// Copyright (c) 2011 The Bitcoin developers
+// Copyright (c) 2011-2012 The PPCoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
namespace Checkpoints
{
- typedef std::map<int, uint256> MapCheckpoints;
+ typedef std::map<int, uint256> MapCheckpoints; // hardened checkpoints
//
// What makes a good checkpoint block?
( 0, hashGenesisBlock )
; // ppcoin: no checkpoint yet; to be created in future releases
- bool CheckBlock(int nHeight, const uint256& hash)
+ bool CheckHardened(int nHeight, const uint256& hash)
{
if (fTestNet) return true; // Testnet has no checkpoints
}
return NULL;
}
+
+ // ppcoin: synchronized checkpoint (centrally broadcasted)
+ uint256 hashSyncCheckpoint;
+ CSyncCheckpoint checkpointMessage;
+ CSyncCheckpoint checkpointMessagePending;
+ uint256 hashInvalidCheckpoint = 0;
+ CCriticalSection cs_hashSyncCheckpoint;
+
+ // ppcoin: get last synchronized checkpoint
+ CBlockIndex* GetLastSyncCheckpoint()
+ {
+ CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+ {
+ if (!mapBlockIndex.count(hashSyncCheckpoint))
+ error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
+ else
+ return mapBlockIndex[hashSyncCheckpoint];
+ }
+ return NULL;
+ }
+
+ // ppcoin: only descendant of current sync-checkpoint is allowed
+ bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
+ {
+ if (!mapBlockIndex.count(hashSyncCheckpoint))
+ return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
+ if (!mapBlockIndex.count(hashCheckpoint))
+ return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
+
+ CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
+ CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
+
+ if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
+ {
+ // Received an older checkpoint, trace back from current checkpoint
+ // to the same height of the received checkpoint to verify
+ // that current checkpoint should be a descendant block
+ CBlockIndex* pindex = pindexSyncCheckpoint;
+ while (pindex->nHeight > pindexCheckpointRecv->nHeight)
+ if (!(pindex = pindex->pprev))
+ return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
+ if (pindex->GetBlockHash() != hashCheckpoint)
+ {
+ hashInvalidCheckpoint = hashCheckpoint;
+ return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
+ }
+ return false; // ignore older checkpoint
+ }
+
+ // Received checkpoint should be a descendant block of the current
+ // checkpoint. Trace back to the same height of current checkpoint
+ // to verify.
+ CBlockIndex* pindex = pindexCheckpointRecv;
+ while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
+ if (!(pindex = pindex->pprev))
+ return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
+ if (pindex->GetBlockHash() != hashSyncCheckpoint)
+ {
+ hashInvalidCheckpoint = hashCheckpoint;
+ return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
+ }
+ return true;
+ }
+
+ bool AcceptPendingSyncCheckpoint()
+ {
+ CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+ {
+ if ((!checkpointMessagePending.IsNull()) && mapBlockIndex.count(checkpointMessagePending.hashCheckpoint))
+ {
+ if (!ValidateSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
+ {
+ checkpointMessagePending.SetNull();
+ return false;
+ }
+
+ CTxDB txdb;
+ CBlockIndex* pindexCheckpoint = mapBlockIndex[checkpointMessagePending.hashCheckpoint];
+ if (!pindexCheckpoint->IsInMainChain())
+ {
+ txdb.TxnBegin();
+ if (!Reorganize(txdb, pindexCheckpoint))
+ {
+ txdb.TxnAbort();
+ hashInvalidCheckpoint = checkpointMessagePending.hashCheckpoint;
+ return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", checkpointMessagePending.hashCheckpoint.ToString().c_str());
+ }
+ }
+
+ txdb.TxnBegin();
+ if (!txdb.WriteSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
+ {
+ txdb.TxnAbort();
+ return error("AcceptPendingSyncCheckpoint() : failed to write to db sync checkpoint %s\n", checkpointMessagePending.hashCheckpoint.ToString().c_str());
+ }
+ if (!txdb.TxnCommit())
+ return error("AcceptPendingSyncCheckpoint() : failed to commit to db sync checkpoint %s\n", checkpointMessagePending.hashCheckpoint.ToString().c_str());
+ txdb.Close();
+
+ hashSyncCheckpoint = checkpointMessagePending.hashCheckpoint;
+ checkpointMessage = checkpointMessagePending;
+ checkpointMessagePending.SetNull();
+ printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
+ // relay the checkpoint
+ CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+ BOOST_FOREACH(CNode* pnode, vNodes)
+ checkpointMessage.RelayTo(pnode);
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ uint256 AutoSelectSyncCheckpoint()
+ {
+ // select block roughly 8 hours ago
+ CBlockIndex *pindex = mapBlockIndex[hashSyncCheckpoint];
+ while (pindex->pnext && pindex->pnext->GetBlockTime() + AUTO_CHECKPOINT_MIN_SPAN <= GetAdjustedTime())
+ pindex = pindex->pnext;
+ return pindex->GetBlockHash();
+ }
+
+ // Check against synchronized checkpoint
+ bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
+ {
+ if (fTestNet) return true; // Testnet has no checkpoints
+ int nHeight = pindexPrev->nHeight + 1;
+
+ CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+ {
+ // sync-checkpoint should always be accepted block
+ assert(mapBlockIndex.count(hashSyncCheckpoint));
+ const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
+
+ if (nHeight > pindexSync->nHeight)
+ {
+ // trace back to same height as sync-checkpoint
+ const CBlockIndex* pindex = pindexPrev;
+ while (pindex->nHeight > pindexSync->nHeight)
+ if (!(pindex = pindex->pprev))
+ return error("CheckSync: pprev null - block index structure failure");
+ if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
+ return false; // only descendant of sync-checkpoint can pass check
+ }
+ if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
+ return false; // same height with sync-checkpoint
+ if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
+ return false; // lower height than sync-checkpoint
+ }
+ return true;
+ }
+
+ bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
+ {
+ CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+ {
+ if (checkpointMessagePending.IsNull())
+ return false;
+ if (hashBlock == checkpointMessagePending.hashCheckpoint)
+ return true;
+ if (mapOrphanBlocks.count(checkpointMessagePending.hashCheckpoint)
+ && hashBlock == WantedByOrphan(mapOrphanBlocks[checkpointMessagePending.hashCheckpoint]))
+ return true;
+ }
+ return false;
+ }
+
+ // ppcoin: automatic checkpoint (represented by height of checkpoint)
+ int nAutoCheckpoint = 0;
+ int nBranchPoint = 0; // branch point to alternative branch
+
+ // ppcoin: check automatic checkpoint
+ // To pass the check:
+ // - All ancestors (including the block itself) have block index already
+ // - The immediate ancestor in main chain must not have height less than
+ // checkpoint height
+ bool CheckAuto(const CBlockIndex *pindex)
+ {
+ while (pindex)
+ {
+ if (pindex->IsInMainChain())
+ {
+ if (pindex->nHeight >= nAutoCheckpoint)
+ return true;
+ else
+ {
+ nBranchPoint = pindex->nHeight;
+ return error("Checkpoints: new block on alternative branch at height=%d before auto checkpoint at height=%d", pindex->nHeight, nAutoCheckpoint);
+ }
+ }
+ else
+ pindex = pindex->pprev;
+ }
+ return error("Checkpoints: failed to find any ancestor on main chain for the new block - internal error");
+ }
+
+ // ppcoin: get next chain checkpoint
+ int GetNextChainCheckpoint(const CBlockIndex *pindexLast)
+ {
+ CBigNum bnTarget;
+ CBigNum bnTargetMax = 0; // max target of all blocks since checkpoint
+ CBigNum bnTargetMin = 0; // min target of all candidate checkpoints
+ int nMinTargetHeight = 0; // min target height of candidate checkpoints
+ int nCheckpointMin = 0; // minimum candidate checkpoint
+ int nCheckpointMax = 0; // maximum candidate checkpoint
+ int nDepth = pindexLast->nHeight - pindexLast->nCheckpoint;
+ const CBlockIndex *pindex = pindexLast;
+ while (nDepth >= 0 && pindex)
+ {
+ bnTarget.SetCompact(pindex->nBits);
+ if (bnTarget > bnTargetMax)
+ bnTargetMax = bnTarget;
+ if (nCheckpointMax > 0 && bnTarget < bnTargetMin)
+ {
+ bnTargetMin = bnTarget;
+ nMinTargetHeight = pindex->nHeight;
+ }
+ if (nCheckpointMax == 0 && pindexLast->GetBlockTime() - pindex->GetBlockTime() > AUTO_CHECKPOINT_MIN_SPAN)
+ {
+ nCheckpointMax = pindex->nHeight;
+ bnTargetMin.SetCompact(pindex->nBits);
+ nMinTargetHeight = pindex->nHeight;
+ }
+ if (pindexLast->GetBlockTime() - pindex->GetBlockTime() < AUTO_CHECKPOINT_MAX_SPAN)
+ nCheckpointMin = pindex->nHeight;
+ pindex = pindex->pprev;
+ nDepth--;
+ }
+
