#!/sbin/runscript
# Copyright 2014 Nicholas Vinson
# Copyright 1999-2014 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

extra_commands="clear list panic save"
extra_started_commands="reload"

depend() {
    need localmount #434774
    before net
}

checkkernel() {
    if ! nft list tables >/dev/null 2>&1; then
        eerror "Your kernel lacks nftables support, please load"
        eerror "appropriate modules and try again."
        return 1
    fi
    return 0
}

checkconfig() {
    if [ ! -f ${NFTABLES_SAVE} ]; then
        eerror "Not starting nftables.  First create some rules then run:"
        eerror "rc-service nftables save"
        return 1
    fi
    return 0
}

getfamilies() {
    local families
    for l3f in ip arp ip6 bridge inet; do
        if nft list tables ${l3f} > /dev/null 2>&1; then
            families="${families}${l3f} "
        fi
    done
    echo ${families}
}

clearNFT() {
    local l3f line table chain

    for l3f in $(getfamilies); do
        nft list tables ${l3f} | while read line; do
            table=$(echo ${line} | sed "s/table[ \t]*//")
            nft flush table ${l3f} ${table}
            nft list table ${l3f} ${table} | while read l; do
                chain=$(echo $l | grep -o 'chain [^[:space:]]\+' |\
                        cut -d ' ' -f2)
                if [ -n "${chain}" ]; then
                    nft flush chain ${l3f} ${table} ${chain}
                    nft delete chain ${l3f} ${table} ${chain}
                fi
            done
            nft delete table ${l3f} ${table}
        done
    done
}

addpanictable() {
    local l3f=$1
    nft add table ${l3f} panic
    nft add chain ${l3f} panic input \{ type filter hook input priority 0\; \}
    nft add chain ${l3f} panic output \{ type filter hook output priority 0\; \}
    nft add chain ${l3f} panic forward \{ type filter hook forward priority 0\; \}
    nft add rule ${l3f} panic input drop
    nft add rule ${l3f} panic output drop
    nft add rule ${l3f} panic forward drop
}

start_pre() {
    checkkernel || return 1
    checkconfig || return 1
	return 0
}

start() {
    ebegin "Loading nftables state and starting firewall"
    clearNFT
    nft -f ${NFTABLES_SAVE}
    eend $?
}

stop() {
    if yesno ${SAVE_ON_STOP:-yes}; then
        save || return 1
    fi

    ebegin "Stopping firewall"
    clearNFT
    eend $?
}

reload() {
    checkkernel || return 1
    # checkrules || return 1
    ebegin "Flushing firewall"
    clearNFT

    start
}

clear() {
    clearNFT
}

list() {
    local l3f

    for l3f in $(getfamilies); do
        nft list tables ${l3f} | while read line; do
            line=$(echo ${line} | sed "s/table/table ${l3f}/")
            echo "$(nft list ${line})"
        done
    done
}

save() {
    ebegin "Saving nftables state"
    checkpath -q -d "$(dirname "${NFTABLES_SAVE}")"
    checkpath -q -m 0600 -f "${NFTABLES_SAVE}"

    local l3f line tmp_save="${NFTABLES_SAVE}.tmp"

    touch "${tmp_save}"
    for l3f in $(getfamilies); do
        nft list tables ${l3f} | while read line; do
            line=$(echo ${line} | sed "s/table/table ${l3f}/")
            # The below substitution fixes an issue where nft -n output may not
            # always be parsable by nft -f.  For example, nft -n might print
            #
            #     ip6 saddr ::1 ip6 daddr ::1 counter packets 0 bytes 0 accept
            #
            # but nft -f refuses to parse that string with error:
            #
            #     In file included from internal:0:0-0:
            #     /var/lib/nftables/rules-save:1:1-2: Error: Could not process rule:
            #     Invalid argument
            #     table ip6 filter {
            #     ^^
            echo "$(nft ${SAVE_OPTIONS} list ${line} |\
                    sed 's/\(::[0-9a-fA-F]\+\)\([^/]\)/\1\/128\2/g')" >> "${tmp_save}"
        done
    done
    mv "${tmp_save}" "${NFTABLES_SAVE}"
}

panic() {
    checkkernel || return 1
    if service_started ${RC_SVCNAME}; then
        rc-service ${RC_SVCNAME} stop
    fi

    ebegin "Dropping all packets"
    clearNFT

    local l3f
    for l3f in $(getfamilies); do
        case ${l3f} in
            ip) addpanictable ${l3f} ;;
            ip6) addpanictable ${l3f} ;;
        esac
    done
}