From 0ad8ab98a97b0a34355b42f0da53eb553fd09c5e Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Thu, 28 Sep 2023 10:24:38 +0930
Subject: [PATCH] lightningd: ensure we *always* watch channel spend.

Now we're not always using the same functions to watch during
dual-funding opening, we need to make sure we're watching the close
(in particular, df close before the opening is confirmed).

So, keep a pointer, and if it's not set in drop_to_chain, set it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 lightningd/channel.c      |  2 ++
 lightningd/channel.h      |  3 +++
 lightningd/peer_control.c | 24 +++++++++++++++++++++---
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lightningd/channel.c b/lightningd/channel.c
index 2dc3755d368d..976d690a2b0e 100644
--- a/lightningd/channel.c
+++ b/lightningd/channel.c
@@ -234,6 +234,7 @@ struct channel *new_unsaved_channel(struct peer *peer,
 	channel->next_index[LOCAL] = 1;
 	channel->next_index[REMOTE] = 1;
 	channel->next_htlc_id = 0;
+	channel->funding_spend_watch = NULL;
 	/* FIXME: remove push when v1 deprecated */
 	channel->push = AMOUNT_MSAT(0);
 	channel->closing_fee_negotiation_step = 50;
@@ -465,6 +466,7 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 	channel->next_htlc_id = next_htlc_id;
 	channel->funding = *funding;
 	channel->funding_sats = funding_sats;
+	channel->funding_spend_watch = NULL;
 	channel->push = push;
 	channel->our_funds = our_funds;
 	channel->remote_channel_ready = remote_channel_ready;
diff --git a/lightningd/channel.h b/lightningd/channel.h
index 0c707aef3c77..6027b57565a5 100644
--- a/lightningd/channel.h
+++ b/lightningd/channel.h
@@ -155,6 +155,9 @@ struct channel {
 	struct bitcoin_outpoint funding;
 	struct amount_sat funding_sats;
 
+	/* Watch we have on funding output. */
+	struct txowatch *funding_spend_watch;
+
 	/* Our original funds, in funding amount */
 	struct amount_sat our_funds;
 
diff --git a/lightningd/peer_control.c b/lightningd/peer_control.c
index 9c84fc709dc0..172aa03b550c 100644
--- a/lightningd/peer_control.c
+++ b/lightningd/peer_control.c
@@ -311,12 +311,28 @@ static struct bitcoin_tx *sign_and_send_last(const tal_t *ctx,
 	return tx;
 }
 
+/* FIXME: reorder! */
+static enum watch_result funding_spent(struct channel *channel,
+				       const struct bitcoin_tx *tx,
+				       size_t inputnum UNUSED,
+				       const struct block *block);
+
 void drop_to_chain(struct lightningd *ld, struct channel *channel,
 		   bool cooperative)
 {
 	struct channel_inflight *inflight;
 	const char *cmd_id;
 
+	/* If we're not already (e.g. close before channel fully open),
+	 * make sure we're watching for the funding spend */
+	if (!channel->funding_spend_watch) {
+		log_debug(channel->log, "Adding funding_spend_watch");
+		channel->funding_spend_watch = watch_txo(channel,
+							 ld->topology, channel,
+							 &channel->funding,
+							 funding_spent);
+	}
+
 	/* If this was triggered by a close command, get a copy of the cmd id */
 	cmd_id = cmd_id_from_close_command(tmpctx, ld, channel);
 
@@ -2108,9 +2124,11 @@ void channel_watch_funding(struct lightningd *ld, struct channel *channel)
 		type_to_string(tmpctx, struct bitcoin_txid, &channel->funding.txid));
 	watch_txid(channel, ld->topology,
 		   &channel->funding.txid, funding_depth_cb, channel);
-	watch_txo(channel, ld->topology, channel,
-		  &channel->funding,
-		  funding_spent);
+
+	tal_free(channel->funding_spend_watch);
+	channel->funding_spend_watch = watch_txo(channel, ld->topology, channel,
+						 &channel->funding,
+						 funding_spent);
 	channel_watch_wrong_funding(ld, channel);
 }