Add SplicePending and SpiceFailed events

LDK introduced similar events with splicing. SplicePending is largely
informational like ChannelPending. SpliceFailed indicates the used UTXOs
can be reclaimed. This requires UTXO locking, which is not yet
implemented.

Author: jkczyz

src/event.rs

@@ -234,6 +234,28 @@ pub enum Event {
 		/// This will be `None` for events serialized by LDK Node v0.2.1 and prior.
 		reason: Option<ClosureReason>,
 	},
+	/// A channel splice is pending confirmation on-chain.
+	SplicePending {
+		/// The `channel_id` of the channel.
+		channel_id: ChannelId,
+		/// The `user_channel_id` of the channel.
+		user_channel_id: UserChannelId,
+		/// The `node_id` of the channel counterparty.
+		counterparty_node_id: PublicKey,
+		/// The outpoint of the channel's splice funding transaction.
+		new_funding_txo: OutPoint,
+	},
+	/// A channel splice has failed.
+	SpliceFailed {
+		/// The `channel_id` of the channel.
+		channel_id: ChannelId,
+		/// The `user_channel_id` of the channel.
+		user_channel_id: UserChannelId,
+		/// The `node_id` of the channel counterparty.
+		counterparty_node_id: PublicKey,
+		/// The outpoint of the channel's splice funding transaction.
+		abandoned_funding_txo: Option<OutPoint>,
+	},
 }
 
 impl_writeable_tlv_based_enum!(Event,
@@ -291,7 +313,19 @@ impl_writeable_tlv_based_enum!(Event,
 		(10, skimmed_fee_msat, option),
 		(12, claim_from_onchain_tx, required),
 		(14, outbound_amount_forwarded_msat, option),
-	}
+	},
+	(8, SplicePending) => {
+		(1, channel_id, required),
+		(3, counterparty_node_id, required),
+		(5, user_channel_id, required),
+		(7, new_funding_txo, required),
+	},
+	(9, SpliceFailed) => {
+		(1, channel_id, required),
+		(3, counterparty_node_id, required),
+		(5, user_channel_id, required),
+		(7, abandoned_funding_txo, option),
+	},
 );
 
 pub struct EventQueue<L: Deref>
@@ -1611,17 +1645,74 @@ where
 			LdkEvent::FundingTransactionReadyForSigning { .. } => {
 				debug_assert!(false, "We currently don't support interactive-tx, so this event should never be emitted.");
 			},
-			LdkEvent::SplicePending { .. } => {
-				debug_assert!(
-					false,
-					"We currently don't support splicing, so this event should never be emitted."
+			LdkEvent::SplicePending {
+				channel_id,
+				user_channel_id,
+				counterparty_node_id,
+				new_funding_txo,
+				..
+			} => {
+				log_info!(
+					self.logger,
+					"Channel {} with counterparty {} pending splice with funding_txo {}",
+					channel_id,
+					counterparty_node_id,
+					new_funding_txo,
 				);
+
+				let event = Event::SplicePending {
+					channel_id,
+					user_channel_id: UserChannelId(user_channel_id),
+					counterparty_node_id,
+					new_funding_txo,
+				};
+
+				match self.event_queue.add_event(event) {
+					Ok(_) => {},
+					Err(e) => {
+						log_error!(self.logger, "Failed to push to event queue: {}", e);
+						return Err(ReplayEvent());
+					},
+				};
 			},
-			LdkEvent::SpliceFailed { .. } => {
-				debug_assert!(
-					false,
-					"We currently don't support splicing, so this event should never be emitted."
-				);
+			LdkEvent::SpliceFailed {
+				channel_id,
+				user_channel_id,
+				counterparty_node_id,
+				abandoned_funding_txo,
+				..
+			} => {
+				if let Some(funding_txo) = abandoned_funding_txo {
+					log_info!(
+						self.logger,
+						"Channel {} with counterparty {} failed splice with funding_txo {}",
+						channel_id,
+						counterparty_node_id,
+						funding_txo,
+					);
+				} else {
+					log_info!(
+						self.logger,
+						"Channel {} with counterparty {} failed splice",
+						channel_id,
+						counterparty_node_id,
+					);
+				}
+
+				let event = Event::SpliceFailed {
+					channel_id,
+					user_channel_id: UserChannelId(user_channel_id),
+					counterparty_node_id,
+					abandoned_funding_txo,
+				};
+
+				match self.event_queue.add_event(event) {
+					Ok(_) => {},
+					Err(e) => {
+						log_error!(self.logger, "Failed to push to event queue: {}", e);
+						return Err(ReplayEvent());
+					},
+				};
 			},
 		}
 		Ok(())