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authorTom Gundersen <teg@jklm.no>2014-01-13 17:30:51 +0100
committerTom Gundersen <teg@jklm.no>2014-01-13 18:54:19 +0100
commit6bb648a16ae4a682ad4784412af706d2e6a3e4da (patch)
tree16e7919cb609b92e879aeeab95c70ce1fc2eb4e2 /src/libsystemd/bus-bloom.c
parent883b36908788361a8bb945ce884dc518da83b371 (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.c99
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);
+ }
+}