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-rw-r--r--src/test/merkle_tests.cpp136
1 files changed, 136 insertions, 0 deletions
diff --git a/src/test/merkle_tests.cpp b/src/test/merkle_tests.cpp
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+// Copyright (c) 2015 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "consensus/merkle.h"
+#include "test/test_bitcoin.h"
+#include "random.h"
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(merkle_tests, TestingSetup)
+
+// Older version of the merkle root computation code, for comparison.
+static uint256 BlockBuildMerkleTree(const CBlock& block, bool* fMutated, std::vector<uint256>& vMerkleTree)
+{
+ vMerkleTree.clear();
+ vMerkleTree.reserve(block.vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes.
+ for (std::vector<CTransaction>::const_iterator it(block.vtx.begin()); it != block.vtx.end(); ++it)
+ vMerkleTree.push_back(it->GetHash());
+ int j = 0;
+ bool mutated = false;
+ for (int nSize = block.vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+ {
+ for (int i = 0; i < nSize; i += 2)
+ {
+ int i2 = std::min(i+1, nSize-1);
+ if (i2 == i + 1 && i2 + 1 == nSize && vMerkleTree[j+i] == vMerkleTree[j+i2]) {
+ // Two identical hashes at the end of the list at a particular level.
+ mutated = true;
+ }
+ vMerkleTree.push_back(Hash(vMerkleTree[j+i].begin(), vMerkleTree[j+i].end(),
+ vMerkleTree[j+i2].begin(), vMerkleTree[j+i2].end()));
+ }
+ j += nSize;
+ }
+ if (fMutated) {
+ *fMutated = mutated;
+ }
+ return (vMerkleTree.empty() ? uint256() : vMerkleTree.back());
+}
+
+// Older version of the merkle branch computation code, for comparison.
+static std::vector<uint256> BlockGetMerkleBranch(const CBlock& block, const std::vector<uint256>& vMerkleTree, int nIndex)
+{
+ std::vector<uint256> vMerkleBranch;
+ int j = 0;
+ for (int nSize = block.vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+ {
+ int i = std::min(nIndex^1, nSize-1);
+ vMerkleBranch.push_back(vMerkleTree[j+i]);
+ nIndex >>= 1;
+ j += nSize;
+ }
+ return vMerkleBranch;
+}
+
+static inline int ctz(uint32_t i) {
+ if (i == 0) return 0;
+ int j = 0;
+ while (!(i & 1)) {
+ j++;
+ i >>= 1;
+ }
+ return j;
+}
+
+BOOST_AUTO_TEST_CASE(merkle_test)
+{
+ for (int i = 0; i < 32; i++) {
+ // Try 32 block sizes: all sizes from 0 to 16 inclusive, and then 15 random sizes.
+ int ntx = (i <= 16) ? i : 17 + (insecure_rand() % 4000);
+ // Try up to 3 mutations.
+ for (int mutate = 0; mutate <= 3; mutate++) {
+ int duplicate1 = mutate >= 1 ? 1 << ctz(ntx) : 0; // The last how many transactions to duplicate first.
+ if (duplicate1 >= ntx) break; // Duplication of the entire tree results in a different root (it adds a level).
+ int ntx1 = ntx + duplicate1; // The resulting number of transactions after the first duplication.
+ int duplicate2 = mutate >= 2 ? 1 << ctz(ntx1) : 0; // Likewise for the second mutation.
+ if (duplicate2 >= ntx1) break;
+ int ntx2 = ntx1 + duplicate2;
+ int duplicate3 = mutate >= 3 ? 1 << ctz(ntx2) : 0; // And for the third mutation.
+ if (duplicate3 >= ntx2) break;
+ int ntx3 = ntx2 + duplicate3;
+ // Build a block with ntx different transactions.
+ CBlock block;
+ block.vtx.resize(ntx);
+ for (int j = 0; j < ntx; j++) {
+ CMutableTransaction mtx;
+ mtx.nLockTime = j;
+ block.vtx[j] = mtx;
+ }
+ // Compute the root of the block before mutating it.
+ bool unmutatedMutated = false;
+ uint256 unmutatedRoot = BlockMerkleRoot(block, &unmutatedMutated);
+ BOOST_CHECK(unmutatedMutated == false);
+ // Optionally mutate by duplicating the last transactions, resulting in the same merkle root.
+ block.vtx.resize(ntx3);
+ for (int j = 0; j < duplicate1; j++) {
+ block.vtx[ntx + j] = block.vtx[ntx + j - duplicate1];
+ }
+ for (int j = 0; j < duplicate2; j++) {
+ block.vtx[ntx1 + j] = block.vtx[ntx1 + j - duplicate2];
+ }
+ for (int j = 0; j < duplicate3; j++) {
+ block.vtx[ntx2 + j] = block.vtx[ntx2 + j - duplicate3];
+ }
+ // Compute the merkle root and merkle tree using the old mechanism.
+ bool oldMutated = false;
+ std::vector<uint256> merkleTree;
+ uint256 oldRoot = BlockBuildMerkleTree(block, &oldMutated, merkleTree);
+ // Compute the merkle root using the new mechanism.
+ bool newMutated = false;
+ uint256 newRoot = BlockMerkleRoot(block, &newMutated);
+ BOOST_CHECK(oldRoot == newRoot);
+ BOOST_CHECK(newRoot == unmutatedRoot);
+ BOOST_CHECK((newRoot == uint256()) == (ntx == 0));
+ BOOST_CHECK(oldMutated == newMutated);
+ BOOST_CHECK(newMutated == !!mutate);
+ // If no mutation was done (once for every ntx value), try up to 16 branches.
+ if (mutate == 0) {
+ for (int loop = 0; loop < std::min(ntx, 16); loop++) {
+ // If ntx <= 16, try all branches. Otherise, try 16 random ones.
+ int mtx = loop;
+ if (ntx > 16) {
+ mtx = insecure_rand() % ntx;
+ }
+ std::vector<uint256> newBranch = BlockMerkleBranch(block, mtx);
+ std::vector<uint256> oldBranch = BlockGetMerkleBranch(block, merkleTree, mtx);
+ BOOST_CHECK(oldBranch == newBranch);
+ BOOST_CHECK(ComputeMerkleRootFromBranch(block.vtx[mtx].GetHash(), newBranch, mtx) == oldRoot);
+ }
+ }
+ }
+ }
+}
+
+BOOST_AUTO_TEST_SUITE_END()