Fix off-by-one finalized transaction locktime

While these transactions were still valid, we incorrectly assumed that
they would propagate with a locktime of `current_height + 1`, when in
reality, only those with a locktime strictly lower than the next height
in the chain are allowed to enter the mempool.

Author: wpaulino

lightning/src/chain/onchaintx.rs

@@ -748,8 +748,8 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 			preprocessed_requests.push(req);
 		}
 
-		// Claim everything up to and including cur_height + 1
-		let remaining_locked_packages = self.locktimed_packages.split_off(&(cur_height + 2));
+		// Claim everything up to and including `cur_height`
+		let remaining_locked_packages = self.locktimed_packages.split_off(&(cur_height + 1));
 		for (pop_height, mut entry) in self.locktimed_packages.iter_mut() {
 			log_trace!(logger, "Restoring delayed claim of package(s) at their timelock at {}.", pop_height);
 			preprocessed_requests.append(&mut entry);

lightning/src/chain/package.rs

@@ -460,13 +460,13 @@ impl PackageSolvingData {
 		}
 	}
 	fn absolute_tx_timelock(&self, current_height: u32) -> u32 {
-		// We use `current_height + 1` as our default locktime to discourage fee sniping and because
+		// We use `current_height` as our default locktime to discourage fee sniping and because
 		// transactions with it always propagate.
 		let absolute_timelock = match self {
-			PackageSolvingData::RevokedOutput(_) => current_height + 1,
-			PackageSolvingData::RevokedHTLCOutput(_) => current_height + 1,
-			PackageSolvingData::CounterpartyOfferedHTLCOutput(_) => current_height + 1,
-			PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => cmp::max(outp.htlc.cltv_expiry, current_height + 1),
+			PackageSolvingData::RevokedOutput(_) => current_height,
+			PackageSolvingData::RevokedHTLCOutput(_) => current_height,
+			PackageSolvingData::CounterpartyOfferedHTLCOutput(_) => current_height,
+			PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => cmp::max(outp.htlc.cltv_expiry, current_height),
 			// HTLC timeout/success transactions rely on a fixed timelock due to the counterparty's
 			// signature.
 			PackageSolvingData::HolderHTLCOutput(ref outp) => {
@@ -475,7 +475,7 @@ impl PackageSolvingData {
 				}
 				outp.cltv_expiry
 			},
-			PackageSolvingData::HolderFundingOutput(_) => current_height + 1,
+			PackageSolvingData::HolderFundingOutput(_) => current_height,
 		};
 		absolute_timelock
 	}

lightning/src/ln/channelmanager.rs

@@ -3006,10 +3006,11 @@ where
 		}
 		{
 			let height = self.best_block.read().unwrap().height();
-			// Transactions are evaluated as final by network mempools at the next block. However, the modules
-			// constituting our Lightning node might not have perfect sync about their blockchain views. Thus, if
-			// the wallet module is in advance on the LDK view, allow one more block of headroom.
-			if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) && LockTime::from(funding_transaction.lock_time).is_block_height() && funding_transaction.lock_time.0 > height + 2 {
+			// Transactions are evaluated as final by network mempools if their locktime is strictly
+			// lower than the next block height. However, the modules constituting our Lightning
+			// node might not have perfect sync about their blockchain views. Thus, if the wallet
+			// module is ahead of LDK, only allow one more block of headroom.
+			if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) && LockTime::from(funding_transaction.lock_time).is_block_height() && funding_transaction.lock_time.0 > height + 1 {
 				return Err(APIError::APIMisuseError {
 					err: "Funding transaction absolute timelock is non-final".to_owned()
 				});

lightning/src/ln/functional_test_utils.rs

@@ -230,6 +230,9 @@ fn do_connect_block<'a, 'b, 'c, 'd>(node: &'a Node<'b, 'c, 'd>, block: Block, sk
 	#[cfg(feature = "std")] {
 		eprintln!("Connecting block using Block Connection Style: {:?}", *node.connect_style.borrow());
 	}
+	// Update the block internally before handing it over to LDK, to ensure our assertions regarding
+	// transaction broadcast are correct.
+	node.blocks.lock().unwrap().push((block.clone(), height));
 	if !skip_intermediaries {
 		let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
 		match *node.connect_style.borrow() {
@@ -279,7 +282,6 @@ fn do_connect_block<'a, 'b, 'c, 'd>(node: &'a Node<'b, 'c, 'd>, block: Block, sk
 	}
 	call_claimable_balances(node);
 	node.node.test_process_background_events();
-	node.blocks.lock().unwrap().push((block, height));
 }
 
