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bitcoin/src/wallet/spend.cpp
MarcoFalke c561f2f06e
Merge bitcoin/bitcoin#23497: Add src/node/ and src/wallet/ code to node:: and wallet:: namespaces 
e5b6aef612 Move CBlockFileInfo::ToString method where class is declared (Russell Yanofsky)
f7086fd8ff Add src/wallet/* code to wallet:: namespace (Russell Yanofsky)
90fc8b089d Add src/node/* code to node:: namespace (Russell Yanofsky)

Pull request description:

  There are no code changes, this is just adding `namespace` and `using` declarations and `node::` or `wallet::` qualifiers in some places.

  Motivations for this change are:

  - To make it easier to see when node and wallet code is being accessed places where it shouldn't be. For example if GUI code is accessing node and wallet internals or if wallet and node code are referencing each other.
  - To make source code organization clearer ([#15732](https://github.com/bitcoin/bitcoin/issues/15732)), being able to know that `wallet::` code is in `src/wallet/`, `node::` code is in `src/node/`, `init::` code is in `src/init/`, `util::` code is in `src/util/`, etc.

  Reviewing with `git log -p -n1 -U0 --word-diff-regex=.` can be helpful to verify this is only updating declarations, not changing code.

ACKs for top commit:
  achow101:
    ACK e5b6aef612
  MarcoFalke:
    Concept ACK e5b6aef612 🍨

Tree-SHA512: 3797745c90246794e2d55a2ee6e8b0ad5c811e4e03a242d3fdfeb68032f8787f0d48ed4097f6b7730f540220c0af99ef423cd9dbe7f76b2ec12e769a757a2c8d
2022-01-11 11:11:00 +01:00

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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 <consensus/amount.h>
#include <consensus/validation.h>
#include <interfaces/chain.h>
#include <policy/policy.h>
#include <script/signingprovider.h>
#include <util/check.h>
#include <util/fees.h>
#include <util/moneystr.h>
#include <util/rbf.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>
using interfaces::FoundBlock;
namespace wallet {
static constexpr size_t OUTPUT_GROUP_MAX_ENTRIES{100};
int GetTxSpendSize(const CWallet& wallet, const CWalletTx& wtx, unsigned int out, bool use_max_sig)
{
return CalculateMaximumSignedInputSize(wtx.tx->vout[out], &wallet, use_max_sig);
}
std::string COutput::ToString() const
{
return strprintf("COutput(%s, %d, %d) [%s]", tx->GetHash().ToString(), i, nDepth, FormatMoney(tx->tx->vout[i].nValue));
}
int CalculateMaximumSignedInputSize(const CTxOut& txout, const SigningProvider* provider, bool use_max_sig)
{
CMutableTransaction txn;
txn.vin.push_back(CTxIn(COutPoint()));
if (!provider || !DummySignInput(*provider, txn.vin[0], txout, use_max_sig)) {
return -1;
}
return GetVirtualTransactionInputSize(txn.vin[0]);
}
int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* wallet, bool use_max_sig)
{
const std::unique_ptr<SigningProvider> provider = wallet->GetSolvingProvider(txout.scriptPubKey);
return CalculateMaximumSignedInputSize(txout, provider.get(), use_max_sig);
}
// 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);
}
void AvailableCoins(const CWallet& wallet, std::vector<COutput>& vCoins, const CCoinControl* coinControl, const CAmount& nMinimumAmount, const CAmount& nMaximumAmount, const CAmount& nMinimumSumAmount, const uint64_t nMaximumCount)
{
AssertLockHeld(wallet.cs_wallet);
vCoins.clear();
CAmount nTotal = 0;
// 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.chain().checkFinalTx(*wtx.tx)) {
continue;
}
if (wallet.IsTxImmatureCoinBase(wtx))
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;
}
for (unsigned int i = 0; i < wtx.tx->vout.size(); i++) {
// Only consider selected coins if add_inputs is false
if (coinControl && !coinControl->m_add_inputs && !coinControl->IsSelected(COutPoint(entry.first, i))) {
continue;
}
if (wtx.tx->vout[i].nValue < nMinimumAmount || wtx.tx->vout[i].nValue > nMaximumAmount)
continue;
