zecfoundation
/
zcashd
mirror of https://github.com/ZcashFoundation/zcashd.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Auto merge of #4628 - therealyingtong:block-903002-bug, r=str4d 

Pass HistoryNode through Rust FFI as a C array

`std::array<T>` is guaranteed to store `T` contiguously. However, there is
no guarantee that `sizeof(std::array<unsigned char, N>) == N`, which
prevents us from interpreting `std::array<std::array<unsigned char, N>, 32>`
as `&[[u8; N]]` on the Rust side of the FFI.

Instead, we define `HistoryNode` as a struct wrapping a C array, which
(as checked by `static_assert`) contains no padding.

This is equivalent to 82fe37d22b, which
fixed this issue when passing a slice of `HistoryEntry`s from C++ to Rust;
the bug fixed here is writing `HistoryNodes` from Rust into C++ memory.
This commit is contained in:
Homu 2020-07-23 22:40:42 +00:00
parent d058568e0a 04b4d42767
commit de52eed974
5 changed files with 54 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/coins.cpp
View File

@ -467,7 +467,7 @@ void CCoinsViewCache::PushHistoryNode(uint32_t epochId, const HistoryNode node)
// special case, it just goes into the cache right away
historyCache.Extend(node);
if (librustzcash_mmr_hash_node(epochId, node.data(), historyCache.root.begin()) != 0) {
if (librustzcash_mmr_hash_node(epochId, &node, historyCache.root.begin()) != 0) {
throw std::runtime_error("hashing node failed");
};
@ -480,7 +480,7 @@ void CCoinsViewCache::PushHistoryNode(uint32_t epochId, const HistoryNode node)
PreloadHistoryTree(epochId, false, entries, entry_indices);
uint256 newRoot;
std::array<HistoryNode, 32> appendBuf;
std::array<HistoryNode, 32> appendBuf = {};
uint32_t appends = librustzcash_mmr_append(
epochId,
@ -488,9 +488,9 @@ void CCoinsViewCache::PushHistoryNode(uint32_t epochId, const HistoryNode node)
entry_indices.data(),
entries.data(),
entry_indices.size(),
node.data(),
&node,
newRoot.begin(),
appendBuf.data()->data()
appendBuf.data()
);
for (size_t i = 0; i < appends; i++) {
@ -506,6 +506,7 @@ void CCoinsViewCache::PopHistoryNode(uint32_t epochId) {
switch (historyCache.length) {
case 0:
{
// Caller is generally not expected to pop from empty tree! Caller
// should switch to previous epoch and pop history from there.
@ -517,22 +518,29 @@ void CCoinsViewCache::PopHistoryNode(uint32_t epochId) {
// back.
// Sensible action is to truncate the history cache:
}
case 1:
{
// Just resetting tree to empty
historyCache.Truncate(0);
historyCache.root = uint256();
return;
}
case 2:
{
// - A tree with one leaf has length 1.
// - A tree with two leaves has length 3.
throw std::runtime_error("a history tree cannot have two nodes");
}
case 3:
{
const HistoryNode tmpHistoryRoot = GetHistoryAt(epochId, 0);
// After removing a leaf from a tree with two leaves, we are left
// with a single-node tree, whose root is just the hash of that
// node.
if (librustzcash_mmr_hash_node(
epochId,
GetHistoryAt(epochId, 0).data(),
&tmpHistoryRoot,
newRoot.begin()
) != 0) {
throw std::runtime_error("hashing node failed");
@ -540,7 +548,9 @@ void CCoinsViewCache::PopHistoryNode(uint32_t epochId) {
historyCache.Truncate(1);
historyCache.root = newRoot;
return;
}
default:
{
// This is a non-elementary pop, so use the full tree logic.
std::vector<HistoryEntry> entries;
std::vector<uint32_t> entry_indices;
@ -560,6 +570,7 @@ void CCoinsViewCache::PopHistoryNode(uint32_t epochId) {
historyCache.Truncate(historyCache.length - numberOfDeletes);
historyCache.root = newRoot;
return;
}
}
}

17
src/rust/include/librustzcash.h
View File

@ -8,7 +8,16 @@
#include <stdalign.h>
#endif
#define ENTRY_SERIALIZED_LENGTH 180
#define NODE_SERIALIZED_LENGTH 171
#define ENTRY_SERIALIZED_LENGTH (NODE_SERIALIZED_LENGTH + 9)
typedef struct HistoryNode {
unsigned char bytes[NODE_SERIALIZED_LENGTH];
} HistoryNode;
static_assert(
sizeof(HistoryNode) == NODE_SERIALIZED_LENGTH,
"HistoryNode struct is not the same size as the underlying byte array");
static_assert(alignof(HistoryNode) == 1, "HistoryNode struct alignment is not 1");
typedef struct HistoryEntry {
unsigned char bytes[ENTRY_SERIALIZED_LENGTH];
@ -331,9 +340,9 @@ extern "C" {
const uint32_t *ni_ptr,
const HistoryEntry *n_ptr,
size_t p_len,
const unsigned char *nn_ptr,
const HistoryNode *nn_ptr,
unsigned char *rt_ret,
unsigned char *buf_ret
HistoryNode *buf_ret
);
uint32_t librustzcash_mmr_delete(
@ -348,7 +357,7 @@ extern "C" {
uint32_t librustzcash_mmr_hash_node(
uint32_t cbranch,
const unsigned char *n_ptr,
const HistoryNode *n_ptr,
unsigned char *h_ret
);

