Don't return file content for HEAD requests in ServeFile, ServeDir

[jplatte]

As discussed in tokio-rs/axum#84, ServeFile and ServeDir could be improved re. handling of HEAD requests. Responses to HEAD requests should be identical to the corresponding GETs response, but without a body.

The implementation should probably use fs::metadata instead of opening the file to fulfill HEAD requests more efficiently.

[jplatte]

I wonder whether it makes sense to even support all methods by default. Just ignoring POST & PUT bodies and returning the file contents on TRACE / DELETE / OPTIONS seems kind of weird. This probably applies to other services in tower-http as well.

[davidpdrsn]

Fixing this will unfortunately be a breaking change since ServeFile implements Service for any type R rather than Service<Request<ReqBody>>.

[davidpdrsn]

I wonder whether it makes sense to even support all methods by default. Just ignoring POST & PUT bodies and returning the file contents on TRACE / DELETE / OPTIONS seems kind of weird. This probably applies to other services in tower-http as well.

I agree. Method handling could be improved for ServeDir and ServeFile. Off the top of my head I don't any other services have similar issues.

[jplatte]

Oh I see, there's only one more service currently which is the redirect one (which probably should work the same regardless of HTTP method).

[Nehliin]

#156 Have the same required breaking change since it needs to inspect the Accepted-Encoding headers so I could pick this up after that PR is reviewed