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validation.cpp
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validation.cpp
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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 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 "validation.h"
#include "arith_uint256.h"
#include "chain.h"
#include "chainparams.h"
#include "checkpoints.h"
#include "checkqueue.h"
#include "consensus/consensus.h"
#include "consensus/merkle.h"
#include "consensus/tx_verify.h"
#include "consensus/validation.h"
#include "cuckoocache.h"
#include "fs.h"
#include "hash.h"
#include "init.h"
#include "policy/fees.h"
#include "policy/policy.h"
#include "policy/rbf.h"
#include "pow.h"
#include "primitives/block.h"
#include "primitives/transaction.h"
#include "random.h"
#include "reverse_iterator.h"
#include "script/script.h"
#include "script/sigcache.h"
#include "script/standard.h"
#include "timedata.h"
#include "tinyformat.h"
#include "txdb.h"
#include "txmempool.h"
#include "ui_interface.h"
#include "undo.h"
#include "util.h"
#include "utilmoneystr.h"
#include "utilstrencodings.h"
#include "validationinterface.h"
#include "versionbits.h"
#include "warnings.h"
#include <atomic>
#include <sstream>
#include <boost/algorithm/string/replace.hpp>
#include <boost/algorithm/string/join.hpp>
#include <boost/thread.hpp>
#if defined(NDEBUG)
# error "Bitcoin cannot be compiled without assertions."
#endif
#define MICRO 0.000001
#define MILLI 0.001
/**
* Global state
*/
CCriticalSection cs_main;
BlockMap mapBlockIndex;
CChain chainActive;
CBlockIndex *pindexBestHeader = nullptr;
CWaitableCriticalSection csBestBlock;
CConditionVariable cvBlockChange;
int nScriptCheckThreads = 0;
std::atomic_bool fImporting(false);
std::atomic_bool fReindex(false);
bool fTxIndex = false;
bool fHavePruned = false;
bool fPruneMode = false;
bool fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
bool fRequireStandard = true;
bool fCheckBlockIndex = false;
bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
size_t nCoinCacheUsage = 5000 * 300;
uint64_t nPruneTarget = 0;
int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
uint256 hashAssumeValid;
arith_uint256 nMinimumChainWork;
CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
CBlockPolicyEstimator feeEstimator;
CTxMemPool mempool(&feeEstimator);
static void CheckBlockIndex(const Consensus::Params& consensusParams);
/** Constant stuff for coinbase transactions we create: */
CScript COINBASE_FLAGS;
const std::string strMessageMagic = "Bitcoin Signed Message:\n";
// Internal stuff
namespace {
struct CBlockIndexWorkComparator
{
bool operator()(const CBlockIndex *pa, const CBlockIndex *pb) const {
// First sort by most total work, ...
if (pa->nChainWork > pb->nChainWork) return false;
if (pa->nChainWork < pb->nChainWork) return true;
// ... then by earliest time received, ...
if (pa->nSequenceId < pb->nSequenceId) return false;
if (pa->nSequenceId > pb->nSequenceId) return true;
// Use pointer address as tie breaker (should only happen with blocks
// loaded from disk, as those all have id 0).
if (pa < pb) return false;
if (pa > pb) return true;
// Identical blocks.
return false;
}
};
CBlockIndex *pindexBestInvalid;
/**
* The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for itself and all ancestors) and
* as good as our current tip or better. Entries may be failed, though, and pruning nodes may be
* missing the data for the block.
*/
std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
/** All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
* Pruned nodes may have entries where B is missing data.
*/
std::multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
CCriticalSection cs_LastBlockFile;
std::vector<CBlockFileInfo> vinfoBlockFile;
int nLastBlockFile = 0;
/** Global flag to indicate we should check to see if there are
* block/undo files that should be deleted. Set on startup
* or if we allocate more file space when we're in prune mode
*/
bool fCheckForPruning = false;
/**
* Every received block is assigned a unique and increasing identifier, so we
* know which one to give priority in case of a fork.
