From 103e1ff08c00590be56c98aa5647e92c7fa78631 Mon Sep 17 00:00:00 2001

From: Mustafa Emre Acer <meacer@chromium.org>

Date: Fri, 18 Nov 2022 22:52:00 +0000

Subject: [PATCH] IDN Spoof Checks: Disallow ZWJ and ZWNJ in ICU versions below

 72

​

ICU 72 updates to Unicode 15 which changes the zero width joiner (ZWJ)

and zero width non-joiner (ZWNJ) characters from

Identifier_Status=Allowed to Identifier_Status=Restricted. These

characters are therefore no longer allowed by default in ICU 72.

​

crbug/694157 recently implemented Non-Transitional IDNA 2008 behind a

flag. ZWJ and ZWNJ are disallowed in Transitional Mode but allowed in

Non-Transitional Mode, so the test cases with the Non-Transitional Mode

enabled fail in ICU 72.

​

This CL removes ZWJ and ZWNJ from the allowed identifiers set for

ICU versions below 72. This effectively disables these characters even

in Non-Transitional Mode.

​

This is a temporary fix. Once ICU 72 is rolled out, we should check if

we can use UIDNA_CHECK_CONTEXTJ and explicitly add ZWJ and ZWNJ to

the allowed sets again.

​

Bug: 1386204, 694157

Change-Id: I606c43b9d94fea0f2331e5aed530f633bb94517c

Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4038542

Reviewed-by: Frank Tang <ftang@chromium.org>

Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>

Cr-Commit-Position: refs/heads/main@{#1073605}

---

 .../spoof_checks/idn_spoof_checker.cc         |  9 ++++++

 .../idn_spoof_checker_unittest.cc             | 28 +++++++++++--------

 2 files changed, 25 insertions(+), 12 deletions(-)

​

Index: chromium-110.0.5481.38/components/url_formatter/spoof_checks/idn_spoof_checker.cc

===================================================================

--- chromium-110.0.5481.38.orig/components/url_formatter/spoof_checks/idn_spoof_checker.cc

+++ chromium-110.0.5481.38/components/url_formatter/spoof_checks/idn_spoof_checker.cc

@@ -722,6 +722,15 @@ void IDNSpoofChecker::SetAllowedUnicodeS

   allowed_set.remove(0x200Du);  // Zero Width Joiner

 #endif

+#if U_ICU_VERSION_MAJOR_NUM < 72

+  // Unicode 15 changes ZWJ and ZWNJ from allowed to restricted. Restrict them

+  // in lower versions too. This only relevant in Non-Transitional Mode as

+  // Transitional Mode maps these characters out.

+  // TODO(crbug.com/1386204): Remove these after ICU 72 is rolled out.

+  allowed_set.remove(0x200Cu);  // Zero Width Non-Joiner

+  allowed_set.remove(0x200Du);  // Zero Width Joiner

+#endif

+

   uspoof_setAllowedUnicodeSet(checker_, &allowed_set, status);

 }

​