path: root/src/plugins/lua/settings.lua

--[[
Copyright (c) 2011-2015, 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.
]]--

if confighelp then
  return
end

-- This plugin implements user dynamic settings
-- Settings documentation can be found here:
-- https://rspamd.com/doc/configuration/settings.html

local rspamd_logger = require "rspamd_logger"
local rspamd_maps = require "lua_maps"
local lua_util = require "lua_util"
local rspamd_ip = require "rspamd_ip"
local rspamd_regexp = require "rspamd_regexp"
local lua_selectors = require "lua_selectors"
local lua_settings = require "lua_settings"
local ucl = require "ucl"
local fun = require "fun"
local rspamd_mempool = require "rspamd_mempool"

local redis_params

local settings = {}
local N = "settings"
local settings_initialized = false
local max_pri = 0
local module_sym_id -- Main module symbol

local function apply_settings(task, to_apply, id)
  task:set_settings(to_apply)
  task:cache_set('settings', to_apply)

  if id then
    task:set_settings_id(id)
  end

  if to_apply['add_headers'] or to_apply['remove_headers'] then
    local rep = {
      add_headers = to_apply['add_headers'] or {},
      remove_headers = to_apply['remove_headers'] or {},
    }
    task:set_rmilter_reply(rep)
  end

  if to_apply.flags and type(to_apply.flags) == 'table' then
    for _,fl in ipairs(to_apply.flags) do
      task:set_flag(fl)
    end
  end

  if to_apply.symbols then
    -- Add symbols, specified in the settings
    if #to_apply.symbols > 0 then
      -- Array like symbols
      for _,val in ipairs(to_apply.symbols) do
        task:insert_result(val, 1.0)
      end
    else
      -- Object like symbols
      for k,v in pairs(to_apply.symbols) do
        if type(v) == 'table' then
          task:insert_result(k, v.score or 1.0, v.options or {})
        elseif tonumber(v) then
          task:insert_result(k, tonumber(v))
        end
      end
    end
  end

  if to_apply.subject then
    task:set_metric_subject(to_apply.subject)
  end

  -- E.g.
  -- messages = { smtp_message = "5.3.1 Go away" }
  if to_apply.messages and type(to_apply.messages) == 'table' then
    fun.each(function(category, message)
      task:append_message(message, category)
    end, to_apply.messages)
  end
end

-- Checks for overridden settings within query params and returns 3 values:
-- * Apply element
-- * Settings ID element if found
-- * Priority of the settings according to the place where it is found
--
-- If no override has been found, it returns `false`
local function check_query_settings(task)
  -- Try 'settings' attribute
  local settings_id = task:get_settings_id()
  local query_set = task:get_request_header('settings')
  if query_set then

    local parser = ucl.parser()
    local res,err = parser:parse_string(tostring(query_set))
    if res then
      if settings_id then
        rspamd_logger.warnx(task, "both settings-id '%s' and settings headers are presented, ignore settings-id; ",
            tostring(settings_id))
      end
      local settings_obj = parser:get_object()

      -- Treat as low priority
      return settings_obj,nil,1
    else
      rspamd_logger.errx(task, 'Parse error: %s', err)
    end
  end

  local query_maxscore = task:get_request_header('maxscore')
  local nset

  if query_maxscore then
    if settings_id then
      rspamd_logger.infox(task, "both settings id '%s' and maxscore '%s' headers are presented, merge them; " ..
        "settings id has priority",
        tostring(settings_id), tostring(query_maxscore))
    end
    -- We have score limits redefined by request
    local ms = tonumber(tostring(query_maxscore))
    if ms then
      nset = {
        actions = {
          reject = ms
        }
      }

      local query_softscore = task:get_request_header('softscore')
      if query_softscore then
        local ss = tonumber(tostring(query_softscore))
        nset.actions['add header'] = ss
      end

      if not settings_id then
        rspamd_logger.infox(task, 'apply maxscore = %s', nset.actions)
        -- Maxscore is low priority
        return nset, nil, 1
      end
    end
  end

  if settings_id and settings_initialized then
    local cached = lua_settings.settings_by_id(settings_id)

    if cached then
      local elt = cached.settings
      if elt['whitelist'] then
        elt['apply'] = {whitelist = true}
      end

