compressor.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_COMPRESSOR_H
#define BITCOIN_COMPRESSOR_H
 
#include "primitives/transaction.h"
#include "script/script.h"
#include "serialize.h"
 
class CKeyID;
class CPubKey;
class CScriptID;
 
class CScriptCompressor
{
private:
    static const unsigned int nSpecialScripts = 6;
 
    CScript& script;
 
protected:
    bool IsToKeyID(CKeyID& hash) const;
    bool IsToScriptID(CScriptID& hash) const;
    bool IsToPubKey(CPubKey& pubkey) const;
 
    bool Compress(std::vector<unsigned char>& out) const;
    unsigned int GetSpecialSize(unsigned int nSize) const;
    bool Decompress(unsigned int nSize, const std::vector<unsigned char>& out);
 
public:
    CScriptCompressor(CScript& scriptIn) : script(scriptIn) {}
 
    unsigned int GetSerializeSize(int nType, int nVersion) const
    {
        std::vector<unsigned char> compr;
        if (Compress(compr))
            return compr.size();
        unsigned int nSize = script.size() + nSpecialScripts;
        return script.size() + VARINT(nSize).GetSerializeSize(nType, nVersion);
    }
 
    template <typename Stream>
    void Serialize(Stream& s, int nType, int nVersion) const
    {
        std::vector<unsigned char> compr;
        if (Compress(compr)) {
            s << CFlatData(compr);
            return;
        }
        unsigned int nSize = script.size() + nSpecialScripts;
        s << VARINT(nSize);
        s << CFlatData(script);
    }
 
    template <typename Stream>
    void Unserialize(Stream& s, int nType, int nVersion)
    {
        unsigned int nSize = 0;
        s >> VARINT(nSize);
        if (nSize < nSpecialScripts) {
            std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00);
            s >> REF(CFlatData(vch));
            Decompress(nSize, vch);
            return;
        }
        nSize -= nSpecialScripts;
        if (nSize > MAX_SCRIPT_SIZE) {
        s >> REF(CFlatData(script));                // Overly long script, replace with a short invalid one
            script << OP_RETURN;
            s.ignore(nSize);
        } else {
            script.resize(nSize);
            s >> REF(CFlatData(script));
        }
    }
};
 
class CTxOutCompressor
{
private:
    CTxOut& txout;
 
public:
    static uint64_t CompressAmount(uint64_t nAmount);
    static uint64_t DecompressAmount(uint64_t nAmount);
 
    CTxOutCompressor(CTxOut& txoutIn) : txout(txoutIn) {}
 
    ADD_SERIALIZE_METHODS;
 
    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion)
    {
        if (!ser_action.ForRead()) {
            uint64_t nVal = CompressAmount(txout.nValue);
            READWRITE(VARINT(nVal));
        } else {
            uint64_t nVal = 0;
            READWRITE(VARINT(nVal));
            txout.nValue = DecompressAmount(nVal);
        }
        CScriptCompressor cscript(REF(txout.scriptPubKey));
        READWRITE(cscript);
    }
};
 
#endif // BITCOIN_COMPRESSOR_H