122 lines
3.8 KiB
C++
122 lines
3.8 KiB
C++
// 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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#ifndef BITCOIN_COMPRESSOR_H
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#define BITCOIN_COMPRESSOR_H
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#include "primitives/transaction.h"
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#include "script/script.h"
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#include "serialize.h"
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class CKeyID;
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class CPubKey;
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class CScriptID;
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/** Compact serializer for scripts.
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*
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* It detects common cases and encodes them much more efficiently.
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* 3 special cases are defined:
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* * Pay to pubkey hash (encoded as 21 bytes)
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* * Pay to script hash (encoded as 21 bytes)
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* * Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes)
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*
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* Other scripts up to 121 bytes require 1 byte + script length. Above
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* that, scripts up to 16505 bytes require 2 bytes + script length.
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*/
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class CScriptCompressor
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{
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private:
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/**
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* make this static for now (there are only 6 special scripts defined)
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* this can potentially be extended together with a new nVersion for
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* transactions, in which case this value becomes dependent on nVersion
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* and nHeight of the enclosing transaction.
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*/
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static const unsigned int nSpecialScripts = 6;
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CScript &script;
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protected:
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/**
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* These check for scripts for which a special case with a shorter encoding is defined.
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* They are implemented separately from the CScript test, as these test for exact byte
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* sequence correspondences, and are more strict. For example, IsToPubKey also verifies
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* whether the public key is valid (as invalid ones cannot be represented in compressed
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* form).
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*/
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bool IsToKeyID(CKeyID &hash) const;
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bool IsToScriptID(CScriptID &hash) const;
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bool IsToPubKey(CPubKey &pubkey) const;
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bool Compress(std::vector<unsigned char> &out) const;
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unsigned int GetSpecialSize(unsigned int nSize) const;
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bool Decompress(unsigned int nSize, const std::vector<unsigned char> &out);
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public:
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CScriptCompressor(CScript &scriptIn) : script(scriptIn) { }
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template<typename Stream>
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void Serialize(Stream &s) const {
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std::vector<unsigned char> compr;
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if (Compress(compr)) {
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s << CFlatData(compr);
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return;
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}
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unsigned int nSize = script.size() + nSpecialScripts;
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s << VARINT(nSize);
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s << CFlatData(script);
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}
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template<typename Stream>
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void Unserialize(Stream &s) {
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unsigned int nSize = 0;
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s >> VARINT(nSize);
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if (nSize < nSpecialScripts) {
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std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00);
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s >> REF(CFlatData(vch));
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Decompress(nSize, vch);
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return;
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}
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nSize -= nSpecialScripts;
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if (nSize > MAX_SCRIPT_SIZE) {
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// Overly long script, replace with a short invalid one
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script << OP_RETURN;
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s.ignore(nSize);
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} else {
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script.resize(nSize);
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s >> REF(CFlatData(script));
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}
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}
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};
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/** wrapper for CTxOut that provides a more compact serialization */
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class CTxOutCompressor
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{
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private:
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CTxOut &txout;
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public:
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static uint64_t CompressAmount(uint64_t nAmount);
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static uint64_t DecompressAmount(uint64_t nAmount);
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CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
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ADD_SERIALIZE_METHODS;
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template <typename Stream, typename Operation>
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inline void SerializationOp(Stream& s, Operation ser_action) {
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if (!ser_action.ForRead()) {
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uint64_t nVal = CompressAmount(txout.nValue);
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READWRITE(VARINT(nVal));
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} else {
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uint64_t nVal = 0;
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READWRITE(VARINT(nVal));
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txout.nValue = DecompressAmount(nVal);
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}
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CScriptCompressor cscript(REF(txout.scriptPubKey));
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READWRITE(cscript);
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}
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};
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#endif // BITCOIN_COMPRESSOR_H
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