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bitcoin-bitcoin-core/src/wallet/spend.cpp
Andrew Chow ba47a4ba97
Merge bitcoin/bitcoin#26668: wallet: if only have one output type, don't perform "mixed" coin selection 
89c1491d35 wallet: if only have one output type, don't perform "mixed" coin selection (furszy)

Pull request description:

  For wallets that only have one output type, we are currently performing the same
  selection process over the same coins twice.

  The "mixed coin selection" doesn't add any value to the result
  (there is nothing to mix if the available coins struct has only one type).

ACKs for top commit:
  achow101:
    ACK 89c1491d35
  john-moffett:
    ACK 89c1491d35
  kristapsk:
    cr utACK 89c1491d35

Tree-SHA512: 672eaeed3ba911d13fa61a46f719c8fe1ebe4d2dc7d723040e71937c693659411bc99cdbd9f0014e836b70eebeff1b8ca861f4d81d39e6f79f437364a526edbe
2022-12-14 16:16:03 -05:00

1185 lines
56 KiB
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// Copyright (c) 2021 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 <algorithm>
#include <consensus/amount.h>
#include <consensus/validation.h>
#include <interfaces/chain.h>
#include <numeric>
#include <policy/policy.h>
#include <primitives/transaction.h>
#include <script/signingprovider.h>
#include <util/check.h>
#include <util/fees.h>
#include <util/moneystr.h>
#include <util/rbf.h>
#include <util/trace.h>
#include <util/translation.h>
#include <wallet/coincontrol.h>
#include <wallet/fees.h>
#include <wallet/receive.h>
#include <wallet/spend.h>
#include <wallet/transaction.h>
#include <wallet/wallet.h>
#include <cmath>
using interfaces::FoundBlock;
namespace wallet {
static constexpr size_t OUTPUT_GROUP_MAX_ENTRIES{100};
int CalculateMaximumSignedInputSize(const CTxOut& txout, const COutPoint outpoint, const SigningProvider* provider, const CCoinControl* coin_control)
{
CMutableTransaction txn;
txn.vin.push_back(CTxIn(outpoint));
if (!provider || !DummySignInput(*provider, txn.vin[0], txout, coin_control)) {
return -1;
}
return GetVirtualTransactionInputSize(txn.vin[0]);
}
int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* wallet, const CCoinControl* coin_control)
{
const std::unique_ptr<SigningProvider> provider = wallet->GetSolvingProvider(txout.scriptPubKey);
return CalculateMaximumSignedInputSize(txout, COutPoint(), provider.get(), coin_control);
}
// txouts needs to be in the order of tx.vin
TxSize CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet, const std::vector<CTxOut>& txouts, const CCoinControl* coin_control)
{
CMutableTransaction txNew(tx);
if (!wallet->DummySignTx(txNew, txouts, coin_control)) {
return TxSize{-1, -1};
}
CTransaction ctx(txNew);
int64_t vsize = GetVirtualTransactionSize(ctx);
int64_t weight = GetTransactionWeight(ctx);
return TxSize{vsize, weight};
}
TxSize CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet, const CCoinControl* coin_control)
{
std::vector<CTxOut> txouts;
// Look up the inputs. The inputs are either in the wallet, or in coin_control.
for (const CTxIn& input : tx.vin) {
const auto mi = wallet->mapWallet.find(input.prevout.hash);
// Can not estimate size without knowing the input details
if (mi != wallet->mapWallet.end()) {
assert(input.prevout.n < mi->second.tx->vout.size());
txouts.emplace_back(mi->second.tx->vout.at(input.prevout.n));
} else if (coin_control) {
CTxOut txout;
if (!coin_control->GetExternalOutput(input.prevout, txout)) {
return TxSize{-1, -1};
}
txouts.emplace_back(txout);
} else {
return TxSize{-1, -1};
}
}
return CalculateMaximumSignedTxSize(tx, wallet, txouts, coin_control);
}
size_t CoinsResult::Size() const
{
size_t size{0};
for (const auto& it : coins) {
size += it.second.size();
}
return size;
}
std::vector<COutput> CoinsResult::All() const
{
std::vector<COutput> all;
all.reserve(coins.size());
for (const auto& it : coins) {
all.insert(all.end(), it.second.begin(), it.second.end());
}
return all;
}
void CoinsResult::Clear() {
coins.clear();
}
void CoinsResult::Erase(const std::unordered_set<COutPoint, SaltedOutpointHasher>& coins_to_remove)
{
for (auto& [type, vec] : coins) {
auto remove_it = std::remove_if(vec.begin(), vec.end(), [&](const COutput& coin) {
// remove it if it's on the set
if (coins_to_remove.count(coin.outpoint) == 0) return false;
// update cached amounts
total_amount -= coin.txout.nValue;
if (coin.HasEffectiveValue()) total_effective_amount = *total_effective_amount - coin.GetEffectiveValue();
return true;
});
vec.erase(remove_it, vec.end());
}
}
void CoinsResult::Shuffle(FastRandomContext& rng_fast)
{
for (auto& it : coins) {
::Shuffle(it.second.begin(), it.second.end(), rng_fast);
}
}
void CoinsResult::Add(OutputType type, const COutput& out)
{
coins[type].emplace_back(out);
total_amount += out.txout.nValue;
if (out.HasEffectiveValue()) {
total_effective_amount = total_effective_amount.has_value() ?
*total_effective_amount + out.GetEffectiveValue() : out.GetEffectiveValue();
}
}
static OutputType GetOutputType(TxoutType type, bool is_from_p2sh)
{
switch (type) {
case TxoutType::WITNESS_V1_TAPROOT:
return OutputType::BECH32M;
case TxoutType::WITNESS_V0_KEYHASH:
case TxoutType::WITNESS_V0_SCRIPTHASH:
if (is_from_p2sh) return OutputType::P2SH_SEGWIT;
else return OutputType::BECH32;
case TxoutType::SCRIPTHASH:
case TxoutType::PUBKEYHASH:
return OutputType::LEGACY;
default:
return OutputType::UNKNOWN;
}
}
// Fetch and validate the coin control selected inputs.
