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Merge pull request #534 from gavinandresen/DoSorphans

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Denial-of-service prevention: low-difficulty blocks
This commit is contained in:
Gavin Andresen 2011-12-01 12:42:02 -08:00
commit 43f20bb3c2
13 changed files with 247 additions and 31 deletions
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2
bitcoin-qt.pro
View file

@ -88,6 +88,7 @@ HEADERS += src/qt/bitcoingui.h \
src/qt/bitcoinaddressvalidator.h \
src/base58.h \
src/bignum.h \
src/checkpoints.h \
src/util.h \
src/uint256.h \
src/serialize.h \
@ -152,6 +153,7 @@ SOURCES += src/qt/bitcoin.cpp src/qt/bitcoingui.cpp \
src/init.cpp \
src/net.cpp \
src/irc.cpp \
src/checkpoints.cpp \
src/db.cpp \
src/json/json_spirit_writer.cpp \
src/json/json_spirit_value.cpp \

65
src/checkpoints.cpp Normal file
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@ -0,0 +1,65 @@
// Copyright (c) 2011 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#include <boost/assign/list_of.hpp> // for 'map_list_of()'
#include <boost/foreach.hpp>
#include "headers.h"
#include "checkpoints.h"
namespace Checkpoints
{
typedef std::map<int, uint256> MapCheckpoints;
//
// What makes a good checkpoint block?
// + Is surrounded by blocks with reasonable timestamps
// (no blocks before with a timestamp after, none after with
// timestamp before)
// + Contains no strange transactions
//
static MapCheckpoints mapCheckpoints =
boost::assign::map_list_of
( 11111, uint256("0x0000000069e244f73d78e8fd29ba2fd2ed618bd6fa2ee92559f542fdb26e7c1d"))
( 33333, uint256("0x000000002dd5588a74784eaa7ab0507a18ad16a236e7b1ce69f00d7ddfb5d0a6"))
( 68555, uint256("0x00000000001e1b4903550a0b96e9a9405c8a95f387162e4944e8d9fbe501cd6a"))
( 70567, uint256("0x00000000006a49b14bcf27462068f1264c961f11fa2e0eddd2be0791e1d4124a"))
( 74000, uint256("0x0000000000573993a3c9e41ce34471c079dcf5f52a0e824a81e7f953b8661a20"))
(105000, uint256("0x00000000000291ce28027faea320c8d2b054b2e0fe44a773f3eefb151d6bdc97"))
(118000, uint256("0x000000000000774a7f8a7a12dc906ddb9e17e75d684f15e00f8767f9e8f36553"))
(134444, uint256("0x00000000000005b12ffd4cd315cd34ffd4a594f430ac814c91184a0d42d2b0fe"))
(140700, uint256("0x000000000000033b512028abb90e1626d8b346fd0ed598ac0a3c371138dce2bd"))
;
bool CheckBlock(int nHeight, const uint256& hash)
{
if (fTestNet) return true; // Testnet has no checkpoints
MapCheckpoints::const_iterator i = mapCheckpoints.find(nHeight);
if (i == mapCheckpoints.end()) return true;
return hash == i->second;
}
int GetTotalBlocksEstimate()
{
if (fTestNet) return 0;
return mapCheckpoints.rbegin()->first;
}
CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
{
if (fTestNet) return NULL;
int64 nResult;
BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, mapCheckpoints)
{
const uint256& hash = i.second;
std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
if (t != mapBlockIndex.end())
return t->second;
}
return NULL;
}
}

29
src/checkpoints.h Normal file
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@ -0,0 +1,29 @@
// Copyright (c) 2011 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_CHECKPOINT_H
#define BITCOIN_CHECKPOINT_H
#include <map>
#include "util.h"
class uint256;
class CBlockIndex;
//
// Block-chain checkpoints are compiled-in sanity checks.
// They are updated every release or three.
//
namespace Checkpoints
{
// Returns true if block passes checkpoint checks
bool CheckBlock(int nHeight, const uint256& hash);
// Return conservative estimate of total number of blocks, 0 if unknown
int GetTotalBlocksEstimate();
// Returns last CBlockIndex* in mapBlockIndex that is a checkpoint
CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex);
}
#endif

