text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2015 The Bitcoin Core developers
  // Copyright (c) 2014-2017 The Dash Core developers
  // Copyright (c) 2018 The IQcash Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_VALIDATION_H
  #define BITCOIN_VALIDATION_H
  
  #if defined(HAVE_CONFIG_H)
  #include "config/iqcash-config.h"
  #endif
  
  #include "amount.h"
  #include "chain.h"
  #include "coins.h"
  #include "protocol.h" // For CMessageHeader::MessageStartChars
  #include "script/script_error.h"
  #include "sync.h"
  #include "versionbits.h"
  #include "spentindex.h"
  
  #include <algorithm>
  #include <exception>
  #include <map>
  #include <set>
  #include <stdint.h>
  #include <string>
  #include <utility>
  #include <vector>
  
  #include <atomic>
  
  #include <boost/unordered_map.hpp>
  #include <boost/filesystem/path.hpp>
  
  class CBlockIndex;
  class CBlockTreeDB;
  class CBloomFilter;
  class CChainParams;
  class CCoinsViewDB;
  class CInv;
  class CConnman;
  class CScriptCheck;
  class CTxMemPool;
  class CValidationInterface;
  class CValidationState;
  
  struct LockPoints;
  
  /** Default for accepting alerts from the P2P network. */
  static const bool DEFAULT_ALERTS = true;
  /** Default for DEFAULT_WHITELISTRELAY. */
  static const bool DEFAULT_WHITELISTRELAY = true;
  /** Default for DEFAULT_WHITELISTFORCERELAY. */
  static const bool DEFAULT_WHITELISTFORCERELAY = true;
  /** Default for -minrelaytxfee, minimum relay fee for transactions */
  static const unsigned int DEFAULT_MIN_RELAY_TX_FEE = 1000;
  /** Default for -maxorphantx, maximum number of orphan transactions kept in memory */
  static const unsigned int DEFAULT_MAX_ORPHAN_TRANSACTIONS = 100;
  /** Default for -limitancestorcount, max number of in-mempool ancestors */
  static const unsigned int DEFAULT_ANCESTOR_LIMIT = 25;
  /** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
  static const unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT = 101;
  /** Default for -limitdescendantcount, max number of in-mempool descendants */
  static const unsigned int DEFAULT_DESCENDANT_LIMIT = 25;
  /** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
  static const unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT = 101;
  /** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
  static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 72;
  /** The maximum size of a blk?????.dat file (since 0.8) */
  static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB
  /** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
  static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
  /** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
  static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
  
  /** Maximum number of script-checking threads allowed */
  static const int MAX_SCRIPTCHECK_THREADS = 16;
  /** -par default (number of script-checking threads, 0 = auto) */
  static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
  /** Number of blocks that can be requested at any given time from a single peer. */
  static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
  /** Timeout in seconds during which a peer must stall block download progress before being disconnected. */
  static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
  /** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
   *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
  static const unsigned int MAX_HEADERS_RESULTS = 2000;
  /** Size of the "block download window": how far ahead of our current height do we fetch?
   *  Larger windows tolerate larger download speed differences between peer, but increase the potential
   *  degree of disordering of blocks on disk (which make reindexing and in the future perhaps pruning
   *  harder). We'll probably want to make this a per-peer adaptive value at some point. */
  static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
  /** Time to wait (in seconds) between writing blocks/block index to disk. */
  static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
  /** Time to wait (in seconds) between flushing chainstate to disk. */
  static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
  /** Maximum length of reject messages. */
  static const unsigned int MAX_REJECT_MESSAGE_LENGTH = 111;
  /** Average delay between local address broadcasts in seconds. */
  static const unsigned int AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL = 24 * 24 * 60;
  /** Average delay between peer address broadcasts in seconds. */
  static const unsigned int AVG_ADDRESS_BROADCAST_INTERVAL = 30;
  /** Average delay between trickled inventory broadcasts in seconds.
   *  Blocks, whitelisted receivers, and a random 25% of transactions bypass this. */
  static const unsigned int AVG_INVENTORY_BROADCAST_INTERVAL = 5;
  /** Block download timeout base, expressed in millionths of the block interval (i.e. 2.5 min) */
  static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 250000;
  /** Additional block download timeout per parallel downloading peer (i.e. 1.25 min) */
  static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 125000;
  
  static const unsigned int DEFAULT_LIMITFREERELAY = 15;
  static const bool DEFAULT_RELAYPRIORITY = true;
  
