Bug#343140: libc6: resolver always checks search list in /etc/resolv.conf
Marco d'Itri wrote:
> On Dec 21, Gabor Gombas <gombasg@sztaki.hu> wrote:
>
>>It's not a bug. It may be inefficient, but that's not a bug in itself.
>
> I find this reasoning very peculiar. If an algorithm is inefficient and
> this causes problems then it is obviously buggy.
> And it's doubly buggy if its inefficiencies cause are harmful for
> third parties.
Just wanted to add some more information to this bug report.
Etch has the exact same behavior as sarge. I tested on a system running
the latest version of glibc from testing.
To add some perspective on this issue, I did the same test on a FreeBSD
6.0 system which has IPv6 support. Interestingly, it does the sane
thing and only does one extra lookup, e.g. the IPv6 query for the
initial hostname, regardless of how many search domains are listed.
Search lines in /etc/resolv.conf aren't referenced unless the hostname
contains less than one dot, which corresponds to the documentation. So
although it's tempting to write this off as an inherent flaw in IPv6
support, FreeBSD apparently got it right.
Please don't take my FreeBSD comparison as anything more than bug
insight. I prefer Debian to all other distros/BSDs and this bug does
not change that. But the performance implications of this bug are real,
especially when compared to competing solutions.
As I mentioned before, disabling ipv6 kernel support in
/etc/modprobe.d/aliases does not help.
Thanks.
Regards,
Ed
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