81
src/main.cpp
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@ -3,6 +3,7 @@
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#include "headers.h"
#include "checkpoints.h"
#include "db.h"
#include "net.h"
#include "init.h"
@ -29,7 +30,6 @@ map<COutPoint, CInPoint> mapNextTx;
map<uint256, CBlockIndex*> mapBlockIndex;
uint256 hashGenesisBlock("0x000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f");
static CBigNum bnProofOfWorkLimit(~uint256(0) >> 32);
const int nTotalBlocksEstimate = 140700; // Conservative estimate of total nr of blocks on main chain
const int nInitialBlockThreshold = 120; // Regard blocks up until N-threshold as "initial download"
CBlockIndex* pindexGenesisBlock = NULL;
int nBestHeight = -1;
@ -659,11 +659,32 @@ int64 static GetBlockValue(int nHeight, int64 nFees)
return nSubsidy + nFees;
}
static const int64 nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
static const int64 nTargetSpacing = 10 * 60;
static const int64 nInterval = nTargetTimespan / nTargetSpacing;
//
// minimum amount of work that could possibly be required nTime after
// minimum work required was nBase
//
unsigned int ComputeMinWork(unsigned int nBase, int64 nTime)
{
CBigNum bnResult;
bnResult.SetCompact(nBase);
while (nTime > 0 && bnResult < bnProofOfWorkLimit)
{
// Maximum 400% adjustment...
bnResult *= 4;
// ... in best-case exactly 4-times-normal target time
nTime -= nTargetTimespan*4;
}
if (bnResult > bnProofOfWorkLimit)
bnResult = bnProofOfWorkLimit;
return bnResult.GetCompact();
}
unsigned int static GetNextWorkRequired(const CBlockIndex* pindexLast)
{
const int64 nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
const int64 nTargetSpacing = 10 * 60;
const int64 nInterval = nTargetTimespan / nTargetSpacing;
// Genesis block
if (pindexLast == NULL)
@ -721,28 +742,15 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
return true;
}
// Return conservative estimate of total number of blocks, 0 if unknown
int GetTotalBlocksEstimate()
{
if(fTestNet)
{
return 0;
}
else
{
return nTotalBlocksEstimate;
}
}
// Return maximum amount of blocks that other nodes claim to have
int GetNumBlocksOfPeers()
{
return std::max(cPeerBlockCounts.median(), GetTotalBlocksEstimate());
return std::max(cPeerBlockCounts.median(), Checkpoints::GetTotalBlocksEstimate());
}
bool IsInitialBlockDownload()
{
if (pindexBest == NULL || nBestHeight < (GetTotalBlocksEstimate()-nInitialBlockThreshold))
if (pindexBest == NULL || nBestHeight < (Checkpoints::GetTotalBlocksEstimate()-nInitialBlockThreshold))
return true;
static int64 nLastUpdate;
static CBlockIndex* pindexLastBest;
@ -1317,17 +1325,8 @@ bool CBlock::AcceptBlock()
return DoS(10, error("AcceptBlock() : contains a non-final transaction"));
// Check that the block chain matches the known block chain up to a checkpoint
if (!fTestNet)
if ((nHeight == 11111 && hash != uint256("0x0000000069e244f73d78e8fd29ba2fd2ed618bd6fa2ee92559f542fdb26e7c1d")) ||
(nHeight == 33333 && hash != uint256("0x000000002dd5588a74784eaa7ab0507a18ad16a236e7b1ce69f00d7ddfb5d0a6")) ||
(nHeight == 68555 && hash != uint256("0x00000000001e1b4903550a0b96e9a9405c8a95f387162e4944e8d9fbe501cd6a")) ||
(nHeight == 70567 && hash != uint256("0x00000000006a49b14bcf27462068f1264c961f11fa2e0eddd2be0791e1d4124a")) ||
(nHeight == 74000 && hash != uint256("0x0000000000573993a3c9e41ce34471c079dcf5f52a0e824a81e7f953b8661a20")) ||
(nHeight == 105000 && hash != uint256("0x00000000000291ce28027faea320c8d2b054b2e0fe44a773f3eefb151d6bdc97")) ||
(nHeight == 118000 && hash != uint256("0x000000000000774a7f8a7a12dc906ddb9e17e75d684f15e00f8767f9e8f36553")) ||
(nHeight == 134444 && hash != uint256("0x00000000000005b12ffd4cd315cd34ffd4a594f430ac814c91184a0d42d2b0fe")) ||
(nHeight == 140700 && hash != uint256("0x000000000000033b512028abb90e1626d8b346fd0ed598ac0a3c371138dce2bd")))
return DoS(100, error("AcceptBlock() : rejected by checkpoint lockin at %d", nHeight));
if (!Checkpoints::CheckBlock(nHeight, hash))
return DoS(100, error("AcceptBlock() : rejected by checkpoint lockin at %d", nHeight));
// Write block to history file
if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK)))
@ -1362,6 +1361,28 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
if (!pblock->CheckBlock())
return error("ProcessBlock() : CheckBlock FAILED");
CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint(mapBlockIndex);
if (pcheckpoint && pblock->hashPrevBlock != hashBestChain)
{
// Extra checks to prevent "fill up memory by spamming with bogus blocks"
int64 deltaTime = pblock->GetBlockTime() - pcheckpoint->nTime;
if (deltaTime < 0)
{
pfrom->Misbehaving(100);
return error("ProcessBlock() : block with timestamp before last checkpoint");
}
CBigNum bnNewBlock;
bnNewBlock.SetCompact(pblock->nBits);
CBigNum bnRequired;
bnRequired.SetCompact(ComputeMinWork(pcheckpoint->nBits, deltaTime));
if (bnNewBlock > bnRequired)
{
pfrom->Misbehaving(100);
return error("ProcessBlock() : block with too little proof-of-work");
}
}
// If don't already have its previous block, shunt it off to holding area until we get it
if (!mapBlockIndex.count(pblock->hashPrevBlock))
{

