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, hashGenesisBlock )
  28         ( 6000, uint256("0x000000000945e3c9d8e15df834e802521eb79f9ceb4191a27bdfadad4b777f4a"))
  29         ( 9690, uint256("0x00000000026561450859c46868099e0df6068a538f038cb18988fd8d47dcdaf5"))
  30         ( 13560, uint256("0xa1591a0fcbf11f282d671581edb9f0aadcd06fee69761081e0a3245914c13729"))
  31         ( 14189, uint256("0x00000000020f76474d2522b19c7bfafc43ba6ecbabae54293bcd9546159c8c1d"))
  32         ( 19600, uint256("0x252ae08d6df4bc7220c1dcdaed7b8a6e78bab05a60173511e8f565a3a38ce3c3"))
  33         ( 21800, uint256("0x64bdeb35023f240ed01beaa082f840f2d4cc6defccbbcda1260de87e58296b37"))
  34         ( 26174, uint256("0x00000000006cf1bfaa0d73caea92f6d2afa465651a76415b8d53b0bb0e01a8be"))
  35         ( 27451, uint256("0xd65424c24041b9f2e531f8f275f1a3c8bb105f0b29005b0bd577ae1a73341080"))
  36
  37         ;
  38
  39     // TestNet has no checkpoints
  40     static MapCheckpoints mapCheckpointsTestnet =
  41         boost::assign::map_list_of
  42         ( 0, hashGenesisBlockTestNet )
  43         ;
  44
  45     bool CheckHardened(int nHeight, const uint256& hash)
  46     {
  47         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  48
  49         MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
  50         if (i == checkpoints.end()) return true;
  51         return hash == i->second;
  52     }
  53
  54     int GetTotalBlocksEstimate()
  55     {
  56         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  57
  58         return checkpoints.rbegin()->first;
  59     }
  60
  61     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  62     {
  63         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
  64
  65         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
  66         {
  67             const uint256& hash = i.second;
  68             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  69             if (t != mapBlockIndex.end())
  70                 return t->second;
  71         }
  72         return NULL;
  73     }
  74
  75     // ppcoin: synchronized checkpoint (centrally broadcasted)
  76     uint256 hashSyncCheckpoint = 0;
  77     uint256 hashPendingCheckpoint = 0;
  78     CSyncCheckpoint checkpointMessage;
  79     CSyncCheckpoint checkpointMessagePending;
  80     uint256 hashInvalidCheckpoint = 0;
  81     CCriticalSection cs_hashSyncCheckpoint;
  82
  83     // ppcoin: get last synchronized checkpoint
  84     CBlockIndex* GetLastSyncCheckpoint()
  85     {
  86         LOCK(cs_hashSyncCheckpoint);
  87         if (!mapBlockIndex.count(hashSyncCheckpoint))
  88             error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  89         else
  90             return mapBlockIndex[hashSyncCheckpoint];
  91         return NULL;
  92     }
  93
  94     // ppcoin: only descendant of current sync-checkpoint is allowed
  95     bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
  96     {
  97         if (!mapBlockIndex.count(hashSyncCheckpoint))
  98             return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  99         if (!mapBlockIndex.count(hashCheckpoint))
 100             return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
 101
 102         CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
 103         CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
 104
 105         if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
 106         {
 107             // Received an older checkpoint, trace back from current checkpoint
 108             // to the same height of the received checkpoint to verify
 109             // that current checkpoint should be a descendant block
 110             CBlockIndex* pindex = pindexSyncCheckpoint;
 111             while (pindex->nHeight > pindexCheckpointRecv->nHeight)
 112                 if (!(pindex = pindex->pprev))
 113                     return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
 114             if (pindex->GetBlockHash() != hashCheckpoint)
 115             {
 116                 hashInvalidCheckpoint = hashCheckpoint;
 117                 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 118             }
 119             return false; // ignore older checkpoint
 120         }
 121
 122         // Received checkpoint should be a descendant block of the current
 123         // checkpoint. Trace back to the same height of current checkpoint
 124         // to verify.
