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src/wallet/spend.cpp
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merge-script
Merge bitcoin/bitcoin#35501: wallet: store all witness variants of a transaction
05 авг 2026, 00:04
Не верифицирован
05 авг 2026, 00:04
d3cfd02
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// Copyright (c) 2021-present 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 <common/args.h> #include <common/messages.h> #include <common/system.h> #include <consensus/amount.h> #include <consensus/validation.h> #include <interfaces/chain.h> #include <node/types.h> #include <numeric> #include <policy/policy.h> #include <policy/truc_policy.h> #include <primitives/transaction.h> #include <primitives/transaction_identifier.h> #include <script/script.h> #include <script/signingprovider.h> #include <script/solver.h> #include <util/check.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 common::StringForFeeReason; using common::TransactionErrorString; using interfaces::FoundBlock; using node::TransactionError; TRACEPOINT_SEMAPHORE(coin_selection, selected_coins); TRACEPOINT_SEMAPHORE(coin_selection, normal_create_tx_internal); TRACEPOINT_SEMAPHORE(coin_selection, attempting_aps_create_tx); TRACEPOINT_SEMAPHORE(coin_selection, aps_create_tx_internal); namespace wallet { static constexpr size_t OUTPUT_GROUP_MAX_ENTRIES{100}; /** Whether the descriptor represents, directly or not, a witness program. */ static bool IsSegwit(const Descriptor& desc) { if (const auto typ = desc.GetOutputType()) return *typ != OutputType::LEGACY; return false; } /** Whether to assume ECDSA signatures' will be high-r. */ static bool UseMaxSig(const std::optional<CTxIn>& txin, const CCoinControl* coin_control) { // Use max sig if watch only inputs were used or if this particular input is an external input // to ensure a sufficient fee is attained for the requested feerate. return coin_control && txin && coin_control->IsExternalSelected(txin->prevout); } /** Get the size of an input (in witness units) once it's signed. * * @param desc The output script descriptor of the coin spent by this input. * @param txin Optionally the txin to estimate the size of. Used to determine the size of ECDSA signatures. * @param coin_control Information about the context to determine the size of ECDSA signatures. * @param tx_is_segwit Whether the transaction has at least a single input spending a segwit coin. * @param can_grind_r Whether the signer will be able to grind the R of the signature. */ static std::optional<int64_t> MaxInputWeight(const Descriptor& desc, const std::optional<CTxIn>& txin, const CCoinControl* coin_control, const bool tx_is_segwit, const bool can_grind_r) { if (const auto sat_weight = desc.MaxSatisfactionWeight(!can_grind_r || UseMaxSig(txin, coin_control))) { if (const auto elems_count = desc.MaxSatisfactionElems()) { const bool is_segwit = IsSegwit(desc); // Account for the size of the scriptsig and the number of elements on the witness stack. Note // that if any input in the transaction is spending a witness program, we need to specify the // witness stack size for every input regardless of whether it is segwit itself. // NOTE: this also works in case of mixed scriptsig-and-witness such as in p2sh-wrapped segwit v0 // outputs. In this case the size of the scriptsig length will always be one (since the redeemScript // is always a push of the witness program in this case, which is smaller than 253 bytes). const int64_t scriptsig_len = is_segwit ? 1 : GetSizeOfCompactSize(*sat_weight / WITNESS_SCALE_FACTOR); const int64_t witstack_len = is_segwit ? GetSizeOfCompactSize(*elems_count) : (tx_is_segwit ? 1 : 0); // previous txid + previous vout + sequence + scriptsig len + witstack size + scriptsig or witness // NOTE: sat_weight already accounts for the witness discount accordingly. return (32 + 4 + 4 + scriptsig_len) * WITNESS_SCALE_FACTOR + witstack_len + *sat_weight; } } return {}; } int CalculateMaximumSignedInputSize(const CTxOut& txout, const COutPoint outpoint, const SigningProvider* provider, bool can_grind_r, const CCoinControl* coin_control) { if (!provider) return -1; if (const auto desc = InferDescriptor(txout.scriptPubKey, *provider)) { if (const auto weight = MaxInputWeight(*desc, CTxIn{outpoint}, coin_control, true, can_grind_r)) { return static_cast<int>(GetVirtualTransactionSize(*weight, 0, 0)); } } return -1; } 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(), wallet->CanGrindR(), coin_control); } /** Infer a descriptor for the given output script. */ static std::unique_ptr<Descriptor> GetDescriptor(const CWallet* wallet, const CCoinControl* coin_control, const CScript script_pubkey) { MultiSigningProvider providers; for (const auto spkman: wallet->GetScriptPubKeyMans(script_pubkey)) { providers.AddProvider(spkman->GetSolvingProvider(script_pubkey)); } if (coin_control) { providers.AddProvider(std::make_unique<FlatSigningProvider>(coin_control->m_external_provider)); } return InferDescriptor(script_pubkey, providers); } /** Infer the maximum size of this input after it will be signed. */ static std::optional<int64_t> GetSignedTxinWeight(const CWallet* wallet, const CCoinControl* coin_control, const CTxIn& txin, const CTxOut& txo, const bool tx_is_segwit, const bool can_grind_r) { // If weight was provided, use that. std::optional<int64_t> weight; if (coin_control && (weight = coin_control->GetInputWeight(txin.prevout))) { return weight.value(); } // Otherwise, use the maximum satisfaction size provided by the