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path: root/src/plugins/lua/emails.lua
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--[[
Copyright (c) 2011-2015, Vsevolod Stakhov <vsevolod@highsecure.ru>
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
]]--

-- Emails is module for different checks for emails inside messages

-- Rules format:
-- symbol = sym, map = file:///path/to/file, domain_only = yes
-- symbol = sym2, dnsbl = bl.somehost.com, domain_only = no
local rules = {}
local logger = require "rspamd_logger"

-- Check rule for a single email
local function check_email_rule(task, rule, addr)
  local function emails_dns_cb(resolver, to_resolve, results, err)
    if results then
      logger.infox(task, '<%1> email: [%2] resolved for symbol: %3',
        task:get_message_id(), to_resolve, rule['symbol'])
      task:insert_result(rule['symbol'], 1)
    end
  end
  if rule['dnsbl'] then
    local to_resolve = ''
    if rule['domain_only'] then
      to_resolve = string.format('%s.%s', addr:get_host(), rule['dnsbl'])
    else
      to_resolve = string.format('%s.%s.%s', addr:get_user(), addr:get_host(), rule['dnsbl'])
    end
    
    task:get_resolver():resolve_a({
      task=task, 
      name = to_resolve, 
      callback = emails_dns_cb})
  elseif rule['map'] then
    if rule['domain_only'] then
      local key = addr:get_host()
      if rule['map']:get_key(key) then
        task:insert_result(rule['symbol'], 1)
        logger.infox(task, '<%1> email: \'%2\' is found in list: %3',
          task:get_message_id(), key, rule['symbol'])
      end
    else
      local key = string.format('%s@%s', addr:get_user(), addr:get_host())
      if rule['map']:get_key(key) then
        task:insert_result(rule['symbol'], 1)
        logger.infox(task, '<%1> email: \'%2\' is found in list: %3',
          task:get_message_id(), key, rule['symbol'])
      end
    end
  end
end

-- Check email
local function check_emails(task)
  local emails = task:get_emails()
  local checked = {}
  if emails then
    for _,addr in ipairs(emails) do
      local to_check = string.format('%s@%s', addr:get_user(), addr:get_host())
      if not checked['to_check'] then
        for _,rule in ipairs(rules) do
          check_email_rule(task, rule, addr)
        end
        checked[to_check] = true
      end 
    end
  end
end

local opts =  rspamd_config:get_all_opt('emails', 'rule')
if opts and type(opts) == 'table' then
  for k,v in pairs(opts) do
    if k == 'rule' and type(v) == 'table' then
      local rule = v
      if not rule['symbol'] then
        rule['symbol'] = k
      end
      if rule['map'] then
        rule['name'] = rule['map']
        rule['map'] = rspamd_config:add_hash_map (rule['name'])
      end
      if not rule['symbol'] or (not rule['map'] and not rule['dnsbl']) then
        logger.errx(rspamd_config, 'incomplete rule')
      else
        table.insert(rules, rule)
      end
    end
  end
end

if table.maxn(rules) > 0 then
  -- add fake symbol to check all maps inside a single callback
  local id = rspamd_config:register_callback_symbol(1.0, check_emails)
  for _,rule in ipairs(rules) do
    rspamd_config:register_virtual_symbol(rule['symbol'], 1.0, id)
  end
end