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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "pow.h"
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#include "arith_uint256.h"
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#include "chain.h"
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#include "chainparams.h"
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#include "crypto/equihash.h"
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#include "primitives/block.h"
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#include "streams.h"
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#include "uint256.h"
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Split up util.cpp/h
Split up util.cpp/h into:
- string utilities (hex, base32, base64): no internal dependencies, no dependency on boost (apart from foreach)
- money utilities (parsesmoney, formatmoney)
- time utilities (gettime*, sleep, format date):
- and the rest (logging, argument parsing, config file parsing)
The latter is basically the environment and OS handling,
and is stripped of all utility functions, so we may want to
rename it to something else than util.cpp/h for clarity (Matt suggested
osinterface).
Breaks dependency of sha256.cpp on all the things pulled in by util.
10 years ago
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#include "util.h"
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#include "sodium.h"
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unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
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{
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unsigned int nProofOfWorkLimit = UintToArith256(params.powLimit).GetCompact();
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// Genesis block
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if (pindexLast == NULL)
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return nProofOfWorkLimit;
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const CBlockIndex* pindexBits = pindexLast;
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{
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if (params.fPowAllowMinDifficultyBlocks)
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{
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// Special difficulty rule for testnet:
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// If the new block's timestamp is more than 2* 2.5 minutes
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// then allow mining of a min-difficulty block.
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if (pblock->GetBlockTime() > pindexLast->GetBlockTime() + params.nPowTargetSpacing*2)
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return nProofOfWorkLimit;
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else {
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// Get the last non-min-difficulty (or at worst the genesis difficulty)
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while (pindexBits->pprev && pindexBits->nBits == nProofOfWorkLimit)
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pindexBits = pindexBits->pprev;
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}
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}
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}
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// Find the first block in the averaging interval
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const CBlockIndex* pindexFirst = pindexLast;
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arith_uint256 bnTot {0};
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for (int i = 0; pindexFirst && i < params.nPowAveragingWindow; i++) {
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arith_uint256 bnTmp;
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bnTmp.SetCompact(pindexFirst->nBits);
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bnTot += bnTmp;
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pindexFirst = pindexFirst->pprev;
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}
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// Check we have enough blocks
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if (pindexFirst == NULL)
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return nProofOfWorkLimit;
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arith_uint256 bnAvg {bnTot / params.nPowAveragingWindow};
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return CalculateNextWorkRequired(bnAvg, pindexLast->GetMedianTimePast(), pindexFirst->GetMedianTimePast(), params);
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}
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unsigned int CalculateNextWorkRequired(arith_uint256 bnAvg,
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int64_t nLastBlockTime, int64_t nFirstBlockTime,
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const Consensus::Params& params)
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{
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// Limit adjustment step
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// Use medians to prevent time-warp attacks
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int64_t nActualTimespan = nLastBlockTime - nFirstBlockTime;
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LogPrint("pow", " nActualTimespan = %d before dampening\n", nActualTimespan);
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nActualTimespan = params.AveragingWindowTimespan() + (nActualTimespan - params.AveragingWindowTimespan())/4;
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LogPrint("pow", " nActualTimespan = %d before bounds\n", nActualTimespan);
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if (nActualTimespan < params.MinActualTimespan())
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nActualTimespan = params.MinActualTimespan();
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if (nActualTimespan > params.MaxActualTimespan())
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nActualTimespan = params.MaxActualTimespan();
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// Retarget
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const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
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arith_uint256 bnNew {bnAvg};
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bnNew /= params.AveragingWindowTimespan();
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bnNew *= nActualTimespan;
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if (bnNew > bnPowLimit)
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bnNew = bnPowLimit;
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/// debug print
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LogPrint("pow", "GetNextWorkRequired RETARGET\n");
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LogPrint("pow", "params.AveragingWindowTimespan() = %d nActualTimespan = %d\n", params.AveragingWindowTimespan(), nActualTimespan);
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LogPrint("pow", "Current average: %08x %s\n", bnAvg.GetCompact(), bnAvg.ToString());
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LogPrint("pow", "After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString());
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return bnNew.GetCompact();
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}
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bool CheckEquihashSolution(const CBlockHeader *pblock, const CChainParams& params)
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{
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unsigned int n = params.EquihashN();
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unsigned int k = params.EquihashK();
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// Hash state
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crypto_generichash_blake2b_state state;
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EhInitialiseState(n, k, state);
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// I = the block header minus nonce and solution.
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CEquihashInput I{*pblock};
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// I||V
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CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
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ss << I;
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ss << pblock->nNonce;
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// H(I||V||...
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crypto_generichash_blake2b_update(&state, (unsigned char*)&ss[0], ss.size());
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bool isValid;
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EhIsValidSolution(n, k, state, pblock->nSolution, isValid);
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if (!isValid)
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return error("CheckEquihashSolution(): invalid solution");
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return true;
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}
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bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params& params)
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{
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bool fNegative;
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bool fOverflow;
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arith_uint256 bnTarget;
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bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
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// Check range
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if (fNegative || bnTarget == 0 || fOverflow || bnTarget > UintToArith256(params.powLimit))
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return error("CheckProofOfWork(): nBits below minimum work");
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// Check proof of work matches claimed amount
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if (UintToArith256(hash) > bnTarget)
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return error("CheckProofOfWork(): hash doesn't match nBits");
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return true;
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}
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arith_uint256 GetBlockProof(const CBlockIndex& block)
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{
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arith_uint256 bnTarget;
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bool fNegative;
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bool fOverflow;
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bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
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if (fNegative || fOverflow || bnTarget == 0)
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return 0;
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// We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
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// as it's too large for a arith_uint256. However, as 2**256 is at least as large
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// as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,
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// or ~bnTarget / (nTarget+1) + 1.
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return (~bnTarget / (bnTarget + 1)) + 1;
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}
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int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)
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{
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arith_uint256 r;
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int sign = 1;
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if (to.nChainWork > from.nChainWork) {
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r = to.nChainWork - from.nChainWork;
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} else {
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r = from.nChainWork - to.nChainWork;
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sign = -1;
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}
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r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
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if (r.bits() > 63) {
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return sign * std::numeric_limits<int64_t>::max();
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}
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return sign * r.GetLow64();
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}
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