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// Copyright (c) 2017-2021 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 <interfaces/chain.h>
#include <policy/fees.h>
#include <policy/policy.h>
#include <util/moneystr.h>
#include <util/rbf.h>
#include <util/system.h>
#include <util/translation.h>
#include <wallet/coincontrol.h>
#include <wallet/feebumper.h>
#include <wallet/fees.h>
#include <wallet/receive.h>
#include <wallet/spend.h>
#include <wallet/wallet.h>
namespace wallet {
//! Check whether transaction has descendant in wallet or mempool, or has been
//! mined, or conflicts with a mined transaction. Return a feebumper::Result.
static feebumper::Result PreconditionChecks(const CWallet& wallet, const CWalletTx& wtx, std::vector<bilingual_str>& errors) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
{
if (wallet.HasWalletSpend(wtx.tx)) {
errors.push_back(Untranslated("Transaction has descendants in the wallet"));
return feebumper::Result::INVALID_PARAMETER;
}
{
if (wallet.chain().hasDescendantsInMempool(wtx.GetHash())) {
errors.push_back(Untranslated("Transaction has descendants in the mempool"));
return feebumper::Result::INVALID_PARAMETER;
}
}
if (wallet.GetTxDepthInMainChain(wtx) != 0) {
errors.push_back(Untranslated("Transaction has been mined, or is conflicted with a mined transaction"));
return feebumper::Result::WALLET_ERROR;
}
if (!SignalsOptInRBF(*wtx.tx)) {
errors.push_back(Untranslated("Transaction is not BIP 125 replaceable"));
return feebumper::Result::WALLET_ERROR;
}
if (wtx.mapValue.count("replaced_by_txid")) {
errors.push_back(strprintf(Untranslated("Cannot bump transaction %s which was already bumped by transaction %s"), wtx.GetHash().ToString(), wtx.mapValue.at("replaced_by_txid")));
return feebumper::Result::WALLET_ERROR;
}
// check that original tx consists entirely of our inputs
// if not, we can't bump the fee, because the wallet has no way of knowing the value of the other inputs (thus the fee)
isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
if (!AllInputsMine(wallet, *wtx.tx, filter)) {
errors.push_back(Untranslated("Transaction contains inputs that don't belong to this wallet"));
return feebumper::Result::WALLET_ERROR;
}
return feebumper::Result::OK;
}
//! Check if the user provided a valid feeRate
static feebumper::Result CheckFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CFeeRate& newFeerate, const int64_t maxTxSize, std::vector<bilingual_str>& errors)
{
// check that fee rate is higher than mempool's minimum fee
// (no point in bumping fee if we know that the new tx won't be accepted to the mempool)
// This may occur if the user set fee_rate or paytxfee too low, if fallbackfee is too low, or, perhaps,
// in a rare situation where the mempool minimum fee increased significantly since the fee estimation just a
// moment earlier. In this case, we report an error to the user, who may adjust the fee.
CFeeRate minMempoolFeeRate = wallet.chain().mempoolMinFee();
if (newFeerate.GetFeePerK() < minMempoolFeeRate.GetFeePerK()) {
errors.push_back(strprintf(
Untranslated("New fee rate (%s) is lower than the minimum fee rate (%s) to get into the mempool -- "),
FormatMoney(newFeerate.GetFeePerK()),
FormatMoney(minMempoolFeeRate.GetFeePerK())));
return feebumper::Result::WALLET_ERROR;
}
CAmount new_total_fee = newFeerate.GetFee(maxTxSize);
CFeeRate incrementalRelayFee = std::max(wallet.chain().relayIncrementalFee(), CFeeRate(WALLET_INCREMENTAL_RELAY_FEE));
// Given old total fee and transaction size, calculate the old feeRate
isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
CAmount old_fee = CachedTxGetDebit(wallet, wtx, filter) - wtx.tx->GetValueOut();
const int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
CFeeRate nOldFeeRate(old_fee, txSize);
// Min total fee is old fee + relay fee
CAmount minTotalFee = nOldFeeRate.GetFee(maxTxSize) + incrementalRelayFee.GetFee(maxTxSize);
if (new_total_fee < minTotalFee) {
errors.push_back(strprintf(Untranslated("Insufficient total fee %s, must be at least %s (oldFee %s + incrementalFee %s)"),
FormatMoney(new_total_fee), FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxTxSize)), FormatMoney(incrementalRelayFee.GetFee(maxTxSize))));
return feebumper::Result::INVALID_PARAMETER;
}
CAmount requiredFee = GetRequiredFee(wallet, maxTxSize);
if (new_total_fee < requiredFee) {
errors.push_back(strprintf(Untranslated("Insufficient total fee (cannot be less than required fee %s)"),
FormatMoney(requiredFee)));
return feebumper::Result::INVALID_PARAMETER;
}
// Check that in all cases the new fee doesn't violate maxTxFee
const CAmount max_tx_fee = wallet.m_default_max_tx_fee;
if (new_total_fee > max_tx_fee) {
errors.push_back(strprintf(Untranslated("Specified or calculated fee %s is too high (cannot be higher than -maxtxfee %s)"),
FormatMoney(new_total_fee), FormatMoney(max_tx_fee)));
return feebumper::Result::WALLET_ERROR;
}
return feebumper::Result::OK;
}
static CFeeRate EstimateFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CAmount old_fee, const CCoinControl& coin_control)
{
// Get the fee rate of the original transaction. This is calculated from
// the tx fee/vsize, so it may have been rounded down. Add 1 satoshi to the
// result.
