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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
#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."
* Global state
CCriticalSection cs_main;
BlockMap mapBlockIndex;
CChain chainActive;
CBlockIndex *pindexBestHeader = NULL;
CWaitableCriticalSection csBestBlock;
CConditionVariable cvBlockChange;
int nScriptCheckThreads = 0;
std::atomic_bool fImporting(false);
bool fReindex = false;
bool fTxIndex = false;
bool fHavePruned = false;
bool fPruneMode = false;
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;
CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
CBlockPolicyEstimator feeEstimator;
CTxMemPool mempool(&feeEstimator);
static void CheckBlockIndex(const Consensus::Params& consensusParams);
/** Constant stuff for coinbase transactions we create: */
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 = NULL;
CCoinsViewCache *pcoinsTip = NULL;
CBlockTreeDB *pblocktree = NULL;
enum FlushStateMode {
// 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)
// 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 will require 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)
// 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)
CBlockIndex* tip = chainActive.Tip();
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) {
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;
for (size_t txinIndex = 0; txinIndex <; txinIndex++) {
const CTxIn& txin =[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)
/** Convert CValidationState to a human-readable message for logging */
std::string FormatStateMessage(const CValidationState &state)
return strprintf("%s%s (code %i)",
state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage(),
static bool IsCurrentForFeeEstimation()
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)
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, false, NULL, NULL, true)) {
// 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())) {
// 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.
// 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, GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, 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) {
// 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
for (const CTxIn& txin : {
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.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 fLimitFree,
bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
bool fOverrideMempoolLimit, const CAmount& nAbsurdFee, std::vector<COutPoint>& coins_to_uncache)
const CTransaction& tx = *ptx;
const uint256 hash = tx.GetHash();
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 (!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.
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 :
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;
if (fReplacementOptOut) {
return state.Invalid(false, REJECT_DUPLICATE, "txn-mempool-conflict");
CCoinsView dummy;
CCoinsViewCache view(&dummy);
CAmount nValueIn = 0;
LockPoints lp;
CCoinsViewMemPool viewMemPool(pcoinsTip, pool);
// do all inputs exist?
for (const CTxIn txin : {
if (!pcoinsTip->HaveCoinInCache(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
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
// 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 : {
const Coin &coin = view.AccessCoin(txin.prevout);
if (coin.IsCoinBase()) {
fSpendsCoinbase = true;
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.
return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
strprintf("%d", nSigOpsCost));
CAmount mempoolRejectFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
if (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 (fLimitFree && 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 = GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
size_t nLimitAncestorSize = GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
size_t nLimitDescendants = GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
size_t nLimitDescendantSize = 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",
// 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.
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())
// Save these to avoid repeated lookups
// 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",
for (const CTxIn &txin : mi->GetTx().vin)
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",
for (unsigned int j = 0; j <; 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([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([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",
unsigned int scriptVerifyFlags = STANDARD_SCRIPT_VERIFY_FLAGS;
if (!chainparams.RequireStandard()) {
scriptVerifyFlags = 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)) {
// 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.
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",
FormatMoney(nModifiedFees - nConflictingFees),
(int)nSize - (int)nConflictingSize);
if (plTxnReplaced)
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), the
// node is not behind, and the transaction is not dependent on any other
// transactions in the mempool.
bool validForFeeEstimation = !fReplacementTransaction && IsCurrentForFeeEstimation() && pool.HasNoInputsOf(tx);
// Store transaction in memory
pool.addUnchecked(hash, entry, setAncestors, validForFeeEstimation);
// trim mempool and check if tx was trimmed
if (!fOverrideMempoolLimit) {
LimitMempoolSize(pool, GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
if (!pool.exists(hash))
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool full");
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 fLimitFree,
bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
bool fOverrideMempoolLimit, const CAmount nAbsurdFee)
std::vector<COutPoint> coins_to_uncache;
bool res = AcceptToMemoryPoolWorker(chainparams, pool, state, tx, fLimitFree, pfMissingInputs, nAcceptTime, plTxnReplaced, fOverrideMempoolLimit, nAbsurdFee, coins_to_uncache);
if (!res) {
for (const COutPoint& hashTx : coins_to_uncache)
// 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 fLimitFree,
bool* pfMissingInputs, std::list<CTransactionRef>* plTxnReplaced,
bool fOverrideMempoolLimit, const CAmount nAbsurdFee)
const CChainParams& chainparams = Params();
return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, fLimitFree, pfMissingInputs, GetTime(), plTxnReplaced, fOverrideMempoolLimit, 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 = NULL;
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)
// Open history file to read
CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
if (filein.IsNull())
return error("ReadBlockFromDisk: OpenBlockFile failed for %s", pos.ToString());
// Read block
try {
filein >> block;
catch (const std::exception& e) {
return error("%s: Deserialize or I/O error - %s at %s", __func__, e.what(), pos.ToString());
// Check the header
if (!CheckProofOfWork(block.GetHash(), block.nBits, consensusParams))
return error("ReadBlockFromDisk: Errors in block header at %s", pos.ToString());
return true;
bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex, const Consensus::Params& consensusParams)
if (!ReadBlockFromDisk(block, pindex->GetBlockPos(), consensusParams))
return false;
if (block.GetHash() != pindex->GetBlockHash())
return error("ReadBlockFromDisk(CBlock&, CBlockIndex*): GetHash() doesn't match index for %s at %s",
pindex->ToString(), pindex->GetBlockPos().ToString());
return true;
CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams)
int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
// Force block reward to zero when right shift is undefined.
if (halvings >= 64)
return 0;
CAmount nSubsidy = 50 * COIN;
// Subsidy is cut in half every 210,000 blocks which will occur approximately every 4 years.
nSubsidy >>= halvings;
return nSubsidy;
bool IsInitialBlockDownload()
const CChainParams& chainParams = Params();
// Once this function has returned false, it must remain false.
static std::atomic<bool> latchToFalse{false};
// Optimization: pre-test latch before taking the lock.