 pub fn disconnect_blocks<'a, 'b, 'c, 'd>(node: &'a Node<'b, 'c, 'd>, count: u32) {

lightning/src/ln/functional_tests.rs

@@ -1284,7 +1284,7 @@ fn test_duplicate_htlc_different_direction_onchain() {
 	mine_transaction(&nodes[0], &remote_txn[0]);
 	check_added_monitors!(nodes[0], 1);
 	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 
 	let claim_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().clone();
 	assert_eq!(claim_txn.len(), 3);
@@ -2438,7 +2438,7 @@ fn test_justice_tx_htlc_timeout() {
 		test_txn_broadcast(&nodes[1], &chan_5, Some(revoked_local_txn[0].clone()), HTLCType::NONE);
 
 		mine_transaction(&nodes[0], &revoked_local_txn[0]);
-		connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+		connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 		// Verify broadcast of revoked HTLC-timeout
 		let node_txn = test_txn_broadcast(&nodes[0], &chan_5, Some(revoked_local_txn[0].clone()), HTLCType::TIMEOUT);
 		check_added_monitors!(nodes[0], 1);
@@ -2765,7 +2765,7 @@ fn test_htlc_on_chain_success() {
 	// Verify that B's ChannelManager is able to extract preimage from HTLC Success tx and pass it backward
 	let header = BlockHeader { version: 0x20000000, prev_blockhash: nodes[1].best_block_hash(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42};
 	connect_block(&nodes[1], &Block { header, txdata: vec![commitment_tx[0].clone(), node_txn[0].clone(), node_txn[1].clone()]});
-	connect_blocks(&nodes[1], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[1], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 	{
 		let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
 		assert_eq!(added_monitors.len(), 1);
@@ -2894,15 +2894,15 @@ fn test_htlc_on_chain_success() {
 	assert_eq!(commitment_spend.input.len(), 2);
 	assert_eq!(commitment_spend.input[0].witness.last().unwrap().len(), OFFERED_HTLC_SCRIPT_WEIGHT);
 	assert_eq!(commitment_spend.input[1].witness.last().unwrap().len(), OFFERED_HTLC_SCRIPT_WEIGHT);
-	assert_eq!(commitment_spend.lock_time.0, nodes[1].best_block_info().1 + 1);
+	assert_eq!(commitment_spend.lock_time.0, nodes[1].best_block_info().1);
 	assert!(commitment_spend.output[0].script_pubkey.is_v0_p2wpkh()); // direct payment
 	// We don't bother to check that B can claim the HTLC output on its commitment tx here as
 	// we already checked the same situation with A.
 
 	// Verify that A's ChannelManager is able to extract preimage from preimage tx and generate PaymentSent
 	let mut header = BlockHeader { version: 0x20000000, prev_blockhash: nodes[0].best_block_hash(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42};
 	connect_block(&nodes[0], &Block { header, txdata: vec![node_a_commitment_tx[0].clone(), commitment_spend.clone()] });
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV + MIN_CLTV_EXPIRY_DELTA as u32 - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV + MIN_CLTV_EXPIRY_DELTA as u32); // Confirm blocks until the HTLC expires
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
 	let events = nodes[0].node.get_and_clear_pending_events();
@@ -3024,7 +3024,7 @@ fn do_test_htlc_on_chain_timeout(connect_style: ConnectStyle) {
 	check_spends!(commitment_tx[0], chan_1.3);
 
 	mine_transaction(&nodes[0], &commitment_tx[0]);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV + MIN_CLTV_EXPIRY_DELTA as u32 - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV + MIN_CLTV_EXPIRY_DELTA as u32); // Confirm blocks until the HTLC expires
 
