main.h

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_MAIN_H
#define BITCOIN_MAIN_H

#if defined(HAVE_CONFIG_H)
#include "config/bitcoin-config.h"
#endif

#include "amount.h"
#include "chain.h"
#include "chainparams.h"
#include "coins.h"
#include "core/block.h"
#include "core/transaction.h"
#include "net.h"
#include "pow.h"
#include "script/script.h"
#include "script/sigcache.h"
#include "script/standard.h"
#include "sync.h"
#include "tinyformat.h"
#include "txmempool.h"
#include "uint256.h"
#include "undo.h"

#include <algorithm>
#include <exception>
#include <map>
#include <set>
#include <stdint.h>
#include <string>
#include <utility>
#include <vector>

#include <boost/unordered_map.hpp>

class CBlockIndex;
class CBlockTreeDB;
class CBloomFilter;
class CInv;
class CScriptCheck;
class CValidationInterface;
class CValidationState;

struct CBlockTemplate;
struct CNodeStateStats;

/** The maximum allowed size for a serialized block, in bytes (network rule) */
static const unsigned int MAX_BLOCK_SIZE = 1000000;
/** Default for -blockmaxsize and -blockminsize, which control the range of sizes the mining code will create **/
static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
static const unsigned int DEFAULT_BLOCK_MIN_SIZE = 0;
/** Default for -blockprioritysize, maximum space for zero/low-fee transactions **/
static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 50000;
/** The maximum size for transactions we're willing to relay/mine */
static const unsigned int MAX_STANDARD_TX_SIZE = 100000;
/** The maximum allowed number of signature check operations in a block (network rule) */
static const unsigned int MAX_BLOCK_SIGOPS = MAX_BLOCK_SIZE/50;
/** Maxiumum number of signature check operations in an IsStandard() P2SH script */
static const unsigned int MAX_P2SH_SIGOPS = 15;
/** The maximum number of sigops we're willing to relay/mine in a single tx */
static const unsigned int MAX_TX_SIGOPS = MAX_BLOCK_SIGOPS/5;
/** Default for -maxorphantx, maximum number of orphan transactions kept in memory */
static const unsigned int DEFAULT_MAX_ORPHAN_TRANSACTIONS = 100;
/** Default for -maxorphanblocks, maximum number of orphan blocks kept in memory */
static const unsigned int DEFAULT_MAX_ORPHAN_BLOCKS = 750;
/** 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
/** Coinbase transaction outputs can only be spent after this number of new blocks (network rule) */
static const int COINBASE_MATURITY = 100;
/** Threshold for nLockTime: below this value it is interpreted as block number, otherwise as UNIX timestamp. */
static const unsigned int LOCKTIME_THRESHOLD = 500000000; // Tue Nov  5 00:53:20 1985 UTC
/** 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 their 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 blockchain state to disk. */
static const unsigned int DATABASE_WRITE_INTERVAL = 3600;

/** "reject" message codes **/
static const unsigned char REJECT_MALFORMED = 0x01;
static const unsigned char REJECT_INVALID = 0x10;
static const unsigned char REJECT_OBSOLETE = 0x11;
static const unsigned char REJECT_DUPLICATE = 0x12;
static const unsigned char REJECT_NONSTANDARD = 0x40;
static const unsigned char REJECT_DUST = 0x41;
static const unsigned char REJECT_INSUFFICIENTFEE = 0x42;
static const unsigned char REJECT_CHECKPOINT = 0x43;

struct BlockHasher
{
    size_t operator()(const uint256& hash) const { return hash.GetLow64(); }
};

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 int64_t nTimeBestReceived;
extern CWaitableCriticalSection csBestBlock;
extern CConditionVariable cvBlockChange;
extern bool fImporting;
extern bool fReindex;
extern int nScriptCheckThreads;
extern bool fTxIndex;
extern bool fIsBareMultisigStd;
extern unsigned int nCoinCacheSize;
extern CFeeRate minRelayTxFee;

// 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;

