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-rw-r--r--src/bloom.cpp133
-rw-r--r--src/bloom.h70
-rw-r--r--src/makefile.linux-mingw1
-rw-r--r--src/makefile.mingw1
-rw-r--r--src/makefile.osx1
-rw-r--r--src/makefile.unix1
6 files changed, 207 insertions, 0 deletions
diff --git a/src/bloom.cpp b/src/bloom.cpp
new file mode 100644
index 0000000000..5fac1d06ab
--- /dev/null
+++ b/src/bloom.cpp
@@ -0,0 +1,133 @@
+// Copyright (c) 2012 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#include <math.h>
+#include <stdlib.h>
+
+#include "bloom.h"
+#include "main.h"
+#include "script.h"
+
+#define LN2SQUARED 0.4804530139182014246671025263266649717305529515945455
+#define LN2 0.6931471805599453094172321214581765680755001343602552
+
+using namespace std;
+
+static const unsigned char bit_mask[8] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};
+
+CBloomFilter::CBloomFilter(unsigned int nElements, double nFPRate) :
+// 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 http://en.wikipedia.org/wiki/Bloom_filter for an explanation of these formulas
+nHashFuncs(min((unsigned int)(vData.size() * 8 / nElements * LN2), MAX_HASH_FUNCS))
+{
+}
+
+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, vDataToHash) % (vData.size() * 8);
+}
+
+void CBloomFilter::insert(const vector<unsigned char>& vKey)
+{
+ for (unsigned int i = 0; i < nHashFuncs; i++)
+ {
+ unsigned int nIndex = Hash(i, vKey);
+ // Sets bit nIndex of vData
+ vData[nIndex >> 3] |= bit_mask[7 & nIndex];
+ }
+}
+
+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
+{
+ for (unsigned int i = 0; i < nHashFuncs; i++)
+ {
+ unsigned int nIndex = Hash(i, vKey);
+ // Checks bit nIndex of vData
+ if (!(vData[nIndex >> 3] & bit_mask[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);
+}
+
+bool CBloomFilter::IsWithinSizeConstraints() const
+{
+ return vData.size() <= MAX_BLOOM_FILTER_SIZE && nHashFuncs <= MAX_HASH_FUNCS;
+}
+
+bool CBloomFilter::IsTransactionRelevantToFilter(const CTransaction& tx) const
+{
+ // Match if the filter contains the hash of tx
+ // for finding tx when they appear in a block
+ if (contains(tx.GetHash()))
+ return true;
+
+ BOOST_FOREACH(const CTxOut& txout, tx.vout)
+ {
+ // Match if the filter contains any arbitrary script data element in any scriptPubKey in tx
+ 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))
+ 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;
+}
diff --git a/src/bloom.h b/src/bloom.h
new file mode 100644
index 0000000000..ce84e66552
--- /dev/null
+++ b/src/bloom.h
@@ -0,0 +1,70 @@
+// Copyright (c) 2012 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#ifndef BITCOIN_BLOOM_H
+#define BITCOIN_BLOOM_H
+
+#include <vector>
+
+#include "uint256.h"
+#include "serialize.h"
+
+class COutPoint;
+class CTransaction;
+
+// 20,000 items with fp rate < 0.1% or 10,000 items and <0.0001%
+static const unsigned int MAX_BLOOM_FILTER_SIZE = 36000; // bytes
+static const unsigned int MAX_HASH_FUNCS = 50;
+
+
+/**
+ * BloomFilter is a probabilistic filter which SPV clients provide
+ * so that we can filter the transactions we sends them.
+ *
+ * This allows for significantly more efficient transaction and block downloads.
+ *
+ * Because bloom filters are probabilistic, an SPV node can increase the false-
+ * positive rate, making us send them transactions which aren't actually theirs,
+ * allowing clients to trade more bandwidth for more privacy by obfuscating which
+ * keys are owned by them.
+ */
+class CBloomFilter
+{
+private:
+ std::vector<unsigned char> vData;
+ unsigned int nHashFuncs;
+
+ unsigned int Hash(unsigned int nHashNum, const std::vector<unsigned char>& vDataToHash) const;
+
+public:
+ // Creates a new bloom filter which will provide the given fp rate when filled with the given number of elements
+ // Note that if the given parameters will result in a filter outside the bounds of the protocol limits,
+ // the filter created will be as close to the given parameters as possible within the protocol limits.
+ // This will apply if nFPRate is very low or nElements is unreasonably high.
+ CBloomFilter(unsigned int nElements, double nFPRate);
+ // Using a filter initialized with this results in undefined behavior
+ // Should only be used for deserialization
+ CBloomFilter() {}
+
+ IMPLEMENT_SERIALIZE
+ (
+ READWRITE(vData);
+ READWRITE(nHashFuncs);
+ )
+
+ void insert(const std::vector<unsigned char>& vKey);
+ void insert(const COutPoint& outpoint);
+ void insert(const uint256& hash);
+
+ bool contains(const std::vector<unsigned char>& vKey) const;
+ bool contains(const COutPoint& outpoint) const;
+ bool contains(const uint256& hash) const;
+
+ // True if the size is <= MAX_BLOOM_FILTER_SIZE and the number of hash functions is <= MAX_HASH_FUNCS
+ // (catch a filter which was just deserialized which was too big)
+ bool IsWithinSizeConstraints() const;
+
+ bool IsTransactionRelevantToFilter(const CTransaction& tx) const;
+};
+
+#endif /* BITCOIN_BLOOM_H */
diff --git a/src/makefile.linux-mingw b/src/makefile.linux-mingw
index 95e7e83cd0..ff565f2a2d 100644
--- a/src/makefile.linux-mingw
+++ b/src/makefile.linux-mingw
@@ -84,6 +84,7 @@ OBJS= \
obj/walletdb.o \
obj/noui.o \
obj/hash.o \
+ obj/bloom.o \
obj/leveldb.o \
obj/txdb.o
diff --git a/src/makefile.mingw b/src/makefile.mingw
index 2abc34478d..9a6680bf40 100644
--- a/src/makefile.mingw
+++ b/src/makefile.mingw
@@ -79,6 +79,7 @@ OBJS= \
obj/wallet.o \
obj/walletdb.o \
obj/hash.o \
+ obj/bloom.o \
obj/noui.o \
obj/leveldb.o \
obj/txdb.o
diff --git a/src/makefile.osx b/src/makefile.osx
index 474f17b735..8b7c559fa1 100644
--- a/src/makefile.osx
+++ b/src/makefile.osx
@@ -97,6 +97,7 @@ OBJS= \
obj/wallet.o \
obj/walletdb.o \
obj/hash.o \
+ obj/bloom.o \
obj/noui.o \
obj/leveldb.o \
obj/txdb.o
diff --git a/src/makefile.unix b/src/makefile.unix
index 979a4a6520..14cf1b8fa5 100644
--- a/src/makefile.unix
+++ b/src/makefile.unix
@@ -128,6 +128,7 @@ OBJS= \
obj/wallet.o \
obj/walletdb.o \
obj/hash.o \
+ obj/bloom.o \
obj/noui.o \
obj/leveldb.o \
obj/txdb.o