#!/bin/sh
# Copyright 1999-2012 Gentoo Foundation
# Distributed under the terms of the GNU General Public Licens

VERSION="0.3.0"

has() {
	local desired=$1 x
	shift
	for x in "$@"; do
		[ "$desired" = "$x" ] && return 0;
	done
	return 1
}

find_available_node() {
	local val=$(ip addr | grep -i '.*: qtap' | cut -d: -f2)
	local pos=0
	while has qtap${pos} ${val##*()}; do
		pos=$(( $pos + 1 ))
	done
	echo qtap${pos}
}

create_node() {
	local qtap="$1"
	shift
	tunctl -b -t "${qtap}" "$@" > /dev/null || die "tunctl failed"
	brctl addif br0 "${qtap}" || die "brctl failed"
	ip link set "${qtap}" up || die "ip link set ${qtap} failed"
	ip link set "${qtap}" promisc on || die "ip link set ${qtap} promiscuos mode failed"
}

destroy_node() {
	issue=
	ip link set ${1} down || { echo "ip link set ${1} down failed";issue=1; }
	brctl delif br0 ${1} || { echo "brctl failed";issue=2; }
	tunctl -d ${1} > /dev/null || { echo "tunctl failed";issue=3;}
	[ -n "${issue}" ] && exit $(( $issue ))
}

die() {
	echo "$@" >&2
	exit 1
}

usage() {
	echo "commands available:"
	echo "create-specific qtap-name [ -u user ] [ -g group ]"
	echo "create [ -u user ] [ -g group ]"
	echo "destroy qtap-name"
	echo "version"
	echo
}

usage_die() {
	usage
	die "$@"
}

show_version() {
	echo "qtap-manipulate version: ${VERSION}"
}

create_user=
create_group=

parse_create_options() {
	while [ $# -ne 0 ]; do
		local x="$1"
		case "$x" in
			-u=*)
				shift
				set -- "-u" "${x#-u=}" "$@"
				;&
			-u)
				shift
				[ -z "$1" ] && die "-u requires an argument"
				create_user="$1"
				shift
				;;
			-g=*)
				shift
				set -- "-g" "${x#-u=}" "$@"
				;&
			-g)
				shift
				[ -z "$1" ] && die "-g requires an argument"
				create_group="$2"
				shift
				;;
			*)
				die "unknown option $1"
		esac
	done
}

output_qtap=false
case "$1" in
	destroy)
		shift
		[ $# -eq 0 ] && usage_die "destroy requires a second argument"
		[ $# -gt 1 ] && usage_die "no idea what to do with args: $@"
		destroy_node "$1"
		;;
	create)
		output_qtap=true
		qtap=$(find_available_node)
		[ -z "$qtap" ] && die "failed to find a qtap node to use"
		shift
		set -- create_specific "${qtap}" "$@"
		;&
	create_specific)
		shift
		qtap="$1"; shift
		parse_create_options "$@"
		create_node "$qtap"
		$output_qtap && echo "$qtap"
		;;
	version)
		show_version
		;;
	*)
		usage_die "Unknown command $1"
		;;
esac
exit 0