid, transaction, height, event: ev }))
+			Ok(Some(Self { txid, transaction, height, block_hash, event: ev }))
 		} else {
 			Ok(None)
 		}
@@ -1482,11 +1486,11 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 	}
 
 	/// Returns the set of txids that should be monitored for re-organization out of the chain.
-	pub fn get_relevant_txids(&self) -> Vec<Txid> {
+	pub fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)> {
 		let inner = self.inner.lock().unwrap();
-		let mut txids: Vec<Txid> = inner.onchain_events_awaiting_threshold_conf
+		let mut txids: Vec<(Txid, Option<BlockHash>)> = inner.onchain_events_awaiting_threshold_conf
 			.iter()
-			.map(|entry| entry.txid)
+			.map(|entry| (entry.txid, entry.block_hash))
 			.chain(inner.onchain_tx_handler.get_relevant_txids().into_iter())
 			.collect();
 		txids.sort_unstable();
@@ -1939,7 +1943,7 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 /// been revoked yet, the previous one, we we will never "forget" to resolve an HTLC.
 macro_rules! fail_unbroadcast_htlcs {
 	($self: expr, $commitment_tx_type: expr, $commitment_txid_confirmed: expr, $commitment_tx_confirmed: expr,
-	 $commitment_tx_conf_height: expr, $confirmed_htlcs_list: expr, $logger: expr) => { {
+	 $commitment_tx_conf_height: expr, $commitment_tx_conf_hash: expr, $confirmed_htlcs_list: expr, $logger: expr) => { {
 		debug_assert_eq!($commitment_tx_confirmed.txid(), $commitment_txid_confirmed);
 
 		macro_rules! check_htlc_fails {
@@ -1983,6 +1987,7 @@ macro_rules! fail_unbroadcast_htlcs {
 								txid: $commitment_txid_confirmed,
 								transaction: Some($commitment_tx_confirmed.clone()),
 								height: $commitment_tx_conf_height,
+								block_hash: Some(*$commitment_tx_conf_hash),
 								event: OnchainEvent::HTLCUpdate {
 									source: (**source).clone(),
 									payment_hash: htlc.payment_hash.clone(),
@@ -2401,7 +2406,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 	/// Returns packages to claim the revoked output(s), as well as additional outputs to watch and
 	/// general information about the output that is to the counterparty in the commitment
 	/// transaction.
-	fn check_spend_counterparty_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L)
+	fn check_spend_counterparty_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, block_hash: &BlockHash, logger: &L)
 		-> (Vec<PackageTemplate>, TransactionOutputs, CommitmentTxCounterpartyOutputInfo)
 	where L::Target: Logger {
 		// Most secp and related errors trying to create keys means we have no hope of constructing
@@ -2472,13 +2477,13 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 				if let Some(per_commitment_data) = per_commitment_option {
 					fail_unbroadcast_htlcs!(self, "revoked_counterparty", commitment_txid, tx, height,
-						per_commitment_data.iter().map(|(htlc, htlc_source)|
+						block_hash, per_commitment_data.iter().map(|(htlc, htlc_source)|
 							(htlc, htlc_source.as_ref().map(|htlc_source| htlc_source.as_ref()))
 						), logger);
 				} else {
 					debug_assert!(false, "We should have per-commitment option for any recognized old commitment txn");
 					fail_unbroadcast_htlcs!(self, "revoked counterparty", commitment_txid, tx, height,
-						[].iter().map(|reference| *reference), logger);
+						block_hash, [].iter().map(|reference| *reference), logger);
 				}
 			}
 		} else if let Some(per_commitment_data) = per_commitment_option {
@@ -2495,7 +2500,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 			self.counterparty_commitment_txn_on_chain.insert(commitment_txid, commitment_number);
 
 			log_info!(logger, "Got broadcast of non-revoked counterparty commitment transaction {}", commitment_txid);
-			fail_unbroadcast_htlcs!(self, "counterparty", commitment_txid, tx, height,
+			fail_unbroadcast_htlcs!(self, "counterparty", commitment_txid, tx, height, block_hash,
 				per_commitment_data.iter().map(|(htlc, htlc_source)|
 					(htlc, htlc_source.as_ref().map(|htlc_source| htlc_source.as_ref()))
 				), logger);
@@ -2631,7 +2636,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		(claimable_outpoints, Some((htlc_txid, outputs)))
 	}
 
