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[MOVEONLY] Move unused Merkle branch code to tests 

Zcash: Also includes some minor changes from scripted diffs that
occurred between backported PRs.

(cherry picked from commit bitcoin/bitcoin@4defdfab94)
This commit is contained in:
Pieter Wuille 2018-05-12 11:48:41 -07:00 committed by Jack Grigg
parent ae3dc3f134
commit 6fc711d0d5
3 changed files with 119 additions and 124 deletions
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114
src/consensus/merkle.cpp
View File

@ -38,93 +38,6 @@
root.
*/
/* This implements a constant-space merkle root/path calculator, limited to 2^32 leaves. */
static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot, bool* pmutated, uint32_t branchpos, std::vector<uint256>* pbranch) {
if (pbranch) pbranch->clear();
if (leaves.size() == 0) {
if (pmutated) *pmutated = false;
if (proot) *proot = uint256();
return;
}
bool mutated = false;
// count is the number of leaves processed so far.
uint32_t count = 0;
// inner is an array of eagerly computed subtree hashes, indexed by tree
// level (0 being the leaves).
// For example, when count is 25 (11001 in binary), inner[4] is the hash of
// the first 16 leaves, inner[3] of the next 8 leaves, and inner[0] equal to
// the last leaf. The other inner entries are undefined.
uint256 inner[32];
// Which position in inner is a hash that depends on the matching leaf.
int matchlevel = -1;
// First process all leaves into 'inner' values.
while (count < leaves.size()) {
uint256 h = leaves[count];
bool matchh = count == branchpos;
count++;
int level;
// For each of the lower bits in count that are 0, do 1 step. Each
// corresponds to an inner value that existed before processing the
// current leaf, and each needs a hash to combine it.
for (level = 0; !(count & (((uint32_t)1) << level)); level++) {
if (pbranch) {
if (matchh) {
pbranch->push_back(inner[level]);
} else if (matchlevel == level) {
pbranch->push_back(h);
matchh = true;
}
}
mutated |= (inner[level] == h);
CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
}
// Store the resulting hash at inner position level.
inner[level] = h;
if (matchh) {
matchlevel = level;
}
}
// Do a final 'sweep' over the rightmost branch of the tree to process
// odd levels, and reduce everything to a single top value.
// Level is the level (counted from the bottom) up to which we've sweeped.
int level = 0;
// As long as bit number level in count is zero, skip it. It means there
// is nothing left at this level.
while (!(count & (((uint32_t)1) << level))) {
level++;
}
uint256 h = inner[level];
bool matchh = matchlevel == level;
while (count != (((uint32_t)1) << level)) {
// If we reach this point, h is an inner value that is not the top.
// We combine it with itself (Bitcoin's special rule for odd levels in
// the tree) to produce a higher level one.
if (pbranch && matchh) {
pbranch->push_back(h);
}
CHash256().Write(h.begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
// Increment count to the value it would have if two entries at this
// level had existed.
count += (((uint32_t)1) << level);
level++;
// And propagate the result upwards accordingly.
while (!(count & (((uint32_t)1) << level))) {
if (pbranch) {
if (matchh) {
pbranch->push_back(inner[level]);
} else if (matchlevel == level) {
pbranch->push_back(h);
matchh = true;
}
}
CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
level++;
}
}
// Return result.
if (pmutated) *pmutated = mutated;
if (proot) *proot = h;
}
uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated) {
bool mutation = false;
@ -145,24 +58,6 @@ uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated) {
return hashes[0];
}
std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position) {
std::vector<uint256> ret;
MerkleComputation(leaves, NULL, NULL, position, &ret);
return ret;
}
uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& vMerkleBranch, uint32_t nIndex) {
uint256 hash = leaf;
for (std::vector<uint256>::const_iterator it = vMerkleBranch.begin(); it != vMerkleBranch.end(); ++it) {
if (nIndex & 1) {
hash = Hash(BEGIN(*it), END(*it), BEGIN(hash), END(hash));
} else {
hash = Hash(BEGIN(hash), END(hash), BEGIN(*it), END(*it));
}
nIndex >>= 1;
}
return hash;
}
uint256 BlockMerkleRoot(const CBlock& block, bool* mutated)
{
@ -174,12 +69,3 @@ uint256 BlockMerkleRoot(const CBlock& block, bool* mutated)
return ComputeMerkleRoot(std::move(leaves), mutated);
}
std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position)
{
std::vector<uint256> leaves;
leaves.resize(block.vtx.size());
for (size_t s = 0; s < block.vtx.size(); s++) {
leaves[s] = block.vtx[s].GetHash();
}
return ComputeMerkleBranch(leaves, position);
}

