#!/bin/bash
#
#  Copyright (c) 2017, The OpenThread Authors.
#  All rights reserved.
#
#  Redistribution and use in source and binary forms, with or without
#  modification, are permitted provided that the following conditions are met:
#  1. Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
#  2. Redistributions in binary form must reproduce the above copyright
#     notice, this list of conditions and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#  3. Neither the name of the copyright holder nor the
#     names of its contributors may be used to endorse or promote products
#     derived from this software without specific prior written permission.
#
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#  POSSIBILITY OF SUCH DAMAGE.
#
#   Description:
#       This script manipulates nat64 configuration.
#

NAT64_SERVICE="${NAT64_SERVICE:-tayga}"
TAYGA_DEFAULT=/etc/default/tayga
TAYGA_CONF=/etc/tayga.conf
TAYGA_IPV4_ADDR=192.168.255.1
TAYGA_IPV6_ADDR=fdaa:bb:1::1
TAYGA_TUN_V6_ADDR=fdaa:bb:1::2
NAT64_PREFIX=64:ff9b::/96
DYNAMIC_POOL="${NAT64_DYNAMIC_POOL:-192.168.255.0/24}"
NAT44_SERVICE=/etc/init.d/otbr-nat44
WLAN_IFNAMES="${INFRA_IF_NAME:-eth0}"

# Currently solution was verified only on raspbian and ubuntu.
#
#without NAT64 || test $PLATFORM = ubuntu || test $PLATFORM = raspbian || die "nat64 is not tested under $PLATFORM."

tayga_install()
{
    test -f $TAYGA_DEFAULT -a -f $TAYGA_CONF || die 'Cannot find tayga configuration file!'
    sudo sed -i 's/^RUN="no"/RUN="yes"/' $TAYGA_DEFAULT
    sudo sed -i 's/^IPV4_TUN_ADDR=""/IPV4_TUN_ADDR="'$TAYGA_IPV4_ADDR'"/' $TAYGA_DEFAULT
    sudo sed -i 's/^IPV6_TUN_ADDR=""/IPV6_TUN_ADDR="'$TAYGA_TUN_V6_ADDR'"/' $TAYGA_DEFAULT
    sudo sed -i 's/^prefix /##prefix /' $TAYGA_CONF
    sudo sed -i '/^##prefix /a prefix '$NAT64_PREFIX $TAYGA_CONF
    sudo sed -i '/^#ipv6-addr/a ipv6-addr '$TAYGA_IPV6_ADDR $TAYGA_CONF
    sudo sed -i 's/^dynamic-pool /##dynamic-pool /' $TAYGA_CONF
    sudo sed -i '/^##dynamic-pool /a dynamic-pool '"$DYNAMIC_POOL" $TAYGA_CONF

    if have systemctl; then
        sudo systemctl restart tayga || die 'Unable to restart taga service!'
        sudo systemctl enable tayga || die 'Unable to enable taga service!'
    fi
}

tayga_uninstall()
{
    sudo sed -i 's/^RUN="yes"/RUN="no"/' $TAYGA_DEFAULT
    sudo sed -i 's/^IPV4_TUN_ADDR="'$TAYGA_IPV4_ADDR'"/IPV4_TUN_ADDR=""/' $TAYGA_DEFAULT
    sudo sed -i '/^prefix /d' $TAYGA_CONF
    if grep "##prefix " $TAYGA_CONF; then
        sudo sed -i 's/^##prefix /prefix /' $TAYGA_CONF
    else
        sudo sed -i 's/^# prefix /prefix /' $TAYGA_CONF
    fi
    sudo sed -i '/^ipv6-addr '$TAYGA_IPV6_ADDR'/d' $TAYGA_CONF
    if grep "##dynamic-pool " $TAYGA_CONF; then
        sudo sed -i '/^dynamic-pool /d' $TAYGA_CONF
        sudo sed -i 's/^##dynamic-pool /dynamic-pool /' $TAYGA_CONF
    fi
}

tayga_start()
{
    if with DOCKER; then
        service tayga start || die 'Failed to start tayga'
    elif have systemctl; then
        sudo systemctl start tayga || die 'Failed to start tayga!'
        sudo systemctl enable tayga || die 'Failed to enable tayga!'
    fi
}

tayga_stop()
{
    if with DOCKER; then
        service tayga stop || true
    elif have systemctl; then
        sudo systemctl stop tayga || true
    fi
}