 125         CBlockIndex* pindex = pindexCheckpointRecv;
 126         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
 127             if (!(pindex = pindex->pprev))
 128                 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
 129         if (pindex->GetBlockHash() != hashSyncCheckpoint)
 130         {
 131             hashInvalidCheckpoint = hashCheckpoint;
 132             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 133         }
 134         return true;
 135     }
 136
 137     bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
 138     {
 139         CTxDB txdb;
 140         txdb.TxnBegin();
 141         if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
 142         {
 143             txdb.TxnAbort();
 144             return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 145         }
 146         if (!txdb.TxnCommit())
 147             return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 148         txdb.Close();
 149
 150         Checkpoints::hashSyncCheckpoint = hashCheckpoint;
 151         return true;
 152     }
 153
 154     bool AcceptPendingSyncCheckpoint()
 155     {
 156         LOCK(cs_hashSyncCheckpoint);
 157         if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 158         {
 159             if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 160             {
 161                 hashPendingCheckpoint = 0;
 162                 checkpointMessagePending.SetNull();
 163                 return false;
 164             }
 165
 166             CTxDB txdb;
 167             CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 168             if (!pindexCheckpoint->IsInMainChain())
 169             {
 170                 CBlock block;
 171                 if (!block.ReadFromDisk(pindexCheckpoint))
 172                     return error("AcceptPendingSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 173                 if (!block.SetBestChain(txdb, pindexCheckpoint))
 174                 {
 175                     hashInvalidCheckpoint = hashPendingCheckpoint;
 176                     return error("AcceptPendingSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 177                 }
 178             }
 179             txdb.Close();
 180
 181             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 182                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 183             hashPendingCheckpoint = 0;
 184             checkpointMessage = checkpointMessagePending;
 185             checkpointMessagePending.SetNull();
 186             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 187             // relay the checkpoint
 188             if (!checkpointMessage.IsNull())
 189             {
 190                 BOOST_FOREACH(CNode* pnode, vNodes)
 191                     checkpointMessage.RelayTo(pnode);
 192             }
 193             return true;
 194         }
 195         return false;
 196     }
 197
 198     // Automatically select a suitable sync-checkpoint
 199     uint256 AutoSelectSyncCheckpoint()
 200     {
 201         // Proof-of-work blocks are immediately checkpointed
 202         // to defend against 51% attack which rejects other miners block
 203
 204         // Select the last proof-of-work block
 205         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 206         // Search forward for a block within max span and maturity window
 207         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + std::min(6, nCoinbaseMaturity - 20) <= pindexBest->nHeight))
 208             pindex = pindex->pnext;
 209         return pindex->GetBlockHash();
 210     }
 211
 212     // Check against synchronized checkpoint
 213     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 214     {
 215         if (fTestNet) return true; // Testnet has no checkpoints
 216         int nHeight = pindexPrev->nHeight + 1;
 217
 218         LOCK(cs_hashSyncCheckpoint);
 219         // sync-checkpoint should always be accepted block
 220         assert(mapBlockIndex.count(hashSyncCheckpoint));
 221         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 222
 223         if (nHeight > pindexSync->nHeight)
 224         {
 225             // trace back to same height as sync-checkpoint
 226             const CBlockIndex* pindex = pindexPrev;
 227             while (pindex->nHeight > pindexSync->nHeight)
 228                 if (!(pindex = pindex->pprev))
 229                     return error("CheckSync: pprev null - block index structure failure");
 230             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 231                 return false; // only descendant of sync-checkpoint can pass check
 232         }
 233         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 234             return false; // same height with sync-checkpoint
 235         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 236             return false; // lower height than sync-checkpoint
 237         return true;
 238     }
 239
 240     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 241     {
 242         LOCK(cs_hashSyncCheckpoint);
 243         if (hashPendingCheckpoint == 0)
 244             return false;
 245         if (hashBlock == hashPendingCheckpoint)
 246             return true;
 247         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 248             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 249             return true;
 250         return false;
 251     }
 252
 253     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 254     bool ResetSyncCheckpoint()
 255     {
 256         LOCK(cs_hashSyncCheckpoint);
 257         const uint256& hash = mapCheckpoints.rbegin()->second;
 258         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 259         {
 260             // checkpoint block accepted but not yet in main chain
 261             printf("ResetSyncCheckpoint: SetBestChain to hardened checkpoint %s\n", hash.ToString().c_str());
 262             CTxDB txdb;
 263             CBlock block;
 264             if (!block.ReadFromDisk(mapBlockIndex[hash]))
 265                 return error("ResetSyncCheckpoint: ReadFromDisk failed for hardened checkpoint %s", hash.ToString().c_str());
 266             if (!block.SetBestChain(txdb, mapBlockIndex[hash]))
 267             {
 268                 return error("ResetSyncCheckpoint: SetBestChain failed for hardened checkpoint %s", hash.ToString().c_str());
 269             }
 270             txdb.Close();
 271         }
 272         else if(!mapBlockIndex.count(hash))
 273         {
 274             // checkpoint block not yet accepted
 275             hashPendingCheckpoint = hash;
 276             checkpointMessagePending.SetNull();
 277             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 278         }
 279
 280         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 281         {
