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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.
]]--
--[[[
-- @module lua_mime
-- This module contains helper functions to modify mime parts
--]]
local logger = require "rspamd_logger"
local rspamd_util = require "rspamd_util"
local rspamd_text = require "rspamd_text"
local ucl = require "ucl"
local exports = {}
local function newline(task)
local t = task:get_newlines_type()
if t == 'cr' then
return '\r'
elseif t == 'lf' then
return '\n'
end
return '\r\n'
end
local function do_append_footer(task, part, footer, is_multipart, out, state)
local tp = part:get_text()
local ct = 'text/plain'
local cte = 'quoted-printable'
local newline_s = state.newline_s
if tp:is_html() then
ct = 'text/html'
end
local encode_func = function(input)
return rspamd_util.encode_qp(input, 80, task:get_newlines_type())
end
if part:get_cte() == '7bit' then
cte = '7bit'
encode_func = function(input)
if type(input) == 'userdata' then
return input
else
return rspamd_text.fromstring(input)
end
end
end
if is_multipart then
out[#out + 1] = string.format('Content-Type: %s; charset=utf-8%s'..
'Content-Transfer-Encoding: %s',
ct, newline_s, cte)
out[#out + 1] = ''
else
state.new_cte = cte
end
local content = tp:get_content('raw_utf') or ''
local double_nline = newline_s .. newline_s
local nlen = #double_nline
-- Hack, if part ends with 2 newline, then we append it after footer
if content:sub(-(nlen), nlen + 1) == double_nline then
-- content without last newline
content = content:sub(-(#newline_s), #newline_s + 1) .. footer
out[#out + 1] = {encode_func(content), true}
out[#out + 1] = ''
else
content = content .. footer
out[#out + 1] = {encode_func(content), true}
out[#out + 1] = ''
end
end
--[[[
-- @function lua_mime.add_text_footer(task, html_footer, text_footer)
-- Adds a footer to all text parts in a message. It returns a table with the following
-- fields:
-- * out: new content (body only)
-- * need_rewrite_ct: boolean field that means if we must rewrite content type
-- * new_ct: new content type (type => string, subtype => string)
-- * new_cte: new content-transfer encoding (string)
--]]
exports.add_text_footer = function(task, html_footer, text_footer)
local newline_s = newline(task)
local state = {
newline_s = newline_s
}
local out = {}
local text_parts = task:get_text_parts()
if not (html_footer or text_footer) or not (text_parts and #text_parts > 0) then
return false
end
if html_footer or text_footer then
-- We need to take extra care about content-type and cte
local ct = task:get_header('Content-Type')
if ct then
ct = rspamd_util.parse_content_type(ct, task:get_mempool())
end
if ct then
if ct.type and ct.type == 'text' then
if ct.subtype then
if html_footer and (ct.subtype == 'html' or ct.subtype == 'htm') then
state.need_rewrite_ct = true
elseif text_footer and ct.subtype == 'plain' then
state.need_rewrite_ct = true
end
else
if text_footer then
state.need_rewrite_ct = true
end
end
state.new_ct = ct
end
else
if text_parts then
if #text_parts == 1 then
state.need_rewrite_ct = true
state.new_ct = {
type = 'text',
subtype = 'plain'
}
elseif #text_parts > 1 then
-- XXX: in fact, it cannot be
state.new_ct = {
