Check for OCSP status was missed in 581cf2267, resulting
in a broken validation.

Reported by Mufeed VH of Winfunc Research.

Previously, it was not properly cleared retaining length as part of
authenticating with CRAM-MD5 and APOP methods that expect to receive
password in auth response.  This resulted in null pointer dereference
and worker process crash in subsequent auth attempts with CRAM-MD5.

Reported by Arkadi Vainbrand.

Now host name resolved from client address is validated to only contain
the characters specified in RFC 1034, Section 3.5.  The validation allows
to avoid injections when using the resolved host name in auth_http and
smtp proxy.

Reported by Asim Viladi Oglu Manizada, Colin Warren,
Xiao Liu (Yunnan University), Yuan Tan (UC Riverside), and
Bird Liu (Lanzhou University).

Previously, when alias was used in a location with Dav COPY or MOVE
enabled, and the destination URI was shorter than the alias, integer
underflow could happen in ngx_http_map_uri_to_path(), which could
result in heap buffer overwrite, followed by a possible segfault.
With some implementations of memcpy(), the segfault could be avoided
and the overwrite could result in a change of the source or destination
file names to be outside of the location root.

Reported by Calif.io in collaboration with Claude and Anthropic Research.

Previously, a 32-bit overflow could happen while validating atom entries
count.  This allowed processing of an invalid atom with entrires beyond
its boundaries with reads and writes outside of the allocated mp4 buffer.

Reported by Prabhav Srinath (sprabhav7).

Previously, data validation checks did not cover the cases when the output
contained empty buffers.  Such buffers are considered illegal and produce
"zero size buf in output" alerts.  The change rejects the mp4 files which
produce such alerts.

Also, the change fixes possible buffer overread and overwrite that could
happen while processing empty stco and co64 atoms, as reported by
Pavel Kohout (Aisle Research) and Tim Becker.

Updates the proxy module to use HTTP/1.1 as the default protocol when
communicating with upstream servers. This change unlocks features
such as persistent connections and chunked transfer encoding. Configurations
that require HTTP/1.0 can still override the protocol explicitly.

Keepalive is now automatically enabled in the "local" mode for upstreams
defined in configuration files. Cached keepalive connections are no longer
shared between different locations referencing the same explicit upstream
unless keepalive is explicitly configured without the "local" parameter.

To disable keepalive entirely, use keepalive 0; inside the upstream block.
To allow sharing cached connections between locations, configure
keepalive <max_cached>; without the "local" parameter.