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Make signature cache optional

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This commit is contained in:
Pieter Wuille 2014-09-10 16:16:09 +02:00
parent c7829ea797
commit 5c1e798a8e
9 changed files with 155 additions and 88 deletions
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2
src/Makefile.am
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@ -103,6 +103,7 @@ BITCOIN_CORE_H = \
script/compressor.h \
script/interpreter.h \
script/script.h \
script/sigcache.h \
script/sign.h \
script/standard.h \
serialize.h \
@ -218,6 +219,7 @@ libbitcoin_common_a_SOURCES = \
script/compressor.cpp \
script/interpreter.cpp \
script/script.cpp \
script/sigcache.cpp \
script/sign.cpp \
script/standard.cpp \
$(BITCOIN_CORE_H)

2
src/bitcoin-tx.cpp
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@ -435,7 +435,7 @@ static void MutateTxSign(CMutableTransaction& tx, const string& flagStr)
BOOST_FOREACH(const CTransaction& txv, txVariants) {
txin.scriptSig = CombineSignatures(prevPubKey, mergedTx, i, txin.scriptSig, txv.vin[i].scriptSig);
}
if (!VerifyScript(txin.scriptSig, prevPubKey, mergedTx, i, STANDARD_SCRIPT_VERIFY_FLAGS))
if (!VerifyScript(txin.scriptSig, prevPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, SignatureChecker(mergedTx, i)))
fComplete = false;
}

2
src/main.cpp
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@ -645,7 +645,7 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
// IsStandard() will have already returned false
// and this method isn't called.
vector<vector<unsigned char> > stack;
if (!EvalScript(stack, tx.vin[i].scriptSig, tx, i, false))
if (!EvalScript(stack, tx.vin[i].scriptSig, false, BaseSignatureChecker()))
return false;
if (whichType == TX_SCRIPTHASH)

1
src/main.h
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@ -17,6 +17,7 @@
#include "net.h"
#include "pow.h"
#include "script/script.h"
#include "script/sigcache.h"
#include "script/standard.h"
#include "sync.h"
#include "txmempool.h"

74
src/script/interpreter.cpp
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@ -9,14 +9,10 @@
#include "crypto/ripemd160.h"
#include "crypto/sha1.h"
#include "crypto/sha2.h"
#include "random.h"
#include "script/script.h"
#include "uint256.h"
#include "util.h"
#include <boost/thread.hpp>
#include <boost/tuple/tuple_comparison.hpp>
using namespace std;
typedef vector<unsigned char> valtype;
@ -132,7 +128,7 @@ bool IsCanonicalSignature(const valtype &vchSig, unsigned int flags) {
return true;
}
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const SignatureChecker& checker)
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker)
{
CScript::const_iterator pc = script.begin();
CScript::const_iterator pend = script.end();
@ -921,65 +917,13 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
return ss.GetHash();
}
// Valid signature cache, to avoid doing expensive ECDSA signature checking
// twice for every transaction (once when accepted into memory pool, and
// again when accepted into the block chain)
class CSignatureCache
bool SignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash, int flags) const
{
private:
// sigdata_type is (signature hash, signature, public key):
typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type;
std::set< sigdata_type> setValid;
boost::shared_mutex cs_sigcache;
public:
bool
Get(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
{
boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
sigdata_type k(hash, vchSig, pubKey);
std::set<sigdata_type>::iterator mi = setValid.find(k);
if (mi != setValid.end())
return true;
return false;
}
void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
{
// DoS prevention: limit cache size to less than 10MB
// (~200 bytes per cache entry times 50,000 entries)
// Since there are a maximum of 20,000 signature operations per block
// 50,000 is a reasonable default.
int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000);
if (nMaxCacheSize <= 0) return;
boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
while (static_cast<int64_t>(setValid.size()) > nMaxCacheSize)
{
// Evict a random entry. Random because that helps
// foil would-be DoS attackers who might try to pre-generate
// and re-use a set of valid signatures just-slightly-greater
// than our cache size.
uint256 randomHash = GetRandHash();
std::vector<unsigned char> unused;
std::set<sigdata_type>::iterator it =
setValid.lower_bound(sigdata_type(randomHash, unused, unused));
if (it == setValid.end())
it = setValid.begin();
setValid.erase(*it);
}
sigdata_type k(hash, vchSig, pubKey);
setValid.insert(k);
}
};
return pubkey.Verify(sighash, vchSig);
}
bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode, int flags) const
{
static CSignatureCache signatureCache;
CPubKey pubkey(vchPubKey);
if (!pubkey.IsValid())
return false;
@ -993,19 +937,13 @@ bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vec
uint256 sighash = SignatureHash(scriptCode, txTo, nIn, nHashType);
if (signatureCache.Get(sighash, vchSig, pubkey))
return true;
if (!pubkey.Verify(sighash, vchSig))
if (!VerifySignature(vchSig, pubkey, sighash, flags))
return false;
if (!(flags & SCRIPT_VERIFY_NOCACHE))
signatureCache.Set(sighash, vchSig, pubkey);
return true;
}
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const SignatureChecker& checker)
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker)
{
vector<vector<unsigned char> > stack, stackCopy;
if (!EvalScript(stack, scriptSig, flags, checker))