-	// Returns (1) `PackageTemplate`s that can be given to the OnChainTxHandler, so that the handler can
+	// Returns (1) `PackageTemplate`s that can be given to the OnchainTxHandler, so that the handler can
 	// broadcast transactions claiming holder HTLC commitment outputs and (2) a holder revokable
 	// script so we can detect whether a holder transaction has been seen on-chain.
 	fn get_broadcasted_holder_claims(&self, holder_tx: &HolderSignedTx, conf_height: u32) -> (Vec<PackageTemplate>, Option<(Script, PublicKey, PublicKey)>) {
@@ -2676,7 +2681,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 	/// revoked using data in holder_claimable_outpoints.
 	/// Should not be used if check_spend_revoked_transaction succeeds.
 	/// Returns None unless the transaction is definitely one of our commitment transactions.
-	fn check_spend_holder_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) -> Option<(Vec<PackageTemplate>, TransactionOutputs)> where L::Target: Logger {
+	fn check_spend_holder_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, block_hash: &BlockHash, logger: &L) -> Option<(Vec<PackageTemplate>, TransactionOutputs)> where L::Target: Logger {
 		let commitment_txid = tx.txid();
 		let mut claim_requests = Vec::new();
 		let mut watch_outputs = Vec::new();
@@ -2699,7 +2704,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 			let mut to_watch = self.get_broadcasted_holder_watch_outputs(&self.current_holder_commitment_tx, tx);
 			append_onchain_update!(res, to_watch);
 			fail_unbroadcast_htlcs!(self, "latest holder", commitment_txid, tx, height,
-				self.current_holder_commitment_tx.htlc_outputs.iter()
+				block_hash, self.current_holder_commitment_tx.htlc_outputs.iter()
 				.map(|(htlc, _, htlc_source)| (htlc, htlc_source.as_ref())), logger);
 		} else if let &Some(ref holder_tx) = &self.prev_holder_signed_commitment_tx {
 			if holder_tx.txid == commitment_txid {
@@ -2708,7 +2713,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				let res = self.get_broadcasted_holder_claims(holder_tx, height);
 				let mut to_watch = self.get_broadcasted_holder_watch_outputs(holder_tx, tx);
 				append_onchain_update!(res, to_watch);
-				fail_unbroadcast_htlcs!(self, "previous holder", commitment_txid, tx, height,
+				fail_unbroadcast_htlcs!(self, "previous holder", commitment_txid, tx, height, block_hash,
 					holder_tx.htlc_outputs.iter().map(|(htlc, _, htlc_source)| (htlc, htlc_source.as_ref())),
 					logger);
 			}
@@ -2816,7 +2821,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 		if height > self.best_block.height() {
 			self.best_block = BestBlock::new(block_hash, height);
-			self.block_confirmed(height, vec![], vec![], vec![], &broadcaster, &fee_estimator, &logger)
+			self.block_confirmed(height, block_hash, vec![], vec![], vec![], &broadcaster, &fee_estimator, &logger)
 		} else if block_hash != self.best_block.block_hash() {
 			self.best_block = BestBlock::new(block_hash, height);
 			self.onchain_events_awaiting_threshold_conf.retain(|ref entry| entry.height <= height);
@@ -2868,14 +2873,14 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 					let mut commitment_tx_to_counterparty_output = None;
 					if (tx.input[0].sequence.0 >> 8*3) as u8 == 0x80 && (tx.lock_time.0 >> 8*3) as u8 == 0x20 {
 						let (mut new_outpoints, new_outputs, counterparty_output_idx_sats) =
-							self.check_spend_counterparty_transaction(&tx, height, &logger);
+							self.check_spend_counterparty_transaction(&tx, height, &block_hash, &logger);
 						commitment_tx_to_counterparty_output = counterparty_output_idx_sats;
 						if !new_outputs.1.is_empty() {
 							watch_outputs.push(new_outputs);
 						}
 						claimable_outpoints.append(&mut new_outpoints);
 						if new_outpoints.is_empty() {
-							if let Some((mut new_outpoints, new_outputs)) = self.check_spend_holder_transaction(&tx, height, &logger) {
+							if let Some((mut new_outpoints, new_outputs)) = self.check_spend_holder_transaction(&tx, height, &block_hash, &logger) {
 								debug_assert!(commitment_tx_to_counterparty_output.is_none(),
 									"A commitment transaction matched as both a counterparty and local commitment tx?");
 								if !new_outputs.1.is_empty() {
@@ -2891,6 +2896,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 						txid,
 						transaction: Some((*tx).clone()),
 						height,
+						block_hash: Some(block_hash),
 						event: OnchainEvent::FundingSpendConfirmation {
 							on_local_output_csv: balance_spendable_csv,
 							commitment_tx_to_counterparty_output,
@@ -2909,16 +2915,16 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 			// While all commitment/HTLC-Success/HTLC-Timeout transactions have one input, HTLCs
 			// can also be resolved in a few other ways which can have more than one output. Thus,
 			// we call is_resolving_htlc_output here outside of the tx.input.len() == 1 check.
-			self.is_resolving_htlc_output(&tx, height, &logger);
+			self.is_resolving_htlc_output(&tx, height, &block_hash, &logger);
 
