1 files changed, 88 insertions, 0 deletions
diff --git a/src/bloom.h b/src/bloom.h
new file mode 100644
index 0000000000..389ae748e6
--- /dev/null
+++ b/src/bloom.h
@@ -0,0 +1,88 @@
+// 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;
+
+// First two bits of nFlags control how much IsRelevantAndUpdate actually updates
+// The remaining bits are reserved
+enum bloomflags
+{
+    BLOOM_UPDATE_NONE = 0,
+    BLOOM_UPDATE_ALL = 1,
+    // Only adds outpoints to the filter if the output is a pay-to-pubkey/pay-to-multisig script
+    BLOOM_UPDATE_P2PUBKEY_ONLY = 2,
+    BLOOM_UPDATE_MASK = 3,
+};
+
+/**
+ * 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 nTweak;
+    unsigned char nFlags;
+
+    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.
+    // nTweak is a constant which is added to the seed value passed to the hash function
+    // It should generally always be a random value (and is largely only exposed for unit testing)
+    // nFlags should be one of the BLOOM_UPDATE_* enums (not _MASK)
+    CBloomFilter(unsigned int nElements, double nFPRate, unsigned int nTweak, unsigned char nFlagsIn);
+    // Using a filter initialized with this results in undefined behavior
+    // Should only be used for deserialization
+    CBloomFilter() {}
+
+    IMPLEMENT_SERIALIZE
+    (
+        READWRITE(vData);
+        READWRITE(nHashFuncs);
+        READWRITE(nTweak);
+        READWRITE(nFlags);
+    )
+
+    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;
+
+    // Also adds any outputs which match the filter to the filter (to match their spending txes)
+    bool IsRelevantAndUpdate(const CTransaction& tx, const uint256& hash);
+};
+
+#endif /* BITCOIN_BLOOM_H */