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
@@ -4446,7 +4446,7 @@ fn test_static_spendable_outputs_timeout_tx() {
 		MessageSendEvent::BroadcastChannelUpdate { .. } => {},
 		_ => panic!("Unexpected event"),
 	}
-	connect_blocks(&nodes[1], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[1], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 
 	// Check B's monitor was able to send back output descriptor event for timeout tx on A's commitment tx
 	let node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
@@ -4524,7 +4524,7 @@ fn test_static_spendable_outputs_justice_tx_revoked_htlc_timeout_tx() {
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
 	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 
 	let revoked_htlc_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
 	assert_eq!(revoked_htlc_txn.len(), 1);
@@ -4756,7 +4756,7 @@ fn test_onchain_to_onchain_claim() {
 	check_spends!(b_txn[0], commitment_tx[0]);
 	assert_eq!(b_txn[0].input[0].witness.clone().last().unwrap().len(), OFFERED_HTLC_SCRIPT_WEIGHT);
 	assert!(b_txn[0].output[0].script_pubkey.is_v0_p2wpkh()); // direct payment
-	assert_eq!(b_txn[0].lock_time.0, nodes[1].best_block_info().1 + 1); // Success tx
+	assert_eq!(b_txn[0].lock_time.0, nodes[1].best_block_info().1); // Success tx
 
 	check_closed_broadcast!(nodes[1], true);
 	check_added_monitors!(nodes[1], 1);
@@ -4807,7 +4807,7 @@ fn test_duplicate_payment_hash_one_failure_one_success() {
 	check_closed_broadcast!(nodes[1], true);
 	check_added_monitors!(nodes[1], 1);
 	check_closed_event!(nodes[1], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[1], TEST_FINAL_CLTV - 40 + MIN_CLTV_EXPIRY_DELTA as u32 - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[1], TEST_FINAL_CLTV - 40 + MIN_CLTV_EXPIRY_DELTA as u32); // Confirm blocks until the HTLC expires
 
 	let htlc_timeout_tx;
 	{ // Extract one of the two HTLC-Timeout transaction
@@ -5287,7 +5287,7 @@ fn test_dynamic_spendable_outputs_local_htlc_timeout_tx() {
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
 	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 
 	let htlc_timeout = {
 		let node_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap();
@@ -5370,7 +5370,7 @@ fn test_key_derivation_params() {
 
 	// Timeout HTLC on A's chain and so it can generate a HTLC-Timeout tx
 	mine_transaction(&nodes[0], &local_txn_1[0]);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
 	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
@@ -6927,7 +6927,7 @@ fn do_test_sweep_outbound_htlc_failure_update(revoked: bool, local: bool) {
 		check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
 		assert_eq!(nodes[0].node.get_and_clear_pending_events().len(), 0);
 
-		connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+		connect_blocks(&nodes[0], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 		timeout_tx = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().drain(..)
 			.filter(|tx| tx.input[0].previous_output.txid == bs_commitment_tx[0].txid()).collect();
 		check_spends!(timeout_tx[0], bs_commitment_tx[0]);
@@ -6938,7 +6938,7 @@ fn do_test_sweep_outbound_htlc_failure_update(revoked: bool, local: bool) {
 		if !revoked {
 			assert_eq!(timeout_tx[0].input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
 		} else {
-			assert_eq!(timeout_tx[0].lock_time.0, 12);
+			assert_eq!(timeout_tx[0].lock_time.0, 11);
 		}
 		// We fail non-dust-HTLC 2 by broadcast of local timeout/revocation-claim tx
 		mine_transaction(&nodes[0], &timeout_tx[0]);
@@ -7318,7 +7318,7 @@ fn test_bump_penalty_txn_on_revoked_htlcs() {
 	check_closed_broadcast!(nodes[1], true);
 	check_added_monitors!(nodes[1], 1);
 	check_closed_event!(nodes[1], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[1], 49); // Confirm blocks until the HTLC expires (note CLTV was explicitly 50 above)
+	connect_blocks(&nodes[1], 50); // Confirm blocks until the HTLC expires (note CLTV was explicitly 50 above)
 
