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