[Project] Initial addition of lua helpers for fuzzy

lualib/lua_fuzzy.lua

@@ -0,0 +1,103 @@
+--[[
+Copyright (c) 2018, Vsevolod Stakhov <vsevolod@highsecure.ru>
+
+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 lua_fuzzy
+-- This module contains helper functions for supporting fuzzy check module
+--]]
+
+
+local N = "lua_fuzzy"
+local lua_util = require "lua_util"
+local rspamd_logger = require "rspamd_logger"
+local ts = require("tableshape").types
+
+-- Filled by C code, indexed by number in this table
+local rules = {}
+
+-- Pre-defined rules options
+local policies = {
+  recommended = {
+    min_bytes = 1024,
+    min_height = 500,
+    min_width = 500,
+    min_length = 100, -- short words multiplier
+    text_multiplier = 4.0, -- divide min_bytes by 4 for texts
+    mime_types = {"*"},
+    short_text_direct_hash = true,
+  }
+}
+
+local default_policy = policies.recommended
+
+local policy_schema = ts.shape{
+  min_bytes = ts.number + ts.string / tonumber,
+  min_height = ts.number + ts.string / tonumber,
+  min_width = ts.number + ts.string / tonumber,
+  min_length = ts.number + ts.string / tonumber,
+  text_multiplier = ts.number,
+  mime_types = ts.array_of(ts.string),
+  short_text_direct_hash = ts.bool,
+}
+
+
+local exports = {}
+
+
+--[[[
+-- @function lua_fuzzy.register_policy(name, policy)
+-- Adds a new policy with name `name`. Must be valid, checked using policy_schema
+--]]
+exports.register_policy = function(name, policy)
+  if policies[name] then
+    rspamd_logger.warnx(rspamd_config, "overriding policy %s", name)
+  end
+
+  local parsed_policy,err = policy_schema:transform(policy)
+
+  if not parsed_policy then
+    rspamd_logger.errx(rspamd_config, 'invalid fuzzy rule policy %s: %s',
+        name, err)
+
+    return
+  else
+    policies.name = parsed_policy
+  end
+end
+
+--[[[
+-- @function lua_fuzzy.process_rule(rule)
+-- Processes fuzzy rule (applying policies or defaults if needed). Returns policy id
+--]]
+exports.process_rule = function(rule)
+  local processed_rule = lua_util.shallowcopy(rule)
+  local policy = default_policy
+
+  if processed_rule.policy then
+    policy = policies[processed_rule.policy]
+
+    if policy then
+      processed_rule = lua_util.override_defaults(policy, processed_rule)
+    else
+      rspamd_logger.warnx(rspamd_config, "unknown policy %s", processed_rule.policy)
+    end
+  end
+
+  table.insert(rules, processed_rule)
+  return #rules
+end
+
+return exports