descriptor. std::unique_ptr<Descriptor> desc{GetDescriptor(wallet, coin_control, txo.scriptPubKey)}; if (desc) return MaxInputWeight(*desc, {txin}, coin_control, tx_is_segwit, can_grind_r); return {}; } // 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) { // version + nLockTime + input count + output count int64_t weight = (4 + 4 + GetSizeOfCompactSize(tx.vin.size()) + GetSizeOfCompactSize(tx.vout.size())) * WITNESS_SCALE_FACTOR; // Whether any input spends a witness program. Necessary to run before the next loop over the // inputs in order to accurately compute the compactSize length for the witness data per input. bool is_segwit = std::any_of(txouts.begin(), txouts.end(), [&](const CTxOut& txo) { std::unique_ptr<Descriptor> desc{GetDescriptor(wallet, coin_control, txo.scriptPubKey)}; if (desc) return IsSegwit(*desc); return false; }); // Segwit marker and flag if (is_segwit) weight += 2; // Add the size of the transaction outputs. for (const auto& txo : tx.vout) weight += GetSerializeSize(txo) * WITNESS_SCALE_FACTOR; // Add the size of the transaction inputs as if they were signed. for (uint32_t i = 0; i < txouts.size(); i++) { const auto txin_weight = GetSignedTxinWeight(wallet, coin_control, tx.vin[i], txouts[i], is_segwit, wallet->CanGrindR()); if (!txin_weight) return TxSize{-1, -1}; assert(*txin_weight > -1); weight += *txin_weight; } // It's ok to use 0 as the number of sigops since we never create any pathological transaction. return TxSize{GetVirtualTransactionSize(weight, 0, 0), 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.GetTx()->vout.size()); txouts.emplace_back(mi->second.GetTx()->vout.at(input.prevout.n)); } else if (coin_control) { const auto& txout{coin_control->GetExternalOutput(input.prevout)}; if (!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(Size()); for (const auto& it : coins) { all.insert(all.end(), it.second.begin(), it.second.end()); } return all; } 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.contains(coin.outpoint)) return false; // update cached amounts total_amount -= coin.txout.nValue; if (coin.HasEffectiveValue() && total_effective_amount.has_value()) 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) { std::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<CoinsResult> FetchSelectedInputs(const CWallet& wallet, const CCoinControl& coin_control, const CoinSelectionParams& coin_selection_params) { CoinsResult result; const bool can_grind_r = wallet.CanGrindR(); std::map<COutPoint, CAmount> map_of_bump_fees = wallet.chain().calculateIndividualBumpFees(coin_control.ListSelected(), coin_selection_params.m_effective_feerate); for (const COutPoint& outpoint : coin_control.ListSelected()) { int64_t input_bytes = coin_control.GetInputWeight(outpoint).value_or(-1); if (input_bytes != -1) { input_bytes = GetVirtualTransactionSize(input_bytes, 0, 0); } CTxOut txout; if (auto txo = wallet.GetTXO(outpoint)) { txout = txo->GetTxOut(); if (input_bytes == -1) { input_bytes = CalculateMaximumSignedInputSize(txout, &wallet, &coin_control); } const CWalletTx& parent_tx = txo->GetWalletTx(); if (wallet.GetTxDepthInMainChain(parent_tx) == 0) { if (parent_tx.GetTx()->version == TRUC_VERSION && coin_control.m_version != TRUC_VERSION) { return util::Error{strprintf(_("Can't spend unconfirmed version 3 pre-selected input with a version %d tx"), coin_control.m_version)}; } else if (coin_control.m_version == TRUC_VERSION && parent_tx.GetTx()->version != TRUC_VERSION) { return util::Error{strprintf(_("Can't spend unconfirmed version %d pre-selected input with a version 3 tx"), parent_tx.GetTx()->version)}; } } } else { // The input is external. We did not find the tx in mapWallet. const auto out{coin_control.GetExternalOutput(outpoint)}; if (!out) { return util::Error{strprintf(_("Not found pre-selected input %s"), outpoint.ToString())}; } txout = *out; } if (input_bytes == -1) { input_bytes = CalculateMaximumSignedInputSize(txout, outpoint, &coin_control.m_external_provider, can_grind_r, &coin_control); } 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, 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, /*solvable=*/true, /*safe=*/true, /*time=*/0, /*from_me=*/false, coin_selection_params.m_effective_feerate); output.ApplyBumpFee(map_of_bump_fees.at(output.outpoint)); result.Add(OutputType::UNKNOWN, output); } return result; } CoinsResult AvailableCoins(const CWallet& wallet, const CCoinControl* coinControl, std::optional<CFeeRate> feerate, const CoinFilterParams& params) { AssertLockHeld(wallet.cs_wallet); CoinsResult result; // track unconfirmed truc outputs separately if we are tracking trucness std::vector<std::pair<OutputType, COutput>> unconfirmed_truc_coins; std::unordered_map<Txid, CAmount, SaltedTxidHasher> truc_txid_by_value; // 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}; const bool can_grind_r = wallet.CanGrindR(); std::vector<COutPoint> outpoints; std::set<Txid> trusted_parents; // Cache for whether each tx passes the tx level checks (first bool), and whether the transaction is "safe" (second bool) std::unordered_map<Txid, std::pair<bool, bool>, SaltedTxidHasher> tx_safe_cache; for (const auto& [outpoint, txo] : wallet.GetTXOs()) { const CWalletTx& wtx = txo.GetWalletTx(); const CTxOut& output = txo.GetTxOut(); if (tx_safe_cache.contains(outpoint.hash) && !tx_safe_cache.at(outpoint.hash).first) { continue; } int nDepth = wallet.GetTxDepthInMainChain(wtx); // Perform tx level checks if we haven't already come across outputs from this tx before. if (!tx_safe_cache.contains(outpoint.hash)) { tx_safe_cache[outpoint.hash] = {false, false}; if (wallet.IsTxImmatureCoinBase(wtx) && !params.include_immature_coinbase) continue; 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.m_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.m_replaced_by_txid) { safeTx = false; } if (nDepth == 0 && params.check_version_trucness) { if (coinControl->m_version == TRUC_VERSION) { if (wtx.GetTx()->version != TRUC_VERSION) continue; // this unconfirmed v3 transaction already has a child if (wtx.truc_child_in_mempool.has_value()) continue; // this unconfirmed v3 transaction has a parent: spending would create a third generation size_t ancestors, unused_cluster_count; wallet.chain().getTransactionAncestry(wtx.GetTx()->GetHash(), ancestors, unused_cluster_count); if (ancestors > 1) continue; } else { if (wtx.GetTx()->version == TRUC_VERSION) continue; } } if (only_safe && !safeTx) { continue; } if (nDepth < min_depth || nDepth > max_depth) { continue; } tx_safe_cache[outpoint.hash] = {true, safeTx}; } const auto& [tx_ok, tx_safe] = tx_safe_cache.at(outpoint.hash); if (!Assume(tx_ok)) { continue; } 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) && params.skip_locked) continue; if (wallet.IsSpent(outpoint)) continue; if (!allow_used_addresses && wallet.IsSpentKey(output.scriptPubKey)) { continue; } bool tx_from_me = CachedTxIsFromMe(wallet, wtx); std::unique_ptr<SigningProvider> provider = wallet.GetSolvingProvider(output.scriptPubKey); int input_bytes = CalculateMaximumSignedInputSize(output, COutPoint(), provider.get(), can_grind_r, coinControl); // Because CalculateMaximumSignedInputSize infers a solvable descriptor to get the satisfaction size, // it is safe to assume that this input is solvable if input_bytes is greater than -1. bool solvable = input_bytes > -1; // 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; } auto available_output_type = GetOutputType(type, is_from_p2sh); auto available_output = COutput(outpoint, output, nDepth, input_bytes, solvable, tx_safe, wtx.GetTxTime(), tx_from_me, feerate); if (wtx.GetTx()->version == TRUC_VERSION && nDepth == 0 && params.check_version_trucness) { unconfirmed_truc_coins.emplace_back(available_output_type, available_output); auto [it, _] = truc_txid_by_value.try_emplace(wtx.GetTx()->GetHash(), 0); it->second += output.nValue; } else { result.Add(available_output_type, available_output); } outpoints.push_back(outpoint); // 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 all the coins from one TRUC transaction, that have the highest value. // This could be improved in the future by encoding these restrictions in // the coin selection itself so that we don't have to filter out // other unconfirmed TRUC coins beforehand. if (params.check_version_trucness && unconfirmed_truc_coins.size() > 0) { auto highest_value_truc_tx = std::max_element(truc_txid_by_value.begin(), truc_txid_by_value.end(), [](const auto& tx1, const auto& tx2){ return tx1.second < tx2.second; }); const Txid& truc_txid = highest_value_truc_tx->first; for (const auto& [type, output] : unconfirmed_truc_coins) { if (output.outpoint.hash == truc_txid) { result.Add(type, output); } } } if (feerate.has_value()) { std::map<COutPoint, CAmount> map_of_bump_fees = wallet.chain().calculateIndividualBumpFees(outpoints, feerate.value()); for (auto& [_, outputs] : result.coins) { for (auto& output : outputs) { output.ApplyBumpFee(map_of_bump_fees.at(output.outpoint)); } } } return result; } const CTxOut& FindNonChangeParentOutput(const CWallet& wallet, const COutPoint& outpoint) { AssertLockHeld(wallet.cs_wallet); const CWalletTx* wtx{Assert(wallet.GetWalletTx(outpoint.hash))}; const CTransaction* ptx = wtx->GetTx().get(); int n = outpoint.n; while (OutputIsChange(wallet, ptx->vout[n]) && ptx->vin.size() > 0) { const COutPoint& prevout = ptx->vin[0].prevout; const CWalletTx* it = wallet.GetWalletTx(prevout.hash); if (!it || it->GetTx()->vout.size() <= prevout.n || !wallet.IsMine(it->GetTx()->vout[prevout.n])) { break; } ptx = it->GetTx().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; CCoinControl coin_control; CoinFilterParams coins_params; coins_params.skip_locked = false; for (const COutput& coin : AvailableCoins(wallet, &coin_control, /*feerate=*/std::nullopt, coins_params).All()) { CTxDestination address; if (!ExtractDestination(FindNonChangeParentOutput(wallet, coin.outpoint).scriptPubKey, address)) { // For backwards compatibility, we convert P2PK output scripts into PKHash destinations if (auto pk_dest = std::get_if<PubKeyDestination>(&address)) { address = PKHash(pk_dest->GetPubKey()); } else { continue; } } result[address].emplace_back(coin); } return result; } FilteredOutputGroups GroupOutputs(const CWallet& wallet, const CoinsResult& coins, const CoinSelectionParams& coin_sel_params, const std::vector<SelectionFilter>& filters, std::vector<OutputGroup>& ret_discarded_groups) { FilteredOutputGroups filtered_groups; if (!coin_sel_params.m_avoid_partial_spends) { // Allowing partial spends means no grouping. Each COutput gets its own OutputGroup for (const auto& [type, outputs] : coins.coins) { for (const COutput& output : outputs) { // Get mempool info size_t ancestors, cluster_count; wallet.chain().getTransactionAncestry(output.outpoint.hash, ancestors, cluster_count); // Create a new group per output and add it to the all groups vector OutputGroup group(coin_sel_params); group.Insert(std::make_shared<COutput>(output), ancestors, cluster_count); // Each filter maps to a different set of groups bool accepted = false; for (const auto& sel_filter : filters) { const auto& filter = sel_filter.filter; if (!group.EligibleForSpending(filter)) continue; filtered_groups[filter].Push(group, type, /*insert_positive=*/true, /*insert_mixed=*/true); accepted = true; } if (!accepted) ret_discarded_groups.emplace_back(group); } } return filtered_groups; } // 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. typedef std::map<std::pair<CScript, OutputType>, std::vector<OutputGroup>> ScriptPubKeyToOutgroup; const auto& insert_output = [&]( const std::shared_ptr<COutput>& output, OutputType type, size_t ancestors, size_t cluster_count, ScriptPubKeyToOutgroup& groups_map) { std::vector<OutputGroup>& groups = groups_map[std::make_pair(output->txout.scriptPubKey,type)]; 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(); } group->Insert(output, ancestors, cluster_count); }; ScriptPubKeyToOutgroup spk_to_groups_map; ScriptPubKeyToOutgroup spk_to_positive_groups_map; for (const auto& [type, outs] : coins.coins) { for (const COutput& output : outs) { size_t ancestors, cluster_count; wallet.chain().getTransactionAncestry(output.outpoint.hash, ancestors, cluster_count); const auto& shared_output = std::make_shared<COutput>(output); // Filter for positive only before adding the output if (output.GetEffectiveValue() > 0) { insert_output(shared_output, type, ancestors, cluster_count, spk_to_positive_groups_map); } // 'All' groups insert_output(shared_output, type, ancestors, cluster_count, spk_to_groups_map); } } // Now we go through the entire maps and pull out the OutputGroups const auto& push_output_groups = [&](const ScriptPubKeyToOutgroup& groups_map, bool positive_only) { for (const auto& [script, groups] : groups_map) { // Go through the vector backwards. This allows for the first item we deal with being the partial group. for (auto group_it = groups.rbegin(); group_it != groups.rend(); group_it++) { const OutputGroup& group = *group_it; // Each filter maps to a different set of groups bool accepted = false; for (const auto& sel_filter : filters) { const auto& filter = sel_filter.filter; if (!group.EligibleForSpending(filter)) continue; // Don't include partial groups if there are full groups too and we don't want partial groups if (group_it == groups.rbegin() && groups.size() > 1 && !filter.m_include_partial_groups) { continue; } OutputType type = script.second; // Either insert the group into the positive-only groups or the mixed ones. filtered_groups[filter].Push(group, type, positive_only, /*insert_mixed=*/!positive_only); accepted = true; } if (!accepted) ret_discarded_groups.emplace_back(group); } } }; push_output_groups(spk_to_groups_map, /*positive_only=*/ false); push_output_groups(spk_to_positive_groups_map, /*positive_only=*/ true); return filtered_groups; } FilteredOutputGroups GroupOutputs(const CWallet& wallet, const CoinsResult& coins, const CoinSelectionParams& params, const std::vector<SelectionFilter>& filters) { std::vector<OutputGroup> unused; return GroupOutputs(wallet, coins, params, filters, unused); } // Returns true if the result contains an error and the message is not empty static bool HasErrorMsg(const util::Result<SelectionResult>& res) { return !util::ErrorString(res).empty(); } util::Result<SelectionResult> AttemptSelection(interfaces::Chain& chain, const CAmount& nTargetValue, OutputGroupTypeMap& groups, 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 (auto& [type, group] : groups.groups_by_type) { auto result{ChooseSelectionResult(chain, nTargetValue, group, coin_selection_params)}; // If any specific error message appears here, then something particularly wrong happened. if (HasErrorMsg(result)) return result; // So let's return the specific error. // Append the favorable result. if (result) 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 && groups.TypesCount() > 1) { return ChooseSelectionResult(chain, nTargetValue, groups.all_groups, coin_selection_params); } // 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 util::Error(); }; util::Result<SelectionResult> ChooseSelectionResult(interfaces::Chain& chain, const CAmount& nTargetValue, Groups& groups, const CoinSelectionParams& coin_selection_params) { // Vector of results. We will choose the best one based on waste. std::vector<SelectionResult> results; std::vector<util::Result<SelectionResult>> errors; auto append_error = [&] (util::Result<SelectionResult>&& result) { // If any specific error message appears here, then something different from a simple "no selection found" happened. // Let's save it, so it can be retrieved to the user if no other selection algorithm succeeded. if (HasErrorMsg(result)) { errors.emplace_back(std::move(result)); } }; // Maximum allowed weight for selected coins. int max_transaction_weight = coin_selection_params.