*/
CCriticalSection cs_nBlockSequenceId;
/** Blocks loaded from disk are assigned id 0, so start the counter at 1. */
int32_t nBlockSequenceId = 1;
/** Decreasing counter (used by subsequent preciousblock calls). */
int32_t nBlockReverseSequenceId = -1;
/** chainwork for the last block that preciousblock has been applied to. */
arith_uint256 nLastPreciousChainwork = 0;
/** Dirty block index entries. */
std::set<CBlockIndex*> setDirtyBlockIndex;
/** Dirty block file entries. */
std::set<int> setDirtyFileInfo;
} // anon namespace
CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
{
// Find the first block the caller has in the main chain
for (const uint256& hash : locator.vHave) {
BlockMap::iterator mi = mapBlockIndex.find(hash);
if (mi != mapBlockIndex.end())
{
CBlockIndex* pindex = (*mi).second;
if (chain.Contains(pindex))
return pindex;
if (pindex->GetAncestor(chain.Height()) == chain.Tip()) {
return chain.Tip();
}
}
}
return chain.Genesis();
}
CCoinsViewDB *pcoinsdbview = nullptr;
CCoinsViewCache *pcoinsTip = nullptr;
CBlockTreeDB *pblocktree = nullptr;
enum FlushStateMode {
FLUSH_STATE_NONE,
FLUSH_STATE_IF_NEEDED,
FLUSH_STATE_PERIODIC,
FLUSH_STATE_ALWAYS
};
// See definition for documentation
static bool FlushStateToDisk(const CChainParams& chainParams, CValidationState &state, FlushStateMode mode, int nManualPruneHeight=0);
static void FindFilesToPruneManual(std::set<int>& setFilesToPrune, int nManualPruneHeight);
static void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight);
bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheSigStore, bool cacheFullScriptStore, PrecomputedTransactionData& txdata, std::vector<CScriptCheck> *pvChecks = nullptr);
static FILE* OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly = false);
bool CheckFinalTx(const CTransaction &tx, int flags)
{
AssertLockHeld(cs_main);
// By convention a negative value for flags indicates that the
// current network-enforced consensus rules should be used. In
// a future soft-fork scenario that would mean checking which
// rules would be enforced for the next block and setting the
// appropriate flags. At the present time no soft-forks are
// scheduled, so no flags are set.
flags = std::max(flags, 0);
// CheckFinalTx() uses chainActive.Height()+1 to evaluate
// nLockTime because when IsFinalTx() is called within
// CBlock::AcceptBlock(), the height of the block *being*
// evaluated is what is used. Thus if we want to know if a
// transaction can be part of the *next* block, we need to call
// IsFinalTx() with one more than chainActive.Height().
const int nBlockHeight = chainActive.Height() + 1;
// BIP113 requires that time-locked transactions have nLockTime set to
// less than the median time of the previous block they're contained in.
// When the next block is created its previous block will be the current
// chain tip, so we use that to calculate the median time passed to
// IsFinalTx() if LOCKTIME_MEDIAN_TIME_PAST is set.
const int64_t nBlockTime = (flags & LOCKTIME_MEDIAN_TIME_PAST)
? chainActive.Tip()->GetMedianTimePast()
: GetAdjustedTime();
return IsFinalTx(tx, nBlockHeight, nBlockTime);
}
bool TestLockPointValidity(const LockPoints* lp)
{
AssertLockHeld(cs_main);
assert(lp);
// If there are relative lock times then the maxInputBlock will be set
// If there are no relative lock times, the LockPoints don't depend on the chain
if (lp->maxInputBlock) {
// Check whether chainActive is an extension of the block at which the LockPoints
// calculation was valid. If not LockPoints are no longer valid
if (!chainActive.Contains(lp->maxInputBlock)) {
return false;
}
}
// LockPoints still valid
return true;
}
bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp, bool useExistingLockPoints)
{
AssertLockHeld(cs_main);
AssertLockHeld(mempool.cs);
CBlockIndex* tip = chainActive.Tip();
assert(tip != nullptr);
CBlockIndex index;
index.pprev = tip;
// CheckSequenceLocks() uses chainActive.Height()+1 to evaluate
// height based locks because when SequenceLocks() is called within
// ConnectBlock(), the height of the block *being*
// evaluated is what is used.
// Thus if we want to know if a transaction can be part of the
// *next* block, we need to use one more than chainActive.Height()
index.nHeight = tip->nHeight + 1;
std::pair<int, int64_t> lockPair;
if (useExistingLockPoints) {
assert(lp);
lockPair.first = lp->height;
lockPair.second = lp->time;
}
else {
// pcoinsTip contains the UTXO set for chainActive.Tip()
CCoinsViewMemPool viewMemPool(pcoinsTip, mempool);
std::vector<int> prevheights;
prevheights.resize(tx.vin.size());
for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
const CTxIn& txin = tx.vin[txinIndex];
Coin coin;
if (!viewMemPool.GetCoin(txin.prevout, coin)) {
return error("%s: Missing input", __func__);
}
if (coin.nHeight == MEMPOOL_HEIGHT) {
// Assume all mempool transaction confirm in the next block
prevheights[txinIndex] = tip->nHeight + 1;
} else {
prevheights[txinIndex] = coin.nHeight;
}
}
lockPair = CalculateSequenceLocks(tx, flags, &prevheights, index);
if (lp) {
lp->height = lockPair.first;
lp->time = lockPair.second;
// Also store the hash of the block with the highest height of
// all the blocks which have sequence locked prevouts.
