#!/bin/bash
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2017  IPFire Network Development Team                         #
#                                                                             #
# 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/>.       #
#                                                                             #
###############################################################################

IPSEC_CONNECTION_CONFIG_SETTINGS="AUTH_MODE INACTIVITY_TIMEOUT LOCAL_ID LOCAL_PREFIX"
IPSEC_CONNECTION_CONFIG_SETTINGS="${IPSEC_CONNECTION_CONFIG_SETTINGS} MODE PEER PSK"
IPSEC_CONNECTION_CONFIG_SETTINGS="${IPSEC_CONNECTION_CONFIG_SETTINGS} REMOTE_ID REMOTE_PREFIX"
IPSEC_CONNECTION_CONFIG_SETTINGS="${IPSEC_CONNECTION_CONFIG_SETTINGS} SECURITY_POLICY"

# Default values
IPSEC_DEFAULT_MODE="tunnel"
IPSEC_DEFAULT_AUTH_MODE="psk"
IPSEC_DEFAULT_INACTIVITY_TIMEOUT="0"
IPSEC_DEFAULT_SECURITY_POLICY="system"

IPSEC_VALID_MODES="gre-transport tunnel vti"
IPSEC_VALID_AUTH_MODES="PSK psk"

cli_ipsec() {
	local action=${1}
	shift 1

	case "${action}" in
		connection)
			cli_ipsec_connection $@
			;;
		*)
			error "Unrecognized argument: ${action}"
			exit ${EXIT_ERROR}
			;;
	esac
}

cli_ipsec_connection() {
	if ipsec_connection_exists ${1}; then
		local connection=${1}
		local key=${2}
		key=${key//-/_}
		shift 2

		case "${key}" in
			authentication|inactivity-timout|local|mode|peer|remote|security-policy)
				ipsec_connection_${key} ${connection} $@
				;;
			*)
				error "Unrecognized argument: ${key}"
				exit ${EXIT_ERROR}
				;;
		esac
	else
		local action=${1}
		shift

		case "${action}" in
			new)
				ipsec_connection_new $@
				;;
			destroy)
				ipsec_connection_destroy $@
				;;
			""|*)
				if [ -n "${action}" ]; then
					error "Unrecognized argument: '${action}'"
				fi
				exit ${EXIT_ERROR}
				;;
		esac
	fi
}

# This function writes all values to a via ${connection} specificated VPN IPsec configuration file
ipsec_connection_write_config() {
	assert [ $# -ge 1 ]

	local connection="${1}"

	if ! ipsec_connection_exists "${connection}"; then
		log ERROR "No such VPN IPsec connection: ${connection}"
		return ${EXIT_ERROR}
	fi

	local path="$(ipsec_connection_path "${connection}")/settings"

	if ! settings_write "${path}" ${IPSEC_CONNECTION_CONFIG_SETTINGS}; then
		log ERROR "Could not write configuration settings for VPN IPsec connection ${connection}"
		return ${EXIT_ERROR}
	fi

	ipsec_reload ${connection}
}

# This funtion writes the value for one key to a via ${connection} specificated VPN IPsec connection configuration file
ipsec_connection_write_config_key() {
	assert [ $# -ge 3 ]

	local connection=${1}
	local key=${2}
	shift 2

	local value="$@"

	if ! ipsec_connection_exists "${connection}"; then
		log ERROR "No such VPN ipsec connection: ${connection}"
		return ${EXIT_ERROR}
	fi

	log DEBUG "Set '${key}' to new value '${value}' in VPN ipsec connection '${connection}'"

	local ${IPSEC_CONNECTION_CONFIG_SETTINGS}

	# Read the config settings
	if ! ipsec_connection_read_config "${connection}"; then
		return ${EXIT_ERROR}
	fi

	# Set the key to a new value
	assign "${key}" "${value}"

	if ! ipsec_connection_write_config "${connection}"; then
		return ${EXIT_ERROR}
	fi

	return ${EXIT_TRUE}
}

# Reads one or more keys out of a settings file or all if no key is provided.
ipsec_connection_read_config() {
	assert [ $# -ge 1 ]

