Merge pull request #2674 from wpaulino/consider-anchor-outputs-value-balances
[rust-lightning] / lightning / src / ln / channel.rs
index 4552e6176ad21b16b094df3e2821f255ab9de820..f3632b41b471098392bf357e3a9e7220995588ce 100644 (file)
@@ -1692,9 +1692,13 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                        }
 
                        let htlc_above_dust = HTLCCandidate::new(real_dust_limit_timeout_sat * 1000, HTLCInitiator::LocalOffered);
-                       let max_reserved_commit_tx_fee_msat = FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE * context.next_local_commit_tx_fee_msat(htlc_above_dust, Some(()));
+                       let mut max_reserved_commit_tx_fee_msat = context.next_local_commit_tx_fee_msat(htlc_above_dust, Some(()));
                        let htlc_dust = HTLCCandidate::new(real_dust_limit_timeout_sat * 1000 - 1, HTLCInitiator::LocalOffered);
-                       let min_reserved_commit_tx_fee_msat = FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE * context.next_local_commit_tx_fee_msat(htlc_dust, Some(()));
+                       let mut min_reserved_commit_tx_fee_msat = context.next_local_commit_tx_fee_msat(htlc_dust, Some(()));
+                       if !context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
+                               max_reserved_commit_tx_fee_msat *= FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
+                               min_reserved_commit_tx_fee_msat *= FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
+                       }
 
                        // We will first subtract the fee as if we were above-dust. Then, if the resulting
                        // value ends up being below dust, we have this fee available again. In that case,
@@ -2856,16 +2860,15 @@ impl<SP: Deref> Channel<SP> where
                        0
                };
                if !self.context.is_outbound() {
-                       // `2 *` and `Some(())` is for the fee spike buffer we keep for the remote. This deviates from
-                       // the spec because in the spec, the fee spike buffer requirement doesn't exist on the
-                       // receiver's side, only on the sender's.
-                       // Note that when we eventually remove support for fee updates and switch to anchor output
-                       // fees, we will drop the `2 *`, since we no longer be as sensitive to fee spikes. But, keep
-                       // the extra htlc when calculating the next remote commitment transaction fee as we should
-                       // still be able to afford adding this HTLC plus one more future HTLC, regardless of being
-                       // sensitive to fee spikes.
+                       // `Some(())` is for the fee spike buffer we keep for the remote. This deviates from
+                       // the spec because the fee spike buffer requirement doesn't exist on the receiver's
+                       // side, only on the sender's. Note that with anchor outputs we are no longer as
+                       // sensitive to fee spikes, so we need to account for them.
                        let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
-                       let remote_fee_cost_incl_stuck_buffer_msat = 2 * self.context.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
+                       let mut remote_fee_cost_incl_stuck_buffer_msat = self.context.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
+                       if !self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
+                               remote_fee_cost_incl_stuck_buffer_msat *= FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
+                       }
                        if pending_remote_value_msat.saturating_sub(msg.amount_msat).saturating_sub(self.context.holder_selected_channel_reserve_satoshis * 1000).saturating_sub(anchor_outputs_value_msat) < remote_fee_cost_incl_stuck_buffer_msat {
                                // Note that if the pending_forward_status is not updated here, then it's because we're already failing
                                // the HTLC, i.e. its status is already set to failing.
@@ -5739,16 +5742,16 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                let channel_type = Self::get_initial_channel_type(&config, their_features);
                debug_assert!(channel_type.is_subset(&channelmanager::provided_channel_type_features(&config)));
 
-               let commitment_conf_target = if channel_type.supports_anchors_zero_fee_htlc_tx() {
-                       ConfirmationTarget::AnchorChannelFee
+               let (commitment_conf_target, anchor_outputs_value_msat)  = if channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       (ConfirmationTarget::AnchorChannelFee, ANCHOR_OUTPUT_VALUE_SATOSHI * 2 * 1000)
                } else {
-                       ConfirmationTarget::NonAnchorChannelFee
+                       (ConfirmationTarget::NonAnchorChannelFee, 0)
                };
                let commitment_feerate = fee_estimator.bounded_sat_per_1000_weight(commitment_conf_target);
 
                let value_to_self_msat = channel_value_satoshis * 1000 - push_msat;
                let commitment_tx_fee = commit_tx_fee_msat(commitment_feerate, MIN_AFFORDABLE_HTLC_COUNT, &channel_type);
-               if value_to_self_msat < commitment_tx_fee {
+               if value_to_self_msat.saturating_sub(anchor_outputs_value_msat) < commitment_tx_fee {
                        return Err(APIError::APIMisuseError{ err: format!("Funding amount ({}) can't even pay fee for initial commitment transaction fee of {}.", value_to_self_msat / 1000, commitment_tx_fee / 1000) });
                }
 
@@ -6365,13 +6368,18 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
                // check if the funder's amount for the initial commitment tx is sufficient
                // for full fee payment plus a few HTLCs to ensure the channel will be useful.
+               let anchor_outputs_value = if channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2
+               } else {
+                       0
+               };
                let funders_amount_msat = msg.funding_satoshis * 1000 - msg.push_msat;
                let commitment_tx_fee = commit_tx_fee_msat(msg.feerate_per_kw, MIN_AFFORDABLE_HTLC_COUNT, &channel_type) / 1000;
-               if funders_amount_msat / 1000 < commitment_tx_fee {
-                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", funders_amount_msat / 1000, commitment_tx_fee)));
+               if (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value) < commitment_tx_fee {
+                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value), commitment_tx_fee)));
                }
 
-               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee;
+               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee - anchor_outputs_value;
                // While it's reasonable for us to not meet the channel reserve initially (if they don't
                // want to push much to us), our counterparty should always have more than our reserve.
                if to_remote_satoshis < holder_selected_channel_reserve_satoshis {