269 lines
12 KiB
C++
269 lines
12 KiB
C++
// Copyright (c) 2017 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <consensus/validation.h>
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#include <wallet/coincontrol.h>
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#include <wallet/feebumper.h>
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#include <wallet/fees.h>
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#include <wallet/wallet.h>
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#include <policy/fees.h>
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#include <policy/policy.h>
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#include <policy/rbf.h>
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#include <validation.h> //for mempool access
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#include <txmempool.h>
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#include <utilmoneystr.h>
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#include <util.h>
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#include <net.h>
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//! Check whether transaction has descendant in wallet or mempool, or has been
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//! mined, or conflicts with a mined transaction. Return a feebumper::Result.
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static feebumper::Result PreconditionChecks(const CWallet* wallet, const CWalletTx& wtx, std::vector<std::string>& errors)
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{
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if (wallet->HasWalletSpend(wtx.GetHash())) {
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errors.push_back("Transaction has descendants in the wallet");
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return feebumper::Result::INVALID_PARAMETER;
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}
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{
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LOCK(mempool.cs);
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auto it_mp = mempool.mapTx.find(wtx.GetHash());
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if (it_mp != mempool.mapTx.end() && it_mp->GetCountWithDescendants() > 1) {
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errors.push_back("Transaction has descendants in the mempool");
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return feebumper::Result::INVALID_PARAMETER;
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}
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}
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if (wtx.GetDepthInMainChain() != 0) {
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errors.push_back("Transaction has been mined, or is conflicted with a mined transaction");
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return feebumper::Result::WALLET_ERROR;
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}
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if (!SignalsOptInRBF(*wtx.tx)) {
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errors.push_back("Transaction is not BIP 125 replaceable");
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return feebumper::Result::WALLET_ERROR;
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}
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if (wtx.mapValue.count("replaced_by_txid")) {
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errors.push_back(strprintf("Cannot bump transaction %s which was already bumped by transaction %s", wtx.GetHash().ToString(), wtx.mapValue.at("replaced_by_txid")));
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return feebumper::Result::WALLET_ERROR;
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}
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// check that original tx consists entirely of our inputs
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// 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)
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if (!wallet->IsAllFromMe(*wtx.tx, ISMINE_SPENDABLE)) {
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errors.push_back("Transaction contains inputs that don't belong to this wallet");
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return feebumper::Result::WALLET_ERROR;
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}
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return feebumper::Result::OK;
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}
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namespace feebumper {
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bool TransactionCanBeBumped(const CWallet* wallet, const uint256& txid)
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{
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LOCK2(cs_main, wallet->cs_wallet);
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const CWalletTx* wtx = wallet->GetWalletTx(txid);
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if (wtx == nullptr) return false;
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std::vector<std::string> errors_dummy;
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feebumper::Result res = PreconditionChecks(wallet, *wtx, errors_dummy);
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return res == feebumper::Result::OK;
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}
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Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoinControl& coin_control, CAmount total_fee, std::vector<std::string>& errors,
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CAmount& old_fee, CAmount& new_fee, CMutableTransaction& mtx)
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{
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LOCK2(cs_main, wallet->cs_wallet);
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errors.clear();
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auto it = wallet->mapWallet.find(txid);
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if (it == wallet->mapWallet.end()) {
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errors.push_back("Invalid or non-wallet transaction id");
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return Result::INVALID_ADDRESS_OR_KEY;
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}
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const CWalletTx& wtx = it->second;
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Result result = PreconditionChecks(wallet, wtx, errors);
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if (result != Result::OK) {
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return result;
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}
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// figure out which output was change
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// if there was no change output or multiple change outputs, fail
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int nOutput = -1;
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for (size_t i = 0; i < wtx.tx->vout.size(); ++i) {
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if (wallet->IsChange(wtx.tx->vout[i])) {
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if (nOutput != -1) {
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errors.push_back("Transaction has multiple change outputs");
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return Result::WALLET_ERROR;
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}
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nOutput = i;
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}
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}
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if (nOutput == -1) {
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errors.push_back("Transaction does not have a change output");
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return Result::WALLET_ERROR;
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}
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// Calculate the expected size of the new transaction.
