// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
-#include "checkpoints.h"
-#include "uint256.h"
-#include "util.h"
-
#include <boost/assign/list_of.hpp> // for 'map_list_of()'
+#include <boost/foreach.hpp>
+
+#include "headers.h"
+#include "checkpoints.h"
namespace Checkpoints
{
typedef std::map<int, uint256> MapCheckpoints;
+ //
+ // What makes a good checkpoint block?
+ // + Is surrounded by blocks with reasonable timestamps
+ // (no blocks before with a timestamp after, none after with
+ // timestamp before)
+ // + Contains no strange transactions
+ //
static MapCheckpoints mapCheckpoints =
boost::assign::map_list_of
( 11111, uint256("0x0000000069e244f73d78e8fd29ba2fd2ed618bd6fa2ee92559f542fdb26e7c1d"))
int GetTotalBlocksEstimate()
{
- if (fTestNet) return 0; // Testnet has no checkpoints
+ if (fTestNet) return 0;
return mapCheckpoints.rbegin()->first;
}
+
+ CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
+ {
+ if (fTestNet) return NULL;
+
+ int64 nResult;
+ BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
+ {
+ const uint256& hash = i.second;
+ std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
+ if (t != mapBlockIndex.end())
+ return t->second;
+ }
+ return NULL;
+ }
}
#ifndef BITCOIN_CHECKPOINT_H
#define BITCOIN_CHECKPOINT_H
+#include <map>
+#include "util.h"
+
class uint256;
+class CBlockIndex;
//
// Block-chain checkpoints are compiled-in sanity checks.
// Return conservative estimate of total number of blocks, 0 if unknown
int GetTotalBlocksEstimate();
+
+ // Returns last CBlockIndex* in mapBlockIndex that is a checkpoint
+ CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex);
}
#endif
return nSubsidy + nFees;
}
+static const int64 nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+static const int64 nTargetSpacing = 10 * 60;
+static const int64 nInterval = nTargetTimespan / nTargetSpacing;
+
+//
+// minimum amount of work that could possibly be required nTime after
+// minimum work required was nBase
+//
+unsigned int ComputeMinWork(unsigned int nBase, int64 nTime)
+{
+ CBigNum bnResult;
+ bnResult.SetCompact(nBase);
+ while (nTime > 0 && bnResult < bnProofOfWorkLimit)
+ {
+ // Maximum 400% adjustment...
+ bnResult *= 4;
+ // ... in best-case exactly 4-times-normal target time
+ nTime -= nTargetTimespan*4;
+ }
+ if (bnResult > bnProofOfWorkLimit)
+ bnResult = bnProofOfWorkLimit;
+ return bnResult.GetCompact();
+}
+
unsigned int static GetNextWorkRequired(const CBlockIndex* pindexLast)
{
- const int64 nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
- const int64 nTargetSpacing = 10 * 60;
- const int64 nInterval = nTargetTimespan / nTargetSpacing;
// Genesis block
if (pindexLast == NULL)
if (!pblock->CheckBlock())
return error("ProcessBlock() : CheckBlock FAILED");
+ CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint(mapBlockIndex);
+ if (pcheckpoint && pblock->hashPrevBlock != hashBestChain)
+ {
+ // Extra checks to prevent "fill up memory by spamming with bogus blocks"
+ int64 deltaTime = pblock->GetBlockTime() - pcheckpoint->nTime;
+ if (deltaTime < 0)
+ {
+ return error("ProcessBlock() : block with timestamp before last checkpoint");
+ }
+ CBigNum bnNewBlock;
+ bnNewBlock.SetCompact(pblock->nBits);
+ CBigNum bnRequired;
+ bnRequired.SetCompact(ComputeMinWork(pcheckpoint->nBits, deltaTime));
+ if (bnNewBlock > bnRequired)
+ {
+ return error("ProcessBlock() : block with too little proof-of-work");
+ }
+ }
+
+
// If don't already have its previous block, shunt it off to holding area until we get it
if (!mapBlockIndex.count(pblock->hashPrevBlock))
{
void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1);
bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey);
bool CheckProofOfWork(uint256 hash, unsigned int nBits);
+unsigned int ComputeMinWork(unsigned int nBase, int64 nTime);
bool IsInitialBlockDownload();
std::string GetWarnings(std::string strFor);