if (latchToFalse.load(std::memory_order_relaxed))
return false;
if (latchToFalse.load(std::memory_order_relaxed))
return false;
if (fImporting || fReindex)
return true;
if (chainActive.Tip() == NULL)
return true;
if (chainActive.Tip()->nChainWork < UintToArith256(chainParams.GetConsensus().nMinimumChainWork))
return true;
if (chainActive.Tip()->GetBlockTime() < (GetTime() - nMaxTipAge))
return true;
LogPrintf("Leaving InitialBlockDownload (latching to false)\n");, std::memory_order_relaxed);
return false;
CBlockIndex *pindexBestForkTip = NULL, *pindexBestForkBase = NULL;
static void AlertNotify(const std::string& strMessage)
std::string strCmd = GetArg("-alertnotify", "");
if (strCmd.empty()) return;
// Alert text should be plain ascii coming from a trusted source, but to
// be safe we first strip anything not in safeChars, then add single quotes around
// the whole string before passing it to the shell:
std::string singleQuote("'");
std::string safeStatus = SanitizeString(strMessage);
safeStatus = singleQuote+safeStatus+singleQuote;
boost::replace_all(strCmd, "%s", safeStatus);
boost::thread t(runCommand, strCmd); // thread runs free
static void CheckForkWarningConditions()
// Before we get past initial download, we cannot reliably alert about forks
// (we assume we don't get stuck on a fork before finishing our initial sync)
if (IsInitialBlockDownload())
// If our best fork is no longer within 72 blocks (+/- 12 hours if no one mines it)
// of our head, drop it
if (pindexBestForkTip && chainActive.Height() - pindexBestForkTip->nHeight >= 72)
pindexBestForkTip = NULL;
if (pindexBestForkTip || (pindexBestInvalid && pindexBestInvalid->nChainWork > chainActive.Tip()->nChainWork + (GetBlockProof(*chainActive.Tip()) * 6)))
if (!GetfLargeWorkForkFound() && pindexBestForkBase)
std::string warning = std::string("'Warning: Large-work fork detected, forking after block ") +
pindexBestForkBase->phashBlock->ToString() + std::string("'");
if (pindexBestForkTip && pindexBestForkBase)
LogPrintf("%s: Warning: Large valid fork found\n forking the chain at height %d (%s)\n lasting to height %d (%s).\nChain state database corruption likely.\n", __func__,
pindexBestForkBase->nHeight, pindexBestForkBase->phashBlock->ToString(),
pindexBestForkTip->nHeight, pindexBestForkTip->phashBlock->ToString());
LogPrintf("%s: Warning: Found invalid chain at least ~6 blocks longer than our best chain.\nChain state database corruption likely.\n", __func__);
static void CheckForkWarningConditionsOnNewFork(CBlockIndex* pindexNewForkTip)
// If we are on a fork that is sufficiently large, set a warning flag
CBlockIndex* pfork = pindexNewForkTip;
CBlockIndex* plonger = chainActive.Tip();
while (pfork && pfork != plonger)
while (plonger && plonger->nHeight > pfork->nHeight)
plonger = plonger->pprev;
if (pfork == plonger)
pfork = pfork->pprev;
// We define a condition where we should warn the user about as a fork of at least 7 blocks
// with a tip within 72 blocks (+/- 12 hours if no one mines it) of ours
// We use 7 blocks rather arbitrarily as it represents just under 10% of sustained network
// hash rate operating on the fork.
// or a chain that is entirely longer than ours and invalid (note that this should be detected by both)
// We define it this way because it allows us to only store the highest fork tip (+ base) which meets
// the 7-block condition and from this always have the most-likely-to-cause-warning fork
if (pfork && (!pindexBestForkTip || pindexNewForkTip->nHeight > pindexBestForkTip->nHeight) &&
pindexNewForkTip->nChainWork - pfork->nChainWork > (GetBlockProof(*pfork) * 7) &&
chainActive.Height() - pindexNewForkTip->nHeight < 72)
pindexBestForkTip = pindexNewForkTip;
pindexBestForkBase = pfork;
void static InvalidChainFound(CBlockIndex* pindexNew)
if (!pindexBestInvalid || pindexNew->nChainWork > pindexBestInvalid->nChainWork)
pindexBestInvalid = pindexNew;
LogPrintf("%s: invalid block=%s height=%d log2_work=%.8g date=%s\n", __func__,
pindexNew->GetBlockHash().ToString(), pindexNew->nHeight,
log(pindexNew->nChainWork.getdouble())/log(2.0), DateTimeStrFormat("%Y-%m-%d %H:%M:%S",
CBlockIndex *tip = chainActive.Tip();
assert (tip);
LogPrintf("%s: current best=%s height=%d log2_work=%.8g date=%s\n", __func__,
tip->GetBlockHash().ToString(), chainActive.Height(), log(tip->nChainWork.getdouble())/log(2.0),
DateTimeStrFormat("%Y-%m-%d %H:%M:%S", tip->GetBlockTime()));
void static InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
if (!state.CorruptionPossible()) {
pindex->nStatus |= BLOCK_FAILED_VALID;
void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, CTxUndo &txundo, int nHeight)
// mark inputs spent
if (!tx.IsCoinBase()) {
for (const CTxIn &txin : {
bool is_spent = inputs.SpendCoin(txin.prevout, &txundo.vprevout.back());
// add outputs
AddCoins(inputs, tx, nHeight);
void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight)
CTxUndo txundo;
UpdateCoins(tx, inputs, txundo, nHeight);
bool CScriptCheck::operator()() {
const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
const CScriptWitness *witness = &ptxTo->vin[nIn].scriptWitness;
return VerifyScript(scriptSig, scriptPubKey, witness, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, amount, cacheStore, *txdata), &error);
int GetSpendHeight(const CCoinsViewCache& inputs)
CBlockIndex* pindexPrev = mapBlockIndex.find(inputs.GetBestBlock())->second;
return pindexPrev->nHeight + 1;
static CuckooCache::cache<uint256, SignatureCacheHasher> scriptExecutionCache;
static uint256 scriptExecutionCacheNonce(GetRandHash());
void InitScriptExecutionCache() {
// nMaxCacheSize is unsigned. If -maxsigcachesize is set to zero,
// setup_bytes creates the minimum possible cache (2 elements).
size_t nMaxCacheSize = std::min(std::max((int64_t)0, GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) / 2), MAX_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20);
size_t nElems = scriptExecutionCache.setup_bytes(nMaxCacheSize);
LogPrintf("Using %zu MiB out of %zu/2 requested for script execution cache, able to store %zu elements\n",
(nElems*sizeof(uint256)) >>20, (nMaxCacheSize*2)>>20, nElems);
* Check whether all inputs of this transaction are valid (no double spends, scripts & sigs, amounts)
* This does not modify the UTXO set.
* If pvChecks is not NULL, script checks are pushed onto it instead of being performed inline. Any
* script checks which are not necessary (eg due to script execution cache hits) are, obviously,
* not pushed onto pvChecks/run.
* Setting cacheSigStore/cacheFullScriptStore to false will remove elements from the corresponding cache
* which are matched. This is useful for checking blocks where we will likely never need the cache
* entry again.
* Non-static (and re-declared) in src/test/txvalidationcache_tests.cpp
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)
if (!tx.IsCoinBase())
if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs)))
return false;
if (pvChecks)
// The first loop above does all the inexpensive checks.
// Only if ALL inputs pass do we perform expensive ECDSA signature checks.
// Helps prevent CPU exhaustion attacks.
// Skip script verification when connecting blocks under the
// assumevalid block. Assuming the assumevalid block is valid this
// is safe because block merkle hashes are still computed and checked,
// Of course, if an assumed valid block is invalid due to false scriptSigs
// this optimization would allow an invalid chain to be accepted.
if (fScriptChecks) {
// First check if script executions have been cached with the same
// flags. Note that this assumes that the inputs provided are
// correct (ie that the transaction hash which is in tx's prevouts
// properly commits to the scriptPubKey in the inputs view of that
// transaction).
uint256 hashCacheEntry;
// We only use the first 19 bytes of nonce to avoid a second SHA
// round - giving us 19 + 32 + 4 = 55 bytes (+ 8 + 1 = 64)
static_assert(55 - sizeof(flags) - 32 >= 128/8, "Want at least 128 bits of nonce for script execution cache");
CSHA256().Write(scriptExecutionCacheNonce.begin(), 55 - sizeof(flags) - 32).Write(tx.GetWitnessHash().begin(), 32).Write((unsigned char*)&flags, sizeof(flags)).Finalize(hashCacheEntry.begin());
AssertLockHeld(cs_main); //TODO: Remove this requirement by making CuckooCache not require external locks
if (scriptExecutionCache.contains(hashCacheEntry, !cacheFullScriptStore)) {
return true;
for (unsigned int i = 0; i <; i++) {
const COutPoint &prevout =[i].prevout;
const Coin& coin = inputs.AccessCoin(prevout);
// We very carefully only pass in things to CScriptCheck which
// are clearly committed to by tx' witness hash. This provides
// a sanity check that our caching is not introducing consensus
// failures through additional data in, eg, the coins being
// spent being checked as a part of CScriptCheck.
const CScript& scriptPubKey = coin.out.scriptPubKey;
const CAmount amount = coin.out.nValue;
// Verify signature
CScriptCheck check(scriptPubKey, amount, tx, i, flags, cacheSigStore, &txdata);
if (pvChecks) {
} else if (!check()) {
// Check whether the failure was caused by a
// non-mandatory script verification check, such as
// non-standard DER encodings or non-null dummy
// arguments; if so, don't trigger DoS protection to
// avoid splitting the network between upgraded and
// non-upgraded nodes.
