--[[
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.
]]--

-- This is main lua config file for rspamd

local util = require "rspamd_util"
local rspamd_regexp = require "rspamd_regexp"
local rspamd_logger = require "rspamd_logger"

local reconf = config['regexp']

-- Uncategorized rules
local subject_re = rspamd_regexp.create('/^(?:(?:Re|Fwd|Fw|Aw|Antwort|Sv):\\s*)+(.+)$/i')

-- Local rules
local r_bgcolor = '/BGCOLOR=/iP'
local r_font_color = '/font color=[\\"\']?\\#FFFFFF[\\"\']?/iP'
reconf['R_WHITE_ON_WHITE'] = string.format('(!(%s) & (%s))', r_bgcolor, r_font_color)
reconf['R_FLASH_REDIR_IMGSHACK'] = '/^(?:http:\\/\\/)?img\\d{1,5}\\.imageshack\\.us\\/\\S+\\.swf/U'

-- Different text parts
rspamd_config.R_PARTS_DIFFER = function(task)
  local distance = task:get_mempool():get_variable('parts_distance', 'int')

  if distance then
    local nd = tonumber(distance)

    if nd < 50 then
      local score = 1 - util.tanh(nd / 100.0)

      task:insert_result('R_PARTS_DIFFER', score, tostring(nd) .. '%')
    end
  end

  return false
end

-- Date issues
rspamd_config.MISSING_DATE = function(task)
	if rspamd_config:get_api_version() >= 5 then
		if not task:get_header_raw('Date') then
			return true
		end
	end

	return false
end
rspamd_config.DATE_IN_FUTURE = function(task)
	if rspamd_config:get_api_version() >= 5 then
		local dm = task:get_date{format = 'message'}
		local dt = task:get_date{format = 'connect'}
		-- An 2 hour
		if dm > 0 and dm - dt > 7200 then
			return true
		end
	end

	return false
end
rspamd_config.DATE_IN_PAST = function(task)
	if rspamd_config:get_api_version() >= 5 then
    local dm = task:get_date{format = 'message', gmt = true}
    local dt = task:get_date{format = 'connect', gmt = true}
		-- A day
		if dm > 0 and dt - dm > 86400 then
			return true
		end
	end

	return false
end

rspamd_config.R_SUSPICIOUS_URL = {
  callback = function(task)
    local urls = task:get_urls()

    if urls then
      for i,u in ipairs(urls) do
        if u:is_obscured() then
          return true
        end
      end
    end
    return false
  end,
  score = 6.0,
  group = 'url',
  one_shot = true,
  description = 'Obfusicated or suspicious URL has been found in a message'
}

rspamd_config.SUBJ_ALL_CAPS = {
  callback = function(task)
    local sbj = task:get_header('Subject')

    if sbj then
      local stripped_subject = subject_re:search(sbj, false, true)
      if stripped_subject and stripped_subject[1] and stripped_subject[1][2] then
        sbj = stripped_subject[1][2]
      end

      if util.is_uppercase(sbj) then
        return true
      end
    end

    return false
  end,
  score = 3.0,
  group = 'headers',
  description = 'All capital letters in subject'
}

rspamd_config.BROKEN_HEADERS = {
  callback = function(task)
    if task:has_flag('broken_headers') then
      return true
    end
    
    return false
  end,
  score = 1.0,
  group = 'headers',
  description = 'Headers structure is likely broken'
}

rspamd_config.HEADER_RCONFIRM_MISMATCH = {
  callback = function (task)
    local header_from  = task:get_from('mime')[1]
    local cread = task:get_header('X-Confirm-Reading-To')

    local header_cread = nil
    if cread then
      local headers_cread = util.parse_mail_address(cread)
      if headers_cread then header_cread = headers_cread[1] end
    end

    if header_from and header_cread then
      if not string.find(header_from['addr'], header_cread['addr']) then
        return true
      end
    end

    return false
  end,

  score = 2.0,
  group = 'headers',
  description = 'Read confirmation address is different to from address'
}

rspamd_config.HEADER_FORGED_MDN = {
  callback = function (task)
    local mdn = task:get_header('Disposition-Notification-To')
    local header_rp  = task:get_from('smtp')[1]

    -- Parse mail addr
    local header_mdn = nil
    if mdn then
      local headers_mdn = util.parse_mail_address(mdn)
      if headers_mdn then header_mdn = headers_mdn[1] end
    end

    if header_mdn and not header_rp  then return true end
    if header_rp  and not header_mdn then return true end

    if header_mdn['addr'] ~= header_rp['addr'] then
      return true
    end

    return false
  end,

  score = 2.0,
  group = 'headers',
  description = 'Read confirmation address is different to return path'
}

local headers_unique = {
  'Content-Type',
  'Content-Transfer-Encoding',
  'Date',
  'Message-ID'
}

rspamd_config.MULTIPLE_UNIQUE_HEADERS = {
  callback = function (task)
    local res = 0
    local res_tbl = {}
    
    for i,hdr in ipairs(headers_unique) do
      local h = task:get_header_full(hdr)
      
      if h and #h > 1 then
        res = res + 1
        table.insert(res_tbl, hdr)
      end
    end
    
    if res > 0 then
      return true,res,table.concat(res_tbl, ',')
    end
    
    return false
  end,

  score = 5.0,
  group = 'headers',
  description = 'Repeated unique headers'
}