ValueError: unsupported protocol with HTTP/1.0 proxy server

[bgK]

When using websockets 15.0.1 to establish a connection through a HTTP/1.0 only proxy server, I get the following traceback:

venv/lib64/python3.11/site-packages/websockets/asyncio/client.py:765: in run_parser
    next(self.parser)
venv/lib64/python3.11/site-packages/websockets/http11.py:250: in parse
    raise ValueError(
E   ValueError: unsupported protocol; expected HTTP/1.1: HTTP/1.0 200 Connection Established

The above exception was the direct cause of the following exception:
tests/test_notification.py:31: in test_websocket
    async with websockets.connect(uri, origin = gateway_url, additional_headers = additional_headers, ssl = ssl_context, proxy = proxy) as websocket:
venv/lib64/python3.11/site-packages/websockets/asyncio/client.py:587: in __aenter__
    return await self
venv/lib64/python3.11/site-packages/websockets/asyncio/client.py:541: in __await_impl__
    self.connection = await self.create_connection()
venv/lib64/python3.11/site-packages/websockets/asyncio/client.py:440: in create_connection
    transport = await connect_http_proxy(
venv/lib64/python3.11/site-packages/websockets/asyncio/client.py:815: in connect_http_proxy
    await protocol.response
E   websockets.exceptions.InvalidProxyMessage: did not receive a valid HTTP response from proxy

Manually checking the behavior of the proxy server:

$ nc proxy-host.com 3128
CONNECT websocket-host.com:443 HTTP/1.1
Host: websocket-host.com

HTTP/1.0 200 Connection Established

It is my understanding reading the spec that responding with HTTP/1.0 to a HTTP/1.1 request is allowed.

[aaugustin]

This is a valid improvement request (although I didn't really want to become an expert in HTTP proxies when I started this library...)

Out of curiosity, in what environment are you hitting this problem? Do you know what proxy is being used?

[bgK]

Out of curiosity, in what environment are you hitting this problem? Do you know what proxy is being used?

The proxy server is very much out of my reach, but looks like McAfee Web Gateway / Skyhigh Secure Web Gateway.

[aaugustin]

OK - looks like a typical corporate environment - clearly in scope of what I wanted to support when I implemented support for HTTP proxies. I'll do something about it.

[aaugustin]

Hello, would you be able to confirm that #1618 fixes your problem, please?