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--[[
Copyright (c) 2016, Steve Freegard <steve.freegard@fsl.com>
Copyright (c) 2016, Vsevolod Stakhov
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.
]]--
-- Check messages for 'bulkiness' using DCC
local symbol_bulk = "DCC_BULK"
local opts = rspamd_config:get_all_opt('dcc')
local logger = require "rspamd_logger"
local tcp = require "rspamd_tcp"
local fun = require "fun"
local function check_dcc (task)
-- Connection
local client = '0.0.0.0'
local client_ip = task:get_from_ip()
if client_ip and client_ip:is_valid() then
client = client_ip:to_string()
end
local client_host = task:get_hostname()
if client_host and client_host ~= 'unknown' then
client = client .. "\r" .. client_host
end
-- HELO
local helo = task:get_helo() or ''
-- Envelope From
local ef = task:get_from()
local envfrom = 'test@example.com'
if ef and ef[1] then
envfrom = ef[1]['addr']
end
-- Envelope To
local envrcpt = 'test@example.com'
local rcpts = task:get_recipients();
if rcpts then
local r = table.concat(fun.totable(fun.map(function(rcpt)
return rcpt['addr'] end,
rcpts)), '\n')
if r then
envrcpt = r
end
end
-- Callback function to receive async result from DCC
local function cb(err, data)
if (err) then
logger.warnx(task, 'DCC error: %1', err)
return
end
-- Parse the response
local _,_,result,disposition,header = tostring(data):find("(.-)\n(.-)\n(.-)\n")
logger.debugx(task, 'DCC result=%1 disposition=%2 header="%3"',
result, disposition, header)
if header then
local _,_,info = header:find("; (.-)$")
if (result == 'R') then
-- Reject
task:insert_result(symbol_bulk, 1.0, info)
elseif (result == 'T') then
-- Temporary failure
logger.warnx(task, 'DCC returned a temporary failure result')
else
if result ~= 'A' and result ~= 'G' and result ~= 'S' then
-- Unknown result
logger.warnx(task, 'DCC result error: %1', result);
end
end
end
end
-- Build the DCC query
-- https://www.dcc-servers.net/dcc/dcc-tree/dccifd.html#Protocol
local data = {
"header\n",
client .. "\n",
helo .. "\n",
envfrom .. "\n",
envrcpt .. "\n",
"\n",
task:get_content()
}
logger.debugx(task, 'sending to dcc: client=%1 helo="%2" envfrom="%3" envrcpt="%4"',
client, helo, envfrom, envrcpt)
tcp.request({
task = task,
host = opts['host'],
port = opts['port'] or 1,
shutdown = true,
data = data,
callback = cb
})
end
-- Configuration
if opts and opts['host'] then
rspamd_config:register_symbol({
name = symbol_bulk,
callback = check_dcc
})
rspamd_config:set_metric_symbol({
group = 'dcc',
score = 2.0,
description = 'Detected as bulk mail by DCC',
one_shot = true,
name = symbol_bulk
})
else
logger.infox('DCC module not configured');
end
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