From 6f83cf2adb2fd73cfeaa8ef67054ea8a0e4ef4db Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Mon, 15 Feb 2016 05:13:27 +0100 Subject: [PATCH] BIP9 Implementation Inspired by former implementations by Eric Lombrozo and Rusty Russell, and based on code by Jorge Timon. --- src/Makefile.am | 2 + src/chain.h | 2 - src/chainparams.cpp | 6 ++ src/consensus/params.h | 28 +++++++++ src/init.cpp | 2 +- src/main.cpp | 80 +++++++++++++++++++++-- src/main.h | 5 ++ src/miner.cpp | 11 ++-- src/primitives/block.h | 3 +- src/test/miner_tests.cpp | 33 +++++++++- src/versionbits.cpp | 133 +++++++++++++++++++++++++++++++++++++++ src/versionbits.h | 59 +++++++++++++++++ 12 files changed, 345 insertions(+), 19 deletions(-) create mode 100644 src/versionbits.cpp create mode 100644 src/versionbits.h diff --git a/src/Makefile.am b/src/Makefile.am index 4c12e550b4d65..52316a9fd7b7f 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -163,6 +163,7 @@ BITCOIN_CORE_H = \ utiltime.h \ validationinterface.h \ version.h \ + versionbits.h \ wallet/crypter.h \ wallet/db.h \ wallet/wallet.h \ @@ -214,6 +215,7 @@ libbitcoin_server_a_SOURCES = \ txdb.cpp \ txmempool.cpp \ validationinterface.cpp \ + versionbits.cpp \ $(BITCOIN_CORE_H) if ENABLE_ZMQ diff --git a/src/chain.h b/src/chain.h index b9b1b9306f26c..ae6c4338d6102 100644 --- a/src/chain.h +++ b/src/chain.h @@ -14,8 +14,6 @@ #include -#include - struct CDiskBlockPos { int nFile; diff --git a/src/chainparams.cpp b/src/chainparams.cpp index 9cf99492c912e..b911ab3f619ce 100644 --- a/src/chainparams.cpp +++ b/src/chainparams.cpp @@ -81,6 +81,8 @@ class CMainParams : public CChainParams { consensus.nPowTargetSpacing = 10 * 60; consensus.fPowAllowMinDifficultyBlocks = false; consensus.fPowNoRetargeting = false; + consensus.nRuleChangeActivationThreshold = 1916; // 95% of 2016 + consensus.nMinerConfirmationWindow = 2016; // nPowTargetTimespan / nPowTargetSpacing /** * The message start string is designed to be unlikely to occur in normal data. * The characters are rarely used upper ASCII, not valid as UTF-8, and produce @@ -163,6 +165,8 @@ class CTestNetParams : public CChainParams { consensus.nPowTargetSpacing = 10 * 60; consensus.fPowAllowMinDifficultyBlocks = true; consensus.fPowNoRetargeting = false; + consensus.nRuleChangeActivationThreshold = 1512; // 75% for testchains + consensus.nMinerConfirmationWindow = 2016; // nPowTargetTimespan / nPowTargetSpacing pchMessageStart[0] = 0x0b; pchMessageStart[1] = 0x11; pchMessageStart[2] = 0x09; @@ -227,6 +231,8 @@ class CRegTestParams : public CChainParams { consensus.nPowTargetSpacing = 10 * 60; consensus.fPowAllowMinDifficultyBlocks = true; consensus.fPowNoRetargeting = true; + consensus.nRuleChangeActivationThreshold = 108; // 75% for testchains + consensus.nMinerConfirmationWindow = 144; // Faster than normal for regtest (144 instead of 2016) pchMessageStart[0] = 0xfa; pchMessageStart[1] = 0xbf; diff --git a/src/consensus/params.h b/src/consensus/params.h index 335750fe80724..d5039211a30be 100644 --- a/src/consensus/params.h +++ b/src/consensus/params.h @@ -7,8 +7,28 @@ #define BITCOIN_CONSENSUS_PARAMS_H #include "uint256.h" +#include +#include namespace Consensus { + +enum DeploymentPos +{ + MAX_VERSION_BITS_DEPLOYMENTS = 0, +}; + +/** + * Struct for each individual consensus rule change using BIP9. + */ +struct BIP9Deployment { + /** Bit position to select the particular bit in nVersion. */ + int bit; + /** Start MedianTime for version bits miner confirmation. Can be a date in the past */ + int64_t nStartTime; + /** Timeout/expiry MedianTime for the deployment attempt. */ + int64_t nTimeout; +}; + /** * Parameters that influence chain consensus. */ @@ -22,6 +42,14 @@ struct Params { /** Block height and hash at which BIP34 becomes active */ int BIP34Height; uint256 BIP34Hash; + /** + * Minimum blocks including miner confirmation of the total of 2016 blocks in a retargetting period, + * (nPowTargetTimespan / nPowTargetSpacing) which is also used for BIP9 deployments. + * Examples: 1916 for 95%, 1512 for testchains. + */ + uint32_t nRuleChangeActivationThreshold; + uint32_t nMinerConfirmationWindow; + BIP9Deployment vDeployments[MAX_VERSION_BITS_DEPLOYMENTS]; /** Proof of work parameters */ uint256 powLimit; bool fPowAllowMinDifficultyBlocks; diff --git a/src/init.cpp b/src/init.cpp index 71a9eae861dc2..2b7da4ee8c134 100644 --- a/src/init.cpp +++ b/src/init.cpp @@ -496,7 +496,7 @@ std::string HelpMessage(HelpMessageMode mode) strUsage += HelpMessageOpt("-blockmaxsize=", strprintf(_("Set maximum block size in bytes (default: %d)"), DEFAULT_BLOCK_MAX_SIZE)); strUsage += HelpMessageOpt("-blockprioritysize=", strprintf(_("Set maximum size of high-priority/low-fee transactions in bytes (default: %d)"), DEFAULT_BLOCK_PRIORITY_SIZE)); if (showDebug) - strUsage += HelpMessageOpt("-blockversion=", strprintf("Override block version to test forking scenarios (default: %d)", (int)CBlock::CURRENT_VERSION)); + strUsage += HelpMessageOpt("-blockversion=", "Override block version to test forking scenarios"); strUsage += HelpMessageGroup(_("RPC server options:")); strUsage += HelpMessageOpt("-server", _("Accept command line and JSON-RPC commands")); diff --git a/src/main.cpp b/src/main.cpp index d6eeceaaf7d78..542f37876a890 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -34,6 +34,7 @@ #include "utilmoneystr.h" #include "utilstrencodings.h" #include "validationinterface.h" +#include "versionbits.h" #include @@ -2135,6 +2136,51 @@ void PartitionCheck(bool (*initialDownloadCheck)(), CCriticalSection& cs, const } } +// Protected by cs_main +static VersionBitsCache versionbitscache; + +int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params) +{ + LOCK(cs_main); + int32_t nVersion = VERSIONBITS_TOP_BITS; + + for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; i++) { + ThresholdState state = VersionBitsState(pindexPrev, params, (Consensus::DeploymentPos)i, versionbitscache); + if (state == THRESHOLD_LOCKED_IN || state == THRESHOLD_STARTED) { + nVersion |= VersionBitsMask(params, (Consensus::DeploymentPos)i); + } + } + + return nVersion; +} + +/** + * Threshold condition checker that triggers when unknown versionbits are seen on the network. + */ +class WarningBitsConditionChecker : public AbstractThresholdConditionChecker +{ +private: + int bit; + +public: + WarningBitsConditionChecker(int bitIn) : bit(bitIn) {} + + int64_t BeginTime(const Consensus::Params& params) const { return 0; } + int64_t EndTime(const Consensus::Params& params) const { return std::numeric_limits::max(); } + int Period(const Consensus::Params& params) const { return params.nMinerConfirmationWindow; } + int Threshold(const Consensus::Params& params) const { return params.nRuleChangeActivationThreshold; } + + bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const + { + return ((pindex->nVersion & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) && + ((pindex->nVersion >> bit) & 1) != 0 && + ((ComputeBlockVersion(pindex->pprev, params) >> bit) & 1) == 0; + } +}; + +// Protected by cs_main +static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS]; + static int64_t nTimeCheck = 0; static int64_t nTimeForks = 0; static int64_t nTimeVerify = 0; @@ -2503,24 +2549,42 @@ void static UpdateTip(CBlockIndex *pindexNew) { // Check the version of the last 100 blocks to see if we need to upgrade: static bool fWarned = false; - if (!IsInitialBlockDownload() && !fWarned) + if (!IsInitialBlockDownload()) { int nUpgraded = 0; const CBlockIndex* pindex = chainActive.Tip(); + for (int bit = 0; bit < VERSIONBITS_NUM_BITS; bit++) { + WarningBitsConditionChecker checker(bit); + ThresholdState state = checker.GetStateFor(pindex, chainParams.GetConsensus(), warningcache[bit]); + if (state == THRESHOLD_ACTIVE || state == THRESHOLD_LOCKED_IN) { + if (state == THRESHOLD_ACTIVE) { + strMiscWarning = strprintf(_("Warning: unknown new