Merge #9107: Safer modify new coins
b50cd7a Fix dangerous condition in ModifyNewCoins. (Alex Morcos)This commit is contained in:
Pieter Wuille
commit
7dac1e5e9e
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@ -117,17 +117,37 @@ CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
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return CCoinsModifier(*this, ret.first, cachedCoinUsage);
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}
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// ModifyNewCoins has to know whether the new outputs its creating are for a
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// coinbase or not. If they are for a coinbase, it can not mark them as fresh.
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// This is to ensure that the historical duplicate coinbases before BIP30 was
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// in effect will still be properly overwritten when spent.
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/* ModifyNewCoins allows for faster coin modification when creating the new
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* outputs from a transaction. It assumes that BIP 30 (no duplicate txids)
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* applies and has already been tested for (or the test is not required due to
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* BIP 34, height in coinbase). If we can assume BIP 30 then we know that any
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* non-coinbase transaction we are adding to the UTXO must not already exist in
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* the utxo unless it is fully spent. Thus we can check only if it exists DIRTY
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* at the current level of the cache, in which case it is not safe to mark it
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* FRESH (b/c then its spentness still needs to flushed). If it's not dirty and
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* doesn't exist or is pruned in the current cache, we know it either doesn't
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* exist or is pruned in parent caches, which is the definition of FRESH. The
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* exception to this is the two historical violations of BIP 30 in the chain,
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* both of which were coinbases. We do not mark these fresh so we we can ensure
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* that they will still be properly overwritten when spent.
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*/
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CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid, bool coinbase) {
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assert(!hasModifier);
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std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
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ret.first->second.coins.Clear();
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if (!coinbase) {
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ret.first->second.flags = CCoinsCacheEntry::FRESH;
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// New coins must not already exist.
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if (!ret.first->second.coins.IsPruned())
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throw std::logic_error("ModifyNewCoins should not find pre-existing coins on a non-coinbase unless they are pruned!");
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if (!(ret.first->second.flags & CCoinsCacheEntry::DIRTY)) {
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// If the coin is known to be pruned (have no unspent outputs) in
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// the current view and the cache entry is not dirty, we know the
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// coin also must be pruned in the parent view as well, so it is safe
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// to mark this fresh.
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ret.first->second.flags |= CCoinsCacheEntry::FRESH;
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}
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}
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ret.first->second.coins.Clear();
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ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
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return CCoinsModifier(*this, ret.first, 0);
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}
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@ -200,6 +220,11 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
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itUs->second.coins.swap(it->second.coins);
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cachedCoinsUsage += itUs->second.coins.DynamicMemoryUsage();
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itUs->second.flags |= CCoinsCacheEntry::DIRTY;
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// NOTE: It is possible the child has a FRESH flag here in
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// the event the entry we found in the parent is pruned. But
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// we must not copy that FRESH flag to the parent as that
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// pruned state likely still needs to be communicated to the
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// grandparent.
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}
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}
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}
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@ -269,6 +269,11 @@ struct CCoinsCacheEntry
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enum Flags {
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DIRTY = (1 << 0), // This cache entry is potentially different from the version in the parent view.
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FRESH = (1 << 1), // The parent view does not have this entry (or it is pruned).
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/* Note that FRESH is a performance optimization with which we can
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* erase coins that are fully spent if we know we do not need to
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* flush the changes to the parent cache. It is always safe to
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* not mark FRESH if that condition is not guaranteed.
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*/
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};
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CCoinsCacheEntry() : coins(), flags(0) {}
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@ -5,6 +5,7 @@
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#include "coins.h"
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#include "script/standard.h"
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#include "uint256.h"
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#include "undo.h"
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#include "utilstrencodings.h"
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#include "test/test_bitcoin.h"
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#include "test/test_random.h"
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@ -16,6 +17,9 @@
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#include <boost/test/unit_test.hpp>
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bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const COutPoint& out);
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void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, CTxUndo &txundo, int nHeight);
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namespace
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{
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class CCoinsViewTest : public CCoinsView
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@ -213,6 +217,22 @@ BOOST_AUTO_TEST_CASE(coins_cache_simulation_test)
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BOOST_CHECK(missed_an_entry);
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}
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typedef std::tuple<CTransaction,CTxUndo,CCoins> TxData;
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// Store of all necessary tx and undo data for next test
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std::map<uint256, TxData> alltxs;
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TxData &FindRandomFrom(const std::set<uint256> &txidset) {
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assert(txidset.size());
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std::set<uint256>::iterator txIt = txidset.lower_bound(GetRandHash());
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if (txIt == txidset.end()) {
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txIt = txidset.begin();
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}
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std::map<uint256, TxData>::iterator txdit = alltxs.find(*txIt);
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assert(txdit != alltxs.end());
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return txdit->second;
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}
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// This test is similar to the previous test
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// except the emphasis is on testing the functionality of UpdateCoins
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// random txs are created and UpdateCoins is used to update the cache stack
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@ -229,77 +249,139 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
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std::vector<CCoinsViewCacheTest*> stack; // A stack of CCoinsViewCaches on top.
