1  // Copyright (c) 2021-2022 The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #include <txorphanage.h>
  6  
  7  #include <consensus/validation.h>
  8  #include <logging.h>
  9  #include <policy/policy.h>
 10  #include <primitives/transaction.h>
 11  
 12  #include <cassert>
 13  
 14  /** Expiration time for orphan transactions in seconds */
 15  static constexpr int64_t ORPHAN_TX_EXPIRE_TIME = 20 * 60;
 16  /** Minimum time between orphan transactions expire time checks in seconds */
 17  static constexpr int64_t ORPHAN_TX_EXPIRE_INTERVAL = 5 * 60;
 18  
 19  
 20  bool TxOrphanage::AddTx(const CTransactionRef& tx, NodeId peer)
 21  {
 22      LOCK(m_mutex);
 23  
 24      const Txid& hash = tx->GetHash();
 25      const Wtxid& wtxid = tx->GetWitnessHash();
 26      if (m_orphans.count(hash))
 27          return false;
 28  
 29      // Ignore big transactions, to avoid a
 30      // send-big-orphans memory exhaustion attack. If a peer has a legitimate
 31      // large transaction with a missing parent then we assume
 32      // it will rebroadcast it later, after the parent transaction(s)
 33      // have been mined or received.
 34      // 100 orphans, each of which is at most 100,000 bytes big is
 35      // at most 10 megabytes of orphans and somewhat more byprev index (in the worst case):
 36      unsigned int sz = GetTransactionWeight(*tx);
 37      if (sz > MAX_STANDARD_TX_WEIGHT)
 38      {
 39          LogPrint(BCLog::TXPACKAGES, "ignoring large orphan tx (size: %u, txid: %s, wtxid: %s)\n", sz, hash.ToString(), wtxid.ToString());
 40          return false;
 41      }
 42  
 43      auto ret = m_orphans.emplace(hash, OrphanTx{tx, peer, GetTime() + ORPHAN_TX_EXPIRE_TIME, m_orphan_list.size()});
 44      assert(ret.second);
 45      m_orphan_list.push_back(ret.first);
 46      // Allow for lookups in the orphan pool by wtxid, as well as txid
 47      m_wtxid_to_orphan_it.emplace(tx->GetWitnessHash(), ret.first);
 48      for (const CTxIn& txin : tx->vin) {
 49          m_outpoint_to_orphan_it[txin.prevout].insert(ret.first);
 50      }
 51  
 52      LogPrint(BCLog::TXPACKAGES, "stored orphan tx %s (wtxid=%s) (mapsz %u outsz %u)\n", hash.ToString(), wtxid.ToString(),
 53               m_orphans.size(), m_outpoint_to_orphan_it.size());
 54      return true;
 55  }
 56  
 57  int TxOrphanage::EraseTx(const Txid& txid)
 58  {
 59      LOCK(m_mutex);
 60      return EraseTxNoLock(txid);
 61  }
 62  
 63  int TxOrphanage::EraseTxNoLock(const Txid& txid)
 64  {
 65      AssertLockHeld(m_mutex);
 66      std::map<Txid, OrphanTx>::iterator it = m_orphans.find(txid);
 67      if (it == m_orphans.end())
 68          return 0;
 69      for (const CTxIn& txin : it->second.tx->vin)
 70      {
 71          auto itPrev = m_outpoint_to_orphan_it.find(txin.prevout);
 72          if (itPrev == m_outpoint_to_orphan_it.end())
 73              continue;
 74          itPrev->second.erase(it);
 75          if (itPrev->second.empty())
 76              m_outpoint_to_orphan_it.erase(itPrev);
 77      }
 78  
 79      size_t old_pos = it->second.list_pos;
 80      assert(m_orphan_list[old_pos] == it);
 81      if (old_pos + 1 != m_orphan_list.size()) {
 82          // Unless we're deleting the last entry in m_orphan_list, move the last
 83          // entry to the position we're deleting.
 84          auto it_last = m_orphan_list.back();
 85          m_orphan_list[old_pos] = it_last;
 86          it_last->second.list_pos = old_pos;
 87      }
 88      const auto& wtxid = it->second.tx->GetWitnessHash();
 89      LogPrint(BCLog::TXPACKAGES, "   removed orphan tx %s (wtxid=%s)\n", txid.ToString(), wtxid.ToString());
 90      m_orphan_list.pop_back();
 91      m_wtxid_to_orphan_it.erase(it->second.tx->GetWitnessHash());
 92  
 93      m_orphans.erase(it);
 94      return 1;
 95  }
 96  
 97  void TxOrphanage::EraseForPeer(NodeId peer)
 98  {
 99      LOCK(m_mutex);
100  
101      m_peer_work_set.erase(peer);
102  
103      int nErased = 0;
104      std::map<Txid, OrphanTx>::iterator iter = m_orphans.begin();
105      while (iter != m_orphans.end())
106      {
107          std::map<Txid, OrphanTx>::iterator maybeErase = iter++; // increment to avoid iterator becoming invalid
108          if (maybeErase->second.fromPeer == peer)
109          {
110              nErased += EraseTxNoLock(maybeErase->second.tx->GetHash());
111          }
112      }
113      if (nErased > 0) LogPrint(BCLog::TXPACKAGES, "Erased %d orphan tx from peer=%d\n", nErased, peer);
114  }
115  
116  void TxOrphanage::LimitOrphans(unsigned int max_orphans, FastRandomContext& rng)
117  {
118      LOCK(m_mutex);
119  
120      unsigned int nEvicted = 0;
121      static int64_t nNextSweep;
122      int64_t nNow = GetTime();
123      if (nNextSweep <= nNow) {
124          // Sweep out expired orphan pool entries:
125          int nErased = 0;
126          int64_t nMinExpTime = nNow + ORPHAN_TX_EXPIRE_TIME - ORPHAN_TX_EXPIRE_INTERVAL;
127          std::map<Txid, OrphanTx>::iterator iter = m_orphans.begin();
128          while (iter != m_orphans.end())
129          {
130              std::map<Txid, OrphanTx>::iterator maybeErase = iter++;
131              if (maybeErase->second.nTimeExpire <= nNow) {
132                  nErased += EraseTxNoLock(maybeErase->second.tx->GetHash());
133              } else {
134                  nMinExpTime = std::min(maybeErase->second.nTimeExpire, nMinExpTime);
135              }
136          }
137          // Sweep again 5 minutes after the next entry that expires in order to batch the linear scan.
