view mod_firewall/conditions.lib.lua @ 5296:0f5657db1cfc

mod_isolate_host: handle server-generated stanzas The hook for setting the no_host_isolation is only called for c2s sessions. This does not work for stanzas generated by the server, such as PEP notifications or presence probe answers. To handle that, we do per-stanza checks for the case that the origin is local.
author Jonas Schäfer <jonas@wielicki.name>
date Sat, 01 Apr 2023 12:03:08 +0200
parents 84997bc3f92e
children 8226ac08484e
line wrap: on
line source

--luacheck: globals meta idsafe
local condition_handlers = {};

local jid = require "util.jid";
local unpack = table.unpack or unpack;

-- Helper to convert user-input strings (yes/true//no/false) to a bool
local function string_to_boolean(s)
	s = s:lower();
	return s == "yes" or s == "true";
end

-- Return a code string for a condition that checks whether the contents
-- of variable with the name 'name' matches any of the values in the
-- comma/space/pipe delimited list 'values'.
local function compile_comparison_list(name, values)
	local conditions = {};
	for value in values:gmatch("[^%s,|]+") do
		table.insert(conditions, ("%s == %q"):format(name, value));
	end
	return table.concat(conditions, " or ");
end

function condition_handlers.KIND(kind)
	assert(kind, "Expected stanza kind to match against");
	return compile_comparison_list("name", kind), { "name" };
end

local wildcard_equivs = { ["*"] = ".*", ["?"] = "." };

local function compile_jid_match_part(part, match)
	if not match then
		return part.." == nil";
	end
	local pattern = match:match("^<(.*)>$");
	if pattern then
		if pattern == "*" then
			return part;
		end
		if pattern:find("^<.*>$") then
			pattern = pattern:match("^<(.*)>$");
		else
			pattern = pattern:gsub("%p", "%%%0"):gsub("%%(%p)", wildcard_equivs);
		end
		return ("(%s and %s:find(%q))"):format(part, part, "^"..pattern.."$");
	else
		return ("%s == %q"):format(part, match);
	end
end

local function compile_jid_match(which, match_jid)
	local match_node, match_host, match_resource = jid.split(match_jid);
	local conditions = {};
	conditions[#conditions+1] = compile_jid_match_part(which.."_node", match_node);
	conditions[#conditions+1] = compile_jid_match_part(which.."_host", match_host);
	if match_resource then
		conditions[#conditions+1] = compile_jid_match_part(which.."_resource", match_resource);
	end
	return table.concat(conditions, " and ");
end

function condition_handlers.TO(to)
	return compile_jid_match("to", to), { "split_to" };
end

function condition_handlers.FROM(from)
	return compile_jid_match("from", from), { "split_from" };
end

function condition_handlers.FROM_EXACTLY(from)
	local metadeps = {};
	return ("from == %s"):format(metaq(from, metadeps)), { "from", unpack(metadeps) };
end

function condition_handlers.TO_EXACTLY(to)
	local metadeps = {};
	return ("to == %s"):format(metaq(to, metadeps)), { "to", unpack(metadeps) };
end

function condition_handlers.TO_SELF()
	-- Intentionally not using 'to' here, as that defaults to bare JID when nil
	return ("stanza.attr.to == nil");
end

function condition_handlers.TYPE(type)
	assert(type, "Expected 'type' value to match against");
	return compile_comparison_list("(type or (name == 'message' and 'normal') or (name == 'presence' and 'available'))", type), { "type", "name" };
end

local function zone_check(zone, which)
	local zone_var = zone;
	if zone == "$local" then zone_var = "_local" end
	local which_not = which == "from" and "to" or "from";
	return ("(zone_%s[%s_host] or zone_%s[%s] or zone_%s[bare_%s]) "
		.."and not(zone_%s[%s_host] or zone_%s[%s] or zone_%s[bare_%s])"
		)
		:format(zone_var, which, zone_var, which, zone_var, which,
		zone_var, which_not, zone_var, which_not, zone_var, which_not), {
			"split_to", "split_from", "bare_to", "bare_from", "zone:"..zone
		};
end