      if elt.apply then
        if nset then
          elt.apply = lua_util.override_defaults(nset, elt.apply)
        end
        return elt.apply, cached, cached.priority or 1
      end
    else
      rspamd_logger.warnx(task, 'no settings id "%s" has been found', settings_id)
      if nset then
        rspamd_logger.infox(task, 'apply maxscore = %s', nset.actions)
        return nset, nil, 1
      end
    end
  else
    if nset then
      rspamd_logger.infox(task, 'apply maxscore = %s', nset.actions)
      return nset, nil, 1
    end
  end

  return false
end

local function check_addr_setting(expected, addr)
  local function check_specific_addr(elt)
    if expected.name then
      if rspamd_maps.rspamd_maybe_check_map(expected.name, elt.addr) then
        return true
      end
    end
    if expected.user then
      if rspamd_maps.rspamd_maybe_check_map(expected.user, elt.user) then
        return true
      end
    end
    if expected.domain and elt.domain then
      if rspamd_maps.rspamd_maybe_check_map(expected.domain, elt.domain) then
        return true
      end
    end
    if expected.regexp then
      if expected.regexp:match(elt.addr) then
        return true
      end
    end
    return false
  end

  for _, e in ipairs(addr) do
    if check_specific_addr(e) then
      return true
    end
  end

  return false
end

local function check_string_setting(expected, str)
  if expected.regexp then
    if expected.regexp:match(str) then
      return true
    end
  elseif expected.check then
    if rspamd_maps.rspamd_maybe_check_map(expected.check, str) then
      return true
    end
  end
  return false
end

local function check_ip_setting(expected, ip)
  if not expected[2] then
    if rspamd_maps.rspamd_maybe_check_map(expected[1], ip:to_string()) then
      return true
    end
  else
    if expected[2] ~= 0 then
      local nip = ip:apply_mask(expected[2])
      if nip and nip:to_string() == expected[1]:to_string() then
        return true
      end
    elseif ip:to_string() == expected[1]:to_string() then
      return true
    end
  end

  return false
end

local function priority_to_string(pri)
  if pri then
    if pri >= 3 then
      return "high"
    elseif pri >= 2 then
      return "medium"
    end
  end

  return "low"
end

-- Check limit for a task
local function check_settings(task)
  local function check_specific_setting(rule, matched)
    local res = false

    local function process_atom(atom)
      local elt = rule.checks[atom]

      if elt then
        local input = elt.extract(task)
        if not input then return false end

        if elt.check(input) then
          matched[#matched + 1] = atom
          return 1.0
        end
      else
        rspamd_logger.errx(task, 'error in settings: check %s is not defined!', atom)
      end

      return 0
    end

    res = rule.expression and rule.expression:process(process_atom)

    if res and res > 0 then
      if rule['whitelist'] then
        rule['apply'] = {whitelist = true}
      end

      return rule
    end

    return nil
  end

  -- Check if we have override as query argument
  local query_apply,id_elt,priority = check_query_settings(task)

  local function maybe_apply_query_settings()
    if query_apply then
      if id_elt then
        apply_settings(task, query_apply, id_elt.id)
        rspamd_logger.infox(task, "applied settings id %s(%s); priority %s",
            id_elt.name, id_elt.id, priority_to_string(priority))
      else
        apply_settings(task, query_apply, nil)
        rspamd_logger.infox(task, "applied settings from query; priority %s",
            priority_to_string(priority))
      end
    end
  end

  local min_pri = 1
  if query_apply then
    if priority >= min_pri then
      -- Do not check lower or equal priorities
      min_pri = priority + 1
    end

    if priority > max_pri then
      -- Our internal priorities are lower then a priority from query, so no need to check
      maybe_apply_query_settings()

      return
    end
  end

  -- Do not waste resources
  if not settings_initialized then
    maybe_apply_query_settings()
    return
  end

