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--[[
Copyright (c) 2011-2017, Vsevolod Stakhov <vsevolod@highsecure.ru>
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.
]]--
-- Emails is module for different checks for emails inside messages
if confighelp then
return
end
-- 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"
local hash = require "rspamd_cryptobox_hash"
local rspamd_lua_utils = require "lua_util"
local util = require "rspamd_util"
local N = "emails"
-- Check rule for a single email
local function check_email_rule(task, rule, addr)
if rule['whitelist'] then
if rule['whitelist']:get_key(addr.addr)
or rule['whitelist']:get_key(addr.domain) then
logger.debugm(N, task, "whitelisted address: %s", addr.addr)
return
end
end
if rule['dnsbl'] then
local email
local to_resolve
if rule['domain_only'] then
email = addr.domain
else
email = string.format('%s%s%s', addr.user, rule.delimiter, addr.domain)
end
local function emails_dns_cb(_, _, results, err)
if err and (err ~= 'requested record is not found'
and err ~= 'no records with this name') then
logger.errx(task, 'Error querying DNS: %1', err)
elseif results then
local expected_found = false
if rule['expect_ip'] then
for _,result in pairs(results) do
local ipstr = result:to_string()
if ipstr == rule['expect_ip'] then
expected_found = true
end
end
else
expected_found = true -- Accept any result
end
if expected_found then
if rule['hash'] then
task:insert_result(rule['symbol'], 1.0, {email, to_resolve})
else
task:insert_result(rule['symbol'], 1.0, email)
end
end
end
end
logger.debugm(N, task, "check %s on %s", email, rule['dnsbl'])
if rule['hash'] then
local hkey = hash.create_specific(rule['hash'], email)
if rule['encoding'] == 'base32' then
to_resolve = hkey:base32()
else
to_resolve = hkey:hex()
end
if rule['hashlen'] and type(rule['hashlen']) == 'number' then
if #to_resolve > rule['hashlen'] then
to_resolve = string.sub(to_resolve, 1, rule['hashlen'])
end
end
else
to_resolve = email
end
local dns_arg = string.format('%s.%s', to_resolve, rule['dnsbl'])
logger.debugm(N, task, "query %s", dns_arg)
task:get_resolver():resolve_a({
task=task,
name = dns_arg,
callback = emails_dns_cb})
elseif rule['map'] then
if rule['domain_only'] then
local key = addr.domain
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%s', addr.user, rule.delimiter, addr.domain)
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 gen_check_emails(rule)
return function(task)
local emails = task:get_emails()
local checked = {}
if emails and not rule.skip_body then
for _,addr in ipairs(emails) do
local to_check = string.format('%s%s%s', addr:get_user(),
rule.delimiter, addr:get_host())
local naddr = {
user = (addr:get_user() or ''):lower(),
domain = (addr:get_host() or ''):lower(),
addr = to_check:lower()
}
rspamd_lua_utils.remove_email_aliases(naddr)
if not checked[naddr.addr] then
check_email_rule(task, rule, naddr)
checked[naddr.addr] = true
end
end
end
if rule.check_replyto then
local function get_raw_header(name)
return ((task:get_header_full(name) or {})[1] or {})['value']
end
local replyto = get_raw_header('Reply-To')
if not replyto then return false end
local rt = util.parse_mail_address(replyto, task:get_mempool())
if rt and rt[1] then
rspamd_lua_utils.remove_email_aliases(rt[1])
if not checked[rt[1].addr] then
check_email_rule(task, rule, rt[1])
checked[rt[1].addr] = true
end
end
end
end
end
local opts = rspamd_config:get_module_opt('emails', 'rules')
if opts and type(opts) == 'table' then
for k,v in pairs(opts) do
local rule = v
if not rule['symbol'] then
rule['symbol'] = k
end
if not rule['delimiter'] then
rule['delimiter'] = "@"
end
if rule['whitelist'] then
rule['whitelist'] = rspamd_config:add_map({
url = rule['whitelist'],
description = string.format('Emails rule %s whitelist', rule['symbol']),
type = 'set'
})
end
if rule['map'] then
rule['name'] = rule['map']
rule['map'] = rspamd_config:add_map({
url = rule['name'],
description = string.format('Emails rule %s', rule['symbol']),
type = 'regexp'
})
end
if not rule['symbol'] or (not rule['map'] and not rule['dnsbl']) then
logger.errx(rspamd_config, 'incomplete rule: %s', rule)
else
table.insert(rules, rule)
logger.infox(rspamd_config, 'add emails rule %s',
rule['dnsbl'] or rule['name'] or '???')
end
end
end
if #rules > 0 then
for _,rule in ipairs(rules) do
local cb = gen_check_emails(rule)
rspamd_config:register_symbol({
name = rule['symbol'],
callback = cb,
})
end
else
rspamd_lua_utils.disable_module(N, "conf")
end
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