How to do an early stop?

[Kludex]

Hi there 👋

I'm trying to implement a flag --limit-request-header-count on uvicorn, which I implemented changing the value of an attribute too_many_headers and raising an exception from on_header callback, see https://github.com/encode/uvicorn/pull/1683/files.

My question is: is my implementation as intended? Should the HttpParserCallbackError send more information when an exception happens from one of the callbacks?

[Kludex]

It looks like checking the count doesn't make much sense if we can limit the size of the headers. How can I do it for httptools? Should it be on httptools itself?

[Kludex]

Ok. Now I understand more. What I did doesn't make any sense.

httptools does something cool here:

httptools/httptools/parser/parser.pyx

Lines 166 to 183 in e2d1a46

	if PyMemoryView_Check(data):
	buf = PyMemoryView_GET_BUFFER(data)
	data_len = <size_t>buf.len
	err = cparser.llhttp_execute(
	self._cparser,
	<char*>buf.buf,
	data_len)
	else:
	buf = &self.py_buf
	PyObject_GetBuffer(data, buf, PyBUF_SIMPLE)
	owning_buf = True
	data_len = <size_t>buf.len
	err = cparser.llhttp_execute(
	self._cparser,
	<char*>buf.buf,
	data_len)

Still, I cannot do anything on uvicorn to limit the size of the headers/body, because I need to do it before it's parsed.

Ref.: https://github.com/nodejs/node/tree/fd36a8dadba7fcbd74f0ab82a8ee1b3150ce5167/deps/llhttp/src (this is for myself)