From 2461aba1ac4e0673ed0568713b48e4bb37c8b041 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 3 Aug 2013 13:08:34 +0200
Subject: [PATCH] Mempool consistency check

---
 src/chainparams.h |  4 ++++
 src/init.cpp      |  1 +
 src/main.cpp      | 45 +++++++++++++++++++++++++++++++++++++++++++++
 src/main.h        |  2 ++
 4 files changed, 52 insertions(+)

diff --git a/src/chainparams.h b/src/chainparams.h
index 572712b58..2592ad1b1 100644
--- a/src/chainparams.h
+++ b/src/chainparams.h
@@ -99,4 +99,8 @@ inline bool TestNet() {
     return Params().NetworkID() == CChainParams::TESTNET;
 }
 
+inline bool RegTest() {
+    return Params().NetworkID() == CChainParams::REGTEST;
+}
+
 #endif
diff --git a/src/init.cpp b/src/init.cpp
index 09871c012..9f3d52641 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -424,6 +424,7 @@ bool AppInit2(boost::thread_group& threadGroup)
 
     fDebug = GetBoolArg("-debug", false);
     fBenchmark = GetBoolArg("-benchmark", false);
+    mempool.fChecks = GetBoolArg("-checkmempool", RegTest());
 
     // -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
     nScriptCheckThreads = GetArg("-par", 0);
diff --git a/src/main.cpp b/src/main.cpp
index 4c568245e..2ccd5131d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1014,6 +1014,45 @@ void CTxMemPool::clear()
     ++nTransactionsUpdated;
 }
 
+bool CTxMemPool::fChecks = false;
+
+void CTxMemPool::check(CCoinsViewCache *pcoins) const
+{
+    if (!fChecks)
+        return;
+
+    printf("Checking mempool with %u transactions and %u inputs\n", (unsigned int)mapTx.size(), (unsigned int)mapNextTx.size());
+
+    LOCK(cs);
+    for (std::map<uint256, CTransaction>::const_iterator it = mapTx.begin(); it != mapTx.end(); it++) {
+        unsigned int i = 0;
+        BOOST_FOREACH(const CTxIn &txin, it->second.vin) {
+            // Check that every mempool transaction's inputs refer to available coins, or other mempool tx's.
+            std::map<uint256, CTransaction>::const_iterator it2 = mapTx.find(txin.prevout.hash);
+            if (it2 != mapTx.end()) {
+                assert(it2->second.vout.size() > txin.prevout.n && !it2->second.vout[txin.prevout.n].IsNull());
+            } else {
+                CCoins &coins = pcoins->GetCoins(txin.prevout.hash);
+                assert(coins.IsAvailable(txin.prevout.n));
+            }
+            // Check whether its inputs are marked in mapNextTx.
+            std::map<COutPoint, CInPoint>::const_iterator it3 = mapNextTx.find(txin.prevout);
+            assert(it3 != mapNextTx.end());
+            assert(it3->second.ptx == &it->second);
+            assert(it3->second.n == i);
+            i++;
+        }
+    }
+    for (std::map<COutPoint, CInPoint>::const_iterator it = mapNextTx.begin(); it != mapNextTx.end(); it++) {
+        uint256 hash = it->second.ptx->GetHash();
+        std::map<uint256, CTransaction>::const_iterator it2 = mapTx.find(hash);
+        assert(it2 != mapTx.end());
+        assert(&it2->second == it->second.ptx);
+        assert(it2->second.vin.size() > it->second.n);
+        assert(it->first == it->second.ptx->vin[it->second.n].prevout);
+    }
+}
+
 void CTxMemPool::queryHashes(std::vector<uint256>& vtxid)
 {
     vtxid.clear();
@@ -1970,6 +2009,8 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
 
 bool SetBestChain(CValidationState &state, CBlockIndex* pindexNew)
 {
+    mempool.check(pcoinsTip);
+
     // All modifications to the coin state will be done in this cache.
     // Only when all have succeeded, we push it to pcoinsTip.
     CCoinsViewCache view(*pcoinsTip, true);
@@ -2093,6 +2134,8 @@ bool SetBestChain(CValidationState &state, CBlockIndex* pindexNew)
         mempool.removeConflicts(tx);
     }
 
+    mempool.check(pcoinsTip);
+
     // Update best block in wallet (so we can detect restored wallets)
     if ((pindexNew->nHeight % 20160) == 0 || (!fIsInitialDownload && (pindexNew->nHeight % 144) == 0))
     {
@@ -3678,6 +3721,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         CValidationState state;
         if (mempool.accept(state, tx, true, &fMissingInputs))
         {
+            mempool.check(pcoinsTip);
             RelayTransaction(tx, inv.hash);
             mapAlreadyAskedFor.erase(inv);
             vWorkQueue.push_back(inv.hash);
@@ -3713,6 +3757,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
                         vEraseQueue.push_back(orphanHash);
                         printf("   removed orphan tx %s\n", orphanHash.ToString().c_str());
                     }
+                    mempool.check(pcoinsTip);
                 }
             }
 
diff --git a/src/main.h b/src/main.h
index ea86a2bcc..a690a2bc9 100644
--- a/src/main.h
+++ b/src/main.h
@@ -1077,6 +1077,7 @@ public:
 class CTxMemPool
 {
 public:
+    static bool fChecks;
     mutable CCriticalSection cs;
     std::map<uint256, CTransaction> mapTx;
     std::map<COutPoint, CInPoint> mapNextTx;
@@ -1088,6 +1089,7 @@ public:
     void clear();
     void queryHashes(std::vector<uint256>& vtxid);
     void pruneSpent(const uint256& hash, CCoins &coins);
+    void check(CCoinsViewCache *pcoins) const;
 
     unsigned long size()
     {