src/checkpoints.cpp

   1 // Copyright (c) 2011 The Bitcoin developers
   2 // Copyright (c) 2011-2012 The PPCoin developers
   3 // Distributed under the MIT/X11 software license, see the accompanying
   4 // file license.txt 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 "headers.h"
  10 #include "checkpoints.h"
  11
  12 namespace Checkpoints
  13 {
  14     typedef std::map<int, uint256> MapCheckpoints;   // hardened checkpoints
  15
  16     //
  17     // What makes a good checkpoint block?
  18     // + Is surrounded by blocks with reasonable timestamps
  19     //   (no blocks before with a timestamp after, none after with
  20     //    timestamp before)
  21     // + Contains no strange transactions
  22     //
  23     static MapCheckpoints mapCheckpoints =
  24         boost::assign::map_list_of
  25         ( 0, hashGenesisBlockOfficial )
  26         ; // ppcoin: no checkpoint yet; to be created in future releases
  27
  28     bool CheckHardened(int nHeight, const uint256& hash)
  29     {
  30         if (fTestNet) return true; // Testnet has no checkpoints
  31
  32         MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
  33         if (i == mapCheckpoints.end()) return true;
  34         return hash == i->second;
  35     }
  36
  37     int GetTotalBlocksEstimate()
  38     {
  39         if (fTestNet) return 0;
  40
  41         return mapCheckpoints.rbegin()->first;
  42     }
  43
  44     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
  45     {
  46         if (fTestNet) {
  47             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hashGenesisBlock);
  48             if (t != mapBlockIndex.end())
  49                 return t->second;
  50             return NULL;
  51         }
  52
  53         int64 nResult;
  54         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
  55         {
  56             const uint256& hash = i.second;
  57             std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
  58             if (t != mapBlockIndex.end())
  59                 return t->second;
  60         }
  61         return NULL;
  62     }
  63
  64     // ppcoin: synchronized checkpoint (centrally broadcasted)
  65     uint256 hashSyncCheckpoint = 0;
  66     uint256 hashPendingCheckpoint = 0;
  67     CSyncCheckpoint checkpointMessage;
  68     CSyncCheckpoint checkpointMessagePending;
  69     uint256 hashInvalidCheckpoint = 0;
  70     CCriticalSection cs_hashSyncCheckpoint;
  71
  72     // ppcoin: get last synchronized checkpoint
  73     CBlockIndex* GetLastSyncCheckpoint()
  74     {
  75         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
  76         {
  77             if (!mapBlockIndex.count(hashSyncCheckpoint))
  78                 error("GetSyncCheckpoint: block index missing for current sync-checkpoint %s", hashSyncCheckpoint.ToString().c_str());
  79             else
  80                 return mapBlockIndex[hashSyncCheckpoint];
  81         }
  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         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
 148         {
 149             if (hashPendingCheckpoint != 0 && mapBlockIndex.count(hashPendingCheckpoint))
 150             {
 151                 if (!ValidateSyncCheckpoint(hashPendingCheckpoint))
 152                 {
 153                     hashPendingCheckpoint = 0;
 154                     checkpointMessagePending.SetNull();
 155                     return false;
 156                 }
 157
 158                 CTxDB txdb;
 159                 CBlockIndex* pindexCheckpoint = mapBlockIndex[hashPendingCheckpoint];
 160                 if (!pindexCheckpoint->IsInMainChain())
 161                 {
 162                     txdb.TxnBegin();
 163                     if (!Reorganize(txdb, pindexCheckpoint))
 164                     {
 165                         txdb.TxnAbort();
 166                         hashInvalidCheckpoint = hashPendingCheckpoint;
 167                         return error("ProcessSyncCheckpoint: Reorganize 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                     BOOST_FOREACH(CNode* pnode, vNodes)
 181                         checkpointMessage.RelayTo(pnode);
 182                 return true;
 183             }
 184         }
 185
 186         return false;
 187     }
 188
 189     uint256 AutoSelectSyncCheckpoint()
 190     {
 191         // select block roughly 8 hours ago
 192         CBlockIndex *pindex = mapBlockIndex[hashSyncCheckpoint];
 193         while (pindex->pnext && pindex->pnext->GetBlockTime() + AUTO_CHECKPOINT_MIN_SPAN <= GetAdjustedTime())
 194             pindex = pindex->pnext;
 195         return pindex->GetBlockHash();
 196     }
 197
 198     // Check against synchronized checkpoint
 199     bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
 200     {
 201         if (fTestNet) return true; // Testnet has no checkpoints
 202         int nHeight = pindexPrev->nHeight + 1;
 203
 204         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
 205         {
 206             // sync-checkpoint should always be accepted block
 207             assert(mapBlockIndex.count(hashSyncCheckpoint));
 208             const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
 209
 210             if (nHeight > pindexSync->nHeight)
 211             {
 212                 // trace back to same height as sync-checkpoint
 213                 const CBlockIndex* pindex = pindexPrev;
 214                 while (pindex->nHeight > pindexSync->nHeight)
 215                     if (!(pindex = pindex->pprev))
 216                         return error("CheckSync: pprev null - block index structure failure");