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int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
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const int64_t maxNewTxSize = CalculateMaximumSignedTxSize(*wtx.tx, wallet);
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if (maxNewTxSize < 0) {
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errors.push_back("Transaction contains inputs that cannot be signed");
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return Result::INVALID_ADDRESS_OR_KEY;
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}
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// calculate the old fee and fee-rate
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old_fee = wtx.GetDebit(ISMINE_SPENDABLE) - wtx.tx->GetValueOut();
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CFeeRate nOldFeeRate(old_fee, txSize);
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CFeeRate nNewFeeRate;
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// The wallet uses a conservative WALLET_INCREMENTAL_RELAY_FEE value to
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// future proof against changes to network wide policy for incremental relay
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// fee that our node may not be aware of.
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CFeeRate walletIncrementalRelayFee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);
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if (::incrementalRelayFee > walletIncrementalRelayFee) {
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walletIncrementalRelayFee = ::incrementalRelayFee;
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}
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if (total_fee > 0) {
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CAmount minTotalFee = nOldFeeRate.GetFee(maxNewTxSize) + ::incrementalRelayFee.GetFee(maxNewTxSize);
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if (total_fee < minTotalFee) {
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errors.push_back(strprintf("Insufficient totalFee, must be at least %s (oldFee %s + incrementalFee %s)",
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FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxNewTxSize)), FormatMoney(::incrementalRelayFee.GetFee(maxNewTxSize))));
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return Result::INVALID_PARAMETER;
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}
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CAmount requiredFee = GetRequiredFee(maxNewTxSize);
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if (total_fee < requiredFee) {
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errors.push_back(strprintf("Insufficient totalFee (cannot be less than required fee %s)",
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FormatMoney(requiredFee)));
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return Result::INVALID_PARAMETER;
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}
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new_fee = total_fee;
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nNewFeeRate = CFeeRate(total_fee, maxNewTxSize);
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} else {
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new_fee = GetMinimumFee(maxNewTxSize, coin_control, mempool, ::feeEstimator, nullptr /* FeeCalculation */);
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nNewFeeRate = CFeeRate(new_fee, maxNewTxSize);
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// New fee rate must be at least old rate + minimum incremental relay rate
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// walletIncrementalRelayFee.GetFeePerK() should be exact, because it's initialized
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// in that unit (fee per kb).
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// However, nOldFeeRate is a calculated value from the tx fee/size, so
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// add 1 satoshi to the result, because it may have been rounded down.
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if (nNewFeeRate.GetFeePerK() < nOldFeeRate.GetFeePerK() + 1 + walletIncrementalRelayFee.GetFeePerK()) {
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nNewFeeRate = CFeeRate(nOldFeeRate.GetFeePerK() + 1 + walletIncrementalRelayFee.GetFeePerK());
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new_fee = nNewFeeRate.GetFee(maxNewTxSize);
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}
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}
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// Check that in all cases the new fee doesn't violate maxTxFee
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if (new_fee > maxTxFee) {
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errors.push_back(strprintf("Specified or calculated fee %s is too high (cannot be higher than maxTxFee %s)",
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FormatMoney(new_fee), FormatMoney(maxTxFee)));
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return Result::WALLET_ERROR;
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}
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// check that fee rate is higher than mempool's minimum fee
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// (no point in bumping fee if we know that the new tx won't be accepted to the mempool)
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// This may occur if the user set TotalFee or paytxfee too low, if fallbackfee is too low, or, perhaps,
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// in a rare situation where the mempool minimum fee increased significantly since the fee estimation just a
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// moment earlier. In this case, we report an error to the user, who may use total_fee to make an adjustment.
