src/checkpoints.cpp

   1 // Copyright (c) 2009-2012 The Bitcoin developers
   2 // Copyright (c) 2011-2012 The PPCoin developers
   3 // Distributed under the MIT/X11 software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #include <boost/assign/list_of.hpp> // for 'map_list_of()'
   7 #include <boost/foreach.hpp>
   8
   9 #include "checkpoints.h"
  10
  11 #include "db.h"
  12 #include "main.h"
  13 #include "uint256.h"
  14
  15 namespace Checkpoints
  16 {
  17     typedef std::map<int, uint256> MapCheckpoints;   // hardened checkpoints
  18
  19     //
  20     // What makes a good checkpoint block?
  21     // + Is surrounded by blocks with reasonable timestamps
  22     //   (no blocks before with a timestamp after, none after with
  23     //    timestamp before)
  24     // + Contains no strange transactions
  25     //
  26     static MapCheckpoints mapCheckpoints =
  27         boost::assign::map_list_of
  28         ( 0, hashGenesisBlockOfficial )
  29         ; // ppcoin: no checkpoint yet; to be created in future releases
  30
  31     bool CheckHardened(int nHeight, const uint256& hash)
  32     {
  33         if (fTestNet) return true; // Testnet has no checkpoints
  34
  35         MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
  36         if (i == mapCheckpoints.end()) return true;
  37         return hash == i->second;
  38     }
  39
  40     int GetTotalBlocksEstimate()
  41     {
  42         if (fTestNet) return 0;
  43
  44         return mapCheckpoints.rbegin()->first;
  45     }
  46
  47     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  48     {
  49         if (fTestNet) {
  50             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hashGenesisBlock);
  51             if (t != mapBlockIndex.end())
  52                 return t->second;
  53             return NULL;
  54         }
  55
  56         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
  57         {
  58             const uint256& hash = i.second;
  59             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  60             if (t != mapBlockIndex.end())
  61                 return t->second;
  62         }
  63         return NULL;
  64     }
  65
  66     // ppcoin: synchronized checkpoint (centrally broadcasted)
  67     uint256 hashSyncCheckpoint = 0;
  68     uint256 hashPendingCheckpoint = 0;
  69     CSyncCheckpoint checkpointMessage;
  70     CSyncCheckpoint checkpointMessagePending;
  71     uint256 hashInvalidCheckpoint = 0;
  72     CCriticalSection cs_hashSyncCheckpoint;
  73
  74     // ppcoin: get last synchronized checkpoint
  75     CBlockIndex* GetLastSyncCheckpoint()
  76     {
  77         LOCK(cs_hashSyncCheckpoint);
  78         if (!mapBlockIndex.count(hashSyncCheckpoint))
  79             error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  80         else
  81             return mapBlockIndex[hashSyncCheckpoint];
  82         return NULL;
  83     }
  84
  85     // ppcoin: only descendant of current sync-checkpoint is allowed
  86     bool ValidateSyncCheckpoint(uint256 hashCheckpoint)
  87     {
  88         if (!mapBlockIndex.count(hashSyncCheckpoint))
  89             return error("ValidateSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  90         if (!mapBlockIndex.count(hashCheckpoint))
  91             return error("ValidateSyncCheckpoint: block index missing for received sync-checkpoint %s", hashCheckpoint.ToString().c_str());
  92
  93         CBlockIndex* pindexSyncCheckpoint = mapBlockIndex[hashSyncCheckpoint];
  94         CBlockIndex* pindexCheckpointRecv = mapBlockIndex[hashCheckpoint];
  95
  96         if (pindexCheckpointRecv->nHeight <= pindexSyncCheckpoint->nHeight)
  97         {
  98             // Received an older checkpoint, trace back from current checkpoint
  99             // to the same height of the received checkpoint to verify
 100             // that current checkpoint should be a descendant block
 101             CBlockIndex* pindex = pindexSyncCheckpoint;
 102             while (pindex->nHeight > pindexCheckpointRecv->nHeight)
 103                 if (!(pindex = pindex->pprev))
 104                     return error("ValidateSyncCheckpoint: pprev1 null - block index structure failure");
 105             if (pindex->GetBlockHash() != hashCheckpoint)
 106             {
 107                 hashInvalidCheckpoint = hashCheckpoint;
 108                 return error("ValidateSyncCheckpoint: new sync-checkpoint %s is conflicting with current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 109             }
 110             return false; // ignore older checkpoint
 111         }
 112
 113         // Received checkpoint should be a descendant block of the current
 114         // checkpoint. Trace back to the same height of current checkpoint
 115         // to verify.
