Merge pull request #2146 from valentinewallace/2023-03-blinded-pathfinding-groundwork
[rust-lightning] / lightning / src / ln / functional_tests.rs
index d56f1bd3d376ac91ea84a92d60eb7dccee34efd3..2b8c8b8e3414af084180668fcc70b0ad59409ee8 100644 (file)
@@ -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);
@@ -2894,7 +2894,7 @@ 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.
@@ -2902,7 +2902,7 @@ fn test_htlc_on_chain_success() {
        // 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();
@@ -2991,9 +2991,9 @@ fn do_test_htlc_on_chain_timeout(connect_style: ConnectStyle) {
                if nodes[1].connect_style.borrow().skips_blocks() {
                        assert_eq!(txn.len(), 1);
                } else {
-                       assert_eq!(txn.len(), 2); // Extra rebroadcast of timeout transaction
+                       assert_eq!(txn.len(), 3); // Two extra fee bumps for timeout transaction
                }
-               check_spends!(txn[0], commitment_tx[0]);
+               txn.iter().for_each(|tx| check_spends!(tx, commitment_tx[0]));
                assert_eq!(txn[0].clone().input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
                txn.remove(0)
        };
@@ -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);
@@ -3461,7 +3461,7 @@ fn test_htlc_ignore_latest_remote_commitment() {
 
        let node_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
        assert_eq!(node_txn.len(), 3);
-       assert_eq!(node_txn[0], node_txn[1]);
+       assert_eq!(node_txn[0].txid(), node_txn[1].txid());
 
        let mut 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![node_txn[0].clone(), node_txn[1].clone()]});
@@ -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;
@@ -7510,7 +7510,7 @@ fn test_bump_penalty_txn_on_remote_commitment() {
        assert_ne!(feerate_preimage, 0);
 
        // After exhaustion of height timer, new bumped claim txn should have been broadcast, check it
-       connect_blocks(&nodes[1], 15);
+       connect_blocks(&nodes[1], 1);
        {
                let mut node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap();
                assert_eq!(node_txn.len(), 1);
@@ -8434,7 +8434,7 @@ fn test_update_err_monitor_lockdown() {
        let block = Block { header, txdata: vec![] };
        // Make the tx_broadcaster aware of enough blocks that it doesn't think we're violating
        // transaction lock time requirements here.
-       chanmon_cfgs[0].tx_broadcaster.blocks.lock().unwrap().resize(200, (block.clone(), 0));
+       chanmon_cfgs[0].tx_broadcaster.blocks.lock().unwrap().resize(200, (block.clone(), 200));
        watchtower.chain_monitor.block_connected(&block, 200);
 
        // Try to update ChannelMonitor
@@ -8486,6 +8486,9 @@ fn test_concurrent_monitor_claim() {
        let chain_source = test_utils::TestChainSource::new(Network::Testnet);
        let logger = test_utils::TestLogger::with_id(format!("node {}", "Alice"));
        let persister = test_utils::TestPersister::new();
+       let alice_broadcaster = test_utils::TestBroadcaster::with_blocks(
+               Arc::new(Mutex::new(nodes[0].blocks.lock().unwrap().clone())),
+       );
        let watchtower_alice = {
                let new_monitor = {
                        let monitor = nodes[0].chain_monitor.chain_monitor.get_monitor(outpoint).unwrap();
@@ -8494,20 +8497,21 @@ fn test_concurrent_monitor_claim() {
                        assert!(new_monitor == *monitor);
                        new_monitor
                };
-               let watchtower = test_utils::TestChainMonitor::new(Some(&chain_source), &chanmon_cfgs[0].tx_broadcaster, &logger, &chanmon_cfgs[0].fee_estimator, &persister, &node_cfgs[0].keys_manager);
+               let watchtower = test_utils::TestChainMonitor::new(Some(&chain_source), &alice_broadcaster, &logger, &chanmon_cfgs[0].fee_estimator, &persister, &node_cfgs[0].keys_manager);
                assert_eq!(watchtower.watch_channel(outpoint, new_monitor), ChannelMonitorUpdateStatus::Completed);
                watchtower
        };
        let header = BlockHeader { version: 0x20000000, prev_blockhash: BlockHash::all_zeros(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42 };
        let block = Block { header, txdata: vec![] };
-       // Make the tx_broadcaster aware of enough blocks that it doesn't think we're violating
-       // transaction lock time requirements here.
-       chanmon_cfgs[0].tx_broadcaster.blocks.lock().unwrap().resize((CHAN_CONFIRM_DEPTH + 1 + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS) as usize, (block.clone(), 0));
-       watchtower_alice.chain_monitor.block_connected(&block, CHAN_CONFIRM_DEPTH + 1 + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS);
+       // Make Alice aware of enough blocks that it doesn't think we're violating transaction lock time
+       // requirements here.
+       const HTLC_TIMEOUT_BROADCAST: u32 = CHAN_CONFIRM_DEPTH + 1 + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS;
+       alice_broadcaster.blocks.lock().unwrap().resize((HTLC_TIMEOUT_BROADCAST) as usize, (block.clone(), HTLC_TIMEOUT_BROADCAST));
+       watchtower_alice.chain_monitor.block_connected(&block, HTLC_TIMEOUT_BROADCAST);
 
