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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 "chainparams.h"
#include "checkpoints.h"
#include "checkqueue.h"
#include "consensus/consensus.h"
#include "consensus/merkle.h"
#include "consensus/validation.h"
#include "hash.h"
#include "init.h"
#include "policy/fees.h"
#include "policy/policy.h"
#include "pow.h"
#include "primitives/block.h"
#include "primitives/transaction.h"
#include "random.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 <atomic>
#include <sstream>
#include <boost/algorithm/string/replace.hpp>
#include <boost/algorithm/string/join.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
#include <boost/math/distributions/poisson.hpp>
#include <boost/thread.hpp>
using namespace std;
#if defined(NDEBUG)
# error "Bitcoin cannot be compiled without assertions."
#endif
/**
* 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 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;
CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
CTxMemPool mempool(::minRelayTxFee);
static void CheckBlockIndex(const Consensus::Params& consensusParams);
/** Constant stuff for coinbase transactions we create: */
CScript COINBASE_FLAGS;
const string strMessageMagic = "Bitcoin Signed Message:\n";
// Internal stuff
namespace {
struct CBlockIndexWorkComparator
{
bool operator()(CBlockIndex *pa, 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.
*/
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.
*/
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. */
set<CBlockIndex*> setDirtyBlockIndex;
/** Dirty block file entries. */
set<int> setDirtyFileInfo;
} // anon namespace
CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
{
// Find the first block the caller has in the main chain
BOOST_FOREACH(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();
}
CCoinsViewCache *pcoinsTip = NULL;
CBlockTreeDB *pblocktree = NULL;
enum FlushStateMode {
FLUSH_STATE_NONE,
FLUSH_STATE_IF_NEEDED,
FLUSH_STATE_PERIODIC,
FLUSH_STATE_ALWAYS
};
// See definition for documentation
bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode);
bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
{
if (tx.nLockTime == 0)
return true;
if ((int64_t)tx.nLockTime < ((int64_t)tx.nLockTime < LOCKTIME_THRESHOLD ? (int64_t)nBlockHeight : nBlockTime))
return true;
for (const auto& txin : tx.vin) {
if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL))
return false;
}
return true;
}
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 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);
}
/**
* Calculates the block height and previous block's median time past at
* which the transaction will be considered final in the context of BIP 68.
* Also removes from the vector of input heights any entries which did not
* correspond to sequence locked inputs as they do not affect the calculation.
*/
static std::pair<int, int64_t> CalculateSequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
{
assert(prevHeights->size() == tx.vin.size());
// Will be set to the equivalent height- and time-based nLockTime
// values that would be necessary to satisfy all relative lock-
// time constraints given our view of block chain history.
// The semantics of nLockTime are the last invalid height/time, so
// use -1 to have the effect of any height or time being valid.
int nMinHeight = -1;
int64_t nMinTime = -1;
// tx.nVersion is signed integer so requires cast to unsigned otherwise
// we would be doing a signed comparison and half the range of nVersion
// wouldn't support BIP 68.
bool fEnforceBIP68 = static_cast<uint32_t>(tx.nVersion) >= 2
&& flags & LOCKTIME_VERIFY_SEQUENCE;
// Do not enforce sequence numbers as a relative lock time
// unless we have been instructed to
if (!fEnforceBIP68) {
return std::make_pair(nMinHeight, nMinTime);
}
for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
const CTxIn& txin = tx.vin[txinIndex];
// Sequence numbers with the most significant bit set are not
// treated as relative lock-times, nor are they given any
// consensus-enforced meaning at this point.
if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) {
// The height of this input is not relevant for sequence locks
(*prevHeights)[txinIndex] = 0;
continue;
}
int nCoinHeight = (*prevHeights)[txinIndex];
if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) {
int64_t nCoinTime = block.GetAncestor(std::max(nCoinHeight-1, 0))->GetMedianTimePast();
// NOTE: Subtract 1 to maintain nLockTime semantics
// BIP 68 relative lock times have the semantics of calculating
// the first block or time at which the transaction would be
// valid. When calculating the effective block time or height
// for the entire transaction, we switch to using the
// semantics of nLockTime which is the last invalid block
// time or height. Thus we subtract 1 from the calculated
// time or height.
