From a0ab812da911cb6cdeb554071f5aa122669252f5 Mon Sep 17 00:00:00 2001 From: Antoine Riard Date: Tue, 19 Oct 2021 13:29:50 -0400 Subject: [PATCH] Introduce new helper commit_tx_fee_sat --- lightning/src/ln/channel.rs | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index 7883d7b29..5bd47c329 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -1183,11 +1183,11 @@ impl Channel { broadcaster_max_commitment_tx_output.1 = cmp::max(broadcaster_max_commitment_tx_output.1, value_to_remote_msat as u64); } - let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (included_non_dust_htlcs.len() as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000; + let total_fee_sat = Channel::::commit_tx_fee_sat(feerate_per_kw, included_non_dust_htlcs.len()); let (value_to_self, value_to_remote) = if self.is_outbound() { - (value_to_self_msat / 1000 - total_fee as i64, value_to_remote_msat / 1000) + (value_to_self_msat / 1000 - total_fee_sat as i64, value_to_remote_msat / 1000) } else { - (value_to_self_msat / 1000, value_to_remote_msat / 1000 - total_fee as i64) + (value_to_self_msat / 1000, value_to_remote_msat / 1000 - total_fee_sat as i64) }; let mut value_to_a = if local { value_to_self } else { value_to_remote }; @@ -1995,7 +1995,7 @@ impl Channel { self.counterparty_selected_channel_reserve_satoshis) } - // Get the fee cost of a commitment tx with a given number of HTLC outputs. + // Get the fee cost in MSATS of a commitment tx with a given number of HTLC outputs. // Note that num_htlcs should not include dust HTLCs. fn commit_tx_fee_msat(&self, num_htlcs: usize) -> u64 { // Note that we need to divide before multiplying to round properly, @@ -2003,6 +2003,13 @@ impl Channel { (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) * self.feerate_per_kw as u64 / 1000 * 1000 } + // Get the fee cost in SATS of a commitment tx with a given number of HTLC outputs. + // Note that num_htlcs should not include dust HTLCs. + #[inline] + fn commit_tx_fee_sat(feerate_per_kw: u32, num_htlcs: usize) -> u64 { + feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000 + } + // Get the commitment tx fee for the local's (i.e. our) next commitment transaction based on the // number of pending HTLCs that are on track to be in our next commitment tx, plus an additional // HTLC if `fee_spike_buffer_htlc` is Some, plus a new HTLC given by `new_htlc_amount`. Dust HTLCs @@ -2426,10 +2433,10 @@ impl Channel { update_state == FeeUpdateState::RemoteAnnounced } else { false }; if update_fee { debug_assert!(!self.is_outbound()); } - let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000; + let total_fee_sat = Channel::::commit_tx_fee_sat(feerate_per_kw, num_htlcs); if update_fee { let counterparty_reserve_we_require = Channel::::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis); - if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee + counterparty_reserve_we_require { + if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee_sat + counterparty_reserve_we_require { return Err((None, ChannelError::Close("Funding remote cannot afford proposed new fee".to_owned()))); } } @@ -2445,7 +2452,7 @@ impl Channel { && info.next_holder_htlc_id == self.next_holder_htlc_id && info.next_counterparty_htlc_id == self.next_counterparty_htlc_id && info.feerate == self.feerate_per_kw { - assert_eq!(total_fee, info.fee / 1000); + assert_eq!(total_fee_sat, info.fee / 1000); } } } -- 2.39.5