Providing a request body when the response is 401 fails

[beanow-at-crabnebula]

Bug Description

What seems to be from a change in #4747

Any (non websocket) request that includes a request body and gets a 401 response errors.

    TypeError: fetch failed

      at Object.processResponse (node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:31323:21)
      at node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:31709:23

    Cause:
    expected non-null body source

      at makeNetworkError (node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:30097:36)
      at httpNetworkOrCacheFetch (node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:31924:20)
      at httpFetch (node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:31733:37)
      at mainFetch (node_modules/.pnpm/wrangler@4.75.0/node_modules/wrangler/wrangler-dist/cli.js:31495:24)

Reproducible By

https://github.com/beanow-at-crabnebula/undici-401-request-body

Additional context

The reproduction there uses Cloudflare worker's wrangler.
Which bundles undici@7.24.4.

[mcollina]

Can you please provide a reproduction that only uses undici?

[beanow-at-crabnebula]

I've attempted the following as a test/jest/issue-4910.js and that passes.

"use strict";

const { createServer } = require("node:http");
const { once } = require("node:events");
const { request } = require("../..");

it("response with a 401 is valid even when request has a body", async () => {
  const server = createServer({ joinDuplicateHeaders: true }, (req, res) => {
    res.statusCode = 401;
    res.end();
  }).listen(0);

  await once(server, "listening");

  const res = await request(`http://localhost:${server.address().port}`, {
    method: "POST",
    body: "Example body",
  });

  expect(res.statusCode).toBe(401);
  server.close();
});

That being said, it's an apples to oranges comparison.

1. Because WorkerD is not Node.js
2. Their fetch function clearly wraps the actual request call to undici somehow

So I'm uncertain whether there's still a way to invoke undici in such a way this causes the issue regardless of those differences.

[beanow-at-crabnebula]

There's a root-cause written up here cloudflare/workers-sdk#12967 (comment)
👏 @petebacondarwin

Would you be able to reproduce this in Nodejs as well?