// Time-based relative lock-times are measured from the
// smallest allowed timestamp of the block containing the
// txout being spent, which is the median time past of the
// block prior.
nMinTime = std::max(nMinTime, nCoinTime + (int64_t)((txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) << CTxIn::SEQUENCE_LOCKTIME_GRANULARITY) - 1);
} else {
nMinHeight = std::max(nMinHeight, nCoinHeight + (int)(txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) - 1);
}
}
return std::make_pair(nMinHeight, nMinTime);
}
static bool EvaluateSequenceLocks(const CBlockIndex& block, std::pair<int, int64_t> lockPair)
{
assert(block.pprev);
int64_t nBlockTime = block.pprev->GetMedianTimePast();
if (lockPair.first >= block.nHeight || lockPair.second >= nBlockTime)
return false;
return true;
}
bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
{
return EvaluateSequenceLocks(block, CalculateSequenceLocks(tx, flags, prevHeights, block));
}
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();
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];
CCoins coins;
if (!viewMemPool.GetCoins(txin.prevout.hash, coins)) {
return error("%s: Missing input", __func__);
}
if (coins.nHeight == MEMPOOL_HEIGHT) {
// Assume all mempool transaction confirm in the next block
prevheights[txinIndex] = tip->nHeight + 1;
} else {
prevheights[txinIndex] = coins.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;
BOOST_FOREACH(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);
}
unsigned int GetLegacySigOpCount(const CTransaction& tx)
{
unsigned int nSigOps = 0;
for (const auto& txin : tx.vin)
{
nSigOps += txin.scriptSig.GetSigOpCount(false);
}
for (const auto& txout : tx.vout)
{
nSigOps += txout.scriptPubKey.GetSigOpCount(false);
}
return nSigOps;
}
unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& inputs)
{
if (tx.IsCoinBase())
return 0;
unsigned int nSigOps = 0;
for (unsigned int i = 0; i < tx.vin.size(); i++)
{
const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]);
if (prevout.scriptPubKey.IsPayToScriptHash())
nSigOps += prevout.scriptPubKey.GetSigOpCount(tx.vin[i].scriptSig);
}
return nSigOps;
}
int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags)
{
int64_t nSigOps = GetLegacySigOpCount(tx) * WITNESS_SCALE_FACTOR;
if (tx.IsCoinBase())
return nSigOps;
if (flags & SCRIPT_VERIFY_P2SH) {
nSigOps += GetP2SHSigOpCount(tx, inputs) * WITNESS_SCALE_FACTOR;
}
for (unsigned int i = 0; i < tx.vin.size(); i++)
{
const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]);
nSigOps += CountWitnessSigOps(tx.vin[i].scriptSig, prevout.scriptPubKey, i < tx.wit.vtxinwit.size() ? &tx.wit.vtxinwit[i].scriptWitness : NULL, flags);
}
return nSigOps;
}
bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fCheckDuplicateInputs)
{
// Basic checks that don't depend on any context
if (tx.vin.empty())
return state.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty");
if (tx.vout.empty())
return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
// Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_BASE_SIZE)
return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
// Check for negative or overflow output values
CAmount nValueOut = 0;
for (const auto& txout : tx.vout)
{
if (txout.nValue < 0)
return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative");
if (txout.nValue > MAX_MONEY)
return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge");
nValueOut += txout.nValue;
if (!MoneyRange(nValueOut))
return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
}
// Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
if (fCheckDuplicateInputs) {
set<COutPoint> vInOutPoints;
for (const auto& txin : tx.vin)
{
if (!vInOutPoints.insert(txin.prevout).second)
return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
}
}
if (tx.IsCoinBase())
{
if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
}
else
{
for (const auto& txin : tx.vin)
if (txin.prevout.IsNull())
return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null");
}
return true;
}
void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age) {
int expired = pool.Expire(GetTime() - age);
if (expired != 0)
LogPrint("mempool", "Expired %i transactions from the memory pool\n", expired);
std::vector<uint256> vNoSpendsRemaining;
pool.TrimToSize(limit, &vNoSpendsRemaining);
BOOST_FOREACH(const uint256& 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());
}
bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const CTransaction& tx, bool fLimitFree,
bool* pfMissingInputs, int64_t nAcceptTime, bool fOverrideMempoolLimit, const CAmount& nAbsurdFee,
std::vector<uint256>& vHashTxnToUncache)
{
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");
// Don't relay version 2 transactions until CSV is active, and we can be
// sure that such transactions will be mined (unless we're on
// -testnet/-regtest).
