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BRBloomFilter.h
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BRBloomFilter.h
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//
// BRBloomFilter.h
//
// Created by Aaron Voisine on 9/2/15.
// Copyright (c) 2015 breadwallet LLC.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#ifndef BRBloomFilter_h
#define BRBloomFilter_h
#include <stddef.h>
#include <inttypes.h>
#ifdef __cplusplus
extern "C" {
#endif
// bloom filters are explained in BIP37: https://github.com/bitcoin/bips/blob/master/bip-0037.mediawiki
#define BLOOM_DEFAULT_FALSEPOSITIVE_RATE 0.0005 // use 0.00005 for less data, 0.001 for good anonymity
#define BLOOM_REDUCED_FALSEPOSITIVE_RATE 0.00005
#define BLOOM_UPDATE_NONE 0
#define BLOOM_UPDATE_ALL 1
#define BLOOM_UPDATE_P2PUBKEY_ONLY 2
#define BLOOM_MAX_FILTER_LENGTH 36000 // this allows for 10,000 elements with a <0.0001% false positive rate
typedef struct {
uint8_t *filter;
size_t length;
uint32_t hashFuncs;
size_t elemCount;
uint32_t tweak;
uint8_t flags;
} BRBloomFilter;
// a bloom filter that matches everything is useful if a full node wants to use the filtered block protocol, which
// doesn't send transactions with blocks if the receiving node already received the tx prior to its inclusion in the
// block, allowing a full node to operate while using about half the network traffic
#define BR_BLOOM_FILTER_FULL ((BRBloomFilter) { &((struct { uint8_t u; }) { 0xff }).u, 1, 0, 0, 0, BLOOM_UPDATE_NONE })
// returns a newly allocated bloom filter struct that must be freed by calling BRBloomFilterFree()
BRBloomFilter *BRBloomFilterNew(double falsePositiveRate, size_t elemCount, uint32_t tweak, uint8_t flags);
// buf must contain a serialized filter
// returns a bloom filter struct that must be freed by calling BRBloomFilterFree()
BRBloomFilter *BRBloomFilterParse(const uint8_t *buf, size_t bufLen);
// returns number of bytes written to buf, or total bufLen needed if buf is NULL
size_t BRBloomFilterSerialize(const BRBloomFilter *filter, uint8_t *buf, size_t bufLen);
// true if data is matched by filter
int BRBloomFilterContainsData(const BRBloomFilter *filter, const uint8_t *data, size_t dataLen);
// add data to filter
void BRBloomFilterInsertData(BRBloomFilter *filter, const uint8_t *data, size_t dataLen);
// frees memory allocated for filter
void BRBloomFilterFree(BRBloomFilter *filter);
#ifdef __cplusplus
}
#endif
#endif // BRBloomFilter_h