type = 'multipart',
subtype = 'mixed'
}
end
end
end
end
local boundaries = {}
local cur_boundary
for _,part in ipairs(task:get_parts()) do
local boundary = part:get_boundary()
if part:is_multipart() then
if cur_boundary then
out[#out + 1] = string.format('--%s',
boundaries[#boundaries])
end
boundaries[#boundaries + 1] = boundary or '--XXX'
cur_boundary = boundary
local rh = part:get_raw_headers()
if #rh > 0 then
out[#out + 1] = {rh, true}
end
elseif part:is_message() then
if boundary then
if cur_boundary and boundary ~= cur_boundary then
-- Need to close boundary
out[#out + 1] = string.format('--%s--%s',
boundaries[#boundaries], newline_s)
table.remove(boundaries)
cur_boundary = nil
end
out[#out + 1] = string.format('--%s',
boundary)
end
out[#out + 1] = {part:get_raw_headers(), true}
else
local append_footer = false
local skip_footer = part:is_attachment()
local parent = part:get_parent()
if parent then
local t,st = parent:get_type()
if t == 'multipart' and st == 'signed' then
-- Do not modify signed parts
skip_footer = true
end
end
if text_footer and part:is_text() then
local tp = part:get_text()
if not tp:is_html() then
append_footer = text_footer
end
end
if html_footer and part:is_text() then
local tp = part:get_text()
if tp:is_html() then
append_footer = html_footer
end
end
if boundary then
if cur_boundary and boundary ~= cur_boundary then
-- Need to close boundary
out[#out + 1] = string.format('--%s--%s',
boundaries[#boundaries], newline_s)
table.remove(boundaries)
cur_boundary = boundary
end
out[#out + 1] = string.format('--%s',
boundary)
end
if append_footer and not skip_footer then
do_append_footer(task, part, append_footer,
parent and parent:is_multipart(), out, state)
else
out[#out + 1] = {part:get_raw_headers(), true}
out[#out + 1] = {part:get_raw_content(), false}
end
end
end
-- Close remaining
local b = table.remove(boundaries)
while b do
out[#out + 1] = string.format('--%s--', b)
if #boundaries > 0 then
out[#out + 1] = ''
end
b = table.remove(boundaries)
end
state.out = out
return state
end
local function do_replacement (task, part, mp, replacements,
is_multipart, out, state)
local tp = part:get_text()
local ct = 'text/plain'
local cte = 'quoted-printable'
local newline_s = state.newline_s
if tp:is_html() then
ct = 'text/html'
end
local encode_func = function(input)
return rspamd_util.encode_qp(input, 80, task:get_newlines_type())
end
if part:get_cte() == '7bit' then
cte = '7bit'
encode_func = function(input)
if type(input) == 'userdata' then
return input
else
return rspamd_text.fromstring(input)
end
end
end
local content = tp:get_content('raw_utf') or rspamd_text.fromstring('')
local match_pos = mp:match(content, true)
if match_pos then
-- sort matches and form the table:
-- start .. end for inclusion position
local matches_flattened = {}
for npat,matches in pairs(match_pos) do
for _,m in ipairs(matches) do
table.insert(matches_flattened, {m, npat})
end
end
-- Handle the case of empty match
if #matches_flattened == 0 then
out[#out + 1] = {part:get_raw_headers(), true}
out[#out + 1] = {part:get_raw_content(), false}
return
end
if is_multipart then
out[#out + 1] = {string.format('Content-Type: %s; charset="utf-8"%s'..
