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