Jorge Timón
9 years ago
13 changed files with 336 additions and 297 deletions
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// Copyright (c) 2017-2017 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 "tx_verify.h" |
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#include "consensus.h" |
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#include "primitives/transaction.h" |
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#include "script/interpreter.h" |
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#include "validation.h" |
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// TODO remove the following dependencies
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#include "chain.h" |
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#include "coins.h" |
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#include "utilmoneystr.h" |
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bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime) |
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{ |
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if (tx.nLockTime == 0) |
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return true; |
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if ((int64_t)tx.nLockTime < ((int64_t)tx.nLockTime < LOCKTIME_THRESHOLD ? (int64_t)nBlockHeight : nBlockTime)) |
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return true; |
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for (const auto& txin : tx.vin) { |
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if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL)) |
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return false; |
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} |
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return true; |
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} |
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std::pair<int, int64_t> CalculateSequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block) |
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{ |
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assert(prevHeights->size() == tx.vin.size()); |
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// Will be set to the equivalent height- and time-based nLockTime
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// values that would be necessary to satisfy all relative lock-
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// time constraints given our view of block chain history.
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// The semantics of nLockTime are the last invalid height/time, so
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// use -1 to have the effect of any height or time being valid.
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int nMinHeight = -1; |
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int64_t nMinTime = -1; |
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// tx.nVersion is signed integer so requires cast to unsigned otherwise
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// we would be doing a signed comparison and half the range of nVersion
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// wouldn't support BIP 68.
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bool fEnforceBIP68 = static_cast<uint32_t>(tx.nVersion) >= 2 |
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&& flags & LOCKTIME_VERIFY_SEQUENCE; |
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// Do not enforce sequence numbers as a relative lock time
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// unless we have been instructed to
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if (!fEnforceBIP68) { |
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return std::make_pair(nMinHeight, nMinTime); |
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} |
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for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) { |
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const CTxIn& txin = tx.vin[txinIndex]; |
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// Sequence numbers with the most significant bit set are not
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// treated as relative lock-times, nor are they given any
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// consensus-enforced meaning at this point.
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if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) { |
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// The height of this input is not relevant for sequence locks
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(*prevHeights)[txinIndex] = 0; |
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continue; |
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} |
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int nCoinHeight = (*prevHeights)[txinIndex]; |
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if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) { |
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int64_t nCoinTime = block.GetAncestor(std::max(nCoinHeight-1, 0))->GetMedianTimePast(); |
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// NOTE: Subtract 1 to maintain nLockTime semantics
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// BIP 68 relative lock times have the semantics of calculating
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// the first block or time at which the transaction would be
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// valid. When calculating the effective block time or height
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// for the entire transaction, we switch to using the
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// semantics of nLockTime which is the last invalid block
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// time or height. Thus we subtract 1 from the calculated
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// time or height.
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// Time-based relative lock-times are measured from the
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// smallest allowed timestamp of the block containing the
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// txout being spent, which is the median time past of the
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// block prior.
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nMinTime = std::max(nMinTime, nCoinTime + (int64_t)((txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) << CTxIn::SEQUENCE_LOCKTIME_GRANULARITY) - 1); |
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} else { |
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nMinHeight = std::max(nMinHeight, nCoinHeight + (int)(txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) - 1); |
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} |
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} |
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return std::make_pair(nMinHeight, nMinTime); |
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} |
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bool EvaluateSequenceLocks(const CBlockIndex& block, std::pair<int, int64_t> lockPair) |
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{ |
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assert(block.pprev); |
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int64_t nBlockTime = block.pprev->GetMedianTimePast(); |
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if (lockPair.first >= block.nHeight || lockPair.second >= nBlockTime) |
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return false; |
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return true; |
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} |
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bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block) |
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{ |
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return EvaluateSequenceLocks(block, CalculateSequenceLocks(tx, flags, prevHeights, block)); |
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} |
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unsigned int GetLegacySigOpCount(const CTransaction& tx) |
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{ |
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unsigned int nSigOps = 0; |
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for (const auto& txin : tx.vin) |
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{ |
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nSigOps += txin.scriptSig.GetSigOpCount(false); |
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} |
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for (const auto& txout : tx.vout) |
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{ |
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nSigOps += txout.scriptPubKey.GetSigOpCount(false); |
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} |
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return nSigOps; |
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} |
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unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& inputs) |
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{ |
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if (tx.IsCoinBase()) |
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return 0; |
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unsigned int nSigOps = 0; |
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for (unsigned int i = 0; i < tx.vin.size(); i++) |
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{ |
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const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]); |
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if (prevout.scriptPubKey.IsPayToScriptHash()) |
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nSigOps += prevout.scriptPubKey.GetSigOpCount(tx.vin[i].scriptSig); |
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} |
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return nSigOps; |
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} |
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int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags) |
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{ |
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int64_t nSigOps = GetLegacySigOpCount(tx) * WITNESS_SCALE_FACTOR; |
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if (tx.IsCoinBase()) |
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return nSigOps; |
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if (flags & SCRIPT_VERIFY_P2SH) { |
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nSigOps += GetP2SHSigOpCount(tx, inputs) * WITNESS_SCALE_FACTOR; |
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} |
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for (unsigned int i = 0; i < tx.vin.size(); i++) |
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{ |
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const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]); |
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nSigOps += CountWitnessSigOps(tx.vin[i].scriptSig, prevout.scriptPubKey, &tx.vin[i].scriptWitness, flags); |
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} |
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return nSigOps; |
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} |
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bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fCheckDuplicateInputs) |
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{ |
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// Basic checks that don't depend on any context
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if (tx.vin.empty()) |
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return state.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty"); |
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if (tx.vout.empty()) |
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return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty"); |
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// Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
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if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_BASE_SIZE) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize"); |
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// Check for negative or overflow output values
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CAmount nValueOut = 0; |
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for (const auto& txout : tx.vout) |
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{ |
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if (txout.nValue < 0) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative"); |
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if (txout.nValue > MAX_MONEY) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge"); |
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nValueOut += txout.nValue; |
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if (!MoneyRange(nValueOut)) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge"); |
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} |
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// Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
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if (fCheckDuplicateInputs) { |
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std::set<COutPoint> vInOutPoints; |
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for (const auto& txin : tx.vin) |
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{ |
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if (!vInOutPoints.insert(txin.prevout).second) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate"); |
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} |
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} |
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if (tx.IsCoinBase()) |
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{ |
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if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100) |
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return state.DoS(100, false, REJECT_INVALID, "bad-cb-length"); |
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} |
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else |
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{ |
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for (const auto& txin : tx.vin) |
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if (txin.prevout.IsNull()) |
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return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null"); |
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} |
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return true; |
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} |
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bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight) |
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{ |
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// This doesn't trigger the DoS code on purpose; if it did, it would make it easier
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// for an attacker to attempt to split the network.