// This hash needs to still be on the chain
// for these LockPoint calculations to be valid
// Note: It is impossible to correctly calculate a maxInputBlock
// if any of the sequence locked inputs depend on unconfirmed txs,
// except in the special case where the relative lock time/height
// is 0, which is equivalent to no sequence lock. Since we assume
// input height of tip+1 for mempool txs and test the resulting
// lockPair from CalculateSequenceLocks against tip+1. We know
// EvaluateSequenceLocks will fail if there was a non-zero sequence
// lock on a mempool input, so we can use the return value of
// CheckSequenceLocks to indicate the LockPoints validity
int maxInputHeight = 0;
for (int height : prevheights) {
// Can ignore mempool inputs since we'll fail if they had non-zero locks
if (height != tip->nHeight+1) {
maxInputHeight = std::max(maxInputHeight, height);
}
}
lp->maxInputBlock = tip->GetAncestor(maxInputHeight);
}
}
return EvaluateSequenceLocks(index, lockPair);
}
// Returns the script flags which should be checked for a given block
static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& chainparams);
static void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age) {
int expired = pool.Expire(GetTime() - age);
if (expired != 0) {
LogPrint(BCLog::MEMPOOL, "Expired %i transactions from the memory pool\n", expired);
}
std::vector<COutPoint> vNoSpendsRemaining;
pool.TrimToSize(limit, &vNoSpendsRemaining);
for (const COutPoint& removed : vNoSpendsRemaining)
pcoinsTip->Uncache(removed);
}
/** Convert CValidationState to a human-readable message for logging */
std::string FormatStateMessage(const CValidationState &state)
{
return strprintf("%s%s (code %i)",
state.GetRejectReason(),
state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage(),
state.GetRejectCode());
}
static bool IsCurrentForFeeEstimation()
{
AssertLockHeld(cs_main);
if (IsInitialBlockDownload())
return false;
if (chainActive.Tip()->GetBlockTime() < (GetTime() - MAX_FEE_ESTIMATION_TIP_AGE))
return false;
if (chainActive.Height() < pindexBestHeader->nHeight - 1)
return false;
return true;
}
/* Make mempool consistent after a reorg, by re-adding or recursively erasing
* disconnected block transactions from the mempool, and also removing any
* other transactions from the mempool that are no longer valid given the new
* tip/height.
*
* Note: we assume that disconnectpool only contains transactions that are NOT
* confirmed in the current chain nor already in the mempool (otherwise,
* in-mempool descendants of such transactions would be removed).
*
* Passing fAddToMempool=false will skip trying to add the transactions back,
* and instead just erase from the mempool as needed.
*/
void UpdateMempoolForReorg(DisconnectedBlockTransactions &disconnectpool, bool fAddToMempool)
{
AssertLockHeld(cs_main);
std::vector<uint256> vHashUpdate;
// disconnectpool's insertion_order index sorts the entries from
// oldest to newest, but the oldest entry will be the last tx from the
// latest mined block that was disconnected.
// Iterate disconnectpool in reverse, so that we add transactions
// back to the mempool starting with the earliest transaction that had
// been previously seen in a block.
auto it = disconnectpool.queuedTx.get<insertion_order>().rbegin();
while (it != disconnectpool.queuedTx.get<insertion_order>().rend()) {
// ignore validation errors in resurrected transactions
CValidationState stateDummy;
if (!fAddToMempool || (*it)->IsCoinBase() ||
!AcceptToMemoryPool(mempool, stateDummy, *it, nullptr /* pfMissingInputs */,
nullptr /* plTxnReplaced */, true /* bypass_limits */, 0 /* nAbsurdFee */)) {
// If the transaction doesn't make it in to the mempool, remove any
// transactions that depend on it (which would now be orphans).
mempool.removeRecursive(**it, MemPoolRemovalReason::REORG);
} else if (mempool.exists((*it)->GetHash())) {
vHashUpdate.push_back((*it)->GetHash());
}
++it;
}
disconnectpool.queuedTx.clear();
// AcceptToMemoryPool/addUnchecked all assume that new mempool entries have
// no in-mempool children, which is generally not true when adding
// previously-confirmed transactions back to the mempool.
