Make sure that new stake modifier meets fixed generation interval.

[novacoin.git] / src / kernel.cpp

diff --git a/src/kernel.cpp b/src/kernel.cpp
index 959bd10..2484c3c 100644 (file)
--- a/src/kernel.cpp
+++ b/src/kernel.cpp
@@ -12,6 +12,15 @@ using namespace std;
 extern int nStakeMaxAge;
 extern int nStakeTargetSpacing;
 
+// Protocol switch time for fixed kernel modifier interval
+unsigned int nModifierSwitchTime  = 1413763200;    // Mon, 20 Oct 2014 00:00:00 GMT
+unsigned int nModifierTestSwitchTime = 1397520000; // Tue, 15 Apr 2014 00:00:00 GMT
+
+// Note: user must upgrade before the protocol switch deadline, otherwise it's required to
+//   re-download the blockchain. The timestamp of upgrade is recorded in the blockchain 
+//   database.
+unsigned int nModifierUpgradeTime = 0;
+
 typedef std::map<int, unsigned int> MapModifierCheckpoints;
 
 // Hard checkpoints of stake modifiers to ensure they are deterministic
@@ -23,6 +32,9 @@ static std::map<int, unsigned int> mapStakeModifierCheckpoints =
         ( 37092, 0xd230afccu )
         ( 44200, 0x05370164u )
         ( 65000, 0xc8e7be6au )
+        ( 68600, 0x73a8cc4cu )
+        ( 92161, 0xe21a911au )
+        ( 98661, 0xd20c44d4u )
     ;
 
 // Hard checkpoints of stake modifiers to ensure they are deterministic (testNet)
@@ -31,6 +43,24 @@ static std::map<int, unsigned int> mapStakeModifierCheckpointsTestNet =
         ( 0, 0x0e00670bu )
     ;
 
+// Whether the given block is subject to new modifier protocol
+bool IsFixedModifierInterval(unsigned int nTimeBlock)
+{
+    return (nTimeBlock >= (fTestNet? nModifierTestSwitchTime : nModifierSwitchTime));
+}
+
+// Get time weight
+int64 GetWeight(int64 nIntervalBeginning, int64 nIntervalEnd)
+{
+    // Kernel hash weight starts from 0 at the 30-day min age
+    // this change increases active coins participating the hash and helps
+    // to secure the network when proof-of-stake difficulty is low
+    //
+    // Maximum TimeWeight is 90 days.
+
+    return min(nIntervalEnd - nIntervalBeginning - nStakeMinAge, (int64)nStakeMaxAge);
+}
+
 // Get the last stake modifier and its generation time from a given block
 static bool GetLastStakeModifier(const CBlockIndex* pindex, uint64& nStakeModifier, int64& nModifierTime)
 {
@@ -120,15 +150,17 @@ static bool SelectBlockFromCandidates(vector<pair<int64, uint256> >& vSortedByTi
 // block. This is to make it difficult for an attacker to gain control of
 // additional bits in the stake modifier, even after generating a chain of
 // blocks.
-bool ComputeNextStakeModifier(const CBlockIndex* pindexPrev, uint64& nStakeModifier, bool& fGeneratedStakeModifier)
+bool ComputeNextStakeModifier(const CBlockIndex* pindexCurrent, uint64& nStakeModifier, bool& fGeneratedStakeModifier)
 {
     nStakeModifier = 0;
     fGeneratedStakeModifier = false;
+    const CBlockIndex* pindexPrev = pindexCurrent->pprev;
     if (!pindexPrev)
     {
         fGeneratedStakeModifier = true;
         return true;  // genesis block's modifier is 0
     }
+
     // First find current stake modifier and its generation block time
     // if it's not old enough, return the same stake modifier
     int64 nModifierTime = 0;
@@ -136,10 +168,35 @@ bool ComputeNextStakeModifier(const CBlockIndex* pindexPrev, uint64& nStakeModif
         return error("ComputeNextStakeModifier: unable to get last modifier");
     if (fDebug)
     {
-        printf("ComputeNextStakeModifier: prev modifier=0x%016"PRI64x" time=%s\n", nStakeModifier, DateTimeStrFormat(nModifierTime).c_str());
+        printf("ComputeNextStakeModifier: prev modifier=0x%016"PRI64x" time=%s epoch=%u\n", nStakeModifier, DateTimeStrFormat(nModifierTime).c_str(), (unsigned int)nModifierTime);
     }
     if (nModifierTime / nModifierInterval >= pindexPrev->GetBlockTime() / nModifierInterval)
+    {
+        if (fDebug)
+        {
+            printf("ComputeNextStakeModifier: no new interval keep current modifier: pindexPrev nHeight=%d nTime=%u\n", pindexPrev->nHeight, (unsigned int)pindexPrev->GetBlockTime());
+        }
         return true;
+    }
+    if (nModifierTime / nModifierInterval >= pindexCurrent->GetBlockTime() / nModifierInterval)
+    {
+        // fixed interval protocol requires current block timestamp also be in a different modifier interval
+        if (IsFixedModifierInterval(pindexCurrent->nTime))
+        {
+            if (fDebug)
+            {
+                printf("ComputeNextStakeModifier: no new interval keep current modifier: pindexCurrent nHeight=%d nTime=%u\n", pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
+            }
+            return true;
+        }
+        else
+        {
+            if (fDebug)
+            {
+                printf("ComputeNextStakeModifier: old modifier at block %s not meeting fixed modifier interval: pindexCurrent nHeight=%d nTime=%u\n", pindexCurrent->GetBlockHash().ToString().c_str(), pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
+            }
+        }
+    }
 