-			self.is_paying_spendable_output(&tx, height, &logger);
+			self.is_paying_spendable_output(&tx, height, &block_hash, &logger);
 		}
 
 		if height > self.best_block.height() {
 			self.best_block = BestBlock::new(block_hash, height);
 		}
 
-		self.block_confirmed(height, txn_matched, watch_outputs, claimable_outpoints, &broadcaster, &fee_estimator, &logger)
+		self.block_confirmed(height, block_hash, txn_matched, watch_outputs, claimable_outpoints, &broadcaster, &fee_estimator, &logger)
 	}
 
 	/// Update state for new block(s)/transaction(s) confirmed. Note that the caller must update
@@ -2931,6 +2937,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 	fn block_confirmed<B: Deref, F: Deref, L: Deref>(
 		&mut self,
 		conf_height: u32,
+		conf_hash: BlockHash,
 		txn_matched: Vec<&Transaction>,
 		mut watch_outputs: Vec<TransactionOutputs>,
 		mut claimable_outpoints: Vec<PackageTemplate>,
@@ -3235,7 +3242,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 	/// Check if any transaction broadcasted is resolving HTLC output by a success or timeout on a holder
 	/// or counterparty commitment tx, if so send back the source, preimage if found and payment_hash of resolved HTLC
-	fn is_resolving_htlc_output<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) where L::Target: Logger {
+	fn is_resolving_htlc_output<L: Deref>(&mut self, tx: &Transaction, height: u32, block_hash: &BlockHash, logger: &L) where L::Target: Logger {
 		'outer_loop: for input in &tx.input {
 			let mut payment_data = None;
 			let htlc_claim = HTLCClaim::from_witness(&input.witness);
@@ -3320,7 +3327,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 								log_claim!($tx_info, $holder_tx, htlc_output, false);
 								let outbound_htlc = $holder_tx == htlc_output.offered;
 								self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry {
-									txid: tx.txid(), height, transaction: Some(tx.clone()),
+									txid: tx.txid(), height, block_hash: Some(*block_hash), transaction: Some(tx.clone()),
 									event: OnchainEvent::HTLCSpendConfirmation {
 										commitment_tx_output_idx: input.previous_output.vout,
 										preimage: if accepted_preimage_claim || offered_preimage_claim {
@@ -3364,6 +3371,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 						self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry {
 							txid: tx.txid(),
 							height,
+							block_hash: Some(*block_hash),
 							transaction: Some(tx.clone()),
 							event: OnchainEvent::HTLCSpendConfirmation {
 								commitment_tx_output_idx: input.previous_output.vout,
@@ -3387,6 +3395,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 							txid: tx.txid(),
 							transaction: Some(tx.clone()),
 							height,
+							block_hash: Some(*block_hash),
 							event: OnchainEvent::HTLCSpendConfirmation {
 								commitment_tx_output_idx: input.previous_output.vout,
 								preimage: Some(payment_preimage),
@@ -3414,6 +3423,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 						txid: tx.txid(),
 						transaction: Some(tx.clone()),
 						height,
+						block_hash: Some(*block_hash),
 						event: OnchainEvent::HTLCUpdate {
 							source, payment_hash,
 							htlc_value_satoshis: Some(amount_msat / 1000),
@@ -3428,7 +3438,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 	}
 
 	/// Check if any transaction broadcasted is paying fund back to some address we can assume to own
-	fn is_paying_spendable_output<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) where L::Target: Logger {
+	fn is_paying_spendable_output<L: Deref>(&mut self, tx: &Transaction, height: u32, block_hash: &BlockHash, logger: &L) where L::Target: Logger {
 		let mut spendable_output = None;
 		for (i, outp) in tx.output.iter().enumerate() { // There is max one spendable output for any channel tx, including ones generated by us
 			if i > ::core::u16::MAX as usize {
@@ -3488,6 +3498,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				txid: tx.txid(),
 				transaction: Some(tx.clone()),
 				height,
+				block_hash: Some(*block_hash),
 				event: OnchainEvent::MaturingOutput { descriptor: spendable_output.clone() },
 			};
 			log_info!(logger, "Received spendable output {}, spendable at height {}", log_spendable!(spendable_output), entry.confirmation_threshold());
@@ -3529,7 +3540,7 @@ where
 		self.0.best_block_updated(header, height, &*self.1, &*self.2, &*self.3);
 	}
 
