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bitcoin/src/chain.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_CHAIN_H
#define BITCOIN_CHAIN_H
#include <arith_uint256.h>
#include <consensus/params.h>
#include <flatfile.h>
#include <kernel/cs_main.h>
#include <primitives/block.h>
#include <serialize.h>
#include <sync.h>
#include <uint256.h>
#include <util/time.h>
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <string>
#include <vector>
/**
* Maximum amount of time that a block timestamp is allowed to exceed the
* current time before the block will be accepted.
*/
static constexpr int64_t MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60;
/**
* Timestamp window used as a grace period by code that compares external
* timestamps (such as timestamps passed to RPCs, or wallet key creation times)
* to block timestamps. This should be set at least as high as
* MAX_FUTURE_BLOCK_TIME.
*/
static constexpr int64_t TIMESTAMP_WINDOW = MAX_FUTURE_BLOCK_TIME;
/**
* Maximum gap between node time and block time used
* for the "Catching up..." mode in GUI.
*
* Ref: https://github.com/bitcoin/bitcoin/pull/1026
*/
static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
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
SERIALIZE_METHODS(CBlockFileInfo, obj)
{
READWRITE(VARINT(obj.nBlocks));
READWRITE(VARINT(obj.nSize));
READWRITE(VARINT(obj.nUndoSize));
READWRITE(VARINT(obj.nHeightFirst));
READWRITE(VARINT(obj.nHeightLast));
READWRITE(VARINT(obj.nTimeFirst));
READWRITE(VARINT(obj.nTimeLast));
}
CBlockFileInfo() {}
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;
}
};
enum BlockStatus : uint32_t {
//! Unused.
BLOCK_VALID_UNKNOWN = 0,
//! Reserved (was BLOCK_VALID_HEADER).
BLOCK_VALID_RESERVED = 1,
//! All parent headers found, difficulty matches, timestamp >= median previous, checkpoint. Implies all parents
//! are also at least TREE.
BLOCK_VALID_TREE = 2,
/**
* Only first tx is coinbase, 2 <= coinbase input script length <= 100, transactions valid, no duplicate txids,
* sigops, size, merkle root. Implies all parents are at least TREE but not necessarily TRANSACTIONS.
*
* If a block's validity is at least VALID_TRANSACTIONS, CBlockIndex::nTx will be set. If a block and all previous
* blocks back to the genesis block or an assumeutxo snapshot block are at least VALID_TRANSACTIONS,
* CBlockIndex::nChainTx will be set.
*/
BLOCK_VALID_TRANSACTIONS = 3,
//! Outputs do not overspend inputs, no double spends, coinbase output ok, no immature coinbase spends, BIP30.
//! Implies all previous blocks back to the genesis block or an assumeutxo snapshot block are at least VALID_CHAIN.
BLOCK_VALID_CHAIN = 4,
//! Scripts & signatures ok. Implies all previous blocks back to the genesis block or an assumeutxo snapshot block
//! are at least VALID_SCRIPTS.
BLOCK_VALID_SCRIPTS = 5,
//! All validity bits.
BLOCK_VALID_MASK = BLOCK_VALID_RESERVED | BLOCK_VALID_TREE | BLOCK_VALID_TRANSACTIONS |
BLOCK_VALID_CHAIN | BLOCK_VALID_SCRIPTS,
BLOCK_HAVE_DATA = 8, //!< full block available in blk*.dat
BLOCK_HAVE_UNDO = 16, //!< undo data available in rev*.dat
BLOCK_HAVE_MASK = BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
BLOCK_FAILED_VALID = 32, //!< stage after last reached validness failed
BLOCK_FAILED_CHILD = 64, //!< descends from failed block
BLOCK_FAILED_MASK = BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
BLOCK_OPT_WITNESS = 128, //!< block data in blk*.dat was received with a witness-enforcing client
/**
* If ASSUMED_VALID is set, it means that this block has not been validated
* and has validity status less than VALID_SCRIPTS. Also that it may have
* descendant blocks with VALID_SCRIPTS set, because they can be validated
* based on an assumeutxo snapshot.
