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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 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 <consensus/params.h>
11 : : #include <flatfile.h>
12 : : #include <kernel/cs_main.h>
13 : : #include <primitives/block.h>
14 : : #include <serialize.h>
15 : : #include <sync.h>
16 : : #include <uint256.h>
17 : : #include <util/time.h>
18 : :
19 : : #include <algorithm>
20 : : #include <cassert>
21 : : #include <cstdint>
22 : : #include <string>
23 : : #include <vector>
24 : :
25 : : /**
26 : : * Maximum amount of time that a block timestamp is allowed to exceed the
27 : : * current time before the block will be accepted.
28 : : */
29 : : static constexpr int64_t MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60;
30 : :
31 : : /**
32 : : * Timestamp window used as a grace period by code that compares external
33 : : * timestamps (such as timestamps passed to RPCs, or wallet key creation times)
34 : : * to block timestamps. This should be set at least as high as
35 : : * MAX_FUTURE_BLOCK_TIME.
36 : : */
37 : : static constexpr int64_t TIMESTAMP_WINDOW = MAX_FUTURE_BLOCK_TIME;
38 : :
39 : : /**
40 : : * Maximum gap between node time and block time used
41 : : * for the "Catching up..." mode in GUI.
42 : : *
43 : : * Ref: https://github.com/bitcoin/bitcoin/pull/1026
44 : : */
45 : : static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
46 : :
47 : : class CBlockFileInfo
48 : : {
49 : : public:
50 : 4176 : unsigned int nBlocks{}; //!< number of blocks stored in file
51 : 4176 : unsigned int nSize{}; //!< number of used bytes of block file
52 : 4176 : unsigned int nUndoSize{}; //!< number of used bytes in the undo file
53 : 4176 : unsigned int nHeightFirst{}; //!< lowest height of block in file
54 : 4176 : unsigned int nHeightLast{}; //!< highest height of block in file
55 : 4176 : uint64_t nTimeFirst{}; //!< earliest time of block in file
56 : 4176 : uint64_t nTimeLast{}; //!< latest time of block in file
57 : :
58 : 278073 : SERIALIZE_METHODS(CBlockFileInfo, obj)
59 : : {
60 : 92691 : READWRITE(VARINT(obj.nBlocks));
61 : 92691 : READWRITE(VARINT(obj.nSize));
62 : 92691 : READWRITE(VARINT(obj.nUndoSize));
63 : 92691 : READWRITE(VARINT(obj.nHeightFirst));
64 : 92691 : READWRITE(VARINT(obj.nHeightLast));
65 : 92691 : READWRITE(VARINT(obj.nTimeFirst));
66 : 92691 : READWRITE(VARINT(obj.nTimeLast));
67 : 92691 : }
68 : :
69 : 8352 : CBlockFileInfo() {}
70 : :
71 : : std::string ToString() const;
72 : :
73 : : /** update statistics (does not update nSize) */
74 : 92838 : void AddBlock(unsigned int nHeightIn, uint64_t nTimeIn)
75 : : {
76 [ + + - + ]: 92838 : if (nBlocks == 0 || nHeightFirst > nHeightIn)
77 : 2055 : nHeightFirst = nHeightIn;
78 [ + + - + ]: 92838 : if (nBlocks == 0 || nTimeFirst > nTimeIn)
79 : 2055 : nTimeFirst = nTimeIn;
80 : 92838 : nBlocks++;
81 [ + + ]: 92838 : if (nHeightIn > nHeightLast)
82 : 83604 : nHeightLast = nHeightIn;
83 [ + + ]: 92838 : if (nTimeIn > nTimeLast)
84 : 18516 : nTimeLast = nTimeIn;
85 : 92838 : }
86 : : };
87 : :
88 : : enum BlockStatus : uint32_t {
89 : : //! Unused.
90 : : BLOCK_VALID_UNKNOWN = 0,
91 : :
92 : : //! Reserved (was BLOCK_VALID_HEADER).
