vpnc-script

#!/bin/sh
#
# Originally part of vpnc source code:
# © 2005-2012 Maurice Massar, Jörg Mayer, Antonio Borneo et al.
# © 2009-2012 David Woodhouse <dwmw2@infradead.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
################
#
# List of parameters passed through environment
#* reason                       -- why this script was called, one of: pre-init connect disconnect reconnect attempt-reconnect
#* VPNGATEWAY                   -- vpn gateway address (always present)
#* TUNDEV                       -- tunnel device (always present)
#* INTERNAL_IP4_ADDRESS         -- address (always present)
#* INTERNAL_IP4_MTU             -- mtu (often unset)
#* INTERNAL_IP4_NETMASK         -- netmask (often unset)
#* INTERNAL_IP4_NETMASKLEN      -- netmask length (often unset)
#* INTERNAL_IP4_NETADDR         -- address of network (only present if netmask is set)
#* INTERNAL_IP4_DNS             -- list of dns servers
#* INTERNAL_IP4_NBNS            -- list of wins servers
#* INTERNAL_IP6_ADDRESS         -- IPv6 address
#* INTERNAL_IP6_NETMASK         -- IPv6 netmask
#* INTERNAL_IP6_DNS             -- IPv6 list of dns servers
#* CISCO_DEF_DOMAIN             -- default domain name
#* CISCO_BANNER                 -- banner from server
#* CISCO_SPLIT_INC              -- number of networks in split-network-list
#* CISCO_SPLIT_INC_%d_ADDR      -- network address
#* CISCO_SPLIT_INC_%d_MASK      -- subnet mask (for example: 255.255.255.0)
#* CISCO_SPLIT_INC_%d_MASKLEN   -- subnet masklen (for example: 24)
#* CISCO_SPLIT_INC_%d_PROTOCOL  -- protocol (often just 0)
#* CISCO_SPLIT_INC_%d_SPORT     -- source port (often just 0)
#* CISCO_SPLIT_INC_%d_DPORT     -- destination port (often just 0)
#* CISCO_IPV6_SPLIT_INC         -- number of networks in IPv6 split-network-list
#* CISCO_IPV6_SPLIT_INC_%d_ADDR -- IPv6 network address
#* CISCO_IPV6_SPLIT_INC_$%d_MASKLEN -- IPv6 subnet masklen

# FIXMEs:

# Section A: route handling

# 1) The 3 values CISCO_SPLIT_INC_%d_PROTOCOL/SPORT/DPORT are currently being ignored
#   In order to use them, we'll probably need os specific solutions
#   * Linux: iptables -t mangle -I PREROUTING <conditions> -j ROUTE --oif $TUNDEV
#       This would be an *alternative* to changing the routes (and thus 2) and 3)
#       shouldn't be relevant at all)
# 2) There are two different functions to set routes: generic routes and the
#   default route. Why isn't the defaultroute handled via the generic route case?
# 3) In the split tunnel case, all routes but the default route might get replaced
#   without getting restored later. We should explicitely check and save them just
#   like the defaultroute
# 4) Replies to a dhcp-server should never be sent into the tunnel

# Section B: Split DNS handling

# 1) Maybe dnsmasq can do something like that
# 2) Parse dns packets going out via tunnel and redirect them to original dns-server

#env | sort
#set -x

# =========== script (variable) setup ====================================

PATH=/sbin:/usr/sbin:$PATH

OS="`uname -s`"

HOOKS_DIR=/etc/vpnc
DEFAULT_ROUTE_FILE=/var/run/vpnc/defaultroute
RESOLV_CONF_BACKUP=/var/run/vpnc/resolv.conf-backup
SCRIPTNAME=`basename $0`

# some systems, eg. Darwin & FreeBSD, prune /var/run on boot
if [ ! -d "/var/run/vpnc" ]; then
	mkdir -p /var/run/vpnc
	[ -x /sbin/restorecon ] && /sbin/restorecon /var/run/vpnc
fi

if ifconfig --help 2>&1 | grep BusyBox > /dev/null; then
	ifconfig_syntax_inet=""
else
	ifconfig_syntax_inet="inet"
fi

if [ "$OS" = "Linux" ]; then
	IPROUTE="`which ip 2> /dev/null | grep '^/'`"
	ifconfig_syntax_ptp="pointopoint"
	route_syntax_gw="gw"
	route_syntax_del="del"
	route_syntax_netmask="netmask"
else
	# iproute2 is Linux only; if `which ip` returns something on another OS, it's likely an unrelated tool
	# (see https://github.com/dlenski/openconnect/issues/132#issuecomment-470475009)
	IPROUTE=""
	ifconfig_syntax_ptp=""
	route_syntax_gw=""
	route_syntax_del="delete"
	route_syntax_netmask="-netmask"
fi
if [ "$OS" = "SunOS" ]; then
	route_syntax_interface="-interface"
	ifconfig_syntax_ptpv6="$INTERNAL_IP6_ADDRESS"
else
	route_syntax_interface=""
	ifconfig_syntax_ptpv6=""
fi

grep ^hosts /etc/nsswitch.conf 2>/dev/null|grep resolve >/dev/null 2>&1
if [ $? = 0 ];then
	RESOLVEDENABLED=1
else
	RESOLVEDENABLED=0
fi

