Sends a file to the given HTTP server response object.
When serving a file, certain request headers are supported to avoid sending
the file if the client has it already cached. These headers are
"If-None-Match". The client will be delivered
with the necessary
"Etag" (generated from the path, size and last
modification time of the file) and
Finally, HEAD requests will automatically be handled without reading the actual file contents. Am empty response body is written instead.
|req||The incoming HTTP request - cache and modification headers of the request can influence the generated response.|
|res||The response object to write to.|
|settings||Optional settings object enabling customization of how the file gets served.|