[RFC] hostnamed

[Thiago Macieira]

On Tuesday, 19 de April de 2011 20:17:40 Lennart Poettering wrote:
> >  - between 1 and 64 characters
> >  - contains letters A-Z a-z, digits 0-9 and the hyphen (dash)
> >  - does not start or end in a dash
> > 
> > That would mean ... is not a valid hostname, nor -.-.
> 
> With these rules "..." would still be a valid hostname.

The labels between those dots have size 0, so they don't validate.

> If it was for me I would mandate that the hostname cannot include ".",
> i.e needs to be a single DNS label. However I know that people disagree
> with that, and some folks think DNS FQDN is the way to go, and they have
> a bit of point in that.

Well, the FQDN must exist.

> > In time: you may want to declare that the international hostnames that
> > hostnamed deals with are ACE encoded as per RFC 3490. That means if my
> > 
> > machine's hostname is:
> > 	thiago.josé.macieira.example.org
> > 
> > hostnamed should be given and will return instead:
> > 	thiago.xn--jos-dma.macieira.example.org
> 
> mDNS and DNS differ on this. The former says i18n is done via UTF-8, and
> the latter says via that xn-- notation. gethostname() should probably
> return something that is useful on mDNS, on DNS-SD, on LDAP and maybe
> even for YP/NIS alike. Hence hostnamed is strict here.

mDNS is broken. The UTF-8 encoding causes a mixed case sensitiveness problem 
because DNS is case insensitive for ASCII, but case sensitive for everything 
else.

The ACE encoding of IDNA solves this problem neatly by requiring that 
hostnames be nameprepped instead (it solves the problem by removing the 
problem). The hostname and the pretty name are not related in this case and it 
seems to be that in your design the same also holds true.

> I think the "pretty hostname" is the right place to use non-7bit-ASCII
> chars, and spaces and things. Having the non-preety hostnames with
> stricter rules is a good thing I believe.

Agreed.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 190 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.freedesktop.org/archives/xdg/attachments/20110419/872d917c/attachment.pgp>