if [ -r /etc/openwrt_release ] && [ -n "$OPENWRT_INTERFACE" ]; then
        . /etc/functions.sh
	include /lib/network
	MODIFYRESOLVCONF=modify_resolvconf_openwrt
	RESTORERESOLVCONF=restore_resolvconf_openwrt
elif [ -x /usr/bin/busctl ] && [ ${RESOLVEDENABLED} = 1 ]; then
	# For systemd-resolved (version 229 and above)
	MODIFYRESOLVCONF=modify_resolved_manager
	RESTORERESOLVCONF=restore_resolved_manager
elif [ -x /sbin/resolvconf ]; then
	# Optional tool on Debian, Ubuntu, Gentoo and FreeBSD
	MODIFYRESOLVCONF=modify_resolvconf_manager
	RESTORERESOLVCONF=restore_resolvconf_manager
elif [ -x /sbin/netconfig ] && [ ! -f /etc/slackware-version ]; then
	# tool on Suse after 11.1
	# Slackware's netconfig is an unrelated tool that should not be invoked here
	# (see https://www.linuxquestions.org/questions/slackware-14/vpnc-on-slackware-14-2-is-bringing-up-network-configuration-dialog-each-time-4175595447/#post5646866)
	MODIFYRESOLVCONF=modify_resolvconf_suse_netconfig
	RESTORERESOLVCONF=restore_resolvconf_suse_netconfig
elif [ -x /sbin/modify_resolvconf ]; then
	# Mandatory tool on Suse earlier than 11.1
	MODIFYRESOLVCONF=modify_resolvconf_suse
	RESTORERESOLVCONF=restore_resolvconf_suse
elif [ -x /usr/sbin/unbound-control ] && /usr/sbin/unbound-control status > /dev/null 2>&1; then
	MODIFYRESOLVCONF=modify_resolvconf_unbound
	RESTORERESOLVCONF=restore_resolvconf_unbound
else # Generic for any OS
	MODIFYRESOLVCONF=modify_resolvconf_generic
	RESTORERESOLVCONF=restore_resolvconf_generic
fi


# =========== script hooks =================================================

run_hooks() {
	HOOK="$1"

	if [ -d ${HOOKS_DIR}/${HOOK}.d ]; then
	    for script in ${HOOKS_DIR}/${HOOK}.d/* ; do
		[ -f $script ] && . $script
	    done
	fi
}

# =========== tunnel interface handling ====================================

do_ifconfig() {
	if [ -n "$INTERNAL_IP4_MTU" ]; then
		MTU=$INTERNAL_IP4_MTU
	elif [ -n "$IPROUTE" ]; then
		MTUDEV=`$IPROUTE route get "$VPNGATEWAY" | sed -ne 's/^.*dev \([a-z0-9]*\).*$/\1/p'`
		MTU=`$IPROUTE link show "$MTUDEV" | sed -ne 's/^.*mtu \([[:digit:]]\+\).*$/\1/p'`
		if [ -n "$MTU" ]; then
			MTU=`expr $MTU - 88`
		fi
	fi

	if [ -z "$MTU" ]; then
		MTU=1412
	fi

	# Point to point interface require a netmask of 255.255.255.255 on some systems
	if [ -n "$IPROUTE" ]; then
		$IPROUTE link set dev "$TUNDEV" up mtu "$MTU"
		$IPROUTE addr add "$INTERNAL_IP4_ADDRESS/32" peer "$INTERNAL_IP4_ADDRESS" dev "$TUNDEV"
	else
		ifconfig "$TUNDEV" ${ifconfig_syntax_inet} "$INTERNAL_IP4_ADDRESS" $ifconfig_syntax_ptp "$INTERNAL_IP4_ADDRESS" netmask 255.255.255.255 mtu ${MTU} up
	fi

	if [ -n "$INTERNAL_IP4_NETMASK" ]; then
		set_network_route "$INTERNAL_IP4_NETADDR" "$INTERNAL_IP4_NETMASK" "$INTERNAL_IP4_NETMASKLEN" "$TUNDEV"
	fi

	# If the netmask is provided, it contains the address _and_ netmask
	if [ -n "$INTERNAL_IP6_ADDRESS" ] && [ -z "$INTERNAL_IP6_NETMASK" ]; then
	    INTERNAL_IP6_NETMASK="$INTERNAL_IP6_ADDRESS/128"
	fi
	if [ -n "$INTERNAL_IP6_NETMASK" ]; then
	    if [ -n "$IPROUTE" ]; then
		$IPROUTE -6 addr add $INTERNAL_IP6_NETMASK dev $TUNDEV
	    else
		# Unlike for Legacy IP, we don't specify the dest_address
		# here on *BSD. OpenBSD for one will refuse to accept
		# incoming packets to that address if we do.
		# OpenVPN does the same (gives dest_address for Legacy IP
		# but not for IPv6).
		# Only Solaris needs it; hence $ifconfig_syntax_ptpv6
	        ifconfig "$TUNDEV" inet6 $INTERNAL_IP6_NETMASK $ifconfig_syntax_ptpv6 mtu $MTU up
	    fi
	fi
}

destroy_tun_device() {
	case "$OS" in
	NetBSD|OpenBSD) # and probably others...
		ifconfig "$TUNDEV" destroy
		;;
	FreeBSD)
		ifconfig "$TUNDEV" destroy > /dev/null 2>&1 &
		;;
	esac
}

