Breaking change: deprecate body on http methods with no defined body semantics

[pxue]

Extending discussion from #2305 (comment)

if there's no explicit body, or it is a method whose body's semantics are not defined, set content-length: 0

This will be a breaking change:

• All shouldSendContentLength=false methods will no longer parse and send any attached body
• content-length will be forced to 0 on request

[metcoder95]

To give more context around it:

The discussion was going around not allowing to attach bodies to those requests whose doesn't have defined semantics to handle the body of a given request (e.g. GET, OPTIONS, etc.).
Currently undici allows these cases, this issue was more to discuss wether we should allow it or now.

Having second thoughts about it

It might be good to keep it this way, as anyways it is up to the server to decide what to do in those scenarios.

Thoughts?

cc @mcollina @ronag @KhafraDev

[mcollina]

dispatch should allow it. fetch should follow the spec. I'm on the fence about request.

[metcoder95]

Over a quick search, it seems fetch spec does not say what to do exactly in these scenarios (unless I'm overlooking it), just specifies redirects. Although Chrome throws when attempting to.

For dispatch I agree, for request I think we can simplify our lives by just keeping it as is; the changes done by #2305 can be the kickoff and keep an eye on it.

[Ethan-Arrowood]

If Fetch spec isn't explicit, then try to copy Chrome and other browser's behavior.

[KhafraDev]

The fetch spec has very little to do with http (the rfcs are mentioned as reference points for implementations). We should instead follow either what the rfcs say or what's best for node.

[metcoder95]

Then the question remains open:

From what I've seen, both browsers (firefox and chrome) throw when attempting to pass a body on a GET request; we can follow their lead and do the same or keep it as is.

At much, I believe undici should remain untouched but maybe fetch aligns with browsers

[KhafraDev]

that part is from the fetch spec, which undici implements. I also think undici should stay the same. If anyone feels differently then this issue can be re-opened.

[Ethan-Arrowood]

Agreed - undici can do what it wants HTTP wise if things aren't specified. Fetch should strictly follow spec and browsers.