sigcache.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_SCRIPT_SIGCACHE_H
#define BITCOIN_SCRIPT_SIGCACHE_H

#include <script/interpreter.h>

#include <vector>

// DoS prevention: limit cache size to 32MB (over 1000000 entries on 64-bit
// systems). Due to how we count cache size, actual memory usage is slightly
// more (~32.25 MB)
static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 32;
// Maximum sig cache size allowed
static const int64_t MAX_MAX_SIG_CACHE_SIZE = 16384;

class CPubKey;

class SignatureCacheHasher {
public:
    template <uint8_t hash_select>
    uint32_t operator()(const uint256 &key) const {
        static_assert(hash_select < 8,
                      "SignatureCacheHasher only has 8 hashes available.");
        uint32_t u;
        std::memcpy(&u, key.begin() + 4 * hash_select, 4);
        return u;
    }
};

class CachingTransactionSignatureChecker : public TransactionSignatureChecker {
private:
    bool store;

    bool IsCached(const std::vector<uint8_t> &vchSig, const CPubKey &vchPubKey,
                  const uint256 &sighash) const;

public:
    CachingTransactionSignatureChecker(const CTransaction *txToIn,
                                       unsigned int nInIn,
                                       const Amount amountIn, bool storeIn,
                                       PrecomputedTransactionData &txdataIn)
        : TransactionSignatureChecker(txToIn, nInIn, amountIn, txdataIn),
          store(storeIn) {}

    bool VerifySignature(const std::vector<uint8_t> &vchSig,
                         const CPubKey &vchPubKey,
                         const uint256 &sighash) const override;

    friend class TestCachingTransactionSignatureChecker;
};

void InitSignatureCache();

#endif // BITCOIN_SCRIPT_SIGCACHE_H