34
src/script/interpreter.h
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@ -10,9 +10,10 @@
#include <stdint.h>
#include <string>
class uint256;
class CPubKey;
class CScript;
class CTransaction;
class uint256;
/** Signature hash types/flags */
enum
@ -39,29 +40,32 @@ bool IsCanonicalSignature(const std::vector<unsigned char> &vchSig, unsigned int
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
class SignatureChecker
class BaseSignatureChecker
{
public:
virtual bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, int nFlags) const
{
return false;
}
virtual ~BaseSignatureChecker() {}
};
class SignatureChecker : public BaseSignatureChecker
{
private:
const CTransaction& txTo;
unsigned int nIn;
protected:
virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash, int flags) const;
public:
SignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, int nFlags) const;
};
bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const SignatureChecker& checker);
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const SignatureChecker& checker);
// Wrappers using a default SignatureChecker.
bool inline EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
{
return EvalScript(stack, script, flags, SignatureChecker(txTo, nIn));
}
bool inline VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
{
return VerifyScript(scriptSig, scriptPubKey, flags, SignatureChecker(txTo, nIn));
}
bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker);
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker);
#endif // H_BITCOIN_SCRIPT_INTERPRETER

88
src/script/sigcache.cpp Normal file
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@ -0,0 +1,88 @@
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2013 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include "sigcache.h"
#include "key.h"
#include "random.h"
#include "uint256.h"
#include "util.h"
#include <boost/thread.hpp>
#include <boost/tuple/tuple_comparison.hpp>
namespace {
// Valid signature cache, to avoid doing expensive ECDSA signature checking
// twice for every transaction (once when accepted into memory pool, and
// again when accepted into the block chain)
class CSignatureCache
{
private:
// sigdata_type is (signature hash, signature, public key):
typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type;
std::set< sigdata_type> setValid;
boost::shared_mutex cs_sigcache;
public:
bool
Get(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
{
boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
sigdata_type k(hash, vchSig, pubKey);
std::set<sigdata_type>::iterator mi = setValid.find(k);
if (mi != setValid.end())
return true;
return false;
}
void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
{
// DoS prevention: limit cache size to less than 10MB
// (~200 bytes per cache entry times 50,000 entries)
// Since there are a maximum of 20,000 signature operations per block
// 50,000 is a reasonable default.
int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000);
if (nMaxCacheSize <= 0) return;
boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
while (static_cast<int64_t>(setValid.size()) > nMaxCacheSize)
{
// Evict a random entry. Random because that helps
// foil would-be DoS attackers who might try to pre-generate
// and re-use a set of valid signatures just-slightly-greater
// than our cache size.
uint256 randomHash = GetRandHash();
std::vector<unsigned char> unused;
std::set<sigdata_type>::iterator it =
setValid.lower_bound(sigdata_type(randomHash, unused, unused));
if (it == setValid.end())
it = setValid.begin();
setValid.erase(*it);
}
sigdata_type k(hash, vchSig, pubKey);
setValid.insert(k);
}
};
}
bool CachingSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash, int flags) const
{
static CSignatureCache signatureCache;
if (signatureCache.Get(sighash, vchSig, pubkey))
return true;
if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash, flags))
return false;
if (!(flags & SCRIPT_VERIFY_NOCACHE))
signatureCache.Set(sighash, vchSig, pubkey);
return true;
}

34
src/script/sigcache.h Normal file
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@ -0,0 +1,34 @@
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2013 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef H_BITCOIN_SCRIPT_SIGCACHE
#define H_BITCOIN_SCRIPT_SIGCACHE
#include "script/interpreter.h"
#include <vector>
class CPubKey;
class CachingSignatureChecker : public SignatureChecker
{
public:
CachingSignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : SignatureChecker(txToIn, nInIn) {}
bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash, int flags) const;
};
// Wrappers using a default SignatureChecker.
bool inline EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
{
return EvalScript(stack, script, flags, CachingSignatureChecker(txTo, nIn));
}
bool inline VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
{
return VerifyScript(scriptSig, scriptPubKey, flags, CachingSignatureChecker(txTo, nIn));
}
#endif

6
src/script/sign.cpp
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@ -123,7 +123,7 @@ bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutabl
}
// Test solution
return VerifyScript(txin.scriptSig, fromPubKey, txTo, nIn, STANDARD_SCRIPT_VERIFY_FLAGS);
return VerifyScript(txin.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, SignatureChecker(txTo, nIn));
}
bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
@ -252,9 +252,9 @@ CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo, unsign
Solver(scriptPubKey, txType, vSolutions);
vector<valtype> stack1;
EvalScript(stack1, scriptSig1, CTransaction(), 0, SCRIPT_VERIFY_STRICTENC);
EvalScript(stack1, scriptSig1, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker());
vector<valtype> stack2;
EvalScript(stack2, scriptSig2, CTransaction(), 0, SCRIPT_VERIFY_STRICTENC);
EvalScript(stack2, scriptSig2, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker());
return CombineSignatures(scriptPubKey, txTo, nIn, txType, vSolutions, stack1, stack2);
}