	local connection="${1}"
	shift 1

	if ! ipsec_connection_exists "${connection}"; then
		log ERROR "No such VPN IPsec connection : ${connection}"
		return ${EXIT_ERROR}
	fi


	local args
	if [ $# -eq 0 ] && [ -n "${IPSEC_CONNECTION_CONFIG_SETTINGS}" ]; then
		list_append args ${IPSEC_CONNECTION_CONFIG_SETTINGS}
	else
		list_append args $@
	fi

	local path="$(ipsec_connection_path "${connection}")/settings"

	if ! settings_read "${path}" ${args}; then
		log ERROR "Could not read settings for VPN IPsec connection ${connection}"
		return ${EXIT_ERROR}
	fi
}

# Returns the path to a the directory for given connection
ipsec_connection_path() {
	assert [ $# -eq 1 ]

	local connection=${1}

	echo "${NETWORK_CONFIG_DIR}/vpn/ipsec/connection/${connection}"
}

# This function checks if a vpn ipsec connection exists
# Returns True when yes and false when not
ipsec_connection_exists() {
	assert [ $# -eq 1 ]

	local connection=${1}

	local path=$(ipsec_connection_path "${connection}")

	[ -d "${path}" ] && return ${EXIT_TRUE} || return ${EXIT_FALSE}
}

# Reloads the connection after config changes
ipsec_reload() {
	return ${EXIT_TRUE}
}

# Handle the cli after authentification
ipsec_connection_authentication() {
	if [ ! $# -gt 1 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi

	local connection=${1}
	local cmd=${2}
	shift 2

	case ${cmd} in
		mode)
			ipsec_connection_authentication_mode "${connection}" $@
			;;
		pre-shared-key)
			ipsec_connection_authentication_psk "${connection}" $@
			;;
		*)
			log ERROR "Unrecognized argument: ${cmd}"
			return ${EXIT_ERROR}
			;;
	esac
}

# Set the authentification mode
ipsec_connection_authentication_mode() {
	if [ ! $# -eq 2 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local mode=${2}

	if ! isoneof mode ${IPSEC_VALID_AUTH_MODES}; then
		log ERROR "Auth mode '${mode}' is invalid"
		return ${EXIT_ERROR}
	fi

	if ! ipsec_connection_write_config_key "${connection}" "AUTH_MODE" ${mode,,}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi
}

# Set the psk
ipsec_connection_authentication_psk() {
	if [ ! $# -eq 2]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local psk=${2}

	# TODO Check if psk is valid 

	if ! ipsec_connection_write_config_key "${connection}" "PSK" ${psk}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi

	return ${EXIT_OK}
}

# Handle the cli after local
ipsec_connection_local() {
	if [ ! $# -ge 2 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi

	local connection=${1}
	local cmd=${2}
	shift 2

	case ${cmd} in
		id)
			ipsec_connection_id "${connection}" "LOCAL" $@
			;;
		prefix)
			ipsec_connection_prefix "${connection}" "LOCAL" $@
			;;
		*)
			log ERROR "Unrecognized argument: ${cmd}"
			return ${EXIT_ERROR}
			;;
	esac

	return ${EXIT_OK}
}

# Set the connection mode
ipsec_connection_mode() {
	if [ ! $# -eq 2]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local mode=${2}

	if ! isoneof mode ${IPSEC_VALID_MODES}; then
		log ERROR "Mode '${mode}' is invalid"
		return ${EXIT_ERROR}
	fi

	if ! ipsec_connection_write_config_key "${connection}" "MODE" ${mode}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi

	return ${EXIT_OK}
}

# Set the peer to connect to
ipsec_connection_peer() {
	if [ ! $# -eq 2]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local peer=${2}

	if ! ipsec_connection_check_peer ${peer}; then
		log ERROR "Peer '${peer}' is invalid"
		return ${EXIT_ERROR}
	fi

	if ! ipsec_connection_write_config_key "${connection}" "PEER" ${peer}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi

	return ${EXIT_OK}
}

#Set the local or remote id
ipsec_connection_id() {
	if [ ! $# -eq 3 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local type=${2}
	local id=${3}

	if ! ipsec_connection_check_id ${id}; then
		log ERROR "Id '${id}' is invalid"
		return ${EXIT_ERROR}
	fi
	
	if ! ipsec_connection_write_config_key "${connection}" "${type}_ID" ${id}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi
	
	return ${EXIT_OK}
}

# Set the local or remote prefix 
ipsec_connection_prefix() {
	if [ ! $# -ge 3 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local type=${2}
	shift 2
	
	local _prefix="${type}_PREFIX"
	local "${_prefix}"
	if ! ipsec_connection_read_config "${connection}" "${_prefix}"; then
		return ${EXIT_ERROR}
	fi

	# Remove duplicated entries to proceed the list safely
	assign "${_prefix}" "$(list_unique ${!_prefix} )"

	local prefixes_added
	local prefixes_removed
	local prefixes_set

	while [ $# -gt 0 ]; do
		local arg="${1}"

		case "${arg}" in
			+*)
				list_append prefixes_added "${arg:1}"
				;;
			-*)
				list_append prefixes_removed "${arg:1}"
				;;
			[A-Fa-f0-9]*)
				list_append prefixes_set "${arg}"
				;;
			*)
				error "Invalid argument: ${arg}"
				return ${EXIT_ERROR}
				;;
		esac
		shift
	done

	# Check if the user is trying a mixed operation
	if ! list_is_empty prefixes_set && (! list_is_empty prefixes_added || ! list_is_empty prefixes_removed); then
		error "You cannot reset the prefix list and add or remove prefixes at the same time"
		return ${EXIT_ERROR}
	fi

	# Set new prefix list
	if ! list_is_empty prefixes_set; then
		# Check if all prefixes are valid
		local prefix
		for prefix in ${prefixes_set}; do
			if ! ip_net_is_valid ${prefix}; then
				error "Unsupported prefix: ${prefix}"
				return ${EXIT_ERROR}
			fi
		done

		assign "${_prefix}" "${prefixes_set}"

	# Perform incremental updates
	else
		local prefix

		# Perform all removals
		for prefix in ${prefixes_removed}; do
			if ! list_remove "${_prefix}" ${prefix}; then
				warning "${prefix} was not on the list and could not be removed"
			fi
		done


		for prefix in ${prefixes_added}; do
			if ip_net_is_valid ${prefix}; then
				if ! list_append_unique "${_prefix}" ${prefix}; then
					warning "${prefix} is already on the prefix list"
				fi
			else
				warning "${prefix} is not a valiv IP net and could not be added"
			fi
		done
	fi

	# Check if the list contain at least one valid prefix
	if list_is_empty ${_prefix}; then
		error "Cannot save an empty prefix list"
		return ${EXIT_ERROR}
	fi

	# Save everything
	if ! ipsec_connection_write_config_key "${connection}" "${_prefix}" ${!_prefix}; then
		log ERROR "Could not write configuration settings"
	fi

	return ${EXIT_OK}
}

# Handle the cli after remote
ipsec_connection_remote() {
	if [ ! $# -ge 2 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi

	local connection=${1}
	local cmd=${2}
	shift 2

	case ${cmd} in
		id)
			ipsec_connection_id "${connection}" "REMOTE" $@
			;;

		prefix)
			ipsec_connection_prefix "${connection}" "REMOTE" $@
			;;
		*)
			log ERROR "Unrecognized argument: ${cmd}"
			return ${EXIT_ERROR}
			;;
	esac

	return ${EXIT_OK}
}

# Set the inactivity timeout
ipsec_connection_inactivity_timeout() {
	if [ ! $# -ge 2 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi

	local connection=${1}
	shift 1
	local value=$@

	if ! isinteger value; then
		value=$(parse_time $@)
		if [ ! $? -eq 0 ]; then
			log ERROR "Parsing the passed time was not sucessful please check the passed values."
			return ${EXIT_ERROR}
		fi
	fi

