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 "txdb.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         Checkpoint item;
  27         item.hashCheckPoint = hashCheckPoint;
  28         item.nTime = nTime;
  29
  30         return item;
  31     }
  32
  33     //
  34     // What makes a good checkpoint block?
  35     // + Is surrounded by blocks with reasonable timestamps
  36     //   (no blocks before with a timestamp after, none after with
  37     //    timestamp before)
  38     // + Contains no strange transactions
  39     //
  40     static MapCheckpoints mapCheckpoints =
  41         boost::assign::map_list_of
  42         ( 0, initCheckpoint(hashGenesisBlock, 1360105017) )
  43         ( 9690, initCheckpoint(uint256("0x00000000026561450859c46868099e0df6068a538f038cb18988fd8d47dcdaf5"), 1362791423) )
  44         ( 13560, initCheckpoint(uint256("0xa1591a0fcbf11f282d671581edb9f0aadcd06fee69761081e0a3245914c13729"), 1364674052) )
  45         ( 37092, initCheckpoint(uint256("0x0000000000a38c2f98556f46793b453e92d8fab2d31c0b93fd08bcf78e56099d"), 1376677203) )
  46     ;
  47
  48     // TestNet has no checkpoints
  49     static MapCheckpoints mapCheckpointsTestnet =
  50         boost::assign::map_list_of
  51         ( 0, initCheckpoint(hashGenesisBlockTestNet, 1360105017) )
  52         ;
  53
  54     bool CheckHardened(int nHeight, const uint256& hash)
  55     {
  56         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  57
  58         MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
  59         if (i == checkpoints.end()) return true;
  60         return hash == i->second.hashCheckPoint;
  61     }
  62
  63     int GetTotalBlocksEstimate()
  64     {
  65         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  66
  67         return checkpoints.rbegin()->first;
  68     }
  69
  70     int GetLastCheckpointTime()
  71     {
  72         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  73
  74         return checkpoints.rbegin()->second.nTime;
  75     }
  76
  77     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  78     {
  79         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  80
  81         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
  82         {
  83             const uint256& hash = i.second.hashCheckPoint;
  84             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  85             if (t != mapBlockIndex.end())
  86                 return t->second;
  87         }
  88         return NULL;
  89     }
  90
  91     // ppcoin: synchronized checkpoint (centrally broadcasted)
  92     uint256 hashSyncCheckpoint = 0;
  93     uint256 hashPendingCheckpoint = 0;
  94     CSyncCheckpoint checkpointMessage;
  95     CSyncCheckpoint checkpointMessagePending;
  96     uint256 hashInvalidCheckpoint = 0;
  97     CCriticalSection cs_hashSyncCheckpoint;
  98
  99     // ppcoin: get last synchronized checkpoint
 100     CBlockIndex* GetLastSyncCheckpoint()
 101     {
 102         LOCK(cs_hashSyncCheckpoint);
 103         if (!mapBlockIndex.count(hashSyncCheckpoint))
 104             error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
 105         else
 106             return mapBlockIndex[hashSyncCheckpoint];
 107         return NULL;
 108     }
 109
 110     // ppcoin: only descendant of current sync-checkpoint is allowed
 111     bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
 112     {
 113         if (!mapBlockIndex.count(hashSyncCheckpoint))
 114             return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
 115         if (!mapBlockIndex.count(hashCheckpoint))
 116             return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
 117
 118         CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
 119         CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
 120
 121         if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
 122         {
 123             // Received an older checkpoint, trace back from current checkpoint
 124             // to the same height of the received checkpoint to verify
 125             // that current checkpoint should be a descendant block
 126             CBlockIndex* pindex = pindexSyncCheckpoint;
 127             while (pindex->nHeight > pindexCheckpointRecv->nHeight)
 128                 if (!(pindex = pindex->pprev))
 129                     return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
 130             if (pindex->GetBlockHash() != hashCheckpoint)
 131             {
 132                 hashInvalidCheckpoint = hashCheckpoint;
 133                 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 134             }
 135             return false; // ignore older checkpoint
 136         }
 137
 138         // Received checkpoint should be a descendant block of the current
 139         // checkpoint. Trace back to the same height of current checkpoint
 140         // to verify.
