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Diffstat (limited to 'src/wallet/feebumper.cpp')
-rw-r--r-- | src/wallet/feebumper.cpp | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp new file mode 100644 index 0000000000..c10a9eccd9 --- /dev/null +++ b/src/wallet/feebumper.cpp @@ -0,0 +1,296 @@ +// Copyright (c) 2017 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "consensus/validation.h" +#include "wallet/feebumper.h" +#include "wallet/wallet.h" +#include "policy/fees.h" +#include "policy/policy.h" +#include "policy/rbf.h" +#include "validation.h" //for mempool access +#include "txmempool.h" +#include "utilmoneystr.h" +#include "util.h" +#include "net.h" + +// Calculate the size of the transaction assuming all signatures are max size +// Use DummySignatureCreator, which inserts 72 byte signatures everywhere. +// TODO: re-use this in CWallet::CreateTransaction (right now +// CreateTransaction uses the constructed dummy-signed tx to do a priority +// calculation, but we should be able to refactor after priority is removed). +// NOTE: this requires that all inputs must be in mapWallet (eg the tx should +// be IsAllFromMe). +int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *pWallet) +{ + CMutableTransaction txNew(tx); + std::vector<CInputCoin> vCoins; + // Look up the inputs. We should have already checked that this transaction + // IsAllFromMe(ISMINE_SPENDABLE), so every input should already be in our + // wallet, with a valid index into the vout array. + for (auto& input : tx.vin) { + const auto mi = pWallet->mapWallet.find(input.prevout.hash); + assert(mi != pWallet->mapWallet.end() && input.prevout.n < mi->second.tx->vout.size()); + vCoins.emplace_back(CInputCoin(&(mi->second), input.prevout.n)); + } + if (!pWallet->DummySignTx(txNew, vCoins)) { + // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE) + // implies that we can sign for every input. + return -1; + } + return GetVirtualTransactionSize(txNew); +} + +bool CFeeBumper::preconditionChecks(const CWallet *pWallet, const CWalletTx& wtx) { + if (pWallet->HasWalletSpend(wtx.GetHash())) { + vErrors.push_back("Transaction has descendants in the wallet"); + currentResult = BumpFeeResult::INVALID_PARAMETER; + return false; + } + + { + LOCK(mempool.cs); + auto it_mp = mempool.mapTx.find(wtx.GetHash()); + if (it_mp != mempool.mapTx.end() && it_mp->GetCountWithDescendants() > 1) { + vErrors.push_back("Transaction has descendants in the mempool"); + currentResult = BumpFeeResult::INVALID_PARAMETER; + return false; + } + } + + if (wtx.GetDepthInMainChain() != 0) { + vErrors.push_back("Transaction has been mined, or is conflicted with a mined transaction"); + currentResult = BumpFeeResult::WALLET_ERROR; + return false; + } + return true; +} + +CFeeBumper::CFeeBumper(const CWallet *pWallet, const uint256 txidIn, int newConfirmTarget, bool specifiedConfirmTarget, CAmount totalFee, bool newTxReplaceable) + : + txid(std::move(txidIn)), + nOldFee(0), + nNewFee(0) +{ + vErrors.clear(); + bumpedTxid.SetNull(); + AssertLockHeld(pWallet->cs_wallet); + if (!pWallet->mapWallet.count(txid)) { + vErrors.push_back("Invalid or non-wallet transaction id"); + currentResult = BumpFeeResult::INVALID_ADDRESS_OR_KEY; + return; + } + auto it = pWallet->mapWallet.find(txid); + const CWalletTx& wtx = it->second; + + if (!preconditionChecks(pWallet, wtx)) { + return; + } + + if (!SignalsOptInRBF(wtx)) { + vErrors.push_back("Transaction is not BIP 125 replaceable"); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + if (wtx.mapValue.count("replaced_by_txid")) { + vErrors.push_back(strprintf("Cannot bump transaction %s which was already bumped by transaction %s", txid.ToString(), wtx.mapValue.at("replaced_by_txid"))); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // 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) + if (!pWallet->IsAllFromMe(wtx, ISMINE_SPENDABLE)) { + vErrors.push_back("Transaction contains inputs that don't belong to this wallet"); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // figure out which output was change + // if there was no change output or multiple change outputs, fail + int nOutput = -1; + for (size_t i = 0; i < wtx.tx->vout.size(); ++i) { + if (pWallet->IsChange(wtx.tx->vout[i])) { + if (nOutput != -1) { + vErrors.push_back("Transaction has multiple change outputs"); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + nOutput = i; + } + } + if (nOutput == -1) { + vErrors.push_back("Transaction does not have a change output"); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // Calculate the expected size of the new transaction. + int64_t txSize = GetVirtualTransactionSize(*(wtx.tx)); + const int64_t maxNewTxSize = CalculateMaximumSignedTxSize(*wtx.tx, pWallet); + if (maxNewTxSize < 0) { + vErrors.push_back("Transaction contains inputs that cannot be signed"); + currentResult = BumpFeeResult::INVALID_ADDRESS_OR_KEY; + return; + } + + // calculate the old fee and fee-rate + nOldFee = wtx.GetDebit(ISMINE_SPENDABLE) - wtx.tx->GetValueOut(); + CFeeRate nOldFeeRate(nOldFee, txSize); + CFeeRate nNewFeeRate; + // The wallet uses a 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. + CFeeRate walletIncrementalRelayFee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE); + if (::incrementalRelayFee > walletIncrementalRelayFee) { + walletIncrementalRelayFee = ::incrementalRelayFee; + } + + if (totalFee > 0) { + CAmount minTotalFee = nOldFeeRate.GetFee(maxNewTxSize) + ::incrementalRelayFee.GetFee(maxNewTxSize); + if (totalFee < minTotalFee) { + vErrors.push_back(strprintf("Insufficient totalFee, must be at least %s (oldFee %s + incrementalFee %s)", + FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxNewTxSize)), FormatMoney(::incrementalRelayFee.GetFee(maxNewTxSize)))); + currentResult = BumpFeeResult::INVALID_PARAMETER; + return; + } + CAmount requiredFee = CWallet::GetRequiredFee(maxNewTxSize); + if (totalFee < requiredFee) { + vErrors.push_back(strprintf("Insufficient totalFee (cannot be less than required fee %s)", + FormatMoney(requiredFee))); + currentResult = BumpFeeResult::INVALID_PARAMETER; + return; + } + nNewFee = totalFee; + nNewFeeRate = CFeeRate(totalFee, maxNewTxSize); + } else { + // if user specified a confirm target then don't consider any global payTxFee + if (specifiedConfirmTarget) { + nNewFee = CWallet::GetMinimumFee(maxNewTxSize, newConfirmTarget, mempool, ::feeEstimator, true); + } + // otherwise use the regular wallet logic to select payTxFee or default confirm target + else { + nNewFee = CWallet::GetMinimumFee(maxNewTxSize, newConfirmTarget, mempool, ::feeEstimator); + } + + nNewFeeRate = CFeeRate(nNewFee, maxNewTxSize); + + // New fee rate must be at least old rate + minimum incremental relay rate + // walletIncrementalRelayFee.GetFeePerK() should be exact, because it's initialized + // in that unit (fee per kb). + // However, nOldFeeRate is a calculated value from the tx fee/size, so + // add 1 satoshi to the result, because it may have been rounded down. + if (nNewFeeRate.GetFeePerK() < nOldFeeRate.GetFeePerK() + 1 + walletIncrementalRelayFee.GetFeePerK()) { + nNewFeeRate = CFeeRate(nOldFeeRate.GetFeePerK() + 1 + walletIncrementalRelayFee.GetFeePerK()); + nNewFee = nNewFeeRate.GetFee(maxNewTxSize); + } + } + + // Check that in all cases the new fee doesn't violate maxTxFee + if (nNewFee > maxTxFee) { + vErrors.push_back(strprintf("Specified or calculated fee %s is too high (cannot be higher than maxTxFee %s)", + FormatMoney(nNewFee), FormatMoney(maxTxFee))); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // 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 TotalFee 