From: jbesraa Date: Tue, 26 Mar 2024 17:23:37 +0000 (+0200) Subject: Fix `cmp::max` execution in `ChannelContext::get_dust_buffer_feerate` X-Git-Tag: v0.0.123-beta~12^2 X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=c01745eec7414a340404398255dcd54580380348;p=rust-lightning Fix `cmp::max` execution in `ChannelContext::get_dust_buffer_feerate` The current `cmp::max` doesnt align with the function comment, ie its comparing 2530 and `feerate_plus_quarter` instead of `feerate_per_kw + 2530` and `feerate_plus_quarter` which is fixed in this commit --- diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index 2698abee2..58d35a1a9 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -2730,7 +2730,7 @@ impl ChannelContext where SP::Target: SignerProvider { feerate_per_kw = cmp::max(feerate_per_kw, feerate); } let feerate_plus_quarter = feerate_per_kw.checked_mul(1250).map(|v| v / 1000); - cmp::max(2530, feerate_plus_quarter.unwrap_or(u32::max_value())) + cmp::max(feerate_per_kw + 2530, feerate_plus_quarter.unwrap_or(u32::max_value())) } /// Get forwarding information for the counterparty. diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index 5ea3e6372..8dd3f1fc9 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -9950,7 +9950,10 @@ fn do_test_max_dust_htlc_exposure(dust_outbound_balance: bool, exposure_breach_e let dust_outbound_htlc_on_holder_tx_msat: u64 = (dust_buffer_feerate * htlc_timeout_tx_weight(&channel_type_features) / 1000 + open_channel.common_fields.dust_limit_satoshis - 1) * 1000; let dust_outbound_htlc_on_holder_tx: u64 = max_dust_htlc_exposure_msat / dust_outbound_htlc_on_holder_tx_msat; - let dust_inbound_htlc_on_holder_tx_msat: u64 = (dust_buffer_feerate * htlc_success_tx_weight(&channel_type_features) / 1000 + open_channel.common_fields.dust_limit_satoshis - 1) * 1000; + // Substract 3 sats for multiplier and 2 sats for fixed limit to make sure we are 50% below the dust limit. + // This is to make sure we fully use the dust limit. If we don't, we could end up with `dust_ibd_htlc_on_holder_tx` being 1 + // while `max_dust_htlc_exposure_msat` is not equal to `dust_outbound_htlc_on_holder_tx_msat`. + let dust_inbound_htlc_on_holder_tx_msat: u64 = (dust_buffer_feerate * htlc_success_tx_weight(&channel_type_features) / 1000 + open_channel.common_fields.dust_limit_satoshis - if multiplier_dust_limit { 3 } else { 2 }) * 1000; let dust_inbound_htlc_on_holder_tx: u64 = max_dust_htlc_exposure_msat / dust_inbound_htlc_on_holder_tx_msat; let dust_htlc_on_counterparty_tx: u64 = 4;