  -- Match rules according their order
  local applied = false

  for pri = max_pri,min_pri,-1 do
    if not applied and settings[pri] then
      for _,s in ipairs(settings[pri]) do
        local matched = {}

        lua_util.debugm(N, task, "check for settings element %s",
            s.name)
        local result = check_specific_setting(s.rule, matched)
        -- Can use xor here but more complicated for reading
        if result then
          if s.rule['apply'] then
            if s.rule.id then
              -- Extract static settings
              local cached = lua_settings.settings_by_id(s.rule.id)

              if not cached or not cached.settings or not cached.settings.apply then
                rspamd_logger.errx(task, 'unregistered settings id found: %s!', s.rule.id)
              else
                rspamd_logger.infox(task, "<%s> apply static settings %s (id = %s); %s matched; priority %s",
                    task:get_message_id(),
                    cached.name, s.rule.id,
                    table.concat(matched, ','),
                    priority_to_string(pri))
                apply_settings(task, cached.settings.apply, s.rule.id)
              end

            else
              -- Dynamic settings
              rspamd_logger.infox(task, "<%s> apply settings according to rule %s (%s matched)",
                  task:get_message_id(), s.name, table.concat(matched, ','))
              apply_settings(task, s.rule.apply, nil)
            end

            applied = true
          end
          if s.rule['symbols'] then
            -- Add symbols, specified in the settings
            fun.each(function(val)
              task:insert_result(val, 1.0)
            end, s.rule['symbols'])
          end
        end
      end
    end
  end

  if not applied then
    maybe_apply_query_settings()
  end

end

-- Process settings based on their priority
local function process_settings_table(tbl, allow_ids, mempool)
  local get_priority = function(elt)
    local pri_tonum = function(p)
      if p then
        if type(p) == "number" then
          return tonumber(p)
        elseif type(p) == "string" then
          if p == "high" then
            return 3
          elseif p == "medium" then
            return 2
          end

        end

      end

      return 1
    end

    return pri_tonum(elt['priority'])
  end

  -- Check the setting element internal data
  local process_setting_elt = function(name, elt)

    lua_util.debugm(N, rspamd_config, 'process settings "%s"', name)
    -- Process IP address: converted to a table {ip, mask}
    local function process_ip_condition(ip)
      local out = {}

      if type(ip) == "table" then
        for _,v in ipairs(ip) do
          table.insert(out, process_ip_condition(v))
        end
      elseif type(ip) == "string" then
        local slash = string.find(ip, '/')

        if not slash then
          -- Just a plain IP address
          local res = rspamd_ip.from_string(ip)

          if res:is_valid() then
            out[1] = res
            out[2] = 0
          else
            -- It can still be a map
            out[1] = res
          end
        else
          local res = rspamd_ip.from_string(string.sub(ip, 1, slash - 1))
          local mask = tonumber(string.sub(ip, slash + 1))

          if res:is_valid() then
            out[1] = res
            out[2] = mask
          else
            rspamd_logger.errx(rspamd_config, "bad IP address: " .. ip)
            return nil
          end
        end
      else
        return nil
      end

      return out
    end

    -- Process email like condition, converted to a table with fields:
    -- name - full email (surprise!)
    -- user - user part
    -- domain - domain part
    -- regexp - full email regexp (yes, it sucks)
    local function process_email_condition(addr)
      local out = {}
      if type(addr) == "table" then
        for _,v in ipairs(addr) do
          table.insert(out, process_email_condition(v))
        end
      elseif type(addr) == "string" then
        if string.sub(addr, 1, 4) == "map:" then
          -- It is map, don't apply any extra logic
          out['name'] = addr
        else
          local start = string.sub(addr, 1, 1)
          if start == '/' then
            -- It is a regexp
            local re = rspamd_regexp.create(addr)
            if re then
              out['regexp'] = re
            else
              rspamd_logger.errx(rspamd_config, "bad regexp: " .. addr)
              return nil
            end

          elseif start == '@' then
            -- It is a domain if form @domain
            out['domain'] = string.sub(addr, 2)
          else
            -- Check user@domain parts
            local at = string.find(addr, '@')
            if at then
              -- It is full address
              out['name'] = addr
            else
              -- It is a user
              out['user'] = addr
            end
          end
        end
      else
        return nil
      end

      return out
    end

    -- Convert a plain string condition to a table:
    -- check - string to match
    -- regexp - regexp to match
    local function process_string_condition(addr)
      local out = {}
      if type(addr) == "table" then
        for _,v in ipairs(addr) do
          table.insert(out, process_string_condition(v))
        end
      elseif type(addr) == "string" then
        if string.sub(addr, 1, 4) == "map:" then
          -- It is map, don't apply any extra logic
          out['check'] = addr
        else
          local start = string.sub(addr, 1, 1)
          if start == '/' then
            -- It is a regexp
            local re = rspamd_regexp.create(addr)
            if re then
              out['regexp'] = re
            else
              rspamd_logger.errx(rspamd_config, "bad regexp: " .. addr)
              return nil
            end