// UpdateTransactionsFromBlock finds descendants of any transactions in
// the disconnectpool that were added back and cleans up the mempool state.
mempool.UpdateTransactionsFromBlock(vHashUpdate);
// We also need to remove any now-immature transactions
mempool.removeForReorg(pcoinsTip, chainActive.Tip()->nHeight + 1, STANDARD_LOCKTIME_VERIFY_FLAGS);
// Re-limit mempool size, in case we added any transactions
LimitMempoolSize(mempool, gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
}
// Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
// were somehow broken and returning the wrong scriptPubKeys
static bool CheckInputsFromMempoolAndCache(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &view, CTxMemPool& pool,
unsigned int flags, bool cacheSigStore, PrecomputedTransactionData& txdata) {
AssertLockHeld(cs_main);
// pool.cs should be locked already, but go ahead and re-take the lock here
// to enforce that mempool doesn't change between when we check the view
// and when we actually call through to CheckInputs
LOCK(pool.cs);
assert(!tx.IsCoinBase());
for (const CTxIn& txin : tx.vin) {
const Coin& coin = view.AccessCoin(txin.prevout);
// At this point we haven't actually checked if the coins are all
// available (or shouldn't assume we have, since CheckInputs does).
// So we just return failure if the inputs are not available here,
// and then only have to check equivalence for available inputs.
if (coin.IsSpent()) return false;
const CTransactionRef& txFrom = pool.get(txin.prevout.hash);
if (txFrom) {
assert(txFrom->GetHash() == txin.prevout.hash);
assert(txFrom->vout.size() > txin.prevout.n);
assert(txFrom->vout[txin.prevout.n] == coin.out);
} else {
const Coin& coinFromDisk = pcoinsTip->AccessCoin(txin.prevout);
assert(!coinFromDisk.IsSpent());
assert(coinFromDisk.out == coin.out);
}
}
return CheckInputs(tx, state, view, true, flags, cacheSigStore, true, txdata);
}
static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool& pool, CValidationState& state, const CTransactionRef& ptx,
bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
bool bypass_limits, const CAmount& nAbsurdFee, std::vector<COutPoint>& coins_to_uncache)
{
const CTransaction& tx = *ptx;
const uint256 hash = tx.GetHash();
AssertLockHeld(cs_main);
if (pfMissingInputs)
*pfMissingInputs = false;
if (!CheckTransaction(tx, state))
return false; // state filled in by CheckTransaction
// Coinbase is only valid in a block, not as a loose transaction
if (tx.IsCoinBase())
return state.DoS(100, false, REJECT_INVALID, "coinbase");
// Reject transactions with witness before segregated witness activates (override with -prematurewitness)
bool witnessEnabled = IsWitnessEnabled(chainActive.Tip(), chainparams.GetConsensus());
if (!gArgs.GetBoolArg("-prematurewitness", false) && tx.HasWitness() && !witnessEnabled) {
return state.DoS(0, false, REJECT_NONSTANDARD, "no-witness-yet", true);
}
// Rather not work on nonstandard transactions (unless -testnet/-regtest)
std::string reason;
if (fRequireStandard && !IsStandardTx(tx, reason, witnessEnabled))
return state.DoS(0, false, REJECT_NONSTANDARD, reason);
// Only accept nLockTime-using transactions that can be mined in the next
// block; we don't want our mempool filled up with transactions that can't
// be mined yet.
if (!CheckFinalTx(tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
return state.DoS(0, false, REJECT_NONSTANDARD, "non-final");
// is it already in the memory pool?
if (pool.exists(hash)) {
return state.Invalid(false, REJECT_DUPLICATE, "txn-already-in-mempool");
}
// Check for conflicts with in-memory transactions
std::set<uint256> setConflicts;
{
LOCK(pool.cs); // protect pool.mapNextTx
for (const CTxIn &txin : tx.vin)
{
auto itConflicting = pool.mapNextTx.find(txin.prevout);
if (itConflicting != pool.mapNextTx.end())
{
const CTransaction *ptxConflicting = itConflicting->second;
if (!setConflicts.count(ptxConflicting->GetHash()))
{
// Allow opt-out of transaction replacement by setting
// nSequence > MAX_BIP125_RBF_SEQUENCE (SEQUENCE_FINAL-2) on all inputs.
//
// SEQUENCE_FINAL-1 is picked to still allow use of nLockTime by
// non-replaceable transactions. All inputs rather than just one
// is for the sake of multi-party protocols, where we don't
// want a single party to be able to disable replacement.
