[Feature] Add dedicated ZW spaces detection for URLs

Issue: #2725

rules/misc.lua

@@ -101,25 +101,41 @@ rspamd_config.DATE_IN_PAST = {
   type = 'mime',
 }
 
-rspamd_config.R_SUSPICIOUS_URL = {
+local obscured_id = rspamd_config:register_symbol{
   callback = function(task)
     local urls = task:get_urls()
 
     if urls then
       for _,u in ipairs(urls) do
-        if u:is_obscured() then
+        local fl = u:get_flags()
+        if fl.obscured then
           task:insert_result('R_SUSPICIOUS_URL', 1.0, u:get_host())
         end
+        if fl.zw_spaces then
+          task:insert_result('ZERO_WIDTH_SPACE_URL', 1.0, u:get_host())
+        end
       end
     end
+
     return false
   end,
+  name = 'R_SUSPICIOUS_URL',
   score = 5.0,
   one_shot = true,
   description = 'Obfusicated or suspicious URL has been found in a message',
   group = 'url'
 }
 
+rspamd_config:register_symbol{
+  type = 'virtual',
+  name = 'ZERO_WIDTH_SPACE_URL',
+  score = 7.0,
+  one_shot = true,
+  description = 'Zero width space in url',
+  group = 'url',
+  parent = obscured_id,
+}
+
 
 rspamd_config.ENVFROM_PRVS = {
   callback = function (task)

src/libserver/html.c

@@ -1351,6 +1351,10 @@ rspamd_html_process_url (rspamd_mempool_t *pool, const gchar *start, guint len,
 
 	if (norm_res & (RSPAMD_UNICODE_NORM_ZERO_SPACES|RSPAMD_UNICODE_NORM_ERROR)) {
 		saved_flags |= RSPAMD_URL_FLAG_OBSCURED;
+
+		if (norm_res & RSPAMD_UNICODE_NORM_ZERO_SPACES) {
+			saved_flags |= RSPAMD_URL_FLAG_ZW_SPACES;
+		}
 	}
 
 	rc = rspamd_url_parse (url, decoded, dlen, pool, RSPAMD_URL_PARSE_HREF);

src/libserver/url.h

@@ -27,6 +27,7 @@ enum rspamd_url_flags {
 	RSPAMD_URL_FLAG_HAS_USER = 1 << 14,
 	RSPAMD_URL_FLAG_SCHEMALESS = 1 << 15,
 	RSPAMD_URL_FLAG_UNNORMALISED = 1 << 16,
+	RSPAMD_URL_FLAG_ZW_SPACES = 1 << 17,
 };
 
 struct rspamd_url_tag {

src/lua/lua_url.c

@@ -875,6 +875,7 @@ lua_url_all (lua_State *L)
  * - `has_user`: URL has user part
  * - `schemaless`: URL has no schema
  * - `unnormalised`: URL has some unicode unnormalities
+ * - `zw_spaces`: URL has some zero width spaces
  * @return {table} URL flags
  */
 #define PUSH_FLAG(fl, name) do { \
@@ -914,6 +915,7 @@ lua_url_get_flags (lua_State *L)
 		PUSH_FLAG (RSPAMD_URL_FLAG_HAS_USER, "has_user");
 		PUSH_FLAG (RSPAMD_URL_FLAG_SCHEMALESS, "schemaless");
 		PUSH_FLAG (RSPAMD_URL_FLAG_UNNORMALISED, "unnormalised");
+		PUSH_FLAG (RSPAMD_URL_FLAG_ZW_SPACES, "zw_spaces");
 	}
 	else {
 		return luaL_error (L, "invalid arguments");