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# 1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
# 2 : : // Copyright (c) 2009-2020 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 : : #include <merkleblock.h>
# 7 : :
# 8 : : #include <hash.h>
# 9 : : #include <consensus/consensus.h>
# 10 : :
# 11 : :
# 12 : : std::vector<unsigned char> BitsToBytes(const std::vector<bool>& bits)
# 13 : 357 : {
# 14 : 357 : std::vector<unsigned char> ret((bits.size() + 7) / 8);
# 15 [ + + ]: 153345 : for (unsigned int p = 0; p < bits.size(); p++) {
# 16 : 152988 : ret[p / 8] |= bits[p] << (p % 8);
# 17 : 152988 : }
# 18 : 357 : return ret;
# 19 : 357 : }
# 20 : :
# 21 : : std::vector<bool> BytesToBits(const std::vector<unsigned char>& bytes)
# 22 : 361 : {
# 23 : 361 : std::vector<bool> ret(bytes.size() * 8);
# 24 [ + + ]: 154833 : for (unsigned int p = 0; p < ret.size(); p++) {
# 25 : 154472 : ret[p] = (bytes[p / 8] & (1 << (p % 8))) != 0;
# 26 : 154472 : }
# 27 : 361 : return ret;
# 28 : 361 : }
# 29 : :
# 30 : : CMerkleBlock::CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids)
# 31 : 45 : {
# 32 : 45 : header = block.GetBlockHeader();
# 33 : :
# 34 : 45 : std::vector<bool> vMatch;
# 35 : 45 : std::vector<uint256> vHashes;
# 36 : :
# 37 : 45 : vMatch.reserve(block.vtx.size());
# 38 : 45 : vHashes.reserve(block.vtx.size());
# 39 : :
# 40 [ + + ]: 250 : for (unsigned int i = 0; i < block.vtx.size(); i++)
# 41 : 205 : {
# 42 : 205 : const uint256& hash = block.vtx[i]->GetHash();
# 43 [ + + ][ + + ]: 205 : if (txids && txids->count(hash)) {
# 44 : 24 : vMatch.push_back(true);
# 45 [ + + ][ + + ]: 181 : } else if (filter && filter->IsRelevantAndUpdate(*block.vtx[i])) {
# 46 : 42 : vMatch.push_back(true);
# 47 : 42 : vMatchedTxn.emplace_back(i, hash);
# 48 : 139 : } else {
# 49 : 139 : vMatch.push_back(false);
# 50 : 139 : }
# 51 : 205 : vHashes.push_back(hash);
# 52 : 205 : }
# 53 : :
# 54 : 45 : txn = CPartialMerkleTree(vHashes, vMatch);
# 55 : 45 : }
# 56 : :
# 57 : 287595 : uint256 CPartialMerkleTree::CalcHash(int height, unsigned int pos, const std::vector<uint256> &vTxid) {
# 58 : : //we can never have zero txs in a merkle block, we always need the coinbase tx
# 59 : : //if we do not have this assert, we can hit a memory access violation when indexing into vTxid
# 60 : 287595 : assert(vTxid.size() != 0);
# 61 [ + + ]: 287595 : if (height == 0) {
# 62 : : // hash at height 0 is the txids themselves
# 63 : 181893 : return vTxid[pos];
# 64 : 181893 : } else {
# 65 : : // calculate left hash
# 66 : 105702 : uint256 left = CalcHash(height-1, pos*2, vTxid), right;
# 67 : : // calculate right hash if not beyond the end of the array - copy left hash otherwise
# 68 [ + + ]: 105702 : if (pos*2+1 < CalcTreeWidth(height-1))
# 69 : 105258 : right = CalcHash(height-1, pos*2+1, vTxid);
# 70 : 444 : else
# 71 : 444 : right = left;
# 72 : : // combine subhashes
# 73 : 105702 : return Hash(left, right);
# 74 : 105702 : }
# 75 : 287595 : }
# 76 : :
# 77 : 153186 : void CPartialMerkleTree::TraverseAndBuild(int height, unsigned int pos, const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch) {
# 78 : : // determine whether this node is the parent of at least one matched txid
# 79 : 153186 : bool fParentOfMatch = false;
# 80 [ + + ][ + + ]: 1883543 : for (unsigned int p = pos << height; p < (pos+1) << height && p < nTransactions; p++)
# 81 : 1730357 : fParentOfMatch |= vMatch[p];
# 82 : : // store as flag bit
# 83 : 153186 : vBits.push_back(fParentOfMatch);
# 84 [ + + ][ + + ]: 153186 : if (height==0 || !fParentOfMatch) {
# 85 : : // if at height 0, or nothing interesting below, store hash and stop
# 86 : 76635 : vHash.push_back(CalcHash(height, pos, vTxid));
# 87 : 76635 : } else {
# 88 : : // otherwise, don't store any hash, but descend into the subtrees
# 89 : 76551 : TraverseAndBuild(height-1, pos*2, vTxid, vMatch);
# 90 [ + + ]: 76551 : if (pos*2+1 < CalcTreeWidth(height-1))
# 91 : 76252 : TraverseAndBuild(height-1, pos*2+1, vTxid, vMatch);
# 92 : 76551 : }
# 93 : 153186 : }
# 94 : :
# 95 : 764842 : uint256 