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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.
]]--
--[[
external_relay plugin - sets IP/hostname from Received headers
]]--
if confighelp then
return
end
local lua_maps = require "lua_maps"
local lua_util = require "lua_util"
local rspamd_logger = require "rspamd_logger"
local ts = require("tableshape").types
local E = {}
local N = "external_relay"
local settings = {
rules = {},
}
local config_schema = ts.shape{
enabled = ts.boolean:is_optional(),
rules = ts.map_of(
ts.string, ts.one_of{
ts.shape{
priority = ts.number:is_optional(),
strategy = 'authenticated',
symbol = ts.string:is_optional(),
user_map = lua_maps.map_schema:is_optional(),
},
ts.shape{
count = ts.number,
priority = ts.number:is_optional(),
strategy = 'count',
symbol = ts.string:is_optional(),
},
ts.shape{
priority = ts.number:is_optional(),
strategy = 'local',
symbol = ts.string:is_optional(),
},
ts.shape{
hostname_map = lua_maps.map_schema,
priority = ts.number:is_optional(),
strategy = 'hostname_map',
symbol = ts.string:is_optional(),
},
}
),
}
local function set_from_rcvd(task, rcvd)
local rcvd_ip = rcvd.real_ip
if not (rcvd_ip and rcvd_ip:is_valid()) then
rspamd_logger.errx(task, 'no IP in header: %s', rcvd)
return
end
task:set_from_ip(rcvd_ip)
if rcvd.from_hostname then
task:set_hostname(rcvd.from_hostname)
task:set_helo(rcvd.from_hostname) -- use fake value for HELO
else
rspamd_logger.warnx(task, "couldn't get hostname from headers")
local ipstr = string.format('[%s]', rcvd_ip)
task:set_hostname(ipstr) -- returns nil from task:get_hostname()
task:set_helo(ipstr)
end
return true
end
local strategies = {}
strategies.authenticated = function(rule)
local user_map
if rule.user_map then
user_map = lua_maps.map_add_from_ucl(rule.user_map, 'set', 'external relay usernames')
if not user_map then
rspamd_logger.errx(rspamd_config, "couldn't add map %s; won't register symbol %s",
rule.user_map, rule.symbol)
return
end
end
return function(task)
local user = task:get_user()
if not user then
lua_util.debugm(N, task, 'sender is unauthenticated')
return
end
if user_map then
if not user_map:get_key(user) then
lua_util.debugm(N, task, 'sender (%s) is not in user_map', user)
return
end
end
local rcvd_hdrs = task:get_received_headers()
-- Try find end of authentication chain
for _, rcvd in ipairs(rcvd_hdrs) do
if not rcvd.flags.authenticated then
-- Found unauthenticated hop, use this header
return set_from_rcvd(task, rcvd)
end
end
rspamd_logger.errx(task, 'found nothing useful in Received headers')
end
end
strategies.count = function(rule)
return function(task)
local rcvd_hdrs = task:get_received_headers()
-- Reduce count by 1 if artificial header is present
local hdr_count
if ((rcvd_hdrs[1] or E).flags or E).artificial then
hdr_count = rule.count - 1
else
hdr_count = rule.count
end
local rcvd = rcvd_hdrs[hdr_count]
if not rcvd then
rspamd_logger.errx(task, 'found no received header #%s', hdr_count)
return
end
return set_from_rcvd(task, rcvd)
end
end
strategies.hostname_map = function(rule)
local hostname_map = lua_maps.map_add_from_ucl(rule.hostname_map, 'map', 'external relay hostnames')
if not hostname_map then
rspamd_logger.errx(rspamd_config, "couldn't add map %s; won't register symbol %s",
rule.hostname_map, rule.symbol)
return
end
return function(task)
local from_hn = task:get_hostname()
if not from_hn then
lua_util.debugm(N, task, 'sending hostname is missing')
return
end
local rcvd_hdrs = task:get_received_headers()
-- Try find sending hostname in Received headers
for _, rcvd in ipairs(rcvd_hdrs) do
if rcvd.by_hostname == from_hn and rcvd.real_ip then
if not hostname_map:get_key(rcvd.from_hostname) then
-- Remote hostname is not another relay, use this header
return set_from_rcvd(task, rcvd)
else
-- Keep checking with new hostname
from_hn = rcvd.from_hostname
end
end
end
rspamd_logger.errx(task, 'found nothing useful in Received headers')
end
end
strategies['local'] = function(rule)
return function(task)
local from_ip = task:get_from_ip()
if not from_ip then
lua_util.debugm(N, task, 'sending IP is missing')
return
end
if not from_ip:is_local() then
lua_util.debugm(N, task, 'sending IP (%s) is non-local', from_ip)
return
end
local rcvd_hdrs = task:get_received_headers()
local num_rcvd = #rcvd_hdrs
-- Try find first non-local IP in Received headers
for i, rcvd in ipairs(rcvd_hdrs) do
if rcvd.real_ip then
local rcvd_ip = rcvd.real_ip
if rcvd_ip and rcvd_ip:is_valid() and (not rcvd_ip:is_local() or i == num_rcvd) then
return set_from_rcvd(task, rcvd)
end
end
end
rspamd_logger.errx(task, 'found nothing useful in Received headers')
end
end
local opts = rspamd_config:get_all_opt(N)
if opts then
settings = lua_util.override_defaults(settings, opts)
local ok, schema_err = config_schema:transform(settings)
if not ok then
rspamd_logger.errx(rspamd_config, 'config schema error: %s', schema_err)
lua_util.disable_module(N, "config")
return
end
for k, rule in pairs(settings.rules) do
if not rule.symbol then
rule.symbol = k
end
local cb = strategies[rule.strategy](rule)
if cb then
rspamd_config:register_symbol({
name = rule.symbol,
type = 'prefilter',
priority = rule.priority or 20,
group = N,
callback = cb,
})
end
end
end
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