*
* When an assumeutxo snapshot is loaded, the ASSUMED_VALID flag is added to
* unvalidated blocks at the snapshot height and below. Then, as the background
* validation progresses, and these blocks are validated, the ASSUMED_VALID
* flags are removed. See `doc/design/assumeutxo.md` for details.
*
* This flag is only used to implement checks in CheckBlockIndex() and
* should not be used elsewhere.
*/
BLOCK_ASSUMED_VALID = 256,
};
/** The block chain is a tree shaped structure starting with the
* genesis block at the root, with each block potentially having multiple
* candidates to be the next block. A blockindex may have multiple pprev pointing
* to it, but at most one of them can be part of the currently active branch.
*/
class CBlockIndex
{
public:
//! pointer to the hash of the block, if any. Memory is owned by this CBlockIndex
const uint256* phashBlock{nullptr};
//! pointer to the index of the predecessor of this block
CBlockIndex* pprev{nullptr};
//! pointer to the index of some further predecessor of this block
CBlockIndex* pskip{nullptr};
//! height of the entry in the chain. The genesis block has height 0
int nHeight{0};
//! Which # file this block is stored in (blk?????.dat)
int nFile GUARDED_BY(::cs_main){0};
//! Byte offset within blk?????.dat where this block's data is stored
unsigned int nDataPos GUARDED_BY(::cs_main){0};
//! Byte offset within rev?????.dat where this block's undo data is stored
unsigned int nUndoPos GUARDED_BY(::cs_main){0};
//! (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
arith_uint256 nChainWork{};
//! Number of transactions in this block. This will be nonzero if the block
//! reached the VALID_TRANSACTIONS level, and zero otherwise.
//! Note: in a potential headers-first mode, this number cannot be relied upon
unsigned int nTx{0};
//! (memory only) Number of transactions in the chain up to and including this block.
//! This value will be non-zero if this block and all previous blocks back
//! to the genesis block or an assumeutxo snapshot block have reached the
//! VALID_TRANSACTIONS level.
//! Change to 64-bit type before 2024 (assuming worst case of 60 byte transactions).
unsigned int nChainTx{0};
//! Verification status of this block. See enum BlockStatus
//!
//! Note: this value is modified to show BLOCK_OPT_WITNESS during UTXO snapshot
//! load to avoid the block index being spuriously rewound.
//! @sa NeedsRedownload
//! @sa ActivateSnapshot
uint32_t nStatus GUARDED_BY(::cs_main){0};
//! block header
int32_t nVersion{0};
uint256 hashMerkleRoot{};
uint32_t nTime{0};
uint32_t nBits{0};
uint32_t nNonce{0};
//! (memory only) Sequential id assigned to distinguish order in which blocks are received.
int32_t nSequenceId{0};
//! (memory only) Maximum nTime in the chain up to and including this block.
unsigned int nTimeMax{0};
explicit CBlockIndex(const CBlockHeader& block)
: nVersion{block.nVersion},
hashMerkleRoot{block.hashMerkleRoot},
nTime{block.nTime},
nBits{block.nBits},
nNonce{block.nNonce}
{
}
FlatFilePos GetBlockPos() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
AssertLockHeld(::cs_main);
FlatFilePos ret;
if (nStatus & BLOCK_HAVE_DATA) {
ret.nFile = nFile;
ret.nPos = nDataPos;
}
return ret;
}
FlatFilePos GetUndoPos() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
AssertLockHeld(::cs_main);
FlatFilePos ret;
if (nStatus & BLOCK_HAVE_UNDO) {
ret.nFile = nFile;
ret.nPos = nUndoPos;
}
return ret;
}
CBlockHeader GetBlockHeader() const
{
CBlockHeader block;
block.nVersion = nVersion;
if (pprev)
block.hashPrevBlock = pprev->GetBlockHash();
block.hashMerkleRoot = hashMerkleRoot;
block.nTime = nTime;
block.nBits = nBits;
block.nNonce = nNonce;
return block;
}
uint256 GetBlockHash() const
{
assert(phashBlock != nullptr);
return *phashBlock;
}
/**
* Check whether this block and all previous blocks back to the genesis block or an assumeutxo snapshot block have
* reached VALID_TRANSACTIONS and had transactions downloaded (and stored to disk) at some point.