# =========== route handling ====================================

if [ -n "$IPROUTE" ]; then
	fix_ip_get_output () {
		sed -e 's/ /\n/g' | \
		    sed -ne "1 s|\$|${1}|p;/via/{N;p};/dev/{N;p};/src/{N;p};/mtu/{N;p}"
	}

	set_vpngateway_route() {
		$IPROUTE route add `$IPROUTE route get "$VPNGATEWAY" | fix_ip_get_output`
		$IPROUTE route flush cache 2>/dev/null
	}

	del_vpngateway_route() {
		$IPROUTE route $route_syntax_del "$VPNGATEWAY"
		$IPROUTE route flush cache 2>/dev/null
	}

	set_default_route() {
		$IPROUTE route | grep '^default' | fix_ip_get_output > "$DEFAULT_ROUTE_FILE"
		$IPROUTE route replace default dev "$TUNDEV"
		$IPROUTE route flush cache 2>/dev/null
	}

	set_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		NETDEV="$4"
		NETGW="$5"
		if [ -n "$NETGW" ]; then
			$IPROUTE route replace "$NETWORK/$NETMASKLEN" dev "$NETDEV" via "$NETGW"
		else
			$IPROUTE route replace "$NETWORK/$NETMASKLEN" dev "$NETDEV"
		fi
		$IPROUTE route flush cache 2>/dev/null
	}

	set_exclude_route() {
		# add explicit route to keep current routing for this target
		# (keep traffic separate from VPN tunnel)
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		$IPROUTE route add `$IPROUTE route get "$NETWORK" | fix_ip_get_output "/$NETMASKLEN"`
		$IPROUTE route flush cache 2>/dev/null
	}

	del_exclude_route() {
		# FIXME: In theory, this could delete existing routes which are
		# identical to split-exclude routes specificed by VPNGATEWAY
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		$IPROUTE route $route_syntax_del "$NETWORK/$NETMASKLEN"
		$IPROUTE route flush cache 2>/dev/null
	}

	reset_default_route() {
		if [ -s "$DEFAULT_ROUTE_FILE" ]; then
			$IPROUTE route replace `cat "$DEFAULT_ROUTE_FILE"`
			$IPROUTE route flush cache 2>/dev/null
			rm -f -- "$DEFAULT_ROUTE_FILE"
		fi
	}

	del_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		NETDEV="$4"
		$IPROUTE route $route_syntax_del "$NETWORK/$NETMASKLEN" dev "$NETDEV"
		$IPROUTE route flush cache 2>/dev/null
	}

	set_ipv6_default_route() {
		# We don't save/restore IPv6 default route; just add a higher-priority one.
		$IPROUTE -6 route add default dev "$TUNDEV" metric 1
		$IPROUTE -6 route flush cache 2>/dev/null
	}

	set_ipv6_network_route() {
		NETWORK="$1"
		NETMASKLEN="$2"
		NETDEV="$3"
		NETGW="$4"
		if [ -n "$NETGW" ]; then
			$IPROUTE -6 route replace "$NETWORK/$NETMASKLEN" dev "$NETDEV" via "$NETGW"
		else
			$IPROUTE -6 route replace "$NETWORK/$NETMASKLEN" dev "$NETDEV"
		fi
		$IPROUTE route flush cache 2>/dev/null
	}

	set_ipv6_exclude_route() {
		# add explicit route to keep current routing for this target
		# (keep traffic separate from VPN tunnel)
		NETWORK="$1"
		NETMASKLEN="$2"
		$IPROUTE -6 route add `$IPROUTE route get "$NETWORK" | fix_ip_get_output "/$NETMASKLEN"`
		$IPROUTE route flush cache 2>/dev/null
	}

	reset_ipv6_default_route() {
		$IPROUTE -6 route del default dev "$TUNDEV"
		$IPROUTE route flush cache 2>/dev/null
	}

	del_ipv6_network_route() {
		NETWORK="$1"
		NETMASKLEN="$2"
		NETDEV="$3"
		$IPROUTE -6 route del "$NETWORK/$NETMASKLEN" dev "$NETDEV"
		$IPROUTE -6 route flush cache 2>/dev/null
	}

	del_ipv6_exclude_route() {
		# FIXME: In theory, this could delete existing routes which are
		# identical to split-exclude routes specificed by VPNGATEWAY
		NETWORK="$1"
		NETMASKLEN="$2"
		$IPROUTE -6 route del "$NETWORK/$NETMASKLEN"
		$IPROUTE -6 route flush cache 2>/dev/null
	}
else # use route command
	get_default_gw() {
		# isn't -n supposed to give --numeric output?
		# apperently not...
		# Get rid of lines containing IPv6 addresses (':')
		netstat -r -n | awk '/:/ { next; } /^(default|0\.0\.0\.0)/ { print $2; }'
	}

	set_vpngateway_route() {
		route add -host "$VPNGATEWAY" $route_syntax_gw "`get_default_gw`"
	}

	del_vpngateway_route() {
		route $route_syntax_del -host "$VPNGATEWAY" $route_syntax_gw "`get_default_gw`"
	}