138          nNextSweep = nMinExpTime + ORPHAN_TX_EXPIRE_INTERVAL;
139          if (nErased > 0) LogPrint(BCLog::TXPACKAGES, "Erased %d orphan tx due to expiration\n", nErased);
140      }
141      while (m_orphans.size() > max_orphans)
142      {
143          // Evict a random orphan:
144          size_t randompos = rng.randrange(m_orphan_list.size());
145          EraseTxNoLock(m_orphan_list[randompos]->first);
146          ++nEvicted;
147      }
148      if (nEvicted > 0) LogPrint(BCLog::TXPACKAGES, "orphanage overflow, removed %u tx\n", nEvicted);
149  }
150  
151  void TxOrphanage::AddChildrenToWorkSet(const CTransaction& tx)
152  {
153      LOCK(m_mutex);
154  
155  
156      for (unsigned int i = 0; i < tx.vout.size(); i++) {
157          const auto it_by_prev = m_outpoint_to_orphan_it.find(COutPoint(tx.GetHash(), i));
158          if (it_by_prev != m_outpoint_to_orphan_it.end()) {
159              for (const auto& elem : it_by_prev->second) {
160                  // Get this source peer's work set, emplacing an empty set if it didn't exist
161                  // (note: if this peer wasn't still connected, we would have removed the orphan tx already)
162                  std::set<Txid>& orphan_work_set = m_peer_work_set.try_emplace(elem->second.fromPeer).first->second;
163                  // Add this tx to the work set
164                  orphan_work_set.insert(elem->first);
165                  LogPrint(BCLog::TXPACKAGES, "added %s (wtxid=%s) to peer %d workset\n",
166                           tx.GetHash().ToString(), tx.GetWitnessHash().ToString(), elem->second.fromPeer);
167              }
168          }
169      }
170  }
171  
172  bool TxOrphanage::HaveTx(const GenTxid& gtxid) const
173  {
174      LOCK(m_mutex);
175      if (gtxid.IsWtxid()) {
176          return m_wtxid_to_orphan_it.count(Wtxid::FromUint256(gtxid.GetHash()));
177      } else {
178          return m_orphans.count(Txid::FromUint256(gtxid.GetHash()));
179      }
180  }
181  
182  CTransactionRef TxOrphanage::GetTxToReconsider(NodeId peer)
183  {
184      LOCK(m_mutex);
185  
186      auto work_set_it = m_peer_work_set.find(peer);
187      if (work_set_it != m_peer_work_set.end()) {
188          auto& work_set = work_set_it->second;
189          while (!work_set.empty()) {
190              Txid txid = *work_set.begin();
191              work_set.erase(work_set.begin());
192  
193              const auto orphan_it = m_orphans.find(txid);
194              if (orphan_it != m_orphans.end()) {
195                  return orphan_it->second.tx;
196              }
197          }
198      }
199      return nullptr;
200  }
201  
202  bool TxOrphanage::HaveTxToReconsider(NodeId peer)
203  {
204      LOCK(m_mutex);
205  
206      auto work_set_it = m_peer_work_set.find(peer);
207      if (work_set_it != m_peer_work_set.end()) {
208          auto& work_set = work_set_it->second;
209          return !work_set.empty();
210      }
211      return false;
212  }
213  
214  void TxOrphanage::EraseForBlock(const CBlock& block)
215  {
216      LOCK(m_mutex);
217  
218      std::vector<Txid> vOrphanErase;
219  
220      for (const CTransactionRef& ptx : block.vtx) {
221          const CTransaction& tx = *ptx;
222  
223          // Which orphan pool entries must we evict?
224          for (const auto& txin : tx.vin) {
225              auto itByPrev = m_outpoint_to_orphan_it.find(txin.prevout);
226              if (itByPrev == m_outpoint_to_orphan_it.end()) continue;
227              for (auto mi = itByPrev->second.begin(); mi != itByPrev->second.end(); ++mi) {
228                  const CTransaction& orphanTx = *(*mi)->second.tx;
229                  const auto& orphanHash = orphanTx.GetHash();
230                  vOrphanErase.push_back(orphanHash);
231              }
232          }
233      }
234  
235      // Erase orphan transactions included or precluded by this block
236      if (vOrphanErase.size()) {
237          int nErased = 0;
238          for (const auto& orphanHash : vOrphanErase) {
239              nErased += EraseTxNoLock(orphanHash);
240          }
241          LogPrint(BCLog::TXPACKAGES, "Erased %d orphan tx included or conflicted by block\n", nErased);
242      }
243  }