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT); int tx_weight_no_input = coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR; int max_selection_weight = max_transaction_weight - tx_weight_no_input; if (max_selection_weight <= 0) { return util::Error{_("Maximum transaction weight is less than transaction weight without inputs")}; } // SFFO frequently causes issues in the context of changeless input sets: skip BnB when SFFO is active if (!coin_selection_params.m_subtract_fee_outputs) { if (auto bnb_result{SelectCoinsBnB(groups.positive_group, nTargetValue, coin_selection_params.m_cost_of_change, max_selection_weight)}) { results.push_back(*bnb_result); } else append_error(std::move(bnb_result)); } // Deduct change weight because remaining Coin Selection algorithms can create change output int change_outputs_weight = coin_selection_params.change_output_size * WITNESS_SCALE_FACTOR; max_selection_weight -= change_outputs_weight; if (max_selection_weight < 0 && results.empty()) { return util::Error{_("Maximum transaction weight is too low, can not accommodate change output")}; } // 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. if (auto knapsack_result{KnapsackSolver(groups.mixed_group, nTargetValue, coin_selection_params.m_min_change_target, coin_selection_params.rng_fast, max_selection_weight)}) { results.push_back(*knapsack_result); } else append_error(std::move(knapsack_result)); if (coin_selection_params.m_effective_feerate > CFeeRate{3 * coin_selection_params.m_long_term_feerate}) { // Minimize input set for feerates of at least 3×LTFRE (default: 30 ṩ/vB+) if (auto cg_result{CoinGrinder(groups.positive_group, nTargetValue, coin_selection_params.m_min_change_target, max_selection_weight)}) { cg_result->RecalculateWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee); results.push_back(*cg_result); } else { append_error(std::move(cg_result)); } } if (auto srd_result{SelectCoinsSRD(groups.positive_group, nTargetValue, coin_selection_params.m_change_fee, coin_selection_params.rng_fast, max_selection_weight)}) { results.push_back(*srd_result); } else append_error(std::move(srd_result)); if (results.empty()) { // No solution found, retrieve the first explicit error (if any). // future: add 'severity level' to errors so the worst one can be retrieved instead of the first one. return errors.empty() ? util::Error() : std::move(errors.front()); } // If the chosen input set has unconfirmed inputs, check for synergies from overlapping ancestry for (auto& result : results) { std::vector<COutPoint> outpoints; OutputSet coins = result.GetInputSet(); CAmount summed_bump_fees = 0; for (auto& coin : coins) { if (coin->depth > 0) continue; // Bump fees only exist for unconfirmed inputs outpoints.push_back(coin->outpoint); summed_bump_fees += coin->ancestor_bump_fees; } std::optional<CAmount> combined_bump_fee = chain.calculateCombinedBumpFee(outpoints, coin_selection_params.m_effective_feerate); if (!combined_bump_fee.has_value()) { return util::Error{_("Failed to calculate bump fees, because unconfirmed UTXOs depend on an enormous cluster of unconfirmed transactions.")}; } CAmount bump_fee_overestimate = summed_bump_fees - combined_bump_fee.value(); // Avoid negative discount if mempool changed between the two bump fee snapshots. if (bump_fee_overestimate > 0) { result.SetBumpFeeDiscount(bump_fee_overestimate); } result.RecalculateWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee); } // Choose the result with the least waste // If the waste is the same, choose the one which spends more inputs. return *std::min_element(results.begin(), results.end()); } util::Result<SelectionResult> SelectCoins(const CWallet& wallet, CoinsResult& available_coins, const CoinsResult& 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.GetAppropriateTotal(coin_selection_params.m_subtract_fee_outputs).value_or(0); // 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 util::Error{_("The preselected coins total amount does not cover the transaction target. " "Please allow other inputs to be automatically selected or include more coins manually")}; } OutputSet preset_coin_set; for (const auto& output: pre_set_inputs.All()) { preset_coin_set.insert(std::make_shared<COutput>(output)); } // Return if we can cover the target only with the preset inputs if (selection_target <= 0) { SelectionResult result(nTargetValue, SelectionAlgorithm::MANUAL); result.AddInputs(preset_coin_set, coin_selection_params.m_subtract_fee_outputs); result.RecalculateWaste(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 = available_coins.GetAppropriateTotal(coin_selection_params.m_subtract_fee_outputs).value_or(0); if (selection_target > available_coins_total_amount) { return util::Error(); // Insufficient funds } // Start wallet Coin Selection procedure auto op_selection_result = AutomaticCoinSelection(wallet, available_coins, selection_target, 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()) { auto preset_total = pre_set_inputs.GetAppropriateTotal(coin_selection_params.m_subtract_fee_outputs); assert(preset_total.has_value()); SelectionResult preselected(preset_total.value(), SelectionAlgorithm::MANUAL); preselected.AddInputs(preset_coin_set, coin_selection_params.m_subtract_fee_outputs); op_selection_result->Merge(preselected); op_selection_result->RecalculateWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee); // Verify we haven't exceeded the maximum allowed weight int max_inputs_weight = coin_selection_params.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT) - (coin_selection_params.tx_noinputs_size * WITNESS_SCALE_FACTOR); if (op_selection_result->GetWeight() > max_inputs_weight) { return util::Error{_("The combination of the pre-selected inputs and the wallet automatic inputs selection exceeds the transaction maximum weight. " "Please try sending a smaller amount or manually consolidating your wallet's UTXOs")}; } } return op_selection_result; } util::Result<SelectionResult> AutomaticCoinSelection(const CWallet& wallet, CoinsResult& available_coins, const CAmount& value_to_select, const CoinSelectionParams& coin_selection_params) { // Try to enforce a mixture of cluster limits and ancestor/descendant limits on transactions we create by limiting // the ancestors and the maximum cluster count of any UTXO we use. We use the ancestor/descendant limits, which are // lower than the cluster limits, to avoid exceeding any ancestor/descendant limits of legacy nodes. This filter is safe // because a transaction's ancestor or descendant count cannot be larger than its cluster count. // TODO: these limits can be relaxed in the future, and we can replace the ancestor filter with a cluster equivalent. 