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 json = require "util.json";
describe("util.json", function()
describe("#encode()", function()
it("should work", function()
local function test(f, j, e)
if e then
assert.are.equal(f(j), e);
end
assert.are.equal(f(j), f(json.decode(f(j))));
end
test(json.encode, json.null, "null")
test(json.encode, {}, "{}")
test(json.encode, {a=1});
test(json.encode, {a={1,2,3}});
test(json.encode, {1}, "[1]");
end);
end);
describe("#decode()", function()
it("should work", function()
local empty_array = json.decode("[]");
assert.are.equal(type(empty_array), "table");
assert.are.equal(#empty_array, 0);
assert.are.equal(next(empty_array), nil);
end);
end);
describe("testcases", function()
local valid_data = {};
local invalid_data = {};
local skip = "fail1.json fail9.json fail18.json fail15.json fail13.json fail25.json fail26.json fail27.json fail28.json fail17.json pass1.json";
setup(function()
local lfs = require "lfs";
local path = "spec/json";
for name in lfs.dir(path) do
if name:match("%.json$") then
local f = assert(io.open(path.."/"..name));
local content = assert(f:read("*a"));
assert(f:close());
if skip:find(name) then --luacheck: ignore 542
-- Skip
elseif name:match("^pass") then
valid_data[name] = content;
elseif name:match("^fail") then
invalid_data[name] = content;
end
end
end
end)
it("should pass valid testcases", function()
for name, content in pairs(valid_data) do
local parsed, err = json.decode(content);
assert(parsed, name..": "..tostring(err));
end
end);
it("should fail invalid testcases", function()
for name, content in pairs(invalid_data) do
local parsed, err = json.decode(content);
assert(not parsed, name..": "..tostring(err));
end
end);
end)
end);