src/chain.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2014 The Bitcoin Core developers
   3 // Distributed under the MIT software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #ifndef BITCOIN_CHAIN_H
   7 #define BITCOIN_CHAIN_H
   8
   9 #include "arith_uint256.h"
  10 #include "primitives/block.h"
  11 #include "pow.h"
  12 #include "tinyformat.h"
  13 #include "uint256.h"
  14
  15 #include <vector>
  16
  17 #include <boost/foreach.hpp>
  18
  19 struct CDiskBlockPos
  20 {
  21     int nFile;
  22     unsigned int nPos;
  23
  24     ADD_SERIALIZE_METHODS;
  25
  26     template <typename Stream, typename Operation>
  27     inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
  28         READWRITE(VARINT(nFile));
  29         READWRITE(VARINT(nPos));
  30     }
  31
  32     CDiskBlockPos() {
  33         SetNull();
  34     }
  35
  36     CDiskBlockPos(int nFileIn, unsigned int nPosIn) {
  37         nFile = nFileIn;
  38         nPos = nPosIn;
  39     }
  40
  41     friend bool operator==(const CDiskBlockPos &a, const CDiskBlockPos &b) {
  42         return (a.nFile == b.nFile && a.nPos == b.nPos);
  43     }
  44
  45     friend bool operator!=(const CDiskBlockPos &a, const CDiskBlockPos &b) {
  46         return !(a == b);
  47     }
  48
  49     void SetNull() { nFile = -1; nPos = 0; }
  50     bool IsNull() const { return (nFile == -1); }
  51
  52     std::string ToString() const
  53     {
  54         return strprintf("CBlockDiskPos(nFile=%i, nPos=%i)", nFile, nPos);
  55     }
  56
  57 };
  58
  59 enum BlockStatus {
  60     //! Unused.
  61     BLOCK_VALID_UNKNOWN      =    0,
  62
  63     //! Parsed, version ok, hash satisfies claimed PoW, 1 <= vtx count <= max, timestamp not in future
  64     BLOCK_VALID_HEADER       =    1,
  65
  66     //! All parent headers found, difficulty matches, timestamp >= median previous, checkpoint. Implies all parents
  67     //! are also at least TREE.
  68     BLOCK_VALID_TREE         =    2,
  69
  70     /**
  71      * Only first tx is coinbase, 2 <= coinbase input script length <= 100, transactions valid, no duplicate txids,
  72      * sigops, size, merkle root. Implies all parents are at least TREE but not necessarily TRANSACTIONS. When all
  73      * parent blocks also have TRANSACTIONS, CBlockIndex::nChainTx will be set.
  74      */
  75     BLOCK_VALID_TRANSACTIONS =    3,
  76
  77     //! Outputs do not overspend inputs, no double spends, coinbase output ok, no immature coinbase spends, BIP30.
  78     //! Implies all parents are also at least CHAIN.
  79     BLOCK_VALID_CHAIN        =    4,
  80
  81     //! Scripts & signatures ok. Implies all parents are also at least SCRIPTS.
  82     BLOCK_VALID_SCRIPTS      =    5,
  83
  84     //! All validity bits.
  85     BLOCK_VALID_MASK         =   BLOCK_VALID_HEADER | BLOCK_VALID_TREE | BLOCK_VALID_TRANSACTIONS |
  86                                  BLOCK_VALID_CHAIN | BLOCK_VALID_SCRIPTS,
  87
  88     BLOCK_HAVE_DATA          =    8, //! full block available in blk*.dat
  89     BLOCK_HAVE_UNDO          =   16, //! undo data available in rev*.dat
  90     BLOCK_HAVE_MASK          =   BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
  91
  92     BLOCK_FAILED_VALID       =   32, //! stage after last reached validness failed
  93     BLOCK_FAILED_CHILD       =   64, //! descends from failed block
  94     BLOCK_FAILED_MASK        =   BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
  95 };
  96
  97 /** The block chain is a tree shaped structure starting with the
  98  * genesis block at the root, with each block potentially having multiple
  99  * candidates to be the next block. A blockindex may have multiple pprev pointing
 100  * to it, but at most one of them can be part of the currently active branch.
 101  */
 102 class CBlockIndex
 103 {
 104 public:
 105     //! pointer to the hash of the block, if any. Memory is owned by this CBlockIndex
 106     const uint256* phashBlock;
 107
 108     //! pointer to the index of the predecessor of this block
 109     CBlockIndex* pprev;
 110
 111     //! pointer to the index of some further predecessor of this block
 112     CBlockIndex* pskip;
 113
 114     //! height of the entry in the chain. The genesis block has height 0
 115     int nHeight;
 116
 117     //! Which # file this block is stored in (blk?????.dat)
 118     int nFile;
 119
 120     //! Byte offset within blk?????.dat where this block's data is stored
 121     unsigned int nDataPos;
 122
 123     //! Byte offset within rev?????.dat where this block's undo data is stored
 124     unsigned int nUndoPos;
 125
 126     //! (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
 127     arith_uint256 nChainWork;
 128
 129     //! Number of transactions in this block.
