[dns-operations] [EXT] Re: systemd resolved ignores specified root

[Peter van Dijk]

On Fri, 2020-09-18 at 01:36 +0100, Tony Finch wrote:
> Dave Lawrence <tale at dd.org> wrote:
> > On this point, it just has no idea whether the original input that
> > started off the lookup had the trailing dot.
> 
> I don't think that's true: the interface between glibc and
> systemd-resolved uses a special NSS module and a D-Bus interface, not the
> DNS protocol. If I understand the docs correctly, the name sent over D-Bus
> is what the user typed without even IDNA conversion.
> 
> https://www.freedesktop.org/software/systemd/man/nss-resolve.html
> https://www.freedesktop.org/wiki/Software/systemd/resolved/
> 
> (reminds me of lwresd...)

I did not feel like reading docs so instead I made two straces
yesterday ('ping horse' and 'ping horse.')

ping.strace:24505 sendmsg(5, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="l\1\2\1
\0\0\0\2\0\0\0\242\0\0\0\1\1o\0\31\0\0\0/org/fre"..., iov_len=184},
{iov_base="\0\0\0\0\5\0\0\0horse\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
, iov_len=32}], msg_iovlen=2, msg_controllen=0, msg_flags=0},
MSG_DONTWAIT|MSG_NOSIGNAL) = 216
ping2.strace:24569 sendmsg(5, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="l\1\2\1
\0\0\0\2\0\0\0\242\0\0\0\1\1o\0\31\0\0\0/org/fre"..., iov_len=184},
{iov_base="\0\0\0\0\6\0\0\0horse.\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
iov_len=32}], msg_iovlen=2, msg_controllen=0, msg_flags=0},
MSG_DONTWAIT|MSG_NOSIGNAL) = 216

Indeed, the trailing dot makes it into /run/dbus/system_bus_socket.

Kind regards,
-- 
Peter van Dijk
PowerDNS.COM BV - https://www.powerdns.com/