src/checkpoints.cpp

   1 // Copyright (c) 2009-2012 The Bitcoin developers
   2 // Distributed under the MIT/X11 software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #include <boost/assign/list_of.hpp> // for 'map_list_of()'
   6 #include <boost/foreach.hpp>
   7
   8 #include "checkpoints.h"
   9
  10 #include "db.h"
  11 #include "main.h"
  12 #include "uint256.h"
  13
  14 namespace Checkpoints
  15 {
  16     struct Checkpoint
  17     {
  18         uint256 hashCheckPoint;
  19         unsigned int nTime;
  20     };
  21
  22     typedef std::map<int, Checkpoint> MapCheckpoints;
  23
  24     Checkpoint initCheckpoint(uint256 hashCheckPoint, unsigned int nTime)
  25     {
  26         return {hashCheckPoint, nTime};
  27     }
  28
  29     //
  30     // What makes a good checkpoint block?
  31     // + Is surrounded by blocks with reasonable timestamps
  32     //   (no blocks before with a timestamp after, none after with
  33     //    timestamp before)
  34     // + Contains no strange transactions
  35     //
  36     static MapCheckpoints mapCheckpoints =
  37         boost::assign::map_list_of
  38         ( 0, initCheckpoint(hashGenesisBlock, 1360105017) )
  39         ( 9690, initCheckpoint(uint256("0x00000000026561450859c46868099e0df6068a538f038cb18988fd8d47dcdaf5"), 1362791423) )
  40         ( 13560, initCheckpoint(uint256("0xa1591a0fcbf11f282d671581edb9f0aadcd06fee69761081e0a3245914c13729"), 1364674052) )
  41         ( 37092, initCheckpoint(uint256("0x0000000000a38c2f98556f46793b453e92d8fab2d31c0b93fd08bcf78e56099d"), 1376677203) )
  42     ;
  43
  44     // TestNet has no checkpoints
  45     static MapCheckpoints mapCheckpointsTestnet =
  46         boost::assign::map_list_of
  47         ( 0, initCheckpoint(hashGenesisBlockTestNet, 1360105017) )
  48         ;
  49
  50     bool CheckHardened(int nHeight, const uint256& hash)
  51     {
  52         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  53
  54         MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
  55         if (i == checkpoints.end()) return true;
  56         return hash == i->second.hashCheckPoint;
  57     }
  58
  59     int GetTotalBlocksEstimate()
  60     {
  61         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  62
  63         return checkpoints.rbegin()->first;
  64     }
  65
  66     int GetLastCheckpointTime()
  67     {
  68         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  69
  70         return checkpoints.rbegin()->second.nTime;
  71     }
  72
  73     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  74     {
  75         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  76
  77         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
  78         {
  79             const uint256& hash = i.second.hashCheckPoint;
  80             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  81             if (t != mapBlockIndex.end())
  82                 return t->second;
  83         }
  84         return NULL;
  85     }
  86
  87     // ppcoin: synchronized checkpoint (centrally broadcasted)
  88     uint256 hashSyncCheckpoint = 0;
  89     uint256 hashPendingCheckpoint = 0;
  90     CSyncCheckpoint checkpointMessage;
  91     CSyncCheckpoint checkpointMessagePending;
  92     uint256 hashInvalidCheckpoint = 0;
  93     CCriticalSection cs_hashSyncCheckpoint;
  94
  95     // ppcoin: get last synchronized checkpoint
  96     CBlockIndex* GetLastSyncCheckpoint()
  97     {
  98         LOCK(cs_hashSyncCheckpoint);
  99         if (!mapBlockIndex.count(hashSyncCheckpoint))
 100             error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
 101         else
 102             return mapBlockIndex[hashSyncCheckpoint];
 103         return NULL;
 104     }
 105
 106     // ppcoin: only descendant of current sync-checkpoint is allowed
 107     bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
 108     {
 109         if (!mapBlockIndex.count(hashSyncCheckpoint))
 110             return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
 111         if (!mapBlockIndex.count(hashCheckpoint))
 112             return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
 113
 114         CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
 115         CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
 116
 117         if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
 118         {
 119             // Received an older checkpoint, trace back from current checkpoint
 120             // to the same height of the received checkpoint to verify
 121             // that current checkpoint should be a descendant block
 122             CBlockIndex* pindex = pindexSyncCheckpoint;
 123             while (pindex->nHeight > pindexCheckpointRecv->nHeight)
 124                 if (!(pindex = pindex->pprev))
 125                     return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
 126             if (pindex->GetBlockHash() != hashCheckpoint)
 127             {
 128                 hashInvalidCheckpoint = hashCheckpoint;
 129                 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 130             }
 131             return false; // ignore older checkpoint
 132         }
 133
 134         // Received checkpoint should be a descendant block of the current
 135         // checkpoint. Trace back to the same height of current checkpoint
 136         // to verify.
