1 // Copyright (c) 2009-2012 The Bitcoin developers
2 // Copyright (c) 2011-2012 The PPCoin developers
3 // Distributed under the MIT/X11 software license, see the accompanying
4 // file COPYING 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>
9 #include "checkpoints.h"
17 typedef std::map<int, uint256> MapCheckpoints; // hardened checkpoints
20 // What makes a good checkpoint block?
21 // + Is surrounded by blocks with reasonable timestamps
22 // (no blocks before with a timestamp after, none after with
24 // + Contains no strange transactions
26 static MapCheckpoints mapCheckpoints =
27 boost::assign::map_list_of
28 ( 0, hashGenesisBlockOfficial )
29 ; // ppcoin: no checkpoint yet; to be created in future releases
31 bool CheckHardened(int nHeight, const uint256& hash)
33 if (fTestNet) return true; // Testnet has no checkpoints
35 MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
36 if (i == mapCheckpoints.end()) return true;
37 return hash == i->second;
40 int GetTotalBlocksEstimate()
42 if (fTestNet) return 0;
44 return mapCheckpoints.rbegin()->first;
47 CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
50 std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hashGenesisBlock);
51 if (t != mapBlockIndex.end())
56 BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
58 const uint256& hash = i.second;
59 std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
60 if (t != mapBlockIndex.end())
66 // ppcoin: synchronized checkpoint (centrally broadcasted)
67 uint256 hashSyncCheckpoint = 0;
68 uint256 hashPendingCheckpoint = 0;
69 CSyncCheckpoint checkpointMessage;
70 CSyncCheckpoint checkpointMessagePending;
71 uint256 hashInvalidCheckpoint = 0;
72 CCriticalSection cs_hashSyncCheckpoint;
74 // ppcoin: get last synchronized checkpoint
75 CBlockIndex* GetLastSyncCheckpoint()
77 LOCK(cs_hashSyncCheckpoint);
78 if (!mapBlockIndex.count(hashSyncCheckpoint))
79 error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
81 return mapBlockIndex[hashSyncCheckpoint];
85 // ppcoin: only descendant of current sync-checkpoint is allowed
86 bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
88 if (!mapBlockIndex.count(hashSyncCheckpoint))
89 return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
90 if (!mapBlockIndex.count(hashCheckpoint))
91 return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
93 CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
94 CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
96 if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
98 // Received an older checkpoint, trace back from current checkpoint
99 // to the same height of the received checkpoint to verify
100 // that current checkpoint should be a descendant block
101 CBlockIndex* pindex = pindexSyncCheckpoint;
102 while (pindex->nHeight > pindexCheckpointRecv->nHeight)
103 if (!(pindex = pindex->pprev))
104 return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
105 if (pindex->GetBlockHash() != hashCheckpoint)
107 hashInvalidCheckpoint = hashCheckpoint;
108 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
110 return false; // ignore older checkpoint
113 // Received checkpoint should be a descendant block of the current
114 // checkpoint. Trace back to the same height of current checkpoint
116 CBlockIndex* pindex = pindexCheckpointRecv;
117 while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
118 if (!(pindex = pindex->pprev))
119 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
120 if (pindex->GetBlockHash() != hashSyncCheckpoint)
122 hashInvalidCheckpoint = hashCheckpoint;
123 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
128 bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
132 if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
135 return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
137 if (!txdb.TxnCommit())
138 return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
141 Checkpoints::hashSyncCheckpoint = hashCheckpoint;
145 bool AcceptPendingSyncCheckpoint()
147 LOCK(cs_hashSyncCheckpoint);
148 if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
150 if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
152 hashPendingCheckpoint = 0;
153 checkpointMessagePending.SetNull();
158 CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
159 if (!pindexCheckpoint->IsInMainChain())
162 if (!Reorganize(txdb, pindexCheckpoint))
165 hashInvalidCheckpoint = hashPendingCheckpoint;
166 return error("AcceptPendingSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
171 if (!WriteSyncCheckpoint(hashPendingCheckpoint))
172 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
173 hashPendingCheckpoint = 0;
174 checkpointMessage = checkpointMessagePending;
175 checkpointMessagePending.SetNull();
176 printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
177 // relay the checkpoint
178 if (!checkpointMessage.IsNull())
180 BOOST_FOREACH(CNode* pnode, vNodes)
181 checkpointMessage.RelayTo(pnode);
188 // Automatically select a suitable sync-checkpoint
189 uint256 AutoSelectSyncCheckpoint()
191 // Proof-of-work blocks are immediately checkpointed
192 // to defend against 51% attack which rejects other miners block
194 // Select the last proof-of-work block
195 const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
196 // Search forward for a block within max span and maturity window
197 while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + COINBASE_MATURITY - 20 <= pindexBest->nHeight))
198 pindex = pindex->pnext;
199 return pindex->GetBlockHash();
202 // Check against synchronized checkpoint
203 bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
205 if (fTestNet) return true; // Testnet has no checkpoints
206 int nHeight = pindexPrev->nHeight + 1;
208 LOCK(cs_hashSyncCheckpoint);
209 // sync-checkpoint should always be accepted block
210 assert(mapBlockIndex.count(hashSyncCheckpoint));
211 const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
213 if (nHeight > pindexSync->nHeight)
215 // trace back to same height as sync-checkpoint
216 const CBlockIndex* pindex = pindexPrev;
217 while (pindex->nHeight > pindexSync->nHeight)
218 if (!(pindex = pindex->pprev))
