#!/usr/bin/env bash

# -------------------------------------------------------------------------- #
# Copyright 2002-2021, OpenNebula Project, OpenNebula Systems                #
#                                                                            #
# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
# not use this file except in compliance with the License. You may obtain    #
# a copy of the License at                                                   #
#                                                                            #
# http://www.apache.org/licenses/LICENSE-2.0                                 #
#                                                                            #
# Unless required by applicable law or agreed to in writing, software        #
# distributed under the License is distributed on an "AS IS" BASIS,          #
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
# See the License for the specific language governing permissions and        #
# limitations under the License.                                             #
#--------------------------------------------------------------------------- #

#
# network module implementation
#

is_network_supported()
{
    command -v networkctl >/dev/null

    return $?
}

configure_network()
{
    gen_resolvconf
    gen_network_configuration
}

stop_network()
{
    systemctl stop systemd-networkd.service
}

start_network()
{
    systemctl start systemd-networkd.service

    # Dummy query waits until networkd is running
    networkctl list &>/dev/null || :
}

reload_network()
{
    # TODO: for newer systemd-networkd use
    # networkctl reload && networkctl reconfigure ethX
    # and fallback to service restart only if needed
    systemctl restart systemd-networkd.service

    # Dummy query waits until networkd is running
    networkctl list &>/dev/null || :
}

#
# helper functions
#

# TODO: remove global variables and get rid off exports
#
# to satisfy shellcheck SC2154:
export os_id
export ip
export network
export mask
export cidr
export ip6
export ip6_prefix_length
export ip6_ula
export mac
export dev
export mtu
export gateway
export ip6_gateway
export method
export ip6_method
export metric
export ip6_metric
export dns
export search_domains
export external
export detach
export all_nameservers
export all_search_domains

gen_iface_conf()
{
    cat <<EOT
[Network]
Address=${ip}/${cidr}
EOT

    if [ -n "$dns" ]; then
        for _domain in $dns; do
            echo "DNS=${_domain}"
        done
    fi

    if [ -n "$search_domains" ]; then
        for _search_domain in $search_domains; do
            echo "Domains=${_search_domain}"
        done
    fi

    echo "[Route]"

    if [ -n "$gateway" ]; then
        echo "Gateway=${gateway}"

        if [ -n "$metric" ]; then
            echo "Metric=${metric}"
        fi
    fi

    # Add static routes
    if [ -n "${static_routes}" ]; then

        IFS=',' read -r -a routes <<< "$static_routes"

        for route in "${routes[@]}"
        do
            rsplit=( ${route} )
            dst="${rsplit[0]}"
            gw="${rsplit[2]}"

            echo "[Route]"
            echo "Destination=$dst"
            echo "Gateway=$gw"

        done

    fi

    # Add ONEGATE Proxy static route ip route replace 169.254.16.9 dev eth0
    if missing_onegate_proxy_route; then
        echo "[Route]"
        echo "Destination=${onegate_host}"
        echo "Scope=link"

        unset onegate_proxy_route_missing
    fi

    echo ""
}

gen_dhcp_conf()
{
    case "${dhcp_conf}" in
        ipv4)
            cat <<EOT
[Network]
DHCP=ipv4
EOT
            ;;
        ipv4+auto)
            cat <<EOT
[Network]
DHCP=ipv4
IPv6AcceptRA=yes

[IPv6AcceptRA]
DHCPv6Client=no
EOT
            ;;
        ipv6)
            cat <<EOT
[Network]
DHCP=ipv6
IPv6AcceptRA=yes
EOT
            ;;
        both)
            cat <<EOT
[Network]
DHCP=yes
IPv6AcceptRA=yes
EOT
            ;;
        auto)
            cat <<EOT
[Network]
DHCP=no
IPv6AcceptRA=yes