CScriptCheck check2(scriptPubKey, amount, tx, i,
flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheSigStore, &txdata);
if (check2())
return state.Invalid(false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError())));
// Failures of other flags indicate a transaction that is
// invalid in new blocks, e.g. an invalid P2SH. We DoS ban
// such nodes as they are not following the protocol. That
// said during an upgrade careful thought should be taken
// as to the correct behavior - we may want to continue
// peering with non-upgraded nodes even after soft-fork
// super-majority signaling has occurred.
return state.DoS(100,false, REJECT_INVALID, strprintf("mandatory-script-verify-flag-failed (%s)", ScriptErrorString(check.GetScriptError())));
if (cacheFullScriptStore && !pvChecks) {
// We executed all of the provided scripts, and were told to
// cache the result. Do so now.
return true;
namespace {
bool UndoWriteToDisk(const CBlockUndo& blockundo, CDiskBlockPos& pos, const uint256& hashBlock, const CMessageHeader::MessageStartChars& messageStart)
// Open history file to append
CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
if (fileout.IsNull())
return error("%s: OpenUndoFile failed", __func__);
// Write index header
unsigned int nSize = GetSerializeSize(fileout, blockundo);
fileout << FLATDATA(messageStart) << nSize;
// Write undo data
long fileOutPos = ftell(fileout.Get());
if (fileOutPos < 0)
return error("%s: ftell failed", __func__);
pos.nPos = (unsigned int)fileOutPos;
fileout << blockundo;
// calculate & write checksum
hasher << hashBlock;
hasher << blockundo;
fileout << hasher.GetHash();
return true;
bool UndoReadFromDisk(CBlockUndo& blockundo, const CDiskBlockPos& pos, const uint256& hashBlock)
// Open history file to read
CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
if (filein.IsNull())
return error("%s: OpenUndoFile failed", __func__);
// Read block
uint256 hashChecksum;
CHashVerifier<CAutoFile> verifier(&filein); // We need a CHashVerifier as reserializing may lose data
try {
verifier << hashBlock;
verifier >> blockundo;
filein >> hashChecksum;
catch (const std::exception& e) {
return error("%s: Deserialize or I/O error - %s", __func__, e.what());
// Verify checksum
if (hashChecksum != verifier.GetHash())
return error("%s: Checksum mismatch", __func__);
return true;
/** Abort with a message */
bool AbortNode(const std::string& strMessage, const std::string& userMessage="")
LogPrintf("*** %s\n", strMessage);
userMessage.empty() ? _("Error: A fatal internal error occurred, see debug.log for details") : userMessage,
"", CClientUIInterface::MSG_ERROR);
return false;
bool AbortNode(CValidationState& state, const std::string& strMessage, const std::string& userMessage="")
AbortNode(strMessage, userMessage);
return state.Error(strMessage);
} // namespace
enum DisconnectResult
DISCONNECT_OK, // All good.
DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
DISCONNECT_FAILED // Something else went wrong.
* Restore the UTXO in a Coin at a given COutPoint
* @param undo The Coin to be restored.
* @param view The coins view to which to apply the changes.
* @param out The out point that corresponds to the tx input.
* @return A DisconnectResult as an int
int ApplyTxInUndo(Coin&& undo, CCoinsViewCache& view, const COutPoint& out)
bool fClean = true;
if (view.HaveCoin(out)) fClean = false; // overwriting transaction output
if (undo.nHeight == 0) {
// Missing undo metadata (height and coinbase). Older versions included this
// information only in undo records for the last spend of a transactions'
// outputs. This implies that it must be present for some other output of the same tx.
const Coin& alternate = AccessByTxid(view, out.hash);
if (!alternate.IsSpent()) {
undo.nHeight = alternate.nHeight;
undo.fCoinBase = alternate.fCoinBase;
} else {
return DISCONNECT_FAILED; // adding output for transaction without known metadata
// The potential_overwrite parameter to AddCoin is only allowed to be false if we know for
// sure that the coin did not already exist in the cache. As we have queried for that above
// using HaveCoin, we don't need to guess. When fClean is false, a coin already existed and
// it is an overwrite.
view.AddCoin(out, std::move(undo), !fClean);
/** Undo the effects of this block (with given index) on the UTXO set represented by coins.
* When FAILED is returned, view is left in an indeterminate state. */
static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)
bool fClean = true;
CBlockUndo blockUndo;
CDiskBlockPos pos = pindex->GetUndoPos();
if (pos.IsNull()) {
error("DisconnectBlock(): no undo data available");
if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash())) {
error("DisconnectBlock(): failure reading undo data");
if (blockUndo.vtxundo.size() + 1 != block.vtx.size()) {
error("DisconnectBlock(): block and undo data inconsistent");
// undo transactions in reverse order
for (int i = block.vtx.size() - 1; i >= 0; i--) {
const CTransaction &tx = *(block.vtx[i]);
uint256 hash = tx.GetHash();
bool is_coinbase = tx.IsCoinBase();
// Check that all outputs are available and match the outputs in the block itself
// exactly.
for (size_t o = 0; o < tx.vout.size(); o++) {
if (!tx.vout[o].scriptPubKey.IsUnspendable()) {
COutPoint out(hash, o);
Coin coin;
bool is_spent = view.SpendCoin(out, &coin);
if (!is_spent || tx.vout[o] != coin.out || pindex->nHeight != coin.nHeight || is_coinbase != coin.fCoinBase) {
fClean = false; // transaction output mismatch
// restore inputs
if (i > 0) { // not coinbases
CTxUndo &txundo = blockUndo.vtxundo[i-1];
if (txundo.vprevout.size() != {
error("DisconnectBlock(): transaction and undo data inconsistent");
for (unsigned int j =; j-- > 0;) {
const COutPoint &out =[j].prevout;
int res = ApplyTxInUndo(std::move(txundo.vprevout[j]), view, out);
fClean = fClean && res != DISCONNECT_UNCLEAN;
// At this point, all of txundo.vprevout should have been moved out.