  /** Default for -permitbaremultisig */
  static const bool DEFAULT_PERMIT_BAREMULTISIG = true;
  static const unsigned int DEFAULT_BYTES_PER_SIGOP = 20;
  static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
  static const bool DEFAULT_TXINDEX = true;
  static const bool DEFAULT_ADDRESSINDEX = false;
  static const bool DEFAULT_TIMESTAMPINDEX = false;
  static const bool DEFAULT_SPENTINDEX = false;
  static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
  
  static const bool DEFAULT_TESTSAFEMODE = false;
  /** Default for -mempoolreplacement */
  static const bool DEFAULT_ENABLE_REPLACEMENT = false;
  
  /** Maximum number of headers to announce when relaying blocks with headers message.*/
  static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
  
  struct BlockHasher
  {
      size_t operator()(const uint256& hash) const { return hash.GetCheapHash(); }
  };
  
  extern CScript COINBASE_FLAGS;
  extern CCriticalSection cs_main;
  extern CTxMemPool mempool;
  typedef boost::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
  extern BlockMap mapBlockIndex;
  extern uint64_t nLastBlockTx;
  extern uint64_t nLastBlockSize;
  extern const std::string strMessageMagic;
  extern CWaitableCriticalSection csBestBlock;
  extern CConditionVariable cvBlockChange;
  extern bool fImporting;
  extern bool fReindex;
  extern int nScriptCheckThreads;
  extern bool fTxIndex;
  extern bool fIsBareMultisigStd;
  extern bool fRequireStandard;
  extern unsigned int nBytesPerSigOp;
  extern bool fCheckBlockIndex;
  extern bool fCheckpointsEnabled;
  extern size_t nCoinCacheUsage;
  extern CFeeRate minRelayTxFee;
  extern bool fAlerts;
  extern bool fEnableReplacement;
  
  extern bool fLargeWorkForkFound;
  extern bool fLargeWorkInvalidChainFound;
  
  extern std::map<uint256, int64_t> mapRejectedBlocks;
  
  extern std::atomic<bool> fDIP0001WasLockedIn;
  extern std::atomic<bool> fDIP0001ActiveAtTip;
  
  /** Block hash whose ancestors we will assume to have valid scripts without checking them. */
  extern uint256 hashAssumeValid;
  
  /** Best header we've seen so far (used for getheaders queries' starting points). */
  extern CBlockIndex *pindexBestHeader;
  
  /** Minimum disk space required - used in CheckDiskSpace() */
  static const uint64_t nMinDiskSpace = 52428800;
  
  /** Pruning-related variables and constants */
  /** True if any block files have ever been pruned. */
  extern bool fHavePruned;
  /** True if we're running in -prune mode. */
  extern bool fPruneMode;
  /** Number of MiB of block files that we're trying to stay below. */
  extern uint64_t nPruneTarget;
  /** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of chainActive.Tip() will not be pruned. */
  static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
  
  static const signed int DEFAULT_CHECKBLOCKS = MIN_BLOCKS_TO_KEEP;
  static const unsigned int DEFAULT_CHECKLEVEL = 3;
  
  // Require that user allocate at least 945MB for block & undo files (blk???.dat and rev???.dat)
  // At 2MB per block, 288 blocks = 576MB.
  // Add 15% for Undo data = 662MB
  // Add 20% for Orphan block rate = 794MB
  // We want the low water mark after pruning to be at least 794 MB and since we prune in
  // full block file chunks, we need the high water mark which triggers the prune to be
  // one 128MB block file + added 15% undo data = 147MB greater for a total of 941MB
  // Setting the target to > than 945MB will make it likely we can respect the target.
  static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 945 * 1024 * 1024;
  
  /** 
   * Process an incoming block. This only returns after the best known valid
   * block is made active. Note that it does not, however, guarantee that the
   * specific block passed to it has been checked for validity!
   *
   * If you want to *possibly* get feedback on whether pblock is valid, you must
   * install a CValidationInterface (see validationinterface.h) - this will have
   * its BlockChecked method called whenever *any* block completes validation.
   *
   * Note that we guarantee that either the proof-of-work is valid on pblock, or
   * (and possibly also) BlockChecked will have been called.
   * 
   * @param[in]   pblock  The block we want to process.
   * @param[in]   fForceProcessing Process this block even if unrequested; used for non-network block sources and whitelisted peers.
   * @param[out]  dbp     The already known disk position of pblock, or NULL if not yet stored.
   * @param[out]  fNewBlock A boolean which is set to indicate if the block was first received via this call
   * @return True if state.IsValid()
   */
  bool ProcessNewBlock(const CChainParams& chainparams, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp, bool* fNewBlock);
  
