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94 lines
3.2 KiB
94 lines
3.2 KiB
// Copyright (c) 2009-2010 Satoshi Nakamoto |
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// Copyright (c) 2009-2016 The Bitcoin Core developers |
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// Distributed under the MIT 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 "memusage.h" |
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#include "pubkey.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 "cuckoocache.h" |
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#include <boost/thread.hpp> |
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namespace { |
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/** |
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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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*/ |
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class CSignatureCache |
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{ |
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private: |
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//! Entries are SHA256(nonce || signature hash || public key || signature): |
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uint256 nonce; |
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typedef CuckooCache::cache<uint256, SignatureCacheHasher> map_type; |
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map_type setValid; |
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boost::shared_mutex cs_sigcache; |
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public: |
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CSignatureCache() |
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{ |
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GetRandBytes(nonce.begin(), 32); |
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} |
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void |
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ComputeEntry(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey) |
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{ |
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CSHA256().Write(nonce.begin(), 32).Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin()); |
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} |
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bool |
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Get(const uint256& entry, const bool erase) |
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{ |
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boost::shared_lock<boost::shared_mutex> lock(cs_sigcache); |
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return setValid.contains(entry, erase); |
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} |
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void Set(uint256& entry) |
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{ |
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boost::unique_lock<boost::shared_mutex> lock(cs_sigcache); |
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setValid.insert(entry); |
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} |
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uint32_t setup_bytes(size_t n) |
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{ |
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return setValid.setup_bytes(n); |
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} |
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}; |
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/* In previous versions of this code, signatureCache was a local static variable |
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* in CachingTransactionSignatureChecker::VerifySignature. We initialize |
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* signatureCache outside of VerifySignature to avoid the atomic operation per |
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* call overhead associated with local static variables even though |
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* signatureCache could be made local to VerifySignature. |
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*/ |
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static CSignatureCache signatureCache; |
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} // namespace |
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// To be called once in AppInitMain/BasicTestingSetup to initialize the |
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// signatureCache. |
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void InitSignatureCache() |
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{ |
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// nMaxCacheSize is unsigned. If -maxsigcachesize is set to zero, |
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// setup_bytes creates the minimum possible cache (2 elements). |
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size_t nMaxCacheSize = std::min(std::max((int64_t)0, gArgs.GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) / 2), MAX_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20); |
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size_t nElems = signatureCache.setup_bytes(nMaxCacheSize); |
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LogPrintf("Using %zu MiB out of %zu/2 requested for signature cache, able to store %zu elements\n", |
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(nElems*sizeof(uint256)) >>20, (nMaxCacheSize*2)>>20, nElems); |
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} |
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bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const |
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{ |
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uint256 entry; |
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signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey); |
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if (signatureCache.Get(entry, !store)) |
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return true; |
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if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash)) |
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return false; |
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if (store) |
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signatureCache.Set(entry); |
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return true; |
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}
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