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--[[
Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com>
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
-- Module for checking mail list headers
local N = 'maillist'
local symbol = 'MAILLIST'
local lua_util = require "lua_util"
-- 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@
-- RFC 2919 headers exist
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
-- GNU Mailman
-- Two major versions currently in use and they use slightly different headers
-- Mailman2: https://code.launchpad.net/~mailman-coders/mailman/2.1
-- Mailman3: https://gitlab.com/mailman/mailman
local function check_ml_mailman(task)
local header = task:get_header('X-Mailman-Version')
if not header then
return false
end
local mm_version = header:match('^([23])%.')
if not mm_version then
lua_util.debugm(N, task, 'unknown Mailman version: %s', header)
return false
end
lua_util.debugm(N, task, 'checking Mailman %s headers', mm_version)
-- XXX Some messages may not contain Precedence, but they are rare:
-- http://bazaar.launchpad.net/~mailman-coders/mailman/2.1/revision/1339
header = task:get_header('Precedence')
if not header or (header ~= 'bulk' and header ~= 'list') then
return false
end
-- Mailman 3 allows to disable all List-* headers in settings, but by default it adds them.
-- In all other cases all Mailman message should have List-Id header
if not task:has_header('List-Id') then
return false
end
if mm_version == '2' then
-- X-BeenThere present in all Mailman2 messages
if not task:has_header('X-BeenThere') then
return false
end
-- X-List-Administrivia: is only added to messages Mailman creates and
-- sends out of its own accord
header = task:get_header('X-List-Administrivia')
if header and header == 'yes' then
-- not much elase we can check, Subjects can be changed in settings
return true
end
else
-- Mailman 3
-- XXX not Mailman3 admin messages have this headers, but one
-- which don't usually have List-* headers examined below
if task:has_header('List-Administrivia') then
return true
end
end
-- List-Archive and List-Post are optional, check other headers
for _, h in ipairs({ 'List-Help', 'List-Subscribe', 'List-Unsubscribe' }) do
header = task:get_header(h)
if not (header and header:find('<mailto:', 1, true)) then
return false
end
end
return true
end
-- Google groups detector
-- header exists X-Google-Loop
-- RFC 2919 headers exist
--
local function check_ml_googlegroup(task)
return task:has_header('X-Google-Loop') or task:has_header('X-Google-Group-Id')
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 string.sub(header, 0, 20) ~= 'CommuniGate Pro LIST' then
return false
end
return true
end
-- RFC 2919 headers
local function check_generic_list_headers(task)
local score = 0
local has_subscribe, has_unsubscribe
local common_list_headers = {
['List-Id'] = 0.75,
['List-Archive'] = 0.125,
['List-Owner'] = 0.125,
['List-Help'] = 0.125,
['List-Post'] = 0.125,
['X-Loop'] = 0.125,
['List-Subscribe'] = function()
has_subscribe = true
return 0.125
end,
['List-Unsubscribe'] = function()
has_unsubscribe = true
return 0.125
end,
['Precedence'] = function()
local header = task:get_header('Precedence')
if header and (header == 'list' or header == 'bulk') then
return 0.25
end
end,
}
for hname, hscore in pairs(common_list_headers) do
if task:has_header(hname) then
if type(hscore) == 'number' then
score = score + hscore
lua_util.debugm(N, task, 'has %s header, score = %s', hname, score)
else
local score_change = hscore()
if score and score_change then
score = score + score_change
lua_util.debugm(N, task, 'has %s header, score = %s', hname, score)
end
end
end
end
if has_subscribe and has_unsubscribe then
score = score + 0.25
end
lua_util.debugm(N, task, 'final maillist score %s', score)
return score
end
-- RFC 2919 headers exist
local function check_maillist(task)
local score = check_generic_list_headers(task)
if score >= 1 then
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_googlegroup(task) then
task:insert_result(symbol, 1, 'googlegroups')
elseif check_ml_cgp(task) then
task:insert_result(symbol, 1, 'cgp')
else
if score > 2 then
score = 2
end
task:insert_result(symbol, 0.5 * score, 'generic')
end
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({
name = symbol,
callback = check_maillist,
flags = 'nice'
})
end
end
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