93 : : BLOCK_VALID_RESERVED = 1,
94 : :
95 : : //! All parent headers found, difficulty matches, timestamp >= median previous, checkpoint. Implies all parents
96 : : //! are also at least TREE.
97 : : BLOCK_VALID_TREE = 2,
98 : :
99 : : /**
100 : : * Only first tx is coinbase, 2 <= coinbase input script length <= 100, transactions valid, no duplicate txids,
101 : : * sigops, size, merkle root. Implies all parents are at least TREE but not necessarily TRANSACTIONS.
102 : : *
103 : : * If a block's validity is at least VALID_TRANSACTIONS, CBlockIndex::nTx will be set. If a block and all previous
104 : : * blocks back to the genesis block or an assumeutxo snapshot block are at least VALID_TRANSACTIONS,
105 : : * CBlockIndex::nChainTx will be set.
106 : : */
107 : : BLOCK_VALID_TRANSACTIONS = 3,
108 : :
109 : : //! Outputs do not overspend inputs, no double spends, coinbase output ok, no immature coinbase spends, BIP30.
110 : : //! Implies all previous blocks back to the genesis block or an assumeutxo snapshot block are at least VALID_CHAIN.
111 : : BLOCK_VALID_CHAIN = 4,
112 : :
113 : : //! Scripts & signatures ok. Implies all previous blocks back to the genesis block or an assumeutxo snapshot block
114 : : //! are at least VALID_SCRIPTS.
115 : : BLOCK_VALID_SCRIPTS = 5,
116 : :
117 : : //! All validity bits.
118 : : BLOCK_VALID_MASK = BLOCK_VALID_RESERVED | BLOCK_VALID_TREE | BLOCK_VALID_TRANSACTIONS |
119 : : BLOCK_VALID_CHAIN | BLOCK_VALID_SCRIPTS,
120 : :
121 : : BLOCK_HAVE_DATA = 8, //!< full block available in blk*.dat
122 : : BLOCK_HAVE_UNDO = 16, //!< undo data available in rev*.dat
123 : : BLOCK_HAVE_MASK = BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
124 : :
125 : : BLOCK_FAILED_VALID = 32, //!< stage after last reached validness failed
126 : : BLOCK_FAILED_CHILD = 64, //!< descends from failed block
127 : : BLOCK_FAILED_MASK = BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
128 : :
129 : : BLOCK_OPT_WITNESS = 128, //!< block data in blk*.dat was received with a witness-enforcing client
130 : :
131 : : BLOCK_STATUS_RESERVED = 256, //!< Unused flag that was previously set on assumeutxo snapshot blocks and their
132 : : //!< ancestors before they were validated, and unset when they were validated.
133 : : };
134 : :
135 : : /** The block chain is a tree shaped structure starting with the
136 : : * genesis block at the root, with each block potentially having multiple
137 : : * candidates to be the next block. A blockindex may have multiple pprev pointing
138 : : * to it, but at most one of them can be part of the currently active branch.
139 : : */
140 : : class CBlockIndex
141 : : {
142 : : public:
143 : : //! pointer to the hash of the block, if any. Memory is owned by this CBlockIndex
144 : 1725384 : const uint256* phashBlock{nullptr};
145 : :
146 : : //! pointer to the index of the predecessor of this block
147 : 1725384 : CBlockIndex* pprev{nullptr};
148 : :
149 : : //! pointer to the index of some further predecessor of this block
150 : 1725384 : CBlockIndex* pskip{nullptr};
151 : :
152 : : //! height of the entry in the chain. The genesis block has height 0
153 : 1725384 : int nHeight{0};
154 : :
155 : : //! Which # file this block is stored in (blk?????.dat)
156 : 1725384 : int nFile GUARDED_BY(::cs_main){0};
157 : :
158 : : //! Byte offset within blk?????.dat where this block's data is stored
159 : 1725384 : unsigned int nDataPos GUARDED_BY(::cs_main){0};
160 : :
161 : : //! Byte offset within rev?????.dat where this block's undo data is stored
162 : 1725384 : unsigned int nUndoPos GUARDED_BY(::cs_main){0};
163 : :
164 : : //! (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
165 : 1725384 : arith_uint256 nChainWork{};
166 : :
167 : : //! Number of transactions in this block. This will be nonzero if the block
168 : : //! reached the VALID_TRANSACTIONS level, and zero otherwise.