	set_default_route() {
		DEFAULTGW="`get_default_gw`"
		echo "$DEFAULTGW" > "$DEFAULT_ROUTE_FILE"
		route $route_syntax_del default $route_syntax_gw "$DEFAULTGW"
		route add default $route_syntax_gw "$INTERNAL_IP4_ADDRESS" $route_syntax_interface
	}

	set_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		if [ -n "$5" ]; then
			NETGW="$5"
		else
			NETGW="$INTERNAL_IP4_ADDRESS"
		fi
		route add -net "$NETWORK" $route_syntax_netmask "$NETMASK" $route_syntax_gw "$NETGW" $route_syntax_interface
	}

	set_exclude_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		if [ -z "$DEFAULTGW" ]; then
			DEFAULTGW="`get_default_gw`"
		fi
		# Add explicit route to keep traffic for this target separate
		# from tunnel. FIXME: We use default gateway - this is our best
		# guess in absence of "ip" command to query effective route.
		route add -net "$NETWORK" $route_syntax_netmask "$NETMASK" $route_syntax_gw "$DEFAULTGW" $route_syntax_interface
	}

	del_exclude_route() {
		# FIXME: This can delete existing routes in case they're
		# identical to split-exclude routes specified by VPNGATEWAY
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		route $route_syntax_del -net "$NETWORK" $route_syntax_netmask "$NETMASK"
	}

	reset_default_route() {
		if [ -s "$DEFAULT_ROUTE_FILE" ]; then
			route $route_syntax_del default $route_syntax_gw "`get_default_gw`" $route_syntax_interface
			route add default $route_syntax_gw `cat "$DEFAULT_ROUTE_FILE"`
			rm -f -- "$DEFAULT_ROUTE_FILE"
		fi
	}

	del_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		if [ -n "$5" ]; then
			NETGW="$5"
		else
			NETGW="$INTERNAL_IP4_ADDRESS"
		fi
		route $route_syntax_del -net "$NETWORK" $route_syntax_netmask "$NETMASK" $route_syntax_gw "$NETGW"
	}

	set_ipv6_default_route() {
		route add -inet6 default "$INTERNAL_IP6_ADDRESS" $route_syntax_interface
	}

	set_ipv6_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		if [ -n "$4" ]; then
			NETGW="$4"
		else
			NETGW="$INTERNAL_IP6_ADDRESS"
		fi

		route add -inet6 -net "$NETWORK/$NETMASK" "$NETGW" $route_syntax_interface
		:
	}

	set_ipv6_exclude_route() {
		NETWORK="$1"
		NETMASK="$2"
		# Add explicit route to keep traffic for this target separate
		# from tunnel. FIXME: We use default gateway - this is our best
		# guess in absence of "ip" command to query effective route.
		route add -inet6 -net "$NETWORK/$NETMASK" "`get_default_gw`" $route_syntax_interface
		:
	}

	reset_ipv6_default_route() {
		route $route_syntax_del -inet6 default "$INTERNAL_IP6_ADDRESS"
		:
	}

	del_ipv6_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		if [ -n "$4" ]; then
			NETGW="$4"
		else
			NETGW="$INTERNAL_IP6_ADDRESS"
		fi
		route $route_syntax_del -inet6 "$NETWORK/$NETMASK" "$NETGW"
		:
	}

	del_ipv6_exclude_route() {
		NETWORK="$1"
		NETMASK="$2"
		route $route_syntax_del -inet6 "$NETWORK/$NETMASK"
		:
	}

fi

# =========== resolv.conf handling ====================================

# =========== resolv.conf handling for any OS =========================

modify_resolvconf_generic() {
	grep '^#@VPNC_GENERATED@' /etc/resolv.conf > /dev/null 2>&1 || cp -- /etc/resolv.conf "$RESOLV_CONF_BACKUP"
	NEW_RESOLVCONF="#@VPNC_GENERATED@ -- this file is generated by vpnc
# and will be overwritten by vpnc
# as long as the above mark is intact"

	DOMAINS="$CISCO_DEF_DOMAIN"

	exec 6< "$RESOLV_CONF_BACKUP"
	while read LINE <&6 ; do
		case "$LINE" in
			# omit; we will overwrite these
			nameserver*) ;;
			# extract listed domains and prepend to list
			domain* | search*) DOMAINS="${LINE#* } $DOMAINS" ;;
			# retain other lines
			*) NEW_RESOLVCONF="$NEW_RESOLVCONF
$LINE" ;;
		esac
	done
	exec 6<&-

	for i in $INTERNAL_IP4_DNS ; do
		NEW_RESOLVCONF="$NEW_RESOLVCONF
nameserver $i"
	done
	# note that "search" is mutually exclusive with "domain";
	# "search" allows multiple domains to be listed, so use that
	if [ -n "$DOMAINS" ]; then
		NEW_RESOLVCONF="$NEW_RESOLVCONF
search $DOMAINS"
	fi
	echo "$NEW_RESOLVCONF" > /etc/resolv.conf

