HTTP2 client doesn't handle multiple cookie values correctly

[peterhirn]

Bug Description

[RFC9113], Section 8.2.3

The Cookie header field [COOKIE] uses a semicolon (";") to delimit cookie-pairs (or "crumbs").

Currently the implementation has no special case for the cookie header and uses commas (",") as delimiter.

Using semicolon as delimiter should be an easy fix, otoh the linked RFC section continues:

To allow for better compression efficiency, the Cookie header field MAY be split into separate header fields, each with one or more cookie-pairs.

So maybe instead of

cookie: a=b; c=d; e=f

undici should send

cookie: a=b
cookie: c=d
cookie: e=f

🤔

Reproducible By

import http2 from "node:http2";
import { H2CClient } from "undici";

const port = process.env.PORT ?? 3001;

http2
  .createServer((req, res) => {
    console.log(req.headers);
    res.end();
  })
  .listen(port, async () => {
    const headers = { cookie: ["a=b", "c=d", "e=f"] };
    const client = new H2CClient(`http://localhost:${port}`);
    await client.request({ path: "/", method: "GET", headers });
  });

[Object: null prototype] {
  ':authority': 'localhost:3001',
  ':method': 'GET',
  ':path': '/',
  ':scheme': 'https',
  cookie: 'a=b, c=d, e=f',
  Symbol(sensitiveHeaders): [ 'cookie' ]
}

[metcoder95]

It sadly doesn't seems possible given the node:http2 implementation, nevertheless opened #4453 to address the issue