169 : : //! Note: in a potential headers-first mode, this number cannot be relied upon
170 : 1725384 : unsigned int nTx{0};
171 : :
172 : : //! (memory only) Number of transactions in the chain up to and including this block.
173 : : //! This value will be non-zero if this block and all previous blocks back
174 : : //! to the genesis block or an assumeutxo snapshot block have reached the
175 : : //! VALID_TRANSACTIONS level.
176 : : //! Change to 64-bit type before 2024 (assuming worst case of 60 byte transactions).
177 : 1725384 : unsigned int nChainTx{0};
178 : :
179 : : //! Verification status of this block. See enum BlockStatus
180 : : //!
181 : : //! Note: this value is modified to show BLOCK_OPT_WITNESS during UTXO snapshot
182 : : //! load to avoid the block index being spuriously rewound.
183 : : //! @sa NeedsRedownload
184 : : //! @sa ActivateSnapshot
185 : 1725384 : uint32_t nStatus GUARDED_BY(::cs_main){0};
186 : :
187 : : //! block header
188 : 468244 : int32_t nVersion{0};
189 : 468244 : uint256 hashMerkleRoot{};
190 : 468244 : uint32_t nTime{0};
191 : 468244 : uint32_t nBits{0};
192 : 468244 : uint32_t nNonce{0};
193 : :
194 : : //! (memory only) Sequential id assigned to distinguish order in which blocks are received.
195 : 1725384 : int32_t nSequenceId{0};
196 : :
197 : : //! (memory only) Maximum nTime in the chain up to and including this block.
198 : 1725384 : unsigned int nTimeMax{0};
199 : :
200 : 1257140 : explicit CBlockIndex(const CBlockHeader& block)
201 : 1257140 : : nVersion{block.nVersion},
202 : 1257140 : hashMerkleRoot{block.hashMerkleRoot},
203 : 1257140 : nTime{block.nTime},
204 : 1257140 : nBits{block.nBits},
205 : 1257140 : nNonce{block.nNonce}
206 : : {
207 : 1257140 : }
208 : :
209 : 5179 : FlatFilePos GetBlockPos() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
210 : : {
211 : 5179 : AssertLockHeld(::cs_main);
212 : 5179 : FlatFilePos ret;
213 [ + + ]: 5179 : if (nStatus & BLOCK_HAVE_DATA) {
214 : 5102 : ret.nFile = nFile;
215 : 5102 : ret.nPos = nDataPos;
216 : 5102 : }
217 : 5179 : return ret;
218 : : }
219 : :
220 : 83263 : FlatFilePos GetUndoPos() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
221 : : {
222 : 83263 : AssertLockHeld(::cs_main);
223 : 83263 : FlatFilePos ret;
224 [ + + ]: 83263 : if (nStatus & BLOCK_HAVE_UNDO) {
225 : 11 : ret.nFile = nFile;
226 : 11 : ret.nPos = nUndoPos;
227 : 11 : }
228 : 83263 : return ret;
229 : : }
230 : :
231 : 160241 : CBlockHeader GetBlockHeader() const
232 : : {
233 : 160241 : CBlockHeader block;
234 : 160241 : block.nVersion = nVersion;
235 [ + + ]: 160241 : if (pprev)
236 : 159785 : block.hashPrevBlock = pprev->GetBlockHash();
237 : 160241 : block.hashMerkleRoot = hashMerkleRoot;
238 : 160241 : block.nTime = nTime;
239 : 160241 : block.nBits = nBits;
240 : 160241 : block.nNonce = nNonce;
241 : 160241 : return block;
242 : : }
243 : :
244 : 5086547 : uint256 GetBlockHash() const
245 : : {
246 [ + - ]: 5086547 : assert(phashBlock != nullptr);
247 : 5086547 : return *phashBlock;
248 : : }
249 : :
250 : : /**
251 : : * Check whether this block and all previous blocks back to the genesis block or an assumeutxo snapshot block have
252 : : * reached VALID_TRANSACTIONS and had transactions downloaded (and stored to disk) at some point.