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_cluster_count = (size_t)std::max<int64_t>(1, limit_descendant_count); const bool fRejectLongChains = gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS); // 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 if (coin_selection_params.m_avoid_partial_spends && available_coins.Size() > OUTPUT_GROUP_MAX_ENTRIES) { 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. { // Place coins eligibility filters on a scope increasing order. std::vector<SelectionFilter> ordered_filters{ // 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. {CoinEligibilityFilter(1, 6, 0), /*allow_mixed_output_types=*/false}, {CoinEligibilityFilter(1, 1, 0)}, }; // 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) { ordered_filters.push_back({CoinEligibilityFilter(0, 1, 2)}); ordered_filters.push_back({CoinEligibilityFilter(0, 1, std::min(size_t{4}, max_ancestors/3), std::min(size_t{4}, max_cluster_count/3))}); ordered_filters.push_back({CoinEligibilityFilter(0, 1, max_ancestors/2, max_cluster_count/2)}); // 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. ordered_filters.push_back({CoinEligibilityFilter(0, 1, max_ancestors-1, max_cluster_count-1, /*include_partial=*/true)}); // Try with unsafe inputs if they are allowed. This may spend unconfirmed outputs // received from other wallets. if (coin_selection_params.m_include_unsafe_inputs) { ordered_filters.push_back({CoinEligibilityFilter(/*conf_mine=*/0, /*conf_theirs=*/0, max_ancestors-1, max_cluster_count-1, /*include_partial=*/true)}); } // Try with unlimited ancestors/clusters. The transaction will still need to meet // local mempool policy (i.e. cluster limits) to be accepted to mempool and broadcasted, and // limits of other nodes (e.g. ancestor/descendant limits) to propagate, but OutputGroups // use heuristics that may overestimate. if (!fRejectLongChains) { ordered_filters.push_back({CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max(), std::numeric_limits<uint64_t>::max(), /*include_partial=*/true)}); } } // Group outputs and map them by coin eligibility filter std::vector<OutputGroup> discarded_groups; FilteredOutputGroups filtered_groups = GroupOutputs(wallet, available_coins, coin_selection_params, ordered_filters, discarded_groups); // Check if we still have enough balance after applying filters (some coins might be discarded) CAmount total_discarded = 0; CAmount total_unconf_long_chain = 0; for (const auto& group : discarded_groups) { total_discarded += group.GetSelectionAmount(); if (group.m_ancestors >= max_ancestors || group.m_max_cluster_count >= max_cluster_count) total_unconf_long_chain += group.GetSelectionAmount(); } if (CAmount total_amount = available_coins.GetTotalAmount() - total_discarded; total_amount < value_to_select) { // Special case, too-long-mempool cluster. if (total_amount + total_unconf_long_chain > value_to_select) { return util::Error{_("Unconfirmed UTXOs are available, but spending them creates a chain of transactions that will be rejected by the mempool")}; } return util::Error{}; // General "Insufficient Funds" } // Walk-through the filters until the solution gets found. // If no solution is found, return the first detailed error (if any). // future: add "error level" so the worst one can be picked instead. std::vector<util::Result<SelectionResult>> res_detailed_errors; CoinSelectionParams updated_selection_params = coin_selection_params; for (const auto& select_filter : ordered_filters) { auto it = filtered_groups.find(select_filter.filter); if (it == filtered_groups.end()) continue; if (updated_selection_params.m_version == TRUC_VERSION && (select_filter.filter.conf_mine == 0 || select_filter.filter.conf_theirs == 0)) { if (updated_selection_params.m_max_tx_weight > (TRUC_CHILD_MAX_WEIGHT)) { updated_selection_params.m_max_tx_weight = TRUC_CHILD_MAX_WEIGHT; } } if (auto res{AttemptSelection(wallet.chain(), value_to_select, it->second, updated_selection_params, select_filter.allow_mixed_output_types)}) { return res; // result found } else { // If any specific error message appears here, then something particularly wrong might have happened. // Save the error and continue the selection process. So if no solutions gets found, we can return // the detailed error to the upper layers. if (HasErrorMsg(res)) res_detailed_errors.emplace_back(std::move(res)); } } // Return right away if we have a detailed error if (!res_detailed_errors.empty()) return std::move(res_detailed_errors.front()); // General "Insufficient Funds" return util::Error{}; } } 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; } 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); } } uint64_t GetSerializeSizeForRecipient(const CRecipient& recipient) { return ::GetSerializeSize(CTxOut(recipient.nAmount, GetScriptForDestination(recipient.dest))); } bool IsDust(const CRecipient& recipient, const CFeeRate& dustRelayFee) { return ::IsDust(CTxOut(recipient.nAmount, GetScriptForDestination(recipient.dest)), dustRelayFee); } static util::Result<CreatedTransactionResult> CreateTransactionInternal( CWallet& wallet, const