From 239ed54b8b700c5879e1274e950b1d370d8362ff Mon Sep 17 00:00:00 2001
From: Alec Chen <alecchendev@gmail.com>
Date: Thu, 6 Jun 2024 18:15:30 -0500
Subject: [PATCH] Handle fallible commitment point when getting channel_ready

---
 lightning/src/ln/channel.rs | 38 +++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 4faae954423..776cb8943b5 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -1280,6 +1280,9 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
 	/// [`msgs::FundingCreated`] or [`msgs::FundingSigned`] depending on if this channel is
 	/// outbound or inbound.
 	signer_pending_funding: bool,
+	/// Similar to [`Self::signer_pending_commitment_update`] but we're waiting to send a
+	/// [`msgs::ChannelReady`].
+	signer_pending_channel_ready: bool,
 
 	// pending_update_fee is filled when sending and receiving update_fee.
 	//
@@ -1741,6 +1744,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 			signer_pending_revoke_and_ack: false,
 			signer_pending_commitment_update: false,
 			signer_pending_funding: false,
+			signer_pending_channel_ready: false,
 
 
 			#[cfg(debug_assertions)]
@@ -1970,6 +1974,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 			signer_pending_revoke_and_ack: false,
 			signer_pending_commitment_update: false,
 			signer_pending_funding: false,
+			signer_pending_channel_ready: false,
 
 			// We'll add our counterparty's `funding_satoshis` to these max commitment output assertions
 			// when we receive `accept_channel2`.
@@ -5339,7 +5344,7 @@ impl<SP: Deref> Channel<SP> where
 			assert!(!self.context.is_outbound() || self.context.minimum_depth == Some(0),
 				"Funding transaction broadcast by the local client before it should have - LDK didn't do it!");
 			self.context.monitor_pending_channel_ready = false;
-			Some(self.get_channel_ready())
+			self.get_channel_ready(logger)
 		} else { None };
 
 		let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block_height, logger);
@@ -5708,7 +5713,7 @@ impl<SP: Deref> Channel<SP> where
 
 			// We have OurChannelReady set!
 			return Ok(ReestablishResponses {
-				channel_ready: Some(self.get_channel_ready()),
+				channel_ready: self.get_channel_ready(logger),
 				raa: None, commitment_update: None,
 				order: RAACommitmentOrder::CommitmentFirst,
 				shutdown_msg, announcement_sigs,
@@ -5747,7 +5752,7 @@ impl<SP: Deref> Channel<SP> where
 
 		let channel_ready = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.context.holder_commitment_point.transaction_number() == 1 {
 			// We should never have to worry about MonitorUpdateInProgress resending ChannelReady
-			Some(self.get_channel_ready())
+			self.get_channel_ready(logger)
 		} else { None };
 
 		if msg.next_local_commitment_number == next_counterparty_commitment_number {
@@ -6654,19 +6659,23 @@ impl<SP: Deref> Channel<SP> where
 			return None;
 		}
 
-		// TODO: when get_per_commiment_point becomes async, check if the point is
-		// available, if not, set signer_pending_channel_ready and return None
-
-		Some(self.get_channel_ready())
+		self.get_channel_ready(logger)
 	}
 
-	fn get_channel_ready(&self) -> msgs::ChannelReady {
-		debug_assert!(self.context.holder_commitment_point.is_available());
-		msgs::ChannelReady {
-			channel_id: self.context.channel_id(),
-			next_per_commitment_point: self.context.holder_commitment_point.current_point()
-				.expect("TODO"),
-			short_channel_id_alias: Some(self.context.outbound_scid_alias),
+	fn get_channel_ready<L: Deref>(&mut self, logger: &L) -> Option<msgs::ChannelReady>
+	where L::Target: Logger
+	{
+		if let HolderCommitmentPoint::Available { current, .. } = self.context.holder_commitment_point {
+			self.context.signer_pending_channel_ready = false;
+			Some(msgs::ChannelReady {
+				channel_id: self.context.channel_id(),
+				next_per_commitment_point: current,
+				short_channel_id_alias: Some(self.context.outbound_scid_alias),
+			})
+		} else {
+			log_debug!(logger, "Not producing channel_ready: the holder commitment point is not available.");
+			self.context.signer_pending_channel_ready = true;
+			None
 		}
 	}
 
@@ -9486,6 +9495,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
 				signer_pending_revoke_and_ack: false,
 				signer_pending_commitment_update: false,
 				signer_pending_funding: false,
+				signer_pending_channel_ready: false,
 
 				pending_update_fee,
 				holding_cell_update_fee,