diff options
author | Tom Gundersen <teg@jklm.no> | 2014-01-13 17:30:51 +0100 |
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committer | Tom Gundersen <teg@jklm.no> | 2014-01-13 18:54:19 +0100 |
commit | 6bb648a16ae4a682ad4784412af706d2e6a3e4da (patch) | |
tree | 16e7919cb609b92e879aeeab95c70ce1fc2eb4e2 /src/libsystemd/bus-bloom.c | |
parent | 883b36908788361a8bb945ce884dc518da83b371 (diff) |
libsystemd-bus: rename to libsystemd
Documentation was updated to refer to either 'libsystemd' or 'sd-bus' in place
of libsystemd-bus.
Diffstat (limited to 'src/libsystemd/bus-bloom.c')
-rw-r--r-- | src/libsystemd/bus-bloom.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/src/libsystemd/bus-bloom.c b/src/libsystemd/bus-bloom.c new file mode 100644 index 0000000000..9e51334b52 --- /dev/null +++ b/src/libsystemd/bus-bloom.c @@ -0,0 +1,99 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include "util.h" +#include "siphash24.h" +#include "bus-bloom.h" + +static inline void set_bit(uint64_t filter[], unsigned b) { + filter[b >> 6] |= 1ULL << (b & 63); +} + +#define HASH_KEY1 SD_ID128_MAKE(b9,66,0b,f0,46,70,47,c1,88,75,c4,9c,54,b9,bd,15) +#define HASH_KEY2 SD_ID128_MAKE(aa,a1,54,a2,e0,71,4b,39,bf,e1,dd,2e,9f,c5,4a,3b) + +static void bloom_add_data(uint64_t filter[BLOOM_SIZE/8], const void *data, size_t n) { + uint8_t a[8], b[8]; + unsigned k = 0; + + /* + * Our bloom filter has the following parameters: + * + * m=512 (bits in the filter) + * k=8 (hash functions) + * + * We calculate a two 64bit SipHash values (for two fixed but + * randomly generated hash keys) of which we use 8 parts of 9 bits + * as individual hash functions. + * + */ + + siphash24(a, data, n, HASH_KEY1.bytes); + siphash24(b, data, n, HASH_KEY2.bytes); + + assert_cc(BLOOM_SIZE*8 == 512); + + for (k = 0; k < 8; k++) + set_bit(filter, ((uint16_t) a[k] << 1) ^ (uint16_t) b[k]); + + /* log_debug("bloom: adding <%.*s>", (int) n, (char*) data); */ +} + +void bloom_add_pair(uint64_t filter[BLOOM_SIZE/8], const char *a, const char *b) { + size_t n; + char *c; + + assert(filter); + assert(a); + assert(b); + + n = strlen(a) + 1 + strlen(b); + c = alloca(n + 1); + strcpy(stpcpy(stpcpy(c, a), ":"), b); + + bloom_add_data(filter, c, n); +} + +void bloom_add_prefixes(uint64_t filter[BLOOM_SIZE/8], const char *a, const char *b, char sep) { + size_t n; + char *c, *p; + + assert(filter); + assert(a); + assert(b); + + n = strlen(a) + 1 + strlen(b); + c = alloca(n + 1); + + p = stpcpy(stpcpy(c, a), ":"); + strcpy(p, b); + + for (;;) { + char *e; + + e = strrchr(p, sep); + if (!e || e == p) + break; + + *e = 0; + bloom_add_data(filter, c, e - c); + } +} |