#!/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/>.       #
#                                                                             #
###############################################################################

VPN_SECURITY_POLICIES_CONFIG_SETTINGS="CIPHER COMPRESSION GROUP_TYPE INTEGRITY KEY_EXCHANGE LIFETIME PFS"
VPN_SECURITY_POLICIES_READONLY="system"

VPN_DEFAULT_SECURITY_POLICY="system"

VPN_SUPPORTED_CIPHERS="AES192 AES256 AES512"
VPN_SUPPORTED_INTEGRITY="SHA512 SHA256 SHA128"
VPN_SUPPORTED_GROUP_TYPES="MODP8192 MODP4096"

# This functions checks if a policy is readonly
# returns true when yes and false when no
vpn_security_policies_check_readonly() {
	if isoneof name ${VPN_SECURITY_POLICIES_READONLY}; then
		return ${EXIT_TRUE}
	else
		return ${EXIT_FALSE}
	fi
}

# This function writes all values to a via ${name} specificated vpn security policy configuration file
vpn_security_policies_write_config() {
	assert [ $# -ge 1 ]

	local name="${1}"

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

	if vpn_security_policies_check_readonly "${name}"; then
		log ERROR "The ${name} vpn security policy cannot be changed."
		return ${EXIT_ERROR}
	fi

	local path="$(vpn_security_policies_path "${name}")"
	if [ ! -w ${path} ]; then
		log ERROR "${path} is not writeable"
		return ${EXIT_ERROR}
	fi

	if ! settings_write "${path}" ${VPN_SECURITY_POLICIES_CONFIG_SETTINGS}; then
		log ERROR "Could not write configuration settings for vpn security policy ${name}"
		return ${EXIT_ERROR}
	fi

	# TODO everytime we successfully write a config we should call some trigger to take the changes into effect
}

# This funtion writes the value for one key to a via ${name} specificated vpn security policy configuration file
vpn_security_policies_write_config_key() {
	assert [ $# -ge 3 ]

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

	local value="$@"

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

	log DEBUG "Set '${key}' to new value '${value}' in vpn security policy ${name}"

	local ${VPN_SECURITY_POLICIES_CONFIG_SETTINGS}

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

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

	if ! vpn_security_policies_write_config "${name}"; 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.
vpn_security_policies_read_config() {
	assert [ $# -ge 1 ]

	local name="${1}"
	shift 1

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


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

	local path="$(vpn_security_policies_path ${name})"

	if ! settings_read "${path}" ${args}; then
		log ERROR "Could not read settings for vpn security policy ${name}"
		return ${EXIT_ERROR}
	fi
}

# Returns the path to a the configuration fora given name
vpn_security_policies_path() {
	assert [ $# -eq 1 ]

	local name=${1}

	if vpn_security_policies_check_readonly "${name}"; then
		echo "${NETWORK_SHARE_DIR}/vpn/security-policies/${name}"
	else
		echo "${NETWORK_CONFIG_DIR}/vpn/security-policies/${name}"
	fi
}

# Print the content of a vpn security policy configuration file in a nice way
vpn_security_policies_show() {
	assert [ $# -eq 1 ]

	local name=${1}

	local ${VPN_SECURITY_POLICIES_CONFIG_SETTINGS}
	if ! vpn_security_policies_read_config ${name}; then
		return ${EXIT_ERROR}
	fi

	cli_print_fmt1 0 "Security Policy: ${name}"
	cli_space

	# This could be done in a loop but a loop is much more complicated
	# because we print 'Group Types' but the variable is named 'GROUP_TYPES'
	cli_print_fmt1 1 "Ciphers:"
	cli_print_fmt1 2 "${CIPHER}"
	cli_space

	cli_print_fmt1 1 "Integrity:"
	cli_print_fmt1 2 "${INTEGRITY}"
	cli_space

	cli_print_fmt1 1 "Group Types:"
	cli_print_fmt1 2 "${GROUP_TYPE}"
	cli_space

	cli_print_fmt1 1 "Key Exchange:" "${KEY_EXCHANGE}"

	# Key Lifetime
	if isinteger LIFETIME && [ ${LIFETIME} -gt 0 ]; then
		cli_print_fmt1 1 "Key Lifetime:" "$(format_time ${LIFETIME})"
	else
		log ERROR "The value for Key Lifetime is not a valid integer greater zero."
	fi

	# PFS
	if enabled PFS; then
		cli_print_fmt1 1 "Perfect Forward Secrecy:" "enabled"
	else
		cli_print_fmt1 1 "Perfect Forward Secrecy:" "disabled"
	fi
	cli_space

	# Compression
	if enabled COMPRESSION; then
		cli_print_fmt1 1 "Compression:" "enabled"
	else
		cli_print_fmt1 1 "Compression:" "disabled"
	fi
	cli_space
}

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

	local name=${1}

	local path=$(vpn_security_policies_path "${name}")

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


# This function parses the parameters for the 'cipher' command
vpn_security_policies_cipher(){
	local name=${1}
	shift

	if [ $# -eq 0 ]; then
		log ERROR "You must pass at least one value after cipher"
		return ${EXIT_ERROR}
	fi

	local CIPHER
	if ! vpn_security_policies_read_config ${name} "CIPHER"; then
		return ${EXIT_ERROR}
	fi