function condition_handlers.ENTERING(zone)
	return zone_check(zone, "to");
end

function condition_handlers.LEAVING(zone)
	return zone_check(zone, "from");
end

-- IN ROSTER? (parameter is deprecated)
function condition_handlers.IN_ROSTER(yes_no)
	local in_roster_requirement = string_to_boolean(yes_no or "yes"); -- COMPAT w/ older scripts
	return "not "..(in_roster_requirement and "not" or "").." roster_entry", { "roster_entry" };
end

function condition_handlers.IN_ROSTER_GROUP(group)
	return ("not not (roster_entry and roster_entry.groups[%q])"):format(group), { "roster_entry" };
end

function condition_handlers.SUBSCRIBED()
	return "(bare_to == bare_from or to_node and rostermanager.is_contact_subscribed(to_node, to_host, bare_from))",
	       { "rostermanager", "split_to", "bare_to", "bare_from" };
end

function condition_handlers.PENDING_SUBSCRIPTION_FROM_SENDER()
	return "(bare_to == bare_from or to_node and rostermanager.is_contact_pending_in(to_node, to_host, bare_from))",
	       { "rostermanager", "split_to", "bare_to", "bare_from" };
end

function condition_handlers.PAYLOAD(payload_ns)
	return ("stanza:get_child(nil, %q)"):format(payload_ns);
end

function condition_handlers.INSPECT(path)
	if path:find("=") then
		local query, match_type, value = path:match("(.-)([~/$]*)=(.*)");
		if not(query:match("#$") or query:match("@[^/]+")) then
			error("Stanza path does not return a string (append # for text content or @name for value of named attribute)", 0);
		end
		local meta_deps = {};
		local quoted_value = ("%q"):format(value);
		if match_type:find("$", 1, true) then
			match_type = match_type:gsub("%$", "");
			quoted_value = meta(quoted_value, meta_deps);
		end
		if match_type == "~" then -- Lua pattern match
			return ("(stanza:find(%q) or ''):match(%s)"):format(query, quoted_value), meta_deps;
		elseif match_type == "/" then -- find literal substring
			return ("(stanza:find(%q) or ''):find(%s, 1, true)"):format(query, quoted_value), meta_deps;
		elseif match_type == "" then -- exact match
			return ("stanza:find(%q) == %s"):format(query, quoted_value), meta_deps;
		else
			error("Unrecognised comparison '"..match_type.."='", 0);
		end
	end
	return ("stanza:find(%q)"):format(path);
end

function condition_handlers.FROM_GROUP(group_name)
	return ("group_contains(%q, bare_from)"):format(group_name), { "group_contains", "bare_from" };
end

function condition_handlers.TO_GROUP(group_name)
	return ("group_contains(%q, bare_to)"):format(group_name), { "group_contains", "bare_to" };
end

function condition_handlers.CROSSING_GROUPS(group_names)
	local code = {};
	for group_name in group_names:gmatch("([^, ][^,]+)") do
		group_name = group_name:match("^%s*(.-)%s*$"); -- Trim leading/trailing whitespace
		-- Just check that's it is crossing from outside group to inside group
		table.insert(code, ("(group_contains(%q, bare_to) and group_contains(%q, bare_from))"):format(group_name, group_name))
	end
	return "not "..table.concat(code, " or "), { "group_contains", "bare_to", "bare_from" };
end

-- COMPAT w/0.12: Deprecated
function condition_handlers.FROM_ADMIN_OF(host)
	return ("is_admin(bare_from, %s)"):format(host ~= "*" and metaq(host) or nil), { "is_admin", "bare_from" };
end

-- COMPAT w/0.12: Deprecated
function condition_handlers.TO_ADMIN_OF(host)
	return ("is_admin(bare_to, %s)"):format(host ~= "*" and metaq(host) or nil), { "is_admin", "bare_to" };
end