 217                 if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
 218                     return false; // only descendant of sync-checkpoint can pass check
 219             }
 220             if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
 221                 return false; // same height with sync-checkpoint
 222             if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
 223                 return false; // lower height than sync-checkpoint
 224         }
 225         return true;
 226     }
 227
 228     bool WantedByPendingSyncCheckpoint(uint256 hashBlock)
 229     {
 230         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
 231         {
 232             if (hashPendingCheckpoint == 0)
 233                 return false;
 234             if (hashBlock == hashPendingCheckpoint)
 235                 return true;
 236             if (mapOrphanBlocks.count(hashPendingCheckpoint)
 237                 && hashBlock == WantedByOrphan(mapOrphanBlocks[hashPendingCheckpoint]))
 238                 return true;
 239         }
 240         return false;
 241     }
 242
 243     // ppcoin: reset synchronized checkpoint to last hardened checkpoint
 244     bool ResetSyncCheckpoint()
 245     {
 246         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
 247         {
 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: Reorganize to hardened checkpoint %s\n", hash.ToString().c_str());
 253                 CTxDB txdb;
 254                 txdb.TxnBegin();
 255                 if (!Reorganize(txdb, mapBlockIndex[hash]))
 256                 {
 257                     txdb.TxnAbort();
 258                     return error("ResetSyncCheckpoint: Reorganize failed for hardened checkpoint %s", hash.ToString().c_str());
 259                 }
 260                 txdb.Close();
 261             }
 262             else if(!mapBlockIndex.count(hash))
 263             {
 264                 // checkpoint block not yet accepted
 265                 hashPendingCheckpoint = hash;
 266                 checkpointMessagePending.SetNull();
 267                 printf("ResetSyncCheckpoint: pending for sync-checkpoint %s\n", hashPendingCheckpoint.ToString().c_str());
 268                 // TODO: when to ask for the checkpoint chain?
 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 }
 287
 288 // ppcoin: sync-checkpoint master key
 289 const std::string CSyncCheckpoint::strMasterPubKey = "0424f20205e5da98ba632bbd278a11a6499585f62bfb2c782377ef59f0251daab8085fc31471bcb8180bc75ed0fa41bb50c7c084511d54015a3a5241d645c7268a";
 290
 291 // ppcoin: verify signature of sync-checkpoint message
 292 bool CSyncCheckpoint::CheckSignature()
 293 {
 294     CKey key;
 295     if (!key.SetPubKey(ParseHex(CSyncCheckpoint::strMasterPubKey)))
 296         return error("CSyncCheckpoint::CheckSignature() : SetPubKey failed");
 297     if (!key.Verify(Hash(vchMsg.begin(), vchMsg.end()), vchSig))
 298         return error("CSyncCheckpoint::CheckSignature() : verify signature failed");
 299
 300     // Now unserialize the data
 301     CDataStream sMsg(vchMsg);
 302     sMsg >> *(CUnsignedSyncCheckpoint*)this;
 303     return true;
 304 }
 305
 306 // ppcoin: process synchronized checkpoint
 307 bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
 308 {
 309     if (!CheckSignature())
 310         return false;
 311
 312     CRITICAL_BLOCK(Checkpoints::cs_hashSyncCheckpoint)
 313     {
 314         if (!mapBlockIndex.count(hashCheckpoint))
 315         {
 316             // We haven't received the checkpoint chain, keep the checkpoint as pending
 317             Checkpoints::hashPendingCheckpoint = hashCheckpoint;
 318             Checkpoints::checkpointMessagePending = *this;
 319             printf("ProcessSyncCheckpoint: pending for sync-checkpoint %s\n", hashCheckpoint.ToString().c_str());
 320             // Ask this guy to fill in what we're missing
 321             if (pfrom)
 322             {
 323                 pfrom->PushGetBlocks(pindexBest, hashCheckpoint);
 324                 // ask directly as well in case rejected earlier by duplicate
 325                 // proof-of-stake because getblocks may not get it this time
 326                 pfrom->AskFor(CInv(MSG_BLOCK, mapOrphanBlocks.count(hashCheckpoint)? WantedByOrphan(mapOrphanBlocks[hashCheckpoint]) : hashCheckpoint));
 327             }
 328             return false;
 329         }
 330
 331         if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
 332             return false;
 333
 334         CTxDB txdb;
 335         CBlockIndex* pindexCheckpoint = mapBlockIndex[hashCheckpoint];
 336         if (!pindexCheckpoint->IsInMainChain())
 337         {
 338             // checkpoint chain received but not yet main chain
 339             txdb.TxnBegin();
 340             if (!Reorganize(txdb, pindexCheckpoint))
 341             {
 342                 txdb.TxnAbort();
 343                 Checkpoints::hashInvalidCheckpoint = hashCheckpoint;
 344                 return error("ProcessSyncCheckpoint: Reorganize failed for sync checkpoint %s", hashCheckpoint.ToString().c_str());
 345             }
 346         }
 347         txdb.Close();
 348
 349         if (!Checkpoints::WriteSyncCheckpoint(hashCheckpoint))
 350             return error("ProcessSyncCheckpoint(): failed to write sync checkpoint %s", hashCheckpoint.ToString().c_str());
 351         Checkpoints::checkpointMessage = *this;
 352         Checkpoints::hashPendingCheckpoint = 0;
 353         Checkpoints::checkpointMessagePending.SetNull();
 354         printf("ProcessSyncCheckpoint: sync-checkpoint at %s\n", hashCheckpoint.ToString().c_str());
 355     }
 356     return true;
 357 }