Use cache validation in serving of files

[Spixmaster]

I have an HTTP server which among other things serves static files via server->set_mount_point(constant::endpoint::mount_point, constant::directory::shared());.

If I understand correctly, Server::handle_file_request() is responsible for serving files from the mount point. I do not see validation mechanisms like Last-Modified or ETag which would save bandwidth with the only little downside of calculating an identifier like a hash.

There is a tendency that ETag is preferred over Last-Modified.

Good resources:

• https://http.dev/caching
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/ETag
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/If-None-Match
• https://www.rfc-editor.org/rfc/rfc9110.html#name-304-not-modified