[Freeipa-devel] [PATCH] ipv6 compatible way to check the hostname

[Simo Sorce]

On Fri, 2008-03-28 at 17:34 -0400, Rob Crittenden wrote:
> Simo Sorce wrote:
> > Rob Crittenden wrote:
> >> Simo Sorce wrote:
> >>> This change checks the machine can resolve address using nsswitch 
> >>> host name resolution, this means we are also checking that /etc/hosts 
> >>> is not broken.
> >>>
> >>> It uses IPv6 aware system functions, so this should make it also IPv6 
> >>> compatible.
> >>>
> >>> It does not force to have a DNS set up correctly, but that's 
> >>> intentional as we might want to install DNS as part of the 
> >>> installation (--setup-bind) and checking DNS before installing it 
> >>> wouldn't really work :-)
> >>>
> >>> It still do try to check the DNS but currently it just exists 
> >>> silently if DNS is not configured. I am not sure how to raise a 
> >>> warning without throwing an exception that would make the install 
> >>> script abort in this case.
> >>>
> >>> It does error out if DNS is setup incorrectly.
> >>>
> >>
> >> +
> >> +    rev = None
> >> +    for rsn in rs:
> >> +        if rsn.dns_type == dnsclient.DNS_T_A:
> >> +            rev = rsn
> >> +            break
> >> +
> >> +    if rev == None:
> >> +        raise RuntimeError("Cannot find PTR record for %s" % addr)
> >> +
> >> +    reverse = rev.rdata.ptrdname
> >>
> >> Should you be looking for DNS_T_PTR here instead? If you have an A 
> >> record you won't have a ptrdname.
> >>
> >> You need to add a try/except around socket.getaddrinfo() to catch 
> >> errors if the hostname isn't found so a more useful error message can 
> >> be returned than 'Name or service not known'
> >>
> >> gethostbyaddr may need a try/except around it too.
> >>
> >> rob
> >>
> > 
> > 
> > 
> > Good points, new patch attached.
> 
> I have just a couple more comments (sorry, should have included these in 
> the first patch):
> 
> - We should say why 127.0.0.1/::1 is an Invalid IP address. Or rather, 
> just say that the hostname needs to resolve to a real address or something.
> - When are you planning on filling in the #TODO raise a warning? What 
> happens if the hostname is a CNAME, will it work? It kinda looks like it 
> will still be accepted.

Good points again, newer patch attached.
 
-- 
Simo Sorce * Red Hat, Inc * New York
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