14
src/txdb.cpp
View File

@ -139,16 +139,21 @@ HistoryIndex CCoinsViewDB::GetHistoryLength(uint32_t epochId) const {
}
HistoryNode CCoinsViewDB::GetHistoryAt(uint32_t epochId, HistoryIndex index) const {
HistoryNode mmrNode;
HistoryNode mmrNode = {};
if (index >= GetHistoryLength(epochId)) {
throw runtime_error("History data inconsistent - reindex?");
}
if (!db.Read(make_pair(DB_MMR_NODE, make_pair(epochId, index)), mmrNode)) {
// Read mmrNode into tmp std::array
std::array<unsigned char, NODE_SERIALIZED_LENGTH> tmpMmrNode;
if (!db.Read(make_pair(DB_MMR_NODE, make_pair(epochId, index)), tmpMmrNode)) {
throw runtime_error("History data inconsistent (expected node not found) - reindex?");
}
std::copy(std::begin(tmpMmrNode), std::end(tmpMmrNode), mmrNode.bytes);
return mmrNode;
}
@ -205,7 +210,10 @@ void BatchWriteHistory(CDBBatch& batch, CHistoryCacheMap& historyCacheMap) {
// replace/append new/updated entries
for (auto it = historyCache.appends.begin(); it != historyCache.appends.end(); it++) {
batch.Write(make_pair(DB_MMR_NODE, make_pair(epochId, it->first)), it->second);
// Write mmrNode into tmp std::array
std::array<unsigned char, NODE_SERIALIZED_LENGTH> tmpMmrNode;
std::copy((it->second).bytes, (it->second).bytes + NODE_SERIALIZED_LENGTH, std::begin(tmpMmrNode));
batch.Write(make_pair(DB_MMR_NODE, make_pair(epochId, it->first)), tmpMmrNode);
}
// write new length

19
src/zcash/History.cpp
View File

@ -54,7 +54,7 @@ HistoryNode NewNode(
)
{
CDataStream buf(SER_DISK, 0);
HistoryNode result;
HistoryNode result = {};
buf << subtreeCommitment;
buf << startTime;
@ -68,7 +68,8 @@ HistoryNode NewNode(
buf << COMPACTSIZE(endHeight);
buf << COMPACTSIZE(saplingTxCount);
std::copy(buf.begin(), buf.end(), result.begin());
assert(buf.size() <= NODE_SERIALIZED_LENGTH);
std::copy(std::begin(buf), std::end(buf), result.bytes);
return result;
}
@ -104,7 +105,11 @@ HistoryEntry NodeToEntry(const HistoryNode node, uint32_t left, uint32_t right)
buf << code;
buf << left;
buf << right;
buf << node;
std::array<unsigned char, NODE_SERIALIZED_LENGTH> tmpMmrNode;
std::copy(node.bytes, node.bytes + NODE_SERIALIZED_LENGTH, std::begin(tmpMmrNode));
buf << tmpMmrNode;
assert(buf.size() <= ENTRY_SERIALIZED_LENGTH);
std::copy(std::begin(buf), std::end(buf), result.bytes);
@ -118,7 +123,11 @@ HistoryEntry LeafToEntry(const HistoryNode node) {
uint8_t code = 1;
buf << code;
buf << node;
std::array<unsigned char, NODE_SERIALIZED_LENGTH> tmpMmrNode;
std::copy(node.bytes, node.bytes + NODE_SERIALIZED_LENGTH, std::begin(tmpMmrNode));
buf << tmpMmrNode;
assert(buf.size() <= ENTRY_SERIALIZED_LENGTH);
std::copy(std::begin(buf), std::end(buf), result.bytes);
@ -126,4 +135,4 @@ HistoryEntry LeafToEntry(const HistoryNode node) {
return result;
}
}
}

5
src/zcash/History.hpp
View File

@ -13,10 +13,6 @@
namespace libzcash {
const int NODE_SERIALIZED_LENGTH = 171;
typedef std::array<unsigned char, NODE_SERIALIZED_LENGTH> HistoryNode;
typedef uint64_t HistoryIndex;
class HistoryCache {
@ -66,6 +62,5 @@ HistoryEntry LeafToEntry(const HistoryNode node);
typedef libzcash::HistoryCache HistoryCache;
typedef libzcash::HistoryIndex HistoryIndex;
typedef libzcash::HistoryNode HistoryNode;
#endif /* ZC_HISTORY_H_ */