 141         CBlockIndex* pindex = pindexCheckpointRecv;
 142         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
 143             if (!(pindex = pindex->pprev))
 144                 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
 145         if (pindex->GetBlockHash() != hashSyncCheckpoint)
 146         {
 147             hashInvalidCheckpoint = hashCheckpoint;
 148             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 149         }
 150         return true;
 151     }
 152
 153     bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
 154     {
 155         CTxDB txdb;
 156         txdb.TxnBegin();
 157         if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
 158         {
 159             txdb.TxnAbort();
 160             return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 161         }
 162         if (!txdb.TxnCommit())
 163             return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 164         txdb.Close();
 165
 166         Checkpoints::hashSyncCheckpoint = hashCheckpoint;
 167         return true;
 168     }
 169
 170     bool AcceptPendingSyncCheckpoint()
 171     {
 172         LOCK(cs_hashSyncCheckpoint);
 173         if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 174         {
 175             if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 176             {
 177                 hashPendingCheckpoint = 0;
 178                 checkpointMessagePending.SetNull();
 179                 return false;
 180             }
 181
 182             CTxDB txdb;
 183             CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 184             if (!pindexCheckpoint->IsInMainChain())
 185             {
 186                 CBlock block;
 187                 if (!block.ReadFromDisk(pindexCheckpoint))
 188                     return error("AcceptPendingSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 189                 if (!block.SetBestChain(txdb, pindexCheckpoint))
 190                 {
 191                     hashInvalidCheckpoint = hashPendingCheckpoint;
 192                     return error("AcceptPendingSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 193                 }
 194             }
 195             txdb.Close();
 196
 197             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 198                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 199             hashPendingCheckpoint = 0;
 200             checkpointMessage = checkpointMessagePending;
 201             checkpointMessagePending.SetNull();
 202             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 203             // relay the checkpoint
 204             if (!checkpointMessage.IsNull())
 205             {
 206                 BOOST_FOREACH(CNode* pnode, vNodes)
 207                     checkpointMessage.RelayTo(pnode);
 208             }
 209             return true;
 210         }
 211         return false;
 212     }
 213
 214     // Automatically select a suitable sync-checkpoint
 215     uint256 AutoSelectSyncCheckpoint()
 216     {
 217         // Proof-of-work blocks are immediately checkpointed
 218         // to defend against 51% attack which rejects other miners block
 219
 220         // Select the last proof-of-work block
 221         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 222         // Search forward for a block within max span and maturity window
 223         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + std::min(6, nCoinbaseMaturity - 20) <= pindexBest->nHeight))
 224             pindex = pindex->pnext;
 225         return pindex->GetBlockHash();
 226     }
 227
 228     // Check against synchronized checkpoint
 229     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 230     {
 231         if (fTestNet) return true; // Testnet has no checkpoints
 232         int nHeight = pindexPrev->nHeight + 1;
 233
 234         LOCK(cs_hashSyncCheckpoint);
 235         // sync-checkpoint should always be accepted block
 236         assert(mapBlockIndex.count(hashSyncCheckpoint));
 237         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 238
 239         if (nHeight > pindexSync->nHeight)
 240         {
 241             // trace back to same height as sync-checkpoint
 242             const CBlockIndex* pindex = pindexPrev;
 243             while (pindex->nHeight > pindexSync->nHeight)
 244                 if (!(pindex = pindex->pprev))
 245                     return error("CheckSync: pprev null - block index structure failure");
 246             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 247                 return false; // only descendant of sync-checkpoint can pass check
 248         }
 249         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 250             return false; // same height with sync-checkpoint
 251         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 252             return false; // lower height than sync-checkpoint
 253         return true;
 254     }
 255
 256     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 257     {
 258         LOCK(cs_hashSyncCheckpoint);
 259         if (hashPendingCheckpoint == 0)
 260             return false;
 261         if (hashBlock == hashPendingCheckpoint)
 262             return true;
 263         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 264             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 265             return true;
 266         return false;
 267     }
 268
 269     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 270     bool ResetSyncCheckpoint()
 271     {
 272         LOCK(cs_hashSyncCheckpoint);
 273         const uint256& hash = mapCheckpoints.rbegin()->second.hashCheckPoint;
 274         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 275         {
 276             // checkpoint block accepted but not yet in main chain
 277             printf("ResetSyncCheckpoint: SetBestChain to hardened checkpoint %s\n", hash.ToString().c_str());
 278             CTxDB txdb;
 279             CBlock block;
 280             if (!block.ReadFromDisk(mapBlockIndex[hash]))
 281                 return error("ResetSyncCheckpoint: ReadFromDisk failed for hardened checkpoint %s", hash.ToString().c_str());
 282             if (!block.SetBestChain(txdb, mapBlockIndex[hash]))
 283             {
 284                 return error("ResetSyncCheckpoint: SetBestChain failed for hardened checkpoint %s", hash.ToString().c_str());
 285             }
 286             txdb.Close();
 287         }
 288         else if(!mapBlockIndex.count(hash))
 289         {
 290             // checkpoint block not yet accepted
 291             hashPendingCheckpoint = hash;
 292             checkpointMessagePending.SetNull();
 293             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 294         }
 295
 296         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 297         {