2
src/main.h
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@ -99,7 +99,7 @@ void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int&
void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1);
bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey);
bool CheckProofOfWork(uint256 hash, unsigned int nBits);
int GetTotalBlocksEstimate();
unsigned int ComputeMinWork(unsigned int nBase, int64 nTime);
int GetNumBlocksOfPeers();
bool IsInitialBlockDownload();
std::string GetWarnings(std::string strFor);

2
src/makefile.linux-mingw
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@ -32,6 +32,7 @@ CFLAGS=-O2 -w -Wno-invalid-offsetof -Wformat $(DEBUGFLAGS) $(DEFS) $(INCLUDEPATH
HEADERS = \
base58.h \
bignum.h \
checkpoints.h \
crypter.h \
db.h \
headers.h \
@ -61,6 +62,7 @@ endif
LIBS += -l mingwthrd -l kernel32 -l user32 -l gdi32 -l comdlg32 -l winspool -l winmm -l shell32 -l comctl32 -l ole32 -l oleaut32 -l uuid -l rpcrt4 -l advapi32 -l ws2_32 -l shlwapi
OBJS= \
obj/checkpoints.o \
obj/crypter.o \
obj/db.o \
obj/init.o \

2
src/makefile.mingw
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@ -29,6 +29,7 @@ CFLAGS=-mthreads -O2 -w -Wno-invalid-offsetof -Wformat $(DEBUGFLAGS) $(DEFS) $(I
HEADERS = \
base58.h \
bignum.h \
checkpoints.h \
crypter.h \
db.h \
headers.h \
@ -58,6 +59,7 @@ endif
LIBS += -l kernel32 -l user32 -l gdi32 -l comdlg32 -l winspool -l winmm -l shell32 -l comctl32 -l ole32 -l oleaut32 -l uuid -l rpcrt4 -l advapi32 -l ws2_32 -l shlwapi
OBJS= \
obj/checkpoints.o \
obj/crypter.o \
obj/db.o \
obj/init.o \

2
src/makefile.osx
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@ -49,6 +49,7 @@ CFLAGS=-mmacosx-version-min=10.5 -arch i386 -O3 -Wno-invalid-offsetof -Wformat $
HEADERS = \
base58.h \
bignum.h \
checkpoints.h \
crypter.h \
db.h \
headers.h \
@ -69,6 +70,7 @@ HEADERS = \
wallet.h
OBJS= \
obj/checkpoints.o \
obj/crypter.o \
obj/db.o \
obj/init.o \

2
src/makefile.unix
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@ -87,6 +87,7 @@ xCXXFLAGS=-pthread -Wno-invalid-offsetof -Wformat $(DEBUGFLAGS) $(DEFS) $(HARDEN
HEADERS = \
base58.h \
bignum.h \
checkpoints.h \
crypter.h \
db.h \
headers.h \
@ -107,6 +108,7 @@ HEADERS = \
wallet.h
OBJS= \
obj/checkpoints.o \
obj/crypter.o \
obj/db.o \
obj/init.o \

6
src/makefile.vc
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@ -43,6 +43,7 @@ CFLAGS=/MD /c /nologo /EHsc /GR /Zm300 $(DEBUGFLAGS) $(DEFS) $(INCLUDEPATHS)
HEADERS = \
base58.h \
bignum.h \
checkpoints.h \
crypter.h \
db.h \
headers.h \
@ -65,6 +66,7 @@ HEADERS = \
wallet.h
OBJS= \
obj\checkpoints.o \
obj\crypter.o \
obj\db.o \
obj\init.o \
@ -87,6 +89,8 @@ all: bitcoind.exe
.cpp{obj}.obj:
cl $(CFLAGS) /DGUI /Fo$@ %s
obj\checkpoints.obj: $(HEADERS)
obj\util.obj: $(HEADERS)
obj\script.obj: $(HEADERS)
@ -116,6 +120,8 @@ obj\uibase.obj: $(HEADERS)
.cpp{obj\nogui}.obj:
cl $(CFLAGS) /Fo$@ %s
obj\nogui\checkpoints.obj: $(HEADERS)
obj\nogui\util.obj: $(HEADERS)
obj\nogui\script.obj: $(HEADERS)