rules activated (versionbit %i)"), bit); + if (!fWarned) { + CAlert::Notify(strMiscWarning, true); + fWarned = true; + } + } else { + LogPrintf("%s: unknown new rules are about to activate (versionbit %i)\n", __func__, bit); + } + } + } for (int i = 0; i < 100 && pindex != NULL; i++) { - if (pindex->nVersion > CBlock::CURRENT_VERSION) + int32_t nExpectedVersion = ComputeBlockVersion(pindex->pprev, chainParams.GetConsensus()); + if (pindex->nVersion > VERSIONBITS_LAST_OLD_BLOCK_VERSION && (pindex->nVersion & ~nExpectedVersion) != 0) ++nUpgraded; pindex = pindex->pprev; } if (nUpgraded > 0) - LogPrintf("%s: %d of last 100 blocks above version %d\n", __func__, nUpgraded, (int)CBlock::CURRENT_VERSION); + LogPrintf("%s: %d of last 100 blocks have unexpected version\n", __func__, nUpgraded); if (nUpgraded > 100/2) { // strMiscWarning is read by GetWarnings(), called by Qt and the JSON-RPC code to warn the user: - strMiscWarning = _("Warning: This version is obsolete; upgrade required!"); - CAlert::Notify(strMiscWarning, true); - fWarned = true; + strMiscWarning = _("Warning: Unknown block versions being mined! It's possible unknown rules are in effect"); + if (!fWarned) { + CAlert::Notify(strMiscWarning, true); + fWarned = true; + } } } } @@ -3839,6 +3903,10 @@ void UnloadBlockIndex() setDirtyFileInfo.clear(); mapNodeState.clear(); recentRejects.reset(NULL); + versionbitscache.Clear(); + for (int b = 0; b < VERSIONBITS_NUM_BITS; b++) { + warningcache[b].clear(); + } BOOST_FOREACH(BlockMap::value_type& entry, mapBlockIndex) { delete entry.second; diff --git a/src/main.h b/src/main.h index 3793f55ba2e99..8c6a51cacdfaa 100644 --- a/src/main.h +++ b/src/main.h @@ -528,6 +528,11 @@ extern CBlockTreeDB *pblocktree; */ int GetSpendHeight(const CCoinsViewCache& inputs); +/** + * Determine what nVersion a new block should use. + */ +int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params); + /** Reject codes greater or equal to this can be returned by AcceptToMemPool * for transactions, to signal internal conditions. They cannot and should not * be sent over the P2P network. diff --git a/src/miner.cpp b/src/miner.cpp index c454c0279c200..d095d418feac7 100644 --- a/src/miner.cpp +++ b/src/miner.cpp @@ -79,11 +79,6 @@ CBlockTemplate* CreateNewBlock(const CChainParams& chainparams, const CScript& s return NULL; CBlock *pblock = &pblocktemplate->block; // pointer for convenience - // -regtest only: allow overriding block.nVersion with - // -blockversion=N to test forking scenarios - if (chainparams.MineBlocksOnDemand()) - pblock->nVersion = GetArg("-blockversion", pblock->nVersion); - // Create coinbase tx CMutableTransaction txNew; txNew.vin.resize(1); @@ -137,6 +132,12 @@ CBlockTemplate* CreateNewBlock(const CChainParams& chainparams, const CScript& s pblock->nTime = GetAdjustedTime(); const int64_t nMedianTimePast = pindexPrev->GetMedianTimePast(); + pblock->nVersion = ComputeBlockVersion(pindexPrev, chainparams.GetConsensus()); + // -regtest only: allow overriding block.nVersion with + // -blockversion=N to test forking scenarios + if (chainparams.MineBlocksOnDemand()) + pblock->nVersion = GetArg("-blockversion", pblock->nVersion); + int64_t nLockTimeCutoff = (STANDARD_LOCKTIME_VERIFY_FLAGS & LOCKTIME_MEDIAN_TIME_PAST) ? nMedianTimePast : pblock->GetBlockTime(); diff --git a/src/primitives/block.h b/src/primitives/block.h index 0e93399c08e47..42276b2bc26bc 100644 --- a/src/primitives/block.h +++ b/src/primitives/block.h @@ -21,7 +21,6 @@ class CBlockHeader { public: // header - static const int32_t CURRENT_VERSION=4; int32_t nVersion; uint256 hashPrevBlock; uint256 hashMerkleRoot; @@ -49,7 +48,7 @@ class CBlockHeader void SetNull() { - nVersion = CBlockHeader::CURRENT_VERSION; + nVersion = 0; hashPrevBlock.SetNull(); hashMerkleRoot.SetNull(); nTime = 0; diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp index f3297e074de48..ab6485081ceed 100644 --- a/src/test/miner_tests.cpp +++ b/src/test/miner_tests.cpp @@ -247,13 +247,40 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity) // subsidy changing int nHeight = chainActive.Height(); - chainActive.Tip()->nHeight = 209999; + // Create an actual 209999-long block chain (without valid blocks). + while (chainActive.Tip()->nHeight < 209999) { + CBlockIndex* prev = chainActive.Tip(); + CBlockIndex* next = new CBlockIndex(); + next->phashBlock = new uint256(GetRandHash()); + pcoinsTip->SetBestBlock(next->GetBlockHash()); + next->pprev = prev; + next->nHeight = prev->nHeight + 1; + next->BuildSkip(); + chainActive.SetTip(next); + } BOOST_CHECK(pblocktemplate = CreateNewBlock(chainparams, scriptPubKey)); delete pblocktemplate; - chainActive.Tip()->nHeight = 210000; + // Extend to a 210000-long block chain. + while (chainActive.Tip()->nHeight < 210000) { + CBlockIndex* prev = chainActive.Tip(); + CBlockIndex* next = new CBlockIndex(); + next->phashBlock = new uint256(GetRandHash()); + pcoinsTip->SetBestBlock(next->GetBlockHash()); + next->pprev = prev; + next->nHeight = prev->nHeight + 1; + next->BuildSkip(); + chainActive.SetTip(next); + } BOOST_CHECK(pblocktemplate = CreateNewBlock(chainparams, scriptPubKey)); delete pblocktemplate; - chainActive.Tip()->nHeight = nHeight; + // Delete the dummy blocks again. + while (chainActive.Tip()->nHeight > nHeight) { + CBlockIndex* del = chainActive.Tip(); + chainActive.SetTip(del->pprev); + pcoinsTip->SetBestBlock(del->pprev->GetBlockHash()); + delete del->phashBlock; + delete del; + } // non-final txs in mempool SetMockTime(chainActive.Tip()->GetMedianTimePast()+1); diff --git a/src/versionbits.cpp b/src/versionbits.cpp new file mode 100644 index 0000000000000..fbb60c0fc598e --- /dev/null +++ b/src/versionbits.cpp @@ -0,0 +1,133 @@ +// Copyright (c) 2016 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "versionbits.h" + +ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const +{ + int nPeriod = Period(params); + int nThreshold = Threshold(params); + int64_t nTimeStart = BeginTime(params); + int64_t nTimeTimeout = EndTime(params); + + // A block's state is always the same as that of the first of its period, so it is computed based on a pindexPrev whose height equals a multiple of nPeriod - 1. + if (pindexPrev != NULL) { + pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - ((pindexPrev->nHeight + 1) % nPeriod)); + } + + // Walk backwards in steps of nPeriod to find a pindexPrev whose information is known + std::vector vToCompute; + while (cache.count(pindexPrev) == 0) { + if (pindexPrev == NULL) { + // The genesis block is by definition defined. + cache[pindexPrev] = THRESHOLD_DEFINED; + break; + } + if (pindexPrev->GetMedianTimePast() < nTimeStart) { + // Optimizaton: don't recompute down further, as we know every earlier block will be before the start time + cache[pindexPrev] = THRESHOLD_DEFINED; + break; + } + vToCompute.push_back(pindexPrev); + pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - nPeriod); + } + + // At this point, cache[pindexPrev] is known + assert(cache.count(pindexPrev)); + ThresholdState state = cache[pindexPrev]; + + // Now walk forward and compute the state of descendants of pindexPrev + while (!vToCompute.empty()) { + ThresholdState stateNext = state; + pindexPrev = vToCompute.back(); + vToCompute.pop_back(); + + switch (state) { + case THRESHOLD_DEFINED: { + if (pindexPrev->GetMedianTimePast() >= nTimeTimeout) { + stateNext = THRESHOLD_FAILED; + } else if (pindexPrev->GetMedianTimePast() >= nTimeStart) { + stateNext = THRESHOLD_STARTED; + } + break; + } + case THRESHOLD_STARTED: { + if (pindexPrev->GetMedianTimePast() >= nTimeTimeout) { + stateNext = THRESHOLD_FAILED; + break; + } + // We need to count + const CBlockIndex* pindexCount = pindexPrev; + int count = 0; + for (int i = 0; i < nPeriod; i++) { + if (Condition(pindexCount, params)) { + count++; + } + pindexCount = pindexCount->pprev; + } + if (count >= nThreshold) { + stateNext = THRESHOLD_LOCKED_IN; + } + break; + } + case THRESHOLD_LOCKED_IN: { + // Always progresses into ACTIVE. + stateNext = THRESHOLD_ACTIVE; + break; + } + case THRESHOLD_FAILED: + case THRESHOLD_ACTIVE: { + // Nothing happens, these are terminal states. + break; + } + } + cache[pindexPrev] = state = stateNext; + } + + return state; +} + +namespace +{ +/** + * Class to implement versionbits logic. + */ +class VersionBitsConditionChecker : public AbstractThresholdConditionChecker { +private: + const Consensus::DeploymentPos id; + +protected: + int64_t BeginTime(const Consensus::Params& params) const { return params.vDeployments[id].nStartTime; } + int64_t EndTime(const Consensus::Params& params) const { return params.vDeployments[id].nTimeout; } + int Period(const Consensus::Params& params) const { return params.nMinerConfirmationWindow; } + int Threshold(const Consensus::Params& params) const { return params.nRuleChangeActivationThreshold; } + + bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const + { + return (((pindex->nVersion & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) && (pindex->nVersion & Mask(params)) != 0); + } + +public: + VersionBitsConditionChecker(Consensus::DeploymentPos id_) : id(id_) {} + uint32_t Mask(const Consensus::Params& params) const { return ((uint32_t)1) << params.vDeployments[id].bit; } +}; + +} + +ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache) +{ + return VersionBitsConditionChecker(pos).GetStateFor(pindexPrev, params, cache.caches[pos]); +} + +uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos) +{ + return VersionBitsConditionChecker(pos).Mask(params); +} + +void VersionBitsCache::Clear() +{ + for (unsigned int d = 0; d < Consensus::MAX_VERSION_BITS_DEPLOYMENTS; d++) { + caches[d].clear(); + } +} diff --git a/src/versionbits.h b/src/versionbits.h new file mode 100644 index 0000000000000..04f4738272796 --- /dev/null +++ b/src/versionbits.h @@ -0,0 +1,59 @@ +// Copyright (c) 2016 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_CONSENSUS_VERSIONBITS +#define BITCOIN_CONSENSUS_VERSIONBITS + +#include "chain.h" +#include + +/** What block version to use for new blocks (pre versionbits) */ +static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4; +/** What bits to set in version for versionbits blocks */ +static const int32_t VERSIONBITS_TOP_BITS = 0x20000000UL; +/** What bitmask determines whether versionbits is in use */ +static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL; +/** Total bits available for versionbits */ +static const int32_t VERSIONBITS_NUM_BITS = 29; + +enum ThresholdState { + THRESHOLD_DEFINED, + THRESHOLD_STARTED, + THRESHOLD_LOCKED_IN, + THRESHOLD_ACTIVE, + THRESHOLD_FAILED, +}; + +// A map that gives the state for blocks whose height is a multiple of Period(). +// The map is indexed by the block's parent, however, so all keys in the map +// will either be NULL or a block with (height + 1) % Period() == 0. +typedef std::map ThresholdConditionCache; + +/** + * Abstract class that implements BIP9-style threshold logic, and caches results. + */ +class AbstractThresholdConditionChecker { +protected: + virtual bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const =0; + virtual int64_t BeginTime(const Consensus::Params& params) const =0; + virtual int64_t EndTime(const Consensus::Params& params) const =0; + virtual int Period(const Consensus::Params& params) const =0; + virtual int Threshold(const Consensus::Params& params) const =0; + +public: + // Note that the function below takes a pindexPrev as input: they compute information for block B based on its parent. + ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const; +}; + +struct VersionBitsCache +{ + ThresholdConditionCache caches[Consensus::MAX_VERSION_BITS_DEPLOYMENTS]; + + void Clear(); +}; + +ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache); +uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos); + +#endif