// move best block pointer to prevout block
void static FlushBlockFile(bool fFinalize = false)
CDiskBlockPos posOld(nLastBlockFile, 0);
FILE *fileOld = OpenBlockFile(posOld);
if (fileOld) {
if (fFinalize)
TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nSize);
fileOld = OpenUndoFile(posOld);
if (fileOld) {
if (fFinalize)
TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nUndoSize);
static bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
void ThreadScriptCheck() {
// Protected by cs_main
VersionBitsCache versionbitscache;
int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params)
int32_t nVersion = VERSIONBITS_TOP_BITS;
for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; i++) {
ThresholdState state = VersionBitsState(pindexPrev, params, (Consensus::DeploymentPos)i, versionbitscache);
nVersion |= VersionBitsMask(params, (Consensus::DeploymentPos)i);
return nVersion;
* Threshold condition checker that triggers when unknown versionbits are seen on the network.
class WarningBitsConditionChecker : public AbstractThresholdConditionChecker
int bit;
WarningBitsConditionChecker(int bitIn) : bit(bitIn) {}
int64_t BeginTime(const Consensus::Params& params) const override { return 0; }
int64_t EndTime(const Consensus::Params& params) const override { return std::numeric_limits<int64_t>::max(); }
int Period(const Consensus::Params& params) const override { return params.nMinerConfirmationWindow; }
int Threshold(const Consensus::Params& params) const override { return params.nRuleChangeActivationThreshold; }
bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const override
return ((pindex->nVersion & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) &&
((pindex->nVersion >> bit) & 1) != 0 &&
((ComputeBlockVersion(pindex->pprev, params) >> bit) & 1) == 0;
// Protected by cs_main
static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS];
static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& consensusparams) {
// BIP16 didn't become active until Apr 1 2012
int64_t nBIP16SwitchTime = 1333238400;
bool fStrictPayToScriptHash = (pindex->GetBlockTime() >= nBIP16SwitchTime);
unsigned int flags = fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE;
// Start enforcing the DERSIG (BIP66) rule
if (pindex->nHeight >= consensusparams.BIP66Height) {
// Start enforcing CHECKLOCKTIMEVERIFY (BIP65) rule
if (pindex->nHeight >= consensusparams.BIP65Height) {
// Start enforcing BIP68 (sequence locks) and BIP112 (CHECKSEQUENCEVERIFY) using versionbits logic.
if (VersionBitsState(pindex->pprev, consensusparams, Consensus::DEPLOYMENT_CSV, versionbitscache) == THRESHOLD_ACTIVE) {
// Start enforcing WITNESS rules using versionbits logic.
if (IsWitnessEnabled(pindex->pprev, consensusparams)) {
return flags;
static int64_t nTimeCheck = 0;
static int64_t nTimeForks = 0;
static int64_t nTimeVerify = 0;
static int64_t nTimeConnect = 0;
static int64_t nTimeIndex = 0;
static int64_t nTimeCallbacks = 0;
static int64_t nTimeTotal = 0;
/** Apply the effects of this block (with given index) on the UTXO set represented by coins.
* Validity checks that depend on the UTXO set are also done; ConnectBlock()
* can fail if those validity checks fail (among other reasons). */
static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex,
CCoinsViewCache& view, const CChainParams& chainparams, bool fJustCheck = false)
// pindex->phashBlock can be null if called by CreateNewBlock/TestBlockValidity
assert((pindex->phashBlock == NULL) ||
(*pindex->phashBlock == block.GetHash()));
int64_t nTimeStart = GetTimeMicros();
// Check it again in case a previous version let a bad block in
if (!CheckBlock(block, state, chainparams.GetConsensus(), !fJustCheck, !fJustCheck))
return error("%s: Consensus::CheckBlock: %s", __func__, FormatStateMessage(state));
// verify that the view's current state corresponds to the previous block
uint256 hashPrevBlock = pindex->pprev == NULL ? uint256() : pindex->pprev->GetBlockHash();
assert(hashPrevBlock == view.GetBestBlock());
// Special case for the genesis block, skipping connection of its transactions
// (its coinbase is unspendable)
if (block.GetHash() == chainparams.GetConsensus().hashGenesisBlock) {
if (!fJustCheck)
return true;
bool fScriptChecks = true;
if (!hashAssumeValid.IsNull()) {
// We've been configured with the hash of a block which has been externally verified to have a valid history.
// A suitable default value is included with the software and updated from time to time. Because validity
// relative to a piece of software is an objective fact these defaults can be easily reviewed.
// This setting doesn't force the selection of any particular chain but makes validating some faster by
// effectively caching the result of part of the verification.
BlockMap::const_iterator it = mapBlockIndex.find(hashAssumeValid);
if (it != mapBlockIndex.end()) {
if (it->second->GetAncestor(pindex->nHeight) == pindex &&
pindexBestHeader->GetAncestor(pindex->nHeight) == pindex &&
pindexBestHeader->nChainWork >= UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
// This block is a member of the assumed verified chain and an ancestor of the best header.
// The equivalent time check discourages hash power from extorting the network via DOS attack
// into accepting an invalid block through telling users they must manually set assumevalid.
// Requiring a software change or burying the invalid block, regardless of the setting, makes
// it hard to hide the implication of the demand. This also avoids having release candidates
// that are hardly doing any signature verification at all in testing without having to
// artificially set the default assumed verified block further back.
// The test against nMinimumChainWork prevents the skipping when denied access to any chain at
// least as good as the expected chain.
fScriptChecks = (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, chainparams.GetConsensus()) <= 60 * 60 * 24 * 7 * 2);
int64_t nTime1 = GetTimeMicros(); nTimeCheck += nTime1 - nTimeStart;
LogPrint(BCLog::BENCH, " - Sanity checks: %.2fms [%.2fs]\n", 0.001 * (nTime1 - nTimeStart), nTimeCheck * 0.000001);
// Do not allow blocks that contain transactions which 'overwrite' older transactions,
// unless those are already completely spent.
// If such overwrites are allowed, coinbases and transactions depending upon those
// can be duplicated to remove the ability to spend the first instance -- even after
// being sent to another address.
// See BIP30 and for more information.
// This logic is not necessary for memory pool transactions, as AcceptToMemoryPool
// already refuses previously-known transaction ids entirely.
// This rule was originally applied to all blocks with a timestamp after March 15, 2012, 0:00 UTC.
// Now that the whole chain is irreversibly beyond that time it is applied to all blocks except the
// two in the chain that violate it. This prevents exploiting the issue against nodes during their
// initial block download.
bool fEnforceBIP30 = (!pindex->phashBlock) || // Enforce on CreateNewBlock invocations which don't have a hash.
!((pindex->nHeight==91842 && pindex->GetBlockHash() == uint256S("0x00000000000a4d0a398161ffc163c503763b1f4360639393e0e4c8e300e0caec")) ||
(pindex->nHeight==91880 && pindex->GetBlockHash() == uint256S("0x00000000000743f190a18c5577a3c2d2a1f610ae9601ac046a38084ccb7cd721")));
// Once BIP34 activated it was not possible to create new duplicate coinbases and thus other than starting
// with the 2 existing duplicate coinbase pairs, not possible to create overwriting txs. But by the
// time BIP34 activated, in each of the existing pairs the duplicate coinbase had overwritten the first
// before the first had been spent. Since those coinbases are sufficiently buried its no longer possible to create further
// duplicate transactions descending from the known pairs either.
// If we're on the known chain at height greater than where BIP34 activated, we can save the db accesses needed for the BIP30 check.