34
src/test/Checkpoints_tests.cpp Normal file
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@ -0,0 +1,34 @@
//
// Unit tests for block-chain checkpoints
//
#include <boost/assign/list_of.hpp> // for 'map_list_of()'
#include <boost/test/unit_test.hpp>
#include <boost/foreach.hpp>
#include "../checkpoints.h"
#include "../util.h"
using namespace std;
BOOST_AUTO_TEST_SUITE(Checkpoints_tests)
BOOST_AUTO_TEST_CASE(sanity)
{
uint256 p11111 = uint256("0x0000000069e244f73d78e8fd29ba2fd2ed618bd6fa2ee92559f542fdb26e7c1d");
uint256 p140700 = uint256("0x000000000000033b512028abb90e1626d8b346fd0ed598ac0a3c371138dce2bd");
BOOST_CHECK(Checkpoints::CheckBlock(11111, p11111));
BOOST_CHECK(Checkpoints::CheckBlock(140700, p140700));
// Wrong hashes at checkpoints should fail:
BOOST_CHECK(!Checkpoints::CheckBlock(11111, p140700));
BOOST_CHECK(!Checkpoints::CheckBlock(140700, p11111));
// ... but any hash not at a checkpoint should succeed:
BOOST_CHECK(Checkpoints::CheckBlock(11111+1, p140700));
BOOST_CHECK(Checkpoints::CheckBlock(140700+1, p11111));
BOOST_CHECK(Checkpoints::GetTotalBlocksEstimate() >= 140700);
}
BOOST_AUTO_TEST_SUITE_END()

50
src/test/DoS_tests.cpp
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@ -1,6 +1,7 @@
//
// Unit tests for denial-of-service detection/prevention code
//
#include <boost/assign/list_of.hpp> // for 'map_list_of()'
#include <boost/test/unit_test.hpp>
#include <boost/foreach.hpp>
@ -64,5 +65,54 @@ BOOST_AUTO_TEST_CASE(DoS_bantime)
BOOST_CHECK(!CNode::IsBanned(addr.ip));
}
static bool CheckNBits(unsigned int nbits1, int64 time1, unsigned int nbits2, int64 time2)
{
if (time1 > time2)
return CheckNBits(nbits2, time2, nbits1, time1);
int64 deltaTime = time2-time1;
CBigNum required;
required.SetCompact(ComputeMinWork(nbits1, deltaTime));
CBigNum have;
have.SetCompact(nbits2);
return (have <= required);
}
BOOST_AUTO_TEST_CASE(DoS_checknbits)
{
using namespace boost::assign; // for 'map_list_of()'
// Timestamps,nBits from the bitcoin blockchain.
// These are the block-chain checkpoint blocks
typedef std::map<int64, unsigned int> BlockData;
BlockData chainData =
map_list_of(1239852051,486604799)(1262749024,486594666)
(1279305360,469854461)(1280200847,469830746)(1281678674,469809688)
(1296207707,453179945)(1302624061,453036989)(1309640330,437004818)
(1313172719,436789733);
// Make sure CheckNBits considers every combination of block-chain-lock-in-points
// "sane":
BOOST_FOREACH(const BlockData::value_type& i, chainData)
{
BOOST_FOREACH(const BlockData::value_type& j, chainData)
{
BOOST_CHECK(CheckNBits(i.second, i.first, j.second, j.first));
}
}
// Test a couple of insane combinations:
BlockData::value_type firstcheck = *(chainData.begin());
BlockData::value_type lastcheck = *(chainData.rbegin());
// First checkpoint difficulty at or a while after the last checkpoint time should fail when
// compared to last checkpoint
BOOST_CHECK(!CheckNBits(firstcheck.second, lastcheck.first+60*10, lastcheck.second, lastcheck.first));
BOOST_CHECK(!CheckNBits(firstcheck.second, lastcheck.first+60*60*24*14, lastcheck.second, lastcheck.first));
// ... but OK if enough time passed for difficulty to adjust downward:
BOOST_CHECK(CheckNBits(firstcheck.second, lastcheck.first+60*60*24*365*4, lastcheck.second, lastcheck.first));
}
BOOST_AUTO_TEST_SUITE_END()

1
src/test/test_bitcoin.cpp
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@ -13,6 +13,7 @@
#include "util_tests.cpp"
#include "base58_tests.cpp"
#include "miner_tests.cpp"
#include "Checkpoints_tests.cpp"
CWallet* pwalletMain;