//
// The opt-out ignores descendants as anyone relying on
// first-seen mempool behavior should be checking all
// unconfirmed ancestors anyway; doing otherwise is hopelessly
// insecure.
bool fReplacementOptOut = true;
if (fEnableReplacement)
{
for (const CTxIn &_txin : ptxConflicting->vin)
{
if (_txin.nSequence <= MAX_BIP125_RBF_SEQUENCE)
{
fReplacementOptOut = false;
break;
}
}
}
if (fReplacementOptOut) {
return state.Invalid(false, REJECT_DUPLICATE, "txn-mempool-conflict");
}
setConflicts.insert(ptxConflicting->GetHash());
}
}
}
}
{
CCoinsView dummy;
CCoinsViewCache view(&dummy);
CAmount nValueIn = 0;
LockPoints lp;
{
LOCK(pool.cs);
CCoinsViewMemPool viewMemPool(pcoinsTip, pool);
view.SetBackend(viewMemPool);
// do all inputs exist?
for (const CTxIn txin : tx.vin) {
if (!pcoinsTip->HaveCoinInCache(txin.prevout)) {
coins_to_uncache.push_back(txin.prevout);
}
if (!view.HaveCoin(txin.prevout)) {
// Are inputs missing because we already have the tx?
for (size_t out = 0; out < tx.vout.size(); out++) {
// Optimistically just do efficient check of cache for outputs
if (pcoinsTip->HaveCoinInCache(COutPoint(hash, out))) {
return state.Invalid(false, REJECT_DUPLICATE, "txn-already-known");
}
}
// Otherwise assume this might be an orphan tx for which we just haven't seen parents yet
if (pfMissingInputs) {
*pfMissingInputs = true;
}
return false; // fMissingInputs and !state.IsInvalid() is used to detect this condition, don't set state.Invalid()
}
}
// Bring the best block into scope
view.GetBestBlock();
nValueIn = view.GetValueIn(tx);
// we have all inputs cached now, so switch back to dummy, so we don't need to keep lock on mempool
view.SetBackend(dummy);
// Only accept BIP68 sequence locked transactions that can be mined in the next
// block; we don't want our mempool filled up with transactions that can't
// be mined yet.
// Must keep pool.cs for this unless we change CheckSequenceLocks to take a
// CoinsViewCache instead of create its own
if (!CheckSequenceLocks(tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp))
return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
}
// Check for non-standard pay-to-script-hash in inputs
if (fRequireStandard && !AreInputsStandard(tx, view))
return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
// Check for non-standard witness in P2WSH
if (tx.HasWitness() && fRequireStandard && !IsWitnessStandard(tx, view))
return state.DoS(0, false, REJECT_NONSTANDARD, "bad-witness-nonstandard", true);
int64_t nSigOpsCost = GetTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
CAmount nValueOut = tx.GetValueOut();
CAmount nFees = nValueIn-nValueOut;
// nModifiedFees includes any fee deltas from PrioritiseTransaction
CAmount nModifiedFees = nFees;
pool.ApplyDelta(hash, nModifiedFees);
// Keep track of transactions that spend a coinbase, which we re-scan
// during reorgs to ensure COINBASE_MATURITY is still met.
bool fSpendsCoinbase = false;
for (const CTxIn &txin : tx.vin) {
const Coin &coin = view.AccessCoin(txin.prevout);
if (coin.IsCoinBase()) {
fSpendsCoinbase = true;
break;
}
}
CTxMemPoolEntry entry(ptx, nFees, nAcceptTime, chainActive.Height(),
fSpendsCoinbase, nSigOpsCost, lp);
unsigned int nSize = entry.GetTxSize();
// Check that the transaction doesn't have an excessive number of
// sigops, making it impossible to mine. Since the coinbase transaction
// itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
// MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
// merely non-standard transaction.
if (nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST)
return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
strprintf("%d", nSigOpsCost));
CAmount mempoolRejectFee = pool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
if (!bypass_limits && mempoolRejectFee > 0 && nModifiedFees < mempoolRejectFee) {
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met", false, strprintf("%d < %d", nFees, mempoolRejectFee));
}
// No transactions are allowed below minRelayTxFee except from disconnected blocks
if (!bypass_limits && nModifiedFees < ::minRelayTxFee.GetFee(nSize)) {
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "min relay fee not met");
}
if (nAbsurdFee && nFees > nAbsurdFee)
return state.Invalid(false,
REJECT_HIGHFEE, "absurdly-high-fee",
strprintf("%d > %d", nFees, nAbsurdFee));
// Calculate in-mempool ancestors, up to a limit.
