diff options
Diffstat (limited to 'src/script/sigcache.cpp')
-rw-r--r-- | src/script/sigcache.cpp | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp new file mode 100644 index 0000000000..981563b7ae --- /dev/null +++ b/src/script/sigcache.cpp @@ -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) const +{ + static CSignatureCache signatureCache; + + if (signatureCache.Get(sighash, vchSig, pubkey)) + return true; + + if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash)) + return false; + + if (store) + signatureCache.Set(sighash, vchSig, pubkey); + return true; +} |