 130     //! Note: in a potential headers-first mode, this number cannot be relied upon
 131     unsigned int nTx;
 132
 133     //! (memory only) Number of transactions in the chain up to and including this block.
 134     //! This value will be non-zero only if and only if transactions for this block and all its parents are available.
 135     //! Change to 64-bit type when necessary; won't happen before 2030
 136     unsigned int nChainTx;
 137
 138     //! Verification status of this block. See enum BlockStatus
 139     unsigned int nStatus;
 140
 141     //! block header
 142     int nVersion;
 143     uint256 hashMerkleRoot;
 144     unsigned int nTime;
 145     unsigned int nBits;
 146     unsigned int nNonce;
 147
 148     //! (memory only) Sequential id assigned to distinguish order in which blocks are received.
 149     uint32_t nSequenceId;
 150
 151     void SetNull()
 152     {
 153         phashBlock = NULL;
 154         pprev = NULL;
 155         pskip = NULL;
 156         nHeight = 0;
 157         nFile = 0;
 158         nDataPos = 0;
 159         nUndoPos = 0;
 160         nChainWork = arith_uint256();
 161         nTx = 0;
 162         nChainTx = 0;
 163         nStatus = 0;
 164         nSequenceId = 0;
 165
 166         nVersion       = 0;
 167         hashMerkleRoot = uint256();
 168         nTime          = 0;
 169         nBits          = 0;
 170         nNonce         = 0;
 171     }
 172
 173     CBlockIndex()
 174     {
 175         SetNull();
 176     }
 177
 178     CBlockIndex(const CBlockHeader& block)
 179     {
 180         SetNull();
 181
 182         nVersion       = block.nVersion;
 183         hashMerkleRoot = block.hashMerkleRoot;
 184         nTime          = block.nTime;
 185         nBits          = block.nBits;
 186         nNonce         = block.nNonce;
 187     }
 188
 189     CDiskBlockPos GetBlockPos() const {
 190         CDiskBlockPos ret;
 191         if (nStatus & BLOCK_HAVE_DATA) {
 192             ret.nFile = nFile;
 193             ret.nPos  = nDataPos;
 194         }
 195         return ret;
 196     }
 197
 198     CDiskBlockPos GetUndoPos() const {
 199         CDiskBlockPos ret;
 200         if (nStatus & BLOCK_HAVE_UNDO) {
 201             ret.nFile = nFile;
 202             ret.nPos  = nUndoPos;
 203         }
 204         return ret;
 205     }
 206
 207     CBlockHeader GetBlockHeader() const
 208     {
 209         CBlockHeader block;
 210         block.nVersion       = nVersion;
 211         if (pprev)
 212             block.hashPrevBlock = pprev->GetBlockHash();
 213         block.hashMerkleRoot = hashMerkleRoot;
 214         block.nTime          = nTime;
 215         block.nBits          = nBits;
 216         block.nNonce         = nNonce;
 217         return block;
 218     }
 219
 220     uint256 GetBlockHash() const
 221     {
 222         return *phashBlock;
 223     }
 224
 225     int64_t GetBlockTime() const
 226     {
 227         return (int64_t)nTime;
 228     }
 229
 230     enum { nMedianTimeSpan=11 };
 231
 232     int64_t GetMedianTimePast() const
 233     {
 234         int64_t pmedian[nMedianTimeSpan];
 235         int64_t* pbegin = &pmedian[nMedianTimeSpan];
 236         int64_t* pend = &pmedian[nMedianTimeSpan];
 237
 238         const CBlockIndex* pindex = this;
 239         for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
 240             *(--pbegin) = pindex->GetBlockTime();
 241
 242         std::sort(pbegin, pend);
 243         return pbegin[(pend - pbegin)/2];
 244     }
 245
 246     std::string ToString() const
 247     {
 248         return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
 249             pprev, nHeight,
 250             hashMerkleRoot.ToString(),
 251             GetBlockHash().ToString());
 252     }
 253
 254     //! Check whether this block index entry is valid up to the passed validity level.
 255     bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
 256     {
 257         assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
 258         if (nStatus & BLOCK_FAILED_MASK)
 259             return false;
 260         return ((nStatus & BLOCK_VALID_MASK) >= nUpTo);
 261     }
 262
 263     //! Raise the validity level of this block index entry.
 264     //! Returns true if the validity was changed.
 265     bool RaiseValidity(enum BlockStatus nUpTo)
 266     {
 267         assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
 268         if (nStatus & BLOCK_FAILED_MASK)
 269             return false;
 270         if ((nStatus & BLOCK_VALID_MASK) < nUpTo) {
 271             nStatus = (nStatus & ~BLOCK_VALID_MASK) | nUpTo;
 272             return true;
 273         }
 274         return false;
 275     }
 276
 277     //! Build the skiplist pointer for this entry.