	# Remove duplicated entries to proceed the list safely
	CIPHER="$(list_unique ${CIPHER})"

	while [ $# -gt 0 ]; do
		case "${1}" in
			-*)
				value=${1#-}
				# Check if the cipher is in the list of ciphers and
				# check if the list has after removing this cipher at least one valid value
				if list_match ${value} ${CIPHER}; then
					list_remove CIPHER ${value}
				else
					# We do not break here because this error does not break the processing of the next maybe valid values.
					log ERROR "Can not remove ${value} from the list of Ciphers because ${value} is not in the list."
				fi
				;;
			+*)
				value=${1#+}
				# Check if the Ciphers is in the list of supported ciphers.
				if ! isoneof value ${VPN_SUPPORTED_CIPHERS}; then
					# We do not break here because this error does not break the processing of the next maybe valid values.
					log ERROR "${value} is not a supported cipher and can thats why not added to the list of ciphers."
				else
					if list_match ${value} ${CIPHER}; then
						log WARNING "${value} is already in the list of ciphers of this policy."
					else
						list_append CIPHER ${value}
					fi
				fi
				;;
		esac
		shift
	done

	# Check if the list contain at least one valid cipher
	if [ $(list_length ${CIPHER}) -ge 1 ]; then
		if ! vpn_security_policies_write_config_key ${name} "CIPHER" ${CIPHER}; then
			log ERROR "The changes for the vpn security policy ${name} could not be written."
		fi
	else
		log ERROR "After proceding all ciphers the list is empty and thats why no changes are written."
		return ${EXIT_ERROR}
	fi
}

# This function parses the parameters for the 'compression' command
vpn_security_policies_compression(){
	local name=${1}
	local value=${2}

	# Check if we get only one argument after compression <name>
	if [ ! $# -eq 2 ]; then
		log ERROR "The number of arguments do not match. Only one argument after compression is allowed."
		return ${EXIT_ERROR}
	fi

	if ! isbool value; then
		# We suggest only two values to avoid overburding the user.
		log ERROR "Invalid Argument ${value}"
		return ${EXIT_ERROR}
	fi

	vpn_security_policies_write_config_key "${name}" "COMPRESSION" "${value}"
}

# This function parses the parameters for the 'group-type' command
vpn_security_policies_group_type(){
	local name=${1}
	shift

	if [ $# -eq 0 ]; then
		log ERROR "You must pass at least one value after group-type"
		return ${EXIT_ERROR}
	fi

	local GROUP_TYPE
	if ! vpn_security_policies_read_config ${name} "GROUP_TYPE"; then
		return ${EXIT_ERROR}
	fi

	# Remove duplicated entries to proceed the list safely
	GROUP_TYPE="$(list_unique ${GROUP_TYPE})"

	while [ $# -gt 0 ]; do
		case "${1}" in
			-*)
				value=${1#-}
				# Check if the group type is in the list of group types and
				# check if the list has after removing this group type at leatst one valid value
				if list_match ${value} ${GROUP_TYPE}; then
					list_remove GROUP_TYPE ${value}
				else
					# We do not break here because this error does not break the processing of the next maybe valid values.
					log ERROR "Can not remove ${value} from the list of group types because ${value} is not in the list."
				fi
				;;
			+*)
				value=${1#+}
				# Check if the group type is in the list of supported group types.
				if ! isoneof value ${VPN_SUPPORTED_GROUP_TYPES}; then
					# We do not break here because the processing of other maybe valid values are indepent from this error.
					log ERROR "${value} is not a supported group type and can thats why not added to the list of group types."
				else
					if list_match ${value} ${GROUP_TYPE}; then
						log WARNING "${value} is already in the list of group-types of this policy."
					else
						list_append GROUP_TYPE ${value}
					fi
				fi
				;;
		esac
		shift
	done

	# Check if the list contain at least one valid group-type
	if [ $(list_length ${GROUP_TYPE}) -ge 1 ]; then
		if ! vpn_security_policies_write_config_key ${name} "GROUP_TYPE" ${GROUP_TYPE}; then
			log ERROR "The changes for the vpn security policy ${name} could not be written."
		fi
	else
		log ERROR "After proceding all group types the list is empty and thats why no changes are written."
		return ${EXIT_ERROR}
	fi
}

# This function parses the parameters for the 'integrity' command
vpn_security_policies_integrity(){
	local name=${1}
	shift

	if [ $# -eq 0 ]; then
		log ERROR "You must pass at least one value after integrity."
		return ${EXIT_ERROR}
	fi

	local INTEGRITY
	if ! vpn_security_policies_read_config ${name} "INTEGRITY"; then
		return ${EXIT_ERROR}
	fi