	if [ "$OS" = "Darwin" ]; then
		case "`uname -r`" in
			# Skip for pre-10.4 systems
			4.*|5.*|6.*|7.*)
				;;
			# 10.4 and later require use of scutil for DNS to work properly
			*)
				OVERRIDE_PRIMARY=""
				if [ -n "$CISCO_SPLIT_INC" ]; then
					if [ $CISCO_SPLIT_INC -lt 1 ]; then
						# Must override for correct default route
						# Cannot use multiple DNS matching in this case
						OVERRIDE_PRIMARY='d.add OverridePrimary # 1'
					fi
					# Overriding the default gateway breaks split routing
					OVERRIDE_GATEWAY=""
					# Not overriding the default gateway breaks usage of
					# INTERNAL_IP4_DNS. Prepend INTERNAL_IP4_DNS to list
					# of used DNS servers
					SERVICE=`echo "show State:/Network/Global/IPv4" | scutil | grep -oE '[a-fA-F0-9]{8}-([a-fA-F0-9]{4}-){3}[a-fA-F0-9]{12}'`
					SERVICE_DNS=`echo "show State:/Network/Service/$SERVICE/DNS" | scutil | grep -oE '([0-9]{1,3}[\.]){3}[0-9]{1,3}' | xargs`
					if [ X"$SERVICE_DNS" != X"$INTERNAL_IP4_DNS" ]; then
						scutil >/dev/null 2>&1 <<-EOF
							open
							get State:/Network/Service/$SERVICE/DNS
							d.add ServerAddresses * $INTERNAL_IP4_DNS $SERVICE_DNS
							set State:/Network/Service/$SERVICE/DNS
							close
						EOF
					fi
				else
					# No split routing. Override default gateway
					OVERRIDE_GATEWAY="d.add Router $INTERNAL_IP4_ADDRESS"
				fi
				# Uncomment the following if/fi pair to use multiple
				# DNS matching when available.  When multiple DNS matching
				# is present, anything reading the /etc/resolv.conf file
				# directly will probably not work as intended.
				#if [ -z "$CISCO_DEF_DOMAIN" ]; then
					# Cannot use multiple DNS matching without a domain
					OVERRIDE_PRIMARY='d.add OverridePrimary # 1'
				#fi
				scutil >/dev/null 2>&1 <<-EOF
					open
					d.init
					d.add ServerAddresses * $INTERNAL_IP4_DNS
					set State:/Network/Service/$TUNDEV/DNS
					d.init
					$OVERRIDE_GATEWAY
					d.add Addresses * $INTERNAL_IP4_ADDRESS
					d.add SubnetMasks * 255.255.255.255
					d.add InterfaceName $TUNDEV
					$OVERRIDE_PRIMARY
					set State:/Network/Service/$TUNDEV/IPv4
					close
				EOF
				if [ -n "$CISCO_DEF_DOMAIN" ]; then
					scutil >/dev/null 2>&1 <<-EOF
						open
						get State:/Network/Service/$TUNDEV/DNS
						d.add DomainName $CISCO_DEF_DOMAIN
						d.add SearchDomains * $CISCO_DEF_DOMAIN
						d.add SupplementalMatchDomains * $CISCO_DEF_DOMAIN
						set State:/Network/Service/$TUNDEV/DNS
						close
					EOF
				fi
				;;
		esac
	fi
}

restore_resolvconf_generic() {
	if [ ! -f "$RESOLV_CONF_BACKUP" ]; then
		return
	fi
	grep '^#@VPNC_GENERATED@' /etc/resolv.conf > /dev/null 2>&1 && cat "$RESOLV_CONF_BACKUP" > /etc/resolv.conf
	rm -f -- "$RESOLV_CONF_BACKUP"

	if [ "$OS" = "Darwin" ]; then
		case "`uname -r`" in
			# Skip for pre-10.4 systems
			4.*|5.*|6.*|7.*)
				;;
			# 10.4 and later require use of scutil for DNS to work properly
			*)
				scutil >/dev/null 2>&1 <<-EOF
					open
					remove State:/Network/Service/$TUNDEV/IPv4
					remove State:/Network/Service/$TUNDEV/DNS
					close
				EOF
				# Split routing required prepending of INTERNAL_IP4_DNS
				# to list of used DNS servers
				if [ -n "$CISCO_SPLIT_INC" ]; then
					SERVICE=`echo "show State:/Network/Global/IPv4" | scutil | grep -oE '[a-fA-F0-9]{8}-([a-fA-F0-9]{4}-){3}[a-fA-F0-9]{12}'`
					SERVICE_DNS=`echo "show State:/Network/Service/$SERVICE/DNS" | scutil | grep -oE '([0-9]{1,3}[\.]){3}[0-9]{1,3}' | xargs`
					if [ X"$SERVICE_DNS" != X"$INTERNAL_IP4_DNS" ]; then
						scutil >/dev/null 2>&1 <<-EOF
							open
							get State:/Network/Service/$SERVICE/DNS
							d.add ServerAddresses * ${SERVICE_DNS##$INTERNAL_IP4_DNS}
							set State:/Network/Service/$SERVICE/DNS
							close
						EOF
					fi
				fi
				;;
		esac
	fi
}
# === resolv.conf handling via /sbin/netconfig (Suse 11.1) =====================