-- COMPAT w/0.12: Deprecated
function condition_handlers.FROM_ADMIN()
	return ("is_admin(bare_from, current_host)"), { "is_admin", "bare_from", "current_host" };
end

-- COMPAT w/0.12: Deprecated
function condition_handlers.TO_ADMIN()
	return ("is_admin(bare_to, current_host)"), { "is_admin", "bare_to", "current_host" };
end

-- MAY: permission_to_check
function condition_handlers.MAY(permission_to_check)
	return ("module:may(%q, event)"):format(permission_to_check);
end

function condition_handlers.TO_ROLE(role_name)
	return ("get_jid_role(bare_to, current_host) == %q"):format(role_name), { "get_jid_role", "current_host", "bare_to" };
end

function condition_handlers.FROM_ROLE(role_name)
	return ("get_jid_role(bare_from, current_host) == %q"):format(role_name), { "get_jid_role", "current_host", "bare_from" };
end

local day_numbers = { sun = 0, mon = 2, tue = 3, wed = 4, thu = 5, fri = 6, sat = 7 };

local function current_time_check(op, hour, minute)
	hour, minute = tonumber(hour), tonumber(minute);
	local adj_op = op == "<" and "<" or ">="; -- Start time inclusive, end time exclusive
	if minute == 0 then
		return "(current_hour"..adj_op..hour..")";
	else
		return "((current_hour"..op..hour..") or (current_hour == "..hour.." and current_minute"..adj_op..minute.."))";
	end
end

local function resolve_day_number(day_name)
	return assert(day_numbers[day_name:sub(1,3):lower()], "Unknown day name: "..day_name);
end

function condition_handlers.DAY(days)
	local conditions = {};
	for day_range in days:gmatch("[^,]+") do
		local day_start, day_end = day_range:match("(%a+)%s*%-%s*(%a+)");
		if day_start and day_end then
			local day_start_num, day_end_num = resolve_day_number(day_start), resolve_day_number(day_end);
			local op = "and";
			if day_end_num < day_start_num then
				op = "or";
			end
			table.insert(conditions, ("current_day >= %d %s current_day <= %d"):format(day_start_num, op, day_end_num));
		elseif day_range:find("%a") then
			local day = resolve_day_number(day_range:match("%a+"));
			table.insert(conditions, "current_day == "..day);
		else
			error("Unable to parse day/day range: "..day_range);
		end
	end
	assert(#conditions>0, "Expected a list of days or day ranges");
	return "("..table.concat(conditions, ") or (")..")", { "time:day" };
end

function condition_handlers.TIME(ranges)
	local conditions = {};
	for range in ranges:gmatch("([^,]+)") do
		local clause = {};
		range = range:lower()
			:gsub("(%d+):?(%d*) *am", function (h, m) return tostring(tonumber(h)%12)..":"..(tonumber(m) or "00"); end)
			:gsub("(%d+):?(%d*) *pm", function (h, m) return tostring(tonumber(h)%12+12)..":"..(tonumber(m) or "00"); end);
		local start_hour, start_minute = range:match("(%d+):(%d+) *%-");
		local end_hour, end_minute = range:match("%- *(%d+):(%d+)");
		local op = tonumber(start_hour) > tonumber(end_hour) and " or " or " and ";
		if start_hour and end_hour then
			table.insert(clause, current_time_check(">", start_hour, start_minute));
			table.insert(clause, current_time_check("<", end_hour, end_minute));
		end
		if #clause == 0 then
			error("Unable to parse time range: "..range);
		end
		table.insert(conditions, "("..table.concat(clause, " "..op.." ")..")");
	end
	return table.concat(conditions, " or "), { "time:hour,min" };
end

function condition_handlers.LIMIT(spec)
	local name, param = spec:match("^(%w+) on (.+)$");
	local meta_deps = {};

	if not name then
		name = spec:match("^%w+$");
		if not name then
			error("Unable to parse LIMIT specification");
		end
	else
		param = meta(("%q"):format(param), meta_deps);
	end

