Track block hash, return in get_relevant_txids

Previously, `Confirm::get_relevant_txids()` returned a list of
transactions that have to be monitored for reorganization out of the
chain. This interface however required a 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, 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

@@ -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
@@ -184,7 +185,7 @@ pub trait Confirm {
 	///
 	/// [`transactions_confirmed`]: Self::transactions_confirmed
 	/// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
-	fn get_relevant_txids(&self) -> Vec<Txid>;
+	fn get_relevant_txids(&self) -> Vec<(Txid, BlockHash)>;
 }
 
 /// An enum representing the status of a channel monitor update persistence.

lightning/src/chain/mod.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>,
 	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)
 		}
@@ -512,7 +516,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	/// `conf_height` represents the height at which the transactions in `txn_matched` were
 	/// confirmed. This does not need to equal the current blockchain tip height, which should be
 	/// provided via `cur_height`, however it must never be higher than `cur_height`.
-	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, cur_height: u32, broadcaster: &B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
+	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, conf_hash: BlockHash, cur_height: u32, broadcaster: &B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator,
 					L::Target: Logger,
@@ -625,6 +629,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 								let entry = OnchainEventEntry {
 									txid: tx.txid(),
 									height: conf_height,
+									block_hash: Some(conf_hash),
 									event: OnchainEvent::Claim { claim_request: first_claim_txid_height.0.clone() }
 								};
 								if !self.onchain_events_awaiting_threshold_conf.contains(&entry) {
@@ -665,6 +670,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 				let entry = OnchainEventEntry {
 					txid: tx.txid(),
 					height: conf_height,
+					block_hash: Some(conf_hash),
 					event: OnchainEvent::ContentiousOutpoint { package },
 				};
 				if !self.onchain_events_awaiting_threshold_conf.contains(&entry) {
@@ -824,10 +830,10 @@ 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, BlockHash)> {
+		let mut txids: Vec<(Txid, BlockHash)> = self.onchain_events_awaiting_threshold_conf
 			.iter()
-			.map(|entry| entry.txid)
+			.map(|entry| (entry.txid, entry.block_hash.unwrap()))
 			.collect();
 		txids.sort_unstable();
 		txids.dedup();

lightning/src/chain/onchaintx.rs

@@ -4513,6 +4513,11 @@ 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
 	}

lightning/src/ln/channel.rs

@@ -5759,12 +5759,12 @@ where
 		});
 	}
 
-	fn get_relevant_txids(&self) -> Vec<Txid> {
+	fn get_relevant_txids(&self) -> Vec<(Txid, BlockHash)> {
 		let channel_state = self.channel_state.lock().unwrap();
 		let mut res = Vec::with_capacity(channel_state.short_to_chan_info.len());
 		for chan in channel_state.by_id.values() {
-			if let Some(funding_txo) = chan.get_funding_txo() {
-				res.push(funding_txo.txid);
+			if let (Some(funding_txo), Some(block_hash)) = (chan.get_funding_txo(), chan.get_funding_tx_confirmed_in()) {
+				res.push((funding_txo.txid, block_hash));
 			}
 		}
 		res

lightning/src/ln/channelmanager.rs

@@ -281,8 +281,9 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 	if !reorg_after_reload {
 		if use_funding_unconfirmed {
 			let relevant_txids = nodes[0].node.get_relevant_txids();
-			assert_eq!(&relevant_txids[..], &[chan.3.txid()]);
-			nodes[0].node.transaction_unconfirmed(&relevant_txids[0]);
+			let txid = relevant_txids[0].0;
+			assert_eq!(txid, chan.3.txid());
+			nodes[0].node.transaction_unconfirmed(&txid);
 		} else if connect_style == ConnectStyle::FullBlockViaListen {
 			disconnect_blocks(&nodes[0], CHAN_CONFIRM_DEPTH - 1);
 			assert_eq!(nodes[0].node.list_usable_channels().len(), 1);
@@ -350,8 +351,9 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 	if reorg_after_reload {
 		if use_funding_unconfirmed {
 			let relevant_txids = nodes[0].node.get_relevant_txids();
-			assert_eq!(&relevant_txids[..], &[chan.3.txid()]);
-			nodes[0].node.transaction_unconfirmed(&relevant_txids[0]);
+			let txid = relevant_txids[0].0;
+			assert_eq!(txid, chan.3.txid());
+			nodes[0].node.transaction_unconfirmed(&txid);
 		} else if connect_style == ConnectStyle::FullBlockViaListen {
 			disconnect_blocks(&nodes[0], CHAN_CONFIRM_DEPTH - 1);
 			assert_eq!(nodes[0].node.list_channels().len(), 1);