/** Register a wallet to receive updates from core */
void RegisterValidationInterface(CValidationInterface* pwalletIn);
/** Unregister a wallet from core */
void UnregisterValidationInterface(CValidationInterface* pwalletIn);
/** Unregister all wallets from core */
void UnregisterAllValidationInterfaces();
/** Push an updated transaction to all registered wallets */
void SyncWithWallets(const CTransaction& tx, const CBlock* pblock = NULL);

/** Register with a network node to receive its signals */
void RegisterNodeSignals(CNodeSignals& nodeSignals);
/** Unregister a network node */
void UnregisterNodeSignals(CNodeSignals& nodeSignals);

/** 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!
    @param[out]  state   This may be set to an Error state if any error occurred processing it, including during validation/connection/etc of otherwise unrelated blocks during reorganisation; or it may be set to an Invalid state iff pblock is itself invalid (but this is not guaranteed even when the block is checked). If you want to *possibly* get feedback on whether pblock is valid, you must also install a CValidationInterface - this will have its BlockChecked method called whenever *any* block completes validation.
    @param[in]   pfrom   The node which we are receiving the block from; it is added to mapBlockSource and may be penalised if the block is invalid.
    @param[in]   pblock  The block we want to process.
    @param[out]  dbp     If pblock is stored to disk (or already there), this will be set to its location.
    @return True if state.IsValid()
*/
bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, CDiskBlockPos *dbp = 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(FILE* fileIn, CDiskBlockPos *dbp = NULL);
/** Initialize a new block tree database + block data on disk */
bool InitBlockIndex();
/** Load the block tree and coins database from disk */
bool LoadBlockIndex();
/** Unload database information */
void UnloadBlockIndex();
/** Print the loaded block tree */
void PrintBlockTree();
/** Process protocol messages received from a given node */
bool ProcessMessages(CNode* pfrom);
/** Send queued protocol messages to be sent to a give node */
bool SendMessages(CNode* pto, bool fSendTrickle);
/** 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 */
std::string GetWarnings(std::string strFor);
/** Retrieve a transaction (from memory pool, or from disk, if possible) */
bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, bool fAllowSlow = false);
/** Find the best known block, and make it the tip of the block chain */
bool ActivateBestChain(CValidationState &state, CBlock *pblock = NULL);
CAmount GetBlockValue(int nHeight, const CAmount& nFees);

/** Create a new block index entry for a given block hash */
CBlockIndex * InsertBlockIndex(uint256 hash);
/** Abort with a message */
bool AbortNode(const std::string &msg, const std::string &userMessage="");
/** Get statistics from node state */
bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats);
/** Increase a node's misbehavior score. */
void Misbehaving(NodeId nodeid, int howmuch);
/** Flush all state, indexes and buffers to disk. */
void FlushStateToDisk();


/** (try to) add transaction to memory pool **/
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
                        bool* pfMissingInputs, bool fRejectInsaneFee=false);


struct CNodeStateStats {
    int nMisbehavior;
    int nSyncHeight;
    int nCommonHeight;
    std::vector<int> vHeightInFlight;
};

struct CDiskTxPos : public CDiskBlockPos
{
    unsigned int nTxOffset; // after header

    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        READWRITE(*(CDiskBlockPos*)this);
        READWRITE(VARINT(nTxOffset));
    }

    CDiskTxPos(const CDiskBlockPos &blockIn, unsigned int nTxOffsetIn) : CDiskBlockPos(blockIn.nFile, blockIn.nPos), nTxOffset(nTxOffsetIn) {
    }

    CDiskTxPos() {
        SetNull();
    }

    void SetNull() {
        CDiskBlockPos::SetNull();
        nTxOffset = 0;
    }
};


CAmount GetMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree);

//
// Check transaction inputs, and make sure any
// pay-to-script-hash transactions are evaluating IsStandard scripts
//
// Why bother? To avoid denial-of-service attacks; an attacker
// can submit a standard HASH... OP_EQUAL transaction,
// which will get accepted into blocks. The redemption
// script can be anything; an attacker could use a very
// expensive-to-check-upon-redemption script like:
//   DUP CHECKSIG DROP ... repeated 100 times... OP_1
//