 	let revoked_htlc_txn = {
 		let txn = nodes[1].tx_broadcaster.unique_txn_broadcast();
@@ -7464,7 +7464,7 @@ fn test_bump_penalty_txn_on_remote_commitment() {
 	expect_payment_claimed!(nodes[1], payment_hash, 3_000_000);
 	mine_transaction(&nodes[1], &remote_txn[0]);
 	check_added_monitors!(nodes[1], 2);
-	connect_blocks(&nodes[1], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+	connect_blocks(&nodes[1], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 
 	// One or more claim tx should have been broadcast, check it
 	let timeout;
@@ -8660,7 +8660,7 @@ fn test_htlc_no_detection() {
 	check_closed_broadcast!(nodes[0], true);
 	check_added_monitors!(nodes[0], 1);
 	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1);
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV);
 
 	let htlc_timeout = {
 		let node_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap();
@@ -9836,8 +9836,8 @@ fn test_non_final_funding_tx() {
 	assert_eq!(events.len(), 1);
 	let mut tx = match events[0] {
 		Event::FundingGenerationReady { ref channel_value_satoshis, ref output_script, .. } => {
-			// Timelock the transaction _beyond_ the best client height + 2.
-			Transaction { version: chan_id as i32, lock_time: PackedLockTime(best_height + 3), input: vec![input], output: vec![TxOut {
+			// Timelock the transaction _beyond_ the best client height + 1.
+			Transaction { version: chan_id as i32, lock_time: PackedLockTime(best_height + 2), input: vec![input], output: vec![TxOut {
 				value: *channel_value_satoshis, script_pubkey: output_script.clone(),
 			}]}
 		},
@@ -9851,7 +9851,7 @@ fn test_non_final_funding_tx() {
 		_ => panic!()
 	}
 
-	// However, transaction should be accepted if it's in a +2 headroom from best block.
+	// However, transaction should be accepted if it's in a +1 headroom from best block.
 	tx.lock_time = PackedLockTime(tx.lock_time.0 - 1);
 	assert!(nodes[0].node.funding_transaction_generated(&temp_channel_id, &nodes[1].node.get_our_node_id(), tx.clone()).is_ok());
 	get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());

lightning/src/ln/monitor_tests.rs

@@ -497,7 +497,7 @@ fn do_test_claim_value_force_close(prev_commitment_tx: bool) {
 		nodes[0].chain_monitor.chain_monitor.get_monitor(funding_outpoint).unwrap().get_claimable_balances());
 
 	// When the HTLC timeout output is spendable in the next block, A should broadcast it
-	connect_blocks(&nodes[0], htlc_cltv_timeout - nodes[0].best_block_info().1 - 1);
+	connect_blocks(&nodes[0], htlc_cltv_timeout - nodes[0].best_block_info().1);
 	let a_broadcast_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
 	assert_eq!(a_broadcast_txn.len(), 2);
 	assert_eq!(a_broadcast_txn[0].input.len(), 1);
@@ -887,7 +887,7 @@ fn test_no_preimage_inbound_htlc_balances() {
 	// HTLC has been spent, even after the HTLC expires. We'll also fail the inbound HTLC, but it
 	// won't do anything as the channel is already closed.
 
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1);
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV);
 	let as_htlc_timeout_claim = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
 	assert_eq!(as_htlc_timeout_claim.len(), 1);
 	check_spends!(as_htlc_timeout_claim[0], as_txn[0]);
@@ -908,7 +908,7 @@ fn test_no_preimage_inbound_htlc_balances() {
 
 	// The next few blocks for B look the same as for A, though for the opposite HTLC
 	nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().clear();
-	connect_blocks(&nodes[1], TEST_FINAL_CLTV - (ANTI_REORG_DELAY - 1) - 1);
+	connect_blocks(&nodes[1], TEST_FINAL_CLTV - (ANTI_REORG_DELAY - 1));
 	expect_pending_htlcs_forwardable_conditions!(nodes[1],
 		[HTLCDestination::FailedPayment { payment_hash: to_b_failed_payment_hash }]);
 	let bs_htlc_timeout_claim = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
@@ -1734,7 +1734,7 @@ fn do_test_restored_packages_retry(check_old_monitor_retries_after_upgrade: bool
 	mine_transaction(&nodes[0], &commitment_tx);
 
