#!/bin/ksh
# $Id: hosts,v 1.14 2011/08/19 15:53:19 ksb Exp $
# We're a netlint plugin that checks the validity of /etc/hosts.    (petef,ksb)

#****p* netlint/hosts
# NAME
#   hosts
# DESCRIPTION
#   The /etc/hosts file on each node should contain just enough information to
#   boot a node. All the network interfaces on the node, the special enter for
#   localhost, and maybe any hosts on any locally attached black
#   (non-routable) networks.
#***

PROGNAME=`basename $0`
: ${CARP:=echo}
: ${HOSTFSPATH:=/etc/hosts}
export HOSTFSPATH CARP
if [ _"$1" = _"-V" ]; then
	echo "$PROGNAME: "'$Id: hosts,v 1.14 2011/08/19 15:53:19 ksb Exp $'
	[ -f $HOSTFSPATH ] || echo "$PROGNAME: no $HOSTFSPATH found!"
	exit 0
fi

HOST=`hostname`
export HOST

#****a* hosts/HOSTS_MISSING
# NAME
#   HOSTS_MISSING
# FORMAT
#   HOSTS_MISSING: path
# DESCRIPTION
#   The complaint is that the hosts file is completely missing on the node.
# IMPACT
#   This is always bad.
# REMEDIATION
#   Install a hosts file or the apropos symbolic link.
#***

if [ ! -s $HOSTFSPATH ] ; then
	$CARP "HOSTS_MISSING: $HOSTFSPATH"
	exit 0
fi

#****a* hosts/HOSTS_IP
# NAME
#   HOSTS_IP
# FORMAT
#   HOSTS_IP: ip path
# DESCRIPTION
#   The netlint program maps each interface's IP in /etc/hosts to be sure that
#   the system can reverse map all the interfaces back to itself at boot time.
#   This error indicates that some IP addresses bound to a local interface do
#   not map to that host.
#
#   This might be fine for virtual IPs (VIPs) that move between servers, or for
#   a host that is holding another host's IP address for some other reason.
#   These are noted in site policy in ~netlint/lib/reverse/ where there is a
#   file for each host and a list of IPs that can be ignored for that host.
# IMPACT
#   Having a wrong mapping in the hosts file is bad as is can cause the system
#   to duplicate the IP of another host on the network. Missing a mapping in
#   /etc/hosts can cause a longer than normal boot time, as the host times out
#   on a resolver query before the network is fully lighted.
# REMEDIATION
#   * Update /etc/hosts (a comment line is accepted here as well)
#   * Update site policy
#   * Update the black network zone and rebuild it from the master source.
# SEE ALSO
#   /usr/msrc/etc/hostname for the code to generate the black network address maps.
#***

# Get a list of IPs our hostname resolves to
echo ${IP_LIST:-`nslookup $HOST 2>/dev/null |
	egrep "^Addr[es]*:[	 ]*" |
	sed -e '1d' -e 's,^Addr[es]*: *,,' -e 'y/,/ /' -e 's,[	 ][	 ]*, ,'`} |
	tr ' ' '\012' |
	sed -e 's,\.,\\.,g' |
	xapply -f -S/bin/sh 'sed -e "s/^#+//" $HOSTFSPATH |egrep "^%1[	 ][	 ]*$HOST([	 ].*$|$)" >/dev/null || echo "HOSTS_IP: %1 $HOSTFSPATH"' - |
	sed -e 's,\\\.,.,g' | fgrep -v '0.0.0.0' |
	xapply -f -S/bin/sh '$CARP "%1"' -

#****a* hosts/HOSTS_EXTRA
# NAME
#   HOSTS_EXTRA
# FORMAT
#   HOSTS_EXTRA: ip path
# DESCRIPTION
#   The netlint program carps about IP address mapped in a hosts file
#   that are not on a directly attached network.  These should all be
#   resolved with a name server, really.
#
# IMPACT
#   Having a wrong mapping in the hosts file is bad as is can cause the system
#   to contact a dead or incorrect host at boot.
# REMEDIATION
#   * Update /etc/hosts to remove the off-net mapping
#   * Update site policy
#   * If a hard coded IP is actually necessary, append ##netlint_ignore to the host line.
# BUGS
#   * We don't handle IPV6 addresses (yet)
#***
listy=/tmp/nlhl$((RANDOM%1000))
while [ -e $listy ] ; do
	listy="$listy,$((RANDOM%100))"
done
trap 'rm $listy.*' EXIT
sed -n -e '/##netlint_ignore/d;s/#.*//;s/^[         ]*//;/^$/d' -e 's/^\([0-9.]*\)[         ].*/\1/p' <$HOSTFSPATH >$listy.res
xapply -P1 -S/bin/ksh "	# %1
	. $NETLINT_FUNCS
	while read IP ; do
		[ %[1/1] = \`AndIt \$IP %[1/2]\` ] || echo \$IP
	done <$listy.res >$listy.%u
	mv $listy.%u $listy.res
	" $SUBNET_LIST 127.0.0.0/8
if [ -s $listy.res ] ; then
	xapply -f -S/bin/sh '$CARP "HOSTS_EXTRA: %1 $HOSTFSPATH"' $listy.res
fi

exit 0