253 : : *
254 : : * Does not imply the transactions are consensus-valid (ConnectTip might fail)
255 : : * Does not imply the transactions are still stored on disk. (IsBlockPruned might return true)
256 : : *
257 : : * Note that this will be true for the snapshot base block, if one is loaded, since its nChainTx value will have
258 : : * been set manually based on the related AssumeutxoData entry.
259 : : */
260 : 187944817 : bool HaveNumChainTxs() const { return nChainTx != 0; }
261 : :
262 : 1637417 : NodeSeconds Time() const
263 : : {
264 : 1637417 : return NodeSeconds{std::chrono::seconds{nTime}};
265 : : }
266 : :
267 : 22287728 : int64_t GetBlockTime() const
268 : : {
269 : 22287728 : return (int64_t)nTime;
270 : : }
271 : :
272 : 83 : int64_t GetBlockTimeMax() const
273 : : {
274 : 83 : return (int64_t)nTimeMax;
275 : : }
276 : :
277 : : static constexpr int nMedianTimeSpan = 11;
278 : :
279 : 2039035 : int64_t GetMedianTimePast() const
280 : : {
281 : 2039035 : int64_t pmedian[nMedianTimeSpan];
282 : 2039035 : int64_t* pbegin = &pmedian[nMedianTimeSpan];
283 : 2039035 : int64_t* pend = &pmedian[nMedianTimeSpan];
284 : :
285 : 2039035 : const CBlockIndex* pindex = this;
286 [ + + + + ]: 23291168 : for (int i = 0; i < nMedianTimeSpan && pindex; i++, pindex = pindex->pprev)
287 : 21252133 : *(--pbegin) = pindex->GetBlockTime();
288 : :
289 : 2039035 : std::sort(pbegin, pend);
290 : 4078070 : return pbegin[(pend - pbegin) / 2];
291 : 2039035 : }
292 : :
293 : : std::string ToString() const;
294 : :
295 : : //! Check whether this block index entry is valid up to the passed validity level.
296 : 336745 : bool IsValid(enum BlockStatus nUpTo = BLOCK_VALID_TRANSACTIONS) const
297 : : EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
298 : : {
299 : 336745 : AssertLockHeld(::cs_main);
300 [ + - ]: 336745 : assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
301 [ + + ]: 336745 : if (nStatus & BLOCK_FAILED_MASK)
302 : 30 : return false;
303 : 336715 : return ((nStatus & BLOCK_VALID_MASK) >= nUpTo);
304 : 336745 : }
305 : :
306 : : //! Raise the validity level of this block index entry.
307 : : //! Returns true if the validity was changed.
308 : 417886 : bool RaiseValidity(enum BlockStatus nUpTo) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
309 : : {
310 : 417886 : AssertLockHeld(::cs_main);
311 [ + - ]: 417886 : assert(!(nUpTo & ~BLOCK_VALID_MASK)); // Only validity flags allowed.
312 [ + + ]: 417886 : if (nStatus & BLOCK_FAILED_MASK) return false;
313 : :
314 [ + + ]: 416765 : if ((nStatus & BLOCK_VALID_MASK) < nUpTo) {
315 : 415184 : nStatus = (nStatus & ~BLOCK_VALID_MASK) | nUpTo;
316 : 415184 : return true;
317 : : }
318 : 1581 : return false;
319 : 417886 : }
320 : :
321 : : //! Build the skiplist pointer for this entry.
322 : : void BuildSkip();
323 : :
324 : : //! Efficiently find an ancestor of this block.
