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// Copyright (c) 2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <policy/feerate.h>
#include <policy/policy.h>
#include <primitives/transaction.h>
#include <test/fuzz/FuzzedDataProvider.h>
#include <test/fuzz/fuzz.h>
#include <test/fuzz/util.h>
#include <test/util/setup_common.h>
#include <wallet/coinselection.h>
#include <vector>
namespace wallet {
static void AddCoin(const CAmount& value, int n_input, int n_input_bytes, int locktime, std::vector<COutput>& coins, CFeeRate fee_rate)
{
CMutableTransaction tx;
tx.vout.resize(n_input + 1);
tx.vout[n_input].nValue = value;
tx.nLockTime = locktime; // all transactions get different hashes
coins.emplace_back(COutPoint(tx.GetHash(), n_input), tx.vout.at(n_input), /*depth=*/0, n_input_bytes, /*spendable=*/true, /*solvable=*/true, /*safe=*/true, /*time=*/0, /*from_me=*/true, fee_rate);
}
// Randomly distribute coins to instances of OutputGroup
static void GroupCoins(FuzzedDataProvider& fuzzed_data_provider, const std::vector<COutput>& coins, const CoinSelectionParams& coin_params, bool positive_only, std::vector<OutputGroup>& output_groups)
{
auto output_group = OutputGroup(coin_params);
bool valid_outputgroup{false};
for (auto& coin : coins) {
if (!positive_only || (positive_only && coin.GetEffectiveValue() > 0)) {
output_group.Insert(std::make_shared<COutput>(coin), /*ancestors=*/0, /*descendants=*/0);
}
// If positive_only was specified, nothing was inserted, leading to an empty output group
// that would be invalid for the BnB algorithm
valid_outputgroup = !positive_only || output_group.GetSelectionAmount() > 0;
if (valid_outputgroup && fuzzed_data_provider.ConsumeBool()) {
output_groups.push_back(output_group);
output_group = OutputGroup(coin_params);
valid_outputgroup = false;
}
}
if (valid_outputgroup) output_groups.push_back(output_group);
}
static CAmount CreateCoins(FuzzedDataProvider& fuzzed_data_provider, std::vector<COutput>& utxo_pool, CoinSelectionParams& coin_params, int& next_locktime)
{
CAmount total_balance{0};
LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000)
{
const int n_input{fuzzed_data_provider.ConsumeIntegralInRange<int>(0, 10)};
const int n_input_bytes{fuzzed_data_provider.ConsumeIntegralInRange<int>(41, 10000)};
const CAmount amount{fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(1, MAX_MONEY)};
if (total_balance + amount >= MAX_MONEY) {
break;
}
AddCoin(amount, n_input, n_input_bytes, ++next_locktime, utxo_pool, coin_params.m_effective_feerate);
total_balance += amount;
}
return total_balance;
}
static SelectionResult ManualSelection(std::vector<COutput>& utxos, const CAmount& total_amount, const bool& subtract_fee_outputs)
{
SelectionResult result(total_amount, SelectionAlgorithm::MANUAL);
std::set<std::shared_ptr<COutput>> utxo_pool;
for (const auto& utxo : utxos) {
utxo_pool.insert(std::make_shared<COutput>(utxo));
}
result.AddInputs(utxo_pool, subtract_fee_outputs);
return result;
}
// Returns true if the result contains an error and the message is not empty
static bool HasErrorMsg(const util::Result<SelectionResult>& res) { return !util::ErrorString(res).empty(); }
FUZZ_TARGET(coinselection)
{
FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
std::vector<COutput> utxo_pool;
const CFeeRate long_term_fee_rate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
const CFeeRate effective_fee_rate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
// Discard feerate must be at least dust relay feerate
const CFeeRate discard_fee_rate{fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(DUST_RELAY_TX_FEE, COIN)};
const CAmount target{fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(1, MAX_MONEY)};
const bool subtract_fee_outputs{fuzzed_data_provider.ConsumeBool()};
FastRandomContext fast_random_context{ConsumeUInt256(fuzzed_data_provider)};
CoinSelectionParams coin_params{fast_random_context};
coin_params.m_subtract_fee_outputs = subtract_fee_outputs;
coin_params.m_long_term_feerate = long_term_fee_rate;
coin_params.m_effective_feerate = effective_fee_rate;
coin_params.change_output_size = fuzzed_data_provider.ConsumeIntegralInRange(1, MAX_SCRIPT_SIZE);
coin_params.m_change_fee = effective_fee_rate.GetFee(coin_params.change_output_size);
coin_params.m_discard_feerate = discard_fee_rate;
coin_params.change_spend_size = fuzzed_data_provider.ConsumeIntegralInRange<int>(41, 1000);
