From d4408a9ae044133d779e85caae56d7e0db7ab9cd Mon Sep 17 00:00:00 2001
From: niftynei <niftynei@gmail.com>
Date: Tue, 6 Jul 2021 12:21:43 -0500
Subject: [PATCH] channel-leases: add lease fee to accepter's funding earlier
 up

We need the 'actual' accepter's funding for the reserve calculations,
which includes the lease fee that the opener is paying them, so we
calculate it before doing all that jazz.

However, we MUST send the actual "on paper" (e.g. without lease fee)
amount to the peer in accept_channel2, so we stash the original amount
and send it.
---
 openingd/dualopend.c | 90 +++++++++++++++++++++++---------------------
 1 file changed, 47 insertions(+), 43 deletions(-)

diff --git a/openingd/dualopend.c b/openingd/dualopend.c
index a8ae795ac..f9fac9630 100644
--- a/openingd/dualopend.c
+++ b/openingd/dualopend.c
@@ -2027,7 +2027,7 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 	struct channel_id cid, full_cid;
 	char *err_reason;
 	u8 *msg;
-	struct amount_sat total, requested_amt, lease_fee;
+	struct amount_sat total, requested_amt, lease_fee, our_accept;
 	enum dualopend_wire msg_type;
 	struct tx_state *tx_state = state->tx_state;
 
@@ -2175,6 +2175,50 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 		return;
 	}
 
+	/* This we bump the accepter_funding iff there's a lease,
+	 * so we stash this here so we tell our peer the right amount */
+	our_accept = tx_state->accepter_funding;
+
+	/* Add our fee to our amount now */
+	if (tx_state->rates) {
+		tx_state->lease_expiry
+			= tx_state->blockheight + LEASE_RATE_DURATION;
+
+		/* BOLT- #2:
+		 * The lease fee is added to the accepter's balance
+		 * in a channel, in addition to the `funding_satoshi`
+		 * that they are contributing. The channel initiator
+		 * must contribute enough funds to cover
+		 * `open_channel2`.`funding_satoshis`, the lease fee,
+		 * and their tx weight * `funding_feerate_perkw` / 1000.
+		 */
+		if (!lease_rates_calc_fee(tx_state->rates,
+					  tx_state->accepter_funding,
+					  requested_amt,
+					  tx_state->feerate_per_kw_funding,
+					  &lease_fee))
+			negotiation_failed(state,
+					   "Unable to calculate lease fee");
+
+		/* Add it to the accepter's total */
+		if (!amount_sat_add(&tx_state->accepter_funding,
+				    tx_state->accepter_funding, lease_fee))
+
+			negotiation_failed(state,
+					   "Unable to add accepter's funding"
+					   " and channel lease fee (%s + %s)",
+					   type_to_string(tmpctx,
+							  struct amount_sat,
+							  &tx_state->accepter_funding),
+					   type_to_string(tmpctx,
+							  struct amount_sat,
+							  &lease_fee));
+
+	} else {
+		tx_state->lease_expiry = 0;
+		lease_fee = AMOUNT_SAT(0);
+	}
+
 	/* Check that total funding doesn't overflow */
 	if (!amount_sat_add(&total, tx_state->opener_funding,
 			    tx_state->accepter_funding))
@@ -2253,7 +2297,8 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 
 
 	msg = towire_accept_channel2(tmpctx, &state->channel_id,
-				     tx_state->accepter_funding,
+				     /* Our amount w/o the lease fee */
+				     our_accept,
 				     tx_state->localconf.dust_limit,
 				     tx_state->localconf.max_htlc_value_in_flight,
 				     tx_state->localconf.htlc_minimum,
@@ -2276,47 +2321,6 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 	sync_crypto_write(state->pps, msg);
 	peer_billboard(false, "channel open: accept sent, waiting for reply");
 
-	/* Add our fee to our amount now */
-	if (tx_state->rates) {
-		tx_state->lease_expiry
-			= tx_state->blockheight + LEASE_RATE_DURATION;
-
-		/* BOLT- #2:
-		 * The lease fee is added to the accepter's balance
-		 * in a channel, in addition to the `funding_satoshi`
-		 * that they are contributing. The channel initiator
-		 * must contribute enough funds to cover
-		 * `open_channel2`.`funding_satoshis`, the lease fee,
-		 * and their tx weight * `funding_feerate_perkw` / 1000.
-		 */
-		if (!lease_rates_calc_fee(tx_state->rates,
-					  tx_state->accepter_funding,
-					  requested_amt,
-					  tx_state->feerate_per_kw_funding,
-					  &lease_fee))
-			negotiation_failed(state,
-					   "Unable to calculate lease fee");
-
-		/* Add it to the accepter's total */
-		if (!amount_sat_add(&tx_state->accepter_funding,
-				    tx_state->accepter_funding, lease_fee)) {
-
-			negotiation_failed(state,
-					   "Unable to add accepter's funding"
-					   " and channel lease fee (%s + %s)",
-					   type_to_string(tmpctx,
-							  struct amount_sat,
-							  &tx_state->accepter_funding),
-					   type_to_string(tmpctx,
-							  struct amount_sat,
-							  &lease_fee));
-			return;
-		}
-	} else {
-		tx_state->lease_expiry = 0;
-		lease_fee = AMOUNT_SAT(0);
-	}
-
 	/* This is unused in this flow. We re-use
 	 * the wire method between accepter + opener, so we set it
 	 * to an invalid number, 1 (initiator sets; valid is even) */