 278     void BuildSkip();
 279
 280     //! Efficiently find an ancestor of this block.
 281     CBlockIndex* GetAncestor(int height);
 282     const CBlockIndex* GetAncestor(int height) const;
 283 };
 284
 285 /** Used to marshal pointers into hashes for db storage. */
 286 class CDiskBlockIndex : public CBlockIndex
 287 {
 288 public:
 289     uint256 hashPrev;
 290
 291     CDiskBlockIndex() {
 292         hashPrev = uint256();
 293     }
 294
 295     explicit CDiskBlockIndex(const CBlockIndex* pindex) : CBlockIndex(*pindex) {
 296         hashPrev = (pprev ? pprev->GetBlockHash() : uint256());
 297     }
 298
 299     ADD_SERIALIZE_METHODS;
 300
 301     template <typename Stream, typename Operation>
 302     inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
 303         if (!(nType & SER_GETHASH))
 304             READWRITE(VARINT(nVersion));
 305
 306         READWRITE(VARINT(nHeight));
 307         READWRITE(VARINT(nStatus));
 308         READWRITE(VARINT(nTx));
 309         if (nStatus & (BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO))
 310             READWRITE(VARINT(nFile));
 311         if (nStatus & BLOCK_HAVE_DATA)
 312             READWRITE(VARINT(nDataPos));
 313         if (nStatus & BLOCK_HAVE_UNDO)
 314             READWRITE(VARINT(nUndoPos));
 315
 316         // block header
 317         READWRITE(this->nVersion);
 318         READWRITE(hashPrev);
 319         READWRITE(hashMerkleRoot);
 320         READWRITE(nTime);
 321         READWRITE(nBits);
 322         READWRITE(nNonce);
 323     }
 324
 325     uint256 GetBlockHash() const
 326     {
 327         CBlockHeader block;
 328         block.nVersion        = nVersion;
 329         block.hashPrevBlock   = hashPrev;
 330         block.hashMerkleRoot  = hashMerkleRoot;
 331         block.nTime           = nTime;
 332         block.nBits           = nBits;
 333         block.nNonce          = nNonce;
 334         return block.GetHash();
 335     }
 336
 337
 338     std::string ToString() const
 339     {
 340         std::string str = "CDiskBlockIndex(";
 341         str += CBlockIndex::ToString();
 342         str += strprintf("\n                hashBlock=%s, hashPrev=%s)",
 343             GetBlockHash().ToString(),
 344             hashPrev.ToString());
 345         return str;
 346     }
 347 };
 348
 349 /** An in-memory indexed chain of blocks. */
 350 class CChain {
 351 private:
 352     std::vector<CBlockIndex*> vChain;
 353
 354 public:
 355     /** Returns the index entry for the genesis block of this chain, or NULL if none. */
 356     CBlockIndex *Genesis() const {
 357         return vChain.size() > 0 ? vChain[0] : NULL;
 358     }
 359
 360     /** Returns the index entry for the tip of this chain, or NULL if none. */
 361     CBlockIndex *Tip() const {
 362         return vChain.size() > 0 ? vChain[vChain.size() - 1] : NULL;
 363     }
 364
 365     /** Returns the index entry at a particular height in this chain, or NULL if no such height exists. */
 366     CBlockIndex *operator[](int nHeight) const {
 367         if (nHeight < 0 || nHeight >= (int)vChain.size())
 368             return NULL;
 369         return vChain[nHeight];
 370     }
 371
 372     /** Compare two chains efficiently. */
 373     friend bool operator==(const CChain &a, const CChain &b) {
 374         return a.vChain.size() == b.vChain.size() &&
 375                a.vChain[a.vChain.size() - 1] == b.vChain[b.vChain.size() - 1];
 376     }
 377
 378     /** Efficiently check whether a block is present in this chain. */
 379     bool Contains(const CBlockIndex *pindex) const {
 380         return (*this)[pindex->nHeight] == pindex;
 381     }
 382
 383     /** Find the successor of a block in this chain, or NULL if the given index is not found or is the tip. */
 384     CBlockIndex *Next(const CBlockIndex *pindex) const {
 385         if (Contains(pindex))
 386             return (*this)[pindex->nHeight + 1];
 387         else
 388             return NULL;
 389     }
 390
 391     /** Return the maximal height in the chain. Is equal to chain.Tip() ? chain.Tip()->nHeight : -1. */
 392     int Height() const {
 393         return vChain.size() - 1;
 394     }
 395
 396     /** Set/initialize a chain with a given tip. */
 397     void SetTip(CBlockIndex *pindex);
 398
 399     /** Return a CBlockLocator that refers to a block in this chain (by default the tip). */
 400     CBlockLocator GetLocator(const CBlockIndex *pindex = NULL) const;
 401
 402     /** Find the last common block between this chain and a block index entry. */
 403     const CBlockIndex *FindFork(const CBlockIndex *pindex) const;
 404 };
 405
 406 #endif // BITCOIN_CHAIN_H