src/checkpoints.cpp

   1 // Copyright (c) 2009-2012 The Bitcoin developers
   2 // Copyright (c) 2011-2013 The PPCoin developers
   3 // Copyright (c) 2013 NovaCoin Developers
   4 // Distributed under the MIT/X11 software license, see the accompanying
   5 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   6
   7 #include <boost/assign/list_of.hpp> // for 'map_list_of()'
   8 #include <boost/foreach.hpp>
   9
  10 #include "checkpoints.h"
  11
  12 #include "db.h"
  13 #include "main.h"
  14 #include "uint256.h"
  15
  16 namespace Checkpoints
  17 {
  18     typedef std::map<int, uint256> MapCheckpoints;   // hardened checkpoints
  19
  20     //
  21     // What makes a good checkpoint block?
  22     // + Is surrounded by blocks with reasonable timestamps
  23     //   (no blocks before with a timestamp after, none after with
  24     //    timestamp before)
  25     // + Contains no strange transactions
  26     //
  27     static MapCheckpoints mapCheckpoints =
  28         boost::assign::map_list_of
  29         ( 0, hashGenesisBlockOfficial )
  30         ( 6000, uint256("0x000000000945e3c9d8e15df834e802521eb79f9ceb4191a27bdfadad4b777f4a"))
  31         ( 8700, uint256("0x00000000014270724837789c9a69859290f6bdee38556bc4561c21f17935a178"))
  32         ( 13560, uint256("0xa1591a0fcbf11f282d671581edb9f0aadcd06fee69761081e0a3245914c13729"))
  33         ( 14189, uint256("0x00000000020f76474d2522b19c7bfafc43ba6ecbabae54293bcd9546159c8c1d"))
  34         ;
  35
  36     bool CheckHardened(int nHeight, const uint256& hash)
  37     {
  38         if (fTestNet) return true; // Testnet has no checkpoints
  39
  40         MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
  41         if (i == mapCheckpoints.end()) return true;
  42         return hash == i->second;
  43     }
  44
  45     int GetTotalBlocksEstimate()
  46     {
  47         if (fTestNet) return 0;
  48
  49         return mapCheckpoints.rbegin()->first;
  50     }
  51
  52     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  53     {
  54         if (fTestNet) {
  55             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hashGenesisBlock);
  56             if (t != mapBlockIndex.end())
  57                 return t->second;
  58             return NULL;
  59         }
  60
  61         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
  62         {
  63             const uint256& hash = i.second;
  64             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  65             if (t != mapBlockIndex.end())
  66                 return t->second;
  67         }
  68         return NULL;
  69     }
  70
  71     // ppcoin: synchronized checkpoint (centrally broadcasted)
  72     uint256 hashSyncCheckpoint = 0;
  73     uint256 hashPendingCheckpoint = 0;
  74     CSyncCheckpoint checkpointMessage;
  75     CSyncCheckpoint checkpointMessagePending;
  76     uint256 hashInvalidCheckpoint = 0;
  77     CCriticalSection cs_hashSyncCheckpoint;
  78
  79     // ppcoin: get last synchronized checkpoint
  80     CBlockIndex* GetLastSyncCheckpoint()
  81     {
  82         LOCK(cs_hashSyncCheckpoint);
  83         if (!mapBlockIndex.count(hashSyncCheckpoint))
  84             error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  85         else
  86             return mapBlockIndex[hashSyncCheckpoint];
  87         return NULL;
  88     }
  89
  90     // ppcoin: only descendant of current sync-checkpoint is allowed
  91     bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
  92     {
  93         if (!mapBlockIndex.count(hashSyncCheckpoint))
  94             return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  95         if (!mapBlockIndex.count(hashCheckpoint))
  96             return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
  97
  98         CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
  99         CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
 100
 101         if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
 102         {
 103             // Received an older checkpoint, trace back from current checkpoint
 104             // to the same height of the received checkpoint to verify
 105             // that current checkpoint should be a descendant block
 106             CBlockIndex* pindex = pindexSyncCheckpoint;
 107             while (pindex->nHeight > pindexCheckpointRecv->nHeight)
 108                 if (!(pindex = pindex->pprev))
 109                     return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
 110             if (pindex->GetBlockHash() != hashCheckpoint)
 111             {
 112                 hashInvalidCheckpoint = hashCheckpoint;
 113                 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 114             }
 115             return false; // ignore older checkpoint
 116         }
 117
 118         // Received checkpoint should be a descendant block of the current
 119         // checkpoint. Trace back to the same height of current checkpoint
 120         // to verify.
