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carrot_impl: input_count_for_max_usable_money fix

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This commit is contained in:
jeffro256
2025-04-07 14:48:44 -05:00
committed by akildemir
parent 316aacbc62
commit ad1eb77d50
1 changed files with 16 additions and 13 deletions
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29
src/carrot_impl/input_selection.cpp
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@@ -105,19 +105,19 @@ static void stable_sort_indices_by_block_index(const epee::span<const CarrotPreS
//-------------------------------------------------------------------------------------------------------------------
static std::pair<size_t, boost::multiprecision::int128_t> input_count_for_max_usable_money(
const epee::span<const CarrotPreSelectedInput> input_candidates,
const std::set<size_t> selectable_inputs,
const std::map<size_t, boost::multiprecision::int128_t> &required_money_by_input_count)
const std::set<size_t> &selectable_inputs,
const std::map<size_t, rct::xmr_amount> &fee_by_input_count)
{
// Returns (N, X) where the X is the sum of the amounts of the greatest N <= CARROT_MAX_TX_INPUTS
// inputs from selectable_inputs, maximizing X - R(N). R(N) is the required money for this
// transaction, including fee, for given input count N. This should correctly handle "almost-dust":
// inputs which are less than the fee, but greater than or equal to the difference of the fee
// compared to excluding that input. If this function returns N == 0, then there aren't enough
// usable funds, i.e. no N exists such that X - R(N) > 0.
// inputs from selectable_inputs, maximizing X - F(N). F(N) is the fee for this transaction,
// given input count N. This should correctly handle "almost-dust": inputs which are less than
// the fee, but greater than or equal to the difference of the fee compared to excluding that
// input. If this function returns N == 0, then there aren't enough usable funds, i.e. no N
// exists such that X - F(N) > 0.
size_t num_ins = 0;
boost::multiprecision::int128_t cumulative_input_sum = 0;
boost::multiprecision::int128_t last_required_money = 0;
rct::xmr_amount last_fee = 0;
std::vector<size_t> selectable_inputs_vec(selectable_inputs.cbegin(), selectable_inputs.cend());
stable_sort_indices_by_amount(input_candidates, selectable_inputs_vec);
@@ -125,13 +125,14 @@ static std::pair<size_t, boost::multiprecision::int128_t> input_count_for_max_us
// for selectable indices in descending amount...
for (auto it = selectable_inputs_vec.crbegin(); it != selectable_inputs_vec.crend(); ++it)
{
++num_ins;
if (num_ins > CARROT_MAX_TX_INPUTS)
if (num_ins == CARROT_MAX_TX_INPUTS)
break;
++num_ins;
const rct::xmr_amount amount = input_candidates[*it].core.amount;
if (amount < required_money_by_input_count.at(num_ins) - last_required_money)
if (amount < fee_by_input_count.at(num_ins) - last_fee)
{
// then this input doesn't pay for itself, rollback previous state and break
// since all next inputs will have same amount or less
@@ -140,6 +141,7 @@ static std::pair<size_t, boost::multiprecision::int128_t> input_count_for_max_us
}
cumulative_input_sum += amount;
last_fee = fee_by_input_count.at(num_ins);
}
return {num_ins, cumulative_input_sum};
@@ -256,8 +258,9 @@ select_inputs_func_t make_single_transfer_input_selector(
// Return early if not enough money in this selectable set...
const auto max_usable_money = input_count_for_max_usable_money(input_candidates,
selectable_indices,
required_money_by_input_count);
const bool enough_money = max_usable_money.first > 0;
fee_by_input_count);
const bool enough_money = max_usable_money.first > 0
&& max_usable_money.second >= required_money_by_input_count.at(max_usable_money.first);
if (!enough_money)
return;