CTxMemPool::setEntries setAncestors;
size_t nLimitAncestors = gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
size_t nLimitAncestorSize = gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
size_t nLimitDescendants = gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
size_t nLimitDescendantSize = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
std::string errString;
if (!pool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
return state.DoS(0, false, REJECT_NONSTANDARD, "too-long-mempool-chain", false, errString);
}
// A transaction that spends outputs that would be replaced by it is invalid. Now
// that we have the set of all ancestors we can detect this
// pathological case by making sure setConflicts and setAncestors don't
// intersect.
for (CTxMemPool::txiter ancestorIt : setAncestors)
{
const uint256 &hashAncestor = ancestorIt->GetTx().GetHash();
if (setConflicts.count(hashAncestor))
{
return state.DoS(10, false,
REJECT_INVALID, "bad-txns-spends-conflicting-tx", false,
strprintf("%s spends conflicting transaction %s",
hash.ToString(),
hashAncestor.ToString()));
}
}
// Check if it's economically rational to mine this transaction rather
// than the ones it replaces.
CAmount nConflictingFees = 0;
size_t nConflictingSize = 0;
uint64_t nConflictingCount = 0;
CTxMemPool::setEntries allConflicting;
// If we don't hold the lock allConflicting might be incomplete; the
// subsequent RemoveStaged() and addUnchecked() calls don't guarantee
// mempool consistency for us.
LOCK(pool.cs);
const bool fReplacementTransaction = setConflicts.size();
if (fReplacementTransaction)
{
CFeeRate newFeeRate(nModifiedFees, nSize);
std::set<uint256> setConflictsParents;
const int maxDescendantsToVisit = 100;
CTxMemPool::setEntries setIterConflicting;
for (const uint256 &hashConflicting : setConflicts)
{
CTxMemPool::txiter mi = pool.mapTx.find(hashConflicting);
if (mi == pool.mapTx.end())
continue;
// Save these to avoid repeated lookups
setIterConflicting.insert(mi);
// Don't allow the replacement to reduce the feerate of the
// mempool.
//
// We usually don't want to accept replacements with lower
// feerates than what they replaced as that would lower the
// feerate of the next block. Requiring that the feerate always
// be increased is also an easy-to-reason about way to prevent
// DoS attacks via replacements.
//
// The mining code doesn't (currently) take children into
// account (CPFP) so we only consider the feerates of
// transactions being directly replaced, not their indirect
// descendants. While that does mean high feerate children are
// ignored when deciding whether or not to replace, we do
// require the replacement to pay more overall fees too,
// mitigating most cases.
CFeeRate oldFeeRate(mi->GetModifiedFee(), mi->GetTxSize());
if (newFeeRate <= oldFeeRate)
{
return state.DoS(0, false,
REJECT_INSUFFICIENTFEE, "insufficient fee", false,
strprintf("rejecting replacement %s; new feerate %s <= old feerate %s",
hash.ToString(),
newFeeRate.ToString(),
oldFeeRate.ToString()));
}
for (const CTxIn &txin : mi->GetTx().vin)
{
setConflictsParents.insert(txin.prevout.hash);
}
nConflictingCount += mi->GetCountWithDescendants();
}
// This potentially overestimates the number of actual descendants
// but we just want to be conservative to avoid doing too much
// work.
if (nConflictingCount <= maxDescendantsToVisit) {
// If not too many to replace, then calculate the set of
// transactions that would have to be evicted
for (CTxMemPool::txiter it : setIterConflicting) {
pool.CalculateDescendants(it, allConflicting);
}
for (CTxMemPool::txiter it : allConflicting) {
nConflictingFees += it->GetModifiedFee();
nConflictingSize += it->GetTxSize();
}
} else {
return state.DoS(0, false,
REJECT_NONSTANDARD, "too many potential replacements", false,
strprintf("rejecting replacement %s; too many potential replacements (%d > %d)\n",
hash.ToString(),
nConflictingCount,
maxDescendantsToVisit));
}
for (unsigned int j = 0; j < tx.vin.size(); j++)
{
// We don't want to accept replacements that require low
// feerate junk to be mined first. Ideally we'd keep track of
// the ancestor feerates and make the decision based on that,
// but for now requiring all new inputs to be confirmed works.
if (!setConflictsParents.count(tx.vin[j].prevout.hash))
{
// Rather than check the UTXO set - potentially expensive -
// it's cheaper to just check if the new input refers to a
// tx that's in the mempool.
if (pool.mapTx.find(tx.vin[j].prevout.hash) != pool.mapTx.end())
return state.DoS(0, false,
REJECT_NONSTANDARD, "replacement-adds-unconfirmed", false,
strprintf("replacement %s adds unconfirmed input, idx %d",
hash.ToString(), j));
}
}
// The replacement must pay greater fees than the transactions it
// replaces - if we did the bandwidth used by those conflicting
// transactions would not be paid for.
if (nModifiedFees < nConflictingFees)
{
return state.DoS(0, false,
REJECT_INSUFFICIENTFEE, "insufficient fee", false,
strprintf("rejecting replacement %s, less fees than conflicting txs; %s < %s",
hash.ToString(), FormatMoney(nModifiedFees), FormatMoney(nConflictingFees)));
}
// Finally in addition to paying more fees than the conflicts the
// new transaction must pay for its own bandwidth.
