rspamd.local.lua

rspamd_config.NO_MX_FOR_RETURN_ADDR = {
  callback = function(task)
    local return_addr
    local hdr_from = task:get_header('From')
    local hdr_replyto = task:get_header('Reply-To')

    -- Work out the return address
    if (hdr_replyto) then
      return_addr = hdr_replyto
    elseif (hdr_from) then
      return_addr = hdr_from
    else
      return false
    end
    
    local logger = require "rspamd_logger"

    -- Parse return address
    local util = require "rspamd_util"
    local parsed_return_addr = util.parse_mail_address(return_addr)
    if not (parsed_return_addr and parsed_return_addr[1]) then
      logger.infox("Unable to parse return address: %1", return_addr)
      return false
    end

    local return_domain = parsed_return_addr[1]['domain']

    local function dns_a_cb(resolver, to_resolve, results, err)
      if not results then
        if (err == 'requested record is not found') then
          -- TODO: check for AAAA record (rspamd has no resolve_aaa function)
          task:insert_result('NO_MX_FOR_RETURN_ADDR', 1.0, return_domain)
        end
        -- TODO: check IP address returned is valid
      end
    end

    local function dns_mx_cb(resolver, to_resolve, results, err)
      if not results then
        if (err == 'requested record is not found') then
          -- Check A record
          task:get_resolver():resolve_a(task:get_session(), task:get_mempool(), 
                                        return_domain, dns_a_cb)
          return
        end
        -- TODO: resolve MX records to IP addresses
        --       and check that at least one is valid.
      end
    end

    task:get_resolver():resolve_mx(task:get_session(), task:get_mempool(), 
                                   return_domain, dns_mx_cb)
  end,
  score = 3.0,
  description = 'Return address domain has no valid MX'
}