*
* Does not imply the transactions are consensus-valid (ConnectTip might fail)
* Does not imply the transactions are still stored on disk. (IsBlockPruned might return true)
*
* Note that this will be true for the snapshot base block, if one is loaded, since its nChainTx value will have
* been set manually based on the related AssumeutxoData entry.
*/
bool HaveNumChainTxs() const { return nChainTx != 0; }
NodeSeconds Time() const
{
return NodeSeconds{std::chrono::seconds{nTime}};
}
int64_t GetBlockTime() const
{
return (int64_t)nTime;
}
int64_t GetBlockTimeMax() const
{
return (int64_t)nTimeMax;
}
static constexpr int nMedianTimeSpan = 11;
int64_t GetMedianTimePast() const
{
int64_t pmedian[nMedianTimeSpan];
int64_t* pbegin = &pmedian[nMedianTimeSpan];
int64_t* pend = &pmedian[nMedianTimeSpan];
const CBlockIndex* pindex = this;
for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
*(--pbegin) = pindex->GetBlockTime();
std::sort(pbegin, pend);
return pbegin[(pend - pbegin) / 2];
}
std::string ToString() const;
//! Check whether this block index entry is valid up to the passed validity level.
bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
AssertLockHeld(::cs_main);
assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
if (nStatus & BLOCK_FAILED_MASK)
return false;
return ((nStatus & BLOCK_VALID_MASK) >= nUpTo);
}
//! @returns true if the block is assumed-valid; this means it is queued to be
//! validated by a background chainstate.
bool IsAssumedValid() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
AssertLockHeld(::cs_main);
return nStatus & BLOCK_ASSUMED_VALID;
}
//! Raise the validity level of this block index entry.
//! Returns true if the validity was changed.
bool RaiseValidity(enum BlockStatus nUpTo) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
AssertLockHeld(::cs_main);
assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
if (nStatus & BLOCK_FAILED_MASK) return false;
if ((nStatus & BLOCK_VALID_MASK) < nUpTo) {
// If this block had been marked assumed-valid and we're raising
// its validity to a certain point, there is no longer an assumption.
if (nStatus & BLOCK_ASSUMED_VALID && nUpTo >= BLOCK_VALID_SCRIPTS) {
nStatus &= ~BLOCK_ASSUMED_VALID;
}
nStatus = (nStatus & ~BLOCK_VALID_MASK) | nUpTo;
return true;
}
return false;
}
//! Build the skiplist pointer for this entry.
void BuildSkip();
//! Efficiently find an ancestor of this block.
CBlockIndex* GetAncestor(int height);
const CBlockIndex* GetAncestor(int height) const;
CBlockIndex() = default;
~CBlockIndex() = default;
protected:
//! CBlockIndex should not allow public copy construction because equality
//! comparison via pointer is very common throughout the codebase, making
//! use of copy a footgun. Also, use of copies do not have the benefit
//! of simplifying lifetime considerations due to attributes like pprev and
//! pskip, which are at risk of becoming dangling pointers in a copied
//! instance.
//!
//! We declare these protected instead of simply deleting them so that
//! CDiskBlockIndex can reuse copy construction.
CBlockIndex(const CBlockIndex&) = default;
CBlockIndex& operator=(const CBlockIndex&) = delete;
CBlockIndex(CBlockIndex&&) = delete;
CBlockIndex& operator=(CBlockIndex&&) = delete;
};
arith_uint256 GetBlockProof(const CBlockIndex& block);
/** Return the time it would take to redo the work difference between from and to, assuming the current hashrate corresponds to the difficulty at tip, in seconds. */
int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params&);
/** Find the forking point between two chain tips. */
const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb);
/** Used to marshal pointers into hashes for db storage. */
class CDiskBlockIndex : public CBlockIndex
{
/** Historically CBlockLocator's version field has been written to disk
* streams as the client version, but the value has never been used.
*
* Hard-code to the highest client version ever written.
* SerParams can be used if the field requires any meaning in the future.