int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
CFeeRate feerate(old_fee, txSize);
feerate += CFeeRate(1);
// The node has a configurable incremental relay fee. Increment the fee by
// the minimum of that and the wallet's conservative
// WALLET_INCREMENTAL_RELAY_FEE value to future proof against changes to
// network wide policy for incremental relay fee that our node may not be
// aware of. This ensures we're over the required relay fee rate
// (BIP 125 rule 4). The replacement tx will be at least as large as the
// original tx, so the total fee will be greater (BIP 125 rule 3)
CFeeRate node_incremental_relay_fee = wallet.chain().relayIncrementalFee();
CFeeRate wallet_incremental_relay_fee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);
feerate += std::max(node_incremental_relay_fee, wallet_incremental_relay_fee);
// Fee rate must also be at least the wallet's GetMinimumFeeRate
CFeeRate min_feerate(GetMinimumFeeRate(wallet, coin_control, /*feeCalc=*/nullptr));
// Set the required fee rate for the replacement transaction in coin control.
return std::max(feerate, min_feerate);
}
namespace feebumper {
bool TransactionCanBeBumped(const CWallet& wallet, const uint256& txid)
{
LOCK(wallet.cs_wallet);
const CWalletTx* wtx = wallet.GetWalletTx(txid);
if (wtx == nullptr) return false;
std::vector<bilingual_str> errors_dummy;
feebumper::Result res = PreconditionChecks(wallet, *wtx, errors_dummy);
return res == feebumper::Result::OK;
}
Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCoinControl& coin_control, std::vector<bilingual_str>& errors,
CAmount& old_fee, CAmount& new_fee, CMutableTransaction& mtx)
{
// We are going to modify coin control later, copy to re-use
CCoinControl new_coin_control(coin_control);
LOCK(wallet.cs_wallet);
errors.clear();
auto it = wallet.mapWallet.find(txid);
if (it == wallet.mapWallet.end()) {
errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
return Result::INVALID_ADDRESS_OR_KEY;
}
const CWalletTx& wtx = it->second;
Result result = PreconditionChecks(wallet, wtx, errors);
if (result != Result::OK) {
return result;
}
// Fill in recipients(and preserve a single change key if there is one)
std::vector<CRecipient> recipients;
for (const auto& output : wtx.tx->vout) {
if (!OutputIsChange(wallet, output)) {
CRecipient recipient = {output.scriptPubKey, output.nValue, false};
recipients.push_back(recipient);
} else {
CTxDestination change_dest;
ExtractDestination(output.scriptPubKey, change_dest);
new_coin_control.destChange = change_dest;
}
}
isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
old_fee = CachedTxGetDebit(wallet, wtx, filter) - wtx.tx->GetValueOut();
if (coin_control.m_feerate) {
// The user provided a feeRate argument.
// We calculate this here to avoid compiler warning on the cs_wallet lock
const int64_t maxTxSize{CalculateMaximumSignedTxSize(*wtx.tx, &wallet).vsize};
Result res = CheckFeeRate(wallet, wtx, *new_coin_control.m_feerate, maxTxSize, errors);
if (res != Result::OK) {
return res;
}
} else {
// The user did not provide a feeRate argument
new_coin_control.m_feerate = EstimateFeeRate(wallet, wtx, old_fee, new_coin_control);
}
// Fill in required inputs we are double-spending(all of them)
// N.B.: bip125 doesn't require all the inputs in the replaced transaction to be
// used in the replacement transaction, but it's very important for wallets to make
// sure that happens. If not, it would be possible to bump a transaction A twice to
// A2 and A3 where A2 and A3 don't conflict (or alternatively bump A to A2 and A2
// to A3 where A and A3 don't conflict). If both later get confirmed then the sender
// has accidentally double paid.
for (const auto& inputs : wtx.tx->vin) {
new_coin_control.Select(COutPoint(inputs.prevout));
}
new_coin_control.m_allow_other_inputs = true;
// We cannot source new unconfirmed inputs(bip125 rule 2)
new_coin_control.m_min_depth = 1;
constexpr int RANDOM_CHANGE_POSITION = -1;
auto res = CreateTransaction(wallet, recipients, RANDOM_CHANGE_POSITION, new_coin_control, false);
if (!res) {
errors.push_back(Untranslated("Unable to create transaction.") + Untranslated(" ") + res.GetError());
return Result::WALLET_ERROR;
}
const auto& txr = res.GetObj();
// Write back new fee if successful
new_fee = txr.fee;
// Write back transaction
mtx = CMutableTransaction(*txr.tx);
return Result::OK;
}
bool SignTransaction(CWallet& wallet, CMutableTransaction& mtx) {
LOCK(wallet.cs_wallet);
return wallet.SignTransaction(mtx);
}
Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<bilingual_str>& errors, uint256& bumped_txid)
{
LOCK(wallet.cs_wallet);
if (!errors.empty()) {
return Result::MISC_ERROR;
}
auto it = txid.IsNull() ? wallet.mapWallet.end() : wallet.mapWallet.find(txid);
if (it == wallet.mapWallet.end()) {
errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
return Result::MISC_ERROR;
}
const CWalletTx& oldWtx = it->second;
// make sure the transaction still has no descendants and hasn't been mined in the meantime
Result result = PreconditionChecks(wallet, oldWtx, errors);
if (result != Result::OK) {
return result;
}
// commit/broadcast the tx
CTransactionRef tx = MakeTransactionRef(std::move(mtx));
mapValue_t mapValue = oldWtx.mapValue;
mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
wallet.CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm);
// mark the original tx as bumped
bumped_txid = tx->GetHash();
if (!wallet.MarkReplaced(oldWtx.GetHash(), bumped_txid)) {
errors.push_back(Untranslated("Created new bumpfee transaction but could not mark the original transaction as replaced"));
}
return Result::OK;
}
} // namespace feebumper
} // namespace wallet
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