On Mon, 2024-02-05 at 19:53 +0000, Chuck Lever III wrote: > > > > On Feb 5, 2024, at 11:17 AM, Trond Myklebust > > <trondmy@xxxxxxxxxxxxxxx> wrote: > > > > On Mon, 2024-02-05 at 15:13 +0000, Chuck Lever III wrote: > > > > > > > > > A DNS label is just a hostname (fully-qualified or not). It > > > never includes a port number. > > > > > > According to RFC 8881, fs_location4's server field can contain: > > > > > > - A DNS label (no port number; 2049 is assumed) > > > > > > - An IP presentation address (no port number; 2049 is assumed) > > > > > > - a universal address > > > > > > A universal address is an IP address plus a port number. > > > Therefore > > > a universal address is the only way an alternate port can be > > > communicated in an NFSv4 referral. > > > > That's not strictly true. RFC8881 has little to say about how you > > are > > to go about using the DNS hostname provided by fs_locations4. There > > is > > just some non-normative and vague language about using DNS to look > > up > > the addresses. > > > > The use of DNS service records do allow you to look up the full IP > > address and port number (i.e. the equivalent of a universal > > address) > > given a fully qualified hostname and a service. While we do not use > > the > > hostname that way in the Linux NFS client today, I see nothing in > > the > > spec that would appear to disallow it at some future time. > > We absolutely could do that. But first a service name would need to > be > reserved, yes? > > https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=dns > What's wrong with the one that is already assigned? I'm talking about: nfs 2049 tcp Network File System - Sun [Brent_Callaghan] [Brent_Callaghan] Defined TXT keys: path=<path to mount point> Microsystems nfs 2049 udp Network File System - Sun [Brent_Callaghan] [Brent_Callaghan] Defined TXT keys: path=<path to mount point> Microsystems nfs 2049 sctp Network File System [RFC5665] Defined TXT keys: path=<path to mount point> -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
