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Use saturating math for reserve and LSPS amounts #1185

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Merged
tnull merged 2 commits into from
Oct 22, 2026
Merged

Use saturating math for reserve and LSPS amounts #1185

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eb2a9d8
Saturate anchor reserve arithmetic
benthecarman Oct 20, 2026
3ba6ec0
Saturate LSPS channel size arithmetic
benthecarman Oct 20, 2026
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11 changes: 6 additions & 5 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1402,7 +1402,8 @@ impl Node {
total_anchor_channels_reserve_sats(&self.channel_manager, &self.config);
let new_channel_reserve =
self.new_channel_anchor_reserve_sats(&peer_info.node_id)?;
let total_anchor_reserve_sats = cur_anchor_reserve_sats + new_channel_reserve;
let total_anchor_reserve_sats =
cur_anchor_reserve_sats.saturating_add(new_channel_reserve);

let fee_rate = fee_rate.unwrap_or_else(|| {
self.fee_estimator.estimate_fee_rate(ConfirmationTarget::ChannelFunding)
Expand Down Expand Up @@ -1529,7 +1530,7 @@ impl Node {

if for_new_channel {
let required_funds_sats =
amount_sats + self.new_channel_anchor_reserve_sats(peer_node_id)?;
amount_sats.saturating_add(self.new_channel_anchor_reserve_sats(peer_node_id)?);

if spendable_amount_sats < required_funds_sats {
log_error!(self.logger,
Expand Down Expand Up @@ -2717,7 +2718,7 @@ impl_writeable_tlv_based!(NodeMetrics, {
pub(crate) fn total_anchor_channels_reserve_sats(
channel_manager: &ChannelManager, config: &Config,
) -> u64 {
channel_manager
let num_reserved_channels = channel_manager
.list_channels()
.into_iter()
.filter(|c| {
Expand All @@ -2729,8 +2730,8 @@ pub(crate) fn total_anchor_channels_reserve_sats(
.map_or(true, |s| s != ChannelShutdownState::ShutdownComplete)
&& c.channel_type.as_ref().map_or(true, requires_anchor_channel_type)
})
.count() as u64
* config.anchor_channels_config.per_channel_reserve_sats
.count() as u64;
num_reserved_channels.saturating_mul(config.anchor_channels_config.per_channel_reserve_sats)
}

pub(crate) fn new_channel_anchor_reserve_sats(
Expand Down
2 changes: 1 addition & 1 deletion src/liquidity/client/lsps1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -98,7 +98,7 @@ where
})?;

let lsp_limits = self.lsps1_request_opening_params(node_id).await?.supported_options;
let channel_size_sat = lsp_balance_sat + client_balance_sat;
let channel_size_sat = lsp_balance_sat.saturating_add(client_balance_sat);

if channel_size_sat < lsp_limits.min_channel_balance_sat
|| channel_size_sat > lsp_limits.max_channel_balance_sat
Expand Down
10 changes: 6 additions & 4 deletions src/liquidity/service/lsps2.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -445,10 +445,11 @@ where
};

// Fail if we have insufficient onchain funds available.
let over_provisioning_msat = (amt_to_forward_msat
* service_config.channel_over_provisioning_ppm as u64)
let over_provisioning_msat = amt_to_forward_msat
.saturating_mul(service_config.channel_over_provisioning_ppm as u64)
/ 1_000_000;
let channel_amount_sats = (amt_to_forward_msat + over_provisioning_msat) / 1000;
let channel_amount_sats =
amt_to_forward_msat.saturating_add(over_provisioning_msat) / 1000;
let cur_anchor_reserve_sats =
total_anchor_channels_reserve_sats(&self.channel_manager, &self.config);
let spendable_amount_sats =
Expand All @@ -460,7 +461,8 @@ where
&their_network_key,
anchor_channel,
);
let required_funds_sats = channel_amount_sats + additional_reserve_required;
let required_funds_sats =
channel_amount_sats.saturating_add(additional_reserve_required);
if spendable_amount_sats < required_funds_sats {
log_error!(self.logger,
"Unable to create channel due to insufficient funds. Available: {}sats, Required: {}sats",
Expand Down
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