if (coinControl && coinControl->HasSelected() && !coinControl->fAllowOtherInputs && !coinControl->IsSelected(COutPoint(entry.first, i)))
continue;
if (wallet.IsLockedCoin(entry.first, i))
continue;
if (wallet.IsSpent(wtxid, i))
continue;
isminetype mine = wallet.IsMine(wtx.tx->vout[i]);
if (mine == ISMINE_NO) {
continue;
}
if (!allow_used_addresses && wallet.IsSpentKey(wtxid, i)) {
continue;
}
std::unique_ptr<SigningProvider> provider = wallet.GetSolvingProvider(wtx.tx->vout[i].scriptPubKey);
bool solvable = provider ? IsSolvable(*provider, wtx.tx->vout[i].scriptPubKey) : false;
bool spendable = ((mine & ISMINE_SPENDABLE) != ISMINE_NO) || (((mine & ISMINE_WATCH_ONLY) != ISMINE_NO) && (coinControl && coinControl->fAllowWatchOnly && solvable));
vCoins.push_back(COutput(wallet, wtx, i, nDepth, spendable, solvable, safeTx, (coinControl && coinControl->fAllowWatchOnly)));
// Checks the sum amount of all UTXO's.
if (nMinimumSumAmount != MAX_MONEY) {
nTotal += wtx.tx->vout[i].nValue;
if (nTotal >= nMinimumSumAmount) {
return;
}
}
// Checks the maximum number of UTXO's.
if (nMaximumCount > 0 && vCoins.size() >= nMaximumCount) {
return;
}
}
}
}
CAmount GetAvailableBalance(const CWallet& wallet, const CCoinControl* coinControl)
{
LOCK(wallet.cs_wallet);
CAmount balance = 0;
std::vector<COutput> vCoins;
AvailableCoins(wallet, vCoins, coinControl);
for (const COutput& out : vCoins) {
if (out.fSpendable) {
balance += out.tx->tx->vout[out.i].nValue;
}
}
return balance;
}
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];
}
std::map<CTxDestination, std::vector<COutput>> ListCoins(const CWallet& wallet)
{
AssertLockHeld(wallet.cs_wallet);
std::map<CTxDestination, std::vector<COutput>> result;
std::vector<COutput> availableCoins;
AvailableCoins(wallet, availableCoins);
for (const COutput& coin : availableCoins) {
CTxDestination address;
if ((coin.fSpendable || (wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && coin.fSolvable)) &&
ExtractDestination(FindNonChangeParentOutput(wallet, *coin.tx->tx, coin.i).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()) {
int depth = wallet.GetTxDepthInMainChain(it->second);
if (depth >= 0 && output.n < it->second.tx->vout.size() &&
wallet.IsMine(it->second.tx->vout[output.n]) == is_mine_filter
) {
CTxDestination address;
if (ExtractDestination(FindNonChangeParentOutput(wallet, *it->second.tx, output.n).scriptPubKey, address)) {
result[address].emplace_back(
wallet, it->second, output.n, depth, true /* spendable */, true /* solvable */, false /* safe */);
}
}
}
}
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.fSpendable) continue;
size_t ancestors, descendants;
wallet.chain().getTransactionAncestry(output.tx->GetHash(), ancestors, descendants);
CInputCoin input_coin = output.GetInputCoin();
// Make an OutputGroup containing just this output
OutputGroup group{coin_sel_params};
group.Insert(input_coin, output.nDepth, CachedTxIsFromMe(wallet, *output.tx, ISMINE_ALL), 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's CInputCoin is added
// to the last OutputGroup in the vector for the scriptPubKey. When the last OutputGroup has
// OUTPUT_GROUP_MAX_ENTRIES CInputCoins, 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.fSpendable) continue;
size_t ancestors, descendants;
wallet.chain().getTransactionAncestry(output.tx->GetHash(), ancestors, descendants);
CInputCoin input_coin = output.GetInputCoin();
CScript spk = input_coin.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 CInputCoin 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 input_coin to group
group->Insert(input_coin, output.nDepth, CachedTxIsFromMe(wallet, *output.tx, ISMINE_ALL), 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, std::vector<COutput> coins,
const CoinSelectionParams& coin_selection_params)
{
// Vector of results. We will choose the best one based on waste.