// Coins could be internal (from the wallet) or external.
util::Result<PreSelectedInputs> FetchSelectedInputs(const CWallet& wallet, const CCoinControl& coin_control,
const CoinSelectionParams& coin_selection_params) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
{
PreSelectedInputs result;
std::vector<COutPoint> vPresetInputs;
coin_control.ListSelected(vPresetInputs);
for (const COutPoint& outpoint : vPresetInputs) {
int input_bytes = -1;
CTxOut txout;
if (auto ptr_wtx = wallet.GetWalletTx(outpoint.hash)) {
// Clearly invalid input, fail
if (ptr_wtx->tx->vout.size() <= outpoint.n) {
return util::Error{strprintf(_("Invalid pre-selected input %s"), outpoint.ToString())};
}
txout = ptr_wtx->tx->vout.at(outpoint.n);
input_bytes = CalculateMaximumSignedInputSize(txout, &wallet, &coin_control);
} else {
// The input is external. We did not find the tx in mapWallet.
if (!coin_control.GetExternalOutput(outpoint, txout)) {
return util::Error{strprintf(_("Not found pre-selected input %s"), outpoint.ToString())};
}
}
if (input_bytes == -1) {
input_bytes = CalculateMaximumSignedInputSize(txout, outpoint, &coin_control.m_external_provider, &coin_control);
}
// If available, override calculated size with coin control specified size
if (coin_control.HasInputWeight(outpoint)) {
input_bytes = GetVirtualTransactionSize(coin_control.GetInputWeight(outpoint), 0, 0);
}
if (input_bytes == -1) {
return util::Error{strprintf(_("Not solvable pre-selected input %s"), outpoint.ToString())}; // Not solvable, can't estimate size for fee
}
/* Set some defaults for depth, spendable, solvable, safe, time, and from_me as these don't matter for preset inputs since no selection is being done. */
COutput output(outpoint, txout, /*depth=*/ 0, input_bytes, /*spendable=*/ true, /*solvable=*/ true, /*safe=*/ true, /*time=*/ 0, /*from_me=*/ false, coin_selection_params.m_effective_feerate);
result.Insert(output, coin_selection_params.m_subtract_fee_outputs);
}
return result;
}
CoinsResult AvailableCoins(const CWallet& wallet,
const CCoinControl* coinControl,
std::optional<CFeeRate> feerate,
const CoinFilterParams& params)
{
AssertLockHeld(wallet.cs_wallet);
CoinsResult result;
// Either the WALLET_FLAG_AVOID_REUSE flag is not set (in which case we always allow), or we default to avoiding, and only in the case where
// a coin control object is provided, and has the avoid address reuse flag set to false, do we allow already used addresses
bool allow_used_addresses = !wallet.IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE) || (coinControl && !coinControl->m_avoid_address_reuse);
const int min_depth = {coinControl ? coinControl->m_min_depth : DEFAULT_MIN_DEPTH};
const int max_depth = {coinControl ? coinControl->m_max_depth : DEFAULT_MAX_DEPTH};
const bool only_safe = {coinControl ? !coinControl->m_include_unsafe_inputs : true};
std::set<uint256> trusted_parents;
for (const auto& entry : wallet.mapWallet)
{
const uint256& wtxid = entry.first;
const CWalletTx& wtx = entry.second;
if (wallet.IsTxImmatureCoinBase(wtx) && !params.include_immature_coinbase)
continue;
int nDepth = wallet.GetTxDepthInMainChain(wtx);
if (nDepth < 0)
continue;
// We should not consider coins which aren't at least in our mempool
// It's possible for these to be conflicted via ancestors which we may never be able to detect
if (nDepth == 0 && !wtx.InMempool())
continue;
bool safeTx = CachedTxIsTrusted(wallet, wtx, trusted_parents);
// We should not consider coins from transactions that are replacing
// other transactions.
//
// Example: There is a transaction A which is replaced by bumpfee
// transaction B. In this case, we want to prevent creation of
// a transaction B' which spends an output of B.
//
// Reason: If transaction A were initially confirmed, transactions B
// and B' would no longer be valid, so the user would have to create
// a new transaction C to replace B'. However, in the case of a
// one-block reorg, transactions B' and C might BOTH be accepted,
// when the user only wanted one of them. Specifically, there could
// be a 1-block reorg away from the chain where transactions A and C
// were accepted to another chain where B, B', and C were all
// accepted.
if (nDepth == 0 && wtx.mapValue.count("replaces_txid")) {
safeTx = false;
}
// Similarly, we should not consider coins from transactions that
// have been replaced. In the example above, we would want to prevent
// creation of a transaction A' spending an output of A, because if
// transaction B were initially confirmed, conflicting with A and
// A', we wouldn't want to the user to create a transaction D
// intending to replace A', but potentially resulting in a scenario
// where A, A', and D could all be accepted (instead of just B and
// D, or just A and A' like the user would want).
if (nDepth == 0 && wtx.mapValue.count("replaced_by_txid")) {
safeTx = false;
}
if (only_safe && !safeTx) {
continue;
}
if (nDepth < min_depth || nDepth > max_depth) {
continue;
}
bool tx_from_me = CachedTxIsFromMe(wallet, wtx, ISMINE_ALL);
for (unsigned int i = 0; i < wtx.tx->vout.size(); i++) {
const CTxOut& output = wtx.tx->vout[i];
const COutPoint outpoint(wtxid, i);
if (output.nValue < params.min_amount || output.nValue > params.max_amount)
continue;
// Skip manually selected coins (the caller can fetch them directly)
if (coinControl && coinControl->HasSelected() && coinControl->IsSelected(outpoint))
continue;
if (wallet.IsLockedCoin(outpoint))
continue;
if (wallet.IsSpent(outpoint))
continue;
isminetype mine = wallet.IsMine(output);
if (mine == ISMINE_NO) {
continue;
}
if (!allow_used_addresses && wallet.IsSpentKey(output.scriptPubKey)) {
continue;
}
std::unique_ptr<SigningProvider> provider = wallet.GetSolvingProvider(output.scriptPubKey);
int input_bytes = CalculateMaximumSignedInputSize(output, COutPoint(), provider.get(), coinControl);
// Because CalculateMaximumSignedInputSize just uses ProduceSignature and makes a dummy signature,
// it is safe to assume that this input is solvable if input_bytes is greater -1.
bool solvable = input_bytes > -1;
bool spendable = ((mine & ISMINE_SPENDABLE) != ISMINE_NO) || (((mine & ISMINE_WATCH_ONLY) != ISMINE_NO) && (coinControl && coinControl->fAllowWatchOnly && solvable));
// Filter by spendable outputs only
if (!spendable && params.only_spendable) continue;
// Obtain script type
std::vector<std::vector<uint8_t>> script_solutions;
TxoutType type = Solver(output.scriptPubKey, script_solutions);
// If the output is P2SH and solvable, we want to know if it is
// a P2SH (legacy) or one of P2SH-P2WPKH, P2SH-P2WSH (P2SH-Segwit). We can determine
// this from the redeemScript. If the output is not solvable, it will be classified
// as a P2SH (legacy), since we have no way of knowing otherwise without the redeemScript
bool is_from_p2sh{false};
if (type == TxoutType::SCRIPTHASH && solvable) {
CScript script;
if (!provider->GetCScript(CScriptID(uint160(script_solutions[0])), script)) continue;
type = Solver(script, script_solutions);
is_from_p2sh = true;
}
result.Add(GetOutputType(type, is_from_p2sh),
COutput(outpoint, output, nDepth, input_bytes, spendable, solvable, safeTx, wtx.GetTxTime(), tx_from_me, feerate));
// Checks the sum amount of all UTXO's.
