From ab11f450b67628284e80c28bce2b7d1e9033e97e Mon Sep 17 00:00:00 2001 From: Antoine Riard Date: Sat, 21 Aug 2021 18:52:05 -0400 Subject: [PATCH] Check we won't overflow `max_dust_htlc_exposure_msat` at outbound feerate update --- lightning/src/ln/channel.rs | 59 +++++++++++++++++++++++-------------- 1 file changed, 37 insertions(+), 22 deletions(-) diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index d0e6931f3..88007e3bc 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -1998,7 +1998,7 @@ impl Channel { } /// Returns a HTLCStats about inbound pending htlcs - fn get_inbound_pending_htlc_stats(&self) -> HTLCStats { + fn get_inbound_pending_htlc_stats(&self, outbound_feerate_update: Option) -> HTLCStats { let mut stats = HTLCStats { pending_htlcs: self.pending_inbound_htlcs.len() as u32, pending_htlcs_value_msat: 0, @@ -2007,8 +2007,8 @@ impl Channel { holding_cell_msat: 0, }; - let counterparty_dust_limit_timeout_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; - let holder_dust_limit_success_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; + let counterparty_dust_limit_timeout_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; + let holder_dust_limit_success_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; for ref htlc in self.pending_inbound_htlcs.iter() { stats.pending_htlcs_value_msat += htlc.amount_msat; if htlc.amount_msat / 1000 < counterparty_dust_limit_timeout_sat { @@ -2022,7 +2022,7 @@ impl Channel { } /// Returns a HTLCStats about pending outbound htlcs, *including* pending adds in our holding cell. - fn get_outbound_pending_htlc_stats(&self) -> HTLCStats { + fn get_outbound_pending_htlc_stats(&self, outbound_feerate_update: Option) -> HTLCStats { let mut stats = HTLCStats { pending_htlcs: self.pending_outbound_htlcs.len() as u32, pending_htlcs_value_msat: 0, @@ -2031,8 +2031,8 @@ impl Channel { holding_cell_msat: 0, }; - let counterparty_dust_limit_success_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; - let holder_dust_limit_timeout_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; + let counterparty_dust_limit_success_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; + let holder_dust_limit_timeout_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; for ref htlc in self.pending_outbound_htlcs.iter() { stats.pending_htlcs_value_msat += htlc.amount_msat; if htlc.amount_msat / 1000 < counterparty_dust_limit_success_sat { @@ -2068,11 +2068,11 @@ impl Channel { ( cmp::max(self.channel_value_satoshis as i64 * 1000 - self.value_to_self_msat as i64 - - self.get_inbound_pending_htlc_stats().pending_htlcs_value_msat as i64 + - self.get_inbound_pending_htlc_stats(None).pending_htlcs_value_msat as i64 - Self::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64 * 1000, 0) as u64, cmp::max(self.value_to_self_msat as i64 - - self.get_outbound_pending_htlc_stats().pending_htlcs_value_msat as i64 + - self.get_outbound_pending_htlc_stats(None).pending_htlcs_value_msat as i64 - self.counterparty_selected_channel_reserve_satoshis.unwrap_or(0) as i64 * 1000, 0) as u64 ) @@ -2291,8 +2291,8 @@ impl Channel { return Err(ChannelError::Close(format!("Remote side tried to send less than our minimum HTLC value. Lower limit: ({}). Actual: ({})", self.holder_htlc_minimum_msat, msg.amount_msat))); } - let inbound_stats = self.get_inbound_pending_htlc_stats(); - let outbound_stats = self.get_outbound_pending_htlc_stats(); + let inbound_stats = self.get_inbound_pending_htlc_stats(None); + let outbound_stats = self.get_outbound_pending_htlc_stats(None); if inbound_stats.pending_htlcs + 1 > OUR_MAX_HTLCS as u32 { return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", OUR_MAX_HTLCS))); } @@ -2321,7 +2321,7 @@ impl Channel { } } - let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; + let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; if msg.amount_msat / 1000 < exposure_dust_limit_timeout_sats { let on_counterparty_tx_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + msg.amount_msat; if on_counterparty_tx_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() { @@ -2331,7 +2331,7 @@ impl Channel { } } - let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; + let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; if msg.amount_msat / 1000 < exposure_dust_limit_success_sats { let on_holder_tx_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + msg.amount_msat; if on_holder_tx_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() { @@ -3080,8 +3080,8 @@ impl Channel { } // Before proposing a feerate update, check that we can actually afford the new fee. - let inbound_stats = self.get_inbound_pending_htlc_stats(); - let