"A request body was provided when none was expected" with proxies that set transfer-encoding

[dbkr]

Describe the bug

When running a PDS behind some proxies (in this instance, a Cloudflare tunnel) any POST without a body fails with, "A request body was provided when none was expected". This is because the proxy sets a "Transfer-Encoding: Chunked" header even when no body is sent.

Arguably this is a bug in the proxy, but the getBodyPresence distinguishes between "no body" and "empty body" when the only thing that actually matters to the validator function is whether a body is present and non-zero length or absent/empty. The validateInput reads the body anyway, so it might be more robust to wait until after it reads the body and then just asserts that the body is present and non-zero length if one is expected and vice-versa.

I may be able to make a PR for this if welcome.

To Reproduce

Steps to reproduce the behavior:

1. Run a PDS instance behind a Cloudflare tunnel
2. Log in with a client and make a request with no body, eg. request an email confirmation token.
3. Observe that the request is rejected with the above error.

Expected behavior

The request succeeds as normal.

Details

• Operating system: Ubuntu 24.04.1 LTS
• Node version: 20.11.1 (official PDS docker image)

Additional context

A workaround to this particular failure is to disable chunked transfer encoding in the cloudflare tunnel options.