325 : : CBlockIndex* GetAncestor(int height);
326 : : const CBlockIndex* GetAncestor(int height) const;
327 : :
328 : 936488 : CBlockIndex() = default;
329 : : ~CBlockIndex() = default;
330 : :
331 : : protected:
332 : : //! CBlockIndex should not allow public copy construction because equality
333 : : //! comparison via pointer is very common throughout the codebase, making
334 : : //! use of copy a footgun. Also, use of copies do not have the benefit
335 : : //! of simplifying lifetime considerations due to attributes like pprev and
336 : : //! pskip, which are at risk of becoming dangling pointers in a copied
337 : : //! instance.
338 : : //!
339 : : //! We declare these protected instead of simply deleting them so that
340 : : //! CDiskBlockIndex can reuse copy construction.
341 : 208555 : CBlockIndex(const CBlockIndex&) = default;
342 : : CBlockIndex& operator=(const CBlockIndex&) = delete;
343 : : CBlockIndex(CBlockIndex&&) = delete;
344 : : CBlockIndex& operator=(CBlockIndex&&) = delete;
345 : : };
346 : :
347 : : arith_uint256 GetBlockProof(const CBlockIndex& block);
348 : : /** 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. */
349 : : int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params&);
350 : : /** Find the forking point between two chain tips. */
351 : : const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb);
352 : :
353 : :
354 : : /** Used to marshal pointers into hashes for db storage. */
355 : : class CDiskBlockIndex : public CBlockIndex
356 : : {
357 : : /** Historically CBlockLocator's version field has been written to disk
358 : : * streams as the client version, but the value has never been used.
359 : : *
360 : : * Hard-code to the highest client version ever written.
361 : : * SerParams can be used if the field requires any meaning in the future.
362 : : **/
363 : : static constexpr int DUMMY_VERSION = 259900;
364 : :
365 : : public:
366 : : uint256 hashPrev;
367 : :
368 : 190 : CDiskBlockIndex()
369 : : {
370 : 190 : hashPrev = uint256();
371 : 190 : }
372 : :
373 : 208389 : explicit CDiskBlockIndex(const CBlockIndex* pindex) : CBlockIndex(*pindex)
374 : : {
375 [ + + ]: 208389 : hashPrev = (pprev ? pprev->GetBlockHash() : uint256());
376 : 208389 : }
377 : :
378 : 625842 : SERIALIZE_METHODS(CDiskBlockIndex, obj)
379 : : {
380 : 208614 : LOCK(::cs_main);
381 : 208614 : int _nVersion = DUMMY_VERSION;
382 [ + - + + : 208614 : READWRITE(VARINT_MODE(_nVersion, VarIntMode::NONNEGATIVE_SIGNED));
+ - + - ]
383 : :
384 [ + - + + : 208600 : READWRITE(VARINT_MODE(obj.nHeight, VarIntMode::NONNEGATIVE_SIGNED));
+ - + - ]
385 [ + - + + : 208594 : READWRITE(VARINT(obj.nStatus));
+ - + - ]
386 [ + - + + : 208582 : READWRITE(VARINT(obj.nTx));
+ - + - ]
387 [ + + + - : 208574 : if (obj.nStatus & (BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO)) READWRITE(VARINT_MODE(obj.nFile, VarIntMode::NONNEGATIVE_SIGNED));
+ + + + +
- + - ]
388 [ + + + - : 208569 : if (obj.nStatus & BLOCK_HAVE_DATA) READWRITE(VARINT(obj.nDataPos));
+ + + + +
- + - ]
389 [ + + + - : 208566 : if (obj.nStatus & BLOCK_HAVE_UNDO) READWRITE(VARINT(obj.nUndoPos));
+ + + + +
- + - ]
390 : :
391 : : // block header
392 [ + + + - ]: 208556 : READWRITE(obj.nVersion);
393 [ + + + - ]: 208550 : READWRITE(obj.hashPrev);
394 [ + - + - ]: 208546 : READWRITE(obj.hashMerkleRoot);
395 [ + + + - ]: 208546 : READWRITE(obj.nTime);
396 [ + + + - ]: 208544 : READWRITE(obj.nBits);
