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Calculate and store the number of bytes required to spend an input

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This commit is contained in:
Andrew Chow
2018-03-05 16:37:24 -05:00
parent a34ac6ae07
commit 12ec29d3bb
8 changed files with 127 additions and 68 deletions
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87
src/wallet/wallet.cpp
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@@ -1543,6 +1543,79 @@ int CWalletTx::GetRequestCount() const
return nRequests;
}
// Helper for producing a max-sized low-S signature (eg 72 bytes)
bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout) const
{
// Fill in dummy signatures for fee calculation.
const CScript& scriptPubKey = txout.scriptPubKey;
SignatureData sigdata;
if (!ProduceSignature(DummySignatureCreator(this), scriptPubKey, sigdata))
{
return false;
} else {
UpdateInput(tx_in, sigdata);
}
return true;
}
// Helper for producing a bunch of max-sized low-S signatures (eg 72 bytes)
bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts) const
{
// Fill in dummy signatures for fee calculation.
int nIn = 0;
for (const auto& txout : txouts)
{
if (!DummySignInput(txNew.vin[nIn], txout)) {
return false;
}
nIn++;
}
return true;
}
int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet)
{
std::vector<CTxOut> txouts;
// 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, and the ability to sign.
for (auto& input : tx.vin) {
const auto mi = wallet->mapWallet.find(input.prevout.hash);
if (mi == wallet->mapWallet.end()) {
return -1;
}
assert(input.prevout.n < mi->second.tx->vout.size());
txouts.emplace_back(mi->second.tx->vout[input.prevout.n]);
}
return CalculateMaximumSignedTxSize(tx, wallet, txouts);
}
// txouts needs to be in the order of tx.vin
int64_t CalculateMaximumSignedTxSize(const CTransaction &tx, const CWallet *wallet, const std::vector<CTxOut>& txouts)
{
CMutableTransaction txNew(tx);
if (!wallet->DummySignTx(txNew, txouts)) {
// This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
// implies that we can sign for every input.
return -1;
}
return GetVirtualTransactionSize(txNew);
}
int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* wallet)
{
CMutableTransaction txn;
txn.vin.push_back(CTxIn(COutPoint()));
if (!wallet->DummySignInput(txn.vin[0], txout)) {
// This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
// implies that we can sign for every input.
return -1;
}
return GetVirtualTransactionInputSize(txn.vin[0]);
}
void CWalletTx::GetAmounts(std::list<COutputEntry>& listReceived,
std::list<COutputEntry>& listSent, CAmount& nFee, std::string& strSentAccount, const isminefilter& filter) const
{
@@ -2752,7 +2825,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
assert(txNew.nLockTime < LOCKTIME_THRESHOLD);
FeeCalculation feeCalc;
CAmount nFeeNeeded;
unsigned int nBytes;
int nBytes;
{
std::set<CInputCoin> setCoins;
LOCK2(cs_main, cs_wallet);
@@ -2903,20 +2976,12 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
txNew.vin.push_back(CTxIn(coin.outpoint,CScript(),
nSequence));
// Fill in dummy signatures for fee calculation.
if (!DummySignTx(txNew, setCoins)) {
nBytes = CalculateMaximumSignedTxSize(txNew, this);
if (nBytes < 0) {
strFailReason = _("Signing transaction failed");
return false;
}
nBytes = GetVirtualTransactionSize(txNew);
// Remove scriptSigs to eliminate the fee calculation dummy signatures
for (auto& vin : txNew.vin) {
vin.scriptSig = CScript();
vin.scriptWitness.SetNull();
}
nFeeNeeded = GetMinimumFee(nBytes, coin_control, ::mempool, ::feeEstimator, &feeCalc);
if (feeCalc.reason == FeeReason::FALLBACK && !g_wallet_allow_fallback_fee) {
// eventually allow a fallback fee