CPartialMerkleTree::TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
# 96 [ - + ]: 764842 : if (nBitsUsed >= vBits.size()) {
# 97 : : // overflowed the bits array - failure
# 98 : 0 : fBad = true;
# 99 : 0 : return uint256();
# 100 : 0 : }
# 101 : 764842 : bool fParentOfMatch = vBits[nBitsUsed++];
# 102 [ + + ][ + + ]: 764842 : if (height==0 || !fParentOfMatch) {
# 103 : : // if at height 0, or nothing interesting below, use stored hash and do not descend
# 104 [ - + ]: 382599 : if (nHashUsed >= vHash.size()) {
# 105 : : // overflowed the hash array - failure
# 106 : 0 : fBad = true;
# 107 : 0 : return uint256();
# 108 : 0 : }
# 109 : 382599 : const uint256 &hash = vHash[nHashUsed++];
# 110 [ + + ][ + + ]: 382599 : if (height==0 && fParentOfMatch) { // in case of height 0, we have a matched txid
# 111 : 191882 : vMatch.push_back(hash);
# 112 : 191882 : vnIndex.push_back(pos);
# 113 : 191882 : }
# 114 : 382599 : return hash;
# 115 : 382599 : } else {
# 116 : : // otherwise, descend into the subtrees to extract matched txids and hashes
# 117 : 382243 : uint256 left = TraverseAndExtract(height-1, pos*2, nBitsUsed, nHashUsed, vMatch, vnIndex), right;
# 118 [ + + ]: 382243 : if (pos*2+1 < CalcTreeWidth(height-1)) {
# 119 : 380870 : right = TraverseAndExtract(height-1, pos*2+1, nBitsUsed, nHashUsed, vMatch, vnIndex);
# 120 [ + + ]: 380870 : if (right == left) {
# 121 : : // The left and right branches should never be identical, as the transaction
# 122 : : // hashes covered by them must each be unique.
# 123 : 2 : fBad = true;
# 124 : 2 : }
# 125 : 380870 : } else {
# 126 : 1373 : right = left;
# 127 : 1373 : }
# 128 : : // and combine them before returning
# 129 : 382243 : return Hash(left, right);
# 130 : 382243 : }
# 131 : 764842 : }
# 132 : :
# 133 : 383 : CPartialMerkleTree::CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch) : nTransactions(vTxid.size()), fBad(false) {
# 134 : : // reset state
# 135 : 383 : vBits.clear();
# 136 : 383 : vHash.clear();
# 137 : :
# 138 : : // calculate height of tree
# 139 : 383 : int nHeight = 0;
# 140 [ + + ]: 2699 : while (CalcTreeWidth(nHeight) > 1)
# 141 : 2316 : nHeight++;
# 142 : :
# 143 : : // traverse the partial tree
# 144 : 383 : TraverseAndBuild(nHeight, 0, vTxid, vMatch);
# 145 : 383 : }
# 146 : :
# 147 : 413 : CPartialMerkleTree::CPartialMerkleTree() : nTransactions(0), fBad(true) {}
# 148 : :
# 149 : 1729 : uint256 CPartialMerkleTree::ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
# 150 : 1729 : vMatch.clear();
# 151 : : // An empty set will not work
# 152 [ - + ]: 1729 : if (nTransactions == 0)
# 153 : 0 : return uint256();
# 154 : : // check for excessively high numbers of transactions
# 155 [ - + ]: 1729 : if (nTransactions > MAX_BLOCK_WEIGHT / MIN_TRANSACTION_WEIGHT)
# 156 : 0 : return uint256();
# 157 : : // there can never be more hashes provided than one for every txid
# 158 [ - + ]: 1729 : if (vHash.size() > nTransactions)
# 159 : 0 : return uint256();
# 160 : : // there must be at least one bit per node in the partial tree, and at least one node per hash
# 161 [ - + ]: 1729 : if (vBits.size() < vHash.size())
# 162 : 0 : return uint256();
# 163 : : // calculate height of tree
# 164 : 1729 : int nHeight = 0;
# 165 [ + + ]: 12891 : while (CalcTreeWidth(nHeight) > 1)
# 166 : 11162 : nHeight++;
# 167 : : // traverse the partial tree
# 168 : 1729 : unsigned int nBitsUsed = 0, nHashUsed = 0;
# 169 : 1729 : uint256 hashMerkleRoot = TraverseAndExtract(nHeight, 0, nBitsUsed, nHashUsed, vMatch, vnIndex);
# 170 : : // verify that no problems occurred during the tree traversal
# 171 [ + + ]: 1729 : if (fBad)
# 172 : 2 : return uint256();
# 173 : : // verify that all bits were consumed (except for the padding caused by serializing it as a byte sequence)
# 174 [ - + ]: 1727 : if ((nBitsUsed+7)/8 != (vBits.size()+7)/8)
# 175 : 0 : return uint256();
# 176 : : // verify that all hashes were consumed
# 177 [ - + ]: 1727 : if (nHashUsed != vHash.size())
# 178 : 0 : return uint256();
# 179 : 1727 : return hashMerkleRoot;
# 180 : 1727 : }
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