 137         CBlockIndex* pindex = pindexCheckpointRecv;
 138         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
 139             if (!(pindex = pindex->pprev))
 140                 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
 141         if (pindex->GetBlockHash() != hashSyncCheckpoint)
 142         {
 143             hashInvalidCheckpoint = hashCheckpoint;
 144             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 145         }
 146         return true;
 147     }
 148
 149     bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
 150     {
 151         CTxDB txdb;
 152         txdb.TxnBegin();
 153         if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
 154         {
 155             txdb.TxnAbort();
 156             return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 157         }
 158         if (!txdb.TxnCommit())
 159             return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 160         txdb.Close();
 161
 162         Checkpoints::hashSyncCheckpoint = hashCheckpoint;
 163         return true;
 164     }
 165
 166     bool AcceptPendingSyncCheckpoint()
 167     {
 168         LOCK(cs_hashSyncCheckpoint);
 169         if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 170         {
 171             if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 172             {
 173                 hashPendingCheckpoint = 0;
 174                 checkpointMessagePending.SetNull();
 175                 return false;
 176             }
 177
 178             CTxDB txdb;
 179             CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 180             if (!pindexCheckpoint->IsInMainChain())
 181             {
 182                 CBlock block;
 183                 if (!block.ReadFromDisk(pindexCheckpoint))
 184                     return error("AcceptPendingSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 185                 if (!block.SetBestChain(txdb, pindexCheckpoint))
 186                 {
 187                     hashInvalidCheckpoint = hashPendingCheckpoint;
 188                     return error("AcceptPendingSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 189                 }
 190             }
 191             txdb.Close();
 192
 193             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 194                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 195             hashPendingCheckpoint = 0;
 196             checkpointMessage = checkpointMessagePending;
 197             checkpointMessagePending.SetNull();
 198             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 199             // relay the checkpoint
 200             if (!checkpointMessage.IsNull())
 201             {
 202                 BOOST_FOREACH(CNode* pnode, vNodes)
 203                     checkpointMessage.RelayTo(pnode);
 204             }
 205             return true;
 206         }
 207         return false;
 208     }
 209
 210     // Automatically select a suitable sync-checkpoint
 211     uint256 AutoSelectSyncCheckpoint()
 212     {
 213         // Proof-of-work blocks are immediately checkpointed
 214         // to defend against 51% attack which rejects other miners block
 215
 216         // Select the last proof-of-work block
 217         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 218         // Search forward for a block within max span and maturity window
 219         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + std::min(6, nCoinbaseMaturity - 20) <= pindexBest->nHeight))
 220             pindex = pindex->pnext;
 221         return pindex->GetBlockHash();
 222     }
 223
 224     // Check against synchronized checkpoint
 225     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 226     {
 227         if (fTestNet) return true; // Testnet has no checkpoints
 228         int nHeight = pindexPrev->nHeight + 1;
 229
 230         LOCK(cs_hashSyncCheckpoint);
 231         // sync-checkpoint should always be accepted block
 232         assert(mapBlockIndex.count(hashSyncCheckpoint));
 233         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 234
 235         if (nHeight > pindexSync->nHeight)
 236         {
 237             // trace back to same height as sync-checkpoint
 238             const CBlockIndex* pindex = pindexPrev;
 239             while (pindex->nHeight > pindexSync->nHeight)
 240                 if (!(pindex = pindex->pprev))
 241                     return error("CheckSync: pprev null - block index structure failure");
 242             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 243                 return false; // only descendant of sync-checkpoint can pass check
 244         }
 245         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 246             return false; // same height with sync-checkpoint
 247         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 248             return false; // lower height than sync-checkpoint
 249         return true;
 250     }
 251
 252     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 253     {
 254         LOCK(cs_hashSyncCheckpoint);
 255         if (hashPendingCheckpoint == 0)
 256             return false;
 257         if (hashBlock == hashPendingCheckpoint)
 258             return true;
 259         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 260             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 261             return true;
 262         return false;
 263     }
 264
 265     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 266     bool ResetSyncCheckpoint()
 267     {
 268         LOCK(cs_hashSyncCheckpoint);
 269         const uint256& hash = mapCheckpoints.rbegin()->second.hashCheckPoint;
 270         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 271         {
 272             // checkpoint block accepted but not yet in main chain
 273             printf("ResetSyncCheckpoint: SetBestChain to hardened checkpoint %s\n", hash.ToString().c_str());
 274             CTxDB txdb;
 275             CBlock block;
 276             if (!block.ReadFromDisk(mapBlockIndex[hash]))
 277                 return error("ResetSyncCheckpoint: ReadFromDisk failed for hardened checkpoint %s", hash.ToString().c_str());
 278             if (!block.SetBestChain(txdb, mapBlockIndex[hash]))
 279             {
 280                 return error("ResetSyncCheckpoint: SetBestChain failed for hardened checkpoint %s", hash.ToString().c_str());
 281             }
 282             txdb.Close();
 283         }
 284         else if(!mapBlockIndex.count(hash))
 285         {
 286             // checkpoint block not yet accepted
 287             hashPendingCheckpoint = hash;
 288             checkpointMessagePending.SetNull();
 289             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 290         }
 291
 292         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 293         {
