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                 txdb.TxnBegin();
 162                 if (!Reorganize(txdb, pindexCheckpoint))
 163                 {
 164                     txdb.TxnAbort();
 165                     hashInvalidCheckpoint = hashPendingCheckpoint;
 166                     return error("AcceptPendingSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 167                 }
 168             }
 169             txdb.Close();
 170
 171             if (!WriteSyncCheckpoint(hashPendingCheckpoint))
 172                 return error("AcceptPendingSyncCheckpoint(): failed to write sync checkpoint %s", hashPendingCheckpoint.ToString().c_str());
 173             hashPendingCheckpoint = 0;
 174             checkpointMessage = checkpointMessagePending;
 175             checkpointMessagePending.SetNull();
 176             printf("AcceptPendingSyncCheckpoint : sync-checkpoint at %s\n", hashSyncCheckpoint.ToString().c_str());
 177             // relay the checkpoint
 178             if (!checkpointMessage.IsNull())
 179             {
 180                 BOOST_FOREACH(CNode* pnode, vNodes)
 181                     checkpointMessage.RelayTo(pnode);
 182             }
 183             return true;
 184         }
 185         return false;
 186     }
 187
 188     // Automatically select a suitable sync-checkpoint
 189     uint256 AutoSelectSyncCheckpoint()
 190     {
 191         // Proof-of-work blocks are immediately checkpointed
 192         // to defend against 51% attack which rejects other miners block
 193
 194         // Select the last proof-of-work block
 195         const CBlockIndex *pindex = GetLastBlockIndex(pindexBest, false);
 196         // Search forward for a block within max span and maturity window
 197         while (pindex->pnext && (pindex->GetBlockTime() + CHECKPOINT_MAX_SPAN <= pindexBest->GetBlockTime() || pindex->nHeight + COINBASE_MATURITY - 20 <= pindexBest->nHeight))
 198             pindex = pindex->pnext;
 199         return pindex->GetBlockHash();
 200     }
 201
 202     // Check against synchronized checkpoint
 203     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 204     {
 205         if (fTestNet) return true; // Testnet has no checkpoints
 206         int nHeight = pindexPrev->nHeight + 1;
 207
 208         LOCK(cs_hashSyncCheckpoint);
 209         // sync-checkpoint should always be accepted block
 210         assert(mapBlockIndex.count(hashSyncCheckpoint));
 211         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 212
 213         if (nHeight > pindexSync->nHeight)
 214         {
 215             // trace back to same height as sync-checkpoint
 216             const CBlockIndex* pindex = pindexPrev;
 217             while (pindex->nHeight > pindexSync->nHeight)
 218                 if (!(pindex = pindex->pprev))
 219                     return error("CheckSync: pprev null - block index structure failure");
 220             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 221                 return false; // only descendant of sync-checkpoint can pass check
 222         }
 223         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 224             return false; // same height with sync-checkpoint
 225         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 226             return false; // lower height than sync-checkpoint
 227         return true;
 228     }
 229
 230     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 231     {
 232         LOCK(cs_hashSyncCheckpoint);
 233         if (hashPendingCheckpoint == 0)
 234             return false;
 235         if (hashBlock == hashPendingCheckpoint)
 236             return true;
 237         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 238             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 239             return true;
 240         return false;
 241     }
 242
 243     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 244     bool ResetSyncCheckpoint()
 245     {
 246         LOCK(cs_hashSyncCheckpoint);
 247         const uint256& hash = mapCheckpoints.rbegin()->second;
 248         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 249         {
 250             // checkpoint block accepted but not yet in main chain
 251             printf("ResetSyncCheckpoint: Reorganize to hardened checkpoint %s\n", hash.ToString().c_str());
 252             CTxDB txdb;
 253             txdb.TxnBegin();
 254             if (!Reorganize(txdb, mapBlockIndex[hash]))
 255             {
 256                 txdb.TxnAbort();
 257                 return error("ResetSyncCheckpoint: Reorganize failed for hardened checkpoint %s", hash.ToString().c_str());
 258             }
 259             txdb.Close();
 260         }
 261         else if(!mapBlockIndex.count(hash))
 262         {
 263             // checkpoint block not yet accepted
 264             hashPendingCheckpoint = hash;
 265             checkpointMessagePending.SetNull();
 266             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 267         }
 268
 269         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 270         {
 271             const uint256& hash = i.second;
 272             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 273             {
 274                 if (!WriteSyncCheckpoint(hash))
 275                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 276                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 277                 return true;
 278             }
 279         }
 280
 281         return false;
 282     }
 283
 284     void AskForPendingSyncCheckpoint(CNode* pfrom)
 285     {
 286         LOCK(cs_hashSyncCheckpoint);
