The access log took $body_bytes_sent from res.body, which stays empty
for a static file because it is sent by a content provider. Every file
was logged as 0 bytes. Use the Content-Length of the response instead,
and 0 for HEAD.
req.path is percent-decoded, so a request like GET /%0D%0A... put a
literal CR/LF into the NGINX-style log lines and let a client forge
extra entries. Log the raw req.target (matching NGINX's $request) and
escape '"', '\', control and non-ASCII bytes as \xHH the way NGINX
does. Also note in the README logging section that req.path may
contain control characters and should be escaped before logging.