'Content-Transfer-Encoding: %s',
ct, newline_s, cte), true}
out[#out + 1] = {'', true}
else
state.new_cte = cte
end
state.has_matches = true
-- now sort flattened by start of match and eliminate all overlaps
table.sort(matches_flattened, function(m1, m2) return m1[1][1] < m2[1][1] end)
for i=1,#matches_flattened - 1 do
local st = matches_flattened[i][1][1] -- current start of match
local e = matches_flattened[i][1][2] -- current end of match
local max_npat = matches_flattened[i][2]
for j=i+1,#matches_flattened do
if matches_flattened[j][1][1] == st then
-- overlap
if matches_flattened[j][1][2] > e then
-- larger exclusion and switch replacement
e = matches_flattened[j][1][2]
max_npat = matches_flattened[j][2]
end
else
break
end
end
-- Maximum overlap for all matches
for j=i,#matches_flattened do
if matches_flattened[j][1][1] == st then
if e > matches_flattened[j][1][2] then
matches_flattened[j][1][2] = e
matches_flattened[j][2] = max_npat
end
else
break
end
end
end
-- Off-by one: match returns 0 based positions while we use 1 based in Lua
for _,m in ipairs(matches_flattened) do
m[1][1] = m[1][1] + 1
m[1][2] = m[1][2] + 1
end
-- Now flattened match table is sorted by start pos and has the maximum overlapped pattern
-- Matches with the same start and end are covering the same replacement
-- e.g. we had something like [1 .. 2] -> replacement 1 and [1 .. 4] -> replacement 2
-- after flattening we should have [1 .. 4] -> 2 and [1 .. 4] -> 2
-- we can safely ignore those duplicates in the following code
local cur_start = 1
local fragments = {}
for _,m in ipairs(matches_flattened) do
if m[1][1] >= cur_start then
fragments[#fragments + 1] = content:sub(cur_start, m[1][1] - 1)
fragments[#fragments + 1] = replacements[m[2]]
cur_start = m[1][2] -- end of match
end
end
-- last part
if cur_start < #content then
fragments[#fragments + 1] = content:span(cur_start)
end
-- Final stuff
out[#out + 1] = {encode_func(rspamd_text.fromtable(fragments)), false}
else
-- No matches
out[#out + 1] = {part:get_raw_headers(), true}
out[#out + 1] = {part:get_raw_content(), false}
end
end
--[[[
-- @function lua_mime.multipattern_text_replace(task, mp, replacements)
-- Replaces text according to multipattern matches. It returns a table with the following
-- fields:
-- * out: new content (body only)
-- * need_rewrite_ct: boolean field that means if we must rewrite content type
-- * new_ct: new content type (type => string, subtype => string)
-- * new_cte: new content-transfer encoding (string)
--]]
exports.multipattern_text_replace = function(task, mp, replacements)
local newline_s = newline(task)
local state = {
newline_s = newline_s
}
local out = {}
local text_parts = task:get_text_parts()
if not mp or not (text_parts and #text_parts > 0) then
return false
end
-- We need to take extra care about content-type and cte
local ct = task:get_header('Content-Type')
if ct then
ct = rspamd_util.parse_content_type(ct, task:get_mempool())
end
if ct then
if ct.type and ct.type == 'text' then
state.need_rewrite_ct = true
state.new_ct = ct
end
else
-- No explicit CT, need to guess
if text_parts then
if #text_parts == 1 then
state.need_rewrite_ct = true
state.new_ct = {
type = 'text',
subtype = 'plain'
}
elseif #text_parts > 1 then
-- XXX: in fact, it cannot be
state.new_ct = {
type = 'multipart',
subtype = 'mixed'
}
end
end
end
local boundaries = {}
local cur_boundary
for _,part in ipairs(task:get_parts()) do
local boundary = part:get_boundary()
if part:is_multipart() then
if cur_boundary then
out[#out + 1] = {string.format('--%s',
boundaries[#boundaries]), true}
end
boundaries[#boundaries + 1] = boundary or '--XXX'
cur_boundary = boundary
local rh = part:get_raw_headers()
if #rh > 0 then
out[#out + 1] = {rh, true}
end
elseif part:is_message() then
if boundary then
if cur_boundary and boundary ~= cur_boundary then
-- Need to close boundary
out[#out + 1] = {string.format('--%s--',
boundaries[#boundaries]), true}
table.remove(boundaries)