397 [ + - + - ]: 208542 : READWRITE(obj.nNonce);
398 : 208614 : }
399 : :
400 : 83 : uint256 ConstructBlockHash() const
401 : : {
402 : 83 : CBlockHeader block;
403 : 83 : block.nVersion = nVersion;
404 : 83 : block.hashPrevBlock = hashPrev;
405 : 83 : block.hashMerkleRoot = hashMerkleRoot;
406 : 83 : block.nTime = nTime;
407 : 83 : block.nBits = nBits;
408 : 83 : block.nNonce = nNonce;
409 : 83 : return block.GetHash();
410 : 83 : }
411 : :
412 : : uint256 GetBlockHash() = delete;
413 : : std::string ToString() = delete;
414 : : };
415 : :
416 : : /** An in-memory indexed chain of blocks. */
417 : : class CChain
418 : : {
419 : : private:
420 : : std::vector<CBlockIndex*> vChain;
421 : :
422 : : public:
423 : 3313 : CChain() = default;
424 : : CChain(const CChain&) = delete;
425 : : CChain& operator=(const CChain&) = delete;
426 : :
427 : : /** Returns the index entry for the genesis block of this chain, or nullptr if none. */
428 : 1029629 : CBlockIndex* Genesis() const
429 : : {
430 [ + - ]: 1029629 : return vChain.size() > 0 ? vChain[0] : nullptr;
431 : : }
432 : :
433 : : /** Returns the index entry for the tip of this chain, or nullptr if none. */
434 : 133757888 : CBlockIndex* Tip() const
435 : : {
436 [ + + ]: 133757888 : return vChain.size() > 0 ? vChain[vChain.size() - 1] : nullptr;
437 : : }
438 : :
439 : : /** Returns the index entry at a particular height in this chain, or nullptr if no such height exists. */
440 : 847156 : CBlockIndex* operator[](int nHeight) const
441 : : {
442 [ + - + + ]: 847156 : if (nHeight < 0 || nHeight >= (int)vChain.size())
443 : 106439 : return nullptr;
444 : 740717 : return vChain[nHeight];
445 : 847156 : }
446 : :
447 : : /** Efficiently check whether a block is present in this chain. */
448 : 617841 : bool Contains(const CBlockIndex* pindex) const
449 : : {
450 : 617841 : return (*this)[pindex->nHeight] == pindex;
451 : : }
452 : :
453 : : /** Find the successor of a block in this chain, or nullptr if the given index is not found or is the tip. */
454 : 226081 : CBlockIndex* Next(const CBlockIndex* pindex) const
455 : : {
456 [ + - ]: 226081 : if (Contains(pindex))
457 : 226081 : return (*this)[pindex->nHeight + 1];
458 : : else
459 : 0 : return nullptr;
460 : 226081 : }
461 : :
462 : : /** Return the maximal height in the chain. Is equal to chain.Tip() ? chain.Tip()->nHeight : -1. */
463 : 1952091 : int Height() const
464 : : {
465 : 1952091 : return int(vChain.size()) - 1;
466 : : }
467 : :
468 : : /** Set/initialize a chain with a given tip. */
469 : : void SetTip(CBlockIndex& block);
470 : :
471 : : /** Return a CBlockLocator that refers to the tip in of this chain. */
472 : : CBlockLocator GetLocator() const;
473 : :
474 : : /** Find the last common block between this chain and a block index entry. */
475 : : const CBlockIndex* FindFork(const CBlockIndex* pindex) const;
476 : :
477 : : /** Find the earliest block with timestamp equal or greater than the given time and height equal or greater than the given height. */
478 : : CBlockIndex* FindEarliestAtLeast(int64_t nTime, int height) const;
479 : : };
480 : :
481 : : /** Get a locator for a block index entry. */
482 : : CBlockLocator GetLocator(const CBlockIndex* index);
483 : :
484 : : /** Construct a list of hash entries to put in a locator. */
485 : : std::vector<uint256> LocatorEntries(const CBlockIndex* index);
486 : :
487 : : #endif // BITCOIN_CHAIN_H
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