Date: Tue, 26 Oct 1999 09:17:40 +0000 From: Matthew Seaman <m.seaman@inpharmatica.co.uk> To: simon.hewison@demon.net Cc: freebsd-gnats-submit@FreeBSD.ORG, freebsd-bugs@FreeBSD.ORG Subject: Re: conf/14522: dhclient incorrectly reads and sets hostname as a hex string Message-ID: <381571B4.7C8E2B60@inpharmatica.co.uk> References: <19991025173454.F0C4B15194@hub.freebsd.org>
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simon.hewison@demon.net wrote:
>
> >Number: 14522
> >Category: conf
> >Synopsis: dhclient incorrectly reads and sets hostname as a hex string
> >Confidential: no
> >Severity: non-critical
> >Priority: low
> >Responsible: freebsd-bugs
> >State: open
> >Quarter:
> >Keywords:
> >Date-Required:
> >Class: sw-bug
> >Submitter-Id: current-users
> >Arrival-Date: Mon Oct 25 10:40:00 PDT 1999
> >Closed-Date:
> >Last-Modified:
> >Originator: Simon Hewison
> >Release: 3.3-RELEASE
> >Organization:
> Demon Internet
> >Environment:
> FreeBSD 67:77:2d:69:6e:64:65:78:2d:32:0 3.3-RELEASE FreeBSD 3.3-RELEASE #0: Thu Sep 16 23:40:35 GMT 1999 jkh@highwing.cdrom.com:/usr/src/sys/compile/GENERIC i386
> >Description:
> When using the standard dhcp client configuration, and when the DHCP server sets the hostname, dhclient sets the hostname to a colon separated hexadecimal representation of the string which is the hostname finished off with the null termination byte.
> >How-To-Repeat:
> Get a Microsoft DHCP server to assign a hostname to a reserved lease.
>
> >Fix:
> don't assign a hostname by dhcp, set it in /etc/rc.conf :-(
>
> >Release-Note:
> >Audit-Trail:
> >Unformatted:
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
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For what it's worth, here's a /etc/dhclient-enter-hooks script I kludged
together to get round this problem. Not pretty, not very well tested and just
one of those temporary fixes that seems to have settled in for the duration.
#!/bin/sh
# Local customizations for /sbin/dhclient-script Here we just setup
# the hostname. This is imported into /sbin/dhclient-script via
# `. /etc/dhclient-enter-hooks'
# Check on the various DHCP variables we would like to see. These are
# all independant of the particular interface we're managing, but as
# we only have one interface per machine, here will do as well as
# anywhere.
if [ x$new_host_name != x ]; then
# isc-dhcpd 2.0b1p26 supplies/expects the hostname as an arbitrary
# hex encoded binary string `xx:xx:xx' where x are hex digits..
# isc-dhcpd 2.0b1pl4 (which we're using as the server) supplies
# the hostname as an ascii string. Why the change? This kludge
# converts to ascii if necessary.
if echo $new_host_name | \
grep -Ex '([[:xdigit:]]{2}:)+[[:xdigit:]]{2}' >/dev/null 2>&1;
then
new_host_name=`perl -e 'map { print chr hex $_; } \
split /:/, $ARGV[0];' $new_host_name`
fi
$LOGGER "New Host Name: $new_host_name"
fi
if [ x$old_host_name != x ]; then
# Need to decode old_host_name in the same way (?)
if echo $old_host_name | \
grep -Ex '([[:xdigit:]]{2}:)+[[:xdigit:]]{2}' >/dev/null 2>&1;
then
old_host_name=`perl -e 'map { print chr hex $_; } \
split /:/, $ARGV[0];' $old_host_name`
fi
fi
# Define functions to substitute DHCP data into local config files
# or to set/change various system attributes. Nb. this relies on
# overwriting the static values set from rc.* files on boot-up.
set_host_name() {
if [ x$new_host_name != x ] \
&& [ x$new_host_name != x$old_host_name ]
then
hostname $new_host_name
fi
$LOGGER set hostname to $new_host_name
}
# Test $reason to discover why we were called and amend our
# configuration appropriately.
exit_status=0
case $reason in
MEDIUM) # Change of interface media type
;;
PREINIT) # Config. interface prior to contacting DHCP server
;;
ARPSEND) # Check offered IP not already in use via arp (how?)
;;
ARPCHECK) # Did we get a response to ARPSEND?
;;
BOUND) # Received initial config from DHCP server
set_host_name ;
;;
RENEW) # Received change to configuration from DHCP server
set_host_name ;
;;
REBIND) # Bound to a different DHCP server
set_host_name ;
;;
REBOOT) # Renewed previous lease after reboot
set_host_name ;
;;
EXPIRE) # Can't get a new/replacement lease
;;
FAIL) # Can't contact DHCP server or can't get valid lease
;;
TIMEOUT) # Can't contact DHCP server, but have saved lease to reuse
set_host_name ;
;;
*)
$LOGGER "unknown reason \"$reason\" for calling dhclient-script"
exit_status=1
;;
esac
#
# That's All Folks!
#
Matthew
--
Certe, Toto, sentio nos in Kansate non iam adesse.
Dr. Matthew Seaman, Inpharmatica Ltd, 60 Charlotte St, London, W1P 2AX
Tel: +44 171 631 4644 x229 Fax: +44 171 631 4844
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