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121 lines
3.8 KiB
121 lines
3.8 KiB
// 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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