Drakma hides non-conforming HTTP 204 with content from the user

[phoe]

https://datatracker.ietf.org/doc/html/rfc7231#section-6.3.5

drakma/request.lisp

Lines 888 to 893 in 18b6ace

	((not (or (eq method :head)
	(= status-code 204)))
	(let (trailers)
	(multiple-value-setq (body trailers)
	(read-body http-stream headers external-format-body
	:decode-content decode-content))

I was bitten by it when our server sent a malformed HTTP 204 containing a body (see edicl/hunchentoot#247). Drakma (used in our tests) nonetheless reported the body as NIL, therefore causing a test to wrongly succeed. A workaround was to :want-stream t and then read from it ourselves.

Should this be a WONTFIX (the response is technically non-conforming), or is this something that should be changed?

[hanshuebner]

I've not gone deep into analyzing this, but if we can detect the presence of a body, we should rather throw an error if a body is unexpectedly presented.

[phoe]

That would also work. I can submit a PR that does this, preferably with some test case.

[stassats]

An error is probably not useful. What if you can't do anything about the response and want the body.

[phoe]

Sounds like a cerror to me, or a non-NIL body returned from HTTP 204. Non-conforming, yes, but the most useful too.

[stassats]

what does curl do

[phoe]

$ curl -vv -d '...' -X POST http://localhost:8080/login
Note: Unnecessary use of -X or --request, POST is already inferred.
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST /login HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.88.1
> Accept: */*
> Content-Length: 64
> Content-Type: application/x-www-form-urlencoded
> 
< HTTP/1.1 204 No Content
< Content-Length: 10
< Date: Fri, 27 Feb 2026 15:54:09 GMT
< Server: Hunchentoot 1.3.1
< Accept: */*
< Content-Type: text/html; charset=utf-8
< 
* Excess found: excess = 10 url = /login (zero-length body)
* Connection #0 to host localhost left intact

Seems like no body is printed or attempted to be read, but a warning is printed.

[phoe]

There's also Content-Length that is nonzero in that request (signifying that it's malformed). Drakma could warn in that case and then return a non-NIL body.

[phoe]

I plan on making it configurable with the same set of parameters as in edicl/hunchentoot#248, with :warn also being the default. That will cause Drakma to start warning and returning non-NIL content bodies on these malformed HTTP 204 responses, which is a possibly incompatible change.

Does that sound OK?