 287         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 288             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 289     }
 290
 291     bool SetCheckpointPrivKey(std::string strPrivKey)
 292     {
 293         // Test signing a sync-checkpoint with genesis block
 294         CSyncCheckpoint checkpoint;
 295         checkpoint.hashCheckpoint = hashGenesisBlock;
 296         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 297         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 298         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 299
 300         std::vector<unsigned char> vchPrivKey = ParseHex(strPrivKey);
 301         CKey key;
 302         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 303         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 304             return false;
 305
 306         // Test signing successful, proceed
 307         CSyncCheckpoint::strMasterPrivKey = strPrivKey;
 308         return true;
 309     }
 310
 311     bool SendSyncCheckpoint(uint256 hashCheckpoint)
 312     {
 313         CSyncCheckpoint checkpoint;
 314         checkpoint.hashCheckpoint = hashCheckpoint;
 315         CDataStream sMsg(SER_NETWORK, PROTOCOL_VERSION);
 316         sMsg << (CUnsignedSyncCheckpoint)checkpoint;
 317         checkpoint.vchMsg = std::vector<unsigned char>(sMsg.begin(), sMsg.end());
 318
 319         if (CSyncCheckpoint::strMasterPrivKey.empty())
 320             return error("SendSyncCheckpoint: Checkpoint master key unavailable.");
 321         std::vector<unsigned char> vchPrivKey = ParseHex(CSyncCheckpoint::strMasterPrivKey);
 322         CKey key;
 323         key.SetPrivKey(CPrivKey(vchPrivKey.begin(), vchPrivKey.end())); // if key is not correct openssl may crash
 324         if (!key.Sign(Hash(checkpoint.vchMsg.begin(), checkpoint.vchMsg.end()), checkpoint.vchSig))
 325             return error("SendSyncCheckpoint: Unable to sign checkpoint, check private key?");
 326
 327         if(!checkpoint.ProcessSyncCheckpoint(NULL))
 328         {
 329             printf("WARNING: SendSyncCheckpoint: Failed to process checkpoint.\n");
 330             return false;
 331         }
 332
 333         // Relay checkpoint
 334         {
 335             LOCK(cs_vNodes);
 336             BOOST_FOREACH(CNode* pnode, vNodes)
 337                 checkpoint.RelayTo(pnode);
 338         }
 339         return true;
 340     }
 341
 342     // Is the sync-checkpoint outside maturity window?
 343     bool IsMatureSyncCheckpoint()
 344     {
 345         LOCK(cs_hashSyncCheckpoint);
 346         // sync-checkpoint should always be accepted block
 347         assert(mapBlockIndex.count(hashSyncCheckpoint));
 348         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 349         return (nBestHeight >= pindexSync->nHeight + COINBASE_MATURITY);
 350     }
 351 }
 352
 353 // ppcoin: sync-checkpoint master key
 354 const std::string CSyncCheckpoint::strMasterPubKey = "0424f20205e5da98ba632bbd278a11a6499585f62bfb2c782377ef59f0251daab8085fc31471bcb8180bc75ed0fa41bb50c7c084511d54015a3a5241d645c7268a";
 355
 356 std::string CSyncCheckpoint::strMasterPrivKey = "";
 357
 358 // ppcoin: verify signature of sync-checkpoint message
 359 bool CSyncCheckpoint::CheckSignature()
 360 {
 361     CKey key;
 362     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 363         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 364     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 365         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 366
 367     // Now unserialize the data
 368     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 369     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 370     return true;
 371 }
 372
 373 // ppcoin: process synchronized checkpoint
 374 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 375 {
 376     if (!CheckSignature())
 377         return false;
 378
 379     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 380     if (!mapBlockIndex.count(hashCheckpoint))
 381     {
 382         // We haven't received the checkpoint chain, keep the checkpoint as pending
 383         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 384         Checkpoints::checkpointMessagePending = *this;
 385         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 386         // Ask this guy to fill in what we're missing
 387         if (pfrom)
 388         {
 389             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 390             // ask directly as well in case rejected earlier by duplicate
 391             // proof-of-stake because getblocks may not get it this time
 392             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 393         }
 394         return false;
 395     }
 396
 397     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 398         return false;
 399
 400     CTxDB txdb;
 401     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 402     if (!pindexCheckpoint->IsInMainChain())
 403     {
 404         // checkpoint chain received but not yet main chain
 405         txdb.TxnBegin();
 406         if (!Reorganize(txdb, pindexCheckpoint))
 407         {
 408             txdb.TxnAbort();
 409             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 410             return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 411         }
 412     }
 413     txdb.Close();
 414
 415     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 416         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 417     Checkpoints::checkpointMessage = *this;
 418     Checkpoints::hashPendingCheckpoint = 0;
 419     Checkpoints::checkpointMessagePending.SetNull();
 420     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 421     return true;
 422 }