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