**/
static constexpr int DUMMY_VERSION = 259900;
public:
uint256 hashPrev;
CDiskBlockIndex()
{
hashPrev = uint256();
}
explicit CDiskBlockIndex(const CBlockIndex* pindex) : CBlockIndex(*pindex)
{
hashPrev = (pprev ? pprev->GetBlockHash() : uint256());
}
SERIALIZE_METHODS(CDiskBlockIndex, obj)
{
LOCK(::cs_main);
int _nVersion = DUMMY_VERSION;
READWRITE(VARINT_MODE(_nVersion, VarIntMode::NONNEGATIVE_SIGNED));
READWRITE(VARINT_MODE(obj.nHeight, VarIntMode::NONNEGATIVE_SIGNED));
READWRITE(VARINT(obj.nStatus));
READWRITE(VARINT(obj.nTx));
if (obj.nStatus & (BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO)) READWRITE(VARINT_MODE(obj.nFile, VarIntMode::NONNEGATIVE_SIGNED));
if (obj.nStatus & BLOCK_HAVE_DATA) READWRITE(VARINT(obj.nDataPos));
if (obj.nStatus & BLOCK_HAVE_UNDO) READWRITE(VARINT(obj.nUndoPos));
// block header
READWRITE(obj.nVersion);
READWRITE(obj.hashPrev);
READWRITE(obj.hashMerkleRoot);
READWRITE(obj.nTime);
READWRITE(obj.nBits);
READWRITE(obj.nNonce);
}
uint256 ConstructBlockHash() const
{
CBlockHeader block;
block.nVersion = nVersion;
block.hashPrevBlock = hashPrev;
block.hashMerkleRoot = hashMerkleRoot;
block.nTime = nTime;
block.nBits = nBits;
block.nNonce = nNonce;
return block.GetHash();
}
uint256 GetBlockHash() = delete;
std::string ToString() = delete;
};
/** An in-memory indexed chain of blocks. */
class CChain
{
private:
std::vector<CBlockIndex*> vChain;
public:
CChain() = default;
CChain(const CChain&) = delete;
CChain& operator=(const CChain&) = delete;
/** Returns the index entry for the genesis block of this chain, or nullptr if none. */
CBlockIndex* Genesis() const
{
return vChain.size() > 0 ? vChain[0] : nullptr;
}
/** Returns the index entry for the tip of this chain, or nullptr if none. */
CBlockIndex* Tip() const
{
return vChain.size() > 0 ? vChain[vChain.size() - 1] : nullptr;
}
/** Returns the index entry at a particular height in this chain, or nullptr if no such height exists. */
CBlockIndex* operator[](int nHeight) const
{
if (nHeight < 0 || nHeight >= (int)vChain.size())
return nullptr;
return vChain[nHeight];
}
/** Efficiently check whether a block is present in this chain. */
bool Contains(const CBlockIndex* pindex) const
{
return (*this)[pindex->nHeight] == pindex;
}
/** Find the successor of a block in this chain, or nullptr if the given index is not found or is the tip. */
CBlockIndex* Next(const CBlockIndex* pindex) const
{
if (Contains(pindex))
return (*this)[pindex->nHeight + 1];
else
return nullptr;
}
/** Return the maximal height in the chain. Is equal to chain.Tip() ? chain.Tip()->nHeight : -1. */
int Height() const
{
return int(vChain.size()) - 1;
}
/** Set/initialize a chain with a given tip. */
void SetTip(CBlockIndex& block);
/** Return a CBlockLocator that refers to the tip in of this chain. */
CBlockLocator GetLocator() const;
/** Find the last common block between this chain and a block index entry. */
const CBlockIndex* FindFork(const CBlockIndex* pindex) const;
/** Find the earliest block with timestamp equal or greater than the given time and height equal or greater than the given height. */
CBlockIndex* FindEarliestAtLeast(int64_t nTime, int height) const;
};
/** Get a locator for a block index entry. */
CBlockLocator GetLocator(const CBlockIndex* index);
/** Construct a list of hash entries to put in a locator. */
std::vector<uint256> LocatorEntries(const CBlockIndex* index);
#endif // BITCOIN_CHAIN_H
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