 116         CBlockIndex* pindex = pindexCheckpointRecv;
 117         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
 118             if (!(pindex = pindex->pprev))
 119                 return error("ValidateSyncCheckpoint: pprev2 null - block index structure failure");
 120         if (pindex->GetBlockHash() != hashSyncCheckpoint)
 121         {
 122             hashInvalidCheckpoint = hashCheckpoint;
 123             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
 124         }
 125         return true;
 126     }
 127
 128     bool WriteSyncCheckpoint(const uint256& hashCheckpoint)
 129     {
 130         CTxDB txdb;
 131         txdb.TxnBegin();
 132         if (!txdb.WriteSyncCheckpoint(hashCheckpoint))
 133         {
 134             txdb.TxnAbort();
 135             return error("WriteSyncCheckpoint(): failed to write to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 136         }
 137         if (!txdb.TxnCommit())
 138             return error("WriteSyncCheckpoint(): failed to commit to db sync checkpoint %s", hashCheckpoint.ToString().c_str());
 139         txdb.Close();
 140
 141         Checkpoints::hashSyncCheckpoint = hashCheckpoint;
 142         return true;
 143     }
 144
 145     bool AcceptPendingSyncCheckpoint()
 146     {
 147         LOCK(cs_hashSyncCheckpoint);
 148         if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 149         {
 150             if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 151             {
 152                 hashPendingCheckpoint = 0;
 153                 checkpointMessagePending.SetNull();
 154                 return false;
 155             }
 156
 157             CTxDB txdb;
 158             CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 159             if (!pindexCheckpoint->IsInMainChain())
 160             {
 161                 CBlock block;
 162                 if (!block.ReadFromDisk(pindexCheckpoint))
 163                     return error("AcceptPendingSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 164                 if (!block.SetBestChain(txdb, pindexCheckpoint))
 165                 {
 166                     hashInvalidCheckpoint = hashPendingCheckpoint;
 167                     return error("AcceptPendingSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 168                 }
 169             }
 170             txdb.Close();
 171
 172             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 173                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 174             hashPendingCheckpoint = 0;
 175             checkpointMessage = checkpointMessagePending;
 176             checkpointMessagePending.SetNull();
 177             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 178             // relay the checkpoint
 179             if (!checkpointMessage.IsNull())
 180             {
 181                 BOOST_FOREACH(CNode* pnode, vNodes)
 182                     checkpointMessage.RelayTo(pnode);
 183             }
 184             return true;
 185         }
 186         return false;
 187     }
 188
 189     // Automatically select a suitable sync-checkpoint
 190     uint256 AutoSelectSyncCheckpoint()
 191     {
 192         // Proof-of-work blocks are immediately checkpointed
 193         // to defend against 51% attack which rejects other miners block
 194
 195         // Select the last proof-of-work block
 196         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 197         // Search forward for a block within max span and maturity window
 198         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + COINBASE_MATURITY - 20 <= pindexBest->nHeight))
 199             pindex = pindex->pnext;
 200         return pindex->GetBlockHash();
 201     }
 202
 203     // Check against synchronized checkpoint
 204     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 205     {
 206         if (fTestNet) return true; // Testnet has no checkpoints
 207         int nHeight = pindexPrev->nHeight + 1;
 208
 209         LOCK(cs_hashSyncCheckpoint);
 210         // sync-checkpoint should always be accepted block
 211         assert(mapBlockIndex.count(hashSyncCheckpoint));
 212         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 213
 214         if (nHeight > pindexSync->nHeight)
 215         {
 216             // trace back to same height as sync-checkpoint
 217             const CBlockIndex* pindex = pindexPrev;
 218             while (pindex->nHeight > pindexSync->nHeight)
 219                 if (!(pindex = pindex->pprev))
 220                     return error("CheckSync: pprev null - block index structure failure");
 221             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 222                 return false; // only descendant of sync-checkpoint can pass check
 223         }
 224         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 225             return false; // same height with sync-checkpoint
 226         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 227             return false; // lower height than sync-checkpoint
 228         return true;
 229     }
 230
 231     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 232     {
 233         LOCK(cs_hashSyncCheckpoint);
 234         if (hashPendingCheckpoint == 0)
 235             return false;
 236         if (hashBlock == hashPendingCheckpoint)
 237             return true;
 238         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 239             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 240             return true;
 241         return false;
 242     }
 243
 244     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 245     bool ResetSyncCheckpoint()
 246     {
 247         LOCK(cs_hashSyncCheckpoint);
 248         const uint256& hash = mapCheckpoints.rbegin()->second;
 249         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 250         {
 251             // checkpoint block accepted but not yet in main chain
 252             printf("ResetSyncCheckpoint: SetBestChain to hardened checkpoint %s\n", hash.ToString().c_str());
 253             CTxDB txdb;
 254             CBlock block;
 255             if (!block.ReadFromDisk(mapBlockIndex[hash]))
 256                 return error("ResetSyncCheckpoint: ReadFromDisk failed for hardened checkpoint %s", hash.ToString().c_str());
 257             if (!block.SetBestChain(txdb, mapBlockIndex[hash]))
 258             {
 259                 return error("ResetSyncCheckpoint: SetBestChain failed for hardened checkpoint %s", hash.ToString().c_str());
 260             }
 261             txdb.Close();
 262         }
 263         else if(!mapBlockIndex.count(hash))
 264         {
 265             // checkpoint block not yet accepted