const auto change_spend_fee{coin_params.m_discard_feerate.GetFee(coin_params.change_spend_size)};
coin_params.m_cost_of_change = coin_params.m_change_fee + change_spend_fee;
CScript change_out_script = CScript() << std::vector<unsigned char>(coin_params.change_output_size, OP_TRUE);
const auto dust{GetDustThreshold(CTxOut{/*nValueIn=*/0, change_out_script}, coin_params.m_discard_feerate)};
coin_params.min_viable_change = std::max(change_spend_fee + 1, dust);
int next_locktime{0};
CAmount total_balance{CreateCoins(fuzzed_data_provider, utxo_pool, coin_params, next_locktime)};
std::vector<OutputGroup> group_pos;
GroupCoins(fuzzed_data_provider, utxo_pool, coin_params, /*positive_only=*/true, group_pos);
std::vector<OutputGroup> group_all;
GroupCoins(fuzzed_data_provider, utxo_pool, coin_params, /*positive_only=*/false, group_all);
for (const OutputGroup& group : group_all) {
const CoinEligibilityFilter filter(fuzzed_data_provider.ConsumeIntegral<int>(), fuzzed_data_provider.ConsumeIntegral<int>(), fuzzed_data_provider.ConsumeIntegral<uint64_t>());
(void)group.EligibleForSpending(filter);
}
// Run coinselection algorithms
auto result_bnb = coin_params.m_subtract_fee_outputs ? util::Error{Untranslated("BnB disabled when SFFO is enabled")} :
SelectCoinsBnB(group_pos, target, coin_params.m_cost_of_change, MAX_STANDARD_TX_WEIGHT);
if (result_bnb) {
assert(result_bnb->GetChange(coin_params.min_viable_change, coin_params.m_change_fee) == 0);
assert(result_bnb->GetSelectedValue() >= target);
(void)result_bnb->GetShuffledInputVector();
(void)result_bnb->GetInputSet();
}
auto result_srd = SelectCoinsSRD(group_pos, target, coin_params.m_change_fee, fast_random_context, MAX_STANDARD_TX_WEIGHT);
if (result_srd) {
assert(result_srd->GetSelectedValue() >= target);
assert(result_srd->GetChange(CHANGE_LOWER, coin_params.m_change_fee) > 0); // Demonstrate that SRD creates change of at least CHANGE_LOWER
result_srd->ComputeAndSetWaste(coin_params.min_viable_change, coin_params.m_cost_of_change, coin_params.m_change_fee);
(void)result_srd->GetShuffledInputVector();
(void)result_srd->GetInputSet();
}
CAmount change_target{GenerateChangeTarget(target, coin_params.m_change_fee, fast_random_context)};
auto result_knapsack = KnapsackSolver(group_all, target, change_target, fast_random_context, MAX_STANDARD_TX_WEIGHT);
if (result_knapsack) {
assert(result_knapsack->GetSelectedValue() >= target);
result_knapsack->ComputeAndSetWaste(coin_params.min_viable_change, coin_params.m_cost_of_change, coin_params.m_change_fee);
(void)result_knapsack->GetShuffledInputVector();
(void)result_knapsack->GetInputSet();
}
// If the total balance is sufficient for the target and we are not using
// effective values, Knapsack should always find a solution (unless the selection exceeded the max tx weight).
if (total_balance >= target && subtract_fee_outputs && !HasErrorMsg(result_knapsack)) {
assert(result_knapsack);
}
std::vector<COutput> utxos;
std::vector<util::Result<SelectionResult>> results{result_srd, result_knapsack, result_bnb};
CAmount new_total_balance{CreateCoins(fuzzed_data_provider, utxos, coin_params, next_locktime)};
if (new_total_balance > 0) {
std::set<std::shared_ptr<COutput>> new_utxo_pool;
for (const auto& utxo : utxos) {
new_utxo_pool.insert(std::make_shared<COutput>(utxo));
}
for (auto& result : results) {
if (!result) continue;
const auto weight{result->GetWeight()};
result->AddInputs(new_utxo_pool, subtract_fee_outputs);
assert(result->GetWeight() > weight);
}
}
std::vector<COutput> manual_inputs;
CAmount manual_balance{CreateCoins(fuzzed_data_provider, manual_inputs, coin_params, next_locktime)};
if (manual_balance == 0) return;
auto manual_selection{ManualSelection(manual_inputs, manual_balance, coin_params.m_subtract_fee_outputs)};
for (auto& result : results) {
if (!result) continue;
const CAmount old_target{result->GetTarget()};
const std::set<std::shared_ptr<COutput>> input_set{result->GetInputSet()};
const int old_weight{result->GetWeight()};
result->Merge(manual_selection);
assert(result->GetInputSet().size() == input_set.size() + manual_inputs.size());
assert(result->GetTarget() == old_target + manual_selection.GetTarget());
assert(result->GetWeight() == old_weight + manual_selection.GetWeight());
}
}
} // namespace wallet
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