# Suse provides a script that modifies resolv.conf. Use it because it will
# restart/reload all other services that care about it (e.g. lwresd).  [unclear if this is still true, but probably --mlk]

modify_resolvconf_suse_netconfig()
{
	/sbin/netconfig modify -s vpnc -i "$TUNDEV" <<-EOF
		INTERFACE='$TUNDEV'
		DNSSERVERS='$INTERNAL_IP4_DNS'
		DNSDOMAIN='$CISCO_DEF_DOMAIN'
		EOF
}
# Restore resolv.conf to old contents on Suse
restore_resolvconf_suse_netconfig()
{
	/sbin/netconfig remove -s vpnc -i "$TUNDEV"
}

# === resolv.conf handling via /sbin/modify_resolvconf (Suse) =====================

# Suse provides a script that modifies resolv.conf. Use it because it will
# restart/reload all other services that care about it (e.g. lwresd).

modify_resolvconf_suse()
{
	FULL_SCRIPTNAME=`readlink -f $0`
	RESOLV_OPTS=''
	test -n "$INTERNAL_IP4_DNS" && RESOLV_OPTS="-n \"$INTERNAL_IP4_DNS\""
	test -n "$CISCO_DEF_DOMAIN" && RESOLV_OPTS="$RESOLV_OPTS -d $CISCO_DEF_DOMAIN"
	test -n "$RESOLV_OPTS" && eval /sbin/modify_resolvconf modify -s vpnc -p $SCRIPTNAME -f $FULL_SCRIPTNAME -e $TUNDEV $RESOLV_OPTS -t \"This file was created by $SCRIPTNAME\"
}

# Restore resolv.conf to old contents on Suse
restore_resolvconf_suse()
{
	FULL_SCRIPTNAME=`readlink -f $0`
	/sbin/modify_resolvconf restore -s vpnc -p $SCRIPTNAME -f $FULL_SCRIPTNAME -e $TUNDEV
}

# === resolv.conf handling via UCI (OpenWRT) =========

modify_resolvconf_openwrt() {
	add_dns $OPENWRT_INTERFACE $INTERNAL_IP4_DNS
}

restore_resolvconf_openwrt() {
	remove_dns $OPENWRT_INTERFACE
}
# === resolv.conf handling via /sbin/resolvconf (Debian, Ubuntu, Gentoo)) =========

modify_resolvconf_manager() {
	NEW_RESOLVCONF=""
	for i in $INTERNAL_IP4_DNS; do
		NEW_RESOLVCONF="$NEW_RESOLVCONF
nameserver $i"
	done
	if [ -n "$CISCO_DEF_DOMAIN" ]; then
		NEW_RESOLVCONF="$NEW_RESOLVCONF
search $CISCO_DEF_DOMAIN"
	fi
	echo "$NEW_RESOLVCONF" | /sbin/resolvconf -a $TUNDEV
}

restore_resolvconf_manager() {
	/sbin/resolvconf -d $TUNDEV
}

AF_INET=2

get_if_index() {
	local link
	link="$(ip link show dev "$1")" || return $?
	echo ${link} | awk -F: '{print $1}'
}

busctl_call() {
	local dest node
	dest=org.freedesktop.resolve1
	node=/org/freedesktop/resolve1
	busctl call "$dest" "${node}" "${dest}.Manager" "$@"
}

busctl_set_nameservers() {
	local if_index addresses args addr
	if_index=$1
	shift
	addresses="$@"
	args="$if_index $#"
	for addr in ${addresses}; do
		args="$args ${AF_INET} 4 $(echo $addr | sed 's/[.]/ /g')"
	done
	busctl_call SetLinkDNS 'ia(iay)' ${args}
}

busctl_set_search() {
	local if_index domains args domain
	if_index=$1
	shift
	domains="$@"
	args="$if_index $#"
	for domain in ${domains}; do
		args="$args ${domain} false"
	done
	busctl_call SetLinkDomains 'ia(sb)' ${args}
}

modify_resolved_manager() {
	local if_index
	if_index=$(get_if_index $TUNDEV)
	busctl_set_nameservers $if_index $INTERNAL_IP4_DNS
	if [ -n "$CISCO_DEF_DOMAIN" ]; then
		busctl_set_search $if_index $CISCO_DEF_DOMAIN
	fi
}

restore_resolved_manager() {
	local if_index
	if_index=$(get_if_index $TUNDEV)
	busctl_call RevertLink 'i' $if_index
}

# === resolv.conf handling via unbound =========

modify_resolvconf_unbound() {
	if [ -n "$CISCO_DEF_DOMAIN" ]; then
		/usr/sbin/unbound-control forward_add +i ${CISCO_DEF_DOMAIN} ${INTERNAL_IP4_DNS}
		/usr/sbin/unbound-control flush_requestlist
		/usr/sbin/unbound-control flush_zone ${CISCO_DEF_DOMAIN}
	fi
}

restore_resolvconf_unbound() {
	if [ -n "$CISCO_DEF_DOMAIN" ]; then
		/usr/sbin/unbound-control forward_remove +i ${CISCO_DEF_DOMAIN}
		/usr/sbin/unbound-control flush_zone ${CISCO_DEF_DOMAIN}
		/usr/sbin/unbound-control flush_requestlist
	fi
}