  /**
   * Process incoming block headers.
   *
   * @param[in]  block The block headers themselves
   * @param[out] state This may be set to an Error state if any error occurred processing them
   * @param[in]  chainparams The params for the chain we want to connect to
   * @param[out] ppindex If set, the pointer will be set to point to the last new block index object for the given headers
   */
  bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex=NULL);
  
  /** Check whether enough disk space is available for an incoming block */
  bool CheckDiskSpace(uint64_t nAdditionalBytes = 0);
  /** Open a block file (blk?????.dat) */
  FILE* OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly = false);
  /** Open an undo file (rev?????.dat) */
  FILE* OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly = false);
  /** Translation to a filesystem path */
  boost::filesystem::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix);
  /** Import blocks from an external file */
  bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskBlockPos *dbp = NULL);
  /** Initialize a new block tree database + block data on disk */
  bool InitBlockIndex(const CChainParams& chainparams);
  /** Load the block tree and coins database from disk */
  bool LoadBlockIndex();
  /** Unload database information */
  void UnloadBlockIndex();
  /** Run an instance of the script checking thread */
  void ThreadScriptCheck();
  /** Check whether we are doing an initial block download (synchronizing from disk or network) */
  bool IsInitialBlockDownload();
  /** Format a string that describes several potential problems detected by the core.
   * strFor can have three values:
   * - "rpc": get critical warnings, which should put the client in safe mode if non-empty
   * - "statusbar": get all warnings
   * - "gui": get all warnings, translated (where possible) for GUI
   * This function only returns the highest priority warning of the set selected by strFor.
   */
  std::string GetWarnings(const std::string& strFor);
  /** Retrieve a transaction (from memory pool, or from disk, if possible) */
  bool GetTransaction(const uint256 &hash, CTransaction &tx, const Consensus::Params& params, uint256 &hashBlock, bool fAllowSlow = false);
  /** Find the best known block, and make it the tip of the block chain */
  bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams, const CBlock* pblock = NULL);
  
  double ConvertBitsToDouble(unsigned int nBits);
  CAmount GetBlockSubsidy(int nBits, int nHeight, const Consensus::Params& consensusParams, bool fSuperblockPartOnly = false);
  CAmount GetMasternodePayment(int nHeight, CAmount blockValue);
  
  /**
   * Prune block and undo files (blk???.dat and undo???.dat) so that the disk space used is less than a user-defined target.
   * The user sets the target (in MB) on the command line or in config file.  This will be run on startup and whenever new
   * space is allocated in a block or undo file, staying below the target. Changing back to unpruned requires a reindex
   * (which in this case means the blockchain must be re-downloaded.)
   *
   * Pruning functions are called from FlushStateToDisk when the global fCheckForPruning flag has been set.
   * Block and undo files are deleted in lock-step (when blk00003.dat is deleted, so is rev00003.dat.)
   * Pruning cannot take place until the longest chain is at least a certain length (100000 on mainnet, 1000 on testnet, 1000 on regtest).
   * Pruning will never delete a block within a defined distance (currently 288) from the active chain's tip.
   * The block index is updated by unsetting HAVE_DATA and HAVE_UNDO for any blocks that were stored in the deleted files.
   * A db flag records the fact that at least some block files have been pruned.
   *
   * @param[out]   setFilesToPrune   The set of file indices that can be unlinked will be returned
   */
  void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight);
  
  /**
   *  Actually unlink the specified files
   */
  void UnlinkPrunedFiles(std::set<int>& setFilesToPrune);
  
  /** Create a new block index entry for a given block hash */
  CBlockIndex * InsertBlockIndex(uint256 hash);
  /** Flush all state, indexes and buffers to disk. */
  void FlushStateToDisk();
  /** Prune block files and flush state to disk. */
  void PruneAndFlush();
  
