1 files changed, 272 insertions, 0 deletions
diff --git a/src/bloom.cpp b/src/bloom.cpp
new file mode 100644
index 000000000..de8720659
--- /dev/null
+++ b/src/bloom.cpp
@@ -0,0 +1,272 @@
+// Copyright (c) 2012-2014 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 "bloom.h"
+
+#include "primitives/transaction.h"
+#include "hash.h"
+#include "script/script.h"
+#include "script/standard.h"
+#include "random.h"
+#include "streams.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+#include <boost/foreach.hpp>
+
+#define LN2SQUARED 0.4804530139182014246671025263266649717305529515945455
+#define LN2 0.6931471805599453094172321214581765680755001343602552
+
+using namespace std;
+
+CBloomFilter::CBloomFilter(unsigned int nElements, double nFPRate, unsigned int nTweakIn, unsigned char nFlagsIn) :
+    /**
+     * The ideal size for a bloom filter with a given number of elements and false positive rate is:
+     * - nElements * log(fp rate) / ln(2)^2
+     * We ignore filter parameters which will create a bloom filter larger than the protocol limits
+     */
+    vData(min((unsigned int)(-1  / LN2SQUARED * nElements * log(nFPRate)), MAX_BLOOM_FILTER_SIZE * 8) / 8),
+    /**
+     * The ideal number of hash functions is filter size * ln(2) / number of elements
+     * 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(false),
+    nHashFuncs(min((unsigned int)(vData.size() * 8 / nElements * LN2), MAX_HASH_FUNCS)),
+    nTweak(nTweakIn),
+    nFlags(nFlagsIn)
+{
+}
+
+// Private constructor used by CRollingBloomFilter
+CBloomFilter::CBloomFilter(unsigned int nElements, double nFPRate, unsigned int nTweakIn) :
+    vData((unsigned int)(-1  / LN2SQUARED * nElements * log(nFPRate)) / 8),
+    isFull(false),
+    isEmpty(true),
+    nHashFuncs((unsigned int)(vData.size() * 8 / nElements * LN2)),
+    nTweak(nTweakIn),
+    nFlags(BLOOM_UPDATE_NONE)
+{
+}
+
+inline unsigned int CBloomFilter::Hash(unsigned int nHashNum, const std::vector<unsigned char>& vDataToHash) const
+{
+    // 0xFBA4C795 chosen as it guarantees a reasonable bit difference between nHashNum values.
+    return MurmurHash3(nHashNum * 0xFBA4C795 + nTweak, vDataToHash) % (vData.size() * 8);
+}
+
+void CBloomFilter::insert(const vector<unsigned char>& vKey)
+{
+    if (isFull)
+        return;
+    for (unsigned int i = 0; i < nHashFuncs; i++)
+    {
+        unsigned int nIndex = Hash(i, vKey);
+        // Sets bit nIndex of vData
+        vData[nIndex >> 3] |= (1 << (7 & nIndex));
+    }
+    isEmpty = false;
+}
+
+void CBloomFilter::insert(const COutPoint& outpoint)
+{
+    CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
+    stream << outpoint;
+    vector<unsigned char> data(stream.begin(), stream.end());
+    insert(data);
+}
+
+void CBloomFilter::insert(const uint256& hash)
+{
+    vector<unsigned char> data(hash.begin(), hash.end());
+    insert(data);
+}
+
+bool CBloomFilter::contains(const vector<unsigned char>& vKey) const
+{
+    if (isFull)
+        return true;
+    if (isEmpty)
+        return false;
+    for (unsigned int i = 0; i < nHashFuncs; i++)
+    {
+        unsigned int nIndex = Hash(i, vKey);
+        // Checks bit nIndex of vData
+        if (!(vData[nIndex >> 3] & (1 << (7 & nIndex))))
+            return false;
+    }
+    return true;
+}
+
+bool CBloomFilter::contains(const COutPoint& outpoint) const
+{
+    CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
+    stream << outpoint;
+    vector<unsigned char> data(stream.begin(), stream.end());
+    return contains(data);
+}
+
+bool CBloomFilter::contains(const uint256& hash) const
+{
+    vector<unsigned char> data(hash.begin(), hash.end());
+    return contains(data);
+}
+
+void CBloomFilter::clear()
+{
+    vData.assign(vData.size(),0);
+    isFull = false;
+    isEmpty = true;
+}
+
+void CBloomFilter::reset(unsigned int nNewTweak)
+{
+    clear();
+    nTweak = nNewTweak;
+}
+
+bool CBloomFilter::IsWithinSizeConstraints() const
+{
+    return vData.size() <= MAX_BLOOM_FILTER_SIZE && nHashFuncs <= MAX_HASH_FUNCS;
+}
+
+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)
+        return true;
+    if (isEmpty)
+        return false;
+    const uint256& hash = tx.GetHash();
+    if (contains(hash))
+        fFound = true;
+
+    for (unsigned int i = 0; i < tx.vout.size(); i++)
+    {
+        const CTxOut& txout = tx.vout[i];
+        // Match if the filter contains any arbitrary script data element in any scriptPubKey in tx
+        // If this matches, also add the specific output that was matched.
