172f5fa738
Currently, the READWRITE macro cannot be passed any non-const temporaries, as the SerReadWrite function only accepts lvalue references. Deserializing into a temporary is very common, however. See for example things like 's >> VARINT(n)'. The VARINT macro produces a temporary wrapper that holds a reference to n. Fix this by accepting non-const rvalue references instead of lvalue references. We don't propagate the rvalue-ness down, as there are no useful optimizations that only apply to temporaries. Then use this new functionality to get rid of many (but not all) uses of the 'REF' macro (which casts away constness).
122 lines
3.9 KiB
C++
122 lines
3.9 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2017 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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explicit 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 >> 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 >> 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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explicit 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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