diff --git a/node/BloomFilter.hpp b/node/BloomFilter.hpp new file mode 100644 index 000000000..16bd8ee02 --- /dev/null +++ b/node/BloomFilter.hpp @@ -0,0 +1,123 @@ +/* + * ZeroTier One - Global Peer to Peer Ethernet + * Copyright (C) 2012-2013 ZeroTier Networks LLC + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + * + * -- + * + * ZeroTier may be used and distributed under the terms of the GPLv3, which + * are available at: http://www.gnu.org/licenses/gpl-3.0.html + * + * If you would like to embed ZeroTier into a commercial application or + * redistribute it in a modified binary form, please contact ZeroTier Networks + * LLC. Start here: http://www.zerotier.com/ + */ + +#ifndef _ZT_BLOOMFILTER_HPP +#define _ZT_BLOOMFILTER_HPP + +#include +#include "Utils.hpp" + +namespace ZeroTier { + +/** + * A simple bit field bloom filter + * + * This actually isn't a total filter, in that it does not contain a hashing + * algorithm. It's up to the caller to hash/sum the items being remembered + * so that the distribution of 'n' is random. + * + * @tparam B Size in BITS, must be a multiple of 8 + */ +template +class BloomFilter +{ +public: + BloomFilter() + throw() + { + memset(_field,0,sizeof(_field)); + } + + /** + * @return Size of filter in bits + */ + inline unsigned int bits() const throw() { return B; } + + /** + * @return Size of filter in bytes + */ + inline unsigned int bytes() const throw() { return (B / 8); } + + /** + * @return Pointer to portable array of bytes of bytes() length representing filter + */ + inline const unsigned char *data() const throw() { return _field; } + + /** + * Clear all bits in filter + */ + inline void clear() + throw() + { + memset(_field,0,sizeof(_field)); + } + + /** + * @param n Value to set + */ + inline void add(unsigned int n) + throw() + { + n %= B; + _field[n / 8] |= (1 << (n % 8)); + } + + /** + * @param n Value to test + * @return True if value is present is set + */ + inline bool contains(unsigned int n) + throw() + { + n %= B; + return (_field[n / 8] & (1 << (n % 8))); + } + + /** + * Clear one or more random bits + * + * This is used to apply probabilistic decay and hence "fuzziness" to + * a bloom filter over time. + * + * @param bits Number of bits to clear + */ + inline void decay(unsigned int bits) + throw() + { + for(unsigned int i=0;i(); + _field[(rn >> 7) % (B / 8)] &= ~((unsigned char)(1 << (rn & 7))); + } + } + +private: + unsigned char _field[B / 8]; +}; + +} // namespace ZeroTier + +#endif diff --git a/node/Utils.hpp b/node/Utils.hpp index 5cdf10def..4b7d6be88 100644 --- a/node/Utils.hpp +++ b/node/Utils.hpp @@ -460,38 +460,6 @@ public: return ((*aptr & mask) == (*aptr & mask)); } - /** - * Add a value to a bloom filter - * - * Note that bloom filter methods depend on n being evenly distributed, so - * it's the job of the caller to implement any hashing. - * - * @param bits Bloom filter data (must be filterSize / 8 bytes in length) - * @param filterSize Size of bloom filter in BITS - * @param n Number to add - */ - static inline void bloomAdd(void *bits,unsigned int filterSize,unsigned int n) - throw() - { - n %= filterSize; - ((unsigned char *)bits)[n / 8] |= (0x80 >> (n % 8)); - } - - /** - * Test for a value in a bloom filter - * - * @param bits Bloom filter data (must be filterSize / 8 bytes in length) - * @param filterSize Size of bloom filter in BITS - * @param n Number to test - * @return True if number might be in filter - */ - static inline bool bloomContains(const void *bits,unsigned int filterSize,unsigned int n) - throw() - { - n %= filterSize; - return ((((const unsigned char *)bits)[n / 8] & (0x80 >> (n % 8)))); - } - /** * Compute CRC64 *