if (params.min_sum_amount != MAX_MONEY) {
if (result.GetTotalAmount() >= params.min_sum_amount) {
return result;
}
}
// Checks the maximum number of UTXO's.
if (params.max_count > 0 && result.Size() >= params.max_count) {
return result;
}
}
}
return result;
}
CoinsResult AvailableCoinsListUnspent(const CWallet& wallet, const CCoinControl* coinControl, CoinFilterParams params)
{
params.only_spendable = false;
return AvailableCoins(wallet, coinControl, /*feerate=*/ std::nullopt, params);
}
CAmount GetAvailableBalance(const CWallet& wallet, const CCoinControl* coinControl)
{
LOCK(wallet.cs_wallet);
return AvailableCoins(wallet, coinControl).GetTotalAmount();
}
const CTxOut& FindNonChangeParentOutput(const CWallet& wallet, const CTransaction& tx, int output)
{
AssertLockHeld(wallet.cs_wallet);
const CTransaction* ptx = &tx;
int n = output;
while (OutputIsChange(wallet, ptx->vout[n]) && ptx->vin.size() > 0) {
const COutPoint& prevout = ptx->vin[0].prevout;
auto it = wallet.mapWallet.find(prevout.hash);
if (it == wallet.mapWallet.end() || it->second.tx->vout.size() <= prevout.n ||
!wallet.IsMine(it->second.tx->vout[prevout.n])) {
break;
}
ptx = it->second.tx.get();
n = prevout.n;
}
return ptx->vout[n];
}
const CTxOut& FindNonChangeParentOutput(const CWallet& wallet, const COutPoint& outpoint)
{
AssertLockHeld(wallet.cs_wallet);
return FindNonChangeParentOutput(wallet, *wallet.GetWalletTx(outpoint.hash)->tx, outpoint.n);
}
std::map<CTxDestination, std::vector<COutput>> ListCoins(const CWallet& wallet)
{
AssertLockHeld(wallet.cs_wallet);
std::map<CTxDestination, std::vector<COutput>> result;
for (COutput& coin : AvailableCoinsListUnspent(wallet).All()) {
CTxDestination address;
if ((coin.spendable || (wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && coin.solvable)) &&
ExtractDestination(FindNonChangeParentOutput(wallet, coin.outpoint).scriptPubKey, address)) {
result[address].emplace_back(std::move(coin));
}
}
std::vector<COutPoint> lockedCoins;
wallet.ListLockedCoins(lockedCoins);
// Include watch-only for LegacyScriptPubKeyMan wallets without private keys
const bool include_watch_only = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
const isminetype is_mine_filter = include_watch_only ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
for (const COutPoint& output : lockedCoins) {
auto it = wallet.mapWallet.find(output.hash);
if (it != wallet.mapWallet.end()) {
const auto& wtx = it->second;
int depth = wallet.GetTxDepthInMainChain(wtx);
if (depth >= 0 && output.n < wtx.tx->vout.size() &&
wallet.IsMine(wtx.tx->vout[output.n]) == is_mine_filter
) {
CTxDestination address;
if (ExtractDestination(FindNonChangeParentOutput(wallet, *wtx.tx, output.n).scriptPubKey, address)) {
const auto out = wtx.tx->vout.at(output.n);
result[address].emplace_back(
COutPoint(wtx.GetHash(), output.n), out, depth, CalculateMaximumSignedInputSize(out, &wallet, /*coin_control=*/nullptr), /*spendable=*/ true, /*solvable=*/ true, /*safe=*/ false, wtx.GetTxTime(), CachedTxIsFromMe(wallet, wtx, ISMINE_ALL));
}
}
}
}
return result;
}
std::vector<OutputGroup> GroupOutputs(const CWallet& wallet, const std::vector<COutput>& outputs, const CoinSelectionParams& coin_sel_params, const CoinEligibilityFilter& filter, bool positive_only)
{
std::vector<OutputGroup> groups_out;
if (!coin_sel_params.m_avoid_partial_spends) {
// Allowing partial spends means no grouping. Each COutput gets its own OutputGroup.
for (const COutput& output : outputs) {
// Skip outputs we cannot spend
if (!output.spendable) continue;
size_t ancestors, descendants;
wallet.chain().getTransactionAncestry(output.outpoint.hash, ancestors, descendants);
// Make an OutputGroup containing just this output
OutputGroup group{coin_sel_params};
group.Insert(output, ancestors, descendants, positive_only);
// Check the OutputGroup's eligibility. Only add the eligible ones.
if (positive_only && group.GetSelectionAmount() <= 0) continue;
if (group.m_outputs.size() > 0 && group.EligibleForSpending(filter)) groups_out.push_back(group);
}
return groups_out;
}
// We want to combine COutputs that have the same scriptPubKey into single OutputGroups
// except when there are more than OUTPUT_GROUP_MAX_ENTRIES COutputs grouped in an OutputGroup.
// To do this, we maintain a map where the key is the scriptPubKey and the value is a vector of OutputGroups.
// For each COutput, we check if the scriptPubKey is in the map, and if it is, the COutput is added
// to the last OutputGroup in the vector for the scriptPubKey. When the last OutputGroup has
// OUTPUT_GROUP_MAX_ENTRIES COutputs, a new OutputGroup is added to the end of the vector.
std::map<CScript, std::vector<OutputGroup>> spk_to_groups_map;
for (const auto& output : outputs) {
// Skip outputs we cannot spend
if (!output.spendable) continue;
size_t ancestors, descendants;
wallet.chain().getTransactionAncestry(output.outpoint.hash, ancestors, descendants);
CScript spk = output.txout.scriptPubKey;
std::vector<OutputGroup>& groups = spk_to_groups_map[spk];
if (groups.size() == 0) {
// No OutputGroups for this scriptPubKey yet, add one
groups.emplace_back(coin_sel_params);
}
// Get the last OutputGroup in the vector so that we can add the COutput to it
// A pointer is used here so that group can be reassigned later if it is full.