/** Check for standard transaction types
    @param[in] mapInputs    Map of previous transactions that have outputs we're spending
    @return True if all inputs (scriptSigs) use only standard transaction forms
*/
bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);

/** 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, CTxUndo &txundo, int nHeight);

// Context-independent validity checks
bool CheckTransaction(const CTransaction& tx, CValidationState& state);

/** Check for standard transaction types
    @return True if all outputs (scriptPubKeys) use only standard transaction forms
*/
bool IsStandardTx(const CTransaction& tx, std::string& reason);

bool IsFinalTx(const CTransaction &tx, int nBlockHeight = 0, int64_t nBlockTime = 0);

/** Undo information for a CBlock */
class CBlockUndo
{
public:
    std::vector<CTxUndo> vtxundo; // for all but the coinbase

    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        READWRITE(vtxundo);
    }

    bool WriteToDisk(CDiskBlockPos &pos, const uint256 &hashBlock);
    bool ReadFromDisk(const CDiskBlockPos &pos, const uint256 &hashBlock);
};


/** 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;

public:
    CScriptCheck(): ptxTo(0), nIn(0), nFlags(0), cacheStore(false) {}
    CScriptCheck(const CCoins& txFromIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, bool cacheIn) :
        scriptPubKey(txFromIn.vout[txToIn.vin[nInIn].prevout.n].scriptPubKey),
        ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn) { }

    bool operator()() const;

    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);
    }
};

/** Data structure that represents a partial merkle tree.
 *
 * It respresents a subset of the txid's of a known block, in a way that
 * allows recovery of the list of txid's and the merkle root, in an
 * authenticated way.
 *
 * The encoding works as follows: we traverse the tree in depth-first order,
 * storing a bit for each traversed node, signifying whether the node is the
 * parent of at least one matched leaf txid (or a matched txid itself). In
 * case we are at the leaf level, or this bit is 0, its merkle node hash is
 * stored, and its children are not explorer further. Otherwise, no hash is
 * stored, but we recurse into both (or the only) child branch. During
 * decoding, the same depth-first traversal is performed, consuming bits and
 * hashes as they written during encoding.
 *
 * The serialization is fixed and provides a hard guarantee about the
 * encoded size:
 *
 *   SIZE <= 10 + ceil(32.25*N)
 *
 * Where N represents the number of leaf nodes of the partial tree. N itself
 * is bounded by:
 *
 *   N <= total_transactions
 *   N <= 1 + matched_transactions*tree_height
 *
 * The serialization format:
 *  - uint32     total_transactions (4 bytes)
 *  - varint     number of hashes   (1-3 bytes)
 *  - uint256[]  hashes in depth-first order (<= 32*N bytes)
 *  - varint     number of bytes of flag bits (1-3 bytes)
 *  - byte[]     flag bits, packed per 8 in a byte, least significant bit first (<= 2*N-1 bits)
 * The size constraints follow from this.
 */
class CPartialMerkleTree
{
protected:
    // the total number of transactions in the block
    unsigned int nTransactions;

    // node-is-parent-of-matched-txid bits
    std::vector<bool> vBits;

    // txids and internal hashes
    std::vector<uint256> vHash;

    // flag set when encountering invalid data
    bool fBad;

    // helper function to efficiently calculate the number of nodes at given height in the merkle tree
    unsigned int CalcTreeWidth(int height) {
        return (nTransactions+(1 << height)-1) >> height;
    }

    // calculate the hash of a node in the merkle tree (at leaf level: the txid's themself)
    uint256 CalcHash(int height, unsigned int pos, const std::vector<uint256> &vTxid);

    // recursive function that traverses tree nodes, storing the data as bits and hashes
    void TraverseAndBuild(int height, unsigned int pos, const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);

