1 // Copyright (c) 2011 The Bitcoin developers
2 // Copyright (c) 2011-2012 The PPCoin developers
3 // Distributed under the MIT/X11 software license, see the accompanying
4 // file license.txt or http://www.opensource.org/licenses/mit-license.php.
6 #include <boost/assign/list_of.hpp> // for 'map_list_of()'
7 #include <boost/foreach.hpp>
10 #include "checkpoints.h"
14 typedef std::map<int, uint256> MapCheckpoints; // hardened checkpoints
17 // What makes a good checkpoint block?
18 // + Is surrounded by blocks with reasonable timestamps
19 // (no blocks before with a timestamp after, none after with
21 // + Contains no strange transactions
23 static MapCheckpoints mapCheckpoints =
24 boost::assign::map_list_of
25 ( 0, hashGenesisBlock )
26 ; // ppcoin: no checkpoint yet; to be created in future releases
28 // ppcoin: automatic checkpoint (represented by height of checkpoint)
29 int nAutoCheckpoint = 0;
30 int nBranchPoint = 0; // branch point to alternative branch
32 bool CheckHardened(int nHeight, const uint256& hash)
34 if (fTestNet) return true; // Testnet has no checkpoints
36 MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
37 if (i == mapCheckpoints.end()) return true;
38 return hash == i->second;
41 // ppcoin: check automatic checkpoint
43 // - All ancestors (including the block itself) have block index already
44 // - The immediate ancestor in main chain must not have height less than
46 bool CheckAuto(const CBlockIndex *pindex)
50 if (pindex->IsInMainChain())
52 if (pindex->nHeight >= nAutoCheckpoint)
56 nBranchPoint = pindex->nHeight;
57 return error("Checkpoints: new block on alternative branch at height=%d before auto checkpoint at height=%d", pindex->nHeight, nAutoCheckpoint);
61 pindex = pindex->pprev;
63 return error("Checkpoints: failed to find any ancestor on main chain for the new block - internal error");
66 // ppcoin: get next chain checkpoint
67 int GetNextChainCheckpoint(const CBlockIndex *pindexLast)
70 CBigNum bnTargetMax = 0; // max target of all blocks since checkpoint
71 CBigNum bnTargetMin = 0; // min target of all candidate checkpoints
72 int nMinTargetHeight = 0; // min target height of candidate checkpoints
73 int nCheckpointMin = 0; // minimum candidate checkpoint
74 int nCheckpointMax = 0; // maximum candidate checkpoint
75 int nDepth = pindexLast->nHeight - pindexLast->nCheckpoint;
76 const CBlockIndex *pindex = pindexLast;
77 while (nDepth >= 0 && pindex)
79 bnTarget.SetCompact(pindex->nBits);
80 if (bnTarget > bnTargetMax)
81 bnTargetMax = bnTarget;
82 if (nCheckpointMax > 0 && bnTarget < bnTargetMin)
84 bnTargetMin = bnTarget;
85 nMinTargetHeight = pindex->nHeight;
87 if (nCheckpointMax == 0 && pindexLast->GetBlockTime() - pindex->GetBlockTime() > AUTO_CHECKPOINT_MIN_SPAN)
89 nCheckpointMax = pindex->nHeight;
90 bnTargetMin.SetCompact(pindex->nBits);
91 nMinTargetHeight = pindex->nHeight;
93 if (pindexLast->GetBlockTime() - pindex->GetBlockTime() < AUTO_CHECKPOINT_MAX_SPAN)
94 nCheckpointMin = pindex->nHeight;
95 pindex = pindex->pprev;
99 assert (nDepth == -1); // arrive at chain checkpoint now
101 printf("Checkpoints: min=%d max=%d tminheight=%d tmin=0x%08x tmax=0x%08x\n",
102 nCheckpointMin, nCheckpointMax, nMinTargetHeight,
103 bnTargetMin.GetCompact(), bnTargetMax.GetCompact());
104 if (nCheckpointMax == 0) // checkpoint stays if max candidate not found
105 return pindexLast->nCheckpoint;
107 if (bnTargetMin * 100 > bnTargetMax * 90)
108 return nCheckpointMax;
109 if (bnTarget * 100 > bnTargetMax * 90)
110 return nMinTargetHeight;
112 return nCheckpointMin;
115 // ppcoin: get next auto checkpoint from the new chain checkpoint
116 int GetNextAutoCheckpoint(int nCheckpoint)
118 return (std::max(nAutoCheckpoint, nCheckpoint));
121 // ppcoin: advance to next automatic checkpoint
122 void AdvanceAutoCheckpoint(int nCheckpoint)
124 nAutoCheckpoint = GetNextAutoCheckpoint(nCheckpoint);
125 printf("Checkpoints: auto checkpoint now at height=%d\n", nAutoCheckpoint);
128 int GetTotalBlocksEstimate()
130 if (fTestNet) return 0;
132 return mapCheckpoints.rbegin()->first;
135 // ppcoin: reset auto checkpoint
136 bool ResetAutoCheckpoint(int nCheckpoint)
138 if (nCheckpoint <= 0 || nCheckpoint > nBestHeight)
139 return error("ResetAutoCheckpoint() : new checkpoint invalid");
140 if (nCheckpoint >= nAutoCheckpoint)
141 return error("ResetAutoCheckpoint() : new checkpoint not earlier than current auto checkpoint");
144 if (!txdb.WriteAutoCheckpoint(nCheckpoint, true))
145 return error("ResetAutoCheckpoint() : database write failed");
146 if (!txdb.TxnCommit())
147 return error("ResetAutoCheckpoint() : database commit failed");
148 nAutoCheckpoint = nCheckpoint;
149 nBranchPoint = 0; // clear branch point
151 // clear ban list to accept alternative branches
152 CRITICAL_BLOCK(cs_vNodes)
154 BOOST_FOREACH(CNode* pnode, vNodes)
155 pnode->ClearBanned();
161 CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
163 if (fTestNet) return NULL;
166 BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
168 const uint256& hash = i.second;
169 std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
170 if (t != mapBlockIndex.end())