# ========= Toplevel state handling  =======================================

kernel_is_2_6_or_above() {
	case `uname -r` in
		1.*|2.[012345]*)
			return 1
			;;
		*)
			return 0
			;;
	esac
}

do_pre_init() {
	if [ "$OS" = "Linux" ]; then
		if (exec 6< /dev/net/tun) > /dev/null 2>&1 ; then
			:
		else # can't open /dev/net/tun
			test -e /proc/sys/kernel/modprobe && `cat /proc/sys/kernel/modprobe` tun 2>/dev/null
			# fix for broken devfs in kernel 2.6.x
			if [ "`readlink /dev/net/tun`" = misc/net/tun \
				-a ! -e /dev/net/misc/net/tun -a -e /dev/misc/net/tun ] ; then
				ln -sf /dev/misc/net/tun /dev/net/tun
			fi
			# make sure tun device exists
			if [ ! -e /dev/net/tun ]; then
				mkdir -p /dev/net
				mknod -m 0640 /dev/net/tun c 10 200
				[ -x /sbin/restorecon ] && /sbin/restorecon /dev/net/tun
			fi
			# workaround for a possible latency caused by udev, sleep max. 10s
			if kernel_is_2_6_or_above ; then
				for x in `seq 100` ; do
					(exec 6<> /dev/net/tun) > /dev/null 2>&1 && break;
					sleep 0.1
				done
			fi
		fi
	elif [ "$OS" = "FreeBSD" ]; then
		if ! kldstat -q -m if_tun > /dev/null; then
			kldload if_tun
		fi

		if ! ifconfig $TUNDEV > /dev/null; then
			ifconfig $TUNDEV create
		fi
	elif [ "$OS" = "GNU/kFreeBSD" ]; then
		if [ ! -e /dev/tun ]; then
			kldload if_tun
		fi
	elif [ "$OS" = "NetBSD" ]; then
		:
	elif [ "$OS" = "OpenBSD" ]; then
		if ! ifconfig $TUNDEV > /dev/null; then
			ifconfig $TUNDEV create
		fi
		:
	elif [ "$OS" = "SunOS" ]; then
		:
	elif [ "$OS" = "Darwin" ]; then
		:
	fi
}

do_connect() {
	if [ -n "$CISCO_BANNER" ]; then
		echo "Connect Banner:"
		echo "$CISCO_BANNER" | while read LINE ; do echo "|" "$LINE" ; done
		echo
	fi

	set_vpngateway_route
	do_ifconfig
	if [ -n "$CISCO_SPLIT_EXC" ]; then
		i=0
		while [ $i -lt $CISCO_SPLIT_EXC ] ; do
			eval NETWORK="\${CISCO_SPLIT_EXC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_EXC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_EXC_${i}_MASKLEN}"
			set_exclude_route "$NETWORK" "$NETMASK" "$NETMASKLEN"
			i=`expr $i + 1`
		done
	fi
	if [ -n "$CISCO_IPV6_SPLIT_EXC" ]; then
		# untested
		i=0
		while [ $i -lt $CISCO_IPV6_SPLIT_EXC ] ; do
			eval NETWORK="\${CISCO_IPV6_SPLIT_EXC_${i}_ADDR}"
			eval NETMASKLEN="\${CISCO_IPV6_SPLIT_EXC_${i}_MASKLEN}"
			set_ipv6_exclude_route "$NETWORK" "$NETMASKLEN"
			i=`expr $i + 1`
		done
	fi
	if [ -n "$CISCO_SPLIT_INC" ]; then
		i=0
		while [ $i -lt $CISCO_SPLIT_INC ] ; do
			eval NETWORK="\${CISCO_SPLIT_INC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_INC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_INC_${i}_MASKLEN}"
			if [ "$NETWORK" != "0.0.0.0" ]; then
				set_network_route "$NETWORK" "$NETMASK" "$NETMASKLEN" "$TUNDEV"
			else
				set_default_route
			fi
			i=`expr $i + 1`
		done
		for i in $INTERNAL_IP4_DNS ; do
			echo "$i" | grep : >/dev/null || \
				set_network_route "$i" "255.255.255.255" "32" "$TUNDEV"
		done
	elif [ -n "$INTERNAL_IP4_ADDRESS" ]; then
		set_default_route
	fi
	if [ -n "$CISCO_IPV6_SPLIT_INC" ]; then
		i=0
		while [ $i -lt $CISCO_IPV6_SPLIT_INC ] ; do
			eval NETWORK="\${CISCO_IPV6_SPLIT_INC_${i}_ADDR}"
			eval NETMASKLEN="\${CISCO_IPV6_SPLIT_INC_${i}_MASKLEN}"
			if [ $NETMASKLEN -eq 0 ]; then
				set_ipv6_default_route
			else
				set_ipv6_network_route "$NETWORK" "$NETMASKLEN" "$TUNDEV"
			fi
			i=`expr $i + 1`
		done
		for i in $INTERNAL_IP4_DNS ; do
			if echo "$i" | grep : >/dev/null; then
				set_ipv6_network_route "$i" "128" "$TUNDEV"
			fi
		done
	elif [ -n "$INTERNAL_IP6_NETMASK" -o -n "$INTERNAL_IP6_ADDRESS" ]; then
		set_ipv6_default_route
	fi