std::vector<CRecipient>& vecSend, std::optional<unsigned int> change_pos, const CCoinControl& coin_control, bool sign) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet) { AssertLockHeld(wallet.cs_wallet); FastRandomContext rng_fast; CMutableTransaction txNew; // The resulting transaction that we make txNew.version = coin_control.m_version; 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; coin_selection_params.m_include_unsafe_inputs = coin_control.m_include_unsafe_inputs; coin_selection_params.m_max_tx_weight = coin_control.m_max_tx_weight.value_or(MAX_STANDARD_TX_WEIGHT); coin_selection_params.m_version = coin_control.m_version; int minimum_tx_weight = MIN_STANDARD_TX_NONWITNESS_SIZE * WITNESS_SCALE_FACTOR; if (coin_selection_params.m_max_tx_weight.value() < minimum_tx_weight || coin_selection_params.m_max_tx_weight.value() > MAX_STANDARD_TX_WEIGHT) { return util::Error{strprintf(_("Maximum transaction weight must be between %d and %d"), minimum_tx_weight, MAX_STANDARD_TX_WEIGHT)}; } // Set the long term feerate estimate to the wallet's consolidate feerate coin_selection_params.m_long_term_feerate = wallet.m_consolidate_feerate; // 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 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) { if (IsDust(recipient, wallet.chain().relayDustFee())) { return util::Error{_("Transaction amount too small")}; } // Include the fee cost for outputs. coin_selection_params.tx_noinputs_size += GetSerializeSizeForRecipient(recipient); 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, /*coin_control=*/nullptr); // If the wallet doesn't know how to sign change output, assume p2sh-p2wpkh // as lower-bound to allow BnB to do its thing if (change_spend_size == -1) { coin_selection_params.change_spend_size = DUMMY_NESTED_P2WPKH_INPUT_SIZE; } else { coin_selection_params.change_spend_size = 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) { const auto feerate_format = FeeRateFormat::SAT_VB; auto msg{strprintf(_("Fee rate (%s) is lower than the minimum fee rate setting (%s)."), coin_control.m_feerate->ToString(feerate_format), coin_selection_params.m_effective_feerate.ToString(feerate_format))}; if (feeCalc.reason == FeeReason::REQUIRED) { msg += strprintf(_("\nConsider modifying %s (%s) or %s (%s)."), "-mintxfee", wallet.m_min_fee.ToString(feerate_format), "-minrelaytxfee", wallet.chain().relayMinFee().ToString(feerate_format)); } return util::Error{msg}; } if (feeCalc.reason == FeeReason::FALLBACK && !wallet.m_allow_fallback_fee) { // eventually allow a fallback fee return util::Error{strprintf(_("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable %s."), "-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); // 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; // This can only happen if feerate is 0, and requested destinations are value of 0 (e.g. OP_RETURN) // and no pre-selected inputs. This will result in 0-input transaction, which is consensus-invalid anyways if (selection_target == 0 && !coin_control.HasSelected()) { return util::Error{_("Transaction requires one destination of non-zero value, a non-zero feerate, or a pre-selected input")}; } // Fetch manually selected coins CoinsResult 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 auto select_coins_res = SelectCoins(wallet, available_coins, preset_inputs, /*nTargetValue=*/selection_target, coin_control, coin_selection_params); if (!select_coins_res) { // 'SelectCoins' either returns a specific error message or, if empty, means a general "Insufficient funds". const bilingual_str& err = util::ErrorString(select_coins_res); if (!err.empty()) return util::Error{err}; // Check if we have enough balance but cannot cover the fees CAmount available_balance = preset_inputs.GetTotalAmount() + available_coins.GetTotalAmount(); // Note: if SelectCoins() fails when SFFO is enabled (recipients_sum = selection_target with SFFO), // then recipients_sum > available_balance and we wouldn't enter into the if condition below. if (available_balance >= recipients_sum) { // If we have coins with balance, they should have effective values since we constructed them with valid feerate. assert(!preset_inputs.Size() || preset_inputs.GetEffectiveTotalAmount().has_value()); assert(!available_coins.Size() || available_coins.GetEffectiveTotalAmount().has_value()); CAmount available_effective_balance = preset_inputs.GetEffectiveTotalAmount().value_or(0) + available_coins.GetEffectiveTotalAmount().value_or(0); if (available_effective_balance < selection_target) { Assume(!coin_selection_params.m_subtract_fee_outputs); return util::Error{strprintf(_("The total exceeds your balance when the %s transaction fee is included."), FormatMoney(selection_target - recipients_sum))}; } } // General failure description return util::Error{_("Insufficient funds")}; } const SelectionResult& result = *select_coins_res; TRACEPOINT(coin_selection, selected_coins, wallet.GetName().c_str(), GetAlgorithmName(result.GetAlgo()).c_str(), result.GetTarget(), result.GetWaste(), result.GetSelectedValue()); // vouts to the payees txNew.vout.reserve(vecSend.size() + 1); // + 1 because of possible later insert for (const auto& recipient : vecSend) { txNew.vout.emplace_back(recipient.nAmount, GetScriptForDestination(recipient.dest)); } 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 (!change_pos) { // Insert change txn at random position: change_pos = rng_fast.randrange(txNew.vout.size() + 1); } else if ((unsigned int)*change_pos > txNew.vout.size()) { return util::Error{_("Transaction