cur_boundary = nil
end
out[#out + 1] = {string.format('--%s',
boundary), true}
end
out[#out + 1] = {part:get_raw_headers(), true}
else
local skip_replacement = part:is_attachment()
local parent = part:get_parent()
if parent then
local t,st = parent:get_type()
if t == 'multipart' and st == 'signed' then
-- Do not modify signed parts
skip_replacement = true
end
end
if not part:is_text() then
skip_replacement = true
end
if boundary then
if cur_boundary and boundary ~= cur_boundary then
-- Need to close boundary
out[#out + 1] = {string.format('--%s--',
boundaries[#boundaries]), true}
table.remove(boundaries)
cur_boundary = boundary
end
out[#out + 1] = {string.format('--%s',
boundary), true}
end
if not skip_replacement then
do_replacement(task, part, mp, replacements,
parent and parent:is_multipart(), out, state)
else
-- Append as is
out[#out + 1] = {part:get_raw_headers(), true}
out[#out + 1] = {part:get_raw_content(), false}
end
end
end
-- Close remaining
local b = table.remove(boundaries)
while b do
out[#out + 1] = {string.format('--%s--', b), true}
if #boundaries > 0 then
out[#out + 1] = {'', true}
end
b = table.remove(boundaries)
end
state.out = out
return state
end
--[[[
-- @function lua_mime.modify_headers(task, {add = {hname = {value = 'value', order = 1}}, remove = {hname = {1,2}}})
-- Adds/removes headers both internal and in the milter reply
--]]
exports.modify_headers = function(task, hdr_alterations)
local add = hdr_alterations.add or {}
local remove = hdr_alterations.remove or {}
local add_headers = {} -- For Milter reply
local hdr_flattened = {} -- For C API
local function flatten_add_header(hname, hdr)
if not add_headers[hname] then
add_headers[hname] = {}
end
if not hdr_flattened[hname] then
hdr_flattened[hname] = {add = {}}
end
local add_tbl = hdr_flattened[hname].add
if hdr.value then
table.insert(add_headers[hname], {
order = (tonumber(hdr.order) or -1),
value = hdr.value,
})
table.insert(add_tbl, {tonumber(hdr.order) or -1, hdr.value})
elseif type(hdr) == 'table' then
for _,v in ipairs(hdr) do
flatten_add_header(hname, v)
end
elseif type(hdr) == 'string' then
table.insert(add_headers[hname], {
order = -1,
value = hdr,
})
table.insert(add_tbl, {-1, hdr})
else
logger.errx(task, 'invalid modification of header: %s', hdr)
end
end
if hdr_alterations.order then
-- Get headers alterations ordered
for _,hname in ipairs(hdr_alterations.order) do
flatten_add_header(hname, add[hname])
end
else
for hname,hdr in pairs(add) do
flatten_add_header(hname, hdr)
end
end
for hname,hdr in pairs(remove) do
if not hdr_flattened[hname] then
hdr_flattened[hname] = {remove = {}}
end
if not hdr_flattened[hname].remove then
hdr_flattened[hname].remove = {}
end
local remove_tbl = hdr_flattened[hname].remove
if type(hdr) == 'number' then
table.insert(remove_tbl, hdr)
else
for _,num in ipairs(hdr) do
table.insert(remove_tbl, num)
end
end
end
task:set_milter_reply({
add_headers = add_headers,
remove_headers = hdr_alterations.remove
})
for hname,flat_rules in pairs(hdr_flattened) do
task:modify_header(hname, flat_rules)
end
end
--[[[
-- @function lua_mime.message_to_ucl(task, [stringify_content])
-- Exports a message to an ucl object
--]]
exports.message_to_ucl = function(task, stringify_content)
local E = {}
local maybe_stringify_f = stringify_content and
tostring or function(t) return t end
local result = {
size = task:get_size(),
digest = task:get_digest(),
newlines = task:get_newlines_type(),
headers = task:get_headers(true)
}
-- Utility to convert ip addr to a string or nil if invalid/absent
local function maybe_stringify_ip(addr)
if addr and addr:is_valid() then
return addr:to_string()
end
return nil
end
-- Envelope (smtp) information from email (nil if empty)
result.envelope = {
from_smtp = (task:get_from('smtp') or E)[1],
recipients_smtp = task:get_recipients('smtp'),
helo = task:get_helo(),
hostname = task:get_hostname(),
client_ip = maybe_stringify_ip(task:get_client_ip()),
from_ip = maybe_stringify_ip(task:get_from_ip()),