     // Sort candidate blocks by timestamp
     vector<pair<int64, uint256> > vSortedByTimestamp;
@@ -275,17 +332,9 @@ bool CheckStakeKernelHash(unsigned int nBits, const CBlock& blockFrom, unsigned
     bnTargetPerCoinDay.SetCompact(nBits);
     int64 nValueIn = txPrev.vout[prevout.n].nValue;
 
-    int64 nTimeWeight;
     uint256 hashBlockFrom = blockFrom.GetHash();
 
-    // Kernel hash weight starts from 0 at the 30-day min age
-    // this change increases active coins participating the hash and helps
-    // to secure the network when proof-of-stake difficulty is low
-    //
-    // Maximum TimeWeight is 90 days.
-    nTimeWeight = min((int64)nTimeTx - txPrev.nTime - nStakeMinAge, (int64)nStakeMaxAge);
-
-    CBigNum bnCoinDayWeight = CBigNum(nValueIn) * nTimeWeight / COIN / (24 * 60 * 60);
+    CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64)txPrev.nTime, (int64)nTimeTx) / COIN / (24 * 60 * 60);
     targetProofOfStake = (bnCoinDayWeight * bnTargetPerCoinDay).getuint256();
 
     // Calculate hash
@@ -347,10 +396,6 @@ bool CheckProofOfStake(const CTransaction& tx, unsigned int nBits, uint256& hash
     if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
         return tx.DoS(1, error("CheckProofOfStake() : INFO: read txPrev failed"));  // previous transaction not in main chain, may occur during initial download
 
-#ifndef USE_LEVELDB
-    txdb.Close();
-#endif
-
     // Verify signature
     if (!VerifySignature(txPrev, tx, 0, true, 0))
         return tx.DoS(100, error("CheckProofOfStake() : VerifySignature failed on coinstake %s", tx.GetHash().ToString().c_str()));
@@ -366,13 +411,6 @@ bool CheckProofOfStake(const CTransaction& tx, unsigned int nBits, uint256& hash
     return true;
 }
 
-// Check whether the coinstake timestamp meets protocol
-bool CheckCoinStakeTimestamp(int64 nTimeBlock, int64 nTimeTx)
-{
-    // v0.3 protocol
-    return (nTimeBlock == nTimeTx);
-}
-
 // Get stake modifier checksum
 unsigned int GetStakeModifierChecksum(const CBlockIndex* pindex)
 {