Initial Vexta Core v0.1.0 release

src/merkleblock.cpp

@@ -0,0 +1,181 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The Bitcoin Core developers
+// Copyright (c) 2014-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <merkleblock.h>
+
+#include <hash.h>
+#include <consensus/consensus.h>
+
+
+std::vector<unsigned char> BitsToBytes(const std::vector<bool>& bits)
+{
+    std::vector<unsigned char> ret((bits.size() + 7) / 8);
+    for (unsigned int p = 0; p < bits.size(); p++) {
+        ret[p / 8] |= bits[p] << (p % 8);
+    }
+    return ret;
+}
+
+std::vector<bool> BytesToBits(const std::vector<unsigned char>& bytes)
+{
+    std::vector<bool> ret(bytes.size() * 8);
+    for (unsigned int p = 0; p < ret.size(); p++) {
+        ret[p] = (bytes[p / 8] & (1 << (p % 8))) != 0;
+    }
+    return ret;
+}
+
+CMerkleBlock::CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids)
+{
+    header = block.GetBlockHeader();
+
+    std::vector<bool> vMatch;
+    std::vector<uint256> vHashes;
+
+    vMatch.reserve(block.vtx.size());
+    vHashes.reserve(block.vtx.size());
+
+    for (unsigned int i = 0; i < block.vtx.size(); i++)
+    {
+        const uint256& hash = block.vtx[i]->GetHash();
+        if (txids && txids->count(hash)) {
+            vMatch.push_back(true);
+        } else if (filter && filter->IsRelevantAndUpdate(*block.vtx[i])) {
+            vMatch.push_back(true);
+            vMatchedTxn.emplace_back(i, hash);
+        } else {
+            vMatch.push_back(false);
+        }
+        vHashes.push_back(hash);
+    }
+
+    txn = CPartialMerkleTree(vHashes, vMatch);
+}
+
+uint256 CPartialMerkleTree::CalcHash(int height, unsigned int pos, const std::vector<uint256> &vTxid) {
+    //we can never have zero txs in a merkle block, we always need the coinbase tx
+    //if we do not have this assert, we can hit a memory access violation when indexing into vTxid
+    assert(vTxid.size() != 0);
+    if (height == 0) {
+        // hash at height 0 is the txids themselves
+        return vTxid[pos];
+    } else {
+        // calculate left hash
+        uint256 left = CalcHash(height-1, pos*2, vTxid), right;
+        // calculate right hash if not beyond the end of the array - copy left hash otherwise
+        if (pos*2+1 < CalcTreeWidth(height-1))
+            right = CalcHash(height-1, pos*2+1, vTxid);
+        else
+            right = left;
+        // combine subhashes
+        return Hash(left, right);
+    }
+}
+
+void CPartialMerkleTree::TraverseAndBuild(int height, unsigned int pos, const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch) {
+    // determine whether this node is the parent of at least one matched txid
+    bool fParentOfMatch = false;
+    for (unsigned int p = pos << height; p < (pos+1) << height && p < nTransactions; p++)
+        fParentOfMatch |= vMatch[p];
+    // store as flag bit
+    vBits.push_back(fParentOfMatch);
+    if (height==0 || !fParentOfMatch) {
+        // if at height 0, or nothing interesting below, store hash and stop
+        vHash.push_back(CalcHash(height, pos, vTxid));
+    } else {
+        // otherwise, don't store any hash, but descend into the subtrees
+        TraverseAndBuild(height-1, pos*2, vTxid, vMatch);
+        if (pos*2+1 < CalcTreeWidth(height-1))
+            TraverseAndBuild(height-1, pos*2+1, vTxid, vMatch);
+    }
+}
+
+uint256 CPartialMerkleTree::TraverseAndExtract(int height, unsigned int pos, unsigned int &nBitsUsed, unsigned int &nHashUsed, std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
+    if (nBitsUsed >= vBits.size()) {
+        // overflowed the bits array - failure
+        fBad = true;
+        return uint256();
+    }
+    bool fParentOfMatch = vBits[nBitsUsed++];
+    if (height==0 || !fParentOfMatch) {
+        // if at height 0, or nothing interesting below, use stored hash and do not descend
+        if (nHashUsed >= vHash.size()) {
+            // overflowed the hash array - failure
+            fBad = true;
+            return uint256();
+        }
+        const uint256 &hash = vHash[nHashUsed++];
+        if (height==0 && fParentOfMatch) { // in case of height 0, we have a matched txid
+            vMatch.push_back(hash);
+            vnIndex.push_back(pos);
+        }
+        return hash;
+    } else {
+        // otherwise, descend into the subtrees to extract matched txids and hashes
+        uint256 left = TraverseAndExtract(height-1, pos*2, nBitsUsed, nHashUsed, vMatch, vnIndex), right;
+        if (pos*2+1 < CalcTreeWidth(height-1)) {
+            right = TraverseAndExtract(height-1, pos*2+1, nBitsUsed, nHashUsed, vMatch, vnIndex);
+            if (right == left) {
+                // The left and right branches should never be identical, as the transaction
+                // hashes covered by them must each be unique.
+                fBad = true;
+            }
+        } else {
+            right = left;
+        }
+        // and combine them before returning
+        return Hash(left, right);
+    }
+}
+
+CPartialMerkleTree::CPartialMerkleTree(const std::vector<uint256> &vTxid, const std::vector<bool> &vMatch) : nTransactions(vTxid.size()), fBad(false) {
+    // reset state
+    vBits.clear();
+    vHash.clear();
+
+    // calculate height of tree
+    int nHeight = 0;
+    while (CalcTreeWidth(nHeight) > 1)
+        nHeight++;
+
+    // traverse the partial tree
+    TraverseAndBuild(nHeight, 0, vTxid, vMatch);
+}
+
+CPartialMerkleTree::CPartialMerkleTree() : nTransactions(0), fBad(true) {}
+
+uint256 CPartialMerkleTree::ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex) {
+    vMatch.clear();
+    // An empty set will not work
+    if (nTransactions == 0)
+        return uint256();
+    // check for excessively high numbers of transactions
+    if (nTransactions > MAX_BLOCK_WEIGHT / MIN_TRANSACTION_WEIGHT)
+        return uint256();
+    // there can never be more hashes provided than one for every txid
+    if (vHash.size() > nTransactions)
+        return uint256();
+    // there must be at least one bit per node in the partial tree, and at least one node per hash
+    if (vBits.size() < vHash.size())
+        return uint256();
+    // calculate height of tree
+    int nHeight = 0;
+    while (CalcTreeWidth(nHeight) > 1)
+        nHeight++;
+    // traverse the partial tree
+    unsigned int nBitsUsed = 0, nHashUsed = 0;
+    uint256 hashMerkleRoot = TraverseAndExtract(nHeight, 0, nBitsUsed, nHashUsed, vMatch, vnIndex);
+    // verify that no problems occurred during the tree traversal
+    if (fBad)
+        return uint256();
+    // verify that all bits were consumed (except for the padding caused by serializing it as a byte sequence)
+    if ((nBitsUsed+7)/8 != (vBits.size()+7)/8)
+        return uint256();
+    // verify that all hashes were consumed
+    if (nHashUsed != vHash.size())
+        return uint256();
+    return hashMerkleRoot;
+}