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// Copyright (c) 2021 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 <txorphanage.h>
#include <consensus/validation.h>
#include <logging.h>
#include <policy/policy.h>
#include <cassert>
/** Expiration time for orphan transactions in seconds */
static constexpr int64_t ORPHAN_TX_EXPIRE_TIME = 20 * 60;
/** Minimum time between orphan transactions expire time checks in seconds */
static constexpr int64_t ORPHAN_TX_EXPIRE_INTERVAL = 5 * 60;
RecursiveMutex g_cs_orphans;
bool TxOrphanage::AddTx(const CTransactionRef& tx, NodeId peer)
{
AssertLockHeld(g_cs_orphans);
const uint256& hash = tx->GetHash();
if (m_orphans.count(hash))
return false;
// Ignore big transactions, to avoid a
// send-big-orphans memory exhaustion attack. If a peer has a legitimate
// large transaction with a missing parent then we assume
// it will rebroadcast it later, after the parent transaction(s)
// have been mined or received.
// 100 orphans, each of which is at most 100,000 bytes big is
// at most 10 megabytes of orphans and somewhat more byprev index (in the worst case):
unsigned int sz = GetTransactionWeight(*tx);
if (sz > MAX_STANDARD_TX_WEIGHT)
{
LogPrint(BCLog::MEMPOOL, "ignoring large orphan tx (size: %u, hash: %s)\n", sz, hash.ToString());
return false;
}
auto ret = m_orphans.emplace(hash, OrphanTx{tx, peer, GetTime() + ORPHAN_TX_EXPIRE_TIME, m_orphan_list.size()});
assert(ret.second);
m_orphan_list.push_back(ret.first);
// Allow for lookups in the orphan pool by wtxid, as well as txid
m_wtxid_to_orphan_it.emplace(tx->GetWitnessHash(), ret.first);
for (const CTxIn& txin : tx->vin) {
m_outpoint_to_orphan_it[txin.prevout].insert(ret.first);
}
LogPrint(BCLog::MEMPOOL, "stored orphan tx %s (mapsz %u outsz %u)\n", hash.ToString(),
m_orphans.size(), m_outpoint_to_orphan_it.size());
return true;
}
int TxOrphanage::EraseTx(const uint256& txid)
{
AssertLockHeld(g_cs_orphans);
std::map<uint256, OrphanTx>::iterator it = m_orphans.find(txid);
if (it == m_orphans.end())
return 0;
for (const CTxIn& txin : it->second.tx->vin)
{
auto itPrev = m_outpoint_to_orphan_it.find(txin.prevout);
if (itPrev == m_outpoint_to_orphan_it.end())
continue;
itPrev->second.erase(it);
if (itPrev->second.empty())
m_outpoint_to_orphan_it.erase(itPrev);
}
size_t old_pos = it->second.list_pos;
assert(m_orphan_list[old_pos] == it);
if (old_pos + 1 != m_orphan_list.size()) {
// Unless we're deleting the last entry in m_orphan_list, move the last
// entry to the position we're deleting.
auto it_last = m_orphan_list.back();
m_orphan_list[old_pos] = it_last;
it_last->second.list_pos = old_pos;
}
m_orphan_list.pop_back();
m_wtxid_to_orphan_it.erase(it->second.tx->GetWitnessHash());
m_orphans.erase(it);
return 1;
}
void TxOrphanage::EraseForPeer(NodeId peer)
{
AssertLockHeld(g_cs_orphans);
int nErased = 0;
std::map<uint256, OrphanTx>::iterator iter = m_orphans.begin();
while (iter != m_orphans.end())
{
std::map<uint256, OrphanTx>::iterator maybeErase = iter++; // increment to avoid iterator becoming invalid
if (maybeErase->second.fromPeer == peer)
{
nErased += EraseTx(maybeErase->second.tx->GetHash());
}
}
if (nErased > 0) LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx from peer=%d\n", nErased, peer);
}
unsigned int TxOrphanage::LimitOrphans(unsigned int max_orphans)
{
AssertLockHeld(g_cs_orphans);
unsigned int nEvicted = 0;
static int64_t nNextSweep;
int64_t nNow = GetTime();
if (nNextSweep <= nNow) {
// Sweep out expired orphan pool entries:
int nErased = 0;
int64_t nMinExpTime = nNow + ORPHAN_TX_EXPIRE_TIME - ORPHAN_TX_EXPIRE_INTERVAL;
std::map<uint256, OrphanTx>::iterator iter = m_orphans.begin();
while (iter != m_orphans.end())
{
std::map<uint256, OrphanTx>::iterator maybeErase = iter++;
if (maybeErase->second.nTimeExpire <= nNow) {
nErased += EraseTx(maybeErase->second.tx->GetHash());
} else {
nMinExpTime = std::min(maybeErase->second.nTimeExpire, nMinExpTime);
}
}
// Sweep again 5 minutes after the next entry that expires in order to batch the linear scan.
nNextSweep = nMinExpTime + ORPHAN_TX_EXPIRE_INTERVAL;
if (nErased > 0) LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx due to expiration\n", nErased);
}
FastRandomContext rng;
while (m_orphans.size() > max_orphans)
{
// Evict a random orphan:
size_t randompos = rng.randrange(m_orphan_list.size());
EraseTx(m_orphan_list[randompos]->first);
++nEvicted;
}
return nEvicted;
}
void TxOrphanage::AddChildrenToWorkSet(const CTransaction& tx, std::set<uint256>& orphan_work_set) const
{
AssertLockHeld(g_cs_orphans);
for (unsigned int i = 0; i < tx.vout.size(); i++) {
const auto it_by_prev = m_outpoint_to_orphan_it.find(COutPoint(tx.GetHash(), i));
if (it_by_prev != m_outpoint_to_orphan_it.end()) {
for (const auto& elem : it_by_prev->second) {
orphan_work_set.insert(elem->first);
}
}
}
}
bool TxOrphanage::HaveTx(const GenTxid& gtxid) const
{
LOCK(g_cs_orphans);
if (gtxid.IsWtxid()) {
return m_wtxid_to_orphan_it.count(gtxid.GetHash());
} else {
return m_orphans.count(gtxid.GetHash());
}
}
std::pair<CTransactionRef, NodeId> TxOrphanage::GetTx(const uint256& txid) const
{
AssertLockHeld(g_cs_orphans);
const auto it = m_orphans.find(txid);
if (it == m_orphans.end()) return {nullptr, -1};
return {it->second.tx, it->second.fromPeer};
}
void TxOrphanage::EraseForBlock(const CBlock& block)
{
LOCK(g_cs_orphans);
std::vector<uint256> vOrphanErase;
for (const CTransactionRef& ptx : block.vtx) {
const CTransaction& tx = *ptx;
// Which orphan pool entries must we evict?
for (const auto& txin : tx.vin) {
auto itByPrev = m_outpoint_to_orphan_it.find(txin.prevout);
if (itByPrev == m_outpoint_to_orphan_it.end()) continue;
for (auto mi = itByPrev->second.begin(); mi != itByPrev->second.end(); ++mi) {
const CTransaction& orphanTx = *(*mi)->second.tx;
const uint256& orphanHash = orphanTx.GetHash();
vOrphanErase.push_back(orphanHash);
}
}
}
// Erase orphan transactions included or precluded by this block
if (vOrphanErase.size()) {
int nErased = 0;
for (const uint256& orphanHash : vOrphanErase) {
nErased += EraseTx(orphanHash);
}
LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx included or conflicted by block\n", nErased);
}
}
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