	if not param then
		return ("not global_throttle_%s:poll(1)"):format(name), { "globalthrottle:"..name, unpack(meta_deps) };
	end
	return ("not multi_throttle_%s:poll_on(%s, 1)"):format(name, param), { "multithrottle:"..name, unpack(meta_deps) };
end

function condition_handlers.ORIGIN_MARKED(name_and_time)
	local name, time = name_and_time:match("^%s*([%w_]+)%s+%(([^)]+)s%)%s*$");
	if not name then
		name = name_and_time:match("^%s*([%w_]+)%s*$");
	end
	if not name then
		error("Error parsing mark name, see documentation for usage examples");
	end
	if time then
		return ("(current_timestamp - (session.firewall_marked_%s or 0)) < %d"):format(idsafe(name), tonumber(time)), { "timestamp" };
	end
	return ("not not session.firewall_marked_"..idsafe(name));
end

function condition_handlers.USER_MARKED(name_and_time)
	local name, time = name_and_time:match("^%s*([%w_]+)%s+%(([^)]+)s%)%s*$");
	if not name then
		name = name_and_time:match("^%s*([%w_]+)%s*$");
	end
	if not name then
		error("Error parsing mark name, see documentation for usage examples");
	end
	if time then
		return ("(current_timestamp - (session.firewall_marks and session.firewall_marks.%s or 0)) < %d"):format(idsafe(name), tonumber(time)), { "timestamp" };
	end
	return ("not not (session.firewall_marks and session.firewall_marks."..idsafe(name)..")");
end

function condition_handlers.SENT_DIRECTED_PRESENCE_TO_SENDER()
	return "not not (session.directed and session.directed[from])", { "from" };
end

-- TO FULL JID?
function condition_handlers.TO_FULL_JID()
	return "not not full_sessions[to]", { "to", "full_sessions" };
end

-- CHECK LIST: spammers contains $<@from>
function condition_handlers.CHECK_LIST(list_condition)
	local list_name, expr = list_condition:match("(%S+) contains (.+)$");
	if not (list_name and expr) then
		error("Error parsing list check, syntax: LISTNAME contains EXPRESSION");
	end
	local meta_deps = {};
	expr = meta(("%q"):format(expr), meta_deps);
	return ("list_%s:contains(%s) == true"):format(list_name, expr), { "list:"..list_name, unpack(meta_deps) };
end

-- SCAN: body for word in badwords
function condition_handlers.SCAN(scan_expression)
	local search_name, pattern_name, list_name = scan_expression:match("(%S+) for (%S+) in (%S+)$");
	if not (search_name) then
		error("Error parsing SCAN expression, syntax: SEARCH for PATTERN in LIST");
	end
	return ("scan_list(list_%s, %s)"):format(list_name, "tokens_"..search_name.."_"..pattern_name), { "scan_list", "tokens:"..search_name.."-"..pattern_name, "list:"..list_name };
end

-- COUNT: lines in body < 10
local valid_comp_ops = { [">"] = ">", ["<"] = "<", ["="] = "==", ["=="] = "==", ["<="] = "<=", [">="] = ">=" };
function condition_handlers.COUNT(count_expression)
	local pattern_name, search_name, comparator_expression = count_expression:match("(%S+) in (%S+) (.+)$");
	if not (pattern_name) then
		error("Error parsing COUNT expression, syntax: PATTERN in SEARCH COMPARATOR");
	end
	local value;
	comparator_expression = comparator_expression:gsub("%d+", function (value_string)
		value = tonumber(value_string);
		return "";
	end);
	if not value then
		error("Error parsing COUNT expression, expected value");
	end
	local comp_op = comparator_expression:gsub("%s+", "");
	assert(valid_comp_ops[comp_op], "Error parsing COUNT expression, unknown comparison operator: "..comp_op);
	return ("it_count(search_%s:gmatch(pattern_%s)) %s %d"):format(search_name, pattern_name, comp_op, value), { "it_count", "search:"..search_name, "pattern:"..pattern_name };
end

return condition_handlers;