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208 lines
7.4 KiB
208 lines
7.4 KiB
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2018 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_MERKLEBLOCK_H
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#define BITCOIN_MERKLEBLOCK_H
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#include <serialize.h>
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#include <uint256.h>
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#include <primitives/block.h>
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#include <bloom.h>
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#include <vector>
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// Helper functions for serialization.
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std::vector<unsigned char> BitsToBytes(const std::vector<bool>& bits);
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std::vector<bool> BytesToBits(const std::vector<unsigned char>& bytes);
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/** Data structure that represents a partial merkle tree.
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*
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* It represents a subset of the txid's of a known block, in a way that
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* allows recovery of the list of txid's and the merkle root, in an
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* authenticated way.
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*
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* The encoding works as follows: we traverse the tree in depth-first order,
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* storing a bit for each traversed node, signifying whether the node is the
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* parent of at least one matched leaf txid (or a matched txid itself). In
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* case we are at the leaf level, or this bit is 0, its merkle node hash is
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* stored, and its children are not explored further. Otherwise, no hash is
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* stored, but we recurse into both (or the only) child branch. During
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* decoding, the same depth-first traversal is performed, consuming bits and
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* hashes as they written during encoding.
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*
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* The serialization is fixed and provides a hard guarantee about the
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* encoded size:
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*
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* SIZE <= 10 + ceil(32.25*N)
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*
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* Where N represents the number of leaf nodes of the partial tree. N itself
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* is bounded by:
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*
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* N <= total_transactions
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* N <= 1 + matched_transactions*tree_height
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*
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* The serialization format:
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* - uint32 total_transactions (4 bytes)
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* - varint number of hashes (1-3 bytes)
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* - uint256[] hashes in depth-first order (<= 32*N bytes)
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* - varint number of bytes of flag bits (1-3 bytes)
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* - byte[] flag bits, packed per 8 in a byte, least significant bit first (<= 2*N-1 bits)
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* The size constraints follow from this.
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*/
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class CPartialMerkleTree
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{
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protected:
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/** the total number of transactions in the block */
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unsigned int nTransactions;
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/** node-is-parent-of-matched-txid bits */
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std::vector<bool> vBits;
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/** txids and internal hashes */
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std::vector<uint256> vHash;
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/** flag set when encountering invalid data */
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bool fBad;
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/** helper function to efficiently calculate the number of nodes at given height in the merkle tree */
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unsigned int CalcTreeWidth(int height) const {
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return (nTransactions+(1 << height)-1) >> height;
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}
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/** calculate the hash of a node in the merkle tree (at leaf level: the txid's themselves) */
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uint256 CalcHash(int height, unsigned int pos, const std::vector<uint256> &vTxid);
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/** recursive function that traverses tree nodes, storing the data as bits and hashes */
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void TraverseAndBuild(int height, unsigned int pos, const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);
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/**
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* recursive function that traverses tree nodes, consuming the bits and hashes produced by TraverseAndBuild.
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* it returns the hash of the respective node and its respective index.
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*/
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uint256 TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex);
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public:
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SERIALIZE_METHODS(CPartialMerkleTree, obj)
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{
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READWRITE(obj.nTransactions, obj.vHash);
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std::vector<unsigned char> bytes;
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SER_WRITE(obj, bytes = BitsToBytes(obj.vBits));
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READWRITE(bytes);
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SER_READ(obj, obj.vBits = BytesToBits(bytes));
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SER_READ(obj, obj.fBad = false);
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}
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/** Construct a partial merkle tree from a list of transaction ids, and a mask that selects a subset of them */
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CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);
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CPartialMerkleTree();
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/**
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* extract the matching txid's represented by this partial merkle tree
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* and their respective indices within the partial tree.
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* returns the merkle root, or 0 in case of failure
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*/
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uint256 ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex);
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/** Get number of transactions the merkle proof is indicating for cross-reference with
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* local blockchain knowledge.
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*/
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unsigned int GetNumTransactions() const { return nTransactions; };
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};
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/**
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* Used to relay blocks as header + vector<merkle branch>
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* to filtered nodes.
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*
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* NOTE: The class assumes that the given CBlock has *at least* 1 transaction. If the CBlock has 0 txs, it will hit an assertion.
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*/
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class CMerkleBlock
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{
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public:
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/** Public only for unit testing */
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CBlockHeader header;
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CPartialMerkleTree txn;
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/**
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* Public only for unit testing and relay testing (not relayed).
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*
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* Used only when a bloom filter is specified to allow
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* testing the transactions which matched the bloom filter.
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*/
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std::vector<std::pair<unsigned int, uint256> > vMatchedTxn;
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/**
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* Create from a CBlock, filtering transactions according to filter
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* Note that this will call IsRelevantAndUpdate on the filter for each transaction,
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* thus the filter will likely be modified.
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*/
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CMerkleBlock(const CBlock& block, CBloomFilter& filter) : CMerkleBlock(block, &filter, nullptr) { }
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// Create from a CBlock, matching the txids in the set
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CMerkleBlock(const CBlock& block, const std::set<uint256>& txids) : CMerkleBlock(block, nullptr, &txids) { }
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CMerkleBlock() {}
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SERIALIZE_METHODS(CMerkleBlock, obj) { READWRITE(obj.header, obj.txn); }
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private:
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// Combined constructor to consolidate code
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CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids);
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};
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/**
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* Can be requested by MWEB light clients to retrieve and verify MWEB headers.
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*
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* Serializes as merkleblock + tx (HogEx) + MWEB header:
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*
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* Merkle Block
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* - uint32 version (4 bytes)
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* - uint256 prev_block (32 bytes)
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* - uint256 merkle_root (32 bytes)
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* - uint32 timestamp (4 bytes)
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* - uint32 bits (4 bytes)
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* - uint32 nonce (4 bytes)
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* - uint32 total_transactions (4 bytes)
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* - varint number of hashes (1-3 bytes)
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* - uint256[] hashes in depth-first order (<= 32*N bytes)
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* - varint number of bytes of flag bits (1-3 bytes)
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* - byte[] flag bits, packed per 8 in a byte, least significant bit first (<= 2*N-1 bits)
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*
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* HogEx Transaction
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* - CTransaction hogex transaction (? bytes)
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*
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* MWEB Header
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* - int32 height (4 bytes)
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* - uint256 output_root (32 bytes)
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* - uint256 kernel_root (32 bytes)
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* - uint256 leafset_root (32 bytes)
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* - uint256 kernel_offset (32 bytes)
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* - uint256 stealth_offset (32 bytes)
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* - uint64 output_mmr_size (8 bytes)
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* - uint64 kernel_mmr_size (8 bytes)
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*
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* NOTE: The class assumes that the given CBlock contains a hogex transaction and MWEB block data.
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* If it does not, an assertion will be hit.
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*/
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class CMerkleBlockWithMWEB
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{
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private:
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CMerkleBlock merkle;
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CTransactionRef hogex;
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mw::Header::CPtr mweb_header;
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public:
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CMerkleBlockWithMWEB() { }
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CMerkleBlockWithMWEB(const CBlock& block);
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SERIALIZE_METHODS(CMerkleBlockWithMWEB, obj) { READWRITE(obj.merkle, obj.hogex, obj.mweb_header); }
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};
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#endif // BITCOIN_MERKLEBLOCK_H
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