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Consensus: Minimal way to move dust out of consensus

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This commit is contained in:
Jorge Timón 2016-10-14 17:49:05 +02:00
parent 35da2aeed7
commit 330bb5a456
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GPG key ID: 8866C18EA1C944A2
8 changed files with 54 additions and 50 deletions
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39
src/policy/policy.cpp
View file

@ -15,6 +15,43 @@
#include <boost/foreach.hpp>
CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee)
{
// "Dust" is defined in terms of dustRelayFee,
// which has units satoshis-per-kilobyte.
// If you'd pay more than 1/3 in fees
// to spend something, then we consider it dust.
// A typical spendable non-segwit txout is 34 bytes big, and will
// need a CTxIn of at least 148 bytes to spend:
// so dust is a spendable txout less than
// 546*dustRelayFee/1000 (in satoshis).
// A typical spendable segwit txout is 31 bytes big, and will
// need a CTxIn of at least 67 bytes to spend:
// so dust is a spendable txout less than
// 294*dustRelayFee/1000 (in satoshis).
if (txout.scriptPubKey.IsUnspendable())
return 0;
size_t nSize = GetSerializeSize(txout, SER_DISK, 0);
int witnessversion = 0;
std::vector<unsigned char> witnessprogram;
if (txout.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
// sum the sizes of the parts of a transaction input
// with 75% segwit discount applied to the script size.
nSize += (32 + 4 + 1 + (107 / WITNESS_SCALE_FACTOR) + 4);
} else {
nSize += (32 + 4 + 1 + 107 + 4); // the 148 mentioned above
}
return 3 * dustRelayFee.GetFee(nSize);
}
bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee)
{
return (txout.nValue < GetDustThreshold(txout, dustRelayFee));
}
/**
* Check transaction inputs to mitigate two
* potential denial-of-service attacks:
@ -106,7 +143,7 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnes
else if ((whichType == TX_MULTISIG) && (!fIsBareMultisigStd)) {
reason = "bare-multisig";
return false;
} else if (txout.IsDust(dustRelayFee)) {
} else if (IsDust(txout, ::dustRelayFee)) {
reason = "dust";
return false;
}

5
src/policy/policy.h
View file

@ -13,6 +13,7 @@
#include <string>
class CCoinsViewCache;
class CTxOut;
/** Default for -blockmaxsize, which controls the maximum size of block the mining code will create **/
static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
@ -72,6 +73,10 @@ static const unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_
static const unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS = LOCKTIME_VERIFY_SEQUENCE |
LOCKTIME_MEDIAN_TIME_PAST;
CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);
bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType, const bool witnessEnabled = false);
/**
* Check for standard transaction types

37
src/primitives/transaction.h
View file

@ -161,43 +161,6 @@ public:
return (nValue == -1);
}
CAmount GetDustThreshold(const CFeeRate &minRelayTxFee) const
{
// "Dust" is defined in terms of CTransaction::minRelayTxFee,
// which has units satoshis-per-kilobyte.
// If you'd pay more than 1/3 in fees
// to spend something, then we consider it dust.
// A typical spendable non-segwit txout is 34 bytes big, and will
// need a CTxIn of at least 148 bytes to spend:
// so dust is a spendable txout less than
// 546*minRelayTxFee/1000 (in satoshis).
// A typical spendable segwit txout is 31 bytes big, and will
// need a CTxIn of at least 67 bytes to spend:
// so dust is a spendable txout less than
// 294*minRelayTxFee/1000 (in satoshis).
if (scriptPubKey.IsUnspendable())
return 0;
size_t nSize = GetSerializeSize(*this, SER_DISK, 0);
int witnessversion = 0;
std::vector<unsigned char> witnessprogram;
if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
// sum the sizes of the parts of a transaction input
// with 75% segwit discount applied to the script size.
nSize += (32 + 4 + 1 + (107 / WITNESS_SCALE_FACTOR) + 4);
} else {
nSize += (32 + 4 + 1 + 107 + 4); // the 148 mentioned above
}
return 3 * minRelayTxFee.GetFee(nSize);
}
bool IsDust(const CFeeRate &minRelayTxFee) const
{
return (nValue < GetDustThreshold(minRelayTxFee));
}
friend bool operator==(const CTxOut& a, const CTxOut& b)
{
return (a.nValue == b.nValue &&

