#!/bin/bash
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2010  Michael Tremer & Christian Schmidt                      #
#                                                                             #
# 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 3 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, see <http://www.gnu.org/licenses/>.       #
#                                                                             #
###############################################################################

function ipv6_device_autoconf_enable() {
	local device=${1}

	if ! device_exists ${device}; then
		error "Device '${device}' does not exist."
		return ${EXIT_ERROR}
	fi

	echo 1 > /proc/sys/net/ipv6/conf/${device}/autoconf
}

function ipv6_device_autoconf_disable() {
	local device=${1}

	if ! device_exists ${device}; then
		error "Device '${device}' does not exist."
		return ${EXIT_ERROR}
	fi

	echo 0 > /proc/sys/net/ipv6/conf/${device}/autoconf
}

function ipv6_is_valid() {
	local address=${1}

	# Check length
	[ ${#address} -gt 39 ] && return ${EXIT_ERROR}

	# XXX find :: twice?
	# XXX check for documentation prefix?

	# Check for bad characters
	local char
	for char in 0 1 2 3 4 5 6 7 8 9 a b c d e f :; do
		address=${address//${char}/}
	done
	[ -n "${address}" ] && return ${EXIT_ERROR}

	return ${EXIT_OK}
}

function ipv6_implode() {
	local address=${1}

	if ! ipv6_is_valid ${address}; then
		error "IPv6 address is invalid: ${address}"
		return ${EXIT_ERROR}
	fi

	# Make proper address in exploded format
	address=$(ipv6_explode ${address})

	local block
	local char
	local i

	local address_new
	local block_new

	for block in ${address//:/\ }; do
		block_new=
		for i in $(seq 0 ${#block}); do
			char="${block:${i}:1}"

			[ -z "${char}" ] && continue

			if [ -z "${block_new}" ] && [ "${char}" = "0" ]; then
				continue
			fi

			block_new="${block_new}${char}"
		done

		[ -z "${block_new}" ] && block_new="0"

		address_new="${address_new}:${block_new}"
	done

	# Cut first colon (:)
	address="${address_new:1:${#address_new}}"

	local match
	local matches=()
	local pattern
	local pos_start
	local pos_next
	for pos_start in $(seq 0 ${#address}); do
		matches["${pos_start}"]=0

		for pos_next in $(seq ${pos_start} 2 ${#address}); do
			case "${pos_start}" in
				0)
					match="${address:${pos_next}:2}"
					pattern="0:"
					;;
				*)
					match="${address:${pos_next}:2}"
					pattern=":0"
					;;
			esac

			[ -z "${match}" ] && continue

			if [ "${match}" = "${pattern}" ]; then
				matches[${pos_start}]=$(( matches[${pos_start}] + 1))
			else
				break
			fi
		done
	done

	local pos_best
	local pos_best_val=0
	for i in $(seq 0 ${#matches[@]}); do
		[ -z "${matches[${i}]}" ] && continue

		if [ ${matches[${i}]} -gt ${pos_best_val} ]; then
			pos_best=${i}
			pos_best_val=${matches[${i}]}
		fi
	done

	if [ -n "${pos_best}" ]; then
		address_new="${address:0:${pos_best}}::"

		local pos_end=$(( ${pos_best_val} * 2 + ${pos_best} + 1))
		
		if [ "${pos_best}" = "0" ]; then
			pos_end=$(( ${pos_end} - 1 ))
		fi

		address="${address_new}${address:${pos_end}:${#address}}"
	fi

	assert ipv6_is_valid ${address}

	echo "${address}"
}

function ipv6_explode() {
	local address=${1}

	if [ ${#address} -eq 39 ]; then
		echo "${address}"
		return ${EXIT_OK}	
	fi

	address=${address//::/:X:}

	local block
	local block_count=0
	local block_id
	local block_max=8
	local blocks=()

	for block in ${address//:/\ }; do
		blocks[${block_count}]=${block}
		
		block_count=$(( ${block_count} + 1 ))
	done

	if [ ${#blocks[@]} -lt ${block_max} ]; then
		for block_id in $(seq ${#blocks[@]} -1 0); do
			block=${blocks[${block_id}]}

			[ -z "${block}" ] && continue

			if [ "${block}" = "X" ]; then
				blocks[${block_id}]="0000"
				break
			fi

			blocks[$(( ${block_max} - ${block_count} + ${block_id} ))]=${block}
			blocks[${block_id}]="0000"
		done
	fi

	for block_id in $(seq 0 ${#blocks[@]}); do
		block=${blocks[${block_id}]}

		[ -z "${block}" ] && block="0000"

		while [ "${#block}" -lt 4 ]; do
			block="0${block}"
		done

		blocks[${block_id}]=${block}
	done

	address=
	for block in ${blocks[@]}; do
		address="${address}:${block}"
	done
	address=${address:1:39}

	assert ipv6_is_valid ${address}

	echo "${address}"
}

function ipv6_hash() {
	local address=${1}

	# Explode address
	address=$(ipv6_explode ${address})

	echo "${address//:/}"
}