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stack.push_back(new CCoinsViewCacheTest(&base)); // Start with one cache.
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// Track the txids we've used and whether they have been spent or not
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std::map<uint256, CAmount> coinbaseids;
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std::set<uint256> alltxids;
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// Track the txids we've used in various sets
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std::set<uint256> coinbaseids;
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std::set<uint256> disconnectedids;
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std::set<uint256> duplicateids;
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std::set<uint256> utxoset;
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for (unsigned int i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
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{
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uint32_t randiter = insecure_rand();
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// 19/20 txs add a new transaction
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if (randiter % 20 < 19) {
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CMutableTransaction tx;
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tx.vin.resize(1);
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tx.vout.resize(1);
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tx.vout[0].nValue = i; //Keep txs unique unless intended to duplicate
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unsigned int height = insecure_rand();
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CCoins oldcoins;
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// 1/10 times create a coinbase
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if (insecure_rand() % 10 == 0 || coinbaseids.size() < 10) {
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// 1/100 times create a duplicate coinbase
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// 2/20 times create a new coinbase
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if (randiter % 20 < 2 || coinbaseids.size() < 10) {
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// 1/10 of those times create a duplicate coinbase
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if (insecure_rand() % 10 == 0 && coinbaseids.size()) {
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std::map<uint256, CAmount>::iterator coinbaseIt = coinbaseids.lower_bound(GetRandHash());
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if (coinbaseIt == coinbaseids.end()) {
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coinbaseIt = coinbaseids.begin();
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}
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//Use same random value to have same hash and be a true duplicate
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tx.vout[0].nValue = coinbaseIt->second;
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assert(tx.GetHash() == coinbaseIt->first);
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duplicateids.insert(coinbaseIt->first);
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TxData &txd = FindRandomFrom(coinbaseids);
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// Reuse the exact same coinbase
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tx = std::get<0>(txd);
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// shouldn't be available for reconnection if its been duplicated
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disconnectedids.erase(tx.GetHash());
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duplicateids.insert(tx.GetHash());
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}
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else {
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coinbaseids[tx.GetHash()] = tx.vout[0].nValue;
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coinbaseids.insert(tx.GetHash());
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}
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assert(CTransaction(tx).IsCoinBase());
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}
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// 9/10 times create a regular tx
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// 17/20 times reconnect previous or add a regular tx
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else {
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uint256 prevouthash;
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// equally likely to spend coinbase or non coinbase
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std::set<uint256>::iterator txIt = alltxids.lower_bound(GetRandHash());
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if (txIt == alltxids.end()) {
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txIt = alltxids.begin();
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// 1/20 times reconnect a previously disconnected tx
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if (randiter % 20 == 2 && disconnectedids.size()) {
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TxData &txd = FindRandomFrom(disconnectedids);
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tx = std::get<0>(txd);
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prevouthash = tx.vin[0].prevout.hash;
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if (!CTransaction(tx).IsCoinBase() && !utxoset.count(prevouthash)) {
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disconnectedids.erase(tx.GetHash());
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continue;
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}
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// If this tx is already IN the UTXO, then it must be a coinbase, and it must be a duplicate
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if (utxoset.count(tx.GetHash())) {
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assert(CTransaction(tx).IsCoinBase());
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assert(duplicateids.count(tx.GetHash()));
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}
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disconnectedids.erase(tx.GetHash());
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}
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prevouthash = *txIt;
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// Construct the tx to spend the coins of prevouthash
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tx.vin[0].prevout.hash = prevouthash;
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tx.vin[0].prevout.n = 0;
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// 16/20 times create a regular tx