11
src/consensus/merkle.h
View File

@ -12,9 +12,7 @@
#include "primitives/block.h"
#include "uint256.h"
uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated);
std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position);
uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& branch, uint32_t position);
uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated = nullptr);
/*
* Compute the Merkle root of the transactions in a block.
@ -22,11 +20,4 @@ uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint2
*/
uint256 BlockMerkleRoot(const CBlock& block, bool* mutated = NULL);
/*
* Compute the Merkle branch for the tree of transactions in a block, for a
* given position.
* This can be verified using ComputeMerkleRootFromBranch.
*/
std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position);
#endif // BITCOIN_CONSENSUS_MERKLE_H

118
src/test/merkle_tests.cpp
View File

@ -4,11 +4,129 @@
#include "consensus/merkle.h"
#include "test/test_bitcoin.h"
#include "util/strencodings.h"
#include <boost/test/unit_test.hpp>
BOOST_FIXTURE_TEST_SUITE(merkle_tests, TestingSetup)
static uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& vMerkleBranch, uint32_t nIndex) {
uint256 hash = leaf;
for (std::vector<uint256>::const_iterator it = vMerkleBranch.begin(); it != vMerkleBranch.end(); ++it) {
if (nIndex & 1) {
hash = Hash(BEGIN(*it), END(*it), BEGIN(hash), END(hash));
} else {
hash = Hash(BEGIN(hash), END(hash), BEGIN(*it), END(*it));
}
nIndex >>= 1;
}
return hash;
}
/* This implements a constant-space merkle root/path calculator, limited to 2^32 leaves. */
static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot, bool* pmutated, uint32_t branchpos, std::vector<uint256>* pbranch) {
if (pbranch) pbranch->clear();
if (leaves.size() == 0) {
if (pmutated) *pmutated = false;
if (proot) *proot = uint256();
return;
}
bool mutated = false;
// count is the number of leaves processed so far.
uint32_t count = 0;
// inner is an array of eagerly computed subtree hashes, indexed by tree
// level (0 being the leaves).
// For example, when count is 25 (11001 in binary), inner[4] is the hash of
// the first 16 leaves, inner[3] of the next 8 leaves, and inner[0] equal to
// the last leaf. The other inner entries are undefined.
uint256 inner[32];
// Which position in inner is a hash that depends on the matching leaf.
int matchlevel = -1;
// First process all leaves into 'inner' values.
while (count < leaves.size()) {
uint256 h = leaves[count];
bool matchh = count == branchpos;
count++;
int level;
// For each of the lower bits in count that are 0, do 1 step. Each
// corresponds to an inner value that existed before processing the
// current leaf, and each needs a hash to combine it.
for (level = 0; !(count & (((uint32_t)1) << level)); level++) {
if (pbranch) {
if (matchh) {
pbranch->push_back(inner[level]);
} else if (matchlevel == level) {
pbranch->push_back(h);
matchh = true;
}
}
mutated |= (inner[level] == h);
CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
}
// Store the resulting hash at inner position level.
inner[level] = h;
if (matchh) {
matchlevel = level;
}
}
// Do a final 'sweep' over the rightmost branch of the tree to process
// odd levels, and reduce everything to a single top value.
// Level is the level (counted from the bottom) up to which we've sweeped.
int level = 0;
// As long as bit number level in count is zero, skip it. It means there
// is nothing left at this level.
while (!(count & (((uint32_t)1) << level))) {
level++;
}
uint256 h = inner[level];
bool matchh = matchlevel == level;
while (count != (((uint32_t)1) << level)) {
// If we reach this point, h is an inner value that is not the top.
// We combine it with itself (Bitcoin's special rule for odd levels in
// the tree) to produce a higher level one.
if (pbranch && matchh) {
pbranch->push_back(h);
}
CHash256().Write(h.begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
// Increment count to the value it would have if two entries at this
// level had existed.
count += (((uint32_t)1) << level);
level++;
// And propagate the result upwards accordingly.
while (!(count & (((uint32_t)1) << level))) {
if (pbranch) {
if (matchh) {
pbranch->push_back(inner[level]);
} else if (matchlevel == level) {
pbranch->push_back(h);
matchh = true;
}
}
CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
level++;
}
}
// Return result.
if (pmutated) *pmutated = mutated;
if (proot) *proot = h;
}
static std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position) {
std::vector<uint256> ret;
MerkleComputation(leaves, nullptr, nullptr, position, &ret);
return ret;
}
static std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position)
{
std::vector<uint256> leaves;
leaves.resize(block.vtx.size());
for (size_t s = 0; s < block.vtx.size(); s++) {
leaves[s] = block.vtx[s].GetHash();
}
return ComputeMerkleBranch(leaves, position);
}
// Older version of the merkle root computation code, for comparison.
static uint256 BlockBuildMerkleTree(const CBlock& block, bool* fMutated, std::vector<uint256>& vMerkleTree)
{