OutputGroup* group = &groups.back();
// Check if this OutputGroup is full. We limit to OUTPUT_GROUP_MAX_ENTRIES when using -avoidpartialspends
// to avoid surprising users with very high fees.
if (group->m_outputs.size() >= OUTPUT_GROUP_MAX_ENTRIES) {
// The last output group is full, add a new group to the vector and use that group for the insertion
groups.emplace_back(coin_sel_params);
group = &groups.back();
}
// Add the output to group
group->Insert(output, ancestors, descendants, positive_only);
}
// Now we go through the entire map and pull out the OutputGroups
for (const auto& spk_and_groups_pair: spk_to_groups_map) {
const std::vector<OutputGroup>& groups_per_spk= spk_and_groups_pair.second;
// Go through the vector backwards. This allows for the first item we deal with being the partial group.
for (auto group_it = groups_per_spk.rbegin(); group_it != groups_per_spk.rend(); group_it++) {
const OutputGroup& group = *group_it;
// Don't include partial groups if there are full groups too and we don't want partial groups
if (group_it == groups_per_spk.rbegin() && groups_per_spk.size() > 1 && !filter.m_include_partial_groups) {
continue;
}
// Check the OutputGroup's eligibility. Only add the eligible ones.
if (positive_only && group.GetSelectionAmount() <= 0) continue;
if (group.m_outputs.size() > 0 && group.EligibleForSpending(filter)) groups_out.push_back(group);
}
}
return groups_out;
}
std::optional<SelectionResult> AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, const CoinsResult& available_coins,
const CoinSelectionParams& coin_selection_params, bool allow_mixed_output_types)
{
// Run coin selection on each OutputType and compute the Waste Metric
std::vector<SelectionResult> results;
for (const auto& it : available_coins.coins) {
if (auto result{ChooseSelectionResult(wallet, nTargetValue, eligibility_filter, it.second, coin_selection_params)}) {
results.push_back(*result);
}
}
// If we have at least one solution for funding the transaction without mixing, choose the minimum one according to waste metric
// and return the result
if (results.size() > 0) return *std::min_element(results.begin(), results.end());
// If we can't fund the transaction from any individual OutputType, run coin selection one last time
// over all available coins, which would allow mixing.
// If TypesCount() <= 1, there is nothing to mix.
if (allow_mixed_output_types && available_coins.TypesCount() > 1) {
if (auto result{ChooseSelectionResult(wallet, nTargetValue, eligibility_filter, available_coins.All(), coin_selection_params)}) {
return result;
}
}
// Either mixing is not allowed and we couldn't find a solution from any single OutputType, or mixing was allowed and we still couldn't
// find a solution using all available coins
return std::nullopt;
};
std::optional<SelectionResult> ChooseSelectionResult(const CWallet& wallet, const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, const std::vector<COutput>& available_coins, const CoinSelectionParams& coin_selection_params)
{
// Vector of results. We will choose the best one based on waste.
std::vector<SelectionResult> results;
std::vector<OutputGroup> positive_groups = GroupOutputs(wallet, available_coins, coin_selection_params, eligibility_filter, /*positive_only=*/true);
if (auto bnb_result{SelectCoinsBnB(positive_groups, nTargetValue, coin_selection_params.m_cost_of_change)}) {
results.push_back(*bnb_result);
}
// The knapsack solver has some legacy behavior where it will spend dust outputs. We retain this behavior, so don't filter for positive only here.
std::vector<OutputGroup> all_groups = GroupOutputs(wallet, available_coins, coin_selection_params, eligibility_filter, /*positive_only=*/false);
if (auto knapsack_result{KnapsackSolver(all_groups, nTargetValue, coin_selection_params.m_min_change_target, coin_selection_params.rng_fast)}) {
knapsack_result->ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
results.push_back(*knapsack_result);
}
if (auto srd_result{SelectCoinsSRD(positive_groups, nTargetValue, coin_selection_params.rng_fast)}) {
srd_result->ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
results.push_back(*srd_result);
}
if (results.empty()) {
// No solution found
return std::nullopt;
}
std::vector<SelectionResult> eligible_results;
std::copy_if(results.begin(), results.end(), std::back_inserter(eligible_results), [coin_selection_params](const SelectionResult& result) {
const auto initWeight{coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR};
return initWeight + result.GetWeight() <= static_cast<int>(MAX_STANDARD_TX_WEIGHT);
});
if (eligible_results.empty()) {
return std::nullopt;
}
// Choose the result with the least waste
// If the waste is the same, choose the one which spends more inputs.
auto& best_result = *std::min_element(eligible_results.begin(), eligible_results.end());
return best_result;
}
std::optional<SelectionResult> SelectCoins(const CWallet& wallet, CoinsResult& available_coins, const PreSelectedInputs& pre_set_inputs,
const CAmount& nTargetValue, const CCoinControl& coin_control,
const CoinSelectionParams& coin_selection_params)
{
// Deduct preset inputs amount from the search target
CAmount selection_target = nTargetValue - pre_set_inputs.total_amount;
// Return if automatic coin selection is disabled, and we don't cover the selection target
if (!coin_control.m_allow_other_inputs && selection_target > 0) return std::nullopt;
// Return if we can cover the target only with the preset inputs
if (selection_target <= 0) {
SelectionResult result(nTargetValue, SelectionAlgorithm::MANUAL);
result.AddInputs(pre_set_inputs.coins, coin_selection_params.m_subtract_fee_outputs);
result.ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
return result;
}
// Return early if we cannot cover the target with the wallet's UTXO.
// We use the total effective value if we are not subtracting fee from outputs and 'available_coins' contains the data.