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else {
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TxData &txd = FindRandomFrom(utxoset);
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prevouthash = std::get<0>(txd).GetHash();
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// Construct the tx to spend the coins of prevouthash
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tx.vin[0].prevout.hash = prevouthash;
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tx.vin[0].prevout.n = 0;
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assert(!CTransaction(tx).IsCoinBase());
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}
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// In this simple test coins only have two states, spent or unspent, save the unspent state to restore
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oldcoins = result[prevouthash];
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// Update the expected result of prevouthash to know these coins are spent
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CCoins& oldcoins = result[prevouthash];
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oldcoins.Clear();
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result[prevouthash].Clear();
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// It is of particular importance here that once we spend a coinbase tx hash
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// it is no longer available to be duplicated (or spent again)
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// BIP 34 in conjunction with enforcing BIP 30 (at least until BIP 34 was active)
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// results in the fact that no coinbases were duplicated after they were already spent
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alltxids.erase(prevouthash);
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coinbaseids.erase(prevouthash);
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utxoset.erase(prevouthash);
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// The test is designed to ensure spending a duplicate coinbase will work properly
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// if that ever happens and not resurrect the previously overwritten coinbase
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if (duplicateids.count(prevouthash))
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spent_a_duplicate_coinbase = true;
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assert(!CTransaction(tx).IsCoinBase());
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}
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// Track this tx to possibly spend later
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alltxids.insert(tx.GetHash());
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// Update the expected result to know about the new output coins
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CCoins &coins = result[tx.GetHash()];
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coins.FromTx(tx, height);
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result[tx.GetHash()].FromTx(tx, height);
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UpdateCoins(tx, *(stack.back()), height);
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// Call UpdateCoins on the top cache
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CTxUndo undo;
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UpdateCoins(tx, *(stack.back()), undo, height);
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// Update the utxo set for future spends
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utxoset.insert(tx.GetHash());
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// Track this tx and undo info to use later
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alltxs.insert(std::make_pair(tx.GetHash(),std::make_tuple(tx,undo,oldcoins)));
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}
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//1/20 times undo a previous transaction
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else if (utxoset.size()) {
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TxData &txd = FindRandomFrom(utxoset);
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CTransaction &tx = std::get<0>(txd);
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CTxUndo &undo = std::get<1>(txd);
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CCoins &origcoins = std::get<2>(txd);
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uint256 undohash = tx.GetHash();
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// Update the expected result
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// Remove new outputs
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result[undohash].Clear();
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// If not coinbase restore prevout
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if (!tx.IsCoinBase()) {
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result[tx.vin[0].prevout.hash] = origcoins;
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}
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// Disconnect the tx from the current UTXO
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// See code in DisconnectBlock
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// remove outputs
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{
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CCoinsModifier outs = stack.back()->ModifyCoins(undohash);
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outs->Clear();
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}
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// restore inputs
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if (!tx.IsCoinBase()) {
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const COutPoint &out = tx.vin[0].prevout;
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const CTxInUndo &undoin = undo.vprevout[0];
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ApplyTxInUndo(undoin, *(stack.back()), out);
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}
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// Store as a candidate for reconnection
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disconnectedids.insert(undohash);
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// Update the utxoset
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utxoset.erase(undohash);
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if (!tx.IsCoinBase())
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utxoset.insert(tx.vin[0].prevout.hash);
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}
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// Once every 1000 iterations and at the end, verify the full cache.
