#!/bin/sh
# Based on alpine's tunnel configuration script.
# Copyright (c) 2017 Kaarle Ritvanen
# Copyright (c) 2020 Ariadne Conill (extended for ifupdown-ng)
# Copyright (c) 2021 Maximilian Wilhelm (make sure mode/type is 1st parameter, add more options)

[ -z "$IF_TUNNEL_LOCAL" -a -z "$IF_TUNNEL_LOCAL_DEV" ] && exit 1
[ -z "$IF_TUNNEL_REMOTE" ] && exit 1
[ -z "$IF_TUNNEL_MODE" ] && exit 1

[ -n "$VERBOSE" ] && set -x

yesno() {
        case "$1" in
        yes|1)  echo 1 ;;
        *)      echo 0 ;;
        esac
}

# Figure out address familiy
FAMILY="4"

case "$IF_TUNNEL_MODE" in
vti6|ipip6|ip6*)
	FAMILY="6"
	;;
esac

# Figure out object type - gretap tunnels have to create using ip link
# and therefor require 'type' keyword instead of 'mode'
OBJECT="tunnel"
TYPE_KW="mode"
case "${IF_TUNNEL_MODE}" in
*gretap)
	OBJECT="link"
	TYPE_KW="type"

	# Strip possible "ip6" from tunnel mode
	TUNNEL_MODE="gretap"
	;;

*)
	# Store tunnel type/mode separaltely and unset input variable to exclude it
	# from PARAMS below
	TUNNEL_MODE="$IF_TUNNEL_MODE"
	unset IF_TUNNEL_MODE
	;;
esac


# If 'tunnel-local <IP>' was not given but 'tunnel-local-dev <iface>' is given try
# to figure out the IP of the underlay device (wrt the address family used for this
# tunnel) and use this to set up the tunnel
if [ ${PHASE} = "create" -a ! "${IF_TUNNEL_LOCAL}" -a "${IF_TUNNEL_LOCAL_DEV}" ]; then
	if [ "${FAMILY}" = "4" ]; then
		ip=$(ip -4 -brief addr show dev "${IF_TUNNEL_LOCAL_DEV}" 2>/dev/null | awk '{ print $3 }' | cut -d/ -f1)

	# For IPv6 we try to use a non-temporary address (-> privacy extensions)
	else
		# Get all IPv6 addres configured on $IF_TUNNEL_LOCAL_DEV which are not
		# temporary (due to privacy extensions). We do not filter for "mgmtaddr"
		# "scope global" etc. as we don't want to make further assumptions on
		# whether a user wants to use a link local address configured to this interface.
		#
		# The assumption that a temporary address configured by PE isn't suited
		# to terminate a tunnel should hold in nearly all setups, I hope.
		ip=$(ip -6 addr show dev "${IF_TUNNEL_LOCAL_DEV}" -temporary | grep inet6 | head -n1 | awk '{ print $2 }' | cut -d/ -f1)
	fi

	if [ ! "${ip}" ]; then
		echo "Unable to determine the IPv${FAMILIY} address of tunnel-local-dev ${IF_TUNNEL_LOCAL_DEV}!"
		exit 1
	fi

	unset IF_TUNNEL_LOCAL_DEV
	export IF_TUNNEL_LOCAL="${ip}"
fi


# Handle boolean switches
MORE_PARAMS=""
if [ "${IF_TUNNEL_IGNORE_DF}" ]; then
	if $(yesno "${IF_TUNNEL_IGNORE_DF}"); then
		MORE_PARAMS="ignore-df"
	else
		MORE_PARAMS="noignore-df"
	fi

	unset IF_TUNNEL_IGNORE_DF
fi

if [ "${IF_TUNNEL_PMTUDISC}" ]; then
	if $(yesno "${IF_TUNNEL_PMTUDISC}"); then
		MORE_PARAMS="pmtudisc"
	else
		MORE_PARAMS="nopmtudisc"
	fi

	unset IF_TUNNEL_PMTUDISC
fi


# Mangle residual IF_TUNNEL_* params into single string
PARAMS=$(set | sed -E '
	s/^IF_TUNNEL_([A-Z0-9_]+)=(.+)/\1\n\2/
	ta
	d
	:a
	h
	y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/
	P
	g
	s/.*\n//
	')

[ "$PARAMS" ] || exit 0

case "$PHASE" in
create)
	${MOCK} eval ip -$FAMILY $OBJECT add $IFACE $TYPE_KW $TUNNEL_MODE $PARAMS $MORE_PARAMS
	;;
destroy)
	${MOCK} ip -$FAMILY $OBJECT del $IFACE
	;;
depend)
	echo "${IF_TUNNEL_DEV}" "${IF_TUNNEL_LOCAL_DEV}"
	;;
esac