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CFeeRate minMempoolFeeRate = mempool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000);
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if (nNewFeeRate.GetFeePerK() < minMempoolFeeRate.GetFeePerK()) {
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errors.push_back(strprintf(
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"New fee rate (%s) is lower than the minimum fee rate (%s) to get into the mempool -- "
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"the totalFee value should be at least %s or the settxfee value should be at least %s to add transaction",
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FormatMoney(nNewFeeRate.GetFeePerK()),
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FormatMoney(minMempoolFeeRate.GetFeePerK()),
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FormatMoney(minMempoolFeeRate.GetFee(maxNewTxSize)),
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FormatMoney(minMempoolFeeRate.GetFeePerK())));
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return Result::WALLET_ERROR;
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}
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// Now modify the output to increase the fee.
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// If the output is not large enough to pay the fee, fail.
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CAmount nDelta = new_fee - old_fee;
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assert(nDelta > 0);
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mtx = *wtx.tx;
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CTxOut* poutput = &(mtx.vout[nOutput]);
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if (poutput->nValue < nDelta) {
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errors.push_back("Change output is too small to bump the fee");
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return Result::WALLET_ERROR;
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}
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// If the output would become dust, discard it (converting the dust to fee)
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poutput->nValue -= nDelta;
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if (poutput->nValue <= GetDustThreshold(*poutput, GetDiscardRate(::feeEstimator))) {
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LogPrint(BCLog::RPC, "Bumping fee and discarding dust output\n");
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new_fee += poutput->nValue;
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mtx.vout.erase(mtx.vout.begin() + nOutput);
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}
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// Mark new tx not replaceable, if requested.
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if (!coin_control.signalRbf) {
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for (auto& input : mtx.vin) {
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if (input.nSequence < 0xfffffffe) input.nSequence = 0xfffffffe;
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}
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}
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return Result::OK;
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}
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bool SignTransaction(CWallet* wallet, CMutableTransaction& mtx) {
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LOCK2(cs_main, wallet->cs_wallet);
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return wallet->SignTransaction(mtx);
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}
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Result CommitTransaction(CWallet* wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<std::string>& errors, uint256& bumped_txid)
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{
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LOCK2(cs_main, wallet->cs_wallet);
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if (!errors.empty()) {
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return Result::MISC_ERROR;
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}
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auto it = txid.IsNull() ? wallet->mapWallet.end() : wallet->mapWallet.find(txid);
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if (it == wallet->mapWallet.end()) {
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errors.push_back("Invalid or non-wallet transaction id");
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return Result::MISC_ERROR;
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}
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CWalletTx& oldWtx = it->second;
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// make sure the transaction still has no descendants and hasn't been mined in the meantime
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Result result = PreconditionChecks(wallet, oldWtx, errors);
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if (result != Result::OK) {
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return result;
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}
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// commit/broadcast the tx
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CTransactionRef tx = MakeTransactionRef(std::move(mtx));
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mapValue_t mapValue = oldWtx.mapValue;
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mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
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CReserveKey reservekey(wallet);
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CValidationState state;
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if (!wallet->CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm, oldWtx.strFromAccount, reservekey, g_connman.get(), state)) {
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// NOTE: CommitTransaction never returns false, so this should never happen.
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errors.push_back(strprintf("The transaction was rejected: %s", FormatStateMessage(state)));
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return Result::WALLET_ERROR;
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}
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bumped_txid = tx->GetHash();
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if (state.IsInvalid()) {
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// This can happen if the mempool rejected the transaction. Report
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// what happened in the "errors" response.
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errors.push_back(strprintf("Error: The transaction was rejected: %s", FormatStateMessage(state)));
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}
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// mark the original tx as bumped
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if (!wallet->MarkReplaced(oldWtx.GetHash(), bumped_txid)) {
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// TODO: see if JSON-RPC has a standard way of returning a response
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// along with an exception. It would be good to return information about
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// wtxBumped to the caller even if marking the original transaction
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// replaced does not succeed for some reason.
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errors.push_back("Created new bumpfee transaction but could not mark the original transaction as replaced");
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}
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return Result::OK;
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}
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} // namespace feebumper
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