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@ -308,9 +390,9 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
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const CCoins* coins = stack.back()->AccessCoins(it->first);
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if (coins) {
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BOOST_CHECK(*coins == it->second);
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} else {
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} else {
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BOOST_CHECK(it->second.IsPruned());
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}
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}
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}
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}
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@ -334,7 +416,7 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
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tip = stack.back();
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}
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stack.push_back(new CCoinsViewCacheTest(tip));
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}
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}
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}
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}
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@ -420,6 +502,7 @@ BOOST_AUTO_TEST_CASE(ccoins_serialization)
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const static uint256 TXID;
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const static CAmount PRUNED = -1;
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const static CAmount ABSENT = -2;
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const static CAmount FAIL = -3;
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const static CAmount VALUE1 = 100;
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const static CAmount VALUE2 = 200;
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const static CAmount VALUE3 = 300;
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@ -630,11 +713,17 @@ BOOST_AUTO_TEST_CASE(ccoins_modify)
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void CheckModifyNewCoinsBase(CAmount base_value, CAmount cache_value, CAmount modify_value, CAmount expected_value, char cache_flags, char expected_flags, bool coinbase)
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{
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SingleEntryCacheTest test(base_value, cache_value, cache_flags);
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SetCoinsValue(modify_value, *test.cache.ModifyNewCoins(TXID, coinbase));
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CAmount result_value;
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char result_flags;
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GetCoinsMapEntry(test.cache.map(), result_value, result_flags);
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try {
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SetCoinsValue(modify_value, *test.cache.ModifyNewCoins(TXID, coinbase));
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GetCoinsMapEntry(test.cache.map(), result_value, result_flags);
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} catch (std::logic_error& e) {
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result_value = FAIL;
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result_flags = NO_ENTRY;
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}
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BOOST_CHECK_EQUAL(result_value, expected_value);
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BOOST_CHECK_EQUAL(result_flags, expected_flags);
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}
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@ -669,7 +758,7 @@ BOOST_AUTO_TEST_CASE(ccoins_modify_new)
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CheckModifyNewCoins(PRUNED, PRUNED, PRUNED, 0 , DIRTY , true );
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CheckModifyNewCoins(PRUNED, PRUNED, ABSENT, FRESH , NO_ENTRY , false);
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CheckModifyNewCoins(PRUNED, PRUNED, ABSENT, FRESH , NO_ENTRY , true );
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CheckModifyNewCoins(PRUNED, PRUNED, ABSENT, DIRTY , NO_ENTRY , false);
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CheckModifyNewCoins(PRUNED, PRUNED, PRUNED, DIRTY , DIRTY , false);
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CheckModifyNewCoins(PRUNED, PRUNED, PRUNED, DIRTY , DIRTY , true );
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CheckModifyNewCoins(PRUNED, PRUNED, ABSENT, DIRTY|FRESH, NO_ENTRY , false);
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CheckModifyNewCoins(PRUNED, PRUNED, ABSENT, DIRTY|FRESH, NO_ENTRY , true );
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@ -677,25 +766,25 @@ BOOST_AUTO_TEST_CASE(ccoins_modify_new)
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, 0 , DIRTY , true );
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, FRESH , DIRTY|FRESH, false);
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, FRESH , DIRTY|FRESH, true );
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, DIRTY , DIRTY|FRESH, false);
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, DIRTY , DIRTY , false);
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, DIRTY , DIRTY , true );
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, DIRTY|FRESH, DIRTY|FRESH, false);
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CheckModifyNewCoins(PRUNED, VALUE3, VALUE3, DIRTY|FRESH, DIRTY|FRESH, true );
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, 0 , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, FAIL , 0 , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, PRUNED, 0 , DIRTY , true );
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, FRESH , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, FAIL , FRESH , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, FRESH , NO_ENTRY , true );
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, DIRTY , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, FAIL , DIRTY , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, PRUNED, DIRTY , DIRTY , true );
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, DIRTY|FRESH, NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, FAIL , DIRTY|FRESH, NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, PRUNED, ABSENT, DIRTY|FRESH, NO_ENTRY , true );
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, 0 , DIRTY|FRESH, false);
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CheckModifyNewCoins(VALUE2, VALUE3, FAIL , 0 , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, 0 , DIRTY , true );
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, FRESH , DIRTY|FRESH, false);
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CheckModifyNewCoins(VALUE2, VALUE3, FAIL , FRESH , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, FRESH , DIRTY|FRESH, true );
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, DIRTY , DIRTY|FRESH, false);
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CheckModifyNewCoins(VALUE2, VALUE3, FAIL , DIRTY , NO_ENTRY , false);
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CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, DIRTY , DIRTY , true );
|
||||
CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, DIRTY|FRESH, DIRTY|FRESH, false);
|
||||
CheckModifyNewCoins(VALUE2, VALUE3, FAIL , DIRTY|FRESH, NO_ENTRY , false);
|
||||
CheckModifyNewCoins(VALUE2, VALUE3, VALUE3, DIRTY|FRESH, DIRTY|FRESH, true );
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -1499,7 +1499,7 @@ bool AbortNode(CValidationState& state, const std::string& strMessage, const std
|
|||
* @param out The out point that corresponds to the tx input.
|
||||
* @return True on success.
|
||||
*/
|
||||
static bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const COutPoint& out)
|
||||
bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const COutPoint& out)
|
||||
{
|
||||
bool fClean = true;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue