LCOV - code coverage report
Current view: top level - src - merkleblock.h (source / functions) Hit Total Coverage
Test: fuzz_coverage.info Lines: 0 16 0.0 %
Date: 2023-10-05 12:38:51 Functions: 0 49 0.0 %
Branches: 0 16 0.0 %

           Branch data     Line data    Source code
       1                 :            : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2                 :            : // Copyright (c) 2009-2021 The Bitcoin Core developers
       3                 :            : // Distributed under the MIT software license, see the accompanying
       4                 :            : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       5                 :            : 
       6                 :            : #ifndef BITCOIN_MERKLEBLOCK_H
       7                 :            : #define BITCOIN_MERKLEBLOCK_H
       8                 :            : 
       9                 :            : #include <common/bloom.h>
      10                 :            : #include <primitives/block.h>
      11                 :            : #include <serialize.h>
      12                 :            : #include <uint256.h>
      13                 :            : 
      14                 :            : #include <vector>
      15                 :            : 
      16                 :            : // Helper functions for serialization.
      17                 :            : std::vector<unsigned char> BitsToBytes(const std::vector<bool>& bits);
      18                 :            : std::vector<bool> BytesToBits(const std::vector<unsigned char>& bytes);
      19                 :            : 
      20                 :            : /** Data structure that represents a partial merkle tree.
      21                 :            :  *
      22                 :            :  * It represents a subset of the txid's of a known block, in a way that
      23                 :            :  * allows recovery of the list of txid's and the merkle root, in an
      24                 :            :  * authenticated way.
      25                 :            :  *
      26                 :            :  * The encoding works as follows: we traverse the tree in depth-first order,
      27                 :            :  * storing a bit for each traversed node, signifying whether the node is the
      28                 :            :  * parent of at least one matched leaf txid (or a matched txid itself). In
      29                 :            :  * case we are at the leaf level, or this bit is 0, its merkle node hash is
      30                 :            :  * stored, and its children are not explored further. Otherwise, no hash is
      31                 :            :  * stored, but we recurse into both (or the only) child branch. During
      32                 :            :  * decoding, the same depth-first traversal is performed, consuming bits and
      33                 :            :  * hashes as they written during encoding.
      34                 :            :  *
      35                 :            :  * The serialization is fixed and provides a hard guarantee about the
      36                 :            :  * encoded size:
      37                 :            :  *
      38                 :            :  *   SIZE <= 10 + ceil(32.25*N)
      39                 :            :  *
      40                 :            :  * Where N represents the number of leaf nodes of the partial tree. N itself
      41                 :            :  * is bounded by:
      42                 :            :  *
      43                 :            :  *   N <= total_transactions
      44                 :            :  *   N <= 1 + matched_transactions*tree_height
      45                 :            :  *
      46                 :            :  * The serialization format:
      47                 :            :  *  - uint32     total_transactions (4 bytes)
      48                 :            :  *  - varint     number of hashes   (1-3 bytes)
      49                 :            :  *  - uint256[]  hashes in depth-first order (<= 32*N bytes)
      50                 :            :  *  - varint     number of bytes of flag bits (1-3 bytes)
      51                 :            :  *  - byte[]     flag bits, packed per 8 in a byte, least significant bit first (<= 2*N-1 bits)
      52                 :            :  * The size constraints follow from this.
      53                 :            :  */
      54                 :          0 : class CPartialMerkleTree
      55                 :            : {
      56                 :            : protected:
      57                 :            :     /** the total number of transactions in the block */
      58                 :            :     unsigned int nTransactions;
      59                 :            : 
      60                 :            :     /** node-is-parent-of-matched-txid bits */
      61                 :            :     std::vector<bool> vBits;
      62                 :            : 
      63                 :            :     /** txids and internal hashes */
      64                 :            :     std::vector<uint256> vHash;
      65                 :            : 
      66                 :            :     /** flag set when encountering invalid data */
      67                 :            :     bool fBad;
      68                 :            : 
      69                 :            :     /** helper function to efficiently calculate the number of nodes at given height in the merkle tree */
      70                 :          0 :     unsigned int CalcTreeWidth(int height) const {
      71                 :          0 :         return (nTransactions+(1 << height)-1) >> height;
      72                 :            :     }
      73                 :            : 
      74                 :            :     /** calculate the hash of a node in the merkle tree (at leaf level: the txid's themselves) */
      75                 :            :     uint256 CalcHash(int height, unsigned int pos, const std::vector<uint256> &vTxid);
      76                 :            : 
      77                 :            :     /** recursive function that traverses tree nodes, storing the data as bits and hashes */
      78                 :            :     void TraverseAndBuild(int height, unsigned int pos, const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);
      79                 :            : 
      80                 :            :     /**
      81                 :            :      * recursive function that traverses tree nodes, consuming the bits and hashes produced by TraverseAndBuild.
