Fix "Spent Stake" vulnerability

Author: Limitless-VIP

configure.ac

@@ -1,11 +1,11 @@
 dnl require autoconf 2.60 (AS_ECHO/AS_ECHO_N)
 AC_PREREQ([2.60])
 define(_CLIENT_VERSION_MAJOR, 2)
-define(_CLIENT_VERSION_MINOR, 1)
+define(_CLIENT_VERSION_MINOR, 2)
 define(_CLIENT_VERSION_REVISION, 0)
 define(_CLIENT_VERSION_BUILD, 0)
 define(_CLIENT_VERSION_IS_RELEASE, true)
-define(_COPYRIGHT_YEAR, 2017)
+define(_COPYRIGHT_YEAR, 2019)
 AC_INIT([TittieCoin Core],[_CLIENT_VERSION_MAJOR._CLIENT_VERSION_MINOR._CLIENT_VERSION_REVISION],[www.tittiecoin.com],[tittiecoin])
 AC_CONFIG_SRCDIR([src/main.cpp])
 AC_CONFIG_HEADERS([src/config/tittiecoin-config.h])

src/clientversion.h

@@ -15,7 +15,7 @@
 
 //! These need to be macros, as clientversion.cpp's and tittiecoin*-res.rc's voodoo requires it
 #define CLIENT_VERSION_MAJOR 2
-#define CLIENT_VERSION_MINOR 1
+#define CLIENT_VERSION_MINOR 2
 #define CLIENT_VERSION_REVISION 0
 #define CLIENT_VERSION_BUILD 0
 

src/main.cpp

@@ -53,6 +53,7 @@ CCriticalSection cs_main;
 
 BlockMap mapBlockIndex;
 map<uint256, uint256> mapProofOfStake;
+map<COutPoint, int> mapStakeSpent;
 set<pair<COutPoint, unsigned int> > setStakeSeen;
 map<unsigned int, unsigned int> mapHashedBlocks;
 CChain chainActive;
@@ -2004,6 +2005,8 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
                 if (coins->vout.size() < out.n + 1)
                     coins->vout.resize(out.n + 1);
                 coins->vout[out.n] = undo.txout;
+				// erase the spent input
+		mapStakeSpent.erase(out);
             }
         }
     }
@@ -2235,6 +2238,33 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
         if (!pblocktree->WriteTxIndex(vPos))
             return state.Abort("Failed to write transaction index");
 
+		
+		
+
+    // add new entries
+    for (const CTransaction tx: block.vtx) {
+        if (tx.IsCoinBase())
+            continue;
+        for (const CTxIn in: tx.vin) {
+            LogPrint("map", "mapStakeSpent: Insert %s | %u\n", in.prevout.ToString(), pindex->nHeight);
+            mapStakeSpent.insert(std::make_pair(in.prevout, pindex->nHeight));
+        }
+    }
+
+
+    // delete old entries
+    for (auto it = mapStakeSpent.begin(); it != mapStakeSpent.end();) {
+        if (it->second < pindex->nHeight - Params().MaxReorganizationDepth()) {
+            LogPrint("map", "mapStakeSpent: Erase %s | %u\n", it->first.ToString(), it->second);
+            it = mapStakeSpent.erase(it);
+        }
+        else {
+            it++;
+        }
+    }
+
+
+
     // add this block to the view's block chain
     view.SetBestBlock(pindex->GetBlockHash());
 
@@ -3338,6 +3368,57 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
 
     int nHeight = pindex->nHeight;
 
+	
+	if (block.IsProofOfStake()) {
+        LOCK(cs_main);
+
+        CCoinsViewCache coins(pcoinsTip);
+
+        if (!coins.HaveInputs(block.vtx[1])) {
+            // the inputs are spent at the chain tip so we should look at the recently spent outputs
+
+            for (CTxIn in : block.vtx[1].vin) {
+                auto it = mapStakeSpent.find(in.prevout);
+                if (it == mapStakeSpent.end()) {
+                    return false;
+                }
+                if (it->second <= pindexPrev->nHeight) {
+                    return false;
+                }
+            }
+        }
+
+        // if this is on a fork
+        if (!chainActive.Contains(pindexPrev) && pindexPrev != NULL) {
+            // start at the block we're adding on to
+            CBlockIndex *last = pindexPrev;
+
+            // while that block is not on the main chain
+            while (!chainActive.Contains(last) && pindexPrev != NULL) {
+                CBlock bl;
+                ReadBlockFromDisk(bl, last);
+                // loop through every spent input from said block
+                for (CTransaction t : bl.vtx) {
+                    for (CTxIn in: t.vin) {
+                        // loop through every spent input in the staking transaction of the new block
+                        for (CTxIn stakeIn : block.vtx[1].vin) {
+                            // if they spend the same input
+                            if (stakeIn.prevout == in.prevout) {
+                                // reject the block
+                                return false;
+                            }
+                        }
+                    }
+                }
+
+
+                // go to the parent block
+                last = pindexPrev->pprev;
+            }
+        }
+    }   
+	
+	
     // Write block to history file
     try {
         unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);