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("ProcessSyncCheckpoint: 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     uint256 AutoSelectSyncCheckpoint()
 189     {
 190         // select a block some time ago
 191         CBlockIndex *pindex = mapBlockIndex[hashSyncCheckpoint];
 192         while (pindex->pnext && pindex->pnext->GetBlockTime() + CHECKPOINT_MIN_SPAN <= GetAdjustedTime())
 193             pindex = pindex->pnext;
 194         return pindex->GetBlockHash();
 195     }
 196
 197     // Check against synchronized checkpoint
 198     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 199     {
 200         if (fTestNet) return true; // Testnet has no checkpoints
 201         int nHeight = pindexPrev->nHeight + 1;
 202
 203         LOCK(cs_hashSyncCheckpoint);
 204         // sync-checkpoint should always be accepted block
 205         assert(mapBlockIndex.count(hashSyncCheckpoint));
 206         const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 207
 208         if (nHeight > pindexSync->nHeight)
 209         {
 210             // trace back to same height as sync-checkpoint
 211             const CBlockIndex* pindex = pindexPrev;
 212             while (pindex->nHeight > pindexSync->nHeight)
 213                 if (!(pindex = pindex->pprev))
 214                     return error("CheckSync: pprev null - block index structure failure");
 215             if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 216                 return false; // only descendant of sync-checkpoint can pass check
 217         }
 218         if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 219             return false; // same height with sync-checkpoint
 220         if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 221             return false; // lower height than sync-checkpoint
 222         return true;
 223     }
 224
 225     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 226     {
 227         LOCK(cs_hashSyncCheckpoint);
 228         if (hashPendingCheckpoint == 0)
 229             return false;
 230         if (hashBlock == hashPendingCheckpoint)
 231             return true;
 232         if (mapOrphanBlocks.count(hashPendingCheckpoint)
 233             && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 234             return true;
 235         return false;
 236     }
 237
 238     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 239     bool ResetSyncCheckpoint()
 240     {
 241         LOCK(cs_hashSyncCheckpoint);
 242         const uint256& hash = mapCheckpoints.rbegin()->second;
 243         if (mapBlockIndex.count(hash) && !mapBlockIndex[hash]->IsInMainChain())
 244         {
 245             // checkpoint block accepted but not yet in main chain
 246             printf("ResetSyncCheckpoint: Reorganize to hardened checkpoint %s\n", hash.ToString().c_str());
 247             CTxDB txdb;
 248             txdb.TxnBegin();
 249             if (!Reorganize(txdb, mapBlockIndex[hash]))
 250             {
 251                 txdb.TxnAbort();
 252                 return error("ResetSyncCheckpoint: Reorganize failed for hardened checkpoint %s", hash.ToString().c_str());
 253             }
 254             txdb.Close();
 255         }
 256         else if(!mapBlockIndex.count(hash))
 257         {
 258             // checkpoint block not yet accepted
 259             hashPendingCheckpoint = hash;
 260             checkpointMessagePending.SetNull();
 261             printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 262         }
 263
 264         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
 265         {
 266             const uint256& hash = i.second;
 267             if (mapBlockIndex.count(hash) && mapBlockIndex[hash]->IsInMainChain())
 268             {
 269                 if (!WriteSyncCheckpoint(hash))
 270                     return error("ResetSyncCheckpoint: failed to write sync checkpoint %s", hash.ToString().c_str());
 271                 printf("ResetSyncCheckpoint: sync-checkpoint reset to %s\n", hashSyncCheckpoint.ToString().c_str());
 272                 return true;
 273             }
 274         }
 275
 276         return false;
 277     }
 278
 279     void AskForPendingSyncCheckpoint(CNode* pfrom)
 280     {
 281         LOCK(cs_hashSyncCheckpoint);
 282         if (pfrom && hashPendingCheckpoint != 0 && (!mapBlockIndex.count(hashPendingCheckpoint)) && (!mapOrphanBlocks.count(hashPendingCheckpoint)))
 283             pfrom->AskFor(CInv(MSG_BLOCK, hashPendingCheckpoint));
 284     }
 285 }
 286
 287 // ppcoin: sync-checkpoint master key
 288 const std::string CSyncCheckpoint::strMasterPubKey = "0424f20205e5da98ba632bbd278a11a6499585f62bfb2c782377ef59f0251daab8085fc31471bcb8180bc75ed0fa41bb50c7c084511d54015a3a5241d645c7268a";
 289
 290 // ppcoin: verify signature of sync-checkpoint message
 291 bool CSyncCheckpoint::CheckSignature()
 292 {
 293     CKey key;
 294     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 295         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 296     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 297         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 298
 299     // Now unserialize the data
 300     CDataStream sMsg(vchMsg, SER_NETWORK, PROTOCOL_VERSION);
 301     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 302     return true;
 303 }
 304
 305 // ppcoin: process synchronized checkpoint
 306 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 307 {
 308     if (!CheckSignature())
 309         return false;
 310
 311     LOCK(Checkpoints::cs_hashSyncCheckpoint);
 312     if (!mapBlockIndex.count(hashCheckpoint))
 313     {
 314         // We haven't received the checkpoint chain, keep the checkpoint as pending
 315         Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 316         Checkpoints::checkpointMessagePending = *this;
 317         printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 318         // Ask this guy to fill in what we're missing
 319         if (pfrom)
 320         {
 321             pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 322             // ask directly as well in case rejected earlier by duplicate
 323             // proof-of-stake because getblocks may not get it this time
 324             pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 325         }
 326         return false;
 327     }
 328
 329     if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 330         return false;
 331
 332     CTxDB txdb;
 333     CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 334     if (!pindexCheckpoint->IsInMainChain())
 335     {
 336         // checkpoint chain received but not yet main chain
 337         txdb.TxnBegin();
 338         if (!Reorganize(txdb, pindexCheckpoint))
 339         {
 340             txdb.TxnAbort();
 341             Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 342             return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 343         }
 344     }
 345     txdb.Close();
 346
 347     if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 348         return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 349     Checkpoints::checkpointMessage = *this;
 350     Checkpoints::hashPendingCheckpoint = 0;
 351     Checkpoints::checkpointMessagePending.SetNull();
 352     printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 353     return true;
 354 }