  /** (try to) add transaction to memory pool **/
  bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
                          bool* pfMissingInputs, bool fOverrideMempoolLimit=false, bool fRejectAbsurdFee=false, bool fDryRun=false);
  
  bool GetUTXOCoin(const COutPoint& outpoint, Coin& coin);
  int GetUTXOHeight(const COutPoint& outpoint);
  int GetUTXOConfirmations(const COutPoint& outpoint);
  
  /** Convert CValidationState to a human-readable message for logging */
  std::string FormatStateMessage(const CValidationState &state);
  
  /** Get the BIP9 state for a given deployment at the current tip. */
  ThresholdState VersionBitsTipState(const Consensus::Params& params, Consensus::DeploymentPos pos);
  
  /**
   * Count ECDSA signature operations the old-fashioned (pre-0.6) way
   * @return number of sigops this transaction's outputs will produce when spent
   * @see CTransaction::FetchInputs
   */
  unsigned int GetLegacySigOpCount(const CTransaction& tx);
  
  /**
   * Count ECDSA signature operations in pay-to-script-hash inputs.
   * 
   * @param[in] mapInputs Map of previous transactions that have outputs we're spending
   * @return maximum number of sigops required to validate this transaction's inputs
   * @see CTransaction::FetchInputs
   */
  unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& mapInputs);
  
  
  /**
   * Check whether all inputs of this transaction are valid (no double spends, scripts & sigs, amounts)
   * This does not modify the UTXO set. If pvChecks is not NULL, script checks are pushed onto it
   * instead of being performed inline.
   */
  bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &view, bool fScriptChecks,
                   unsigned int flags, bool cacheStore, std::vector<CScriptCheck> *pvChecks = NULL);
  
  /** Apply the effects of this transaction on the UTXO set represented by view */
  void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCache &inputs, int nHeight);
  
  /** Context-independent validity checks */
  bool CheckTransaction(const CTransaction& tx, CValidationState& state);
  
  /**
   * Check if transaction is final and can be included in a block with the
   * specified height and time. Consensus critical.
   */
  bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime);
  
  /**
   * Check if transaction will be final in the next block to be created.
   *
   * Calls IsFinalTx() with current block height and appropriate block time.
   *
   * See consensus/consensus.h for flag definitions.
   */
  bool CheckFinalTx(const CTransaction &tx, int flags = -1);
  
  /**
   * Test whether the LockPoints height and time are still valid on the current chain
   */
  bool TestLockPointValidity(const LockPoints* lp);
  
  /**
   * Check if transaction is final per BIP 68 sequence numbers and can be included in a block.
   * Consensus critical. Takes as input a list of heights at which tx's inputs (in order) confirmed.
   */
  bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block);
  
  /**
   * Check if transaction will be BIP 68 final in the next block to be created.
   *
   * Simulates calling SequenceLocks() with data from the tip of the current active chain.
   * Optionally stores in LockPoints the resulting height and time calculated and the hash
   * of the block needed for calculation or skips the calculation and uses the LockPoints
   * passed in for evaluation.
   * The LockPoints should not be considered valid if CheckSequenceLocks returns false.
   *
   * See consensus/consensus.h for flag definitions.
   */
  bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp = NULL, bool useExistingLockPoints = false);
  
  /**
   * Closure representing one script verification
   * Note that this stores references to the spending transaction 
   */
  class CScriptCheck
  {
  private:
      CScript scriptPubKey;
      const CTransaction *ptxTo;
      unsigned int nIn;
      unsigned int nFlags;
      bool cacheStore;
      ScriptError error;
  
  public:
      CScriptCheck(): ptxTo(0), nIn(0), nFlags(0), cacheStore(false), error(SCRIPT_ERR_UNKNOWN_ERROR) {}
      CScriptCheck(const CScript& scriptPubKeyIn, const CAmount amountIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, bool cacheIn) :
          scriptPubKey(scriptPubKeyIn),
          ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn), error(SCRIPT_ERR_UNKNOWN_ERROR) { }
  
      bool operator()();
  
      void swap(CScriptCheck &check) {
          scriptPubKey.swap(check.scriptPubKey);
          std::swap(ptxTo, check.ptxTo);
          std::swap(nIn, check.nIn);
          std::swap(nFlags, check.nFlags);
          std::swap(cacheStore, check.cacheStore);
          std::swap(error, check.error);
      }
  