change output index out of range")}; } txNew.vout.insert(txNew.vout.begin() + *change_pos, newTxOut); } else { change_pos = std::nullopt; } // Shuffle selected coins and fill in final vin std::vector<std::shared_ptr<COutput>> selected_coins = result.GetShuffledInputVector(); if (coin_control.HasSelected() && coin_control.HasSelectedOrder()) { // When there are preselected inputs, we need to move them to be the first UTXOs // and have them be in the order selected. We can use stable_sort for this, where we // compare with the positions stored in coin_control. The COutputs that have positions // will be placed before those that don't, and those positions will be in order. std::stable_sort(selected_coins.begin(), selected_coins.end(), [&coin_control](const std::shared_ptr<COutput>& a, const std::shared_ptr<COutput>& b) { auto a_pos = coin_control.GetSelectionPos(a->outpoint); auto b_pos = coin_control.GetSelectionPos(b->outpoint); if (a_pos.has_value() && b_pos.has_value()) { return a_pos.value() < b_pos.value(); } else if (a_pos.has_value() && !b_pos.has_value()) { return true; } else { return false; } }); } // 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." bool use_anti_fee_sniping = true; const uint32_t default_sequence{coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf) ? MAX_BIP125_RBF_SEQUENCE : CTxIn::MAX_SEQUENCE_NONFINAL}; txNew.vin.reserve(selected_coins.size()); for (const auto& coin : selected_coins) { std::optional<uint32_t> sequence = coin_control.GetSequence(coin->outpoint); if (sequence) { // If an input has a preset sequence, we can't do anti-fee-sniping use_anti_fee_sniping = false; } txNew.vin.emplace_back(coin->outpoint, CScript{}, sequence.value_or(default_sequence)); auto scripts = coin_control.GetScripts(coin->outpoint); if (scripts.first) { txNew.vin.back().scriptSig = *scripts.first; } if (scripts.second) { txNew.vin.back().scriptWitness = *scripts.second; } } if (coin_control.m_locktime) { txNew.nLockTime = coin_control.m_locktime.value(); // If we have a locktime set, we can't use anti-fee-sniping use_anti_fee_sniping = false; } if (use_anti_fee_sniping) { 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) + result.GetTotalBumpFees(); 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 (change_pos && fee_needed < current_fee) { auto& change = txNew.vout.at(*change_pos); 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; unsigned int i = 0; bool fFirst = true; for (const auto& recipient : vecSend) { if (change_pos && i == *change_pos) { ++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() && change_pos) { 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 auto result = wallet.chain().checkChainLimits(tx); if (!result) { return util::Error{util::ErrorString(result)}; } } // Before we return success, we assume any change key will be used to prevent // accidental reuse. reservedest.KeepDestination(); wallet.WalletLogPrintf("Coin Selection: Algorithm:%s, Waste Metric Score:%d\n", GetAlgorithmName(result.GetAlgo()), result.GetWaste()); 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, change_pos, feeCalc); } util::Result<CreatedTransactionResult> CreateTransaction( CWallet& wallet, const std::vector<CRecipient>& vecSend, std::optional<unsigned 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); TRACEPOINT(coin_selection, normal_create_tx_internal, wallet.GetName().c_str(), bool(res), res ? res->fee : 0, res && res->change_pos.has_value() ? int32_t(*res->change_pos) : -1); 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) { TRACEPOINT(coin_selection, attempting_aps_create_tx, wallet.GetName().c_str()); CCoinControl tmp_cc = coin_control; tmp_cc.m_avoid_partial_spends = true; // Reuse the change destination from the first creation attempt to avoid skipping BIP44 indexes if (txr_ungrouped.change_pos) { ExtractDestination(txr_ungrouped.tx->vout[*txr_ungrouped.change_pos].scriptPubKey, tmp_cc.destChange); } 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}; TRACEPOINT(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.has_value() ? int32_t(*txr_grouped->change_pos) : -1); 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; } util::Result<CreatedTransactionResult> FundTransaction(CWallet& wallet, const CMutableTransaction& tx, const std::vector<CRecipient>& vecSend, std::optional<unsigned int> change_pos, bool lockUnspents, CCoinControl coinControl) { // We want to make sure tx.vout is not used now that we are passing outputs as a vector of recipients. // This sets us up to remove tx completely in a future PR in favor of passing the inputs directly. assert(tx.vout.empty()); // Set the user desired locktime coinControl.m_locktime = tx.nLockTime; // Set the user desired version coinControl.m_version = tx.version; // 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; PreselectedInput& preset_txin = coinControl.Select(outPoint); if (!wallet.IsMine(outPoint)) { if (coins[outPoint].out.IsNull()) { return util::Error{_("Unable to find UTXO for external input")}; } // The input was not in the wallet, but is in the UTXO set, so select as external preset_txin.SetTxOut(coins[outPoint].out); } preset_txin.SetSequence(txin.nSequence); preset_txin.SetScriptSig(txin.scriptSig); preset_txin.SetScriptWitness(txin.scriptWitness); } auto res = CreateTransaction(wallet, vecSend, change_pos, coinControl, false); if (!res) { return res; } if (lockUnspents) { for (const CTxIn& txin : res->tx->vin) { wallet.LockCoin(txin.prevout, /*persist=*/false); } } return res; } } // namespace wallet