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/* Copyright (c) 2014, Vsevolod Stakhov
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "shingles.h"
#include "fstring.h"
#include "siphash.h"
#define SHINGLES_WINDOW 10
static void
rspamd_shingles_update_row (rspamd_fstring_t *in, struct siphash *h)
{
int i;
for (i = 0; i < RSPAMD_SHINGLE_SIZE; i ++) {
sip24_update (&h[i], in->begin, in->len);
}
}
struct rspamd_shingle*
rspamd_shingles_generate (GArray *input,
const guchar key[16],
rspamd_mempool_t *pool,
rspamd_shingles_filter filter,
gpointer filterd)
{
struct rspamd_shingle *res;
GArray *hashes[RSPAMD_SHINGLE_SIZE];
struct sipkey keys[RSPAMD_SHINGLE_SIZE];
struct siphash h[RSPAMD_SHINGLE_SIZE];
guchar shabuf[32], *out_key;
const guchar *cur_key;
GChecksum *cksum;
gint i, j, beg = 0;
gsize shalen;
if (pool != NULL) {
res = rspamd_mempool_alloc (pool, sizeof (*res));
}
else {
res = g_malloc (sizeof (*res));
}
cksum = g_checksum_new (G_CHECKSUM_SHA256);
cur_key = key;
out_key = (guchar *)&keys[0];
/* Init hashes pipes and keys */
for (i = 0; i < RSPAMD_SHINGLE_SIZE; i ++) {
hashes[i] = g_array_sized_new (FALSE, FALSE, sizeof (guint64),
SHINGLES_WINDOW * 2);
/*
* To generate a set of hashes we just apply sha256 to the
* initial key as many times as many hashes are required and
* xor left and right parts of sha256 to get a single 16 bytes SIP key.
*/
shalen = sizeof (shabuf);
g_checksum_update (cksum, cur_key, 16);
g_checksum_get_digest (cksum, shabuf, &shalen);
for (j = 0; j < 16; j ++) {
out_key[j] = shabuf[j] ^ shabuf[sizeof(shabuf) - j - 1];
}
g_checksum_reset (cksum);
cur_key = out_key;
out_key += 16;
sip24_init (&h[i], &keys[i]);
}
g_checksum_free (cksum);
/* Now parse input words into a vector of hashes using rolling window */
for (i = 0; i < (gint)input->len; i ++) {
if (i - beg >= SHINGLES_WINDOW || i == (gint)input->len - 1) {
for (j = beg; j <= i; j ++) {
rspamd_shingles_update_row (&g_array_index (input,
rspamd_fstring_t, j), h);
}
/* Now we need to create a new row here */
for (j = 0; j < RSPAMD_SHINGLE_SIZE; j ++) {
guint64 val;
val = sip24_final (&h[i]);
/* Reinit siphash state */
sip24_init (&h[i], &keys[i]);
g_array_append_val (hashes[i], val);
}
}
}
/* Now we need to filter all hashes and make a shingles result */
for (i = 0; i < RSPAMD_SHINGLE_SIZE; i ++) {
res->hashes[i] = filter ((guint64 *)hashes[i]->data, hashes[i]->len,
filterd);
g_array_free (hashes[i], TRUE);
}
return res;
}
guint64
rspamd_shingles_default_filter (guint64 *input, gsize count,
gpointer ud)
{
guint64 minimal = G_MAXUINT64;
gsize i;
for (i = 0; i < count; i ++) {
if (minimal > input[i]) {
minimal = input[i];
}
}
return minimal;
}
gdouble rspamd_shingles_compare (const struct rspamd_shingle *a,
const struct rspamd_shingle *b)
{
gint i, common = 0;
for (i = 0; i < RSPAMD_SHINGLE_SIZE; i ++) {
if (a->hashes[i] == b->hashes[i]) {
common ++;
}
}
return (gdouble)common / 84.0;
}
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