 282             const uint256& hash = i.second;
 283             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 284             {
 285                 if (!WriteSyncCheckpoint(hash))
 286                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 287                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 288                 return true;
 289             }
 290         }
 291
 292         return false;
 293     }
 294
 295     void AskForPendingSyncCheckpoint(CNode* pfrom)
 296     {
 297         LOCK(cs_hashSyncCheckpoint);
 298         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 299             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 300     }
 301
 302     bool SetCheckpointPrivKey(std::string strPrivKey)
 303     {
 304         // Test signing a sync-checkpoint with genesis block
 305         CSyncCheckpoint checkpoint;
 306         checkpoint.hashCheckpoint = !fTestNet ? hashGenesisBlock : hashGenesisBlockTestNet;
 307         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 308         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 309         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 310
 311         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 312         CKey key;
 313         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 314         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 315             return false;
 316
 317         // Test signing successful, proceed
 318         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 319         return true;
 320     }
 321
 322     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 323     {
 324         CSyncCheckpoint checkpoint;
 325         checkpoint.hashCheckpoint = hashCheckpoint;
 326         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 327         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 328         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 329
 330         if (CSyncCheckpoint::strMasterPrivKey.empty())
 331             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 332         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 333         CKey key;
 334         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 335         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 336             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 337
 338         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 339         {
 340             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 341             return false;
 342         }
 343
 344         // Relay checkpoint
 345         {
 346             LOCK(cs_vNodes);
 347             BOOST_FOREACH(CNode* pnode, vNodes)
 348                 checkpoint.RelayTo(pnode);
 349         }
 350         return true;
 351     }
 352
 353     // Is the sync-checkpoint outside maturity window?
 354     bool IsMatureSyncCheckpoint()
 355     {
 356         LOCK(cs_hashSyncCheckpoint);
 357         // sync-checkpoint should always be accepted block
 358         assert(mapBlockIndex.count(hashSyncCheckpoint));
 359         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 360         return (nBestHeight >= pindexSync->nHeight + nCoinbaseMaturity ||
 361                 pindexSync->GetBlockTime() + nStakeMinAge < GetAdjustedTime());
 362     }
 363
 364     // Is the sync-checkpoint too old?
 365     bool IsSyncCheckpointTooOld(unsigned int nSeconds)
 366     {
 367         LOCK(cs_hashSyncCheckpoint);
 368         // sync-checkpoint should always be accepted block
 369         assert(mapBlockIndex.count(hashSyncCheckpoint));
 370         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 371         return (pindexSync->GetBlockTime() + nSeconds < GetAdjustedTime());
 372     }
 373 }
 374
 375 // ppcoin: sync-checkpoint master key
 376 const std::string CSyncCheckpoint::strMasterPubKey = "04a51b735f816de4ec3f891d5b38bbc91e1f7245c7c08d17990760b86b4d8fc3910a850ffecf73bfa8886f01739a0c4c4322201282d07b6e48ce931cc92af94850";
 377
 378 std::string CSyncCheckpoint::strMasterPrivKey = "";
 379
 380 // ppcoin: verify signature of sync-checkpoint message
 381 bool CSyncCheckpoint::CheckSignature()
 382 {
 383     CKey key;
 384     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 385         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 386     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 387         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 388
 389     // Now unserialize the data
 390     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 391     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 392     return true;
 393 }
 394
 395 // ppcoin: process synchronized checkpoint
 396 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 397 {
 398     if (!CheckSignature())
 399         return false;
 400
 401     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 402     if (!mapBlockIndex.count(hashCheckpoint))
 403     {
 404         // We haven't received the checkpoint chain, keep the checkpoint as pending
 405         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 406         Checkpoints::checkpointMessagePending = *this;
 407         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 408         // Ask this guy to fill in what we're missing
 409         if (pfrom)
 410         {
 411             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 412             // ask directly as well in case rejected earlier by duplicate
 413             // proof-of-stake because getblocks may not get it this time
 414             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 415         }
 416         return false;
 417     }
 418
 419     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 420         return false;
 421
 422     CTxDB txdb;
 423     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 424     if (!pindexCheckpoint->IsInMainChain())
 425     {
 426         // checkpoint chain received but not yet main chain
 427         CBlock block;
 428         if (!block.ReadFromDisk(pindexCheckpoint))
 429             return error("ProcessSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 430         if (!block.SetBestChain(txdb, pindexCheckpoint))
 431         {
 432             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 433             return error("ProcessSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 434         }
 435     }
 436     txdb.Close();
 437
 438     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 439         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 440     Checkpoints::checkpointMessage = *this;
 441     Checkpoints::hashPendingCheckpoint = 0;
 442     Checkpoints::checkpointMessagePending.SetNull();
 443     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 444     return true;
 445 }