          else
            out['check'] = addr
          end
        end
      else
        return nil
      end

      return out
    end

    local convert_to_table = function(chk_elt, out)
      if type(chk_elt) == 'string' then
        return {out}
      end

      return out
    end

    -- Used to create a checking closure: if value matches expected somehow, return true
    local function gen_check_closure(expected, check_func)
      return function(value)
        if not value then return false end

        if type(value) == 'function' then
          value = value()
        end

        if value then

          if not check_func then
            check_func = function(a, b) return a == b end
          end

          local ret = fun.any(function(d)
            return check_func(d, value)
          end, expected)
          if ret then
            return true
          end
        end

        return false
      end
    end

    local out = {}

    local checks = {}
    if elt['ip'] then
      local ips_table = process_ip_condition(elt['ip'])

      if ips_table then
        lua_util.debugm(N, rspamd_config, 'added ip condition to "%s": %s',
            name, ips_table)
        checks.ip = {
          check = gen_check_closure(convert_to_table(elt.ip, ips_table), check_ip_setting),
          extract = function(task)
            local ip = task:get_from_ip()
            if ip and ip:is_valid() then return ip end
            return nil
          end,
        }
      end
    end
    if elt['client_ip'] then
      local client_ips_table = process_ip_condition(elt['client_ip'])

      if client_ips_table then
        lua_util.debugm(N, rspamd_config, 'added client_ip condition to "%s": %s',
            name, client_ips_table)
        checks.client_ip = {
          check = gen_check_closure(convert_to_table(elt.client_ip, client_ips_table),
              check_ip_setting),
          extract = function(task)
            local ip = task:get_client_ip()
            if ip:is_valid() then return ip end
            return nil
          end,
        }
      end
    end
    if elt['from'] then
      local from_condition = process_email_condition(elt['from'])

      if from_condition then
        lua_util.debugm(N, rspamd_config, 'added from condition to "%s": %s',
            name, from_condition)
        checks.from = {
          check = gen_check_closure(convert_to_table(elt.from, from_condition),
              check_addr_setting),
          extract = function(task)
            return task:get_from(1)
          end,
        }
      end
    end
    if elt['rcpt'] then
      local rcpt_condition = process_email_condition(elt['rcpt'])
      if rcpt_condition then
        lua_util.debugm(N, rspamd_config, 'added rcpt condition to "%s": %s',
            name, rcpt_condition)
        checks.rcpt = {
          check = gen_check_closure(convert_to_table(elt.rcpt, rcpt_condition),
              check_addr_setting),
          extract = function(task)
            return task:get_recipients(1)
          end,
        }
      end
    end
    if elt['from_mime'] then
      local from_mime_condition = process_email_condition(elt['from_mime'])

      if from_mime_condition then
        lua_util.debugm(N, rspamd_config, 'added from_mime condition to "%s": %s',
            name, from_mime_condition)
        checks.from_mime = {
          check = gen_check_closure(convert_to_table(elt.from_mime, from_mime_condition),
              check_addr_setting),
          extract = function(task)
            return task:get_from(2)
          end,
        }
      end
    end
    if elt['rcpt_mime'] then
      local rcpt_mime_condition = process_email_condition(elt['rcpt'])
      if rcpt_mime_condition then
        lua_util.debugm(N, rspamd_config, 'added rcpt mime condition to "%s": %s',
            name, rcpt_mime_condition)
        checks.rcpt_mime = {
          check = gen_check_closure(convert_to_table(elt.rcpt_mime, rcpt_mime_condition),
              check_addr_setting),
          extract = function(task)
            return task:get_recipients(2)
          end,
        }
      end
    end
    if elt['user'] then
      local user_condition = process_email_condition(elt['user'])
      if user_condition then
        lua_util.debugm(N, rspamd_config, 'added user condition to "%s": %s',
            name, user_condition)
        checks.user = {
          check = gen_check_closure(convert_to_table(elt.user, user_condition),
              check_addr_setting),
          extract = function(task)
            local uname = task:get_user()
            local user = {}
            if uname then
              user[1] = {}
              local localpart, domainpart = string.gmatch(uname, "(.+)@(.+)")()
              if localpart then
                user[1]["user"] = localpart
                user[1]["domain"] = domainpart
                user[1]["addr"] = uname
              else
                user[1]["user"] = uname
                user[1]["addr"] = uname
              end

