by davidben@chromium.org:

This is a minor feature request. It would be nice if http.Handler exposed the underlying
net.Conn for consumers to query state from. It does expose the tls.ConnectionState, but
if you're using a custom net.Listener implementation, there doesn't seem to be a way to
correlate calls to the Handler with the net.Conn the net.Listener returned.

My particular use case is pointing the standard HTTP server at a fork of crypto/tls to
write demo servers for testing how clients respond to this or that broken server
behavior, where the HTTP server prints out TLS connection state. Since it's a fork of
crypto/tls with quirks patched in, http.Request.TLS isn't filled in. Writing a dummy
HTTP/1.0 server is easy enough, and there's also http.Hijacker, but it'd be nice to be
able to use the existing HTTP server implementation without having to either reimplement
the HTTP stack or hijack the socket and lose the standard socket reuse, etc., behavior.