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.
-- Mock util.time
local now = 0; -- wibbly-wobbly... timey-wimey... stuff
local function later(n)
now = now + n; -- time passes at a different rate
end
package.loaded["util.time"] = {
now = function() return now; end
}
local throttle = require "util.throttle";
describe("util.throttle", function()
describe("#create()", function()
it("should be created with correct values", function()
now = 5;
local a = throttle.create(3, 10);
assert.same(a, { balance = 3, max = 3, rate = 0.3, t = 5 });
local a = throttle.create(3, 5);
assert.same(a, { balance = 3, max = 3, rate = 0.6, t = 5 });
local a = throttle.create(1, 1);
assert.same(a, { balance = 1, max = 1, rate = 1, t = 5 });
local a = throttle.create(10, 10);
assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 });
local a = throttle.create(10, 1);
assert.same(a, { balance = 10, max = 10, rate = 10, t = 5 });
end);
end);
describe("#update()", function()
it("does nothing when no time has passed, even if balance is not full", function()
now = 5;
local a = throttle.create(10, 10);
for i=1,5 do
a:update();
assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 });
end
a.balance = 0;
for i=1,5 do
a:update();
assert.same(a, { balance = 0, max = 10, rate = 1, t = 5 });
end
end);
it("updates only time when time passes but balance is full", function()
now = 5;
local a = throttle.create(10, 10);
for i=1,5 do
later(5);
a:update();
assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 + i*5 });
end
end);
it("updates balance when balance has room to grow as time passes", function()
now = 5;
local a = throttle.create(10, 10);
a.balance = 0;
assert.same(a, { balance = 0, max = 10, rate = 1, t = 5 });
later(1);
a:update();
assert.same(a, { balance = 1, max = 10, rate = 1, t = 6 });
later(3);
a:update();
assert.same(a, { balance = 4, max = 10, rate = 1, t = 9 });
later(10);
a:update();
assert.same(a, { balance = 10, max = 10, rate = 1, t = 19 });
end);
it("handles 10 x 0.1s updates the same as 1 x 1s update ", function()
now = 5;
local a = throttle.create(1, 1);
a.balance = 0;
later(1);
a:update();
assert.same(a, { balance = 1, max = 1, rate = 1, t = now });
a.balance = 0;
for i=1,10 do
later(0.1);
a:update();
end
assert(math.abs(a.balance - 1) < 0.0001); -- incremental updates cause rouding errors
end);
end);
-- describe("po")
describe("#poll()", function()
it("should only allow successful polls until cost is hit", function()
now = 5;
local a = throttle.create(3, 10);
assert.same(a, { balance = 3, max = 3, rate = 0.3, t = 5 });
assert.is_true(a:poll(1)); -- 3 -> 2
assert.same(a, { balance = 2, max = 3, rate = 0.3, t = 5 });
assert.is_true(a:poll(2)); -- 2 -> 1
assert.same(a, { balance = 0, max = 3, rate = 0.3, t = 5 });
assert.is_false(a:poll(1)); -- MEEP, out of credits!
assert.is_false(a:poll(1)); -- MEEP, out of credits!
assert.same(a, { balance = 0, max = 3, rate = 0.3, t = 5 });
end);
it("should not allow polls more than the cost", function()
now = 0;
local a = throttle.create(10, 10);
assert.same(a, { balance = 10, max = 10, rate = 1, t = 0 });
assert.is_false(a:poll(11));
assert.same(a, { balance = 10, max = 10, rate = 1, t = 0 });
assert.is_true(a:poll(6));
assert.same(a, { balance = 4, max = 10, rate = 1, t = 0 });
assert.is_false(a:poll(5));
assert.same(a, { balance = 4, max = 10, rate = 1, t = 0 });
-- fractional
assert.is_true(a:poll(3.5));
assert.same(a, { balance = 0.5, max = 10, rate = 1, t = 0 });
assert.is_true(a:poll(0.25));
assert.same(a, { balance = 0.25, max = 10, rate = 1, t = 0 });
assert.is_false(a:poll(0.3));
assert.same(a, { balance = 0.25, max = 10, rate = 1, t = 0 });
assert.is_true(a:poll(0.25));
assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
assert.is_false(a:poll(0.1));
assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
assert.is_true(a:poll(0));
assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
end);
end);
end);