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 bool CheckHardened(int nHeight, const uint256& hash)
30 if (fTestNet) return true; // Testnet has no checkpoints
32 MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
33 if (i == mapCheckpoints.end()) return true;
34 return hash == i->second;
37 int GetTotalBlocksEstimate()
39 if (fTestNet) return 0;
41 return mapCheckpoints.rbegin()->first;
44 CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
46 if (fTestNet) return NULL;
49 BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
51 const uint256& hash = i.second;
52 std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
53 if (t != mapBlockIndex.end())
59 // ppcoin: synchronized checkpoint (centrally broadcasted)
60 uint256 hashSyncCheckpoint;
61 CCriticalSection cs_hashSyncCheckpoint;
63 bool AcceptNewSyncCheckpoint(uint256 hashCheckpoint)
67 bool CSyncCheckpoint::ProcessSyncCheckpoint()
69 if (!CheckSignature())
72 CRITICAL_BLOCK(cs_hashSyncCheckpoint)
73 hashSyncCheckpoint = this->hashCheckpoint;
76 // ppcoin: automatic checkpoint (represented by height of checkpoint)
77 int nAutoCheckpoint = 0;
78 int nBranchPoint = 0; // branch point to alternative branch
80 // ppcoin: check automatic checkpoint
82 // - All ancestors (including the block itself) have block index already
83 // - The immediate ancestor in main chain must not have height less than
85 bool CheckAuto(const CBlockIndex *pindex)
89 if (pindex->IsInMainChain())
91 if (pindex->nHeight >= nAutoCheckpoint)
95 nBranchPoint = pindex->nHeight;
96 return error("Checkpoints: new block on alternative branch at height=%d before auto checkpoint at height=%d", pindex->nHeight, nAutoCheckpoint);
100 pindex = pindex->pprev;
102 return error("Checkpoints: failed to find any ancestor on main chain for the new block - internal error");
105 // ppcoin: get next chain checkpoint
106 int GetNextChainCheckpoint(const CBlockIndex *pindexLast)
109 CBigNum bnTargetMax = 0; // max target of all blocks since checkpoint
110 CBigNum bnTargetMin = 0; // min target of all candidate checkpoints
111 int nMinTargetHeight = 0; // min target height of candidate checkpoints
112 int nCheckpointMin = 0; // minimum candidate checkpoint
113 int nCheckpointMax = 0; // maximum candidate checkpoint
114 int nDepth = pindexLast->nHeight - pindexLast->nCheckpoint;
115 const CBlockIndex *pindex = pindexLast;
116 while (nDepth >= 0 && pindex)
118 bnTarget.SetCompact(pindex->nBits);
119 if (bnTarget > bnTargetMax)
120 bnTargetMax = bnTarget;
121 if (nCheckpointMax > 0 && bnTarget < bnTargetMin)
123 bnTargetMin = bnTarget;
124 nMinTargetHeight = pindex->nHeight;
126 if (nCheckpointMax == 0 && pindexLast->GetBlockTime() - pindex->GetBlockTime() > AUTO_CHECKPOINT_MIN_SPAN)
128 nCheckpointMax = pindex->nHeight;
129 bnTargetMin.SetCompact(pindex->nBits);
130 nMinTargetHeight = pindex->nHeight;
132 if (pindexLast->GetBlockTime() - pindex->GetBlockTime() < AUTO_CHECKPOINT_MAX_SPAN)
133 nCheckpointMin = pindex->nHeight;
134 pindex = pindex->pprev;
138 assert (nDepth == -1); // arrive at chain checkpoint now
140 printf("Checkpoints: min=%d max=%d tminheight=%d tmin=0x%08x tmax=0x%08x\n",
141 nCheckpointMin, nCheckpointMax, nMinTargetHeight,
142 bnTargetMin.GetCompact(), bnTargetMax.GetCompact());
143 if (nCheckpointMax == 0) // checkpoint stays if max candidate not found
144 return pindexLast->nCheckpoint;
146 if (bnTargetMin * 100 > bnTargetMax * 90)
147 return nCheckpointMax;
148 if (bnTarget * 100 > bnTargetMax * 90)
149 return nMinTargetHeight;
151 return nCheckpointMin;
154 // ppcoin: get next auto checkpoint from the new chain checkpoint
155 int GetNextAutoCheckpoint(int nCheckpoint)
157 return (std::max(nAutoCheckpoint, nCheckpoint));
160 // ppcoin: advance to next automatic checkpoint
161 void AdvanceAutoCheckpoint(int nCheckpoint)
163 nAutoCheckpoint = GetNextAutoCheckpoint(nCheckpoint);
164 printf("Checkpoints: auto checkpoint now at height=%d\n", nAutoCheckpoint);
167 // ppcoin: reset auto checkpoint
168 bool ResetAutoCheckpoint(int nCheckpoint)
170 if (nCheckpoint <= 0 || nCheckpoint > nBestHeight)
171 return error("ResetAutoCheckpoint() : new checkpoint invalid");
172 if (nCheckpoint >= nAutoCheckpoint)
173 return error("ResetAutoCheckpoint() : new checkpoint not earlier than current auto checkpoint");
176 if (!txdb.WriteAutoCheckpoint(nCheckpoint, true))
177 return error("ResetAutoCheckpoint() : database write failed");
178 if (!txdb.TxnCommit())
179 return error("ResetAutoCheckpoint() : database commit failed");
180 nAutoCheckpoint = nCheckpoint;
181 nBranchPoint = 0; // clear branch point
183 // clear ban list to accept alternative branches
184 CRITICAL_BLOCK(cs_vNodes)
186 BOOST_FOREACH(CNode* pnode, vNodes)
187 pnode->ClearBanned();