        // Watchtower Alice should have broadcast a commitment/HTLC-timeout
        let alice_state = {
-               let mut txn = chanmon_cfgs[0].tx_broadcaster.txn_broadcast();
+               let mut txn = alice_broadcaster.txn_broadcast();
                assert_eq!(txn.len(), 2);
                txn.remove(0)
        };
@@ -8516,6 +8520,7 @@ fn test_concurrent_monitor_claim() {
        let chain_source = test_utils::TestChainSource::new(Network::Testnet);
        let logger = test_utils::TestLogger::with_id(format!("node {}", "Bob"));
        let persister = test_utils::TestPersister::new();
+       let bob_broadcaster = test_utils::TestBroadcaster::with_blocks(Arc::clone(&alice_broadcaster.blocks));
        let watchtower_bob = {
                let new_monitor = {
                        let monitor = nodes[0].chain_monitor.chain_monitor.get_monitor(outpoint).unwrap();
@@ -8524,12 +8529,12 @@ fn test_concurrent_monitor_claim() {
                        assert!(new_monitor == *monitor);
                        new_monitor
                };
-               let watchtower = test_utils::TestChainMonitor::new(Some(&chain_source), &chanmon_cfgs[0].tx_broadcaster, &logger, &chanmon_cfgs[0].fee_estimator, &persister, &node_cfgs[0].keys_manager);
+               let watchtower = test_utils::TestChainMonitor::new(Some(&chain_source), &bob_broadcaster, &logger, &chanmon_cfgs[0].fee_estimator, &persister, &node_cfgs[0].keys_manager);
                assert_eq!(watchtower.watch_channel(outpoint, new_monitor), ChannelMonitorUpdateStatus::Completed);
                watchtower
        };
        let header = BlockHeader { version: 0x20000000, prev_blockhash: BlockHash::all_zeros(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42 };
-       watchtower_bob.chain_monitor.block_connected(&Block { header, txdata: vec![] }, CHAN_CONFIRM_DEPTH + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS);
+       watchtower_bob.chain_monitor.block_connected(&Block { header, txdata: vec![] }, HTLC_TIMEOUT_BROADCAST - 1);
 
        // Route another payment to generate another update with still previous HTLC pending
        let (route, payment_hash, _, payment_secret) = get_route_and_payment_hash!(nodes[1], nodes[0], 3000000);
@@ -8556,21 +8561,26 @@ fn test_concurrent_monitor_claim() {
 
        //// Provide one more block to watchtower Bob, expect broadcast of commitment and HTLC-Timeout
        let header = BlockHeader { version: 0x20000000, prev_blockhash: BlockHash::all_zeros(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42 };
-       watchtower_bob.chain_monitor.block_connected(&Block { header, txdata: vec![] }, CHAN_CONFIRM_DEPTH + 1 + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS);
+       watchtower_bob.chain_monitor.block_connected(&Block { header, txdata: vec![] }, HTLC_TIMEOUT_BROADCAST);
 
        // Watchtower Bob should have broadcast a commitment/HTLC-timeout
        let bob_state_y;
        {
-               let mut txn = chanmon_cfgs[0].tx_broadcaster.txn_broadcast();
+               let mut txn = bob_broadcaster.txn_broadcast();
                assert_eq!(txn.len(), 2);
                bob_state_y = txn.remove(0);
        };
 
        // We confirm Bob's state Y on Alice, she should broadcast a HTLC-timeout
        let header = BlockHeader { version: 0x20000000, prev_blockhash: BlockHash::all_zeros(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42 };
-       watchtower_alice.chain_monitor.block_connected(&Block { header, txdata: vec![bob_state_y.clone()] }, CHAN_CONFIRM_DEPTH + 2 + TEST_FINAL_CLTV + LATENCY_GRACE_PERIOD_BLOCKS);
+       let height = HTLC_TIMEOUT_BROADCAST + 1;
+       connect_blocks(&nodes[0], height - nodes[0].best_block_info().1);
+       check_closed_broadcast(&nodes[0], 1, true);
+       check_closed_event(&nodes[0], 1, ClosureReason::CommitmentTxConfirmed, false);
+       watchtower_alice.chain_monitor.block_connected(&Block { header, txdata: vec![bob_state_y.clone()] }, height);
+       check_added_monitors(&nodes[0], 1);
        {
-               let htlc_txn = chanmon_cfgs[0].tx_broadcaster.txn_broadcast();
+               let htlc_txn = alice_broadcaster.txn_broadcast();
                assert_eq!(htlc_txn.len(), 2);
                check_spends!(htlc_txn[0], bob_state_y);
                // Alice doesn't clean up the old HTLC claim since it hasn't seen a conflicting spend for
@@ -8650,7 +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();
@@ -9248,7 +9258,7 @@ fn do_test_tx_confirmed_skipping_blocks_immediate_broadcast(test_height_before_t
                // We should broadcast an HTLC transaction spending our funding transaction first
                let spending_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0);
                assert_eq!(spending_txn.len(), 2);
-               assert_eq!(spending_txn[0], node_txn[0]);
+               assert_eq!(spending_txn[0].txid(), node_txn[0].txid());
                check_spends!(spending_txn[1], node_txn[0]);
                // We should also generate a SpendableOutputs event with the to_self output (as its
                // timelock is up).
@@ -9826,8 +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(),
                        }]}
                },
@@ -9841,7 +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());