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net: remove is{Empty,Full} flags from CBloomFilter, clarify CVE fix 

(cherry picked from commit 1ad8ea2b73134bdd8d6b50704a019d47ad2191d8)

Zcash: Excluding change to src/test/fuzz/bloom_filter.cpp which we
don't have (we haven't backported upstream's fuzzing framework).
This commit is contained in:
Sebastian Falbesoner 2020-04-28 19:19:34 +02:00 committed by Jack Grigg
parent 48fe1baf00
commit 3e0ef7ffbb
3 changed files with 4 additions and 30 deletions
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26
src/bloom.cpp
View File

@ -31,8 +31,6 @@ CBloomFilter::CBloomFilter(const unsigned int nElements, const double nFPRate, c
* Again, we ignore filter parameters which will create a bloom filter with more hash functions than the protocol limits
* See https://en.wikipedia.org/wiki/Bloom_filter for an explanation of these formulas
*/
isFull(false),
isEmpty(true),
nHashFuncs(std::min((unsigned int)(vData.size() * 8 / nElements * LN2), MAX_HASH_FUNCS)),
nTweak(nTweakIn),
nFlags(nFlagsIn)
@ -47,7 +45,7 @@ inline unsigned int CBloomFilter::Hash(unsigned int nHashNum, const std::vector<
void CBloomFilter::insert(const std::vector<unsigned char>& vKey)
{
if (isFull)
if (vData.empty()) // Avoid divide-by-zero (CVE-2013-5700)
return;
for (unsigned int i = 0; i < nHashFuncs; i++)
{
@ -55,7 +53,6 @@ void CBloomFilter::insert(const std::vector<unsigned char>& vKey)
// Sets bit nIndex of vData
vData[nIndex >> 3] |= (1 << (7 & nIndex));
}
isEmpty = false;
}
void CBloomFilter::insert(const COutPoint& outpoint)
@ -74,10 +71,8 @@ void CBloomFilter::insert(const uint256& hash)
bool CBloomFilter::contains(const std::vector<unsigned char>& vKey) const
{
if (isFull)
if (vData.empty()) // Avoid divide-by-zero (CVE-2013-5700)
return true;
if (isEmpty)
return false;
for (unsigned int i = 0; i < nHashFuncs; i++)
{
unsigned int nIndex = Hash(i, vKey);
@ -112,10 +107,8 @@ bool CBloomFilter::IsRelevantAndUpdate(const CTransaction& tx)
bool fFound = false;
// Match if the filter contains the hash of tx
// for finding tx when they appear in a block
if (isFull)
if (vData.empty()) // zero-size = "match-all" filter
return true;
if (isEmpty)
return false;
const uint256& hash = tx.GetHash();
if (contains(hash))
fFound = true;
@ -177,19 +170,6 @@ bool CBloomFilter::IsRelevantAndUpdate(const CTransaction& tx)
return false;
}
void CBloomFilter::UpdateEmptyFull()
{
bool full = true;
bool empty = true;
for (unsigned int i = 0; i < vData.size(); i++)
{
full &= vData[i] == 0xff;
empty &= vData[i] == 0;
}
isFull = full;
isEmpty = empty;
}
CRollingBloomFilter::CRollingBloomFilter(const unsigned int nElements, const double fpRate)
{
double logFpRate = log(fpRate);

7
src/bloom.h
View File

@ -45,8 +45,6 @@ class CBloomFilter
{
private:
std::vector<unsigned char> vData;
bool isFull;
bool isEmpty;
unsigned int nHashFuncs;
unsigned int nTweak;
unsigned char nFlags;
@ -64,7 +62,7 @@ public:
* nFlags should be one of the BLOOM_UPDATE_* enums (not _MASK)
*/
CBloomFilter(const unsigned int nElements, const double nFPRate, const unsigned int nTweak, unsigned char nFlagsIn);
CBloomFilter() : isFull(true), isEmpty(false), nHashFuncs(0), nTweak(0), nFlags(0) {}
CBloomFilter() : nHashFuncs(0), nTweak(0), nFlags(0) {}
ADD_SERIALIZE_METHODS;
@ -90,9 +88,6 @@ public:
//! Also adds any outputs which match the filter to the filter (to match their spending txes)
bool IsRelevantAndUpdate(const CTransaction& tx);
//! Checks for empty and full filters to avoid wasting cpu
void UpdateEmptyFull();
};
/**

1
src/main.cpp
View File

@ -6595,7 +6595,6 @@ bool static ProcessMessage(const CChainParams& chainparams, CNode* pfrom, string
LOCK(pfrom->cs_filter);
delete pfrom->pfilter;
pfrom->pfilter = new CBloomFilter(filter);
pfrom->pfilter->UpdateEmptyFull();
pfrom->fRelayTxes = true;
}
}