std::vector<SelectionResult> results;
// Note that unlike KnapsackSolver, we do not include the fee for creating a change output as BnB will not create a change output.
std::vector<OutputGroup> positive_groups = GroupOutputs(wallet, coins, coin_selection_params, eligibility_filter, true /* positive_only */);
if (auto bnb_result{SelectCoinsBnB(positive_groups, nTargetValue, coin_selection_params.m_cost_of_change)}) {
bnb_result->ComputeAndSetWaste(CAmount(0));
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, coins, coin_selection_params, eligibility_filter, false /* positive_only */);
// While nTargetValue includes the transaction fees for non-input things, it does not include the fee for creating a change output.
// So we need to include that for KnapsackSolver as well, as we are expecting to create a change output.
if (auto knapsack_result{KnapsackSolver(all_groups, nTargetValue + coin_selection_params.m_change_fee)}) {
knapsack_result->ComputeAndSetWaste(coin_selection_params.m_cost_of_change);
results.push_back(*knapsack_result);
}
// We include the minimum final change for SRD as we do want to avoid making really small change.
// KnapsackSolver does not need this because it includes MIN_CHANGE internally.
const CAmount srd_target = nTargetValue + coin_selection_params.m_change_fee + MIN_FINAL_CHANGE;
if (auto srd_result{SelectCoinsSRD(positive_groups, srd_target)}) {
srd_result->ComputeAndSetWaste(coin_selection_params.m_cost_of_change);
results.push_back(*srd_result);
}
if (results.size() == 0) {
// No solution found
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(results.begin(), results.end());
return best_result;
}
std::optional<SelectionResult> SelectCoins(const CWallet& wallet, const std::vector<COutput>& vAvailableCoins, const CAmount& nTargetValue, const CCoinControl& coin_control, const CoinSelectionParams& coin_selection_params)
{
std::vector<COutput> vCoins(vAvailableCoins);
CAmount value_to_select = nTargetValue;
OutputGroup preset_inputs(coin_selection_params);
// coin control -> return all selected outputs (we want all selected to go into the transaction for sure)
if (coin_control.HasSelected() && !coin_control.fAllowOtherInputs)
{
for (const COutput& out : vCoins) {
if (!out.fSpendable) continue;
/* Set depth, from_me, ancestors, and descendants to 0 or false as these don't matter for preset inputs as no actual selection is being done.
* positive_only is set to false because we want to include all preset inputs, even if they are dust.
*/
preset_inputs.Insert(out.GetInputCoin(), 0, false, 0, 0, false);
}
SelectionResult result(nTargetValue);
result.AddInput(preset_inputs);
if (result.GetSelectedValue() < nTargetValue) return std::nullopt;
return result;
}
// calculate value from preset inputs and store them
std::set<CInputCoin> setPresetCoins;
std::vector<COutPoint> vPresetInputs;
coin_control.ListSelected(vPresetInputs);
for (const COutPoint& outpoint : vPresetInputs) {
int input_bytes = -1;
CTxOut txout;
std::map<uint256, CWalletTx>::const_iterator it = wallet.mapWallet.find(outpoint.hash);
if (it != wallet.mapWallet.end()) {
const CWalletTx& wtx = it->second;
// Clearly invalid input, fail
if (wtx.tx->vout.size() <= outpoint.n) {
return std::nullopt;
}
input_bytes = GetTxSpendSize(wallet, wtx, outpoint.n, false);
txout = wtx.tx->vout.at(outpoint.n);
}
if (input_bytes == -1) {
// The input is external. We either did not find the tx in mapWallet, or we did but couldn't compute the input size with wallet data
if (!coin_control.GetExternalOutput(outpoint, txout)) {
// Not ours, and we don't have solving data.
return std::nullopt;
}
input_bytes = CalculateMaximumSignedInputSize(txout, &coin_control.m_external_provider, /* use_max_sig */ true);
}
CInputCoin coin(outpoint, txout, input_bytes);
if (coin.m_input_bytes == -1) {
return std::nullopt; // Not solvable, can't estimate size for fee
}
coin.effective_value = coin.txout.nValue - coin_selection_params.m_effective_feerate.GetFee(coin.m_input_bytes);
if (coin_selection_params.m_subtract_fee_outputs) {
value_to_select -= coin.txout.nValue;
} else {
value_to_select -= coin.effective_value;
}
setPresetCoins.insert(coin);
/* Set depth, from_me, ancestors, and descendants to 0 or false as don't matter for preset inputs as no actual selection is being done.
* positive_only is set to false because we want to include all preset inputs, even if they are dust.
*/
preset_inputs.Insert(coin, 0, false, 0, 0, false);
}
// remove preset inputs from vCoins so that Coin Selection doesn't pick them.
for (std::vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coin_control.HasSelected();)
{
if (setPresetCoins.count(it->GetInputCoin()))
it = vCoins.erase(it);
else
++it;
}
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 && vCoins.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
Shuffle(vCoins.begin(), vCoins.end(), FastRandomContext());
}
// 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 = [&] {
// Pre-selected inputs already cover the target amount.
if (value_to_select <= 0) return std::make_optional(SelectionResult(nTargetValue));
// 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), vCoins, coin_selection_params)}) return r1;
if (auto r2{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(1, 1, 0), vCoins, coin_selection_params)}) 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), vCoins, coin_selection_params)}) 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)),
vCoins, coin_selection_params)}) {
return r4;
}
if (auto r5{AttemptSelection(wallet, value_to_select, CoinEligibilityFilter(0, 1, max_ancestors/2, max_descendants/2),
vCoins, coin_selection_params)}) {
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, true /* include_partial_groups */),
vCoins, coin_selection_params)}) {
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(0 /* conf_mine */, 0 /* conf_theirs */, max_ancestors-1, max_descendants-1, true /* include_partial_groups */),
vCoins, coin_selection_params)}) {
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(), true /* include_partial_groups */),
vCoins, coin_selection_params)}) {
return r8;
}
}
}
// Coin Selection failed.
return std::optional<SelectionResult>();
}();
if (!res) return std::nullopt;
// Add preset inputs to result
res->AddInput(preset_inputs);
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;
}
/**
* Return 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 uint32_t GetLocktimeForNewTransaction(interfaces::Chain& chain, const uint256& block_hash, int block_height)
{
uint32_t locktime;
// 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)) {
locktime = 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 (GetRandInt(10) == 0)
locktime = std::max(0, (int)locktime - GetRandInt(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.
locktime = 0;
}
assert(locktime < LOCKTIME_THRESHOLD);
return locktime;
}
static bool CreateTransactionInternal(
CWallet& wallet,
const std::vector<CRecipient>& vecSend,
CTransactionRef& tx,
CAmount& nFeeRet,
int& nChangePosInOut,
bilingual_str& error,
const CCoinControl& coin_control,
FeeCalculation& fee_calc_out,
bool sign) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
{
AssertLockHeld(wallet.cs_wallet);
CMutableTransaction txNew; // The resulting transaction that we make
txNew.nLockTime = GetLocktimeForNewTransaction(wallet.chain(), wallet.GetLastBlockHash(), wallet.GetLastBlockHeight());
CoinSelectionParams coin_selection_params; // 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;
// 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;
bilingual_str dest_err;
if (!reservedest.GetReservedDestination(dest, true, dest_err)) {
error = _("Transaction needs a change address, but we can't generate it.") + Untranslated(" ") + dest_err;
}
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) {
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));
return false;
}
if (feeCalc.reason == FeeReason::FALLBACK && !wallet.m_allow_fallback_fee) {
// eventually allow a fallback fee
error = _("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.");
return false;
}
// 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;
// vouts to the payees
if (!coin_selection_params.m_subtract_fee_outputs) {
coin_selection_params.tx_noinputs_size = 11; // Static vsize overhead + outputs vsize. 4 nVersion, 4 nLocktime, 1 input count, 1 output count, 1 witness overhead (dummy, flag, stack size)
}
for (const auto& recipient : vecSend)
{
CTxOut txout(recipient.nAmount, recipient.scriptPubKey);
// Include the fee cost for outputs.