CBlockIndex *pindexBIP34height = pindex->pprev->GetAncestor(chainparams.GetConsensus().BIP34Height);
//Only continue to enforce if we're below BIP34 activation height or the block hash at that height doesn't correspond.
fEnforceBIP30 = fEnforceBIP30 && (!pindexBIP34height || !(pindexBIP34height->GetBlockHash() == chainparams.GetConsensus().BIP34Hash));
if (fEnforceBIP30) {
for (const auto& tx : block.vtx) {
for (size_t o = 0; o < tx->vout.size(); o++) {
if (view.HaveCoin(COutPoint(tx->GetHash(), o))) {
return state.DoS(100, error("ConnectBlock(): tried to overwrite transaction"),
REJECT_INVALID, "bad-txns-BIP30");
// Start enforcing BIP68 (sequence locks) and BIP112 (CHECKSEQUENCEVERIFY) using versionbits logic.
int nLockTimeFlags = 0;
if (VersionBitsState(pindex->pprev, chainparams.GetConsensus(), Consensus::DEPLOYMENT_CSV, versionbitscache) == THRESHOLD_ACTIVE) {
// Get the script flags for this block
unsigned int flags = GetBlockScriptFlags(pindex, chainparams.GetConsensus());
int64_t nTime2 = GetTimeMicros(); nTimeForks += nTime2 - nTime1;
LogPrint(BCLog::BENCH, " - Fork checks: %.2fms [%.2fs]\n", 0.001 * (nTime2 - nTime1), nTimeForks * 0.000001);
CBlockUndo blockundo;
CCheckQueueControl<CScriptCheck> control(fScriptChecks && nScriptCheckThreads ? &scriptcheckqueue : NULL);
std::vector<int> prevheights;
CAmount nFees = 0;
int nInputs = 0;
int64_t nSigOpsCost = 0;
CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size()));
std::vector<std::pair<uint256, CDiskTxPos> > vPos;
blockundo.vtxundo.reserve(block.vtx.size() - 1);
std::vector<PrecomputedTransactionData> txdata;
txdata.reserve(block.vtx.size()); // Required so that pointers to individual PrecomputedTransactionData don't get invalidated
for (unsigned int i = 0; i < block.vtx.size(); i++)
const CTransaction &tx = *(block.vtx[i]);
nInputs +=;
if (!tx.IsCoinBase())
if (!view.HaveInputs(tx))
return state.DoS(100, error("ConnectBlock(): inputs missing/spent"),
REJECT_INVALID, "bad-txns-inputs-missingorspent");
// Check that transaction is BIP68 final
// BIP68 lock checks (as opposed to nLockTime checks) must
// be in ConnectBlock because they require the UTXO set
for (size_t j = 0; j <; j++) {
prevheights[j] = view.AccessCoin([j].prevout).nHeight;
if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
return state.DoS(100, error("%s: contains a non-BIP68-final transaction", __func__),
REJECT_INVALID, "bad-txns-nonfinal");
// GetTransactionSigOpCost counts 3 types of sigops:
// * legacy (always)
// * p2sh (when P2SH enabled in flags and excludes coinbase)
// * witness (when witness enabled in flags and excludes coinbase)
nSigOpsCost += GetTransactionSigOpCost(tx, view, flags);
return state.DoS(100, error("ConnectBlock(): too many sigops"),
REJECT_INVALID, "bad-blk-sigops");
if (!tx.IsCoinBase())
nFees += view.GetValueIn(tx)-tx.GetValueOut();
std::vector<CScriptCheck> vChecks;
bool fCacheResults = fJustCheck; /* Don't cache results if we're actually connecting blocks (still consult the cache, though) */
if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, fCacheResults, txdata[i], nScriptCheckThreads ? &vChecks : NULL))
return error("ConnectBlock(): CheckInputs on %s failed with %s",
tx.GetHash().ToString(), FormatStateMessage(state));
CTxUndo undoDummy;
if (i > 0) {
UpdateCoins(tx, view, i == 0 ? undoDummy : blockundo.vtxundo.back(), pindex->nHeight);
vPos.push_back(std::make_pair(tx.GetHash(), pos));
pos.nTxOffset += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
int64_t nTime3 = GetTimeMicros(); nTimeConnect += nTime3 - nTime2;
LogPrint(BCLog::BENCH, " - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) [%.2fs]\n", (unsigned)block.vtx.size(), 0.001 * (nTime3 - nTime2), 0.001 * (nTime3 - nTime2) / block.vtx.size(), nInputs <= 1 ? 0 : 0.001 * (nTime3 - nTime2) / (nInputs-1), nTimeConnect * 0.000001);
CAmount blockReward = nFees + GetBlockSubsidy(pindex->nHeight, chainparams.GetConsensus());
if (block.vtx[0]->GetValueOut() > blockReward)
return state.DoS(100,
error("ConnectBlock(): coinbase pays too much (actual=%d vs limit=%d)",
block.vtx[0]->GetValueOut(), blockReward),
REJECT_INVALID, "bad-cb-amount");
if (!control.Wait())
return state.DoS(100, error("%s: CheckQueue failed", __func__), REJECT_INVALID, "block-validation-failed");
int64_t nTime4 = GetTimeMicros(); nTimeVerify += nTime4 - nTime2;
LogPrint(BCLog::BENCH, " - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs]\n", nInputs - 1, 0.001 * (nTime4 - nTime2), nInputs <= 1 ? 0 : 0.001 * (nTime4 - nTime2) / (nInputs-1), nTimeVerify * 0.000001);
if (fJustCheck)
return true;
// Write undo information to disk
if (pindex->GetUndoPos().IsNull() || !pindex->IsValid(BLOCK_VALID_SCRIPTS))
if (pindex->GetUndoPos().IsNull()) {
CDiskBlockPos _pos;
if (!FindUndoPos(state, pindex->nFile, _pos, ::GetSerializeSize(blockundo, SER_DISK, CLIENT_VERSION) + 40))
return error("ConnectBlock(): FindUndoPos failed");
if (!UndoWriteToDisk(blockundo, _pos, pindex->pprev->GetBlockHash(), chainparams.MessageStart()))
return AbortNode(state, "Failed to write undo data");
// update nUndoPos in block index
pindex->nUndoPos = _pos.nPos;
pindex->nStatus |= BLOCK_HAVE_UNDO;
if (fTxIndex)
if (!pblocktree->WriteTxIndex(vPos))
return AbortNode(state, "Failed to write transaction index");
// add this block to the view's block chain
int64_t nTime5 = GetTimeMicros(); nTimeIndex += nTime5 - nTime4;
LogPrint(BCLog::BENCH, " - Index writing: %.2fms [%.2fs]\n", 0.001 * (nTime5 - nTime4), nTimeIndex * 0.000001);
int64_t nTime6 = GetTimeMicros(); nTimeCallbacks += nTime6 - nTime5;
LogPrint(BCLog::BENCH, " - Callbacks: %.2fms [%.2fs]\n", 0.001 * (nTime6 - nTime5), nTimeCallbacks * 0.000001);
return true;
* Update the on-disk chain state.