CAmount available_coins_total_amount = coin_selection_params.m_subtract_fee_outputs ? available_coins.GetTotalAmount() :
(available_coins.GetEffectiveTotalAmount().has_value() ? *available_coins.GetEffectiveTotalAmount() : 0);
if (selection_target > available_coins_total_amount) {
return std::nullopt; // Insufficient funds
}
// Start wallet Coin Selection procedure
auto op_selection_result = AutomaticCoinSelection(wallet, available_coins, selection_target, coin_control, coin_selection_params);
if (!op_selection_result) return op_selection_result;
// If needed, add preset inputs to the automatic coin selection result
if (!pre_set_inputs.coins.empty()) {
SelectionResult preselected(pre_set_inputs.total_amount, SelectionAlgorithm::MANUAL);
preselected.AddInputs(pre_set_inputs.coins, coin_selection_params.m_subtract_fee_outputs);
op_selection_result->Merge(preselected);
op_selection_result->ComputeAndSetWaste(coin_selection_params.min_viable_change,
coin_selection_params.m_cost_of_change,
coin_selection_params.m_change_fee);
}
return op_selection_result;
}
std::optional<SelectionResult> AutomaticCoinSelection(const CWallet& wallet, CoinsResult& available_coins, const CAmount& value_to_select, const CCoinControl& coin_control, const CoinSelectionParams& coin_selection_params)
{
unsigned int limit_ancestor_count = 0;
unsigned int limit_descendant_count = 0;
wallet.chain().getPackageLimits(limit_ancestor_count, limit_descendant_count);
const size_t max_ancestors = (size_t)std::max<int64_t>(1, limit_ancestor_count);
const size_t max_descendants = (size_t)std::max<int64_t>(1, limit_descendant_count);
const bool fRejectLongChains = gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
// form groups from remaining coins; note that preset coins will not
// automatically have their associated (same address) coins included
if (coin_control.m_avoid_partial_spends && available_coins.Size() > OUTPUT_GROUP_MAX_ENTRIES) {
// Cases where we have 101+ outputs all pointing to the same destination may result in
// privacy leaks as they will potentially be deterministically sorted. We solve that by
// explicitly shuffling the outputs before processing
available_coins.Shuffle(coin_selection_params.rng_fast);
}
// Coin Selection attempts to select inputs from a pool of eligible UTXOs to fund the
// transaction at a target feerate. If an attempt fails, more attempts may be made using a more
// permissive CoinEligibilityFilter.
std::optional<SelectionResult> res = [&] {
// If possible, fund the transaction with confirmed UTXOs only. Prefer at least six
// confirmations on outputs received from other wallets and only spend confirmed change.
if (auto r1{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(1, 6, 0), available_coins, coin_selection_params, /*allow_mixed_output_types=*/false)}) return r1;
// Allow mixing only if no solution from any single output type can be found
if (auto r2{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(1, 1, 0), available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) return r2;
// Fall back to using zero confirmation change (but with as few ancestors in the mempool as
// possible) if we cannot fund the transaction otherwise.
if (wallet.m_spend_zero_conf_change) {
if (auto r3{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(0, 1, 2), available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) return r3;
if (auto r4{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(0, 1, std::min((size_t)4, max_ancestors/3), std::min((size_t)4, max_descendants/3)),
available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) {
return r4;
}
if (auto r5{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(0, 1, max_ancestors/2, max_descendants/2),
available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) {
return r5;
}
// If partial groups are allowed, relax the requirement of spending OutputGroups (groups
// of UTXOs sent to the same address, which are obviously controlled by a single wallet)
// in their entirety.
if (auto r6{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(0, 1, max_ancestors-1, max_descendants-1, /*include_partial=*/true),
available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) {
return r6;
}
// Try with unsafe inputs if they are allowed. This may spend unconfirmed outputs
// received from other wallets.
if (coin_control.m_include_unsafe_inputs) {
if (auto r7{AttemptSelection(wallet, value_to_select,
CoinEligibilityFilter(/*conf_mine=*/0, /*conf_theirs=*/0, max_ancestors-1, max_descendants-1, /*include_partial=*/true),
available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) {
return r7;
}
}
// Try with unlimited ancestors/descendants. The transaction will still need to meet
// mempool ancestor/descendant policy to be accepted to mempool and broadcasted, but
// OutputGroups use heuristics that may overestimate ancestor/descendant counts.
if (!fRejectLongChains) {
if (auto r8{AttemptSelection(wallet, value_to_select,
CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max(), std::numeric_limits<uint64_t>::max(), /*include_partial=*/true),
available_coins, coin_selection_params, /*allow_mixed_output_types=*/true)}) {
return r8;
}
}
}
// Coin Selection failed.
return std::optional<SelectionResult>();
}();
return res;
}
static bool IsCurrentForAntiFeeSniping(interfaces::Chain& chain, const uint256& block_hash)
{
if (chain.isInitialBlockDownload()) {
return false;
}
constexpr int64_t MAX_ANTI_FEE_SNIPING_TIP_AGE = 8 * 60 * 60; // in seconds
int64_t block_time;
CHECK_NONFATAL(chain.findBlock(block_hash, FoundBlock().time(block_time)));
if (block_time < (GetTime() - MAX_ANTI_FEE_SNIPING_TIP_AGE)) {
return false;
}
return true;
}
/**
* Set a height-based locktime for new transactions (uses the height of the
* current chain tip unless we are not synced with the current chain
*/
static void DiscourageFeeSniping(CMutableTransaction& tx, FastRandomContext& rng_fast,
interfaces::Chain& chain, const uint256& block_hash, int block_height)
{
// All inputs must be added by now
assert(!tx.vin.empty());
// Discourage fee sniping.
//
// For a large miner the value of the transactions in the best block and
// the mempool can exceed the cost of deliberately attempting to mine two
// blocks to orphan the current best block. By setting nLockTime such that
// only the next block can include the transaction, we discourage this
// practice as the height restricted and limited blocksize gives miners
// considering fee sniping fewer options for pulling off this attack.
//
// A simple way to think about this is from the wallet's point of view we
// always want the blockchain to move forward. By setting nLockTime this
// way we're basically making the statement that we only want this
// transaction to appear in the next block; we don't want to potentially
// encourage reorgs by allowing transactions to appear at lower heights
// than the next block in forks of the best chain.
//
// Of course, the subsidy is high enough, and transaction volume low
// enough, that fee sniping isn't a problem yet, but by implementing a fix
// now we ensure code won't be written that makes assumptions about
// nLockTime that preclude a fix later.
if (IsCurrentForAntiFeeSniping(chain, block_hash)) {
tx.nLockTime = block_height;
// Secondly occasionally randomly pick a nLockTime even further back, so
// that transactions that are delayed after signing for whatever reason,
// e.g. high-latency mix networks and some CoinJoin implementations, have
// better privacy.
if (rng_fast.randrange(10) == 0) {
tx.nLockTime = std::max(0, int(tx.nLockTime) - int(rng_fast.randrange(100)));
}
} else {
// If our chain is lagging behind, we can't discourage fee sniping nor help
// the privacy of high-latency transactions. To avoid leaking a potentially
// unique "nLockTime fingerprint", set nLockTime to a constant.
tx.nLockTime = 0;
}
// Sanity check all values
assert(tx.nLockTime < LOCKTIME_THRESHOLD); // Type must be block height
assert(tx.nLockTime <= uint64_t(block_height));
for (const auto& in : tx.vin) {
// Can not be FINAL for locktime to work
assert(in.nSequence != CTxIn::SEQUENCE_FINAL);
// May be MAX NONFINAL to disable both BIP68 and BIP125
if (in.nSequence == CTxIn::MAX_SEQUENCE_NONFINAL) continue;
// May be MAX BIP125 to disable BIP68 and enable BIP125
if (in.nSequence == MAX_BIP125_RBF_SEQUENCE) continue;
// The wallet does not support any other sequence-use right now.
