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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.
*/
/***MODULE:chartable
* rspamd module that make marks based on symbol chains
*
* Allowed options:
* - symbol (string): symbol to insert (default: 'R_BAD_CHARSET')
* - threshold (double): value that would be used as threshold in expression characters_changed / total_characters
* (e.g. if threshold is 0.1 than charset change should occure more often than in 10 symbols), default: 0.1
*/
#include "config.h"
#include "libmime/message.h"
#include "rspamd.h"
#define DEFAULT_SYMBOL "R_CHARSET_MIXED"
#define DEFAULT_THRESHOLD 0.1
/* Initialization */
gint chartable_module_init (struct rspamd_config *cfg, struct module_ctx **ctx);
gint chartable_module_config (struct rspamd_config *cfg);
gint chartable_module_reconfig (struct rspamd_config *cfg);
module_t chartable_module = {
"chartable",
chartable_module_init,
chartable_module_config,
chartable_module_reconfig,
NULL
};
struct chartable_ctx {
struct module_ctx ctx;
const gchar *symbol;
double threshold;
rspamd_mempool_t *chartable_pool;
};
static struct chartable_ctx *chartable_module_ctx = NULL;
static void chartable_symbol_callback (struct rspamd_task *task, void *unused);
gint
chartable_module_init (struct rspamd_config *cfg, struct module_ctx **ctx)
{
chartable_module_ctx = g_malloc (sizeof (struct chartable_ctx));
chartable_module_ctx->chartable_pool = rspamd_mempool_new (rspamd_mempool_suggest_size (), NULL);
*ctx = (struct module_ctx *)chartable_module_ctx;
return 0;
}
gint
chartable_module_config (struct rspamd_config *cfg)
{
const ucl_object_t *value;
gint res = TRUE;
if (!rspamd_config_is_module_enabled (cfg, "chartable")) {
return TRUE;
}
if ((value =
rspamd_config_get_module_opt (cfg, "chartable", "symbol")) != NULL) {
chartable_module_ctx->symbol = ucl_obj_tostring (value);
}
else {
chartable_module_ctx->symbol = DEFAULT_SYMBOL;
}
if ((value =
rspamd_config_get_module_opt (cfg, "chartable", "threshold")) != NULL) {
if (!ucl_obj_todouble_safe (value, &chartable_module_ctx->threshold)) {
msg_warn_config ("invalid numeric value");
chartable_module_ctx->threshold = DEFAULT_THRESHOLD;
}
}
else {
chartable_module_ctx->threshold = DEFAULT_THRESHOLD;
}
rspamd_symbols_cache_add_symbol (cfg->cache,
chartable_module_ctx->symbol,
0,
chartable_symbol_callback,
NULL,
SYMBOL_TYPE_NORMAL,
-1);
msg_info_config ("init internal chartable module");
return res;
}
gint
chartable_module_reconfig (struct rspamd_config *cfg)
{
rspamd_mempool_delete (chartable_module_ctx->chartable_pool);
chartable_module_ctx->chartable_pool = rspamd_mempool_new (1024, NULL);
return chartable_module_config (cfg);
}
static gboolean
check_part (struct mime_text_part *part, gboolean raw_mode)
{
guchar *p, *p1;
gunichar c, t;
GUnicodeScript scc, sct;
guint32 mark = 0, total = 0, max = 0, i;
guint32 remain = part->content->len;
guint32 scripts[G_UNICODE_SCRIPT_NKO];
GUnicodeScript sel = 0;
p = part->content->data;
if (IS_PART_UTF (part) || raw_mode) {
while (remain > 1) {
if ((g_ascii_isalpha (*p) &&
(*(p + 1) & 0x80)) ||
((*p & 0x80) && g_ascii_isalpha (*(p + 1)))) {
mark++;
total++;
}
/* Current and next symbols are of one class */
else if (((*p & 0x80) &&
(*(p + 1) & 0x80)) ||
(g_ascii_isalpha (*p) && g_ascii_isalpha (*(p + 1)))) {
total++;
}
p++;
remain--;
}
}
else {
memset (&scripts, 0, sizeof (scripts));
while (remain > 0) {
c = g_utf8_get_char_validated (p, remain);
if (c == (gunichar) - 2 || c == (gunichar) - 1) {
/* Invalid characters detected, stop processing */
return FALSE;
}
scc = g_unichar_get_script (c);
if (scc < (gint)G_N_ELEMENTS (scripts)) {
scripts[scc]++;
}
p1 = g_utf8_next_char (p);
remain -= p1 - p;
p = p1;
if (remain > 0) {
t = g_utf8_get_char_validated (p, remain);
if (t == (gunichar) - 2 || t == (gunichar) - 1) {
/* Invalid characters detected, stop processing */
return FALSE;
}
sct = g_unichar_get_script (t);
if (g_unichar_isalpha (c) && g_unichar_isalpha (t)) {
/* We have two unicode alphanumeric characters, so we can check its script */
if (sct != scc) {
mark++;
}
total++;
}
p1 = g_utf8_next_char (p);
remain -= p1 - p;
p = p1;
}
}
/* Detect the mostly charset of this part */
for (i = 0; i < G_N_ELEMENTS (scripts); i++) {
if (scripts[i] > max) {
max = scripts[i];
sel = i;
}
}
part->script = sel;
}
if (total == 0) {
return 0;
}
return ((double)mark / (double)total) > chartable_module_ctx->threshold;
}
static void
chartable_symbol_callback (struct rspamd_task *task, void *unused)
{
guint i;
struct mime_text_part *part;
for (i = 0; i < task->text_parts->len; i ++) {
part = g_ptr_array_index (task->text_parts, i);
if (!IS_PART_EMPTY (part) && check_part (part, task->cfg->raw_mode)) {
rspamd_task_insert_result (task, chartable_module_ctx->symbol, 1, NULL);
}
}
}
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