Re: -6 and mass_dns and dns.lua

[David Fifield <david () bamsoftware com>]

On Fri, Oct 31, 2008 at 01:45:17AM +0000, jah wrote:
> On 30/10/2008 22:44, David Fifield wrote:
> > I think I understand now. We can factor out the code that gets a list of
> > servers, but we should return an empty list if --system-dns is used.
> >
> > Does the attached patch work for you? I've tested that continues to use
> > system DNS for IPv6 lookups, and that get_dns_servers returns a list of
> > servers even with -6 except when --system-dns is also present. I haven't
> > tested it with ASN.nse.
> >
> > The patch builds on a few refactoring commits I made that didn't change
> > any outward behavior. The main change is moving the decision of whether
> > to run mass_dns from NmapOps.cc to nmap_dns.cc. As you noted, having -6
> > control o.mass_dns created a tricky bit of ambiguity.
>
> It only works for -6 when -n is specified because if we've already done
> an rdns lookup and we don't have a list of dns servers when
> get_dns_servers() is called at script scanning time then this test fails:
>     if(servs.size() == 0 && firstrun) {...}
>
> Also, some debugging output is incorrectly selected when -6 scans do
> rdns lookups and it prints out info meant for mass_dns resolving rather
> than system resolving:

Thanks for the testing and the good analysis. Can you give this new
patch a try? It uses the idea from your patch, but I put the static
variable inside init_servs rather than get_dns_servers, so that it is
initialized only once between nmap_mass_rdns_core and get_dns_servers.

David Fifield

Attachment: ipv6-dns-list-2.diff
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