124 lines
4.0 KiB
C++
124 lines
4.0 KiB
C++
// 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;
|
|
|
|
/** Compact serializer for scripts.
|
|
*
|
|
* It detects common cases and encodes them much more efficiently.
|
|
* 3 special cases are defined:
|
|
* * Pay to pubkey hash (encoded as 21 bytes)
|
|
* * Pay to script hash (encoded as 21 bytes)
|
|
* * Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes)
|
|
*
|
|
* Other scripts up to 121 bytes require 1 byte + script length. Above
|
|
* that, scripts up to 16505 bytes require 2 bytes + script length.
|
|
*/
|
|
class CScriptCompressor
|
|
{
|
|
private:
|
|
/**
|
|
* make this static for now (there are only 6 special scripts defined)
|
|
* this can potentially be extended together with a new nVersion for
|
|
* transactions, in which case this value becomes dependent on nVersion
|
|
* and nHeight of the enclosing transaction.
|
|
*/
|
|
static const unsigned int nSpecialScripts = 6;
|
|
|
|
CScript &script;
|
|
protected:
|
|
/**
|
|
* These check for scripts for which a special case with a shorter encoding is defined.
|
|
* They are implemented separately from the CScript test, as these test for exact byte
|
|
* sequence correspondences, and are more strict. For example, IsToPubKey also verifies
|
|
* whether the public key is valid (as invalid ones cannot be represented in compressed
|
|
* form).
|
|
*/
|
|
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;
|
|
script.resize(nSize);
|
|
s >> REF(CFlatData(script));
|
|
}
|
|
};
|
|
|
|
/** wrapper for CTxOut that provides a more compact serialization */
|
|
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
|