This is required due to lack of a graceful shutdown: there is a small gap
between the runtime's memory pool release and router process's exit. Thus, a
worker thread may start processing a request between these two operations,
which may result in an http fields hash access and subsequent crash.
To simplify issue reproduction, it makes sense to add a 2 sec sleep before
exit() in nxt_runtime_exit().
This field was intended for MIME type lookup by file extension when serving
static files, but this use case is too narrow; only a fraction of requests
targets static content, and the URI presumably isn't rewritten. Moreover,
current implementation uses the entire filename for MIME type lookup if the
file has no extension.
Instead of extracting filenames and extensions when parsing requests, it's
easier to obtain them right before serving static content; this behavior is
already implemented. Thus, we can drop excessive logic from parser.
Earlier, the paths were normalized only if there was a "/" at the end, which
is wrong according to section 5.2.4 of RFC 3986 and hypothetically may allow
to the directory above the document root.
In theory, all space characters in request target must be encoded; however,
some clients may violate the specification. For the sake of interoperability,
Unit supports unencoded space characters.
Previously, if there was a space character before the extension or arguments
parts, those parts weren't recognized. Also, quoted symbols and complex
target weren't detected after a space character.
Allowing characters up to 0xFF doesn't conflict with RFC 7230.
Particularly, this make it possible to pass unencoded UTF-8 data
through HTTP headers, which can be useful.
The level hash uses the NULL value as the indicator of a free entry in a bucket.
So, inserting a NULL value breaks the hash and can lead to a bucket overflow.
In case of the collision counter, the value wasn't initialized, since it's not
needed for the purpose of checking collisions. As a result, it might contain
any garbage from the stack and in some rare cases the value was NULL.
Now the value is initilized.
