Branch data Line data Source code
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 : 0 : std::vector<unsigned char> BitsToBytes(const std::vector<bool>& bits)
13 : : {
14 [ # # ]: 0 : std::vector<unsigned char> ret((bits.size() + 7) / 8);
15 [ # # ]: 0 : for (unsigned int p = 0; p < bits.size(); p++) {
16 [ # # ]: 0 : ret[p / 8] |= bits[p] << (p % 8);
17 : 0 : }
18 : 0 : return ret;
19 [ # # ]: 0 : }
20 : :
21 : 0 : std::vector<bool> BytesToBits(const std::vector<unsigned char>& bytes)
22 : : {
23 [ # # ]: 0 : std::vector<bool> ret(bytes.size() * 8);
24 [ # # ]: 0 : for (unsigned int p = 0; p < ret.size(); p++) {
25 [ # # ]: 0 : ret[p] = (bytes[p / 8] & (1 << (p % 8))) != 0;
26 : 0 : }
27 : 0 : return ret;
28 [ # # ]: 0 : }
29 : :
30 : 0 : CMerkleBlock::CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids)
31 : : {
32 [ # # ]: 0 : header = block.GetBlockHeader();
33 : :
34 : 0 : std::vector<bool> vMatch;
35 : 0 : std::vector<uint256> vHashes;
36 : :
37 [ # # ]: 0 : vMatch.reserve(block.vtx.size());
38 [ # # ]: 0 : vHashes.reserve(block.vtx.size());
39 : :
40 [ # # ]: 0 : for (unsigned int i = 0; i < block.vtx.size(); i++)
41 : : {
42 [ # # ]: 0 : const uint256& hash = block.vtx[i]->GetHash();
43 [ # # # # : 0 : if (txids && txids->count(hash)) {
# # ]
44 [ # # ]: 0 : vMatch.push_back(true);
45 [ # # # # : 0 : } else if (filter && filter->IsRelevantAndUpdate(*block.vtx[i])) {
# # ]
46 [ # # ]: 0 : vMatch.push_back(true);
47 [ # # ]: 0 : vMatchedTxn.emplace_back(i, hash);
48 : 0 : } else {
49 [ # # ]: 0 : vMatch.push_back(false);
50 : : }
51 [ # # ]: 0 : vHashes.push_back(hash);
52 : 0 : }
53 : :
54 [ # # ]: 0 : txn = CPartialMerkleTree(vHashes, vMatch);
55 : 0 : }
56 : :
57 : 0 : 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 [ # # ]: 0 : assert(vTxid.size() != 0);
61 [ # # ]: 0 : if (height == 0) {
62 : : // hash at height 0 is the txids themselves
63 : 0 : return vTxid[pos];
64 : : } else {
65 : : // calculate left hash
66 : 0 : 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 [ # # ]: 0 : if (pos*2+1 < CalcTreeWidth(height-1))
69 : 0 : right = CalcHash(height-1, pos*2+1, vTxid);
70 : : else
71 : 0 : right = left;
72 : : // combine subhashes
73 : 0 : return Hash(left, right);
74 : : }
75 : 0 : }
76 : :
77 : 0 : 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 : 0 : bool fParentOfMatch = false;
80 [ # # # # ]: 0 : for (unsigned int p = pos << height; p < (pos+1) << height && p < nTransactions; p++)
81 : 0 : fParentOfMatch |= vMatch[p];
82 : : // store as flag bit
83 : 0 : vBits.push_back(fParentOfMatch);
84 [ # # # # ]: 0 : if (height==0 || !fParentOfMatch) {
85 : : // if at height 0, or nothing interesting below, store hash and stop
86 : 0 : vHash.push_back(CalcHash(height, pos, vTxid));
87 : 0 : } else {
88 : : // otherwise, don't store any hash, but descend into the subtrees
89 : 0 : TraverseAndBuild(height-1, pos*2, vTxid, vMatch);
90 [ # # ]: 0 : if (pos*2+1 < CalcTreeWidth(height-1))
91 : 0 : TraverseAndBuild(height-1, pos*2+1, vTxid, vMatch);
92 : : }
93 : 0 : }
94 : :
95 : 0 : uint256 CPartialMerkleTree::TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
96 [ # # ]: 0 : if (nBitsUsed >= vBits.size()) {
97 : : // overflowed the bits array - failure
