2012551 - Double Punycode prefix tests fail

Status: NEW

(Core :: Networking: DNS, defect, P3)

Description

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

According to https://wpt.fyi/results/url/IdnaTestV2.window.html?label=master&label=experimental&aligned&q=%2Furl%2FIdnaTestV2.window.html we are failing two tests that repeat the Punycode prefix.

We should investigate.

Comment 1

[Valentin Gosu [:valentin] {{ PTO 3 July - 3 August }}]

The failing tests are:

ToASCII("xn--xn--a--gua.pt") V4; V2 (ignored)
ToASCII("xn--xn---epa") V4; V2 (ignored)

I noticed those tests also fail in Servo.
Running the rust-url parser code, it seems it parses sucessfully.

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=89155180832066701aa70144738cb923

So the problem is probably in the IDNA crate, which we use in Firefox too.