 266             hashPendingCheckpoint = hash;
 267             checkpointMessagePending.SetNull();
 268             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 269         }
 270
 271         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 272         {
 273             const uint256& hash = i.second;
 274             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 275             {
 276                 if (!WriteSyncCheckpoint(hash))
 277                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 278                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 279                 return true;
 280             }
 281         }
 282
 283         return false;
 284     }
 285
 286     void AskForPendingSyncCheckpoint(CNode* pfrom)
 287     {
 288         LOCK(cs_hashSyncCheckpoint);
 289         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 290             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 291     }
 292
 293     bool SetCheckpointPrivKey(std::string strPrivKey)
 294     {
 295         // Test signing a sync-checkpoint with genesis block
 296         CSyncCheckpoint checkpoint;
 297         checkpoint.hashCheckpoint = hashGenesisBlock;
 298         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 299         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 300         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 301
 302         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 303         CKey key;
 304         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 305         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 306             return false;
 307
 308         // Test signing successful, proceed
 309         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 310         return true;
 311     }
 312
 313     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 314     {
 315         CSyncCheckpoint checkpoint;
 316         checkpoint.hashCheckpoint = hashCheckpoint;
 317         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 318         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 319         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 320
 321         if (CSyncCheckpoint::strMasterPrivKey.empty())
 322             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 323         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 324         CKey key;
 325         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 326         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 327             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 328
 329         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 330         {
 331             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 332             return false;
 333         }
 334
 335         // Relay checkpoint
 336         {
 337             LOCK(cs_vNodes);
 338             BOOST_FOREACH(CNode* pnode, vNodes)
 339                 checkpoint.RelayTo(pnode);
 340         }
 341         return true;
 342     }
 343
 344     // Is the sync-checkpoint outside maturity window?
 345     bool IsMatureSyncCheckpoint()
 346     {
 347         LOCK(cs_hashSyncCheckpoint);
 348         // sync-checkpoint should always be accepted block
 349         assert(mapBlockIndex.count(hashSyncCheckpoint));
 350         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 351         return (nBestHeight >= pindexSync->nHeight + COINBASE_MATURITY ||
 352                 pindexSync->GetBlockTime() + STAKE_MIN_AGE < GetAdjustedTime());
 353     }
 354 }
 355
 356 // ppcoin: sync-checkpoint master key
 357 const std::string CSyncCheckpoint::strMasterPubKey = "04c0c707c28533fd5c9f79d2d3a2d80dff259ad8f915241cd14608fb9bc07c74830efe8438f2b272a866b4af5e0c2cc2a9909972aefbd976937e39f46bb38c277c";
 358
 359 std::string CSyncCheckpoint::strMasterPrivKey = "";
 360
 361 // ppcoin: verify signature of sync-checkpoint message
 362 bool CSyncCheckpoint::CheckSignature()
 363 {
 364     CKey key;
 365     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 366         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 367     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 368         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 369
 370     // Now unserialize the data
 371     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 372     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 373     return true;
 374 }
 375
 376 // ppcoin: process synchronized checkpoint
 377 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 378 {
 379     if (!CheckSignature())
 380         return false;
 381
 382     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 383     if (!mapBlockIndex.count(hashCheckpoint))
 384     {
 385         // We haven't received the checkpoint chain, keep the checkpoint as pending
 386         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 387         Checkpoints::checkpointMessagePending = *this;
 388         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 389         // Ask this guy to fill in what we're missing
 390         if (pfrom)
 391         {
 392             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 393             // ask directly as well in case rejected earlier by duplicate
 394             // proof-of-stake because getblocks may not get it this time
 395             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 396         }
 397         return false;
 398     }
 399
 400     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 401         return false;
 402
 403     CTxDB txdb;
 404     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 405     if (!pindexCheckpoint->IsInMainChain())
 406     {
 407         // checkpoint chain received but not yet main chain
 408         CBlock block;
 409         if (!block.ReadFromDisk(pindexCheckpoint))
 410             return error("ProcessSyncCheckpoint: ReadFromDisk failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 411         if (!block.SetBestChain(txdb, pindexCheckpoint))
 412         {
 413             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 414             return error("ProcessSyncCheckpoint: SetBestChain failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 415         }
 416     }
 417     txdb.Close();
 418
 419     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 420         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 421     Checkpoints::checkpointMessage = *this;
 422     Checkpoints::hashPendingCheckpoint = 0;
 423     Checkpoints::checkpointMessagePending.SetNull();
 424     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 425     return true;
 426 }