7
src/qt/coincontroldialog.cpp
View file

@ -434,8 +434,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
{
CTxOut txout(amount, (CScript)std::vector<unsigned char>(24, 0));
txDummy.vout.push_back(txout);
if (txout.IsDust(dustRelayFee))
fDust = true;
fDust |= IsDust(txout, ::dustRelayFee);
}
}
@ -527,10 +526,10 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
if (nChange > 0 && nChange < MIN_CHANGE)
{
CTxOut txout(nChange, (CScript)std::vector<unsigned char>(24, 0));
if (txout.IsDust(dustRelayFee))
if (IsDust(txout, ::dustRelayFee))
{
if (CoinControlDialog::fSubtractFeeFromAmount) // dust-change will be raised until no dust
nChange = txout.GetDustThreshold(dustRelayFee);
nChange = GetDustThreshold(txout, ::dustRelayFee);
else
{
nPayFee += nChange;

2
src/qt/guiutil.cpp
View file

@ -251,7 +251,7 @@ bool isDust(const QString& address, const CAmount& amount)
CTxDestination dest = CBitcoinAddress(address.toStdString()).Get();
CScript script = GetScriptForDestination(dest);
CTxOut txOut(amount, script);
return txOut.IsDust(dustRelayFee);
return IsDust(txOut, ::dustRelayFee);
}
QString HtmlEscape(const QString& str, bool fMultiLine)

2
src/qt/paymentserver.cpp
View file

@ -580,7 +580,7 @@ bool PaymentServer::processPaymentRequest(const PaymentRequestPlus& request, Sen
// Extract and check amounts
CTxOut txOut(sendingTo.second, sendingTo.first);
if (txOut.IsDust(dustRelayFee)) {
if (IsDust(txOut, ::dustRelayFee)) {
Q_EMIT message(tr("Payment request error"), tr("Requested payment amount of %1 is too small (considered dust).")
.arg(BitcoinUnits::formatWithUnit(optionsModel->getDisplayUnit(), sendingTo.second)),
CClientUIInterface::MSG_ERROR);

2
src/wallet/feebumper.cpp
View file

@ -214,7 +214,7 @@ CFeeBumper::CFeeBumper(const CWallet *pWallet, const uint256 txidIn, int newConf
// If the output would become dust, discard it (converting the dust to fee)
poutput->nValue -= nDelta;
if (poutput->nValue <= poutput->GetDustThreshold(::dustRelayFee)) {
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);

10
src/wallet/wallet.cpp
View file

@ -2449,7 +2449,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
}
}
if (txout.IsDust(dustRelayFee))
if (IsDust(txout, ::dustRelayFee))
{
if (recipient.fSubtractFeeFromAmount && nFeeRet > 0)
{
@ -2514,16 +2514,16 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
// We do not move dust-change to fees, because the sender would end up paying more than requested.
// This would be against the purpose of the all-inclusive feature.
// So instead we raise the change and deduct from the recipient.
if (nSubtractFeeFromAmount > 0 && newTxOut.IsDust(dustRelayFee))
if (nSubtractFeeFromAmount > 0 && IsDust(newTxOut, ::dustRelayFee))
{
CAmount nDust = newTxOut.GetDustThreshold(dustRelayFee) - newTxOut.nValue;
CAmount nDust = GetDustThreshold(newTxOut, ::dustRelayFee) - newTxOut.nValue;
newTxOut.nValue += nDust; // raise change until no more dust
for (unsigned int i = 0; i < vecSend.size(); i++) // subtract from first recipient
{
if (vecSend[i].fSubtractFeeFromAmount)
{
txNew.vout[i].nValue -= nDust;
if (txNew.vout[i].IsDust(dustRelayFee))
if (IsDust(txNew.vout[i], ::dustRelayFee))
{
strFailReason = _("The transaction amount is too small to send after the fee has been deducted");
return false;
@ -2535,7 +2535,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
// Never create dust outputs; if we would, just
// add the dust to the fee.
if (newTxOut.IsDust(dustRelayFee))
if (IsDust(newTxOut, ::dustRelayFee))
{
nChangePosInOut = -1;
nFeeRet += nChange;