event: store the outpoint when is_manual_broadcast

With [1], it's possible to specify `manual_broadcast` for
the channel funding transaction. When `is_manual_broadcast` is
set to true, the transaction in the `DiscardFunding` event is
replaced with a dummy empty transaction.

This commit checks if `is_manual_broadcast` is true and
stores the funding OutPoint in the DiscardFunding event instead.

[1] #3024

Link: #3164
Suggested-by: TheBlueMatt
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

Author: vincenzopalazzo

lightning/src/events/mod.rs

@@ -22,7 +22,7 @@ use crate::blinded_path::message::OffersContext;
 use crate::blinded_path::payment::{Bolt12OfferContext, Bolt12RefundContext, PaymentContext, PaymentContextRef};
 use crate::chain::transaction;
 use crate::ln::channelmanager::{InterceptId, PaymentId, RecipientOnionFields};
-use crate::ln::channel::FUNDING_CONF_DEADLINE_BLOCKS;
+use crate::ln::channel::{FundingInfo, FUNDING_CONF_DEADLINE_BLOCKS};
 use crate::ln::features::ChannelTypeFeatures;
 use crate::ln::msgs;
 use crate::ln::types::{ChannelId, PaymentPreimage, PaymentHash, PaymentSecret};
@@ -1257,7 +1257,7 @@ pub enum Event {
 		/// The channel_id of the channel which has been closed.
 		channel_id: ChannelId,
 		/// The full transaction received from the user
-		transaction: Transaction
+		funding_info: FundingInfo,
 	},
 	/// Indicates a request to open a new channel by a peer.
 	///
@@ -1541,7 +1541,7 @@ impl Writeable for Event {
 					(9, channel_funding_txo, option),
 				});
 			},
-			&Event::DiscardFunding { ref channel_id, ref transaction } => {
+			&Event::DiscardFunding { ref channel_id, funding_info: ref transaction } => {
 				11u8.write(writer)?;
 				write_tlv_fields!(writer, {
 					(0, channel_id, required),
@@ -1929,7 +1929,9 @@ impl MaybeReadable for Event {
 						(0, channel_id, required),
 						(2, transaction, required),
 					});
-					Ok(Some(Event::DiscardFunding { channel_id, transaction } ))
+					// FIXME: what it is going on here? we are sure taht we need an tx? or we can just create a simple
+					// outpoint?
+					Ok(Some(Event::DiscardFunding { channel_id, funding_info: transaction.into() } ))
 				};
 				f()
 			},

lightning/src/ln/channel.rs

@@ -918,6 +918,36 @@ pub(super) struct ReestablishResponses {
 	pub shutdown_msg: Option<msgs::Shutdown>,
 }
 
+// FIXME(vincenzopalazzo): There is a better plave where to expose this type?
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum FundingInfo {
+	Tx(Transaction),
+	OutPoint(OutPoint),
+}
+
+impl Writeable for FundingInfo {
+ fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+	 match self {
+		 Self::OutPoint(o) => o.write(writer),
+		 Self::Tx(tx) => tx.write(writer),
+	 }
+ }
+}
+
+impl From<Transaction> for FundingInfo {
+	fn from(value: Transaction) -> Self {
+		Self::Tx(value)
+	}
+}
+
+impl From<OutPoint> for FundingInfo {
+	fn from(value: OutPoint) -> Self {
+		Self::OutPoint(value)
+	}
+}
+
+
+
 /// The result of a shutdown that should be handled.
 #[must_use]
 pub(crate) struct ShutdownResult {

lightning/src/ln/channelmanager.rs

@@ -47,7 +47,7 @@ use crate::events::{Event, EventHandler, EventsProvider, MessageSendEvent, Messa
 // construct one themselves.
 use crate::ln::inbound_payment;
 use crate::ln::types::{ChannelId, PaymentHash, PaymentPreimage, PaymentSecret};
-use crate::ln::channel::{self, Channel, ChannelPhase, ChannelContext, ChannelError, ChannelUpdateStatus, ShutdownResult, UnfundedChannelContext, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel, WithChannelContext};
+use crate::ln::channel::{self, Channel, ChannelContext, ChannelError, ChannelPhase, ChannelUpdateStatus, FundingInfo, InboundV1Channel, OutboundV1Channel, ShutdownResult, UnfundedChannelContext, UpdateFulfillCommitFetch, WithChannelContext};
 use crate::ln::channel_state::ChannelDetails;
 use crate::ln::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
 #[cfg(any(feature = "_test_utils", test))]
@@ -3509,6 +3509,7 @@ where
 			let _ = self.chain_monitor.update_channel(funding_txo, &monitor_update);
 		}
 		let mut shutdown_results = Vec::new();
+		let mut is_manual_broadcast = false;
 		if let Some(txid) = shutdown_res.unbroadcasted_batch_funding_txid {
 			let mut funding_batch_states = self.funding_batch_states.lock().unwrap();
 			let affected_channels = funding_batch_states.remove(&txid).into_iter().flatten();
@@ -3518,6 +3519,10 @@ where
 				if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
 					let mut peer_state = peer_state_mutex.lock().unwrap();
 					if let Some(mut chan) = peer_state.channel_by_id.remove(&channel_id) {
+						// We override the previous value, so we could change from true -> false,
+						// but this is fine because if a channel has manual_broadcast set to false
+						// we should choose the safier condition.
+						is_manual_broadcast = chan.context().is_manual_broadcast();
 						update_maps_on_chan_removal!(self, &chan.context());
 						shutdown_results.push(chan.context_mut().force_shutdown(false, ClosureReason::FundingBatchClosure));
 					}
@@ -3541,9 +3546,14 @@ where
 				channel_funding_txo: shutdown_res.channel_funding_txo,
 			}, None));
 
-			if let Some(transaction) = shutdown_res.unbroadcasted_funding_tx {
+			let funding_info = if is_manual_broadcast {
+				shutdown_res.channel_funding_txo.map(FundingInfo::from)
+			} else {
+				shutdown_res.unbroadcasted_funding_tx.map(FundingInfo::from)
+			};
+			if let Some(funding_info) = funding_info {
 				pending_events.push_back((events::Event::DiscardFunding {
-					channel_id: shutdown_res.channel_id, transaction
+					channel_id: shutdown_res.channel_id, funding_info
 				}, None));
 			}
 		}