* The caches and indexes are flushed depending on the mode we're called with
* if they're too large, if it's been a while since the last write,
* or always and in all cases if we're in prune mode and are deleting files.
bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &state, FlushStateMode mode, int nManualPruneHeight) {
int64_t nMempoolUsage = mempool.DynamicMemoryUsage();
static int64_t nLastWrite = 0;
static int64_t nLastFlush = 0;
static int64_t nLastSetChain = 0;
std::set<int> setFilesToPrune;
bool fFlushForPrune = false;
bool fDoFullFlush = false;
int64_t nNow = 0;
try {
if (fPruneMode && (fCheckForPruning || nManualPruneHeight > 0) && !fReindex) {
if (nManualPruneHeight > 0) {
FindFilesToPruneManual(setFilesToPrune, nManualPruneHeight);
} else {
FindFilesToPrune(setFilesToPrune, chainparams.PruneAfterHeight());
fCheckForPruning = false;
if (!setFilesToPrune.empty()) {
fFlushForPrune = true;
if (!fHavePruned) {
pblocktree->WriteFlag("prunedblockfiles", true);
fHavePruned = true;
nNow = GetTimeMicros();
// Avoid writing/flushing immediately after startup.
if (nLastWrite == 0) {
nLastWrite = nNow;
if (nLastFlush == 0) {
nLastFlush = nNow;
if (nLastSetChain == 0) {
nLastSetChain = nNow;
int64_t nMempoolSizeMax = GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
int64_t cacheSize = pcoinsTip->DynamicMemoryUsage();
int64_t nTotalSpace = nCoinCacheUsage + std::max<int64_t>(nMempoolSizeMax - nMempoolUsage, 0);
// The cache is large and we're within 10% and 10 MiB of the limit, but we have time now (not in the middle of a block processing).
bool fCacheLarge = mode == FLUSH_STATE_PERIODIC && cacheSize > std::max((9 * nTotalSpace) / 10, nTotalSpace - MAX_BLOCK_COINSDB_USAGE * 1024 * 1024);
// The cache is over the limit, we have to write now.
bool fCacheCritical = mode == FLUSH_STATE_IF_NEEDED && cacheSize > nTotalSpace;
// It's been a while since we wrote the block index to disk. Do this frequently, so we don't need to redownload after a crash.
bool fPeriodicWrite = mode == FLUSH_STATE_PERIODIC && nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
// It's been very long since we flushed the cache. Do this infrequently, to optimize cache usage.
bool fPeriodicFlush = mode == FLUSH_STATE_PERIODIC && nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
// Combine all conditions that result in a full cache flush.
fDoFullFlush = (mode == FLUSH_STATE_ALWAYS) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
// Write blocks and block index to disk.
if (fDoFullFlush || fPeriodicWrite) {
// Depend on nMinDiskSpace to ensure we can write block index
if (!CheckDiskSpace(0))
return state.Error("out of disk space");
// First make sure all block and undo data is flushed to disk.
// Then update all block file information (which may refer to block and undo files).
std::vector<std::pair<int, const CBlockFileInfo*> > vFiles;
for (std::set<int>::iterator it = setDirtyFileInfo.begin(); it != setDirtyFileInfo.end(); ) {
vFiles.push_back(std::make_pair(*it, &vinfoBlockFile[*it]));
std::vector<const CBlockIndex*> vBlocks;
for (std::set<CBlockIndex*>::iterator it = setDirtyBlockIndex.begin(); it != setDirtyBlockIndex.end(); ) {
if (!pblocktree->WriteBatchSync(vFiles, nLastBlockFile, vBlocks)) {
return AbortNode(state, "Failed to write to block index database");
// Finally remove any pruned files
if (fFlushForPrune)
nLastWrite = nNow;
// Flush best chain related state. This can only be done if the blocks / block index write was also done.
if (fDoFullFlush) {
// Typical Coin structures on disk are around 48 bytes in size.
// Pushing a new one to the database can cause it to be written
// twice (once in the log, and once in the tables). This is already
// an overestimation, as most will delete an existing entry or
// overwrite one. Still, use a conservative safety factor of 2.
if (!CheckDiskSpace(48 * 2 * 2 * pcoinsTip->GetCacheSize()))
return state.Error("out of disk space");
// Flush the chainstate (which may refer to block index entries).
if (!pcoinsTip->Flush())
return AbortNode(state, "Failed to write to coin database");
nLastFlush = nNow;
if (fDoFullFlush || ((mode == FLUSH_STATE_ALWAYS || mode == FLUSH_STATE_PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000)) {
// Update best block in wallet (so we can detect restored wallets).
nLastSetChain = nNow;
} catch (const std::runtime_error& e) {
return AbortNode(state, std::string("System error while flushing: ") + e.what());
return true;
void FlushStateToDisk() {
CValidationState state;
const CChainParams& chainparams = Params();
FlushStateToDisk(chainparams, state, FLUSH_STATE_ALWAYS);
void PruneAndFlush() {
CValidationState state;
fCheckForPruning = true;
const CChainParams& chainparams = Params();
FlushStateToDisk(chainparams, state, FLUSH_STATE_NONE);
static void DoWarning(const std::string& strWarning)
static bool fWarned = false;
if (!fWarned) {
fWarned = true;
/** Update chainActive and related internal data structures. */
void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
// New best block
std::vector<std::string> warningMessages;
if (!IsInitialBlockDownload())
int nUpgraded = 0;
const CBlockIndex* pindex = chainActive.Tip();
for (int bit = 0; bit < VERSIONBITS_NUM_BITS; bit++) {
WarningBitsConditionChecker checker(bit);
ThresholdState state = checker.GetStateFor(pindex, chainParams.GetConsensus(), warningcache[bit]);
if (state == THRESHOLD_ACTIVE || state == THRESHOLD_LOCKED_IN) {
const std::string strWarning = strprintf(_("Warning: unknown new rules activated (versionbit %i)"), bit);
if (state == THRESHOLD_ACTIVE) {
} else {
// Check the version of the last 100 blocks to see if we need to upgrade:
for (int i = 0; i < 100 && pindex != NULL; i++)
int32_t nExpectedVersion = ComputeBlockVersion(pindex->pprev, chainParams.GetConsensus());
if (pindex->nVersion > VERSIONBITS_LAST_OLD_BLOCK_VERSION && (pindex->nVersion & ~nExpectedVersion) != 0)
pindex = pindex->pprev;
if (nUpgraded > 0)
warningMessages.push_back(strprintf(_("%d of last 100 blocks have unexpected version"), nUpgraded));
if (nUpgraded > 100/2)
std::string strWarning = _("Warning: Unknown block versions being mined! It's possible unknown rules are in effect");
// notify GetWarnings(), called by Qt and the JSON-RPC code to warn the user:
LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu date='%s' progress=%f cache=%.1fMiB(%utxo)", __func__,
chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), chainActive.Tip()->nVersion,
log(chainActive.Tip()->nChainWork.getdouble())/log(2.0), (unsigned long)chainActive.Tip()->nChainTx,
DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
GuessVerificationProgress(chainParams.TxData(), chainActive.Tip()), pcoinsTip->DynamicMemoryUsage() * (1.0 / (1<<20)), pcoinsTip->GetCacheSize());
if (!warningMessages.empty())
LogPrintf(" warning='%s'", boost::algorithm::join(warningMessages, ", "));
/** Disconnect chainActive's tip.
* After calling, the mempool will be in an inconsistent state, with
* transactions from disconnected blocks being added to disconnectpool. You
* should make the mempool consistent again by calling UpdateMempoolForReorg.
* with cs_main held.