const CChainParams& chainparams = Params();
if (fRequireStandard && tx.nVersion >= 2 && VersionBitsTipState(chainparams.GetConsensus(), Consensus::DEPLOYMENT_CSV) != THRESHOLD_ACTIVE) {
return state.DoS(0, false, REJECT_NONSTANDARD, "premature-version2-tx");
}
// Reject transactions with witness before segregated witness activates (override with -prematurewitness)
bool witnessEnabled = IsWitnessEnabled(chainActive.Tip(), Params().GetConsensus());
if (!GetBoolArg("-prematurewitness",false) && !tx.wit.IsNull() && !witnessEnabled) {
return state.DoS(0, false, REJECT_NONSTANDARD, "no-witness-yet", true);
}
// Rather not work on nonstandard transactions (unless -testnet/-regtest)
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_ALREADY_KNOWN, "txn-already-in-mempool");
// Check for conflicts with in-memory transactions
set<uint256> setConflicts;
{
LOCK(pool.cs); // protect pool.mapNextTx
BOOST_FOREACH(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 >= maxint-1 on all inputs.
//
// maxint-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)
{
BOOST_FOREACH(const CTxIn &_txin, ptxConflicting->vin)
{
if (_txin.nSequence < std::numeric_limits<unsigned int>::max()-1)
{
fReplacementOptOut = false;
break;
}
}
}
if (fReplacementOptOut)
return state.Invalid(false, REJECT_CONFLICT, "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 we already have it?
bool fHadTxInCache = pcoinsTip->HaveCoinsInCache(hash);
if (view.HaveCoins(hash)) {
if (!fHadTxInCache)
vHashTxnToUncache.push_back(hash);
return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-known");
}
// do all inputs exist?
// Note that this does not check for the presence of actual outputs (see the next check for that),
// and only helps with filling in pfMissingInputs (to determine missing vs spent).
BOOST_FOREACH(const CTxIn txin, tx.vin) {
if (!pcoinsTip->HaveCoinsInCache(txin.prevout.hash))
vHashTxnToUncache.push_back(txin.prevout.hash);
if (!view.HaveCoins(txin.prevout.hash)) {
if (pfMissingInputs)
*pfMissingInputs = true;
return false; // fMissingInputs and !state.IsInvalid() is used to detect this condition, don't set state.Invalid()
}
}
// are the actual inputs available?
if (!view.HaveInputs(tx))
return state.Invalid(false, REJECT_DUPLICATE, "bad-txns-inputs-spent");
// 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.wit.IsNull() && 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;
double nPriorityDummy = 0;
pool.ApplyDeltas(hash, nPriorityDummy, nModifiedFees);
CAmount inChainInputValue;
double dPriority = view.GetPriority(tx, chainActive.Height(), inChainInputValue);
// Keep track of transactions that spend a coinbase, which we re-scan
// during reorgs to ensure COINBASE_MATURITY is still met.
bool fSpendsCoinbase = false;
BOOST_FOREACH(const CTxIn &txin, tx.vin) {
const CCoins *coins = view.AccessCoins(txin.prevout.hash);
if (coins->IsCoinBase()) {
fSpendsCoinbase = true;
break;
}
}
CTxMemPoolEntry entry(tx, nFees, nAcceptTime, dPriority, chainActive.Height(), pool.HasNoInputsOf(tx), inChainInputValue, 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(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));
} else if (GetBoolArg("-relaypriority", DEFAULT_RELAYPRIORITY) && nModifiedFees < ::minRelayTxFee.GetFee(nSize) && !AllowFree(entry.GetPriority(chainActive.Height() + 1))) {
// Require that free transactions have sufficient priority to be mined in the next block.
