Hi,
I'm having some issues wih resolving of the loopback ip address with
glibc's gethostbyaddr() / getnameinfo().
I have a setup with the following (abbreviated) /etc/hosts file:
==8<================
::1 ip6-localhost
127.0.0.1 localhost
==8<================
When using gethostbyaddr() or getnameinfo() to resolve ip address
127.0.0.1, the hostname "ip6-localhost" is returned, but I expected to
see "localhost".
When editing /etc/hosts and putting the 127.0.0.1 above the ::1 line,
things work normally.
It seems that glibc treats the loopback ip addresses (127.0.0.1 and ::1)
as a special case, and returns the first entry from the hosts file for
any loopback address, making no difference between ipv4 and ipv6. I
would expect libc to differ between the 2 addresses, but it seems it
doesn't.
However: I find no documentation in man pages or google saying that the
loopback addresses receive a special treatment, or that the entries in
the hosts file should be in some special order to make things work as
expected.
I can easily reproduce this on several gentoo hosts, running
glibc-2.10.1-r1 or glibc-2.9_p20081201-r2, and also on ubuntu 9.04
(libc6 version 2.9-4ubuntu6) and 9.10 (2.10.1-0ubuntu15).
Could someone explain to me if this is intended behaviour, and why, as I
tend to see this more as a bug?
--
Regards,
Tom
PS: I tested this by using the name-addr-test utils provided by postfix
(2.6.5 tarball, auxiliary/name-addr-test/ dir), because postfix was the
application that showed me this strange behaviour and the test utils
were readily available.
PS2: When you want to reproduce this, no actual ipv6 connectivity is
needed. Since glibc supports ipv6 out of the box, this should 'work'
with any setup.