* If disconnectpool is NULL, then no disconnected transactions are added to
* disconnectpool (note that the caller is responsible for mempool consistency
* in any case).
bool static DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions *disconnectpool)
CBlockIndex *pindexDelete = chainActive.Tip();
// Read block from disk.
std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
CBlock& block = *pblock;
if (!ReadBlockFromDisk(block, pindexDelete, chainparams.GetConsensus()))
return AbortNode(state, "Failed to read block");
// Apply the block atomically to the chain state.
int64_t nStart = GetTimeMicros();
CCoinsViewCache view(pcoinsTip);
assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
if (DisconnectBlock(block, pindexDelete, view) != DISCONNECT_OK)
return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
bool flushed = view.Flush();
LogPrint(BCLog::BENCH, "- Disconnect block: %.2fms\n", (GetTimeMicros() - nStart) * 0.001);
// Write the chain state to disk, if necessary.
if (!FlushStateToDisk(chainparams, state, FLUSH_STATE_IF_NEEDED))
return false;
if (disconnectpool) {
// Save transactions to re-add to mempool at end of reorg
for (auto it = block.vtx.rbegin(); it != block.vtx.rend(); ++it) {
while (disconnectpool->DynamicMemoryUsage() > MAX_DISCONNECTED_TX_POOL_SIZE * 1000) {
// Drop the earliest entry, and remove its children from the mempool.
auto it = disconnectpool->queuedTx.get<insertion_order>().begin();
mempool.removeRecursive(**it, MemPoolRemovalReason::REORG);
// Update chainActive and related variables.
UpdateTip(pindexDelete->pprev, chainparams);
// Let wallets know transactions went from 1-confirmed to
// 0-confirmed or conflicted:
return true;
static int64_t nTimeReadFromDisk = 0;
static int64_t nTimeConnectTotal = 0;
static int64_t nTimeFlush = 0;
static int64_t nTimeChainState = 0;
static int64_t nTimePostConnect = 0;
struct PerBlockConnectTrace {
CBlockIndex* pindex = NULL;
std::shared_ptr<const CBlock> pblock;
std::shared_ptr<std::vector<CTransactionRef>> conflictedTxs;
PerBlockConnectTrace() : conflictedTxs(std::make_shared<std::vector<CTransactionRef>>()) {}
* Used to track blocks whose transactions were applied to the UTXO state as a
* part of a single ActivateBestChainStep call.
* This class also tracks transactions that are removed from the mempool as
* conflicts (per block) and can be used to pass all those transactions
* through SyncTransaction.
* This class assumes (and asserts) that the conflicted transactions for a given
* block are added via mempool callbacks prior to the BlockConnected() associated
* with those transactions. If any transactions are marked conflicted, it is
* assumed that an associated block will always be added.
* This class is single-use, once you call GetBlocksConnected() you have to throw
* it away and make a new one.
class ConnectTrace {
std::vector<PerBlockConnectTrace> blocksConnected;
CTxMemPool &pool;
ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {
pool.NotifyEntryRemoved.connect(boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
~ConnectTrace() {
pool.NotifyEntryRemoved.disconnect(boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
void BlockConnected(CBlockIndex* pindex, std::shared_ptr<const CBlock> pblock) {
blocksConnected.back().pindex = pindex;
blocksConnected.back().pblock = std::move(pblock);
std::vector<PerBlockConnectTrace>& GetBlocksConnected() {
// We always keep one extra block at the end of our list because
// blocks are added after all the conflicted transactions have
// been filled in. Thus, the last entry should always be an empty
// one waiting for the transactions from the next block. We pop
// the last entry here to make sure the list we return is sane.
return blocksConnected;
void NotifyEntryRemoved(CTransactionRef txRemoved, MemPoolRemovalReason reason) {
if (reason == MemPoolRemovalReason::CONFLICT) {
* Connect a new block to chainActive. pblock is either NULL or a pointer to a CBlock
* corresponding to pindexNew, to bypass loading it again from disk.
* The block is added to connectTrace if connection succeeds.
bool static ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool)
assert(pindexNew->pprev == chainActive.Tip());
// Read block from disk.
int64_t nTime1 = GetTimeMicros();
std::shared_ptr<const CBlock> pthisBlock;
if (!pblock) {
std::shared_ptr<CBlock> pblockNew = std::make_shared<CBlock>();
if (!ReadBlockFromDisk(*pblockNew, pindexNew, chainparams.GetConsensus()))
return AbortNode(state, "Failed to read block");
pthisBlock = pblockNew;
} else {
pthisBlock = pblock;
const CBlock& blockConnecting = *pthisBlock;
// Apply the block atomically to the chain state.
int64_t nTime2 = GetTimeMicros(); nTimeReadFromDisk += nTime2 - nTime1;
int64_t nTime3;
LogPrint(BCLog::BENCH, " - Load block from disk: %.2fms [%.2fs]\n", (nTime2 - nTime1) * 0.001, nTimeReadFromDisk * 0.000001);
CCoinsViewCache view(pcoinsTip);
bool rv = ConnectBlock(blockConnecting, state, pindexNew, view, chainparams);
GetMainSignals().BlockChecked(blockConnecting, state);
if (!rv) {
if (state.IsInvalid())
InvalidBlockFound(pindexNew, state);
return error("ConnectTip(): ConnectBlock %s failed", pindexNew->GetBlockHash().ToString());
nTime3 = GetTimeMicros(); nTimeConnectTotal += nTime3 - nTime2;
LogPrint(BCLog::BENCH, " - Connect total: %.2fms [%.2fs]\n", (nTime3 - nTime2) * 0.001, nTimeConnectTotal * 0.000001);
bool flushed = view.Flush();
int64_t nTime4 = GetTimeMicros(); nTimeFlush += nTime4 - nTime3;
LogPrint(BCLog::BENCH, " - Flush: %.2fms [%.2fs]\n", (nTime4 - nTime3) * 0.001, nTimeFlush * 0.000001);
// Write the chain state to disk, if necessary.
if (!FlushStateToDisk(chainparams, state, FLUSH_STATE_IF_NEEDED))
return false;
int64_t nTime5 = GetTimeMicros(); nTimeChainState += nTime5 - nTime4;
LogPrint(BCLog::BENCH, " - Writing chainstate: %.2fms [%.2fs]\n", (nTime5 - nTime4) * 0.001, nTimeChainState * 0.000001);
// Remove conflicting transactions from the mempool.;
mempool.removeForBlock(blockConnecting.vtx, pindexNew->nHeight);
// Update chainActive & related variables.
UpdateTip(pindexNew, chainparams);
int64_t nTime6 = GetTimeMicros(); nTimePostConnect += nTime6 - nTime5; nTimeTotal += nTime6 - nTime1;
LogPrint(BCLog::BENCH, " - Connect postprocess: %.2fms [%.2fs]\n", (nTime6 - nTime5) * 0.001, nTimePostConnect * 0.000001);
LogPrint(BCLog::BENCH, "- Connect block: %.2fms [%.2fs]\n", (nTime6 - nTime1) * 0.001, nTimeTotal * 0.000001);
connectTrace.BlockConnected(pindexNew, std::move(pthisBlock));
return true;
* Return the tip of the chain with the most work in it, that isn't
* known to be invalid (it's however far from certain to be valid).
static CBlockIndex* FindMostWorkChain() {
do {
CBlockIndex *pindexNew = NULL;
// Find the best candidate header.
std::set<CBlockIndex*, CBlockIndexWorkComparator>::reverse_iterator it = setBlockIndexCandidates.rbegin();
if (it == setBlockIndexCandidates.rend())
return NULL;
pindexNew = *it;
// Check whether all blocks on the path between the currently active chain and the candidate are valid.
// Just going until the active chain is an optimization, as we know all blocks in it are valid already.