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "insufficient priority");
}
// Continuously rate-limit free (really, very-low-fee) transactions
// This mitigates 'penny-flooding' -- sending thousands of free transactions just to
// be annoying or make others' transactions take longer to confirm.
if (fLimitFree && nModifiedFees < ::minRelayTxFee.GetFee(nSize))
{
static CCriticalSection csFreeLimiter;
static double dFreeCount;
static int64_t nLastTime;
int64_t nNow = GetTime();
LOCK(csFreeLimiter);
// Use an exponentially decaying ~10-minute window:
dFreeCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
nLastTime = nNow;
// -limitfreerelay unit is thousand-bytes-per-minute
// At default rate it would take over a month to fill 1GB
if (dFreeCount + nSize >= GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) * 10 * 1000)
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "rate limited free transaction");
LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
dFreeCount += nSize;
}
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.
BOOST_FOREACH(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);
if (setConflicts.size())
{
CFeeRate newFeeRate(nModifiedFees, nSize);
set<uint256> setConflictsParents;
const int maxDescendantsToVisit = 100;
CTxMemPool::setEntries setIterConflicting;
BOOST_FOREACH(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()));
}
BOOST_FOREACH(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
BOOST_FOREACH(CTxMemPool::txiter it, setIterConflicting) {
pool.CalculateDescendants(it, allConflicting);
}
BOOST_FOREACH(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 < ::minRelayTxFee.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(::minRelayTxFee.GetFee(nSize))));
}
}
unsigned int scriptVerifyFlags = STANDARD_SCRIPT_VERIFY_FLAGS;
if (!Params().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, 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.
if (tx.wit.IsNull() && CheckInputs(tx, state, view, true, scriptVerifyFlags & ~(SCRIPT_VERIFY_WITNESS | SCRIPT_VERIFY_CLEANSTACK), true, txdata) &&
!CheckInputs(tx, state, view, true, scriptVerifyFlags & ~SCRIPT_VERIFY_CLEANSTACK, true, txdata)) {
// Only the witness is missing, so the transaction itself may be fine.
state.SetCorruptionPossible();
}
return false;
}
// Check again against just the consensus-critical mandatory script
// verification flags, 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, however allowing such transactions into the mempool
// can be exploited as a DoS attack.
if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true, txdata))
{
return error("%s: BUG! PLEASE REPORT THIS! ConnectInputs failed against MANDATORY but not STANDARD flags %s, %s",
__func__, hash.ToString(), FormatStateMessage(state));
}
// Remove conflicting transactions from the mempool
BOOST_FOREACH(const CTxMemPool::txiter it, allConflicting)
{
LogPrint("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);
}
pool.RemoveStaged(allConflicting, false);
// Store transaction in memory
pool.addUnchecked(hash, entry, setAncestors, !IsInitialBlockDownload());
// 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");
}
}
GetMainSignals().SyncTransaction(tx, NULL, CMainSignals::SYNC_TRANSACTION_NOT_IN_BLOCK);
return true;
}
bool AcceptToMemoryPoolWithTime(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
bool* pfMissingInputs, int64_t nAcceptTime, bool fOverrideMempoolLimit, const CAmount nAbsurdFee)
{
std::vector<uint256> vHashTxToUncache;
bool res = AcceptToMemoryPoolWorker(pool, state, tx, fLimitFree, pfMissingInputs, nAcceptTime, fOverrideMempoolLimit, nAbsurdFee, vHashTxToUncache);
if (!res) {
BOOST_FOREACH(const uint256& hashTx, vHashTxToUncache)
pcoinsTip->Uncache(hashTx);
}
// After we've (potentially) uncached entries, ensure our coins cache is still within its size limits
CValidationState stateDummy;
FlushStateToDisk(stateDummy, FLUSH_STATE_PERIODIC);
return res;
}
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
bool* pfMissingInputs, bool fOverrideMempoolLimit, const CAmount nAbsurdFee)
{
return AcceptToMemoryPoolWithTime(pool, state, tx, fLimitFree, pfMissingInputs, GetTime(), 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, CTransaction &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock, bool fAllowSlow)
{
CBlockIndex *pindexSlow = NULL;
LOCK(cs_main);
CTransactionRef ptx = mempool.get(hash);
if (ptx)
{
txOut = *ptx;
return true;
}
if (fTxIndex) {