Test that clients read Upgrade and Connection headers as case-insensitive ASCII

[deanveloper]

Under section 4.1: https://datatracker.ietf.org/doc/html/rfc6455#section-4.1

   2.  If the response lacks an |Upgrade| header field or the |Upgrade|
       header field contains a value that is not an ASCII case-
       insensitive match for the value "websocket", the client MUST
       _Fail the WebSocket Connection_.

   3.  If the response lacks a |Connection| header field or the
       |Connection| header field doesn't contain a token that is an
       ASCII case-insensitive match for the value "Upgrade", the client
       MUST _Fail the WebSocket Connection_.

I made my own autobahn-compliant websocket client but it immediately failed because https://ws.discord.gg/ replies with "Connection: upgrade"

[deanveloper]

Autobahn also doesn't seem to test that clients do case-insensitive checks for header names

[oberstet]

just a few quick comments:

• related: Add "Connection: keep-alive, Upgrade" test case #82
• AutobahnPython WebSocket opening handshake / header parsing code is here: https://github.com/crossbario/autobahn-python/blob/7bc85b34e200640ab98a41cfddb38267f39bc92e/autobahn/websocket/protocol.py#L2592
• specifically, HTTP header parsing code (which is case insensitive according to spec) is here: https://github.com/crossbario/autobahn-python/blob/7bc85b34e200640ab98a41cfddb38267f39bc92e/autobahn/websocket/protocol.py#L255

Autobahn also doesn't seem to test that clients do case-insensitive checks for header names

it does: https://github.com/crossbario/autobahn-python/blob/7bc85b34e200640ab98a41cfddb38267f39bc92e/autobahn/websocket/protocol.py#L2697

now, of course this latter behavior is wrt to AutobahnPython (as a WebSocket client) - not the testsuite specifically testing for HTTP headers / opening handshake processing of the WebSocket library implementation.

rgd the latter, pls lets stick to the existing issue #82 ...