 294             const uint256& hash = i.second.hashCheckPoint;
 295             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 296             {
 297                 if (!WriteSyncCheckpoint(hash))
 298                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 299                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 300                 return true;
 301             }
 302         }
 303
 304         return false;
 305     }
 306
 307     void AskForPendingSyncCheckpoint(CNode* pfrom)
 308     {
 309         LOCK(cs_hashSyncCheckpoint);
 310         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 311             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 312     }
 313
 314     bool SetCheckpointPrivKey(std::string strPrivKey)
 315     {
 316         // Test signing a sync-checkpoint with genesis block
 317         CSyncCheckpoint checkpoint;
 318         checkpoint.hashCheckpoint = !fTestNet ? hashGenesisBlock : hashGenesisBlockTestNet;
 319         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 320         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 321         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 322
 323         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 324         CKey key;
 325         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 326         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 327             return false;
 328
 329         // Test signing successful, proceed
 330         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 331         return true;
 332     }
 333
 334     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 335     {
 336         CSyncCheckpoint checkpoint;
 337         checkpoint.hashCheckpoint = hashCheckpoint;
 338         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 339         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 340         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 341
 342         if (CSyncCheckpoint::strMasterPrivKey.empty())
 343             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 344         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 345         CKey key;
 346         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 347         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 348             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 349
 350         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 351         {
 352             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 353             return false;
 354         }
 355
 356         // Relay checkpoint
 357         {
 358             LOCK(cs_vNodes);
 359             BOOST_FOREACH(CNode* pnode, vNodes)
 360                 checkpoint.RelayTo(pnode);
 361         }
 362         return true;
 363     }
 364
 365     // Is the sync-checkpoint outside maturity window?
 366     bool IsMatureSyncCheckpoint()
 367     {
 368         LOCK(cs_hashSyncCheckpoint);
 369         // sync-checkpoint should always be accepted block
 370         assert(mapBlockIndex.count(hashSyncCheckpoint));
 371         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 372         return (nBestHeight >= pindexSync->nHeight + nCoinbaseMaturity ||
 373                 pindexSync->GetBlockTime() + nStakeMinAge < GetAdjustedTime());
 374     }
 375
 376     // Is the sync-checkpoint too old?
 377     bool IsSyncCheckpointTooOld(unsigned int nSeconds)
 378     {
 379         LOCK(cs_hashSyncCheckpoint);
 380         // sync-checkpoint should always be accepted block
 381         assert(mapBlockIndex.count(hashSyncCheckpoint));
 382         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 383         return (pindexSync->GetBlockTime() + nSeconds < GetAdjustedTime());
 384     }
 385 }
 386
 387 // ppcoin: sync-checkpoint master key
 388 const std::string CSyncCheckpoint::strMasterPubKey = "04a51b735f816de4ec3f891d5b38bbc91e1f7245c7c08d17990760b86b4d8fc3910a850ffecf73bfa8886f01739a0c4c4322201282d07b6e48ce931cc92af94850";
 389
 390 std::string CSyncCheckpoint::strMasterPrivKey = "";
 391
 392 // ppcoin: verify signature of sync-checkpoint message
 393 bool CSyncCheckpoint::CheckSignature()
 394 {
 395     CKey key;
 396     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 397         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 398     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 399         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 400
 401     // Now unserialize the data
 402     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 403     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 404     return true;
 405 }
 406
 407 // ppcoin: process synchronized checkpoint
 408 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 409 {
 410     if (!CheckSignature())
 411         return false;
 412
 413     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 414     if (!mapBlockIndex.count(hashCheckpoint))
 415     {
 416         // We haven't received the checkpoint chain, keep the checkpoint as pending
 417         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 418         Checkpoints::checkpointMessagePending = *this;
 419         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 420         // Ask this guy to fill in what we're missing
 421         if (pfrom)
 422         {
 423             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 424             // ask directly as well in case rejected earlier by duplicate
 425             // proof-of-stake because getblocks may not get it this time
 426             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 427         }
 428         return false;
 429     }
 430
 431     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 432         return false;
 433
 434     CTxDB txdb;
 435     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 436     if (!pindexCheckpoint->IsInMainChain())
 437     {
 438         // checkpoint chain received but not yet main chain
 439         CBlock block;
 440         if (!block.ReadFromDisk(pindexCheckpoint))
 441             return error("ProcessSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 442         if (!block.SetBestChain(txdb, pindexCheckpoint))
 443         {
 444             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 445             return error("ProcessSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 446         }
 447     }
 448     txdb.Close();
 449
 450     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 451         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 452     Checkpoints::checkpointMessage = *this;
 453     Checkpoints::hashPendingCheckpoint = 0;
 454     Checkpoints::checkpointMessagePending.SetNull();
 455     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 456     return true;
 457 }