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 use totalFee to make an adjustment. + CFeeRate minMempoolFeeRate = mempool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000); + if (nNewFeeRate.GetFeePerK() < minMempoolFeeRate.GetFeePerK()) { + vErrors.push_back(strprintf("New fee rate (%s) is less than the minimum fee rate (%s) to get into the mempool. totalFee value should to be at least %s or settxfee value should be at least %s to add transaction.", FormatMoney(nNewFeeRate.GetFeePerK()), FormatMoney(minMempoolFeeRate.GetFeePerK()), FormatMoney(minMempoolFeeRate.GetFee(maxNewTxSize)), FormatMoney(minMempoolFeeRate.GetFeePerK()))); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // Now modify the output to increase the fee. + // If the output is not large enough to pay the fee, fail. + CAmount nDelta = nNewFee - nOldFee; + assert(nDelta > 0); + mtx = *wtx.tx; + CTxOut* poutput = &(mtx.vout[nOutput]); + if (poutput->nValue < nDelta) { + vErrors.push_back("Change output is too small to bump the fee"); + currentResult = BumpFeeResult::WALLET_ERROR; + return; + } + + // If the output would become dust, discard it (converting the dust to fee) + poutput->nValue -= nDelta; + if (poutput->nValue <= GetDustThreshold(*poutput, ::dustRelayFee)) { + LogPrint(BCLog::RPC, "Bumping fee and discarding dust output\n"); + nNewFee += poutput->nValue; + mtx.vout.erase(mtx.vout.begin() + nOutput); + } + + // Mark new tx not replaceable, if requested. + if (!newTxReplaceable) { + for (auto& input : mtx.vin) { + if (input.nSequence < 0xfffffffe) input.nSequence = 0xfffffffe; + } + } + + currentResult = BumpFeeResult::OK; +} + +bool CFeeBumper::signTransaction(CWallet *pWallet) +{ + return pWallet->SignTransaction(mtx); +} + +bool CFeeBumper::commit(CWallet *pWallet) +{ + AssertLockHeld(pWallet->cs_wallet); + if (!vErrors.empty() || currentResult != BumpFeeResult::OK) { + return false; + } + if (txid.IsNull() || !pWallet->mapWallet.count(txid)) { + vErrors.push_back("Invalid or non-wallet transaction id"); + currentResult = BumpFeeResult::MISC_ERROR; + return false; + } + CWalletTx& oldWtx = pWallet->mapWallet[txid]; + + // make sure the transaction still has no descendants and hasen't been mined in the meantime + if (!preconditionChecks(pWallet, oldWtx)) { + return false; + } + + CWalletTx wtxBumped(pWallet, MakeTransactionRef(std::move(mtx))); + // commit/broadcast the tx + CReserveKey reservekey(pWallet); + wtxBumped.mapValue = oldWtx.mapValue; + wtxBumped.mapValue["replaces_txid"] = oldWtx.GetHash().ToString(); + wtxBumped.vOrderForm = oldWtx.vOrderForm; + wtxBumped.strFromAccount = oldWtx.strFromAccount; + wtxBumped.fTimeReceivedIsTxTime = true; + wtxBumped.fFromMe = true; + CValidationState state; + if (!pWallet->CommitTransaction(wtxBumped, reservekey, g_connman.get(), state)) { + // NOTE: CommitTransaction never returns false, so this should never happen. + vErrors.push_back(strprintf("Error: The transaction was rejected! Reason given: %s", state.GetRejectReason())); + return false; + } + + bumpedTxid = wtxBumped.GetHash(); + if (state.IsInvalid()) { + // This can happen if the mempool rejected the transaction. Report + // what happened in the "errors" response. + vErrors.push_back(strprintf("Error: The transaction was rejected: %s", FormatStateMessage(state))); + } + + // mark the original tx as bumped + if (!pWallet->MarkReplaced(oldWtx.GetHash(), wtxBumped.GetHash())) { + // TODO: see if JSON-RPC has a standard way of returning a response + // along with an exception. It would be good to return information about + // wtxBumped to the caller even if marking the original transaction + // replaced does not succeed for some reason. + vErrors.push_back("Error: Created new bumpfee transaction but could not mark the original transaction as replaced."); + } + return true; +} + |