assert(false);
}
}
static util::Result<CreatedTransactionResult> CreateTransactionInternal(
CWallet& wallet,
const std::vector<CRecipient>& vecSend,
int change_pos,
const CCoinControl& coin_control,
bool sign) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
{
AssertLockHeld(wallet.cs_wallet);
// out variables, to be packed into returned result structure
int nChangePosInOut = change_pos;
FastRandomContext rng_fast;
CMutableTransaction txNew; // The resulting transaction that we make
CoinSelectionParams coin_selection_params{rng_fast}; // Parameters for coin selection, init with dummy
coin_selection_params.m_avoid_partial_spends = coin_control.m_avoid_partial_spends;
// Set the long term feerate estimate to the wallet's consolidate feerate
coin_selection_params.m_long_term_feerate = wallet.m_consolidate_feerate;
CAmount recipients_sum = 0;
const OutputType change_type = wallet.TransactionChangeType(coin_control.m_change_type ? *coin_control.m_change_type : wallet.m_default_change_type, vecSend);
ReserveDestination reservedest(&wallet, change_type);
unsigned int outputs_to_subtract_fee_from = 0; // The number of outputs which we are subtracting the fee from
for (const auto& recipient : vecSend) {
recipients_sum += recipient.nAmount;
if (recipient.fSubtractFeeFromAmount) {
outputs_to_subtract_fee_from++;
coin_selection_params.m_subtract_fee_outputs = true;
}
}
// Create change script that will be used if we need change
CScript scriptChange;
bilingual_str error; // possible error str
// coin control: send change to custom address
if (!std::get_if<CNoDestination>(&coin_control.destChange)) {
scriptChange = GetScriptForDestination(coin_control.destChange);
} else { // no coin control: send change to newly generated address
// Note: We use a new key here to keep it from being obvious which side is the change.
// The drawback is that by not reusing a previous key, the change may be lost if a
// backup is restored, if the backup doesn't have the new private key for the change.
// If we reused the old key, it would be possible to add code to look for and
// rediscover unknown transactions that were written with keys of ours to recover
// post-backup change.
// Reserve a new key pair from key pool. If it fails, provide a dummy
// destination in case we don't need change.
CTxDestination dest;
auto op_dest = reservedest.GetReservedDestination(true);
if (!op_dest) {
error = _("Transaction needs a change address, but we can't generate it.") + Untranslated(" ") + util::ErrorString(op_dest);
} else {
dest = *op_dest;
scriptChange = GetScriptForDestination(dest);
}
// A valid destination implies a change script (and
// vice-versa). An empty change script will abort later, if the
// change keypool ran out, but change is required.
CHECK_NONFATAL(IsValidDestination(dest) != scriptChange.empty());
}
CTxOut change_prototype_txout(0, scriptChange);
coin_selection_params.change_output_size = GetSerializeSize(change_prototype_txout);
// Get size of spending the change output
int change_spend_size = CalculateMaximumSignedInputSize(change_prototype_txout, &wallet);
// If the wallet doesn't know how to sign change output, assume p2sh-p2wpkh
// as lower-bound to allow BnB to do it's thing
if (change_spend_size == -1) {
coin_selection_params.change_spend_size = DUMMY_NESTED_P2WPKH_INPUT_SIZE;
} else {
coin_selection_params.change_spend_size = (size_t)change_spend_size;
}
// Set discard feerate
coin_selection_params.m_discard_feerate = GetDiscardRate(wallet);
// Get the fee rate to use effective values in coin selection
FeeCalculation feeCalc;
coin_selection_params.m_effective_feerate = GetMinimumFeeRate(wallet, coin_control, &feeCalc);
// Do not, ever, assume that it's fine to change the fee rate if the user has explicitly
// provided one
if (coin_control.m_feerate && coin_selection_params.m_effective_feerate > *coin_control.m_feerate) {
return util::Error{strprintf(_("Fee rate (%s) is lower than the minimum fee rate setting (%s)"), coin_control.m_feerate->ToString(FeeEstimateMode::SAT_VB), coin_selection_params.m_effective_feerate.ToString(FeeEstimateMode::SAT_VB))};
}
if (feeCalc.reason == FeeReason::FALLBACK && !wallet.m_allow_fallback_fee) {
// eventually allow a fallback fee
return util::Error{_("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.")};
}
// Calculate the cost of change
// Cost of change is the cost of creating the change output + cost of spending the change output in the future.
// For creating the change output now, we use the effective feerate.
// For spending the change output in the future, we use the discard feerate for now.
// So cost of change = (change output size * effective feerate) + (size of spending change output * discard feerate)
coin_selection_params.m_change_fee = coin_selection_params.m_effective_feerate.GetFee(coin_selection_params.change_output_size);
coin_selection_params.m_cost_of_change = coin_selection_params.m_discard_feerate.GetFee(coin_selection_params.change_spend_size) + coin_selection_params.m_change_fee;
coin_selection_params.m_min_change_target = GenerateChangeTarget(std::floor(recipients_sum / vecSend.size()), coin_selection_params.m_change_fee, rng_fast);
// The smallest change amount should be:
// 1. at least equal to dust threshold
// 2. at least 1 sat greater than fees to spend it at m_discard_feerate
const auto dust = GetDustThreshold(change_prototype_txout, coin_selection_params.m_discard_feerate);
const auto change_spend_fee = coin_selection_params.m_discard_feerate.GetFee(coin_selection_params.change_spend_size);
coin_selection_params.min_viable_change = std::max(change_spend_fee + 1, dust);
// Static vsize overhead + outputs vsize. 4 nVersion, 4 nLocktime, 1 input count, 1 witness overhead (dummy, flag, stack size)
coin_selection_params.tx_noinputs_size = 10 + GetSizeOfCompactSize(vecSend.size()); // bytes for output count
// vouts to the payees
for (const auto& recipient : vecSend)
{
CTxOut txout(recipient.nAmount, recipient.scriptPubKey);
// Include the fee cost for outputs.