              return user
            end

            return nil
          end,
        }
      end
    end
    if elt['hostname'] then
      local hostname_condition = process_string_condition(elt['hostname'])
      if hostname_condition then
        lua_util.debugm(N, rspamd_config, 'added hostname condition to "%s": %s',
            name, hostname_condition)
        checks.hostname = {
          check = gen_check_closure(convert_to_table(elt.hostname, hostname_condition),
              check_string_setting),
          extract = function(task)
            return task:get_hostname() or ''
          end,
        }
      end
    end
    if elt['authenticated'] then
      lua_util.debugm(N, rspamd_config, 'added authenticated condition to "%s"',
          name)
      checks.authenticated = {
        check = function(value) if value then return true end return false end,
        extract = function(task)
          return task:get_user()
        end
      }
    end
    if elt['local'] then
      lua_util.debugm(N, rspamd_config, 'added local condition to "%s"',
          name)
      checks['local'] = {
        check = function(value) if value then return true end return false end,
        extract = function(task)
          local ip = task:get_from_ip()
          if not ip or not ip:is_valid() then
            return nil
          end

          if ip:is_local() then
            return true
          else
            return nil
          end
        end
      }
    end

    local aliases = {}
    -- This function is used to convert compound condition with
    -- generic type and specific part (e.g. `header`, `Content-Transfer-Encoding`)
    -- to a set of usable check elements:
    -- `generic:specific` - most common part
    -- `generic:<order>` - e.g. `header:1` for the first header
    -- `generic:safe` - replace unsafe stuff with safe + lowercase
    -- also aliases entry is set to avoid implicit expression
    local function process_compound_condition(cond, generic, specific)
      local full_key = generic .. ':' .. specific
      checks[full_key] = cond

      -- Try numeric key
      for i=1,1000 do
        local num_key = generic .. ':' .. tostring(i)
        if not checks[num_key]  then
          checks[num_key] = cond
          aliases[num_key] = true
          break
        end
      end

      local safe_key = generic .. ':' ..
          specific:gsub('[:%-+&|><]', '_')
                  :gsub('%(', '[')
                  :gsub('%)', ']')
                  :lower()

      if not checks[safe_key] then
        checks[safe_key] = cond
        aliases[safe_key] = true
      end

      return safe_key
  end
    -- Headers are tricky:
    -- We create an closure with extraction function depending on header name
    -- We also inserts it into `checks` table as an atom in form header:<hname>
    -- Check function depends on the input:
    -- * for something that looks like `header = "/bar/"` we create a regexp
    -- * for something that looks like `header = true` we just check the existence
    local function process_header_elt(table_element, extractor_func)
      if elt[table_element] then
        for k, v in pairs(elt[table_element]) do
          if type(v) == 'string' then
            local re = rspamd_regexp.create(v)
            if re then
              local cond = {
                check = function(values)
                  return fun.any(function(c) return re:match(c) end, values)
                end,
                extract = extractor_func(k),
              }
              local skey = process_compound_condition(cond, table_element,
                  k)
              lua_util.debugm(N, rspamd_config, 'added %s condition to "%s": %s =~ %s',
                  skey, name, k, v)
            end
          elseif type(v) == 'boolean' then
            local cond = {
              check = function(values)
                if #values == 0 then return (not v) end
                return v
              end,
              extract = extractor_func(k),
            }

            local skey = process_compound_condition(cond, table_element,
                k)
            lua_util.debugm(N, rspamd_config, 'added %s condition to "%s": %s == %s',
                skey, name, k, v)
          else
            rspamd_logger.errx(rspamd_config, 'invalid %s %s = %s', table_element, k, v)
          end
        end
      end
    end

    process_header_elt('request_header', function(hname)
      return function(task)
        local rh = task:get_request_header(hname)
        if rh then return {rh} end
        return {}
      end
    end)
    process_header_elt('header', function(hname)
      return function(task)
        local rh = task:get_header_full(hname)
        if rh then
          return fun.totable(fun.map(function(h) return h.decoded end, rh))
        end
        return {}
      end
    end)

    if elt['selector'] then
      local sel = lua_selectors.create_selector_closure(rspamd_config, elt.selector,
          elt.delimiter or "")

      if sel then
        local cond = {
          check = function(values)
            return fun.any(function(c)
              return c
            end, values)
          end,
          extract = sel,
        }
        local skey = process_compound_condition(cond, 'selector', elt.selector)
        lua_util.debugm(N, rspamd_config, 'added selector condition to "%s": %s',
            name, skey)
      end

    end

    -- Special, special case!
    local inverse = false
    if elt['inverse'] then
      lua_util.debugm(N, rspamd_config, 'added inverse condition to "%s"',
          name)
      inverse = true
    end

