Okay, I finally have actual code to share. This is the original
experimental pre_protocol_switch hook that Stefan and I were talking
about a while ago [1], rebased onto 2.4.18. The two patches are available at
https://github.com/jchampio/httpd/commits/dev/websocket-protocols
It is *not* an implementation of Stefan's most recent pseudocode (a
primary difference is that his proposal does the filter + upgrade in one
hook instead of two), and it doesn't solve many of the use cases that
you've already agreed must be handled:
- 100-continue is not handled correctly
- the incoming request body is not correctly dealt with
- there is only one switch point, at the handler stage
- etc.
*But* it is a working implementation from mod_websocket's point of view,
so I offer it up primarily for informational purposes. The module making
use of the new hook is available at
https://github.com/jchampio/apache-websocket/blob/dev/hook/mod_websocket.c
You might be most interested in the mod_websocket_pre_protocol_switch()
implementation (line 1627), which contains the pre-upgrade checks I need
to do to remain compliant with RFC 6455.
== Asides ==
1) The current Protocols API does not correctly ignore upgrades from
HTTP/1.0 requests; the latest commit to my experimental branch patched this.
2) As Stefan and I discussed in [1], Upgrade header values are
case-sensitive (correct?), but the RFC 6455 declares that servers should
respond to any protocol that's a case-insensitive match for "websocket".
To make matters worse, the official IANA upgrade token is "WebSocket",
but the RFC uses "websocket" throughout. I have seen both used in the
wild (Autobahn uses WebSocket; Firefox uses websocket), and I'm not sure
what the right way to resolve this is.
Hope this helps. Again, I don't expect this to actually be part of the
final solution, but sometimes it's nice to see code.
--Jacob
[1]
https://mail-archives.apache.org/mod_mbox/httpd-dev/201509.mbox/%3c55ff85f0.8040...@gmail.com%3E
