#!/bin/bash
#Copyright 2003 William Stearns <wstearns@pobox.com>
#Released under the GPL.

Me='icmpfwdchk'
MyVersion='0.3.3'

[ -r /etc/firebricks/firebricks.conf ] &&			. /etc/firebricks/firebricks.conf
[ -r /etc/firebricks/$Me.conf ] &&				. /etc/firebricks/$Me.conf
[ -r ${FBLibDir:-'/usr/lib/firebricks/'}/firebrickslib ] &&	. ${FBLibDir:-'/usr/lib/firebricks/'}/firebrickslib
if [ -z "$FBLibVer" ]; then
	echo 'It looks like firebrickslib was not loaded, why?  Exiting' >&2
	exit 1
fi

for OneTask in $Tasks ; do
	case "$OneTask" in
	link)
		$IptablesBin -N $Me >/dev/null 2>&1
		$IptablesBin $AppIn FORWARD -p icmp						-j $Me
		;;
	unlink)
		$IptablesBin -D FORWARD -p icmp							-j $Me
		$IptablesBin -X $Me >/dev/null 2>&1
		;;
	create)
		echo "Starting $Me" >&2
		FlushOrNewChain $Me
		LogAs='icmp-frag'	$Ipt -A $Me -p icmp -f					$Tail
		LogAs='icmp-fwd-redir'	$Ipt -A $Me -p icmp --icmp-type redirect		$Tail
		;;
	destroy)
		echo "Stopping $Me" >&2
		DestroyChain $Me
		;;
	renamechain)
		TempChain="$Me-$RANDOM"
		echo "Replacing existing rules in $Me with new rules" >&2
		$IptablesBin -E $Me $TempChain
		;;
	replacelinks)
		if [ -z "$TempChain" ]; then
			echo "No temporary chain to relink in $Me replacelinks, replace operation incomplete." >&2
		elif ! $IptablesBin -L $Me -n >/dev/null 2>&1 ; then
			echo "No $Me chain in $Me, replace operation incomplete." >&2
		elif ! $IptablesBin -L $TempChain -n >/dev/null 2>&1 ; then
			echo "No $TempChain chain in $Me, replace operation incomplete." >&2
		elif [ "`$IptablesBin -L FORWARD -n --line-numbers | grep $TempChain | wc -l`" -ne 1 ]; then
			echo "Too few/many references to $TempChain in FORWARD in $Me replacelinks, replace operation incomplete." >&2
		else
			$IptablesBin -R FORWARD `$IptablesBin -L FORWARD -n --line-numbers | grep $TempChain | awk '{print $1}'` -p icmp	-j $Me
			DestroyChain $TempChain
			unset TempChain
		fi
		;;
	status)
		if $IptablesBin -L $Me -n >/dev/null 2>&1 ; then
			echo "$Me created" >&2
		else
			echo "$Me destroyed" >&2
		fi
		;;
	version)
		echo "$Me $MyVersion, firebrickslib $FBLibVer" >&2
		;;
	help)
		DefaultHelp
		cat <<EOTEXT >&2
	The $Me module checks only icmp packets being forwarded through
this router.  It specifically disallows fragmented ICMP and ICMP
redirects.  Both should be universally safe to forward.
EOTEXT
		;;
	*)
		echo "Unknown action $Action in $Me, no action taken." >&2
		;;
	esac
done