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BIP9 Implementation

Browse Source 
Inspired by former implementations by Eric Lombrozo and Rusty Russell, and
based on code by Jorge Timon.
This commit is contained in:
Pieter Wuille 2016-02-15 05:13:27 +01:00 committed by BtcDrak
parent ade85e126d
commit 6f83cf2adb
12 changed files with 345 additions and 19 deletions
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2
src/Makefile.am
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@ -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

2
src/chain.h
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@ -14,8 +14,6 @@
#include <vector>
#include <boost/foreach.hpp>
struct CDiskBlockPos
{
int nFile;

6
src/chainparams.cpp
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@ -81,6 +81,8 @@ public:
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 @@ public:
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 @@ public:
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;

28
src/consensus/params.h
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@ -7,8 +7,28 @@
#define BITCOIN_CONSENSUS_PARAMS_H
#include "uint256.h"
#include <map>
#include <string>
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;

2
src/init.cpp
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@ -496,7 +496,7 @@ std::string HelpMessage(HelpMessageMode mode)
strUsage += HelpMessageOpt("-blockmaxsize=<n>", strprintf(_("Set maximum block size in bytes (default: %d)"), DEFAULT_BLOCK_MAX_SIZE));
strUsage += HelpMessageOpt("-blockprioritysize=<n>", strprintf(_("Set maximum size of high-priority/low-fee transactions in bytes (default: %d)"), DEFAULT_BLOCK_PRIORITY_SIZE));
if (showDebug)
strUsage += HelpMessageOpt("-blockversion=<n>", strprintf("Override block version to test forking scenarios (default: %d)", (int)CBlock::CURRENT_VERSION));
strUsage += HelpMessageOpt("-blockversion=<n>", "Override block version to test forking scenarios");
strUsage += HelpMessageGroup(_("RPC server options:"));
strUsage += HelpMessageOpt("-server", _("Accept command line and JSON-RPC commands"));

80
src/main.cpp
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@ -34,6 +34,7 @@
#include "utilmoneystr.h"
#include "utilstrencodings.h"
#include "validationinterface.h"
#include "versionbits.h"
#include <sstream>
@ -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<int64_t>::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;

5
src/main.h
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@ -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.

11
src/miner.cpp
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@ -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();

3
src/primitives/block.h
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@ -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 @@ public:
void SetNull()
{
nVersion = CBlockHeader::CURRENT_VERSION;
nVersion = 0;
hashPrevBlock.SetNull();
hashMerkleRoot.SetNull();
nTime = 0;

33
src/test/miner_tests.cpp
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@ -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);

133
src/versionbits.cpp Normal file
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@ -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<const CBlockIndex*> 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();
}
}

59
src/versionbits.h Normal file
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@ -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 <map>
/** 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<const CBlockIndex*, ThresholdState> 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