Add channel_id to SpendableOutputs event

    This will make it possible to
    link between SpendableOuts and ChannelMonitor

    - change channel_id to option so we dont break upgrade
    - remove unused channel_id
    - document channel_id
    - extract channel id dynamically to pass test

lightning/src/chain/channelmonitor.rs

@@ -3365,7 +3365,8 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 				OnchainEvent::MaturingOutput { descriptor } => {
 					log_debug!(logger, "Descriptor {} has got enough confirmations to be passed upstream", log_spendable!(descriptor));
 					self.pending_events.push(Event::SpendableOutputs {
-						outputs: vec![descriptor]
+						outputs: vec![descriptor],
+						channel_id: Some(self.funding_info.0.to_channel_id()),
 					});
 					self.spendable_txids_confirmed.push(entry.txid);
 				},

lightning/src/events/mod.rs

@@ -673,6 +673,10 @@ pub enum Event {
 	SpendableOutputs {
 		/// The outputs which you should store as spendable by you.
 		outputs: Vec<SpendableOutputDescriptor>,
+		/// Channel id to help you locate the corresponding `ChannelMonitor`,
+		/// We define this as an option so we dont break backwards compatibility.
+		/// This will always be `Some` for events generated by LDK versions 0.0.XX and above.
+		channel_id: Option<[u8; 32]>,
 	},
 	/// This event is generated when a payment has been successfully forwarded through us and a
 	/// forwarding fee earned.
@@ -958,10 +962,11 @@ impl Writeable for Event {
 				// Note that we now ignore these on the read end as we'll re-generate them in
 				// ChannelManager, we write them here only for backwards compatibility.
 			},
-			&Event::SpendableOutputs { ref outputs } => {
+			&Event::SpendableOutputs { ref outputs, channel_id } => {
 				5u8.write(writer)?;
 				write_tlv_fields!(writer, {
 					(0, WithoutLength(outputs), required),
+					(1, channel_id, option),
 				});
 			},
 			&Event::HTLCIntercepted { requested_next_hop_scid, payment_hash, inbound_amount_msat, expected_outbound_amount_msat, intercept_id } => {
@@ -1230,10 +1235,12 @@ impl MaybeReadable for Event {
 			5u8 => {
 				let f = || {
 					let mut outputs = WithoutLength(Vec::new());
+					let mut channel_id: Option<[u8; 32]> = None;
 					read_tlv_fields!(reader, {
 						(0, outputs, required),
+						(1, channel_id, option),
 					});
-					Ok(Some(Event::SpendableOutputs { outputs: outputs.0 }))
+					Ok(Some(Event::SpendableOutputs { outputs: outputs.0, channel_id }))
 				};
 				f()
 			},

lightning/src/ln/functional_tests.rs

@@ -4302,7 +4302,7 @@ macro_rules! check_spendable_outputs {
 			let secp_ctx = Secp256k1::new();
 			for event in events.drain(..) {
 				match event {
-					Event::SpendableOutputs { mut outputs } => {
+					Event::SpendableOutputs { mut outputs, channel_id: _ } => {
 						for outp in outputs.drain(..) {
 							txn.push($keysinterface.backing.spend_spendable_outputs(&[&outp], Vec::new(), Builder::new().push_opcode(opcodes::all::OP_RETURN).into_script(), 253, None, &secp_ctx).unwrap());
 							all_outputs.push(outp);

lightning/src/ln/monitor_tests.rs

@@ -95,7 +95,7 @@ fn chanmon_fail_from_stale_commitment() {
 fn test_spendable_output<'a, 'b, 'c, 'd>(node: &'a Node<'b, 'c, 'd>, spendable_tx: &Transaction) {
 	let mut spendable = node.chain_monitor.chain_monitor.get_and_clear_pending_events();
 	assert_eq!(spendable.len(), 1);
-	if let Event::SpendableOutputs { outputs } = spendable.pop().unwrap() {
+	if let Event::SpendableOutputs { outputs, .. } = spendable.pop().unwrap() {
 		assert_eq!(outputs.len(), 1);
 		let spend_tx = node.keys_manager.backing.spend_spendable_outputs(&[&outputs[0]], Vec::new(),
 			Builder::new().push_opcode(opcodes::all::OP_RETURN).into_script(), 253, None, &Secp256k1::new()).unwrap();
@@ -2228,8 +2228,9 @@ fn test_anchors_aggregated_revoked_htlc_tx() {
 	let spendable_output_events = nodes[0].chain_monitor.chain_monitor.get_and_clear_pending_events();
 	assert_eq!(spendable_output_events.len(), 2);
 	for (idx, event) in spendable_output_events.iter().enumerate() {
-		if let Event::SpendableOutputs { outputs } = event {
+		if let Event::SpendableOutputs { outputs, channel_id } = event {
 			assert_eq!(outputs.len(), 1);
+			assert_eq!(channel_id, &Some(vec![chan_a.2, chan_b.2][idx]));
 			let spend_tx = nodes[0].keys_manager.backing.spend_spendable_outputs(
 				&[&outputs[0]], Vec::new(), Script::new_op_return(&[]), 253, None, &Secp256k1::new(),
 			).unwrap();

lightning/src/ln/reorg_tests.rs

@@ -578,8 +578,9 @@ fn do_test_to_remote_after_local_detection(style: ConnectStyle) {
 
 	let mut node_a_spendable = nodes[0].chain_monitor.chain_monitor.get_and_clear_pending_events();
 	assert_eq!(node_a_spendable.len(), 1);
-	if let Event::SpendableOutputs { outputs } = node_a_spendable.pop().unwrap() {
+	if let Event::SpendableOutputs { outputs, channel_id } = node_a_spendable.pop().unwrap() {
 		assert_eq!(outputs.len(), 1);
+		assert_eq!(channel_id, Some(chan_id));
 		let spend_tx = nodes[0].keys_manager.backing.spend_spendable_outputs(&[&outputs[0]], Vec::new(),
 			Builder::new().push_opcode(opcodes::all::OP_RETURN).into_script(), 253, None, &Secp256k1::new()).unwrap();
 		check_spends!(spend_tx, remote_txn_b[0]);
@@ -598,8 +599,9 @@ fn do_test_to_remote_after_local_detection(style: ConnectStyle) {
 
 	let mut node_b_spendable = nodes[1].chain_monitor.chain_monitor.get_and_clear_pending_events();
 	assert_eq!(node_b_spendable.len(), 1);
-	if let Event::SpendableOutputs { outputs } = node_b_spendable.pop().unwrap() {
+	if let Event::SpendableOutputs { outputs, channel_id } = node_b_spendable.pop().unwrap() {
 		assert_eq!(outputs.len(), 1);
+		assert_eq!(channel_id, Some(chan_id));
 		let spend_tx = nodes[1].keys_manager.backing.spend_spendable_outputs(&[&outputs[0]], Vec::new(),
 			Builder::new().push_opcode(opcodes::all::OP_RETURN).into_script(), 253, None, &Secp256k1::new()).unwrap();
 		check_spends!(spend_tx, remote_txn_a[0]);