/*-*- 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 long b) { filter[b >> 6] |= 1ULL << (b & 63); } static const sd_id128_t hash_keys[] = { SD_ID128_ARRAY(b9,66,0b,f0,46,70,47,c1,88,75,c4,9c,54,b9,bd,15), SD_ID128_ARRAY(aa,a1,54,a2,e0,71,4b,39,bf,e1,dd,2e,9f,c5,4a,3b), SD_ID128_ARRAY(63,fd,ae,be,cd,82,48,12,a1,6e,41,26,cb,fa,a0,c8), SD_ID128_ARRAY(23,be,45,29,32,d2,46,2d,82,03,52,28,fe,37,17,f5), SD_ID128_ARRAY(56,3b,bf,ee,5a,4f,43,39,af,aa,94,08,df,f0,fc,10), SD_ID128_ARRAY(31,80,c8,73,c7,ea,46,d3,aa,25,75,0f,9e,4c,09,29), SD_ID128_ARRAY(7d,f7,18,4b,7b,a4,44,d5,85,3c,06,e0,65,53,96,6d), SD_ID128_ARRAY(f2,77,e9,6f,93,b5,4e,71,9a,0c,34,88,39,25,bf,35), }; static void bloom_add_data( uint64_t filter[], /* The filter bits */ size_t size, /* Size of the filter in bytes */ unsigned k, /* Number of hash functions */ const void *data, /* Data to hash */ size_t n) { /* Size of data to hash in bytes */ uint8_t h[8]; uint64_t m; unsigned w, i, c = 0; assert(size > 0); assert(k > 0); /* Determine bits in filter */ m = size * 8; /* Determine how many bytes we need to generate a bit index 0..m for this filter */ w = (u64log2(m) + 7) / 8; assert(w <= sizeof(uint64_t)); /* Make sure we have enough hash keys to generate m * k bits * of hash value. Note that SipHash24 generates 64 bits of * hash value for each 128 bits of hash key. */ assert(k * w <= ELEMENTSOF(hash_keys) * 8); for (i = 0; i < k; i++) { uint64_t p = 0; unsigned d; for (d = 0; d < w; d++) { if (c <= 0) { siphash24(h, data, n, hash_keys[i++].bytes); c += 8; } p = (p << 8ULL) | (uint64_t) h[8 - c]; c--; } p &= m - 1; set_bit(filter, p); } /* log_debug("bloom: adding <%.*s>", (int) n, (char*) data); */ } void bloom_add_pair(uint64_t filter[], size_t size, unsigned k, 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, size, k, c, n); } void bloom_add_prefixes(uint64_t filter[], size_t size, unsigned k, 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, size, k, c, e - c); } } bool bloom_validate_parameters(size_t size, unsigned k) { uint64_t m; unsigned w; if (size <= 0) return false; if (k <= 0) return false; m = size * 8; w = (u64log2(m) + 7) / 8; if (w > sizeof(uint64_t)) return false; if (k * w > ELEMENTSOF(hash_keys) * 8) return false; return true; }