 298             const uint256& hash = i.second.hashCheckPoint;
 299             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 300             {
 301                 if (!WriteSyncCheckpoint(hash))
 302                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 303                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 304                 return true;
 305             }
 306         }
 307
 308         return false;
 309     }
 310
 311     void AskForPendingSyncCheckpoint(CNode* pfrom)
 312     {
 313         LOCK(cs_hashSyncCheckpoint);
 314         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 315             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 316     }
 317
 318     bool SetCheckpointPrivKey(std::string strPrivKey)
 319     {
 320         // Test signing a sync-checkpoint with genesis block
 321         CSyncCheckpoint checkpoint;
 322         checkpoint.hashCheckpoint = !fTestNet ? hashGenesisBlock : hashGenesisBlockTestNet;
 323         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 324         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 325         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 326
 327         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 328         CKey key;
 329         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 330         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 331             return false;
 332
 333         // Test signing successful, proceed
 334         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 335         return true;
 336     }
 337
 338     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 339     {
 340         CSyncCheckpoint checkpoint;
 341         checkpoint.hashCheckpoint = hashCheckpoint;
 342         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 343         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 344         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 345
 346         if (CSyncCheckpoint::strMasterPrivKey.empty())
 347             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 348         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 349         CKey key;
 350         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 351         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 352             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 353
 354         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 355         {
 356             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 357             return false;
 358         }
 359
 360         // Relay checkpoint
 361         {
 362             LOCK(cs_vNodes);
 363             BOOST_FOREACH(CNode* pnode, vNodes)
 364                 checkpoint.RelayTo(pnode);
 365         }
 366         return true;
 367     }
 368
 369     // Is the sync-checkpoint outside maturity window?
 370     bool IsMatureSyncCheckpoint()
 371     {
 372         LOCK(cs_hashSyncCheckpoint);
 373         // sync-checkpoint should always be accepted block
 374         assert(mapBlockIndex.count(hashSyncCheckpoint));
 375         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 376         return (nBestHeight >= pindexSync->nHeight + nCoinbaseMaturity ||
 377                 pindexSync->GetBlockTime() + nStakeMinAge < GetAdjustedTime());
 378     }
 379
 380     // Is the sync-checkpoint too old?
 381     bool IsSyncCheckpointTooOld(unsigned int nSeconds)
 382     {
 383         LOCK(cs_hashSyncCheckpoint);
 384         // sync-checkpoint should always be accepted block
 385         assert(mapBlockIndex.count(hashSyncCheckpoint));
 386         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 387         return (pindexSync->GetBlockTime() + nSeconds < GetAdjustedTime());
 388     }
 389 }
 390
 391 // ppcoin: sync-checkpoint master key
 392 const std::string CSyncCheckpoint::strMasterPubKey = "04a51b735f816de4ec3f891d5b38bbc91e1f7245c7c08d17990760b86b4d8fc3910a850ffecf73bfa8886f01739a0c4c4322201282d07b6e48ce931cc92af94850";
 393
 394 std::string CSyncCheckpoint::strMasterPrivKey = "";
 395
 396 // ppcoin: verify signature of sync-checkpoint message
 397 bool CSyncCheckpoint::CheckSignature()
 398 {
 399     CKey key;
 400     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 401         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 402     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 403         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 404
 405     // Now unserialize the data
 406     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 407     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 408     return true;
 409 }
 410
 411 // ppcoin: process synchronized checkpoint
 412 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 413 {
 414     if (!CheckSignature())
 415         return false;
 416
 417     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 418     if (!mapBlockIndex.count(hashCheckpoint))
 419     {
 420         // We haven't received the checkpoint chain, keep the checkpoint as pending
 421         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 422         Checkpoints::checkpointMessagePending = *this;
 423         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 424         // Ask this guy to fill in what we're missing
 425         if (pfrom)
 426         {
 427             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 428             // ask directly as well in case rejected earlier by duplicate
 429             // proof-of-stake because getblocks may not get it this time
 430             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 431         }
 432         return false;
 433     }
 434
 435     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 436         return false;
 437
 438     CTxDB txdb;
 439     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 440     if (!pindexCheckpoint->IsInMainChain())
 441     {
 442         // checkpoint chain received but not yet main chain
 443         CBlock block;
 444         if (!block.ReadFromDisk(pindexCheckpoint))
 445             return error("ProcessSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 446         if (!block.SetBestChain(txdb, pindexCheckpoint))
 447         {
 448             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 449             return error("ProcessSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 450         }
 451     }
 452     txdb.Close();
 453
 454     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 455         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 456     Checkpoints::checkpointMessage = *this;
 457     Checkpoints::hashPendingCheckpoint = 0;
 458     Checkpoints::checkpointMessagePending.SetNull();
 459     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 460     return true;
 461 }