[Mempool] Remove txes spending from a disconnected root

random-zebra · random-zebra · commit 4813286202f8 · 2020-11-11T14:38:27.000+01:00
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
@@ -536,6 +536,31 @@ void CTxMemPool::removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMem
     }
 }
 
+void CTxMemPool::removeWithAnchor(const uint256& invalidRoot)
+{
+
+    // If a block is disconnected from the tip, and the root changed,
+    // we must invalidate transactions from the mempool which spend
+    // from that root -- almost as though they were spending coinbases
+    // which are no longer valid to spend due to coinbase maturity.
+    LOCK(cs);
+    std::list<CTransaction> transactionsToRemove;
+    for (indexed_transaction_set::const_iterator it = mapTx.begin(); it != mapTx.end(); it++) {
+        const CTransaction& tx = it->GetTx();
+        if (!tx.IsShieldedTx()) continue;
+        for (const auto& sd : tx.sapData->vShieldedSpend) {
+            if (sd.anchor == invalidRoot) {
+                transactionsToRemove.push_back(tx);
+                break;
+            }
+        }
+    }
+    for (const CTransaction& tx : transactionsToRemove) {
+        std::list<CTransactionRef> removed;
+        remove(tx, removed, true);
+    }
+}
+
 void CTxMemPool::removeConflicts(const CTransaction& tx, std::list<CTransactionRef>& removed)
 {
     // Remove transactions which depend on inputs of tx, recursively
diff --git a/src/txmempool.h b/src/txmempool.h
@@ -479,6 +479,7 @@ class CTxMemPool
     bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, setEntries &setAncestors, bool fCurrentEstimate = true);
     void remove(const CTransaction& tx, std::list<CTransactionRef>& removed, bool fRecursive = false);
     void removeForReorg(const CCoinsViewCache* pcoins, unsigned int nMemPoolHeight, int flags);
+    void removeWithAnchor(const uint256& invalidRoot);
     void removeConflicts(const CTransaction& tx, std::list<CTransactionRef>& removed);
     void removeForBlock(const std::vector<CTransactionRef>& vtx, unsigned int nBlockHeight, std::list<CTransactionRef>& conflicts, bool fCurrentEstimate = true);
     void clear();
diff --git a/src/validation.cpp b/src/validation.cpp
@@ -1959,6 +1959,7 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
     if (!ReadBlockFromDisk(block, pindexDelete))
         return AbortNode(state, "Failed to read block");
     // Apply the block atomically to the chain state.
+    const uint256& saplingAnchorBeforeDisconnect = pcoinsTip->GetBestAnchor();
     int64_t nStart = GetTimeMicros();
     {
         CCoinsViewCache view(pcoinsTip);
@@ -1967,6 +1968,7 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
         assert(view.Flush());
     }
     LogPrint(BCLog::BENCH, "- Disconnect block: %.2fms\n", (GetTimeMicros() - nStart) * 0.001);
+    const uint256& saplingAnchorAfterDisconnect = pcoinsTip->GetBestAnchor();
     // Write the chain state to disk, if necessary.
     if (!FlushStateToDisk(state, FLUSH_STATE_ALWAYS))
         return false;
@@ -1996,6 +1998,12 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
     } else {
         mnodeman.UncacheBlockHash(pindexDelete);
     }
+    // Evict from mempool if the anchor changes
+    if (saplingAnchorBeforeDisconnect != saplingAnchorAfterDisconnect) {
+        // The anchor may not change between block disconnects,
+        // in which case we don't want to evict from the mempool yet!
+        mempool.removeWithAnchor(saplingAnchorBeforeDisconnect);
+    }
     // Update chainActive and related variables.
     UpdateTip(pindexDelete->pprev);
     // Let wallets know transactions went from 1-confirmed to