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if (!inputs.HaveInputs(tx)) |
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return state.Invalid(false, 0, "", "Inputs unavailable"); |
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CAmount nValueIn = 0; |
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CAmount nFees = 0; |
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for (unsigned int i = 0; i < tx.vin.size(); i++) |
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{ |
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const COutPoint &prevout = tx.vin[i].prevout; |
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const CCoins *coins = inputs.AccessCoins(prevout.hash); |
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assert(coins); |
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// If prev is coinbase, check that it's matured
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if (coins->IsCoinBase()) { |
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if (nSpendHeight - coins->nHeight < COINBASE_MATURITY) |
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return state.Invalid(false, |
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REJECT_INVALID, "bad-txns-premature-spend-of-coinbase", |
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strprintf("tried to spend coinbase at depth %d", nSpendHeight - coins->nHeight)); |
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} |
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// Check for negative or overflow input values
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nValueIn += coins->vout[prevout.n].nValue; |
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if (!MoneyRange(coins->vout[prevout.n].nValue) || !MoneyRange(nValueIn)) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputvalues-outofrange"); |
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} |
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if (nValueIn < tx.GetValueOut()) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-in-belowout", false, |
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strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(tx.GetValueOut()))); |
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// Tally transaction fees
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CAmount nTxFee = nValueIn - tx.GetValueOut(); |
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if (nTxFee < 0) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-negative"); |
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nFees += nTxFee; |
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if (!MoneyRange(nFees)) |
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return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-outofrange"); |
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return true; |
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} |
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@ -0,0 +1,78 @@ |
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// Copyright (c) 2017-2017 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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#ifndef BITCOIN_CONSENSUS_TX_VERIFY_H |
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#define BITCOIN_CONSENSUS_TX_VERIFY_H |
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#include <stdint.h> |
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#include <vector> |
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class CBlockIndex; |
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class CCoinsViewCache; |
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class CTransaction; |
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class CValidationState; |
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/** Transaction validation functions */ |
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/** Context-independent validity checks */ |
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bool CheckTransaction(const CTransaction& tx, CValidationState& state, bool fCheckDuplicateInputs=true); |
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namespace Consensus { |
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/**
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* Check whether all inputs of this transaction are valid (no double spends and amounts) |
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* This does not modify the UTXO set. This does not check scripts and sigs. |
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* Preconditions: tx.IsCoinBase() is false. |
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*/ |
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bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight); |
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} // namespace Consensus
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/** Auxiliary functions for transaction validation (ideally should not be exposed) */ |
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/**
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* Count ECDSA signature operations the old-fashioned (pre-0.6) way |
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* @return number of sigops this transaction's outputs will produce when spent |
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* @see CTransaction::FetchInputs |
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*/ |
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unsigned int GetLegacySigOpCount(const CTransaction& tx); |
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/**
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* Count ECDSA signature operations in pay-to-script-hash inputs. |
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* |
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* @param[in] mapInputs Map of previous transactions that have outputs we're spending |
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* @return maximum number of sigops required to validate this transaction's inputs |
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* @see CTransaction::FetchInputs |
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*/ |
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unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& mapInputs); |
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/**
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* Compute total signature operation cost of a transaction. |
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* @param[in] tx Transaction for which we are computing the cost |
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* @param[in] inputs Map of previous transactions that have outputs we're spending |
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* @param[out] flags Script verification flags |
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* @return Total signature operation cost of tx |
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*/ |
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int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags); |
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/**
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* Check if transaction is final and can be included in a block with the |
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* specified height and time. Consensus critical. |
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*/ |
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bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime); |
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/**
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* Calculates the block height and previous block's median time past at |
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* which the transaction will be considered final in the context of BIP 68. |
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* Also removes from the vector of input heights any entries which did not |
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* correspond to sequence locked inputs as they do not affect the calculation. |
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*/ |
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std::pair<int, int64_t> CalculateSequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block); |
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bool EvaluateSequenceLocks(const CBlockIndex& block, std::pair<int, int64_t> lockPair); |
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/**
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* Check if transaction is final per BIP 68 sequence numbers and can be included in a block. |
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* Consensus critical. Takes as input a list of heights at which tx's inputs (in order) confirmed. |
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*/ |
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bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block); |
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#endif // BITCOIN_CONSENSUS_TX_VERIFY_H
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