Add test_static_spendable_outputs_preimage_tx

Aims to covered both keysinterace preimage tx case and
detection of second remote commitment tx

Author: Antoine Riard

src/ln/channelmanager.rs

@@ -3226,6 +3226,8 @@ mod tests {
 
 	use bitcoin::util::hash::Sha256dHash;
 	use bitcoin::util::bip143;
+	use bitcoin::util::address::Address;
+	use bitcoin::util::bip32::{ChildNumber, ExtendedPubKey, ExtendedPrivKey};
 	use bitcoin::blockdata::block::{Block, BlockHeader};
 	use bitcoin::blockdata::transaction::{Transaction, TxOut, TxIn, SigHashType};
 	use bitcoin::blockdata::script::{Builder, Script};
@@ -7550,4 +7552,89 @@ mod tests {
 		};
 		check_spends!(spend_tx, node_txn[0].clone());
 	}
+
+	#[test]
+	fn test_static_spendable_outputs_preimage_tx() {
+		let nodes = create_network(2);
+
+		// Create some initial channels
+		let chan_1 = create_announced_chan_between_nodes(&nodes, 0, 1);
+
+		let payment_preimage = route_payment(&nodes[0], &vec!(&nodes[1])[..], 3000000).0;
+
+		let commitment_tx = nodes[0].node.channel_state.lock().unwrap().by_id.get(&chan_1.2).unwrap().last_local_commitment_txn.clone();
+		assert_eq!(commitment_tx[0].input.len(), 1);
+		assert_eq!(commitment_tx[0].input[0].previous_output.txid, chan_1.3.txid());
+
+		// Settle A's commitment tx on B's chain
+		let header = BlockHeader { version: 0x20000000, prev_blockhash: Default::default(), merkle_root: Default::default(), time: 42, bits: 42, nonce: 42 };
+		assert!(nodes[1].node.claim_funds(payment_preimage));
+		check_added_monitors!(nodes[1], 1);
+		nodes[1].chain_monitor.block_connected_with_filtering(&Block { header, txdata: vec![commitment_tx[0].clone()] }, 1);
+		let events = nodes[1].node.get_and_clear_pending_msg_events();
+		match events[0] {
+			MessageSendEvent::UpdateHTLCs { .. } => {},
+			_ => panic!("Unexpected event"),
+		}
+		match events[1] {
+			MessageSendEvent::BroadcastChannelUpdate { .. } => {},
+			_ => panic!("Unexepected event"),
+		}
+
+		// Check B's monitor was able to send back output descriptor event for preimage tx on A's commitment tx
+		let node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap(); // ChannelManager : 1 (local commitment tx), ChannelMonitor: 2 (1 preimage tx) * 2 (block-rescan)
+		check_spends!(node_txn[0], commitment_tx[0].clone());
+		assert_eq!(node_txn[0], node_txn[2]);
+		assert_eq!(node_txn[0].input[0].witness.last().unwrap().len(), 133);
+		check_spends!(node_txn[1], chan_1.3.clone());
+
+		let events = nodes[1].chan_monitor.simple_monitor.get_and_clear_pending_events();
+		let spend_tx = match events[0] {
+			Event::SpendableOutputs { ref outputs } => {
+				match outputs[0] {
+					SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
+						let secp_ctx = Secp256k1::new();
+						let input = TxIn {
+							previous_output: outpoint.clone(),
+							script_sig: Script::new(),
+							sequence: 0,
+							witness: Vec::new(),
+						};
+						let outp = TxOut {
+							script_pubkey: Builder::new().push_opcode(opcodes::All::OP_RETURN).into_script(),
+							value: output.value,
+						};
+						let mut spend_tx = Transaction {
+							version: 2,
+							lock_time: 0,
+							input: vec![input],
+							output: vec![outp.clone()],
+						};
+						let destination_secret = {
+							match ExtendedPrivKey::new_master(&secp_ctx, Network::Testnet, &nodes[1].node_seed) {
+								Ok(master_key) => {
+									match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
+										Ok(destination_key) => destination_key,
+										Err(_) => panic!("Your RNG is busted"),
+									}
+								}
+								Err(_) => panic!("Your rng is busted"),
+							}
+						};
+						let destination_pubkey = ExtendedPubKey::from_private(&secp_ctx, &destination_secret).public_key;
+						let witness_script = Address::p2pkh(&destination_pubkey, Network::Testnet).script_pubkey();
+						let sighash = Message::from_slice(&bip143::SighashComponents::new(&spend_tx).sighash_all(&spend_tx.input[0], &witness_script, output.value)[..]).unwrap();
+						let sig = secp_ctx.sign(&sighash, &destination_secret.secret_key);
+						spend_tx.input[0].witness.push(sig.serialize_der(&secp_ctx).to_vec());
+						spend_tx.input[0].witness[0].push(SigHashType::All as u8);
+						spend_tx.input[0].witness.push(destination_pubkey.serialize().to_vec());
+						spend_tx
+					},
+					_ => panic!("Unexpected event !"),
+				}
+			},
+			_ => panic!("Unexpected event !"),
+		};
+		check_spends!(spend_tx, node_txn[0].clone());
+	}
 }