--[[
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.
]]--

-- Module for checking mail list headers

local symbol = 'MAILLIST'
local rspamd_logger = require "rspamd_logger"
-- EZMLM
-- Mailing-List: .*run by ezmlm
-- Precedence: bulk
-- List-Post: <mailto:
-- List-Help: <mailto:
-- List-Unsubscribe: <mailto:[a-zA-Z\.-]+-unsubscribe@
-- List-Subscribe: <mailto:[a-zA-Z\.-]+-subscribe@
local function check_ml_ezmlm(task)
	-- Mailing-List
	local header = task:get_header('mailing-list')
	if not header or not string.find(header, 'ezmlm$') then
		return false
	end
	-- Precedence
	header = task:get_header('precedence')
	if not header or not string.match(header, '^bulk$') then
		return false
	end
	-- Other headers
	header = task:get_header('list-post')
	if not header or not string.find(header, '^<mailto:') then
		return false
	end
	header = task:get_header('list-help')
	if not header or not string.find(header, '^<mailto:') then
		return false
	end
	-- Subscribe and unsubscribe
	header = task:get_header('list-subscribe')
	if not header or not string.find(header, '<mailto:[a-zA-Z.-]+-subscribe@') then
		return false
	end
	header = task:get_header('list-unsubscribe')
	if not header or not string.find(header, '<mailto:[a-zA-Z.-]+-unsubscribe@') then
		return false
	end

	return true
end

-- MailMan (the gnu mailing list manager)
-- Precedence: bulk [or list for v2]
-- List-Help: <mailto:
-- List-Post: <mailto:
-- List-Subscribe: .*<mailto:.*=subscribe>
-- List-Id: 
-- List-Unsubscribe: .*<mailto:.*=unsubscribe>
-- List-Archive: 
-- X-Mailman-Version: \d
local function check_ml_mailman(task)
	-- Mailing-List
	local header = task:get_header('x-mailman-version')
	if not header or not string.find(header, '^%d') then
		return false
	end
	-- Precedence
	header = task:get_header('precedence')
	if not header or (not string.match(header, '^bulk$') and not string.match(header, '^list$')) then
		return false
	end
	-- For reminders we have other headers than for normal messages
	header = task:get_header('x-list-administrivia')
	local subject = task:get_header('subject')
	if (header and string.find(header, 'yes')) or (subject and string.find(subject, 'mailing list memberships reminder$')) then
		if not task:get_header('errors-to') or not task:get_header('x-beenthere') then
			return false
		end
		header = task:get_header('x-no-archive')
		if not header or not string.find(header, 'yes') then
			return false
		end
		return true
	end

	-- Other headers
	header = task:get_header('list-id')
	if not header then
		return false
	end
	header = task:get_header('list-post')
	if not header or not string.find(header, '^<mailto:') then
		return false
	end
	header = task:get_header('list-help')
	if not header or not string.find(header, '^<mailto:') then
		return false
	end
	-- Subscribe and unsubscribe
	header = task:get_header('list-subscribe')
	if not header or not string.find(header, '<mailto:.*=subscribe>') then
		return false
	end
	header = task:get_header('list-unsubscribe')
	if not header or not string.find(header, '<mailto:.*=unsubscribe>') then
		return false
	end