CAmount nDeltaFees = nModifiedFees - nConflictingFees;
if (nDeltaFees < ::incrementalRelayFee.GetFee(nSize))
{
return state.DoS(0, false,
REJECT_INSUFFICIENTFEE, "insufficient fee", false,
strprintf("rejecting replacement %s, not enough additional fees to relay; %s < %s",
hash.ToString(),
FormatMoney(nDeltaFees),
FormatMoney(::incrementalRelayFee.GetFee(nSize))));
}
}
unsigned int scriptVerifyFlags = STANDARD_SCRIPT_VERIFY_FLAGS;
if (!chainparams.RequireStandard()) {
scriptVerifyFlags = gArgs.GetArg("-promiscuousmempoolflags", scriptVerifyFlags);
}
// Check against previous transactions
// This is done last to help prevent CPU exhaustion denial-of-service attacks.
PrecomputedTransactionData txdata(tx);
if (!CheckInputs(tx, state, view, true, scriptVerifyFlags, true, false, txdata)) {
// SCRIPT_VERIFY_CLEANSTACK requires SCRIPT_VERIFY_WITNESS, so we
// need to turn both off, and compare against just turning off CLEANSTACK
// to see if the failure is specifically due to witness validation.
CValidationState stateDummy; // Want reported failures to be from first CheckInputs
if (!tx.HasWitness() && CheckInputs(tx, stateDummy, view, true, scriptVerifyFlags & ~(SCRIPT_VERIFY_WITNESS | SCRIPT_VERIFY_CLEANSTACK), true, false, txdata) &&
!CheckInputs(tx, stateDummy, view, true, scriptVerifyFlags & ~SCRIPT_VERIFY_CLEANSTACK, true, false, txdata)) {
// Only the witness is missing, so the transaction itself may be fine.
state.SetCorruptionPossible();
}
return false; // state filled in by CheckInputs
}
// Check again against the current block tip's script verification
// flags to cache our script execution flags. This is, of course,
// useless if the next block has different script flags from the
// previous one, but because the cache tracks script flags for us it
// will auto-invalidate and we'll just have a few blocks of extra
// misses on soft-fork activation.
//
// This is also useful in case of bugs in the standard flags that cause
// transactions to pass as valid when they're actually invalid. For
// instance the STRICTENC flag was incorrectly allowing certain
// CHECKSIG NOT scripts to pass, even though they were invalid.
//
// There is a similar check in CreateNewBlock() to prevent creating
// invalid blocks (using TestBlockValidity), however allowing such
// transactions into the mempool can be exploited as a DoS attack.
unsigned int currentBlockScriptVerifyFlags = GetBlockScriptFlags(chainActive.Tip(), Params().GetConsensus());
if (!CheckInputsFromMempoolAndCache(tx, state, view, pool, currentBlockScriptVerifyFlags, true, txdata))
{
// If we're using promiscuousmempoolflags, we may hit this normally
// Check if current block has some flags that scriptVerifyFlags
// does not before printing an ominous warning
if (!(~scriptVerifyFlags & currentBlockScriptVerifyFlags)) {
return error("%s: BUG! PLEASE REPORT THIS! ConnectInputs failed against latest-block but not STANDARD flags %s, %s",
__func__, hash.ToString(), FormatStateMessage(state));
} else {
if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true, false, txdata)) {
return error("%s: ConnectInputs failed against MANDATORY but not STANDARD flags due to promiscuous mempool %s, %s",
__func__, hash.ToString(), FormatStateMessage(state));
} else {
LogPrintf("Warning: -promiscuousmempool flags set to not include currently enforced soft forks, this may break mining or otherwise cause instability!\n");
}
}
}
// Remove conflicting transactions from the mempool
for (const CTxMemPool::txiter it : allConflicting)
{
LogPrint(BCLog::MEMPOOL, "replacing tx %s with %s for %s BTC additional fees, %d delta bytes\n",
it->GetTx().GetHash().ToString(),
hash.ToString(),
FormatMoney(nModifiedFees - nConflictingFees),
(int)nSize - (int)nConflictingSize);
if (plTxnReplaced)
plTxnReplaced->push_back(it->GetSharedTx());
}
pool.RemoveStaged(allConflicting, false, MemPoolRemovalReason::REPLACED);
// This transaction should only count for fee estimation if:
// - it isn't a BIP 125 replacement transaction (may not be widely supported)
// - it's not being readded during a reorg which bypasses typical mempool fee limits