if (!coin_selection_params.m_subtract_fee_outputs) {
coin_selection_params.tx_noinputs_size += ::GetSerializeSize(txout, PROTOCOL_VERSION);
}
if (IsDust(txout, wallet.chain().relayDustFee()))
{
error = _("Transaction amount too small");
return false;
}
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.tx_noinputs_size);
CAmount selection_target = recipients_sum + not_input_fees;
// Get available coins
std::vector<COutput> vAvailableCoins;
AvailableCoins(wallet, vAvailableCoins, &coin_control, 1, MAX_MONEY, MAX_MONEY, 0);
// Choose coins to use
std::optional<SelectionResult> result = SelectCoins(wallet, vAvailableCoins, /* nTargetValue */ selection_target, coin_control, coin_selection_params);
if (!result) {
error = _("Insufficient funds");
return false;
}
// Always make a change output
// We will reduce the fee from this change output later, and remove the output if it is too small.
const CAmount change_and_fee = result->GetSelectedValue() - recipients_sum;
assert(change_and_fee >= 0);
CTxOut newTxOut(change_and_fee, scriptChange);
if (nChangePosInOut == -1)
{
// Insert change txn at random position:
nChangePosInOut = GetRandInt(txNew.vout.size()+1);
}
else if ((unsigned int)nChangePosInOut > txNew.vout.size())
{
error = _("Change index out of range");
return false;
}
assert(nChangePosInOut != -1);
auto change_position = txNew.vout.insert(txNew.vout.begin() + nChangePosInOut, newTxOut);
// Shuffle selected coins and fill in final vin
std::vector<CInputCoin> selected_coins = result->GetShuffledInputVector();
// Note how the sequence number is set to non-maxint so that
// the nLockTime set above actually 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::SEQUENCE_FINAL - 1);
for (const auto& coin : selected_coins) {
txNew.vin.push_back(CTxIn(coin.outpoint, CScript(), nSequence));
}
// Calculate the transaction fee
TxSize tx_sizes = CalculateMaximumSignedTxSize(CTransaction(txNew), &wallet, &coin_control);
int nBytes = tx_sizes.vsize;
if (nBytes == -1) {
error = _("Missing solving data for estimating transaction size");
return false;
}
nFeeRet = coin_selection_params.m_effective_feerate.GetFee(nBytes);
// Subtract fee from the change output if not subtracting it from recipient outputs
CAmount fee_needed = nFeeRet;
if (!coin_selection_params.m_subtract_fee_outputs) {
change_position->nValue -= fee_needed;
}
// We want to drop the change to fees if:
// 1. The change output would be dust
// 2. The change is within the (almost) exact match window, i.e. it is less than or equal to the cost of the change output (cost_of_change)
CAmount change_amount = change_position->nValue;
if (IsDust(*change_position, coin_selection_params.m_discard_feerate) || change_amount <= coin_selection_params.m_cost_of_change)
{
nChangePosInOut = -1;
change_amount = 0;
txNew.vout.erase(change_position);
// Because we have dropped this change, the tx size and required fee will be different, so let's recalculate those
tx_sizes = CalculateMaximumSignedTxSize(CTransaction(txNew), &wallet, &coin_control);
nBytes = tx_sizes.vsize;
fee_needed = coin_selection_params.m_effective_feerate.GetFee(nBytes);
}
// The only time that fee_needed should be less than the amount available for fees (in change_and_fee - change_amount) is when
// we are subtracting the fee from the outputs. If this occurs at any other time, it is a bug.