# Although Tayga also configures a NAT44 iptables route, this NAT44 service is used with Tayga
# due to some history reason. It might be removed when native NAT64 service is ready.
nat44_install()
{
    sudo tee $NAT44_SERVICE <<EOF
#! /bin/sh
#
#  Copyright (c) 2017, The OpenThread Authors.
#  All rights reserved.
#
#  Redistribution and use in source and binary forms, with or without
#  modification, are permitted provided that the following conditions are met:
#  1. Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
#  2. Redistributions in binary form must reproduce the above copyright
#     notice, this list of conditions and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#  3. Neither the name of the copyright holder nor the
#     names of its contributors may be used to endorse or promote products
#     derived from this software without specific prior written permission.
#
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#  POSSIBILITY OF SUCH DAMAGE.
#
### BEGIN INIT INFO
# Provides:          otbr-nat44
# Required-Start:    tayga
# Required-Stop:
# Should-Start:
# Should-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:
# Short-Description: iptables NAT44
# Description:       NAT44 is require for OpenThread border router
#                    to connect to arbitrary IPv4 endpoints.
### END INIT INFO

. /lib/lsb/init-functions
. /lib/init/vars.sh

case "\$1" in
    start)
EOF
    for IFNAME in $WLAN_IFNAMES; do
        echo "      iptables -t nat -A POSTROUTING -o $IFNAME -j MASQUERADE" | sudo tee -a $NAT44_SERVICE
    done
    sudo tee -a $NAT44_SERVICE <<EOF
        ;;
    restart|reload|force-reload)
        echo "Error: argument '\$1' not supported" >&2
        exit 3
        ;;
    stop|status)
        # No-op
        ;;
    *)
        echo "Usage: \$0 start|stop" >&2
        exit 3
        ;;
esac
EOF
    sudo chmod a+x $NAT44_SERVICE
    if have systemctl; then
        sudo systemctl enable otbr-nat44 || die 'Unable to enable nat44 service!'
    fi
}

nat44_uninstall()
{
    if have systemctl; then
        sudo systemctl disable otbr-nat44 || true
    fi

    # systemctl disable doesn't remove sym-links
    if have update-rc.d; then
        sudo update-rc.d otbr-nat44 remove || true
    fi
    test ! -f $NAT44_SERVICE || sudo rm $NAT44_SERVICE
}

nat44_start()
{
    if [ "$NAT64_SERVICE" = tayga ] && have systemctl; then
        sudo systemctl start otbr-nat44 || die 'Failed to start NAT44!'
    else
        sudo iptables -t nat -A POSTROUTING -s "$DYNAMIC_POOL" -j MASQUERADE || die 'Failed to start NAT44!'
    fi
}

nat44_stop()
{
    if [ "$NAT64_SERVICE" = tayga ] && have systemctl; then
        sudo systemctl stop otbr-nat44 || true
    else
        sudo iptables -t nat -D POSTROUTING -s "$DYNAMIC_POOL" -j MASQUERADE || true
    fi
}

nat64_install()
{
    with NAT64 || return 0

    if [ "$NAT64_SERVICE" = tayga ]; then
        tayga_install
        nat44_install
    fi
}

nat64_uninstall()
{
    with NAT64 || return 0

    nat64_stop

    if [ "$NAT64_SERVICE" = tayga ]; then
        tayga_uninstall
        nat44_uninstall
    fi
}

nat64_start()
{
    with NAT64 || return 0

    if [ "$NAT64_SERVICE" = tayga ]; then
        tayga_start
    fi

    nat44_start
}

nat64_stop()
{
    with NAT64 || return 0

    if [ "$NAT64_SERVICE" = tayga ]; then
        tayga_stop
    fi

    nat44_stop
}