-	fn get_relevant_txids(&self) -> Vec<Txid> {
+	fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)> {
 		self.0.get_relevant_txids()
 	}
 }

lightning/src/chain/mod.rs

@@ -171,7 +171,8 @@ pub trait Confirm {
 	/// if they become available at the same time.
 	fn best_block_updated(&self, header: &BlockHeader, height: u32);
 
-	/// Returns transactions that should be monitored for reorganization out of the chain.
+	/// Returns transactions that should be monitored for reorganization out of the chain along
+	/// with the hash of the block as part of which had been previously confirmed.
 	///
 	/// Will include any transactions passed to [`transactions_confirmed`] that have insufficient
 	/// confirmations to be safe from a chain reorganization. Will not include any transactions
@@ -180,11 +181,13 @@ pub trait Confirm {
 	/// May be called to determine the subset of transactions that must still be monitored for
 	/// reorganization. Will be idempotent between calls but may change as a result of calls to the
 	/// other interface methods. Thus, this is useful to determine which transactions may need to be
-	/// given to [`transaction_unconfirmed`].
+	/// given to [`transaction_unconfirmed`]. If any of the returned transactions are confirmed in
+	/// a block other than the one with the given hash, they need to be unconfirmed and reconfirmed
+	/// via `transaction_unconfirmed` and `transactions_confirmed`, respectively.
 	///
 	/// [`transactions_confirmed`]: Self::transactions_confirmed
 	/// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
-	fn get_relevant_txids(&self) -> Vec<Txid>;
+	fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)>;
 }
 
 /// An enum representing the status of a channel monitor update persistence.

lightning/src/chain/onchaintx.rs

@@ -16,7 +16,7 @@ use bitcoin::blockdata::transaction::Transaction;
 use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
 use bitcoin::blockdata::script::Script;
 
-use bitcoin::hash_types::Txid;
+use bitcoin::hash_types::{Txid, BlockHash};
 
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
 use bitcoin::secp256k1;
@@ -58,6 +58,7 @@ const MAX_ALLOC_SIZE: usize = 64*1024;
 struct OnchainEventEntry {
 	txid: Txid,
 	height: u32,
+	block_hash: Option<BlockHash>, // Added as optional, will be filled in for any entry generated on 0.0.113 or after
 	event: OnchainEvent,
 }
 
@@ -92,6 +93,7 @@ impl Writeable for OnchainEventEntry {
 	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 		write_tlv_fields!(writer, {
 			(0, self.txid, required),
+			(1, self.block_hash, option),
 			(2, self.height, required),
 			(4, self.event, required),
 		});
@@ -103,14 +105,16 @@ impl MaybeReadable for OnchainEventEntry {
 	fn read<R: io::Read>(reader: &mut R) -> Result<Option<Self>, DecodeError> {
 		let mut txid = Txid::all_zeros();
 		let mut height = 0;
+		let mut block_hash = None;
 		let mut event = None;
 		read_tlv_fields!(reader, {
 			(0, txid, required),
+			(1, block_hash, option),
 			(2, height, required),
 			(4, event, ignorable),
 		});
 		if let Some(ev) = event {
-			Ok(Some(Self { txid, height, event: ev }))
+			Ok(Some(Self { txid, height, block_hash, event: ev }))
 		} else {
 			Ok(None)
 		}
@@ -860,12 +864,12 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 		self.claimable_outpoints.get(outpoint).is_some()
 	}
 
-	pub(crate) fn get_relevant_txids(&self) -> Vec<Txid> {
-		let mut txids: Vec<Txid> = self.onchain_events_awaiting_threshold_conf
+	pub(crate) fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)> {
+		let mut txids: Vec<(Txid, Option<BlockHash>)> = self.onchain_events_awaiting_threshold_conf
 			.iter()
-			.map(|entry| entry.txid)
+			.map(|entry| (entry.txid, entry.block_hash))
 			.collect();
-		txids.sort_unstable();
+		txids.sort_unstable_by_key(|(txid, _)| *txid);
 		txids.dedup();
 		txids
 	}

lightning/src/ln/channel.rs

@@ -4520,6 +4520,11 @@ impl<Signer: Sign> Channel<Signer> {
 		self.channel_transaction_parameters.funding_outpoint
 	}
 
+	/// Returns the block hash in which our funding transaction was confirmed.
+	pub fn get_funding_tx_confirmed_in(&self) -> Option<BlockHash> {
+		self.funding_tx_confirmed_in
+	}
+
 	fn get_holder_selected_contest_delay(&self) -> u16 {
 		self.channel_transaction_parameters.holder_selected_contest_delay
 	}