outbound_stats = self.get_outbound_pending_htlc_stats(); + let inbound_stats = self.get_inbound_pending_htlc_stats(Some(feerate_per_kw)); + let outbound_stats = self.get_outbound_pending_htlc_stats(Some(feerate_per_kw)); let keys = if let Ok(keys) = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number) { keys } else { return None; }; let (_, _, num_htlcs, _, holder_balance_msat, _) = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger); let total_fee_sat = Channel::::commit_tx_fee_sat(feerate_per_kw, num_htlcs + CONCURRENT_INBOUND_HTLC_FEE_BUFFER as usize); @@ -3092,6 +3092,18 @@ impl Channel { return None; } + // Note, we evaluate pending htlc "preemptive" trimmed-to-dust threshold at the proposed `feerate_per_kw`. + let holder_tx_dust_exposure = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat; + let counterparty_tx_dust_exposure = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat; + if holder_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() { + log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw); + return None; + } + if counterparty_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() { + log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw); + return None; + } + if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 { self.holding_cell_update_fee = Some(feerate_per_kw); return None; @@ -3271,7 +3283,7 @@ impl Channel { return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned())); } Channel::::check_remote_fee(fee_estimator, msg.feerate_per_kw)?; - let feerate_over_dust_buffer = msg.feerate_per_kw > self.get_dust_buffer_feerate(); + let feerate_over_dust_buffer = msg.feerate_per_kw > self.get_dust_buffer_feerate(None); self.pending_update_fee = Some((msg.feerate_per_kw, FeeUpdateState::RemoteAnnounced)); self.update_time_counter += 1; @@ -3279,8 +3291,8 @@ impl Channel { // `get_dust_buffer_feerate` considers the `pending_update_fee` status), check that we // won't be pushed over our dust exposure limit by the feerate increase. if feerate_over_dust_buffer { - let inbound_stats = self.get_inbound_pending_htlc_stats(); - let outbound_stats = self.get_outbound_pending_htlc_stats(); + let inbound_stats = self.get_inbound_pending_htlc_stats(None); + let outbound_stats = self.get_outbound_pending_htlc_stats(None); let holder_tx_dust_exposure = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat; let counterparty_tx_dust_exposure = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat; if holder_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() { @@ -3981,7 +3993,7 @@ impl Channel { self.feerate_per_kw } - pub fn get_dust_buffer_feerate(&self) -> u32 { + pub fn get_dust_buffer_feerate(&self, outbound_feerate_update: Option) -> u32 { // When calculating our exposure to dust HTLCs, we assume that the channel feerate // may, at any point, increase by at least 10 sat/vB (i.e 2530 sat/kWU) or 25%, // whichever is higher. This ensures that we aren't suddenly exposed to significantly @@ -3993,6 +4005,9 @@ impl Channel { if let Some((feerate, _)) = self.pending_update_fee { feerate_per_kw = cmp::max(feerate_per_kw, feerate); } + if let Some(feerate) = outbound_feerate_update { + feerate_per_kw = cmp::max(feerate_per_kw, feerate); + } cmp::max(2530, feerate_per_kw * 1250 / 1000) } @@ -4655,8 +4670,8 @@ impl Channel { return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected from channel counterparty".to_owned())); } - let inbound_stats = self.get_inbound_pending_htlc_stats(); - let outbound_stats = self.get_outbound_pending_htlc_stats(); + let inbound_stats = self.get_inbound_pending_htlc_stats(None); + let outbound_stats = self.get_outbound_pending_htlc_stats(None); if outbound_stats.pending_htlcs + 1 > self.counterparty_max_accepted_htlcs as u32 { return Err(ChannelError::Ignore(format!("Cannot push more than their max accepted HTLCs ({})", self.counterparty_max_accepted_htlcs))); } @@ -4677,7 +4692,7 @@ impl Channel { } } - let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; + let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis; if amount_msat / 1000 < exposure_dust_limit_success_sats { let on_counterparty_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + amount_msat; if on_counterparty_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() { @@ -4686,7 +4701,7 @@ impl Channel { } } - let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; + let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis; if amount_msat / 1000 < exposure_dust_limit_timeout_sats { let on_holder_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + amount_msat; if on_holder_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() { -- 2.39.5