// - the node is not behind
// - the transaction is not dependent on any other transactions in the mempool
bool validForFeeEstimation = !fReplacementTransaction && !bypass_limits && IsCurrentForFeeEstimation() && pool.HasNoInputsOf(tx);
// Store transaction in memory
pool.addUnchecked(hash, entry, setAncestors, validForFeeEstimation);
// trim mempool and check if tx was trimmed
if (!bypass_limits) {
LimitMempoolSize(pool, gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
if (!pool.exists(hash))
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool full");
}
}
GetMainSignals().TransactionAddedToMempool(ptx);
return true;
}
/** (try to) add transaction to memory pool with a specified acceptance time **/
static bool AcceptToMemoryPoolWithTime(const CChainParams& chainparams, CTxMemPool& pool, CValidationState &state, const CTransactionRef &tx,
bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
bool bypass_limits, const CAmount nAbsurdFee)
{
std::vector<COutPoint> coins_to_uncache;
bool res = AcceptToMemoryPoolWorker(chainparams, pool, state, tx, pfMissingInputs, nAcceptTime, plTxnReplaced, bypass_limits, nAbsurdFee, coins_to_uncache);
if (!res) {
for (const COutPoint& hashTx : coins_to_uncache)
pcoinsTip->Uncache(hashTx);
}
// After we've (potentially) uncached entries, ensure our coins cache is still within its size limits
CValidationState stateDummy;
FlushStateToDisk(chainparams, stateDummy, FLUSH_STATE_PERIODIC);
return res;
}
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransactionRef &tx,
bool* pfMissingInputs, std::list<CTransactionRef>* plTxnReplaced,
bool bypass_limits, const CAmount nAbsurdFee)
{
const CChainParams& chainparams = Params();
return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, pfMissingInputs, GetTime(), plTxnReplaced, bypass_limits, nAbsurdFee);
}
/** Return transaction in txOut, and if it was found inside a block, its hash is placed in hashBlock */
bool GetTransaction(const uint256 &hash, CTransactionRef &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock, bool fAllowSlow)
{
CBlockIndex *pindexSlow = nullptr;
LOCK(cs_main);
CTransactionRef ptx = mempool.get(hash);
if (ptx)
{
txOut = ptx;
return true;
}
if (fTxIndex) {
CDiskTxPos postx;
if (pblocktree->ReadTxIndex(hash, postx)) {
CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
if (file.IsNull())
return error("%s: OpenBlockFile failed", __func__);
CBlockHeader header;
try {
file >> header;
fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
file >> txOut;
} catch (const std::exception& e) {
return error("%s: Deserialize or I/O error - %s", __func__, e.what());
}
hashBlock = header.GetHash();
if (txOut->GetHash() != hash)
return error("%s: txid mismatch", __func__);
return true;
}
}
if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
const Coin& coin = AccessByTxid(*pcoinsTip, hash);
if (!coin.IsSpent()) pindexSlow = chainActive[coin.nHeight];
}
if (pindexSlow) {
CBlock block;
if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
for (const auto& tx : block.vtx) {
if (tx->GetHash() == hash) {
txOut = tx;
hashBlock = pindexSlow->GetBlockHash();
return true;
}
}
}
}
return false;
}
//////////////////////////////////////////////////////////////////////////////
//
// CBlock and CBlockIndex
//
static bool WriteBlockToDisk(const CBlock& block, CDiskBlockPos& pos, const CMessageHeader::MessageStartChars& messageStart)
{
// Open history file to append
CAutoFile fileout(OpenBlockFile(pos), SER_DISK, CLIENT_VERSION);
if (fileout.IsNull())
return error("WriteBlockToDisk: OpenBlockFile failed");
// Write index header
unsigned int nSize = GetSerializeSize(fileout, block);
fileout << FLATDATA(messageStart) << nSize;
// Write block
long fileOutPos = ftell(fileout.Get());
if (fileOutPos < 0)
return error("WriteBlockToDisk: ftell failed");
pos.nPos = (unsigned int)fileOutPos;
fileout << block;
return true;
}
bool ReadBlockFromDisk(CBlock& block, const CDiskBlockPos& pos, const Consensus::Params& consensusParams)
{
block.SetNull();
// Open history file to read
CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);