98 : 0 : fBad = true;
99 : 0 : return uint256();
100 : : }
101 : 0 : bool fParentOfMatch = vBits[nBitsUsed++];
102 [ # # # # ]: 0 : if (height==0 || !fParentOfMatch) {
103 : : // if at height 0, or nothing interesting below, use stored hash and do not descend
104 [ # # ]: 0 : if (nHashUsed >= vHash.size()) {
105 : : // overflowed the hash array - failure
106 : 0 : fBad = true;
107 : 0 : return uint256();
108 : : }
109 : 0 : const uint256 &hash = vHash[nHashUsed++];
110 [ # # # # ]: 0 : if (height==0 && fParentOfMatch) { // in case of height 0, we have a matched txid
111 : 0 : vMatch.push_back(hash);
112 : 0 : vnIndex.push_back(pos);
113 : 0 : }
114 : 0 : return hash;
115 : : } else {
116 : : // otherwise, descend into the subtrees to extract matched txids and hashes
117 : 0 : uint256 left = TraverseAndExtract(height-1, pos*2, nBitsUsed, nHashUsed, vMatch, vnIndex), right;
118 [ # # ]: 0 : if (pos*2+1 < CalcTreeWidth(height-1)) {
119 : 0 : right = TraverseAndExtract(height-1, pos*2+1, nBitsUsed, nHashUsed, vMatch, vnIndex);
120 [ # # ]: 0 : 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 : 0 : fBad = true;
124 : 0 : }
125 : 0 : } else {
126 : 0 : right = left;
127 : : }
128 : : // and combine them before returning
129 : 0 : return Hash(left, right);
130 : : }
131 : 0 : }
132 : :
133 : 0 : CPartialMerkleTree::CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch) : nTransactions(vTxid.size()), fBad(false) {
134 : : // reset state
135 : 0 : vBits.clear();
136 : 0 : vHash.clear();
137 : :
138 : : // calculate height of tree
139 : 0 : int nHeight = 0;
140 [ # # # # ]: 0 : while (CalcTreeWidth(nHeight) > 1)
141 : 0 : nHeight++;
142 : :
143 : : // traverse the partial tree
144 [ # # ]: 0 : TraverseAndBuild(nHeight, 0, vTxid, vMatch);
145 : 0 : }
146 : :
147 : 0 : CPartialMerkleTree::CPartialMerkleTree() : nTransactions(0), fBad(true) {}
148 : :
149 : 0 : uint256 CPartialMerkleTree::ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
150 : 0 : vMatch.clear();
151 : : // An empty set will not work
152 [ # # ]: 0 : if (nTransactions == 0)
153 : 0 : return uint256();
154 : : // check for excessively high numbers of transactions
155 [ # # ]: 0 : 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 [ # # ]: 0 : 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 [ # # ]: 0 : if (vBits.size() < vHash.size())
162 : 0 : return uint256();
163 : : // calculate height of tree
164 : 0 : int nHeight = 0;
165 [ # # ]: 0 : while (CalcTreeWidth(nHeight) > 1)
166 : 0 : nHeight++;
167 : : // traverse the partial tree
168 : 0 : unsigned int nBitsUsed = 0, nHashUsed = 0;
169 : 0 : uint256 hashMerkleRoot = TraverseAndExtract(nHeight, 0, nBitsUsed, nHashUsed, vMatch, vnIndex);
170 : : // verify that no problems occurred during the tree traversal
171 [ # # ]: 0 : if (fBad)
172 : 0 : return uint256();
173 : : // verify that all bits were consumed (except for the padding caused by serializing it as a byte sequence)
174 [ # # ]: 0 : if ((nBitsUsed+7)/8 != (vBits.size()+7)/8)
175 : 0 : return uint256();
176 : : // verify that all hashes were consumed
177 [ # # ]: 0 : if (nHashUsed != vHash.size())
178 : 0 : return uint256();
179 : 0 : return hashMerkleRoot;
180 : 0 : }
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