      ScriptError GetScriptError() const { return error; }
  };
  
  bool GetTimestampIndex(const unsigned int &high, const unsigned int &low, std::vector<uint256> &hashes);
  bool GetSpentIndex(CSpentIndexKey &key, CSpentIndexValue &value);
  bool GetAddressIndex(uint160 addressHash, int type,
                       std::vector<std::pair<CAddressIndexKey, CAmount> > &addressIndex,
                       int start = 0, int end = 0);
  bool GetAddressUnspent(uint160 addressHash, int type,
                         std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > &unspentOutputs);
  
  /** Functions for disk access for blocks */
  bool WriteBlockToDisk(const CBlock& block, CDiskBlockPos& pos, const CMessageHeader::MessageStartChars& messageStart);
  bool ReadBlockFromDisk(CBlock& block, const CDiskBlockPos& pos, const Consensus::Params& consensusParams);
  bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex, const Consensus::Params& consensusParams);
  
  /** Functions for validating blocks and updating the block tree */
  
  /** Reprocess a number of blocks to try and get on the correct chain again **/
  bool DisconnectBlocks(int blocks);
  void ReprocessBlocks(int nBlocks);
  
  /** Context-independent validity checks */
  bool CheckBlockHeader(const CBlockHeader& block, CValidationState& state, bool fCheckPOW = true);
  bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW = true, bool fCheckMerkleRoot = true);
  
  /** Context-dependent validity checks */
  bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex *pindexPrev);
  bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIndex *pindexPrev);
  
  /** Check a block is completely valid from start to finish (only works on top of our current best block, with cs_main held) */
  bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams, const CBlock& block, CBlockIndex* pindexPrev, bool fCheckPOW = true, bool fCheckMerkleRoot = true);
  
  /** RAII wrapper for VerifyDB: Verify consistency of the block and coin databases */
  class CVerifyDB {
  public:
      CVerifyDB();
      ~CVerifyDB();
      bool VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview, int nCheckLevel, int nCheckDepth);
  };
  
  /** Find the last common block between the parameter chain and a locator. */
  CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator);
  
  /** Mark a block as invalid. */
  bool InvalidateBlock(CValidationState& state, const Consensus::Params& consensusParams, CBlockIndex *pindex);
  
  /** Remove invalidity status from a block and its descendants. */
  bool ReconsiderBlock(CValidationState& state, CBlockIndex *pindex);
  
  /** The currently-connected chain of blocks (protected by cs_main). */
  extern CChain chainActive;
  
  /** Global variable that points to the coins database (protected by cs_main) */
  extern CCoinsViewDB *pcoinsdbview;
  
  /** Global variable that points to the active CCoinsView (protected by cs_main) */
  extern CCoinsViewCache *pcoinsTip;
  
  /** Global variable that points to the active block tree (protected by cs_main) */
  extern CBlockTreeDB *pblocktree;
  
  /**
   * Return the spend height, which is one more than the inputs.GetBestBlock().
   * While checking, GetBestBlock() refers to the parent block. (protected by cs_main)
   * This is also true for mempool checks.
   */
  int GetSpendHeight(const CCoinsViewCache& inputs);
  
  extern VersionBitsCache versionbitscache;
  
  /**
   * Determine what nVersion a new block should use.
   */
  int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params, bool fAssumeMasternodeIsUpgraded = false);
  
  /**
   * Return true if hash can be found in chainActive at nBlockHeight height.
   * Fills hashRet with found hash, if no nBlockHeight is specified - chainActive.Height() is used.
   */
  bool GetBlockHash(uint256& hashRet, int nBlockHeight = -1);
  
  /** Reject codes greater or equal to this can be returned by AcceptToMemPool
   * for transactions, to signal internal conditions. They cannot and should not
   * be sent over the P2P network.
   */
  static const unsigned int REJECT_INTERNAL = 0x100;
  /** Too high fee. Can not be triggered by P2P transactions */
  static const unsigned int REJECT_HIGHFEE = 0x100;
  /** Transaction is already known (either in mempool or blockchain) */
  static const unsigned int REJECT_ALREADY_KNOWN = 0x101;
  /** Transaction conflicts with a transaction already known */
  static const unsigned int REJECT_CONFLICT = 0x102;
  
  #endif // BITCOIN_VALIDATION_H
  