	# Remove duplicated entries to proceed the list safely
	INTEGRITY="$(list_unique ${INTEGRITY})"

	while [ $# -gt 0 ]; do
		case "${1}" in
			-*)
				value=${1#-}
				# Check if the integrity hash is in the list of integrity hashes and
				# check if the list has after removing this  integrity hash at least one valid value
				if list_match ${value} ${INTEGRITY}; then
					list_remove INTEGRITY ${value}
				else
					# We do not break here because the processing of other maybe valid values are indepent from this error.
					log ERROR "Can not remove ${value} from the list of integrity hashes because ${value} is not in the list."
				fi
				;;
			+*)
				value=${1#+}
				# Check if the Ciphers is in the list of supported integrity hashes.
				if ! isoneof value ${VPN_SUPPORTED_INTEGRITY}; then
					# We do not break here because the processing of other maybe valid values are indepent from this error.
					log ERROR "${value} is not a supported integrity hash and can thats why not added to the list of integrity hashes."
				else
					if list_match ${value} ${INTEGRITY}; then
						log WARNING "${value} is already in the list of integrety hashes of this policy."
					else
						list_append INTEGRITY ${value}
					fi
				fi
				;;
		esac
		shift
	done

	# Check if the list contain at least one valid group-type
	if [ $(list_length ${INTEGRITY}) -ge 1 ]; then
		if ! vpn_security_policies_write_config_key ${name} "INTEGRITY" ${INTEGRITY}; then
			log ERROR "The changes for the vpn security policy ${name} could not be written."
		fi
	else
		log ERROR "After proceding all integrity hashes the list is empty and thats why no changes are written."
		return ${EXIT_ERROR}
	fi
}

# This function parses the parameters for the 'key-exchange' command
vpn_security_policies_key_exchange() {
	local name=${1}
	local value=${2}

	# Check if we get only one argument after key-exchange <name>
	if [ ! $# -eq 2 ]; then
		log ERROR "The number of arguments do not match. Only argument after key-exchange is allowed."
		return ${EXIT_ERROR}
	fi

	if ! isoneof value "ikev1" "ikev2" "IKEV1" "IKEV2"; then
		log ERROR "Invalid Argument ${value}"
		return ${EXIT_ERROR}
	fi

	vpn_security_policies_write_config_key "${name}" "KEY_EXCHANGE" "${value,,}"
}

# This function parses the parameters for the 'lifetime' command.
vpn_security_policies_lifetime(){
	local name=${1}
	shift

	local value=$@

	# Check if we get only one argument after lifetime <name>
	if [ ! $# -ge 1 ]; then
		log ERROR "The number of arguments do not match you must provide at least one integer value or a valid time with the format  <hours>h <minutes>m <seconds>s"
		return ${EXIT_ERROR}
	fi

	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

	vpn_security_policies_write_config_key "${name}" "LIFETIME" "${value}"
}

# This function parses the parameters for the 'pfs' command
vpn_security_policies_pfs(){
	local name=${1}
	local value=${2}

	# Check if we get only one argument after pfs <name>
	if [ ! $# -eq 2 ]; then
		log ERROR "The number of arguments do not match. Only argument after pfs is allowed."
		return ${EXIT_ERROR}
	fi

	if [ ! $# -eq 2 ] || ! isbool value; then
		# We suggest only two values to avoid overburding the user.
		log ERROR "Invalid Argument ${value}"
		return ${EXIT_ERROR}
	fi

	vpn_security_policies_write_config_key "${name}" "PFS" "${value}"
}

# This function checks if a vpn security policy name is valid
# Allowed are only A-Za-z0-9
vpn_security_policies_check_name() {
	assert [ $# -eq 1 ]

	local name=${1}

	[[ ${name} =~ [^[:alnum:]$] ]]
}

# Function that creates based on the paramters one ore more new vpn security policies
vpn_security_policies_new() {
	if [ $# -gt 1 ]; then
		error "Too many arguments"
		return ${EXIT_ERROR}
	fi

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

	# Check for duplicates
	if vpn_security_policy_exists "${name}"; then
		error "The VPN security policy with name ${name} already exists"
		return ${EXIT_ERROR}
	fi

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

	# Check if we have a read-only policy with the same name
	if vpn_security_policies_check_readonly "${name}"; then
		error "The VPN security policy ${name} is read-only"
		return ${EXIT_ERROR}
	fi

	# Check if our source policy exists
	if ! vpn_security_policy_exists "${VPN_DEFAULT_SECURITY_POLICY}"; then
		error "Default VPN Security Policy '${VPN_DEFAULT_SECURITY_POLICY}' does not exist"
		return ${EXIT_ERROR}
	fi

	log DEBUG "Creating VPN Security Policy ${name}"

	if copy "$(vpn_security_policies_path "${VPN_DEFAULT_SECURITY_POLICY}")"
			"$(vpn_security_policies_path ${name})"; then
		log INFO "VPN Security Policy ${name} successfully created"
	else
		log ERROR "Could not create VPN Security Policy ${name}"
		return ${EXIT_ERROR}
	fi

	# Show the newly created policy
	vpn_security_policies_show "${name}"
}

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

		if vpn_security_policies_check_readonly ${name}; then
			log ERROR "The vpn security policy ${name} cannot be deleted."
			continue
		fi

		log DEBUG "Deleting vpn security policy ${name}"
		settings_remove $(vpn_security_policies_path ${name})
	done
}