Pieter Wuille
10 years ago
9 changed files with 155 additions and 88 deletions
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "sigcache.h" |
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#include "key.h" |
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#include "random.h" |
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#include "uint256.h" |
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#include "util.h" |
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#include <boost/thread.hpp> |
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#include <boost/tuple/tuple_comparison.hpp> |
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namespace { |
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// Valid signature cache, to avoid doing expensive ECDSA signature checking
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// twice for every transaction (once when accepted into memory pool, and
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// again when accepted into the block chain)
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class CSignatureCache |
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{ |
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private: |
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// sigdata_type is (signature hash, signature, public key):
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typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type; |
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std::set< sigdata_type> setValid; |
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boost::shared_mutex cs_sigcache; |
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public: |
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bool |
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Get(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey) |
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{ |
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boost::shared_lock<boost::shared_mutex> lock(cs_sigcache); |
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sigdata_type k(hash, vchSig, pubKey); |
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std::set<sigdata_type>::iterator mi = setValid.find(k); |
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if (mi != setValid.end()) |
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return true; |
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return false; |
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} |
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void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey) |
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{ |
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// DoS prevention: limit cache size to less than 10MB
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// (~200 bytes per cache entry times 50,000 entries)
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// Since there are a maximum of 20,000 signature operations per block
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// 50,000 is a reasonable default.
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int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000); |
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if (nMaxCacheSize <= 0) return; |
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boost::unique_lock<boost::shared_mutex> lock(cs_sigcache); |
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while (static_cast<int64_t>(setValid.size()) > nMaxCacheSize) |
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{ |
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// Evict a random entry. Random because that helps
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// foil would-be DoS attackers who might try to pre-generate
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// and re-use a set of valid signatures just-slightly-greater
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// than our cache size.
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uint256 randomHash = GetRandHash(); |
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std::vector<unsigned char> unused; |
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std::set<sigdata_type>::iterator it = |
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setValid.lower_bound(sigdata_type(randomHash, unused, unused)); |
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if (it == setValid.end()) |
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it = setValid.begin(); |
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setValid.erase(*it); |
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} |
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sigdata_type k(hash, vchSig, pubKey); |
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setValid.insert(k); |
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} |
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}; |
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} |
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bool CachingSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash, int flags) const |
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{ |
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static CSignatureCache signatureCache; |
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if (signatureCache.Get(sighash, vchSig, pubkey)) |
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return true; |
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if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash, flags)) |
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return false; |
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if (!(flags & SCRIPT_VERIFY_NOCACHE)) |
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signatureCache.Set(sighash, vchSig, pubkey); |
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return true; |
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} |
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@ -0,0 +1,34 @@ |
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef H_BITCOIN_SCRIPT_SIGCACHE |
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#define H_BITCOIN_SCRIPT_SIGCACHE |
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#include "script/interpreter.h" |
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#include <vector> |
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class CPubKey; |
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class CachingSignatureChecker : public SignatureChecker |
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{ |
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public: |
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CachingSignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : SignatureChecker(txToIn, nInIn) {} |
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bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash, int flags) const; |
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}; |
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// Wrappers using a default SignatureChecker.
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bool inline EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags) |
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{ |
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return EvalScript(stack, script, flags, CachingSignatureChecker(txTo, nIn)); |
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} |
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bool inline VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, unsigned int flags) |
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{ |
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return VerifyScript(scriptSig, scriptPubKey, flags, CachingSignatureChecker(txTo, nIn)); |
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} |
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#endif |
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