coin_selection_params.tx_noinputs_size += ::GetSerializeSize(txout, PROTOCOL_VERSION);
if (IsDust(txout, wallet.chain().relayDustFee())) {
return util::Error{_("Transaction amount too small")};
}
txNew.vout.push_back(txout);
}
// Include the fees for things that aren't inputs, excluding the change output
const CAmount not_input_fees = coin_selection_params.m_effective_feerate.GetFee(coin_selection_params.m_subtract_fee_outputs ? 0 : coin_selection_params.tx_noinputs_size);
CAmount selection_target = recipients_sum + not_input_fees;
// Fetch manually selected coins
PreSelectedInputs preset_inputs;
if (coin_control.HasSelected()) {
auto res_fetch_inputs = FetchSelectedInputs(wallet, coin_control, coin_selection_params);
if (!res_fetch_inputs) return util::Error{util::ErrorString(res_fetch_inputs)};
preset_inputs = *res_fetch_inputs;
}
// Fetch wallet available coins if "other inputs" are
// allowed (coins automatically selected by the wallet)
CoinsResult available_coins;
if (coin_control.m_allow_other_inputs) {
available_coins = AvailableCoins(wallet, &coin_control, coin_selection_params.m_effective_feerate);
}
// Choose coins to use
std::optional<SelectionResult> result = SelectCoins(wallet, available_coins, preset_inputs, /*nTargetValue=*/selection_target, coin_control, coin_selection_params);
if (!result) {
return util::Error{_("Insufficient funds")};
}
TRACE5(coin_selection, selected_coins, wallet.GetName().c_str(), GetAlgorithmName(result->GetAlgo()).c_str(), result->GetTarget(), result->GetWaste(), result->GetSelectedValue());
const CAmount change_amount = result->GetChange(coin_selection_params.min_viable_change, coin_selection_params.m_change_fee);
if (change_amount > 0) {
CTxOut newTxOut(change_amount, scriptChange);
if (nChangePosInOut == -1) {
// Insert change txn at random position:
nChangePosInOut = rng_fast.randrange(txNew.vout.size() + 1);
} else if ((unsigned int)nChangePosInOut > txNew.vout.size()) {
return util::Error{_("Transaction change output index out of range")};
}
txNew.vout.insert(txNew.vout.begin() + nChangePosInOut, newTxOut);
} else {
nChangePosInOut = -1;
}
// Shuffle selected coins and fill in final vin
std::vector<COutput> selected_coins = result->GetShuffledInputVector();
// The sequence number is set to non-maxint so that DiscourageFeeSniping
// works.
//
// BIP125 defines opt-in RBF as any nSequence < maxint-1, so
// we use the highest possible value in that range (maxint-2)
// to avoid conflicting with other possible uses of nSequence,
// and in the spirit of "smallest possible change from prior
// behavior."
const uint32_t nSequence{coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf) ? MAX_BIP125_RBF_SEQUENCE : CTxIn::MAX_SEQUENCE_NONFINAL};
for (const auto& coin : selected_coins) {
txNew.vin.push_back(CTxIn(coin.outpoint, CScript(), nSequence));
}
DiscourageFeeSniping(txNew, rng_fast, wallet.chain(), wallet.GetLastBlockHash(), wallet.GetLastBlockHeight());
// Calculate the transaction fee
TxSize tx_sizes = CalculateMaximumSignedTxSize(CTransaction(txNew), &wallet, &coin_control);
int nBytes = tx_sizes.vsize;
if (nBytes == -1) {
return util::Error{_("Missing solving data for estimating transaction size")};
}
CAmount fee_needed = coin_selection_params.m_effective_feerate.GetFee(nBytes);
const CAmount output_value = CalculateOutputValue(txNew);
Assume(recipients_sum + change_amount == output_value);
CAmount current_fee = result->GetSelectedValue() - output_value;
// Sanity check that the fee cannot be negative as that means we have more output value than input value
if (current_fee < 0) {
return util::Error{Untranslated(STR_INTERNAL_BUG("Fee paid < 0"))};
}
// If there is a change output and we overpay the fees then increase the change to match the fee needed
if (nChangePosInOut != -1 && fee_needed < current_fee) {
auto& change = txNew.vout.at(nChangePosInOut);
change.nValue += current_fee - fee_needed;
current_fee = result->GetSelectedValue() - CalculateOutputValue(txNew);
if (fee_needed != current_fee) {
return util::Error{Untranslated(STR_INTERNAL_BUG("Change adjustment: Fee needed != fee paid"))};
}
}
// Reduce output values for subtractFeeFromAmount
if (coin_selection_params.m_subtract_fee_outputs) {
CAmount to_reduce = fee_needed - current_fee;
int i = 0;
bool fFirst = true;
for (const auto& recipient : vecSend)
{
if (i == nChangePosInOut) {
++i;
}
CTxOut& txout = txNew.vout[i];
if (recipient.fSubtractFeeFromAmount)
{
txout.nValue -= to_reduce / outputs_to_subtract_fee_from; // Subtract fee equally from each selected recipient
if (fFirst) // first receiver pays the remainder not divisible by output count
{
fFirst = false;
txout.nValue -= to_reduce % outputs_to_subtract_fee_from;
}
// Error if this output is reduced to be below dust
if (IsDust(txout, wallet.chain().relayDustFee())) {
if (txout.nValue < 0) {
return util::Error{_("The transaction amount is too small to pay the fee")};
} else {
return util::Error{_("The transaction amount is too small to send after the fee has been deducted")};
}
}
}
++i;
}
current_fee = result->GetSelectedValue() - CalculateOutputValue(txNew);
if (fee_needed != current_fee) {
return util::Error{Untranslated(STR_INTERNAL_BUG("SFFO: Fee needed != fee paid"))};
}
}
// fee_needed should now always be less than or equal to the current fees that we pay.
// If it is not, it is a bug.
if (fee_needed > current_fee) {
return util::Error{Untranslated(STR_INTERNAL_BUG("Fee needed > fee paid"))};
}
// Give up if change keypool ran out and change is required
if (scriptChange.empty() && nChangePosInOut != -1) {
return util::Error{error};
}
if (sign && !wallet.SignTransaction(txNew)) {
return util::Error{_("Signing transaction failed")};
}
// Return the constructed transaction data.