      82                 :            :      * it returns the hash of the respective node and its respective index.
      83                 :            :      */
      84                 :            :     uint256 TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex);
      85                 :            : 
      86                 :            : public:
      87                 :            : 
      88                 :          0 :     SERIALIZE_METHODS(CPartialMerkleTree, obj)
      89                 :            :     {
      90                 :          0 :         READWRITE(obj.nTransactions, obj.vHash);
      91                 :          0 :         std::vector<unsigned char> bytes;
      92   [ #  #  #  # ]:          0 :         SER_WRITE(obj, bytes = BitsToBytes(obj.vBits));
      93   [ #  #  #  # ]:          0 :         READWRITE(bytes);
      94   [ #  #  #  # ]:          0 :         SER_READ(obj, obj.vBits = BytesToBits(bytes));
      95   [ #  #  #  # ]:          0 :         SER_READ(obj, obj.fBad = false);
      96                 :          0 :     }
      97                 :            : 
      98                 :            :     /** Construct a partial merkle tree from a list of transaction ids, and a mask that selects a subset of them */
      99                 :            :     CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch);
     100                 :            : 
     101                 :            :     CPartialMerkleTree();
     102                 :            : 
     103                 :            :     /**
     104                 :            :      * extract the matching txid's represented by this partial merkle tree
     105                 :            :      * and their respective indices within the partial tree.
     106                 :            :      * returns the merkle root, or 0 in case of failure
     107                 :            :      */
     108                 :            :     uint256 ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex);
     109                 :            : 
     110                 :            :     /** Get number of transactions the merkle proof is indicating for cross-reference with
     111                 :            :      * local blockchain knowledge.
     112                 :            :      */
     113                 :          0 :     unsigned int GetNumTransactions() const { return nTransactions; };
     114                 :            : 
     115                 :            : };
     116                 :            : 
     117                 :            : 
     118                 :            : /**
     119                 :            :  * Used to relay blocks as header + vector<merkle branch>
     120                 :            :  * to filtered nodes.
     121                 :            :  *
     122                 :            :  * NOTE: The class assumes that the given CBlock has *at least* 1 transaction. If the CBlock has 0 txs, it will hit an assertion.
     123                 :            :  */
     124                 :            : class CMerkleBlock
     125                 :            : {
     126                 :            : public:
     127                 :            :     /** Public only for unit testing */
     128                 :            :     CBlockHeader header;
     129                 :            :     CPartialMerkleTree txn;
     130                 :            : 
     131                 :            :     /**
     132                 :            :      * Public only for unit testing and relay testing (not relayed).
     133                 :            :      *
     134                 :            :      * Used only when a bloom filter is specified to allow
     135                 :            :      * testing the transactions which matched the bloom filter.
     136                 :            :      */
     137                 :            :     std::vector<std::pair<unsigned int, uint256> > vMatchedTxn;
     138                 :            : 
     139                 :            :     /**
     140                 :            :      * Create from a CBlock, filtering transactions according to filter
     141                 :            :      * Note that this will call IsRelevantAndUpdate on the filter for each transaction,
     142                 :            :      * thus the filter will likely be modified.
     143                 :            :      */
     144                 :          0 :     CMerkleBlock(const CBlock& block, CBloomFilter& filter) : CMerkleBlock(block, &filter, nullptr) { }
     145                 :            : 
     146                 :            :     // Create from a CBlock, matching the txids in the set
     147                 :          0 :     CMerkleBlock(const CBlock& block, const std::set<uint256>& txids) : CMerkleBlock(block, nullptr, &txids) { }
     148                 :            : 
     149                 :          0 :     CMerkleBlock() {}
     150                 :            : 
     151                 :          0 :     SERIALIZE_METHODS(CMerkleBlock, obj) { READWRITE(obj.header, obj.txn); }
     152                 :            : 
     153                 :            : private:
     154                 :            :     // Combined constructor to consolidate code
     155                 :            :     CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids);
     156                 :            : };
     157                 :            : 
     158                 :            : #endif // BITCOIN_MERKLEBLOCK_H

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