    // recursive function that traverses tree nodes, consuming the bits and hashes produced by TraverseAndBuild.
    // it returns the hash of the respective node.
    uint256 TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch);

public:

    // serialization implementation
    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        READWRITE(nTransactions);
        READWRITE(vHash);
        std::vector<unsigned char> vBytes;
        if (ser_action.ForRead()) {
            READWRITE(vBytes);
            CPartialMerkleTree &us = *(const_cast<CPartialMerkleTree*>(this));
            us.vBits.resize(vBytes.size() * 8);
            for (unsigned int p = 0; p < us.vBits.size(); p++)
                us.vBits[p] = (vBytes[p / 8] & (1 << (p % 8))) != 0;
            us.fBad = false;
        } else {
            vBytes.resize((vBits.size()+7)/8);
            for (unsigned int p = 0; p < vBits.size(); p++)
                vBytes[p / 8] |= vBits[p] << (p % 8);
            READWRITE(vBytes);
        }
    }

    // Construct a partial merkle tree from a list of transaction id's, and a mask that selects a subset of them
    CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);

    CPartialMerkleTree();

    // extract the matching txid's represented by this partial merkle tree.
    // returns the merkle root, or 0 in case of failure
    uint256 ExtractMatches(std::vector<uint256> &vMatch);
};



/** Functions for disk access for blocks */
bool WriteBlockToDisk(CBlock& block, CDiskBlockPos& pos);
bool ReadBlockFromDisk(CBlock& block, const CDiskBlockPos& pos);
bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex);


/** Functions for validating blocks and updating the block tree */

/** Undo the effects of this block (with given index) on the UTXO set represented by coins.
 *  In case pfClean is provided, operation will try to be tolerant about errors, and *pfClean
 *  will be true if no problems were found. Otherwise, the return value will be false in case
 *  of problems. Note that in any case, coins may be modified. */
bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, CCoinsViewCache& coins, bool* pfClean = NULL);

// Apply the effects of this block (with given index) on the UTXO set represented by coins
bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex, CCoinsViewCache& coins, bool fJustCheck = false);

// 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 CBlock& block, CBlockIndex *pindexPrev, bool fCheckPOW = true, bool fCheckMerkleRoot = true);

// Store block on disk
// if dbp is provided, the file is known to already reside on disk
bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex **pindex, CDiskBlockPos* dbp = NULL);
bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex **ppindex= NULL);



class CBlockFileInfo
{
public:
    unsigned int nBlocks;      // number of blocks stored in file
    unsigned int nSize;        // number of used bytes of block file
    unsigned int nUndoSize;    // number of used bytes in the undo file
    unsigned int nHeightFirst; // lowest height of block in file
    unsigned int nHeightLast;  // highest height of block in file
    uint64_t nTimeFirst;         // earliest time of block in file
    uint64_t nTimeLast;          // latest time of block in file

    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        READWRITE(VARINT(nBlocks));
        READWRITE(VARINT(nSize));
        READWRITE(VARINT(nUndoSize));
        READWRITE(VARINT(nHeightFirst));
        READWRITE(VARINT(nHeightLast));
        READWRITE(VARINT(nTimeFirst));
        READWRITE(VARINT(nTimeLast));
    }

     void SetNull() {
         nBlocks = 0;
         nSize = 0;
         nUndoSize = 0;
         nHeightFirst = 0;
         nHeightLast = 0;
         nTimeFirst = 0;
         nTimeLast = 0;
     }

     CBlockFileInfo() {
         SetNull();
     }

     std::string ToString() const;

     // update statistics (does not update nSize)
     void AddBlock(unsigned int nHeightIn, uint64_t nTimeIn) {
         if (nBlocks==0 || nHeightFirst > nHeightIn)
             nHeightFirst = nHeightIn;
         if (nBlocks==0 || nTimeFirst > nTimeIn)
             nTimeFirst = nTimeIn;
         nBlocks++;
         if (nHeightIn > nHeightLast)
             nHeightLast = nHeightIn;
         if (nTimeIn > nTimeLast)
             nTimeLast = nTimeIn;
     }
};

