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/*-
* Copyright 2016 Vsevolod Stakhov
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "shingles.h"
#include "fstring.h"
#include "cryptobox.h"
#define SHINGLES_WINDOW 3
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];
rspamd_sipkey_t keys[RSPAMD_SHINGLE_SIZE];
guchar shabuf[rspamd_cryptobox_HASHBYTES], *out_key;
const guchar *cur_key;
rspamd_fstring_t *row;
rspamd_ftok_t *word;
rspamd_cryptobox_hash_state_t bs;
guint64 val;
gint i, j, beg = 0;
if (pool != NULL) {
res = rspamd_mempool_alloc (pool, sizeof (*res));
}
else {
res = g_malloc (sizeof (*res));
}
rspamd_cryptobox_hash_init (&bs, NULL, 0);
row = rspamd_fstring_sized_new (256);
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),
input->len + SHINGLES_WINDOW);
/*
* 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.
*/
rspamd_cryptobox_hash_update (&bs, cur_key, 16);
rspamd_cryptobox_hash_final (&bs, shabuf);
for (j = 0; j < 16; j ++) {
out_key[j] = shabuf[j];
}
rspamd_cryptobox_hash_init (&bs, NULL, 0);
cur_key = out_key;
out_key += 16;
}
/* 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) {
for (j = beg; j < i; j ++) {
word = &g_array_index (input, rspamd_ftok_t, j);
row = rspamd_fstring_append (row, word->begin, word->len);
}
beg++;
/* Now we need to create a new row here */
for (j = 0; j < RSPAMD_SHINGLE_SIZE; j ++) {
rspamd_cryptobox_siphash ((guchar *)&val, row->str, row->len,
keys[j]);
g_array_append_val (hashes[j], val);
}
row = rspamd_fstring_assign (row, "", 0);
}
}
/* 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,
i, key, filterd);
g_array_free (hashes[i], TRUE);
}
rspamd_fstring_free (row);
return res;
}
guint64
rspamd_shingles_default_filter (guint64 *input, gsize count,
gint shno, const guchar *key, 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 / (gdouble)RSPAMD_SHINGLE_SIZE;
}
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