 121         CBlockIndex* pindex = pindexCheckpointRecv;
 122         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
 123             if (!(pindex = pindex->pprev))
 124                 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
 125         if (pindex->GetBlockHash() != hashSyncCheckpoint)
 126         {
 127             hashInvalidCheckpoint = hashCheckpoint;
 128             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 129         }
 130         return true;
 131     }
 132
 133     bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
 134     {
 135         CTxDB txdb;
 136         txdb.TxnBegin();
 137         if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
 138         {
 139             txdb.TxnAbort();
 140             return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 141         }
 142         if (!txdb.TxnCommit())
 143             return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 144         txdb.Close();
 145
 146         Checkpoints::hashSyncCheckpoint = hashCheckpoint;
 147         return true;
 148     }
 149
 150     bool AcceptPendingSyncCheckpoint()
 151     {
 152         LOCK(cs_hashSyncCheckpoint);
 153         if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 154         {
 155             if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 156             {
 157                 hashPendingCheckpoint = 0;
 158                 checkpointMessagePending.SetNull();
 159                 return false;
 160             }
 161
 162             CTxDB txdb;
 163             CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 164             if (!pindexCheckpoint->IsInMainChain())
 165             {
 166                 CBlock block;
 167                 if (!block.ReadFromDisk(pindexCheckpoint))
 168                     return error("AcceptPendingSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 169                 if (!block.SetBestChain(txdb, pindexCheckpoint))
 170                 {
 171                     hashInvalidCheckpoint = hashPendingCheckpoint;
 172                     return error("AcceptPendingSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 173                 }
 174             }
 175             txdb.Close();
 176
 177             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 178                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 179             hashPendingCheckpoint = 0;
 180             checkpointMessage = checkpointMessagePending;
 181             checkpointMessagePending.SetNull();
 182             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 183             // relay the checkpoint
 184             if (!checkpointMessage.IsNull())
 185             {
 186                 BOOST_FOREACH(CNode* pnode, vNodes)
 187                     checkpointMessage.RelayTo(pnode);
 188             }
 189             return true;
 190         }
 191         return false;
 192     }
 193
 194     // Automatically select a suitable sync-checkpoint
 195     uint256 AutoSelectSyncCheckpoint()
 196     {
 197         // Proof-of-work blocks are immediately checkpointed
 198         // to defend against 51% attack which rejects other miners block
 199
 200         // Select the last proof-of-work block
 201         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 202         // Search forward for a block within max span and maturity window
 203         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + std::min(6, nCoinbaseMaturity - 20) <= pindexBest->nHeight))
 204             pindex = pindex->pnext;
 205         return pindex->GetBlockHash();
 206     }
 207
 208     // Check against synchronized checkpoint
 209     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 210     {
 211         if (fTestNet) return true; // Testnet has no checkpoints
 212         int nHeight = pindexPrev->nHeight + 1;
 213
 214         LOCK(cs_hashSyncCheckpoint);
 215         // sync-checkpoint should always be accepted block
 216         assert(mapBlockIndex.count(hashSyncCheckpoint));
 217         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 218
 219         if (nHeight > pindexSync->nHeight)
 220         {
 221             // trace back to same height as sync-checkpoint
 222             const CBlockIndex* pindex = pindexPrev;
 223             while (pindex->nHeight > pindexSync->nHeight)
 224                 if (!(pindex = pindex->pprev))
 225                     return error("CheckSync: pprev null - block index structure failure");
 226             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 227                 return false; // only descendant of sync-checkpoint can pass check
 228         }
 229         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 230             return false; // same height with sync-checkpoint
 231         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 232             return false; // lower height than sync-checkpoint
 233         return true;
 234     }
 235
 236     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 237     {
 238         LOCK(cs_hashSyncCheckpoint);
 239         if (hashPendingCheckpoint == 0)
 240             return false;
 241         if (hashBlock == hashPendingCheckpoint)
 242             return true;
 243         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 244             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 245             return true;
 246         return false;
 247     }
 248
 249     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 250     bool ResetSyncCheckpoint()
 251     {
 252         LOCK(cs_hashSyncCheckpoint);
 253         const uint256& hash = mapCheckpoints.rbegin()->second;
 254         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 255         {
 256             // checkpoint block accepted but not yet in main chain
 257             printf("ResetSyncCheckpoint: SetBestChain to hardened checkpoint %s\n", hash.ToString().c_str());
 258             CTxDB txdb;
 259             CBlock block;
 260             if (!block.ReadFromDisk(mapBlockIndex[hash]))
 261                 return error("ResetSyncCheckpoint: ReadFromDisk failed for hardened checkpoint %s", hash.ToString().c_str());
 262             if (!block.SetBestChain(txdb, mapBlockIndex[hash]))
 263             {
 264                 return error("ResetSyncCheckpoint: SetBestChain failed for hardened checkpoint %s", hash.ToString().c_str());
 265             }
 266             txdb.Close();
 267         }
 268         else if(!mapBlockIndex.count(hash))
 269         {
 270             // checkpoint block not yet accepted
 271             hashPendingCheckpoint = hash;
 272             checkpointMessagePending.SetNull();
 273             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 274         }
 275
 276         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 277         {
 278             const uint256& hash = i.second;
 279             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 280             {
 281                 if (!WriteSyncCheckpoint(hash))
 282                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 283                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 284                 return true;
 285             }
 286         }
 287
 288         return false;
 289     }
 290
 291     void AskForPendingSyncCheckpoint(CNode* pfrom)
 292     {
 293         LOCK(cs_hashSyncCheckpoint);
 294         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 295             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 296     }
 297
 298     bool SetCheckpointPrivKey(std::string strPrivKey)
 299     {
 300         // Test signing a sync-checkpoint with genesis block
 301         CSyncCheckpoint checkpoint;
 302         checkpoint.hashCheckpoint = hashGenesisBlock;
 303         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 304         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 305         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 306
 307         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 308         CKey key;
 309         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 310         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 311             return false;
 312
 313         // Test signing successful, proceed
 314         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 315         return true;
 316     }
 317
 318     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 319     {
 320         CSyncCheckpoint checkpoint;
 321         checkpoint.hashCheckpoint = hashCheckpoint;
 322         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 323         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 324         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 325
 326         if (CSyncCheckpoint::strMasterPrivKey.empty())
 327             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 328         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 329         CKey key;
 330         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 331         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 332             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 333
 334         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 335         {
 336             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 337             return false;
 338         }
 339
 340         // Relay checkpoint
 341         {
 342             LOCK(cs_vNodes);
 343             BOOST_FOREACH(CNode* pnode, vNodes)
 344                 checkpoint.RelayTo(pnode);
 345         }
 346         return true;
 347     }
 348
 349     // Is the sync-checkpoint outside maturity window?
 350     bool IsMatureSyncCheckpoint()
 351     {
 352         LOCK(cs_hashSyncCheckpoint);
 353         // sync-checkpoint should always be accepted block
 354         assert(mapBlockIndex.count(hashSyncCheckpoint));
 355         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 356         return (nBestHeight >= pindexSync->nHeight + nCoinbaseMaturity ||
 357                 pindexSync->GetBlockTime() + nStakeMinAge < GetAdjustedTime());
 358     }
 359
 360     // Is the sync-checkpoint too old?
 361     bool IsSyncCheckpointTooOld(unsigned int nSeconds)
 362     {
 363         LOCK(cs_hashSyncCheckpoint);
 364         // sync-checkpoint should always be accepted block
 365         assert(mapBlockIndex.count(hashSyncCheckpoint));
 366         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 367         return (pindexSync->GetBlockTime() + nSeconds < GetAdjustedTime());
 368     }
 369 }
 370
 371 // ppcoin: sync-checkpoint master key
 372 const std::string CSyncCheckpoint::strMasterPubKey = "04a51b735f816de4ec3f891d5b38bbc91e1f7245c7c08d17990760b86b4d8fc3910a850ffecf73bfa8886f01739a0c4c4322201282d07b6e48ce931cc92af94850";
 373
 374 std::string CSyncCheckpoint::strMasterPrivKey = "";
 375
 376 // ppcoin: verify signature of sync-checkpoint message
 377 bool CSyncCheckpoint::CheckSignature()
 378 {
 379     CKey key;
 380     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 381         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 382     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 383         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 384
 385     // Now unserialize the data
 386     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 387     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 388     return true;
 389 }
 390
 391 // ppcoin: process synchronized checkpoint
 392 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 393 {
 394     if (!CheckSignature())
 395         return false;
 396
 397     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 398     if (!mapBlockIndex.count(hashCheckpoint))
 399     {
 400         // We haven't received the checkpoint chain, keep the checkpoint as pending
 401         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 402         Checkpoints::checkpointMessagePending = *this;
 403         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 404         // Ask this guy to fill in what we're missing
 405         if (pfrom)
 406         {
 407             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 408             // ask directly as well in case rejected earlier by duplicate
 409             // proof-of-stake because getblocks may not get it this time
 410             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 411         }
 412         return false;
 413     }
 414
 415     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 416         return false;
 417
 418     CTxDB txdb;
 419     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 420     if (!pindexCheckpoint->IsInMainChain())
 421     {
 422         // checkpoint chain received but not yet main chain
 423         CBlock block;
 424         if (!block.ReadFromDisk(pindexCheckpoint))
 425             return error("ProcessSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 426         if (!block.SetBestChain(txdb, pindexCheckpoint))
 427         {
 428             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 429             return error("ProcessSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 430         }
 431     }
 432     txdb.Close();
 433
 434     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 435         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 436     Checkpoints::checkpointMessage = *this;
 437     Checkpoints::hashPendingCheckpoint = 0;
 438     Checkpoints::checkpointMessagePending.SetNull();
 439     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 440     return true;
 441 }