assert(coin_selection_params.m_subtract_fee_outputs || fee_needed <= change_and_fee - change_amount);
// Update nFeeRet in case fee_needed changed due to dropping the change output
if (fee_needed <= change_and_fee - change_amount) {
nFeeRet = change_and_fee - change_amount;
}
// Reduce output values for subtractFeeFromAmount
if (coin_selection_params.m_subtract_fee_outputs) {
CAmount to_reduce = fee_needed + change_amount - change_and_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) {
error = _("The transaction amount is too small to pay the fee");
} else {
error = _("The transaction amount is too small to send after the fee has been deducted");
}
return false;
}
}
++i;
}
nFeeRet = fee_needed;
}
// Give up if change keypool ran out and change is required
if (scriptChange.empty() && nChangePosInOut != -1) {
return false;
}
if (sign && !wallet.SignTransaction(txNew)) {
error = _("Signing transaction failed");
return false;
}
// Return the constructed transaction data.
tx = MakeTransactionRef(std::move(txNew));
// Limit size
if ((sign && GetTransactionWeight(*tx) > MAX_STANDARD_TX_WEIGHT) ||
(!sign && tx_sizes.weight > MAX_STANDARD_TX_WEIGHT))
{
error = _("Transaction too large");
return false;
}
if (nFeeRet > wallet.m_default_max_tx_fee) {
error = TransactionErrorString(TransactionError::MAX_FEE_EXCEEDED);
return false;
}
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)) {
error = _("Transaction has too long of a mempool chain");
return false;
}
}
// Before we return success, we assume any change key will be used to prevent
// accidental re-use.
reservedest.KeepDestination();
fee_calc_out = feeCalc;
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",
nFeeRet, 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 true;
}
bool CreateTransaction(
CWallet& wallet,
const std::vector<CRecipient>& vecSend,
CTransactionRef& tx,
CAmount& nFeeRet,
int& nChangePosInOut,
bilingual_str& error,
const CCoinControl& coin_control,
FeeCalculation& fee_calc_out,
bool sign)
{
if (vecSend.empty()) {
error = _("Transaction must have at least one recipient");
return false;
}
if (std::any_of(vecSend.cbegin(), vecSend.cend(), [](const auto& recipient){ return recipient.nAmount < 0; })) {
error = _("Transaction amounts must not be negative");
return false;
}
LOCK(wallet.cs_wallet);
int nChangePosIn = nChangePosInOut;
Assert(!tx); // tx is an out-param. TODO change the return type from bool to tx (or nullptr)
bool res = CreateTransactionInternal(wallet, vecSend, tx, nFeeRet, nChangePosInOut, error, coin_control, fee_calc_out, sign);
// try with avoidpartialspends unless it's enabled already
if (res && nFeeRet > 0 /* 0 means non-functional fee rate estimation */ && wallet.m_max_aps_fee > -1 && !coin_control.m_avoid_partial_spends) {
CCoinControl tmp_cc = coin_control;
tmp_cc.m_avoid_partial_spends = true;
CAmount nFeeRet2;
CTransactionRef tx2;
int nChangePosInOut2 = nChangePosIn;
bilingual_str error2; // fired and forgotten; if an error occurs, we discard the results
if (CreateTransactionInternal(wallet, vecSend, tx2, nFeeRet2, nChangePosInOut2, error2, tmp_cc, fee_calc_out, sign)) {
// if fee of this alternative one is within the range of the max fee, we use this one
const bool use_aps = nFeeRet2 <= nFeeRet + wallet.m_max_aps_fee;
wallet.WalletLogPrintf("Fee non-grouped = %lld, grouped = %lld, using %s\n", nFeeRet, nFeeRet2, use_aps ? "grouped" : "non-grouped");
if (use_aps) {
tx = tx2;
nFeeRet = nFeeRet2;
nChangePosInOut = nChangePosInOut2;
}
}
}
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);
}
coinControl.fAllowOtherInputs = true;
for (const CTxIn& txin : tx.vin) {
coinControl.Select(txin.prevout);
}
// 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);
CTransactionRef tx_new;
FeeCalculation fee_calc_out;
if (!CreateTransaction(wallet, vecSend, tx_new, nFeeRet, nChangePosInOut, error, coinControl, fee_calc_out, false)) {
return false;
}
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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