http.server does not accept "absolute-form" as "request-target"

[GreenYun]

Bug report

Bug description:

python3 -m http.server &
printf "GET http://127.0.0.1:8000/ HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n" | nc 127.0.0.1 8000

Expected: 200 OK
Got: 404 File not found

Reference:

[RFC 9112] (Section 3.2)
[RFC 7230] (Section 5.3)
[RFC 2616] (Section 5.1.2)

CPython versions tested on:

3.13

Operating systems tested on:

Linux

[donBarbos]

it seems this is expected behavior, since if the request ends with a backslash, a 404 error is returned:

cpython/Lib/http/server.py

Lines 771 to 778 in 5d8e432

	# check for trailing "/" which should return 404. See Issue17324
	# The test for this was added in test_httpserver.py
	# However, some OS platforms accept a trailingSlash as a filename
	# See discussion on python-dev and Issue34711 regarding
	# parsing and rejection of filenames with a trailing slash
	if path.endswith("/"):
	self.send_error(HTTPStatus.NOT_FOUND, "File not found")
	return None

this was discussed here: #78892

[donBarbos]

you can use next command:

printf "GET / HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n" | nc 127.0.0.1 8000

[GreenYun]

it seems this is expected behavior, since if the request ends with a backslash, a 404 error is returned:

This is not expected. A "request-target" with trailing backslash is for listing the contents for a real directory.

you can use next command:

printf "GET / HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n" | nc 127.0.0.1 8000

Yes, this is correct.

However, the question was found since, according to the RFCs, a forward HTTP proxy may forward the "request-target" to the origin server. This leads the real client to get an error when accessing via an HTTP proxy.

[donBarbos]

I understand you, and I'd be happy to fix this behavior if core developer agrees.

But I think it's worth noting that "absolute-form" is typically used when making a request through an HTTP proxy, and http.server isn't a proxy - it's a basic file-serving web server.

cc @picnixz

[GreenYun]

and http.server isn't a proxy - it's a basic file-serving web server.

When I found this problem, I was using http.server as the origin server behind a proxy server, and I got 404 because the proxy server forwarded the "absolute-form".