/** Capture information about block/transaction validation */
class CValidationState {
private:
    enum mode_state {
        MODE_VALID,   // everything ok
        MODE_INVALID, // network rule violation (DoS value may be set)
        MODE_ERROR,   // run-time error
    } mode;
    int nDoS;
    std::string strRejectReason;
    unsigned char chRejectCode;
    bool corruptionPossible;
public:
    CValidationState() : mode(MODE_VALID), nDoS(0), chRejectCode(0), corruptionPossible(false) {}
    bool DoS(int level, bool ret = false,
             unsigned char chRejectCodeIn=0, std::string strRejectReasonIn="",
             bool corruptionIn=false) {
        chRejectCode = chRejectCodeIn;
        strRejectReason = strRejectReasonIn;
        corruptionPossible = corruptionIn;
        if (mode == MODE_ERROR)
            return ret;
        nDoS += level;
        mode = MODE_INVALID;
        return ret;
    }
    bool Invalid(bool ret = false,
                 unsigned char _chRejectCode=0, std::string _strRejectReason="") {
        return DoS(0, ret, _chRejectCode, _strRejectReason);
    }
    bool Error(std::string strRejectReasonIn="") {
        if (mode == MODE_VALID)
            strRejectReason = strRejectReasonIn;
        mode = MODE_ERROR;
        return false;
    }
    bool Abort(const std::string &msg) {
        AbortNode(msg);
        return Error(msg);
    }
    bool IsValid() const {
        return mode == MODE_VALID;
    }
    bool IsInvalid() const {
        return mode == MODE_INVALID;
    }
    bool IsError() const {
        return mode == MODE_ERROR;
    }
    bool IsInvalid(int &nDoSOut) const {
        if (IsInvalid()) {
            nDoSOut = nDoS;
            return true;
        }
        return false;
    }
    bool CorruptionPossible() const {
        return corruptionPossible;
    }
    unsigned char GetRejectCode() const { return chRejectCode; }
    std::string GetRejectReason() const { return strRejectReason; }
};

/** RAII wrapper for VerifyDB: Verify consistency of the block and coin databases */
class CVerifyDB {
public:
    CVerifyDB();
    ~CVerifyDB();
    bool VerifyDB(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);

/** The currently-connected chain of blocks. */
extern CChain chainActive;

/** 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;

struct CBlockTemplate
{
    CBlock block;
    std::vector<CAmount> vTxFees;
    std::vector<int64_t> vTxSigOps;
};






/** Used to relay blocks as header + vector<merkle branch>
 * to filtered nodes.
 */
class CMerkleBlock
{
public:
    // Public only for unit testing
    CBlockHeader header;
    CPartialMerkleTree txn;

public:
    // Public only for unit testing and relay testing
    // (not relayed)
    std::vector<std::pair<unsigned int, uint256> > vMatchedTxn;

    // Create from a CBlock, filtering transactions according to filter
    // Note that this will call IsRelevantAndUpdate on the filter for each transaction,
    // thus the filter will likely be modified.
    CMerkleBlock(const CBlock& block, CBloomFilter& filter);

    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
        READWRITE(header);
        READWRITE(txn);
    }
};


class CValidationInterface {
protected:
    virtual void SyncTransaction(const CTransaction &tx, const CBlock *pblock) {};
    virtual void EraseFromWallet(const uint256 &hash) {};
    virtual void SetBestChain(const CBlockLocator &locator) {};
    virtual void UpdatedTransaction(const uint256 &hash) {};
    virtual void Inventory(const uint256 &hash) {};
    virtual void ResendWalletTransactions() {};
    virtual void BlockChecked(const CBlock&, const CValidationState&) {};
    friend void ::RegisterValidationInterface(CValidationInterface*);
    friend void ::UnregisterValidationInterface(CValidationInterface*);
    friend void ::UnregisterAllValidationInterfaces();
};

#endif // BITCOIN_MAIN_H