	if [ -n "$INTERNAL_IP4_DNS" ]; then
		$MODIFYRESOLVCONF
	fi
}

do_disconnect() {
	if [ -n "$CISCO_SPLIT_INC" ]; then
		i=0
		while [ $i -lt $CISCO_SPLIT_INC ] ; do
			eval NETWORK="\${CISCO_SPLIT_INC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_INC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_INC_${i}_MASKLEN}"
			if [ "$NETWORK" != "0.0.0.0" ]; then
				# FIXME: This doesn't restore previously overwritten
				#        routes.
				del_network_route "$NETWORK" "$NETMASK" "$NETMASKLEN" "$TUNDEV"
			else
				reset_default_route
			fi
			i=`expr $i + 1`
		done
		for i in $INTERNAL_IP4_DNS ; do
			del_network_route "$i" "255.255.255.255" "32" "$TUNDEV"
		done
	else
		reset_default_route
	fi
	if [ -n "$CISCO_SPLIT_EXC" ]; then
		i=0
		while [ $i -lt $CISCO_SPLIT_EXC ] ; do
			eval NETWORK="\${CISCO_SPLIT_EXC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_EXC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_EXC_${i}_MASKLEN}"
			del_exclude_route "$NETWORK" "$NETMASK" "$NETMASKLEN"
			i=`expr $i + 1`
		done
	fi
	if [ -n "$CISCO_IPV6_SPLIT_EXC" ]; then
		# untested
		i=0
		while [ $i -lt $CISCO_IPV6_SPLIT_EXC ] ; do
			eval NETWORK="\${CISCO_IPV6_SPLIT_EXC_${i}_ADDR}"
			eval NETMASKLEN="\${CISCO_IPV6_SPLIT_EXC_${i}_MASKLEN}"
			del_ipv6_exclude_route "$NETWORK" "$NETMASKLEN"
			i=`expr $i + 1`
		done
	fi
	if [ -n "$CISCO_IPV6_SPLIT_INC" ]; then
		i=0
		while [ $i -lt $CISCO_IPV6_SPLIT_INC ] ; do
			eval NETWORK="\${CISCO_IPV6_SPLIT_INC_${i}_ADDR}"
			eval NETMASKLEN="\${CISCO_IPV6_SPLIT_INC_${i}_MASKLEN}"
			if [ $NETMASKLEN -eq 0 ]; then
				reset_ipv6_default_route
			else
				del_ipv6_network_route "$NETWORK" "$NETMASKLEN" "$TUNDEV"
			fi
			i=`expr $i + 1`
		done
		for i in $INTERNAL_IP6_DNS ; do
			del_ipv6_network_route "$i" "128" "$TUNDEV"
		done
	elif [ -n "$INTERNAL_IP6_NETMASK" -o -n "$INTERNAL_IP6_ADDRESS" ]; then
		reset_ipv6_default_route
	fi

	del_vpngateway_route

	if [ -n "$INTERNAL_IP4_DNS" ]; then
		$RESTORERESOLVCONF
	fi


	if [ -n "$IPROUTE" ]; then
		if [ -n "$INTERNAL_IP4_ADDRESS" ]; then
			$IPROUTE addr del "$INTERNAL_IP4_ADDRESS/255.255.255.255" peer "$INTERNAL_IP4_ADDRESS" dev "$TUNDEV"
		fi
		# If the netmask is provided, it contains the address _and_ netmask
		if [ -n "$INTERNAL_IP6_ADDRESS" ] && [ -z "$INTERNAL_IP6_NETMASK" ]; then
			INTERNAL_IP6_NETMASK="$INTERNAL_IP6_ADDRESS/128"
		fi
		if [ -n "$INTERNAL_IP6_NETMASK" ]; then
			$IPROUTE -6 addr del $INTERNAL_IP6_NETMASK dev $TUNDEV
		fi
	else
		if [ -n "$INTERNAL_IP4_ADDRESS" ]; then
			ifconfig "$TUNDEV" 0.0.0.0
		fi
		if [ -n "$INTERNAL_IP6_ADDRESS" ] && [ -z "$INTERNAL_IP6_NETMASK" ]; then
			INTERNAL_IP6_NETMASK="$INTERNAL_IP6_ADDRESS/128"
		fi
		if [ -n "$INTERNAL_IP6_NETMASK" ]; then
			ifconfig "$TUNDEV" inet6 del $INTERNAL_IP6_NETMASK
		fi
	fi

	destroy_tun_device
}

#### Main

if [ -z "$reason" ]; then
	echo "this script must be called from vpnc" 1>&2
	exit 1
fi

case "$reason" in
	pre-init)
		run_hooks pre-init
		do_pre_init
		;;
	connect)
		run_hooks connect
		do_connect
		run_hooks post-connect
		;;
	disconnect)
		run_hooks disconnect
		do_disconnect
		run_hooks post-disconnect
		;;
	attempt-reconnect)
		# Invoked before each attempt to re-establish the session.
		# If the underlying physical connection changed, we might
		# be left with a route to the VPN server through the VPN
		# itself, which would need to be fixed.
		run_hooks attempt-reconnect
		;;
	reconnect)
		# After successfully re-establishing the session.
		run_hooks reconnect
		;;
	*)
		echo "unknown reason '$reason'. Maybe vpnc-script is out of date" 1>&2
		exit 1
		;;
esac

exit 0