From: Wilmer Paulino Date: Thu, 19 Oct 2023 16:25:23 +0000 (-0700) Subject: Consider anchor outputs value in get_available_balances X-Git-Tag: v0.0.118~4^2~3 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=d7672d4ebe59db94d145354f71962040891af013;p=rust-lightning Consider anchor outputs value in get_available_balances This could lead us to sending/forwarding HTLCs that would put us below our reserve, forcing our counterparty to close the channel on us due to an invalid update. --- diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index 6a468f2d6..8c835ed06 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -724,7 +724,7 @@ pub(super) struct ChannelContext where SP::Target: SignerProvider { cur_holder_commitment_transaction_number: u64, cur_counterparty_commitment_transaction_number: u64, - value_to_self_msat: u64, // Excluding all pending_htlcs, excluding fees + value_to_self_msat: u64, // Excluding all pending_htlcs, fees, and anchor outputs pending_inbound_htlcs: Vec, pending_outbound_htlcs: Vec, holding_cell_htlc_updates: Vec, @@ -1673,6 +1673,11 @@ impl ChannelContext where SP::Target: SignerProvider { let mut available_capacity_msat = outbound_capacity_msat; + let anchor_outputs_value_msat = if context.get_channel_type().supports_anchors_zero_fee_htlc_tx() { + ANCHOR_OUTPUT_VALUE_SATOSHI * 2 * 1000 + } else { + 0 + }; if context.is_outbound() { // We should mind channel commit tx fee when computing how much of the available capacity // can be used in the next htlc. Mirrors the logic in send_htlc. @@ -1694,7 +1699,8 @@ impl ChannelContext where SP::Target: SignerProvider { // 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, // match the value to right-below-dust. - let mut capacity_minus_commitment_fee_msat: i64 = (available_capacity_msat as i64) - (max_reserved_commit_tx_fee_msat as i64); + let mut capacity_minus_commitment_fee_msat: i64 = available_capacity_msat as i64 - + max_reserved_commit_tx_fee_msat as i64 - anchor_outputs_value_msat as i64; if capacity_minus_commitment_fee_msat < (real_dust_limit_timeout_sat as i64) * 1000 { let one_htlc_difference_msat = max_reserved_commit_tx_fee_msat - min_reserved_commit_tx_fee_msat; debug_assert!(one_htlc_difference_msat != 0); @@ -1719,7 +1725,7 @@ impl ChannelContext where SP::Target: SignerProvider { let remote_balance_msat = (context.channel_value_satoshis * 1000 - context.value_to_self_msat) .saturating_sub(inbound_stats.pending_htlcs_value_msat); - if remote_balance_msat < max_reserved_commit_tx_fee_msat + holder_selected_chan_reserve_msat { + if remote_balance_msat < max_reserved_commit_tx_fee_msat + holder_selected_chan_reserve_msat + anchor_outputs_value_msat { // If another HTLC's fee would reduce the remote's balance below the reserve limit // we've selected for them, we can only send dust HTLCs. available_capacity_msat = cmp::min(available_capacity_msat, real_dust_limit_success_sat * 1000 - 1);