diff options
Diffstat (limited to 'lualib/lua_mime.lua')
| -rw-r--r-- | lualib/lua_mime.lua | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/lualib/lua_mime.lua b/lualib/lua_mime.lua index 795a803e5..1135f2b63 100644 --- a/lualib/lua_mime.lua +++ b/lualib/lua_mime.lua @@ -897,4 +897,282 @@ exports.remove_attachments = function(task, settings) return state end +--[[[ +-- @function lua_mime.get_displayed_text_part(task) +-- Returns the most relevant displayed content from an email +-- @param {task} task Rspamd task object +-- @return {text_part} a selected part +--]] +exports.get_displayed_text_part = function(task) + local text_parts = task:get_text_parts() + if not text_parts then + return nil + end + + local html_part + local text_part + local html_attachment + + -- First pass: categorize parts + for _, part in ipairs(text_parts) do + local mp = part:get_mimepart() + if not mp:is_attachment() then + if part:is_html() then + html_part = part + else + text_part = text_part or part + end + else + -- Check for HTML attachments + if part:is_html() and mp:get_length() < 102400 then + -- 100KB limit, as long ones are likely not something that we should check + html_attachment = part + end + end + end + + -- Decision logic + if html_part then + local word_count = html_part:get_words_count() or 0 + if word_count >= 10 then + -- Arbitrary minimum threshold, e.g. I believe it's minimum sane + return html_part + end + end + + if text_part then + local word_count = text_part:get_words_count() or 0 + if word_count >= 10 then + -- Arbitrary minimum threshold, e.g. I believe it's minimum sane + return text_part + end + end + + if html_attachment then + return html_attachment + end + + -- Only short parts, but still let's try our best + return html_part or text_part +end + +--[[[ +-- @function lua_mime.anonymize_message(task, settings) +-- Anonymizes message content by replacing sensitive data +-- @param {task} task Rspamd task object +-- @param {table} settings Table with the following fields: +-- * strip_attachments: boolean, whether to strip all attachments +-- * custom_header_process: table of header_name => function(orig_header) pairs +-- @return {table} modified message state similar to other modification functions +--]] +exports.anonymize_message = function(task, settings) + local rspamd_re = require "rspamd_regexp" + local lua_util = require "lua_util" + -- We exclude words with digits, currency symbols and so on + local exclude_words_re = rspamd_re.create_cached([=[/^(?:\d+|\d+\D{1,3}|\p{Sc}.*|(\+?\d{1,3}[\s\-]?)?)$/(:?^[[:alpha:]]*\d{4,}.*$)/u]=]) + local newline_s = newline(task) + local state = { + newline_s = newline_s + } + local out = {} + + -- Default header processors + local function anonymize_email_header(hdr) + local addrs = rspamd_util.parse_mail_address(hdr.value, task:get_mempool()) + if addrs and addrs[1] then + local modified = {} + for _, addr in ipairs(addrs) do + table.insert(modified, string.format('anonymous@%s', addr.domain or 'example.com')) + end + + return table.concat(modified, ',') + end + return 'anonymous@example.com' + end + + local function anonymize_received_header(hdr) + local processed = string.gsub(hdr.value, '%d+%.%d+%.%d+%.%d+', 'x.x.x.x') + processed = string.gsub(processed, '%x+:%x+:%x+:%x+:%x+:%x+:%x+:%x+', 'x:x:x:x:x:x:x:x') + return processed + end + + local default_header_process = { + ['from'] = anonymize_email_header, + ['to'] = anonymize_email_header, + ['cc'] = anonymize_email_header, + ['bcc'] = anonymize_email_header, + ['received'] = anonymize_received_header, + } + + -- Merge with custom processors + local header_processors = settings.custom_header_process or {} + for k, v in pairs(default_header_process) do + if not header_processors[k] then + header_processors[k] = v + end + end + + -- Process headers + local all_include = true + local all_exclude = false + + -- Convert strings list to a list of globs where possible + local function process_exceptions_list(list) + if list and #list > 0 then + for i, hdr in ipairs(list) do + local gl = rspamd_re.import_glob(hdr, 'i') + if gl then + list[i] = gl + end + end + return true + end + end + + local function maybe_match_header(hdr, list) + if not list then + return false + end + for _, expr in ipairs(list) do + if type(expr) == 'userdata' then + if expr:match(hdr) then + return true + end + else + if expr:lower() == hdr:lower() then + return true + end + end + end + return false + end + + if process_exceptions_list(settings.include_header) then + all_include = false + all_exclude = true + end + if process_exceptions_list(settings.exclude_header) then + all_exclude = true + end + + local modified_headers = {} + local function process_hdr(name, hdr) + local include_hdr = (all_include and not maybe_match_header(name, settings.exclude_header)) or + (all_exclude and maybe_match_header(name, settings.include_header)) + if include_hdr then + local processor = header_processors[name:lower()] + if processor then + local new_value = processor(hdr) + if new_value then + table.insert(modified_headers, { + name = name, + value = new_value + }) + end + else + table.insert(modified_headers, { + name = name, + value = hdr.value + }) + end + end + end + + task:headers_foreach(process_hdr, { full = true }) + + -- Create new text content + local text_content = {} + local urls = {} + local emails = {} + + local sel_part = exports.get_displayed_text_part(task) + + if sel_part then + text_content = sel_part:get_words('norm') + for i, w in ipairs(text_content) do + if exclude_words_re:match(w) then + text_content[i] = string.rep('x', #w) + end + end + end + + -- Process URLs + local function process_url(url) + local clean_url = url:get_host() + local path = url:get_path() + if path and path ~= "/" then + clean_url = string.format("%s/%s", clean_url, path) + end + return string.format('https://%s', clean_url) + end + + for _, url in ipairs(task:get_urls(true)) do + urls[process_url(url)] = true + end + + -- Process emails + local function process_email(email) + return string.format('nobody@%s', email.domain or 'example.com') + end + + for _, email in ipairs(task:get_emails()) do + emails[process_email(email)] = true + end + + -- Construct new message + table.insert(text_content, '\nurls:') + table.insert(text_content, table.concat(lua_util.keys(urls), ', ')) + table.insert(text_content, '\nemails:') + table.insert(text_content, table.concat(lua_util.keys(emails), ', ')) + local new_text = table.concat(text_content, ' ') + + -- Create new message structure + local cur_boundary = '--XXX' + + -- Add headers + out[#out + 1] = { + string.format('Content-Type: multipart/mixed; boundary="%s"', cur_boundary), + true + } + for _, hdr in ipairs(modified_headers) do + if hdr.name ~= 'Content-Type' then + out[#out + 1] = { + string.format('%s: %s', hdr.name, hdr.value), + true + } + end + end + out[#out + 1] = { '', true } + + -- Add text part + out[#out + 1] = { + string.format('--%s', cur_boundary), + true + } + out[#out + 1] = { + 'Content-Type: text/plain; charset=utf-8\nContent-Transfer-Encoding: quoted-printable', + true + } + out[#out + 1] = { '', true } + out[#out + 1] = { + rspamd_util.encode_qp(new_text, 76, task:get_newlines_type()), + true + } + + -- Close boundaries + out[#out + 1] = { + string.format('--%s--', cur_boundary), + true + } + + state.out = out + state.need_rewrite_ct = true + state.new_ct = { + type = 'multipart', + subtype = 'mixed' + } + + return state +end + return exports |