    -- Killmeplease
    local nchecks = 0
    for _,_ in pairs(checks) do nchecks = nchecks + 1 end

    if nchecks > 0 then
      -- Now we can deal with the expression!
      if not elt.expression then
        -- Artificial & expression to deal with the legacy parts
        -- Here we get all keys and concatenate them with '&&'
        local s = ' && '
        -- By De Morgan laws
        if inverse then s = ' || ' end
        -- Exclude aliases and join all checks by key
        local expr_str = table.concat(lua_util.keys(fun.filter(
            function(k, _) return not aliases[k] end,
            checks)), s)

        if inverse then
          expr_str = string.format('!(%s)', expr_str)
        end

        elt.expression = expr_str
        lua_util.debugm(N, rspamd_config, 'added implicit settings expression for %s: %s',
            name, expr_str)
      end

      -- Parse expression's sanity
      local function parse_atom(str)
        local atom = table.concat(fun.totable(fun.take_while(function(c)
          if string.find(', \t()><+!|&\n', c) then
            return false
          end
          return true
        end, fun.iter(str))), '')

        if checks[atom] then
          return atom
        end

        rspamd_logger.errx(rspamd_config,
            'use of undefined element "%s" when parsing settings expression, known checks: %s',
            atom, table.concat(fun.totable(fun.map(function(k, _) return k end, checks)), ','))

        return nil
      end

      local rspamd_expression = require "rspamd_expression"
      out.expression = rspamd_expression.create(elt.expression, parse_atom,
          mempool)
      out.checks = checks

      if not out.expression then
        rspamd_logger.errx(rspamd_config, 'cannot parse expression %s for %s',
            elt.expression, name)
      else
        lua_util.debugm(N, rspamd_config, 'registered settings %s with %s checks',
            name, nchecks)
      end
    else
      lua_util.debugm(N, rspamd_config, 'registered settings %s with no checks',
          name)
    end

    -- Process symbols part/apply part
    if elt['symbols'] then
      lua_util.debugm(N, rspamd_config, 'added symbols condition to "%s": %s',
          name, elt.symbols)
      out['symbols'] = elt['symbols']
    end


    if elt['apply'] then
      -- Just insert all metric results to the action key
      out['apply'] = elt['apply']
    elseif elt['whitelist'] or elt['want_spam'] then
      out['whitelist'] = true
    else
      rspamd_logger.errx(rspamd_config, "no actions in settings: " .. name)
      return nil
    end

    if allow_ids then
      if not elt.id then
        elt.id = name
      end

      if elt['id'] then
        out.id = lua_settings.register_settings_id(elt.id, out)
        lua_util.debugm(N, rspamd_config,
            'added settings id to "%s": %s -> %s',
            name, elt.id, out.id)
      end

      if elt.apply and elt.apply.symbols then
        -- Register virtual symbols
        for k,v in pairs(elt.apply.symbols) do
          local rtb = {
            type = 'virtual',
            parent = module_sym_id,
          }
          if type(k) == 'number' and type(v) == 'string' then
            rtb.name = v
          elseif type(k) == 'string' then
            rtb.name = k
          end
          if out.id then
            rtb.allowed_ids = tostring(elt.id)
          end
          rspamd_config:register_symbol(rtb)
        end
      end
    else
      if elt['id'] then
        rspamd_logger.errx(rspamd_config,
            'cannot set static IDs from dynamic settings, please read the docs')
      end
    end

    return out
  end

  settings_initialized = false
  -- filter trash in the input
  local ft = fun.filter(
    function(_, elt)
      if type(elt) == "table" then
        return true
      end
      return false
    end, tbl)

