Don't rebroadcast redundant closing TX upon restart

lightning/src/chain/channelmonitor.rs

@@ -1206,6 +1206,22 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitor<Signer> {
 		self.inner.lock().unwrap().broadcast_latest_holder_commitment_txn(broadcaster, logger);
 	}
 
+	pub(crate) fn broadcast_latest_holder_commitment_txn_if_unspent<B: Deref, L: Deref>(
+		&self,
+		broadcaster: &B,
+		logger: &L,
+	) where
+		B::Target: BroadcasterInterface,
+		L::Target: Logger,
+	{
+		let mut locked_inner = self.inner.lock().unwrap();
+		if !locked_inner.detected_funding_spend() {
+			log_info!(logger, "Broadcasting latest holder commitment transaction for channel {}",
+				log_bytes!(locked_inner.get_funding_txo().0.to_channel_id()));
+			locked_inner.broadcast_latest_holder_commitment_txn(broadcaster, logger);
+		}
+	}
+
 	/// Updates a ChannelMonitor on the basis of some new information provided by the Channel
 	/// itself.
 	///
@@ -2275,12 +2291,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 						// There's no need to broadcast our commitment transaction if we've seen one
 						// confirmed (even with 1 confirmation) as it'll be rejected as
 						// duplicate/conflicting.
-						let detected_funding_spend = self.funding_spend_confirmed.is_some() ||
-							self.onchain_events_awaiting_threshold_conf.iter().find(|event| match event.event {
-								OnchainEvent::FundingSpendConfirmation { .. } => true,
-								_ => false,
-							}).is_some();
-						if detected_funding_spend {
+						if self.detected_funding_spend() {
 							continue;
 						}
 						self.broadcast_latest_holder_commitment_txn(broadcaster, logger);
@@ -2338,6 +2349,15 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		&self.funding_info
 	}
 
+	pub fn detected_funding_spend(&self) -> bool {
+		self.funding_spend_confirmed.is_some() ||
+		self.onchain_events_awaiting_threshold_conf
+			.iter().find(|event| match event.event {
+				OnchainEvent::FundingSpendConfirmation { .. } => true,
+				_ => false,
+		}).is_some()
+	}
+
 	pub fn get_outputs_to_watch(&self) -> &HashMap<Txid, Vec<(u32, Script)>> {
 		// If we've detected a counterparty commitment tx on chain, we must include it in the set
 		// of outputs to watch for spends of, otherwise we're likely to lose user funds. Because

lightning/src/ln/channelmanager.rs

@@ -7209,8 +7209,10 @@ where
 
 		for (funding_txo, monitor) in args.channel_monitors.iter_mut() {
 			if !funding_txo_set.contains(funding_txo) {
-				log_info!(args.logger, "Broadcasting latest holder commitment transaction for closed channel {}", log_bytes!(funding_txo.to_channel_id()));
-				monitor.broadcast_latest_holder_commitment_txn(&args.tx_broadcaster, &args.logger);
+				// There's no need to broadcast our commitment transaction if
+				// we've seen one confirmed (even with 1 confirmation) as it'll
+				// be rejected as duplicate/conflicting.
+				monitor.broadcast_latest_holder_commitment_txn_if_unspent(&args.tx_broadcaster, &args.logger);
 			}
 		}