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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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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))