Finetune balance check, use expected balance

Author: optout21

lightning/src/ln/channel.rs

@@ -3423,7 +3423,10 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
 	/// The channel value is an input as opposed to using from self, so that this can be used in case of splicing
 	/// to checks with new channel value (before being comitted to it).
 	#[cfg(any(dual_funding, splicing))]
-	pub fn check_balance_meets_reserve_requirements(&self, channel_value: u64, balance: u64) -> Result<(), ChannelError> {
+	pub fn check_balance_meets_reserve_requirements(&self, balance: u64, channel_value: u64) -> Result<(), ChannelError> {
+		if balance == 0 {
+			return Ok(());
+		}
 		let holder_selected_channel_reserve_satoshis = get_v2_channel_reserve_satoshis(
 			channel_value, self.holder_dust_limit_satoshis);
 		if balance < holder_selected_channel_reserve_satoshis {
@@ -7485,9 +7488,11 @@ impl<SP: Deref> Channel<SP> where
 
 	/// Handle splice_init
 	#[cfg(splicing)]
-	pub fn splice_init(
-		&mut self, their_funding_contribution_satoshis: i64, our_funding_contribution_satoshis: i64,
-	) -> Result<msgs::SpliceAck, ChannelError> {
+	pub fn splice_init(&mut self, msg: &msgs::SpliceInit) -> Result<msgs::SpliceAck, ChannelError> {
+		let their_funding_contribution_satoshis = msg.funding_contribution_satoshis;
+		// TODO(splicing): Currently not possible to contribute on the splicing-acceptor side
+		let our_funding_contribution_satoshis = 0i64;
+
 		// Check if a splice has been initiated already.
 		// Note: this could be handled more nicely, and support multiple outstanding splice's, the incoming splice_ack matters anyways.
 		if let Some(splice_info) = &self.context.pending_splice_pre {
@@ -7520,11 +7525,12 @@ impl<SP: Deref> Channel<SP> where
 		}
 
 		let post_channel_value = PendingSpliceInfoPre::compute_post_value(pre_channel_value, their_funding_contribution_satoshis, our_funding_contribution_satoshis);
-
+		let post_balance = PendingSpliceInfoPre::add_checked(self.context.value_to_self_msat, our_funding_contribution_satoshis);
 		// Early check for reserve requirement, assuming maximum balance of full channel value
 		// This will also be checked later at tx_complete
-		let _res = self.context.check_balance_meets_reserve_requirements(post_channel_value, post_channel_value)?;
+		let _res = self.context.check_balance_meets_reserve_requirements(post_balance, post_channel_value)?;
 
+		// TODO(splicing): Store msg.funding_pubkey
 		// TODO(splicing): Apply start of splice (splice_start)
 
 		let splice_ack_msg = self.context.get_splice_ack(our_funding_contribution_satoshis);
@@ -7534,22 +7540,24 @@ impl<SP: Deref> Channel<SP> where
 
 	/// Handle splice_ack
 	#[cfg(splicing)]
-	pub fn splice_ack(
-		&mut self, their_funding_contribution_satoshis: i64,
-	) -> Result<(), ChannelError> {
+	pub fn splice_ack(&mut self, msg: &msgs::SpliceAck) -> Result<(), ChannelError> {
+		let their_funding_contribution_satoshis = msg.funding_contribution_satoshis;
+
 		// check if splice is pending
 		let pending_splice = if let Some(pending_splice) = &self.context.pending_splice_pre {
 			pending_splice
 		} else {
 			return Err(ChannelError::Warn(format!("Channel is not in pending splice")));
 		};
 
-		let pre_channel_value = self.context.get_value_satoshis();
-		let post_channel_value = PendingSpliceInfoPre::compute_post_value(pre_channel_value, pending_splice.our_funding_contribution, their_funding_contribution_satoshis);
+		let our_funding_contribution = pending_splice.our_funding_contribution;
 
+		let pre_channel_value = self.context.get_value_satoshis();
+		let post_channel_value = PendingSpliceInfoPre::compute_post_value(pre_channel_value, our_funding_contribution, their_funding_contribution_satoshis);
+		let post_balance = PendingSpliceInfoPre::add_checked(self.context.value_to_self_msat, our_funding_contribution);
 		// Early check for reserve requirement, assuming maximum balance of full channel value
 		// This will also be checked later at tx_complete
-		let _res = self.context.check_balance_meets_reserve_requirements(post_channel_value, post_channel_value)?;
+		let _res = self.context.check_balance_meets_reserve_requirements(post_balance, post_channel_value)?;
 		Ok(())
 	}
 

lightning/src/ln/channelmanager.rs

@@ -9002,8 +9002,6 @@ where
 		let mut peer_state_lock = peer_state_mutex.lock().unwrap();
 		let peer_state = &mut *peer_state_lock;
 
-		let our_funding_contribution = 0i64;
-
 		// Look for the channel
 		match peer_state.channel_by_id.entry(msg.channel_id) {
 			hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!(
@@ -9012,7 +9010,7 @@ where
 				), msg.channel_id)),
 			hash_map::Entry::Occupied(mut chan_entry) => {
 				if let ChannelPhase::Funded(chan) = chan_entry.get_mut() {
-					match chan.splice_init(msg.funding_contribution_satoshis, our_funding_contribution) {
+					match chan.splice_init(msg) {
 						Ok(splice_ack_msg) => {
 							peer_state.pending_msg_events.push(events::MessageSendEvent::SendSpliceAck {
 								node_id: *counterparty_node_id,
@@ -9060,7 +9058,7 @@ where
 				), msg.channel_id)),
 			hash_map::Entry::Occupied(mut chan) => {
 				if let ChannelPhase::Funded(chan) = chan.get_mut() {
-					match chan.splice_ack(msg.funding_contribution_satoshis) {
+					match chan.splice_ack(msg) {
 						Ok(_) => {}
 						Err(err) => {
 							return Err(MsgHandleErrInternal::from_chan_no_close(err, msg.channel_id));