splice: Update our_funds during splice_lock

The value of `our_funds` inlightningd is the funds added to the channel during creation. Splicing is a quasi-creation event. This change makes our pending funds be considered funding funds at the moment of splice confirmation.

Changelog-None

Author: ddustin

lightningd/channel_control.c

@@ -1125,7 +1125,7 @@ static void handle_peer_splice_locked(struct channel *channel, const u8 *msg)
 	wallet_htlcsigs_confirm_inflight(channel->peer->ld->wallet, channel,
 					 &inflight->funding->outpoint);
 
-	update_channel_from_inflight(channel->peer->ld, channel, inflight);
+	update_channel_from_inflight(channel->peer->ld, channel, inflight, true);
 
 	/* Remember that we got the lockin */
 	wallet_channel_save(channel->peer->ld->wallet, channel);

lightningd/dual_open_control.c

@@ -1055,7 +1055,8 @@ static enum watch_result opening_depth_cb(struct lightningd *ld,
 				   &inflight->channel->peer->id);
 
 	if (depth >= inflight->channel->minimum_depth)
-		update_channel_from_inflight(ld, inflight->channel, inflight);
+		update_channel_from_inflight(ld, inflight->channel, inflight,
+					     false);
 
 	dualopend_tell_depth(inflight->channel, txid, depth);
 

lightningd/peer_control.c

@@ -361,7 +361,7 @@ static enum watch_result closed_inflight_depth_cb(struct lightningd *ld,
 		return KEEP_WATCHING;
 
 	/* This is now the main tx. */
-	update_channel_from_inflight(ld, inflight->channel, inflight);
+	update_channel_from_inflight(ld, inflight->channel, inflight, false);
 	channel_fail_saw_onchain(inflight->channel,
 				 REASON_UNKNOWN,
 				 tx,
@@ -2074,13 +2074,19 @@ void peer_disconnect_done(struct lightningd *ld, const u8 *msg)
 
 void update_channel_from_inflight(struct lightningd *ld,
 				  struct channel *channel,
-				  const struct channel_inflight *inflight)
+				  const struct channel_inflight *inflight,
+				  bool is_splice)
 {
 	channel->funding = inflight->funding->outpoint;
 	channel->funding_sats = inflight->funding->total_funds;
 
 	channel->our_funds = inflight->funding->our_funds;
 
+	/* At this point, our_msat *becomes* our_funds because the splice
+	 * confirms. Any excess millisats stay in our_msats */
+	if (is_splice)
+		channel->our_funds = amount_msat_to_sat_round_down(channel->our_msat);
+
 	if (!amount_sat_add_sat_s64(&channel->our_funds, channel->our_funds,
 				    inflight->funding->splice_amnt)) {
 

lightningd/peer_control.h

@@ -128,7 +128,8 @@ void drop_to_chain(struct lightningd *ld, struct channel *channel,
 
 void update_channel_from_inflight(struct lightningd *ld,
 				  struct channel *channel,
-				  const struct channel_inflight *inflight);
+				  const struct channel_inflight *inflight,
+				  bool is_splice);
 
 void channel_watch_funding(struct lightningd *ld, struct channel *channel);