The variable `conn->httpversion` was used for several purposes and it
was unclear at which time the value represents what.
- rename `conn->httpversion` to `conn->httpversion_seen`
This makes clear that the variable only records the last
HTTP version seen on the connection - if any. And that it
no longer is an indication of what version to use.
- Change Alt-Svc handling to no longer modify `conn->httpversion`
but set `data->state.httpwant` for influencing the HTTP version
to use on a transfer.
- Add `data->req.httpversion_sent` to have a record of what
HTTP version was sent in a request
- Add connection filter type CF_TYPE_HTTP
- Add filter query `CF_QUERY_HTTP_VERSION` to ask what HTTP
filter version is in place
- Lookup filters HTTP version instead of using `conn->httpversion`
Test test_12_05 now switches to HTTP/1.1 correctly and the
expectations have been fixed.
Removed the connection fitler "is_httpN()" checks and using
the version query instead.
Closes#16073
A connection that has seen an HTTP major version now refuses any other
major HTTP version in future responses. Previously, a HTTP/1.x
connection would just silently accept HTTP/2 or HTTP/3 in the status
lines as long as it had support for those built-in. It would then just
lead to confusion and badness.
Indirectly Spotted by CodeSonar which identified a duplicate assignment
in this function.
Add test 471 to verify
Closes#13421
