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