  -- clear all settings
  max_pri = 0
  local nrules = 0
  for k in pairs(settings) do settings[k]={} end
  -- fill new settings by priority
  fun.for_each(function(k, v)
    local pri = get_priority(v)
    if pri > max_pri then max_pri = pri end
    if not settings[pri] then
      settings[pri] = {}
    end
    local s = process_setting_elt(k, v)
    if s then
      table.insert(settings[pri], {name = k, rule = s})
      nrules = nrules + 1
    end
  end, ft)
  -- sort settings with equal priopities in alphabetical order
  for pri,_ in pairs(settings) do
    table.sort(settings[pri], function(a,b) return a.name < b.name end)
  end

  settings_initialized = true
  rspamd_logger.infox(rspamd_config, 'loaded %1 elements of settings', nrules)

  return true
end

-- Parse settings map from the ucl line
local settings_map_pool
local function process_settings_map(map_text)
  local parser = ucl.parser()
  local res,err = parser:parse_string(map_text)
  if not res then
    rspamd_logger.warnx(rspamd_config, 'cannot parse settings map: ' .. err)
  else
    if settings_map_pool then
      settings_map_pool:destroy()
    end

    settings_map_pool = rspamd_mempool.create()

    local obj = parser:get_object()
    if obj['settings'] then
      process_settings_table(obj['settings'], false, settings_map_pool)
    else
      process_settings_table(obj, false, settings_map_pool)
    end
  end

  return res
end

local function gen_redis_callback(handler, id)
  return function(task)
    local key = handler(task)

    local function redis_settings_cb(err, data)
      if not err and type(data) == 'table' then
        for _, d in ipairs(data) do
          if type(d) == 'string' then
            local parser = ucl.parser()
            local res,ucl_err = parser:parse_string(d)
            if not res then
              rspamd_logger.warnx(rspamd_config, 'cannot parse settings from redis: %s',
                ucl_err)
            else
              local obj = parser:get_object()
              rspamd_logger.infox(task, "<%1> apply settings according to redis rule %2",
                task:get_message_id(), id)
              apply_settings(task, obj, nil)
              break
            end
          end
        end
      elseif err then
        rspamd_logger.errx(task, 'Redis error: %1', err)
      end
    end

    if not key then
      lua_util.debugm(N, task, 'handler number %s returned nil', id)
      return
    end

    local keys
    if type(key) == 'table' then
      keys = key
    else
      keys = {key}
    end
    key = keys[1]

    local ret,_,_ = rspamd_redis_make_request(task,
      redis_params, -- connect params
      key, -- hash key
      false, -- is write
      redis_settings_cb, --callback
      'MGET', -- command
      keys -- arguments
    )
    if not ret then
      rspamd_logger.errx(task, 'Redis MGET failed: %s', ret)
    end
  end
end

local redis_section = rspamd_config:get_all_opt("settings_redis")
local redis_key_handlers = {}

if redis_section then
  redis_params = rspamd_parse_redis_server('settings_redis')
  if redis_params then
    local handlers = redis_section.handlers

    for id,h in pairs(handlers) do
      local chunk,err = load(h)

      if not chunk then
        rspamd_logger.errx(rspamd_config, 'Cannot load handler from string: %s',
            tostring(err))
      else
        local res,func = pcall(chunk)
        if not res then
          rspamd_logger.errx(rspamd_config, 'Cannot add handler from string: %s',
            tostring(func))
        else
          redis_key_handlers[id] = func
        end
      end
    end
  end

  fun.each(function(id, h)
    rspamd_config:register_symbol({
      name = 'REDIS_SETTINGS' .. tostring(id),
      type = 'prefilter,nostat',
      callback = gen_redis_callback(h, id),
      priority = 10,
      flags = 'empty',
    })
  end, redis_key_handlers)
end

module_sym_id = rspamd_config:register_symbol({
  name = 'SETTINGS_CHECK',
  type = 'prefilter',
  callback = check_settings,
  priority = 10,
  flags = 'empty,nostat,explicit_disable,ignore_passthrough',
})

local set_section = rspamd_config:get_all_opt("settings")

if set_section and set_section[1] and type(set_section[1]) == "string" then
  -- Just a map of ucl
  local map_attrs = {
    url = set_section[1],
    description = "settings map",
    callback = process_settings_map,
    opaque_data = true
  }
  if not rspamd_config:add_map(map_attrs) then
    rspamd_logger.errx(rspamd_config, 'cannot load settings from %1', set_section)
  end
elseif set_section and type(set_section) == "table" then
  settings_map_pool = rspamd_mempool.create()
  process_settings_table(set_section, true, settings_map_pool)
end

rspamd_config:add_config_unload(function()
  if settings_map_pool then
    settings_map_pool:destroy()
  end
end)