commit f04938e02551c56a0363fca50d49fe97b0c9098f
author Ryo Ogawa <negibokken@gmail.com> Thu Feb 03 03:41:27 2022
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Feb 03 03:41:27 2022
tree 1d576390adf288a2fc16cf6733935faaa85fbddb
parent 82b0d78ea9e52e234484ccad4a22a65e1344fdb1

Fix parsing algorithm for Access Control Expose Headers (ACEH)

This CL fixes the implementation for parsing ACEH values to pass the two
failed WPT.

```
{
  "input": "Access-Control-Expose-Headers:\r\nAccess-Control-Expose-Headers: bb-8",
  "exposed": true
},
{
  "input": "Access-Control-Expose-Headers: ,bb-8",
  "exposed": true
},
```

According to the Fetch Standard [1], the first test case is interpreted
as below and it's the same as the second test case.

```
Access-Control-Expose-Headers: ,bb-8",
```

The Fetch Standard says the parsing ACEH algorithm follows the RFC 7230
[2].  And in RFC 7230, the empty element must be accepted and ignored
for legacy list rules [3].

> For compatibility with legacy list rules, a recipient MUST parse and
> ignore a reasonable number of empty list elements

[1] https://fetch.spec.whatwg.org/#example-header-list-get-decode-split
[2] https://fetch.spec.whatwg.org/#concept-response-cors-exposed-header-name-list
[3] https://datatracker.ietf.org/doc/html/rfc7230#section-7

Bug: 978146
Change-Id: Ic7a379c4bb0189299d0d64156173c3cc02a80323
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3422206
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/main@{#966572}