[IPv6AcceptRA]
DHCPv6Client=no
EOT
            ;;
    esac

    cat <<EOT
[Network]
IPv6PrivacyExtensions=no
EOT

    echo ""
}

gen_alias_conf()
{
    cat <<EOT
[Address]
Address=${ip}/${cidr}
EOT

    echo ""
}

gen_iface6_conf()
{
    cat <<EOT
[Network]
Address=${ip6}/${ip6_prefix_length:-64}
EOT

    echo "IPv6AcceptRA=false"

    if [ -n "$dns" ]; then
        for _domain in $dns; do
            echo "DNS=${_domain}"
        done
    fi

    if [ -n "$search_domains" ]; then
        for _search_domain in $search_domains; do
            echo "Domains=${_search_domain}"
        done
    fi

    cat <<EOT
[Route]
EOT

    if [ -n "$ip6_gateway" ]; then
        echo "Gateway=${ip6_gateway}"

        if [ -n "$ip6_metric" ]; then
            echo "Metric=${ip6_metric}"
        fi
    fi

    if [ -n "$ip6_ula" ]; then
        cat <<EOT
[Network]
Address=${ip6_ula}/64
EOT
    fi

    echo ""
}

gen_alias6_conf()
{
    cat <<EOT
[Address]
Address=${ip6}/${ip6_prefix_length:-64}
EOT

    echo ""
}

gen_ipv6_disable()
{
    cat <<EOT
[Network]
LinkLocalAddressing=no
IPv6AcceptRA=no
EOT

    echo ""
}

# arg: <interface>
is_networkd_iface_managed()
(
    _managed=$(LANG=C networkctl list -al --no-pager --no-legend | \
        awk -v dev="$1" '{if ($2 == dev) print $NF;}' | \
        tr '[:upper:]' '[:lower:]')

    case "${_managed}" in
        ''|unmanaged)
            return 1
            ;;
    esac

    return 0
)

gen_network_configuration()
{
    _context_interfaces=$(get_context_interfaces)

    _networkd_version=$(networkctl --version | head -1 | awk '{print $2}')

    if [ -n "$_networkd_version" ]; then
        # put some dummy low version if not detected
        _networkd_version="100"
    fi

    for _iface in $_context_interfaces; do
        setup_iface_vars "$_iface"

        skip_interface && continue

        # NOTE: This is needed to workaround issue with the networkd metrics.
        #
        # When attaching new NIC from the same vnet on a running system then
        # the networkd will assign some metric to the prefix route of the first
        # NIC but leave out metric for the same prefix route of the new NIC.
        #
        # What happens is that outgoing packets on this subnet will now always
        # use the second NIC even while the incoming packets were targeted for
        # the IP on the first NIC - the result is a broken connection.
        #
        # This occurs at least with systemd/networkd version 248, which is on
        # Cent OS 8 for example.


        if [ $_networkd_version -le 250 ]; then
            if is_networkd_iface_managed "${dev}" ; then
                # networkctl up/down is not on ubuntu <21.04
                networkctl down "$dev" 2>/dev/null || true

                # this is still necessary to really unconfigure the interface
                ip addr flush "$dev"
            fi
        fi

        {
            cat <<EOT
# Generated by one-context
[Match]
Name=${dev}
EOT

            if [ -n "${mtu}" ]; then
                cat <<EOT
[Link]
MTUBytes=${mtu}

## Supported since Debian 10, Ubuntu 18.04, CentOS 8
# [Network]
# IPv6MTUBytes=${mtu}
EOT
            fi

            dhcp_conf=''

            case "${method}" in
                ''|static)
                    [ -n "${ip}" ] && gen_iface_conf
                    ;;
                dhcp)
                    dhcp_conf='ipv4'
                    ;;
            esac

            case "${ip6_method}" in
                ''|static)
                    [ -n "${ip6}" ] && gen_iface6_conf
                    ;;
                auto)
                    if [ -n "${dhcp_conf}" ] ; then
                        dhcp_conf='ipv4+auto'
                    else
                        dhcp_conf='auto'
                    fi
                    ;;
                dhcp)
                    if [ -n "${dhcp_conf}" ] ; then
                        dhcp_conf='both'
                    else
                        dhcp_conf='ipv6'
                    fi
                    ;;
                disable)
                    gen_ipv6_disable
                    ;;
            esac

            [ -n "${dhcp_conf}" ] && gen_dhcp_conf

            _aliases=$(get_interface_alias "$_iface")

            for _nic_alias in $_aliases ; do
                setup_ipadr_vars "$_nic_alias"
                setup_ip6adr_vars "$_nic_alias"
                setup_alias_vars "$_nic_alias"

                if [ -z "${detach}" ]; then
                    if ! is_true "${external}" ; then
                        [ -n "${ip}"  ] && gen_alias_conf
                        [ -n "${ip6}" ] && gen_alias6_conf
                    fi
                fi
            done

        } > "/etc/systemd/network/${dev}.network"

    done
}