}
if not next(result.envelope) then
result.envelope = ucl.null
end
local parts = task:get_parts() or E
result.parts = {}
for _,part in ipairs(parts) do
if not part:is_multipart() and not part:is_message() then
local p = {
size = part:get_length(),
type = string.format('%s/%s', part:get_type()),
detected_type = string.format('%s/%s', part:get_detected_type()),
filename = part:get_filename(),
content = maybe_stringify_f(part:get_content()),
headers = part:get_headers(true) or E,
boundary = part:get_enclosing_boundary(),
}
table.insert(result.parts, p)
else
-- Service part: multipart container or message/rfc822
local p = {
type = string.format('%s/%s', part:get_type()),
headers = part:get_headers(true) or E,
boundary = part:get_enclosing_boundary(),
size = 0,
}
if part:is_multipart() then
p.multipart_boundary = part:get_boundary()
end
table.insert(result.parts, p)
end
end
return result
end
--[[[
-- @function lua_mime.message_to_ucl_schema()
-- Returns schema for a message to verify result/document fields
--]]
exports.message_to_ucl_schema = function()
local ts = require("tableshape").types
local function headers_schema()
return ts.shape{
order = ts.integer:describe('Header order in a message'),
raw = ts.string:describe('Raw header value'):is_optional(),
empty_separator = ts.boolean:describe('Whether header has an empty separator'),
separator = ts.string:describe('Separator between a header and a value'),
decoded = ts.string:describe('Decoded value'):is_optional(),
value = ts.string:describe('Decoded value'):is_optional(),
name = ts.string:describe('Header name'),
tab_separated = ts.boolean:describe('Whether header has tab as a separator')
}
end
local function part_schema()
return ts.shape{
content = ts.string:describe('Decoded content'):is_optional(),
multipart_boundary = ts.string:describe('Multipart service boundary'):is_optional(),
size = ts.integer:describe('Size of the part'),
type = ts.string:describe('Announced type'):is_optional(),
detected_type = ts.string:describe('Detected type'):is_optional(),
boundary = ts.string:describe('Eclosing boundary'):is_optional(),
filename = ts.string:describe('File name for attachments'):is_optional(),
headers = ts.array_of(headers_schema()):describe('Part headers'),
}
end
local function email_addr_schema()
return ts.shape{
addr = ts.string:describe('Parsed address'):is_optional(),
raw = ts.string:describe('Raw address'),
flags = ts.shape{
valid = ts.boolean:describe('Valid address'):is_optional(),
ip = ts.boolean:describe('IP like address'):is_optional(),
braced = ts.boolean:describe('Have braces around address'):is_optional(),
quoted = ts.boolean:describe('Have quotes around address'):is_optional(),
empty = ts.boolean:describe('Empty address'):is_optional(),
backslash = ts.boolean:describe('Backslash in address'):is_optional(),
['8bit'] = ts.boolean:describe('8 bit characters in address'):is_optional(),
},
user = ts.string:describe('Parsed user part'):is_optional(),
name = ts.string:describe('Displayed name'):is_optional(),
domain = ts.string:describe('Parsed domain part'):is_optional(),
}
end
local function envelope_schema()
return ts.shape{
from_smtp = email_addr_schema():describe('SMTP from'):is_optional(),
recipients_smtp = ts.array_of(email_addr_schema()):describe('SMTP recipients'):is_optional(),
helo = ts.string:describe('SMTP Helo'):is_optional(),
hostname = ts.string:describe('Sender hostname'):is_optional(),
client_ip = ts.string:describe('Client ip'):is_optional(),
from_ip = ts.string:describe('Sender ip'):is_optional(),
}
end
return ts.shape{
headers = ts.array_of(headers_schema()),
parts = ts.array_of(part_schema()),
digest = ts.pattern(string.format('^%s$', string.rep('%x', 32)))
:describe('Message digest'),
newlines = ts.one_of({"cr", "lf", "crlf"}):describe('Newlines type'),
size = ts.integer:describe('Size of the message in bytes'),
envelope = envelope_schema()
}
end
return exports
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