New validation rule is coming into force since 20 December 2015.

[novacoin.git] / src / main.cpp

diff --git a/src/main.cpp b/src/main.cpp
index 9ff24e4..f6adb17 100644 (file)
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -511,6 +511,10 @@ bool CTransaction::CheckTransaction() const
         return DoS(10, error("CTransaction::CheckTransaction() : vin empty"));
     if (vout.empty())
         return DoS(10, error("CTransaction::CheckTransaction() : vout empty"));
+    // Time (prevent mempool memory exhaustion attack)
+    // Comes into force since 20 December 2015.
+    if (nTime > 1450569600 && nTime > FutureDrift(GetAdjustedTime()))
+        return DoS(10, error("CTransaction::CheckTransaction() : timestamp is too far into the future"));
     // Size limits
     if (::GetSerializeSize(*this, SER_NETWORK, PROTOCOL_VERSION) > MAX_BLOCK_SIZE)
         return DoS(100, error("CTransaction::CheckTransaction() : size limits failed"));
@@ -2335,10 +2339,19 @@ bool CBlock::AcceptBlock()
     if (nBits != GetNextTargetRequired(pindexPrev, IsProofOfStake()))
         return DoS(100, error("AcceptBlock() : incorrect %s", IsProofOfWork() ? "proof-of-work" : "proof-of-stake"));
 
+    int64_t nMedianTimePast = pindexPrev->GetMedianTimePast();
+    int nMaxOffset = 12 * 3600; // 12 hours
+    if (pindexPrev->nTime < 1450569600)
+        nMaxOffset = 7 * 86400; // One week until 20 Dec, 2015
+
     // Check timestamp against prev
-    if (GetBlockTime() <= pindexPrev->GetMedianTimePast() || FutureDrift(GetBlockTime()) < pindexPrev->GetBlockTime())
+    if (GetBlockTime() <= nMedianTimePast || FutureDrift(GetBlockTime()) < pindexPrev->GetBlockTime())
         return error("AcceptBlock() : block's timestamp is too early");
 
+    // Don't accept blocks with future timestamps
+    if (pindexPrev->nHeight > 1 && nMedianTimePast  + nMaxOffset < GetBlockTime())
+        return error("AcceptBlock() : block's timestamp is too far in the future");
+
     // Check that all transactions are finalized
     BOOST_FOREACH(const CTransaction& tx, vtx)
         if (!tx.IsFinal(nHeight, GetBlockTime()))
@@ -2675,7 +2688,7 @@ static filesystem::path BlockFilePath(unsigned int nFile)
 
 FILE* OpenBlockFile(unsigned int nFile, unsigned int nBlockPos, const char* pszMode)
 {
-    if ((nFile < 1) || (nFile == (unsigned int) -1))
+    if ((nFile < 1) || (nFile == std::numeric_limits<uint32_t>::max()))
         return NULL;
     FILE* file = fopen(BlockFilePath(nFile).string().c_str(), pszMode);
     if (!file)
@@ -2942,7 +2955,7 @@ bool LoadExternalBlockFile(FILE* fileIn)
         try {
             CAutoFile blkdat(fileIn, SER_DISK, CLIENT_VERSION);
             unsigned int nPos = 0;
-            while (nPos != (unsigned int)-1 && blkdat.good() && !fRequestShutdown)
+            while (nPos != std::numeric_limits<uint32_t>::max() && blkdat.good() && !fRequestShutdown)
             {
                 unsigned char pchData[65536];
                 do {
@@ -2950,7 +2963,7 @@ bool LoadExternalBlockFile(FILE* fileIn)
                     int nRead = fread(pchData, 1, sizeof(pchData), blkdat);
                     if (nRead <= 8)
                     {
-                        nPos = (unsigned int)-1;
+                        nPos = std::numeric_limits<uint32_t>::max();
                         break;
                     }
                     void* nFind = memchr(pchData, pchMessageStart[0], nRead+1-sizeof(pchMessageStart));
@@ -2966,7 +2979,7 @@ bool LoadExternalBlockFile(FILE* fileIn)
                     else
                         nPos += sizeof(pchData) - sizeof(pchMessageStart) + 1;
                 } while(!fRequestShutdown);
-                if (nPos == (unsigned int)-1)
+                if (nPos == std::numeric_limits<uint32_t>::max())
                     break;
                 fseek(blkdat, nPos, SEEK_SET);
                 unsigned int nSize;
@@ -3335,7 +3348,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         }
 
         // find last block in inv vector
-        unsigned int nLastBlock = (unsigned int)(-1);
+        unsigned int nLastBlock = std::numeric_limits<uint32_t>::max();
         for (unsigned int nInv = 0; nInv < vInv.size(); nInv++) {
             if (vInv[vInv.size() - 1 - nInv].type == MSG_BLOCK) {
                 nLastBlock = vInv.size() - 1 - nInv;
@@ -3619,7 +3632,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
     }
 
 
-    else if (strCommand == "getaddr")
+    // This asymmetric behavior for inbound and outbound connections was introduced
+    // to prevent a fingerprinting attack: an attacker can send specific fake addresses
+    // to users' AddrMan and later request them by sending getaddr messages. 
+    // Making users (which are behind NAT and can only make outgoing connections) ignore 
+    // getaddr message mitigates the attack.
+    else if ((strCommand == "getaddr") && (pfrom->fInbound))
     {
         // Don't return addresses older than nCutOff timestamp
         int64_t nCutOff = GetTime() - (nNodeLifespan * nOneDay);
@@ -4070,4 +4088,4 @@ public:
 
         // orphan transactions
     }
-} instance_of_cmaincleanup;
\ No newline at end of file
+} instance_of_cmaincleanup;