	if [ ${value} -le 0 ]; then
		log ERROR "The passed time value must be in the sum greater zero seconds."
		return ${EXIT_ERROR}
	fi

	if ! ipsec_connection_write_config_key "${connection}" "INACTIVITY_TIMEOUT" ${value}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi

	return ${EXIT_OK}
}


# Set the security policy to use
ipsec_connection_security_policy() {
	if [ ! $# -eq 2 ]; then
		log ERROR "Not enough arguments"
		return ${EXIT_ERROR}
	fi
	local connection=${1}
	local security_policy=${2}

	if ! vpn_security_policy_exists ${security_policy}; then
		log ERROR "No such vpn security policy '${security_policy}'"
		return ${EXIT_ERROR}
	fi

	if ! ipsec_connection_write_config_key "${connection}" "SECURITY_POLICY" ${security_policy}; then
		log ERROR "Could not write configuration settings"
		return ${EXIT_ERROR}
	fi
}

# Check if a id is valid
ipsec_connection_check_id() {
	assert [ $# -eq 1 ]
	local id=${1}

	if [[ ${id} =~ ^@[[:alnum:]]+$ ]] || ip_is_valid ${id}; then
		return ${EXIT_TRUE}
	else
		return ${EXIT_FALSE}
	fi
}

# Checks if a peer is valid
ipsec_connection_check_peer() {
	assert [ $# -eq 1 ]
	local peer=${1}

	# TODO Accept also FQDNs
	if ip_is_valid ${peer}; then
		return ${EXIT_TRUE}
	else
		return ${EXIT_FALSE}
	fi
}

# This function checks if a VPN IPsec connection name is valid
# Allowed are only A-Za-z0-9
ipsec_connection_check_name() {
	assert [ $# -eq 1 ]

	local connection=${1}

	[[ "${connection}" =~ [^[:alnum:]$] ]]
}

# Function that creates one VPN IPsec connection
ipsec_connection_new() {
	if [ $# -gt 1 ]; then
		error "Too many arguments"
		return ${EXIT_ERROR}
	fi

	local connection="${1}"
	if ! isset connection; then
		error "Please provide a connection name"
		return ${EXIT_ERROR}
	fi

	# Check for duplicates
	if ipsec_connection_exists "${connection}"; then
		error "The VPN IPsec connection ${connection} already exists"
		return ${EXIT_ERROR}
	fi

	# Check if the name of the connection is valid
	if  ipsec_connection_check_name "${connection}"; then
		error "'${connection}' contains illegal characters"
		return ${EXIT_ERROR}
	fi

	log DEBUG "Creating VPN IPsec connection ${connection}"

	if ! mkdir -p $(ipsec_connection_path "${connection}"); then
		log ERROR "Could not create config directory for ${connection}"
		return ${EXIT_ERROR}
	fi

	local ${IPSEC_CONNECTION_CONFIG_SETTINGS}

	MODE=${IPSEC_DEFAULT_MODE}
	AUTH_MODE=${IPSEC_DEFAULT_AUTH_MODE}
	INACTIVITY_TIMEOUT=${IPSEC_DEFAULT_INACTIVITY_TIMEOUT}
	SECURITY_POLICY=${IPSEC_DEFAULT_SECURITY_POLICY}

	if ! ipsec_connection_write_config "${connection}"; then
		log ERROR "Could not write new config file"
		return ${EXIT_ERROR}
	fi
}

# Function that deletes based on the passed parameters one ore more vpn security policies
ipsec_connection_destroy() {
	local connection
	for connection in $@; do
		if ! ipsec_connection_exists "${connection}"; then
			log ERROR "The VPN IPsec connection ${connection} does not exist."
			continue
		fi

		log DEBUG "Deleting VPN IPsec connection ${connection}"
		if ! rm -rf $(ipsec_connection_path "${connection}"); then
			log ERROR "Deleting the VPN IPsec connection ${connection} was not sucessful"
			return ${EXIT_ERROR}
		fi
	done
}