+        // This means clients don't have to update the filter themselves when a new relevant tx 
+        // is discovered in order to find spending transactions, which avoids round-tripping and race conditions.
+        CScript::const_iterator pc = txout.scriptPubKey.begin();
+        vector<unsigned char> data;
+        while (pc < txout.scriptPubKey.end())
+        {
+            opcodetype opcode;
+            if (!txout.scriptPubKey.GetOp(pc, opcode, data))
+                break;
+            if (data.size() != 0 && contains(data))
+            {
+                fFound = true;
+                if ((nFlags & BLOOM_UPDATE_MASK) == BLOOM_UPDATE_ALL)
+                    insert(COutPoint(hash, i));
+                else if ((nFlags & BLOOM_UPDATE_MASK) == BLOOM_UPDATE_P2PUBKEY_ONLY)
+                {
+                    txnouttype type;
+                    vector<vector<unsigned char> > vSolutions;
+                    if (Solver(txout.scriptPubKey, type, vSolutions) &&
+                            (type == TX_PUBKEY || type == TX_MULTISIG))
+                        insert(COutPoint(hash, i));
+                }
+                break;
+            }
+        }
+    }
+
+    if (fFound)
+        return true;
+
+    BOOST_FOREACH(const CTxIn& txin, tx.vin)
+    {
+        // Match if the filter contains an outpoint tx spends
+        if (contains(txin.prevout))
+            return true;
+
+        // Match if the filter contains any arbitrary script data element in any scriptSig in tx
+        CScript::const_iterator pc = txin.scriptSig.begin();
+        vector<unsigned char> data;
+        while (pc < txin.scriptSig.end())
+        {
+            opcodetype opcode;
+            if (!txin.scriptSig.GetOp(pc, opcode, data))
+                break;
+            if (data.size() != 0 && contains(data))
+                return true;
+        }
+    }
+
+    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(unsigned int nElements, double fpRate) :
+    b1(nElements * 2, fpRate, 0), b2(nElements * 2, fpRate, 0)
+{
+    // Implemented using two bloom filters of 2 * nElements each.
+    // We fill them up, and clear them, staggered, every nElements
+    // inserted, so at least one always contains the last nElements
+    // inserted.
+    nInsertions = 0;
+    nBloomSize = nElements * 2;
+
+    reset();
+}
+
+void CRollingBloomFilter::insert(const std::vector<unsigned char>& vKey)
+{
+    if (nInsertions == 0) {
+        b1.clear();
+    } else if (nInsertions == nBloomSize / 2) {
+        b2.clear();
+    }
+    b1.insert(vKey);
+    b2.insert(vKey);
+    if (++nInsertions == nBloomSize) {
+        nInsertions = 0;
+    }
+}
+
+void CRollingBloomFilter::insert(const uint256& hash)
+{
+    vector<unsigned char> data(hash.begin(), hash.end());
+    insert(data);
+}
+
+bool CRollingBloomFilter::contains(const std::vector<unsigned char>& vKey) const
+{
+    if (nInsertions < nBloomSize / 2) {
+        return b2.contains(vKey);
+    }
+    return b1.contains(vKey);
+}
+
+bool CRollingBloomFilter::contains(const uint256& hash) const
+{
+    vector<unsigned char> data(hash.begin(), hash.end());
+    return contains(data);
+}
+
+void CRollingBloomFilter::reset()
+{
+    unsigned int nNewTweak = GetRand(std::numeric_limits<unsigned int>::max());
+    b1.reset(nNewTweak);
+    b2.reset(nNewTweak);
+    nInsertions = 0;
+}