	return true

end

-- Subscribe.ru
-- Precedence: normal
-- List-Id: <.*.subscribe.ru>
-- List-Help: <http://subscribe.ru/catalog/.*>
-- List-Subscribe: <mailto:.*-sub@subscribe.ru>
-- List-Unsubscribe: <mailto:.*-unsub@subscribe.ru>
-- List-Archive:  <http://subscribe.ru/archive/.*>
-- List-Owner: <mailto:.*-owner@subscribe.ru>
-- List-Post: NO
local function check_ml_subscriberu(task)
	-- List-Id
	local header = task:get_header('list-id')
	if not header or not string.find(header, '^<.*%.subscribe%.ru>$') then
		return false
	end
	-- Precedence
	header = task:get_header('precedence')
	if not header or not string.match(header, '^normal$') then
		return false
	end
	-- Other headers
	header = task:get_header('list-archive')
	if not header or not string.find(header, '^<http://subscribe.ru/archive/.*>$') then
		return false
	end
	header = task:get_header('list-owner')
	if not header or not string.find(header, '^<mailto:.*-owner@subscribe.ru>$') then
		return false
	end
	header = task:get_header('list-help')
	if not header or not string.find(header, '^<http://subscribe.ru/catalog/.*>$') then
		return false
	end
	-- Subscribe and unsubscribe
	header = task:get_header('list-subscribe')
	if not header or not string.find(header, '^<mailto:.*-sub@subscribe.ru>$') then
		return false
	end
	header = task:get_header('list-unsubscribe')
	if not header or not string.find(header, '^<mailto:.*-unsub@subscribe.ru>$') then
		return false
	end

	return true

end

-- RFC 2369 headers
local function check_rfc2369(task)
	local header = task:get_header('List-Id')
	if not header then
		return false
	end
	header = task:get_header('List-Unsubscribe')
	if not header or not string.find(header, '^^<.+>$') then
		return false
	end
	header = task:get_header('List-Subscribe')
	if not header or not string.find(header, '^^<.+>$') then
		return false
	end
	
	return true
end

-- RFC 2919 headers
local function check_rfc2919(task)
	local header = task:get_header('List-Id')
	if not header or not string.find(header, '^<.+>$') then
		return false
	end
	
	return check_rfc2369(task)
end

-- Google groups detector
-- header exists X-Google-Loop
-- RFC 2919 headers exist
--
local function check_ml_googlegroup(task)
	local header = task:get_header('X-Google-Loop')
	
	if not header then
		return false
	end

	return check_rfc2919(task)
end

-- Majordomo detector
-- Check Sender for owner- or -owner
-- Check Precendence for 'Bulk' or 'List'
--
-- And nothing more can be extracted :(
local function check_ml_majordomo(task)
	local header = task:get_header('Sender')
	if not header or (not string.find(header, '^owner-.*$') and not string.find(header, '^.*-owner$')) then
		return false
	end
	
	local header = task:get_header('Precedence')
	if not header or (header ~= 'list' and header ~= 'bulk') then
		return false
	end

	return true
end

-- CGP detector
-- X-Listserver = CommuniGate Pro LIST
-- RFC 2919 headers exist
--
local function check_ml_cgp(task)
	local header = task:get_header('X-Listserver')
	
	if not header or header ~= 'CommuniGate Pro LIST' then
		return false
	end

	return check_rfc2919(task)
end

local function check_maillist(task)
	if check_ml_ezmlm(task) then
		task:insert_result(symbol, 1, 'ezmlm')
	elseif check_ml_mailman(task) then
		task:insert_result(symbol, 1, 'mailman')
	elseif check_ml_subscriberu(task) then
		task:insert_result(symbol, 1, 'subscribe.ru')
	elseif check_ml_googlegroup(task) then
		task:insert_result(symbol, 1, 'googlegroups')
	elseif check_ml_majordomo(task) then
		task:insert_result(symbol, 1, 'majordomo')
	elseif check_ml_cgp(task) then
		task:insert_result(symbol, 1, 'cgp')
	end
end
-- Registration
if type(rspamd_config.get_api_version) ~= 'nil' then
	if rspamd_config:get_api_version() >= 1 then
		rspamd_config:register_module_option('maillist', 'symbol', 'string')
	end
end
-- Configuration
local opts =  rspamd_config:get_all_opt('maillist')if opts then
	if opts['symbol'] then
		symbol = opts['symbol'] 
		rspamd_config:register_symbol(symbol, 1.0, check_maillist)
	end
end