CTransactionRef tx = MakeTransactionRef(std::move(txNew));
// Limit size
if ((sign && GetTransactionWeight(*tx) > MAX_STANDARD_TX_WEIGHT) ||
(!sign && tx_sizes.weight > MAX_STANDARD_TX_WEIGHT))
{
return util::Error{_("Transaction too large")};
}
if (current_fee > wallet.m_default_max_tx_fee) {
return util::Error{TransactionErrorString(TransactionError::MAX_FEE_EXCEEDED)};
}
if (gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS)) {
// Lastly, ensure this tx will pass the mempool's chain limits
if (!wallet.chain().checkChainLimits(tx)) {
return util::Error{_("Transaction has too long of a mempool chain")};
}
}
// Before we return success, we assume any change key will be used to prevent
// accidental re-use.
reservedest.KeepDestination();
wallet.WalletLogPrintf("Fee Calculation: Fee:%d Bytes:%u Tgt:%d (requested %d) Reason:\"%s\" Decay %.5f: Estimation: (%g - %g) %.2f%% %.1f/(%.1f %d mem %.1f out) Fail: (%g - %g) %.2f%% %.1f/(%.1f %d mem %.1f out)\n",
current_fee, nBytes, feeCalc.returnedTarget, feeCalc.desiredTarget, StringForFeeReason(feeCalc.reason), feeCalc.est.decay,
feeCalc.est.pass.start, feeCalc.est.pass.end,
(feeCalc.est.pass.totalConfirmed + feeCalc.est.pass.inMempool + feeCalc.est.pass.leftMempool) > 0.0 ? 100 * feeCalc.est.pass.withinTarget / (feeCalc.est.pass.totalConfirmed + feeCalc.est.pass.inMempool + feeCalc.est.pass.leftMempool) : 0.0,
feeCalc.est.pass.withinTarget, feeCalc.est.pass.totalConfirmed, feeCalc.est.pass.inMempool, feeCalc.est.pass.leftMempool,
feeCalc.est.fail.start, feeCalc.est.fail.end,
(feeCalc.est.fail.totalConfirmed + feeCalc.est.fail.inMempool + feeCalc.est.fail.leftMempool) > 0.0 ? 100 * feeCalc.est.fail.withinTarget / (feeCalc.est.fail.totalConfirmed + feeCalc.est.fail.inMempool + feeCalc.est.fail.leftMempool) : 0.0,
feeCalc.est.fail.withinTarget, feeCalc.est.fail.totalConfirmed, feeCalc.est.fail.inMempool, feeCalc.est.fail.leftMempool);
return CreatedTransactionResult(tx, current_fee, nChangePosInOut, feeCalc);
}
util::Result<CreatedTransactionResult> CreateTransaction(
CWallet& wallet,
const std::vector<CRecipient>& vecSend,
int change_pos,
const CCoinControl& coin_control,
bool sign)
{
if (vecSend.empty()) {
return util::Error{_("Transaction must have at least one recipient")};
}
if (std::any_of(vecSend.cbegin(), vecSend.cend(), [](const auto& recipient){ return recipient.nAmount < 0; })) {
return util::Error{_("Transaction amounts must not be negative")};
}
LOCK(wallet.cs_wallet);
auto res = CreateTransactionInternal(wallet, vecSend, change_pos, coin_control, sign);
TRACE4(coin_selection, normal_create_tx_internal, wallet.GetName().c_str(), bool(res),
res ? res->fee : 0, res ? res->change_pos : 0);
if (!res) return res;
const auto& txr_ungrouped = *res;
// try with avoidpartialspends unless it's enabled already
if (txr_ungrouped.fee > 0 /* 0 means non-functional fee rate estimation */ && wallet.m_max_aps_fee > -1 && !coin_control.m_avoid_partial_spends) {
TRACE1(coin_selection, attempting_aps_create_tx, wallet.GetName().c_str());
CCoinControl tmp_cc = coin_control;
tmp_cc.m_avoid_partial_spends = true;
auto txr_grouped = CreateTransactionInternal(wallet, vecSend, change_pos, tmp_cc, sign);
// if fee of this alternative one is within the range of the max fee, we use this one
const bool use_aps{txr_grouped.has_value() ? (txr_grouped->fee <= txr_ungrouped.fee + wallet.m_max_aps_fee) : false};
TRACE5(coin_selection, aps_create_tx_internal, wallet.GetName().c_str(), use_aps, txr_grouped.has_value(),
txr_grouped.has_value() ? txr_grouped->fee : 0, txr_grouped.has_value() ? txr_grouped->change_pos : 0);
if (txr_grouped) {
wallet.WalletLogPrintf("Fee non-grouped = %lld, grouped = %lld, using %s\n",
txr_ungrouped.fee, txr_grouped->fee, use_aps ? "grouped" : "non-grouped");
if (use_aps) return txr_grouped;
}
}
return res;
}
bool FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& nFeeRet, int& nChangePosInOut, bilingual_str& error, bool lockUnspents, const std::set<int>& setSubtractFeeFromOutputs, CCoinControl coinControl)
{
std::vector<CRecipient> vecSend;
// Turn the txout set into a CRecipient vector.
for (size_t idx = 0; idx < tx.vout.size(); idx++) {
const CTxOut& txOut = tx.vout[idx];
CRecipient recipient = {txOut.scriptPubKey, txOut.nValue, setSubtractFeeFromOutputs.count(idx) == 1};
vecSend.push_back(recipient);
}
// Acquire the locks to prevent races to the new locked unspents between the
// CreateTransaction call and LockCoin calls (when lockUnspents is true).
LOCK(wallet.cs_wallet);
// Fetch specified UTXOs from the UTXO set to get the scriptPubKeys and values of the outputs being selected
// and to match with the given solving_data. Only used for non-wallet outputs.
std::map<COutPoint, Coin> coins;
for (const CTxIn& txin : tx.vin) {
coins[txin.prevout]; // Create empty map entry keyed by prevout.
}
wallet.chain().findCoins(coins);
for (const CTxIn& txin : tx.vin) {
const auto& outPoint = txin.prevout;
if (wallet.IsMine(outPoint)) {
// The input was found in the wallet, so select as internal
coinControl.Select(outPoint);
} else if (coins[outPoint].out.IsNull()) {
error = _("Unable to find UTXO for external input");
return false;
} else {
// The input was not in the wallet, but is in the UTXO set, so select as external
coinControl.SelectExternal(outPoint, coins[outPoint].out);
}
}
auto res = CreateTransaction(wallet, vecSend, nChangePosInOut, coinControl, false);
if (!res) {
error = util::ErrorString(res);
return false;
}
const auto& txr = *res;
CTransactionRef tx_new = txr.tx;
nFeeRet = txr.fee;
nChangePosInOut = txr.change_pos;
if (nChangePosInOut != -1) {
tx.vout.insert(tx.vout.begin() + nChangePosInOut, tx_new->vout[nChangePosInOut]);
}
// Copy output sizes from new transaction; they may have had the fee
// subtracted from them.
for (unsigned int idx = 0; idx < tx.vout.size(); idx++) {
tx.vout[idx].nValue = tx_new->vout[idx].nValue;
}
// Add new txins while keeping original txin scriptSig/order.
for (const CTxIn& txin : tx_new->vin) {
if (!coinControl.IsSelected(txin.prevout)) {
tx.vin.push_back(txin);
}
if (lockUnspents) {
wallet.LockCoin(txin.prevout);
}
}
return true;
}
} // namespace wallet
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