 	// Connect blocks until the HTLC's expiration is met, expecting a transaction broadcast.
-	connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1);
+	connect_blocks(&nodes[0], TEST_FINAL_CLTV);
 	let htlc_timeout_tx = {
 		let mut txn = nodes[0].tx_broadcaster.txn_broadcast();
 		assert_eq!(txn.len(), 1);
@@ -1885,7 +1885,7 @@ fn do_test_monitor_rebroadcast_pending_claims(anchors: bool) {
 	};
 
 	// Connect blocks up to one before the HTLC expires. This should not result in a claim/retry.
-	connect_blocks(&nodes[0], htlc_expiry - nodes[0].best_block_info().1 - 2);
+	connect_blocks(&nodes[0], htlc_expiry - nodes[0].best_block_info().1 - 1);
 	check_htlc_retry(false, false);
 
 	// Connect one more block, producing our first claim.

lightning/src/ln/payment_tests.rs

@@ -562,8 +562,8 @@ fn do_test_completed_payment_not_retryable_on_reload(use_dust: bool) {
 	mine_transaction(&nodes[0], &bs_commitment_tx[0]);
 	mine_transaction(&nodes[1], &bs_commitment_tx[0]);
 	if !use_dust {
-		connect_blocks(&nodes[0], TEST_FINAL_CLTV - 1 + (MIN_CLTV_EXPIRY_DELTA as u32));
-		connect_blocks(&nodes[1], TEST_FINAL_CLTV - 1 + (MIN_CLTV_EXPIRY_DELTA as u32));
+		connect_blocks(&nodes[0], TEST_FINAL_CLTV + (MIN_CLTV_EXPIRY_DELTA as u32));
+		connect_blocks(&nodes[1], TEST_FINAL_CLTV + (MIN_CLTV_EXPIRY_DELTA as u32));
 		let as_htlc_timeout = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
 		check_spends!(as_htlc_timeout[0], bs_commitment_tx[0]);
 		assert_eq!(as_htlc_timeout.len(), 1);

lightning/src/ln/reload_tests.rs

@@ -948,7 +948,7 @@ fn do_forwarded_payment_no_manager_persistence(use_cs_commitment: bool, claim_ht
 		if claim_htlc {
 			confirm_transaction(&nodes[1], &cs_commitment_tx[1]);
 		} else {
-			connect_blocks(&nodes[1], htlc_expiry - nodes[1].best_block_info().1);
+			connect_blocks(&nodes[1], htlc_expiry - nodes[1].best_block_info().1 + 1);
 			let bs_htlc_timeout_tx = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
 			assert_eq!(bs_htlc_timeout_tx.len(), 1);
 			confirm_transaction(&nodes[1], &bs_htlc_timeout_tx[0]);

lightning/src/ln/reorg_tests.rs

@@ -103,7 +103,7 @@ fn do_test_onchain_htlc_reorg(local_commitment: bool, claim: bool) {
 
 		// Give node 1 node 2's commitment transaction and get its response (timing the HTLC out)
 		mine_transaction(&nodes[1], &node_2_commitment_txn[0]);
-		connect_blocks(&nodes[1], TEST_FINAL_CLTV - 1); // Confirm blocks until the HTLC expires
+		connect_blocks(&nodes[1], TEST_FINAL_CLTV); // Confirm blocks until the HTLC expires
 		let node_1_commitment_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().clone();
 		assert_eq!(node_1_commitment_txn.len(), 1); // ChannelMonitor: 1 offered HTLC-Timeout
 		check_spends!(node_1_commitment_txn[0], node_2_commitment_txn[0]);

lightning/src/util/test_utils.rs

@@ -335,7 +335,7 @@ impl chaininterface::BroadcasterInterface for TestBroadcaster {
 	fn broadcast_transaction(&self, tx: &Transaction) {
 		let lock_time = tx.lock_time.0;
 		assert!(lock_time < 1_500_000_000);
-		if lock_time > self.blocks.lock().unwrap().len() as u32 + 1 && lock_time < 500_000_000 {
+		if bitcoin::LockTime::from(tx.lock_time).is_block_height() && lock_time > self.blocks.lock().unwrap().last().unwrap().1 {
 			for inp in tx.input.iter() {
 				if inp.sequence != Sequence::MAX {
 					panic!("We should never broadcast a transaction before its locktime ({})!", tx.lock_time);