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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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