plugins/mod_scansion_record.lua
author Jonas Schäfer <jonas@wielicki.name>
Mon, 10 Jan 2022 18:23:54 +0100
branch0.11
changeset 12185 783056b4e448
parent 9623 7172077c0a53
child 10722 d229e4d31598
permissions -rw-r--r--
util.xml: Do not allow doctypes, comments or processing instructions Yes. This is as bad as it sounds. CVE pending. In Prosody itself, this only affects mod_websocket, which uses util.xml to parse the <open/> frame, thus allowing unauthenticated remote DoS using Billion Laughs. However, third-party modules using util.xml may also be affected by this. This commit installs handlers which disallow the use of doctype declarations and processing instructions without any escape hatch. It, by default, also introduces such a handler for comments, however, there is a way to enable comments nontheless. This is because util.xml is used to parse human-facing data, where comments are generally a desirable feature, and also because comments are generally harmless.

local names = { "Romeo", "Juliet", "Mercutio", "Tybalt", "Benvolio" };
local devices = { "", "phone", "laptop", "tablet", "toaster", "fridge", "shoe" };
local users = {};

local filters = require "util.filters";
local id = require "util.id";
local dt = require "util.datetime";
local dm = require "util.datamanager";
local st = require "util.stanza";

local record_id = id.medium():lower();
local record_date = os.date("%Y%b%d"):lower();
local header_file = dm.getpath(record_id, "scansion", record_date, "scs", true);
local record_file = dm.getpath(record_id, "scansion", record_date, "log", true);

local head = io.open(header_file, "w");
local scan = io.open(record_file, "w+");

local function record(string)
	scan:write(string);
end

local function record_header(string)
	head:write(string);
end

local function record_object(class, name, props)
	head:write(("[%s] %s\n"):format(class, name));
	for k,v in pairs(props) do
		head:write(("\t%s: %s\n"):format(k, v));
	end
	head:write("\n");
end

local function record_event(session, event)
	record(session.scansion_id.." "..event.."\n\n");
end

local function record_stanza(stanza, session, verb)
	local flattened = tostring(stanza):gsub("><", ">\n\t<");
	-- TODO Proper prettyprinting with indentation
	record(session.scansion_id.." "..verb..":\n\t"..flattened.."\n\n");
end

local function record_stanza_in(stanza, session)
	if stanza.attr.xmlns == nil then
		local copy = st.clone(stanza);
		copy.attr.from = nil;
		record_stanza(copy, session, "sends")
	end
	return stanza;
end

local function record_stanza_out(stanza, session)
	if stanza.attr.xmlns == nil then
		if not (stanza.name == "iq" and stanza:get_child("bind", "urn:ietf:params:xml:ns:xmpp-bind")) then
			local copy = st.clone(stanza);
			if copy.attr.to == session.full_jid then
				copy.attr.to = nil;
			end
			record_stanza(copy, session, "receives");
		end
	end
	return stanza;
end

module:hook("resource-bind", function (event)
	local session = event.session;
	if not users[session.username] then
		users[session.username] = {
			character = table.remove(names, 1) or id.short();
			devices = {};
			n_devices = 0;
		};
	end
	local user = users[session.username];
	local device = user.devices[session.resource];
	if not device then
		user.n_devices = user.n_devices + 1;
		device = devices[user.n_devices] or ("device"..id.short());
		user.devices[session.resource] = device;
	end
	session.scansion_character = user.character;
	session.scansion_device = device;
	session.scansion_id = user.character..(device ~= "" and "'s "..device or device);

	record_object("Client", session.scansion_id, {
		jid = session.full_jid,
		password = "password",
	});

	module:log("info", "Connected: %s", session.scansion_id);
	record_event(session, "connects");

	filters.add_filter(session, "stanzas/in", record_stanza_in);
	filters.add_filter(session, "stanzas/out", record_stanza_out);
end);

module:hook("resource-unbind", function (event)
	local session = event.session;
	if session.scansion_id then
		record_event(session, "disconnects");
	end
end)

record_header("# mod_scansion_record on host '"..module.host.."' recording started "..dt.datetime().."\n\n");

record[[
-----

]]

module:hook_global("server-stopping", function ()
	record("# recording ended on "..dt.datetime().."\n");
	module:log("info", "Scansion recording available in %s", header_file);
end);

prosody.events.add_handler("server-cleanup", function ()
	scan:seek("set", 0);
	for line in scan:lines() do
		head:write(line, "\n");
	end
	scan:close();
	os.remove(record_file);
	head:close()
end);