+ assert (nDepth == -1); // arrive at chain checkpoint now
+
+ printf("Checkpoints: min=%d max=%d tminheight=%d tmin=0x%08x tmax=0x%08x\n",
+ nCheckpointMin, nCheckpointMax, nMinTargetHeight,
+ bnTargetMin.GetCompact(), bnTargetMax.GetCompact());
+ if (nCheckpointMax == 0) // checkpoint stays if max candidate not found
+ return pindexLast->nCheckpoint;
+
+ if (bnTargetMin * 100 > bnTargetMax * 90)
+ return nCheckpointMax;
+ if (bnTarget * 100 > bnTargetMax * 90)
+ return nMinTargetHeight;
+ else
+ return nCheckpointMin;
+ }
+
+ // ppcoin: get next auto checkpoint from the new chain checkpoint
+ int GetNextAutoCheckpoint(int nCheckpoint)
+ {
+ return (std::max(nAutoCheckpoint, nCheckpoint));
+ }
+
+ // ppcoin: advance to next automatic checkpoint
+ void AdvanceAutoCheckpoint(int nCheckpoint)
+ {
+ nAutoCheckpoint = GetNextAutoCheckpoint(nCheckpoint);
+ printf("Checkpoints: auto checkpoint now at height=%d\n", nAutoCheckpoint);
+ }
+
+ // ppcoin: reset auto checkpoint
+ bool ResetAutoCheckpoint(int nCheckpoint)
+ {
+ if (nCheckpoint <= 0 || nCheckpoint > nBestHeight)
+ return error("ResetAutoCheckpoint() : new checkpoint invalid");
+ if (nCheckpoint >= nAutoCheckpoint)
+ return error("ResetAutoCheckpoint() : new checkpoint not earlier than current auto checkpoint");
+ CTxDB txdb;
+ txdb.TxnBegin();
+ if (!txdb.WriteAutoCheckpoint(nCheckpoint, true))
+ return error("ResetAutoCheckpoint() : database write failed");
+ if (!txdb.TxnCommit())
+ return error("ResetAutoCheckpoint() : database commit failed");
+ nAutoCheckpoint = nCheckpoint;
+ nBranchPoint = 0; // clear branch point
+
+ // clear ban list to accept alternative branches
+ CRITICAL_BLOCK(cs_vNodes)
+ {
+ BOOST_FOREACH(CNode* pnode, vNodes)
+ pnode->ClearBanned();
+ }
+
+ return true;
+ }
+}
+
+// ppcoin: sync-checkpoint master key
+const std::string CSyncCheckpoint::strMasterPubKey = "0424f20205e5da98ba632bbd278a11a6499585f62bfb2c782377ef59f0251daab8085fc31471bcb8180bc75ed0fa41bb50c7c084511d54015a3a5241d645c7268a";
+
+// ppcoin: verify signature of sync-checkpoint message
+bool CSyncCheckpoint::CheckSignature()
+{
+ CKey key;
+ if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
+ return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
+ if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
+ return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
+
+ // Now unserialize the data
+ CDataStream sMsg(vchMsg);
+ sMsg >> *(CUnsignedSyncCheckpoint*)this;
+ return true;
+}
+
+// ppcoin: process synchronized checkpoint
+bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
+{
+ if (!CheckSignature())
+ return false;
+
+ CRITICAL_BLOCK(Checkpoints::cs_hashSyncCheckpoint)
+ {
+ if (!mapBlockIndex.count(hashCheckpoint))
+ {
+ // We haven't received the checkpoint chain, keep the checkpoint as pending
+ Checkpoints::checkpointMessagePending = *this;
+ printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
+ // Ask this guy to fill in what we're missing
+ if (pfrom)
+ {
+ pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
+ // ask directly as well in case rejected earlier by duplicate
+ // proof-of-stake because getblocks may not get it this time
+ pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
+ }
+ return false;
+ }
+
+ if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
+ return false;
+
+ CTxDB txdb;
+ CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
+ if (!pindexCheckpoint->IsInMainChain())
+ {
+ // checkpoint chain received but not yet main chain
+ txdb.TxnBegin();
+ if (!Reorganize(txdb, pindexCheckpoint))
+ {
+ txdb.TxnAbort();
+ Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
+ return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
+ }
+ }
+
+ txdb.TxnBegin();
+ if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
+ {
+ txdb.TxnAbort();
+ return error("ProcessSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
+ }
+ if (!txdb.TxnCommit())
+ return error("ProcessSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
+ txdb.Close();
+
+ Checkpoints::hashSyncCheckpoint = hashCheckpoint;
+ Checkpoints::checkpointMessage = *this;
+ Checkpoints::checkpointMessagePending.SetNull();
+ printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
+ }
+ return true;
}
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