CBlockIndex *pindexTest = pindexNew;
bool fInvalidAncestor = false;
while (pindexTest && !chainActive.Contains(pindexTest)) {
assert(pindexTest->nChainTx || pindexTest->nHeight == 0);
// Pruned nodes may have entries in setBlockIndexCandidates for
// which block files have been deleted. Remove those as candidates
// for the most work chain if we come across them; we can't switch
// to a chain unless we have all the non-active-chain parent blocks.
bool fFailedChain = pindexTest->nStatus & BLOCK_FAILED_MASK;
bool fMissingData = !(pindexTest->nStatus & BLOCK_HAVE_DATA);
if (fFailedChain || fMissingData) {
// Candidate chain is not usable (either invalid or missing data)
if (fFailedChain && (pindexBestInvalid == NULL || pindexNew->nChainWork > pindexBestInvalid->nChainWork))
pindexBestInvalid = pindexNew;
CBlockIndex *pindexFailed = pindexNew;
// Remove the entire chain from the set.
while (pindexTest != pindexFailed) {
if (fFailedChain) {
pindexFailed->nStatus |= BLOCK_FAILED_CHILD;
} else if (fMissingData) {
// If we're missing data, then add back to mapBlocksUnlinked,
// so that if the block arrives in the future we can try adding
// to setBlockIndexCandidates again.
mapBlocksUnlinked.insert(std::make_pair(pindexFailed->pprev, pindexFailed));
pindexFailed = pindexFailed->pprev;
fInvalidAncestor = true;
pindexTest = pindexTest->pprev;
if (!fInvalidAncestor)
return pindexNew;
} while(true);
/** Delete all entries in setBlockIndexCandidates that are worse than the current tip. */
static void PruneBlockIndexCandidates() {
// Note that we can't delete the current block itself, as we may need to return to it later in case a
// reorganization to a better block fails.
std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
while (it != setBlockIndexCandidates.end() && setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
// Either the current tip or a successor of it we're working towards is left in setBlockIndexCandidates.
* Try to make some progress towards making pindexMostWork the active block.
* pblock is either NULL or a pointer to a CBlock corresponding to pindexMostWork.
static bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace)
const CBlockIndex *pindexOldTip = chainActive.Tip();
const CBlockIndex *pindexFork = chainActive.FindFork(pindexMostWork);
// Disconnect active blocks which are no longer in the best chain.
bool fBlocksDisconnected = false;
DisconnectedBlockTransactions disconnectpool;
while (chainActive.Tip() && chainActive.Tip() != pindexFork) {
if (!DisconnectTip(state, chainparams, &disconnectpool)) {
// This is likely a fatal error, but keep the mempool consistent,
// just in case. Only remove from the mempool in this case.
UpdateMempoolForReorg(disconnectpool, false);
return false;
fBlocksDisconnected = true;
// Build list of new blocks to connect.
std::vector<CBlockIndex*> vpindexToConnect;
bool fContinue = true;
int nHeight = pindexFork ? pindexFork->nHeight : -1;
while (fContinue && nHeight != pindexMostWork->nHeight) {
// Don't iterate the entire list of potential improvements toward the best tip, as we likely only need
// a few blocks along the way.
int nTargetHeight = std::min(nHeight + 32, pindexMostWork->nHeight);
vpindexToConnect.reserve(nTargetHeight - nHeight);
CBlockIndex *pindexIter = pindexMostWork->GetAncestor(nTargetHeight);
while (pindexIter && pindexIter->nHeight != nHeight) {
pindexIter = pindexIter->pprev;
nHeight = nTargetHeight;
// Connect new blocks.
for (CBlockIndex *pindexConnect : reverse_iterate(vpindexToConnect)) {
if (!ConnectTip(state, chainparams, pindexConnect, pindexConnect == pindexMostWork ? pblock : std::shared_ptr<const CBlock>(), connectTrace, disconnectpool)) {
if (state.IsInvalid()) {
// The block violates a consensus rule.
if (!state.CorruptionPossible())
state = CValidationState();
fInvalidFound = true;
fContinue = false;
} else {
// A system error occurred (disk space, database error, ...).
// Make the mempool consistent with the current tip, just in case
// any observers try to use it before shutdown.
UpdateMempoolForReorg(disconnectpool, false);
return false;
} else {
if (!pindexOldTip || chainActive.Tip()->nChainWork > pindexOldTip->nChainWork) {
// We're in a better position than we were. Return temporarily to release the lock.
fContinue = false;
if (fBlocksDisconnected) {
// If any blocks were disconnected, disconnectpool may be non empty. Add
// any disconnected transactions back to the mempool.
UpdateMempoolForReorg(disconnectpool, true);
// Callbacks/notifications for a new best chain.
if (fInvalidFound)
return true;
static void NotifyHeaderTip() {
bool fNotify = false;
bool fInitialBlockDownload = false;
static CBlockIndex* pindexHeaderOld = NULL;
CBlockIndex* pindexHeader = NULL;
pindexHeader = pindexBestHeader;
if (pindexHeader != pindexHeaderOld) {
fNotify = true;
fInitialBlockDownload = IsInitialBlockDownload();
pindexHeaderOld = pindexHeader;
// Send block tip changed notifications without cs_main
if (fNotify) {
uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
* Make the best chain active, in multiple steps. The result is either failure
* or an activated best chain. pblock is either NULL or a pointer to a block
* that is already loaded (to avoid loading it again from disk).
bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) {
// Note that while we're often called here from ProcessNewBlock, this is
// far from a guarantee. Things in the P2P/RPC will often end up calling
// us in the middle of ProcessNewBlock - do not assume pblock is set
// sanely for performance or correctness!
CBlockIndex *pindexMostWork = NULL;
CBlockIndex *pindexNewTip = NULL;
int nStopAtHeight = GetArg("-stopatheight", DEFAULT_STOPATHEIGHT);
do {
if (ShutdownRequested())
const CBlockIndex *pindexFork;
bool fInitialDownload;
ConnectTrace connectTrace(mempool); // Destructed before cs_main is unlocked
CBlockIndex *pindexOldTip = chainActive.Tip();
if (pindexMostWork == NULL) {
pindexMostWork = FindMostWorkChain();
// Whether we have anything to do at all.
if (pindexMostWork == NULL || pindexMostWork == chainActive.Tip())
return true;
bool fInvalidFound = false;
std::shared_ptr<const CBlock> nullBlockPtr;
if (!ActivateBestChainStep(state, chainparams, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : nullBlockPtr, fInvalidFound, connectTrace))
return false;
if (fInvalidFound) {
// Wipe cache, we may need another branch now.
pindexMostWork = NULL;
pindexNewTip = chainActive.Tip();
pindexFork = chainActive.FindFork(pindexOldTip);
fInitialDownload = IsInitialBlockDownload();
for (const PerBlockConnectTrace& trace : connectTrace.GetBlocksConnected()) {
assert(trace.pblock && trace.pindex);
GetMainSignals().BlockConnected(trace.pblock, trace.pindex, *trace.conflictedTxs);
// When we reach this point, we switched to a new tip (stored in pindexNewTip).
// Notifications/callbacks that can run without cs_main
// Notify external listeners about the new tip.
GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload);
// Always notify the UI if a new block tip was connected
if (pindexFork != pindexNewTip) {
uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip);
if (nStopAtHeight && pindexNewTip && pindexNewTip->nHeight >= nStopAtHeight) StartShutdown();
} while (pindexNewTip != pindexMostWork);
// Write changes periodically to disk, after relay.
if (!FlushStateToDisk(chainparams, state, FLUSH_STATE_PERIODIC)) {
return false;
return true;
bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex *pindex)
if (pindex->nChainWork < chainActive.Tip()->nChainWork) {
// Nothing to do, this block is not at the tip.
return true;