219 return error("CheckSync: pprev null - block index structure failure");
220 if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
221 return false; // only descendant of sync-checkpoint can pass check
223 if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
224 return false; // same height with sync-checkpoint
225 if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
226 return false; // lower height than sync-checkpoint
230 bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
232 LOCK(cs_hashSyncCheckpoint);
233 if (hashPendingCheckpoint == 0)
235 if (hashBlock == hashPendingCheckpoint)
237 if (mapOrphanBlocks.count(hashPendingCheckpoint)
238 && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
243 // ppcoin: reset synchronized checkpoint to last hardened checkpoint
244 bool ResetSyncCheckpoint()
246 LOCK(cs_hashSyncCheckpoint);
247 const uint256& hash = mapCheckpoints.rbegin()->second;
248 if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
250 // checkpoint block accepted but not yet in main chain
251 printf("ResetSyncCheckpoint: Reorganize to hardened checkpoint %s\n", hash.ToString().c_str());
254 if (!Reorganize(txdb, mapBlockIndex[hash]))
257 return error("ResetSyncCheckpoint: Reorganize failed for hardened checkpoint %s", hash.ToString().c_str());
261 else if(!mapBlockIndex.count(hash))
263 // checkpoint block not yet accepted
264 hashPendingCheckpoint = hash;
265 checkpointMessagePending.SetNull();
266 printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
269 BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
271 const uint256& hash = i.second;
272 if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
274 if (!WriteSyncCheckpoint(hash))
275 return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
276 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
284 void AskForPendingSyncCheckpoint(CNode* pfrom)
286 LOCK(cs_hashSyncCheckpoint);
287 if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
288 pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
291 bool SetCheckpointPrivKey(std::string strPrivKey)
293 // Test signing a sync-checkpoint with genesis block
294 CSyncCheckpoint checkpoint;
295 checkpoint.hashCheckpoint = hashGenesisBlock;
296 CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
297 sMsg << (CUnsignedSyncCheckpoint)checkpoint;
298 checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
300 std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
302 key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
303 if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
306 // Test signing successful, proceed
307 CSyncCheckpoint::strMasterPrivKey = strPrivKey;
311 bool SendSyncCheckpoint(uint256 hashCheckpoint)
313 CSyncCheckpoint checkpoint;
314 checkpoint.hashCheckpoint = hashCheckpoint;
315 CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
316 sMsg << (CUnsignedSyncCheckpoint)checkpoint;
317 checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
319 if (CSyncCheckpoint::strMasterPrivKey.empty())
320 return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
321 std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
323 key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
324 if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
325 return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
327 if(!checkpoint.ProcessSyncCheckpoint(NULL))
329 printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
336 BOOST_FOREACH(CNode* pnode, vNodes)
337 checkpoint.RelayTo(pnode);
342 // Is the sync-checkpoint outside maturity window?
343 bool IsMatureSyncCheckpoint()
345 LOCK(cs_hashSyncCheckpoint);
346 // sync-checkpoint should always be accepted block
347 assert(mapBlockIndex.count(hashSyncCheckpoint));
348 const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
349 return (nBestHeight >= pindexSync->nHeight + COINBASE_MATURITY);
353 // ppcoin: sync-checkpoint master key
354 const std::string CSyncCheckpoint::strMasterPubKey = "0424f20205e5da98ba632bbd278a11a6499585f62bfb2c782377ef59f0251daab8085fc31471bcb8180bc75ed0fa41bb50c7c084511d54015a3a5241d645c7268a";
356 std::string CSyncCheckpoint::strMasterPrivKey = "";
358 // ppcoin: verify signature of sync-checkpoint message
359 bool CSyncCheckpoint::CheckSignature()
362 if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
363 return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
364 if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
365 return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
367 // Now unserialize the data
368 CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
369 sMsg >> *(CUnsignedSyncCheckpoint*)this;
373 // ppcoin: process synchronized checkpoint
374 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
376 if (!CheckSignature())
379 LOCK(Checkpoints::cs_hashSyncCheckpoint);
380 if (!mapBlockIndex.count(hashCheckpoint))
382 // We haven't received the checkpoint chain, keep the checkpoint as pending
383 Checkpoints::hashPendingCheckpoint = hashCheckpoint;
384 Checkpoints::checkpointMessagePending = *this;
385 printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
386 // Ask this guy to fill in what we're missing
389 pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
390 // ask directly as well in case rejected earlier by duplicate
391 // proof-of-stake because getblocks may not get it this time
392 pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
397 if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
401 CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
402 if (!pindexCheckpoint->IsInMainChain())
404 // checkpoint chain received but not yet main chain
406 if (!Reorganize(txdb, pindexCheckpoint))
409 Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
410 return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
415 if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
416 return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
417 Checkpoints::checkpointMessage = *this;
418 Checkpoints::hashPendingCheckpoint = 0;
419 Checkpoints::checkpointMessagePending.SetNull();
420 printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());