#!/bin/bash
#
# .---.                  .              .
# |                      |              |
# |--- .--. .-.  .-.  .-.|  .-. .--.--. |.-.  .-. .--.  .-.
# |    |   (.-' (.-' (   | (   )|  |  | |   )(   )|  | (.-'
# '    '     --'  --'  -' -  -' '  '   -' -'   -' '   -  --'
#
#                    Freedom in the Cloud
#
# Wifi functions

# License
# =======
#
# Copyright (C) 2015-2018 Bob Mottram <bob@freedombone.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

WIFI_CHANNEL=2
WIFI_INTERFACE=wlan0
WIFI_TYPE='wpa2-psk'
WIFI_SSID=
WIFI_PASSPHRASE=
WIFI_HOTSPOT='no'
WIFI_NETWORKS_FILE=~/${PROJECT_NAME}-wifi.cfg

# repo for atheros AR9271 wifi driver
ATHEROS_WIFI_REPO="https://github.com/qca/open-ath9k-htc-firmware.git"

function default_network_config {
    echo '# This file describes the network interfaces available on your system' > /etc/network/interfaces
    echo '# and how to activate them. For more information, see interfaces(5).' >> /etc/network/interfaces
    echo 'source /etc/network/interfaces.d/*' >> /etc/network/interfaces
}

# Debian stretch has a problem where the formerly predictable wlan0 and eth0
# device names get assigned random names. This is a hacky workaround.
# Also adding net.ifnames=0 to kernel options on bootloader may work.
function enable_predictable_device_names {
    test_predictable=$(ls -la /etc/udev/rules.d/80-net-setup-link.rules)
    if [[ "$test_predictable" != *"/dev/null" ]]; then
        ln -s /dev/null /etc/udev/rules.d/80-net-setup-link.rules
        update-initramfs -u
    fi
}

function wifi_is_running {
    wifi_state=$(wpa_cli status)
    if [[ "$wifi_state" == *"COMPLETED"* ]]; then
        echo "1"
    else
        echo "0"
    fi
}

function wifi_static_network_interface {
    NETWORK_IS_STATIC=0
    read_config_param "NETWORK_IS_STATIC"
    if [ ${NETWORK_IS_STATIC} -eq 0 ]; then
        echo '#this line must always be here' > /etc/network/interfaces.d/static
        echo 'iface default inet dhcp' >> /etc/network/interfaces.d/static
    else
        read_config_param "LOCAL_NETWORK_STATIC_IP_ADDRESS"
        read_config_param "ROUTER_IP_ADDRESS"
        echo 'iface default inet static' > /etc/network/interfaces.d/static
        echo "    address ${LOCAL_NETWORK_STATIC_IP_ADDRESS}" >> /etc/network/interfaces.d/static
        echo '    netmask 255.255.255.0' >> /etc/network/interfaces.d/static
        echo "    gateway ${ROUTER_IP_ADDRESS}" >> /etc/network/interfaces.d/static
    fi
}

function setup_wifi_atheros {
    if [[ $(running_as_root) == "0" ]]; then
        return
    fi

    atheros_drivers_file=drivers/firmware-ath9k-htc.deb
    if [ ! -f $atheros_drivers_file ]; then
        if [ ! -f ~/freedombone/$atheros_drivers_file ]; then
            return
        else
            atheros_drivers_file=~/freedombone/$atheros_drivers_file
        fi
    else
        atheros_drivers_file=$(pwd)/$atheros_drivers_file
    fi
    dpkg -i $atheros_drivers_file
    reset_usb_devices
    update_wifi_adaptors
    if [ $IFACE ]; then
        wpa_action ${IFACE} stop
        wpa_cli -i ${IFACE} terminate
        #ifconfig $IFACE up
        ifup $IFACE
    fi
}

function setup_wifi {
    if [[ $SYSTEM_TYPE == "mesh"* ]]; then
        return
    fi
    if [ ! $WIFI_SSID ]; then
        return
    fi
    if [ ${#WIFI_SSID} -lt 2 ]; then
        return
    fi

    if [[ $(is_completed $FUNCNAME) == "1" ]]; then
        return
    fi

    HOTSPOT='no'
    if [[ $WIFI_HOTSPOT != 'no' ]]; then
        HOTSPOT='yes'
    fi

    if [ -f $WIFI_NETWORKS_FILE ]; then
        ${PROJECT_NAME}-wifi --networks $WIFI_NETWORKS_FILE
        mark_completed $FUNCNAME
        return
    fi

    if [[ $WIFI_TYPE != 'none' ]]; then
        if [ ! $WIFI_PASSPHRASE ]; then
            echo $'No wifi passphrase was given'
            return
        fi
        if [ ${#WIFI_PASSPHRASE} -lt 2 ]; then
            echo $'Wifi passphrase was too short'
            return
        fi
        ${PROJECT_NAME}-wifi -s $WIFI_SSID -t $WIFI_TYPE -p $WIFI_PASSPHRASE --hotspot $HOTSPOT --networks $WIFI_NETWORKS_FILE
    else
        ${PROJECT_NAME}-wifi -s $WIFI_SSID -t $WIFI_TYPE --hotspot $HOTSPOT --networks $WIFI_NETWORKS_FILE
    fi
    mark_completed $FUNCNAME
}

# ath9k_htc driver
function install_atheros_wifi {
    if [[ $(is_completed $FUNCNAME) == "1" ]]; then
        return
    fi
    if [ $INSTALLING_ON_BBB != "yes" ]; then
        return
    fi
    if [[ $ENABLE_BATMAN != "yes" ]]; then
        return
    fi
    if [ -d $INSTALL_DIR/open-ath9k-htc-firmware ]; then
        return
    fi
    # have drivers already been installed ?
    if [ -f /lib/firmware/htc_9271.fw ]; then
        return
    fi
    apt-get -yq install build-essential cmake git m4 texinfo
    if [ ! -d $INSTALL_DIR ]; then
        mkdir -p $INSTALL_DIR
    fi
    cd $INSTALL_DIR
    if [ ! -d $INSTALL_DIR/open-ath9k-htc-firmware ]; then
        function_check git_clone
        git_clone $ATHEROS_WIFI_REPO $INSTALL_DIR/open-ath9k-htc-firmware
        if [ ! "$?" = "0" ]; then
            rm -rf $INSTALL_DIR/open-ath9k-htc-firmware
            exit 74283
        fi
    fi
    cd $INSTALL_DIR/open-ath9k-htc-firmware
    git checkout 1.4.0
    make toolchain
    if [ ! "$?" = "0" ]; then
        rm -rf $INSTALL_DIR/open-ath9k-htc-firmware
        exit 24820
    fi
    make firmware
    if [ ! "$?" = "0" ]; then
        rm -rf $INSTALL_DIR/open-ath9k-htc-firmware
        exit 63412
    fi
    cp target_firmware/*.fw /lib/firmware/
    if [ ! "$?" = "0" ]; then
        exit 74681
    fi
    mark_completed $FUNCNAME
}

function update_wifi_adaptors {
    IFACE=
    IFACE_SECONDARY=

    for i in $(seq 10 -1 0); do
        ifdown --force wlan${i} 2> /dev/null
    done

    for i in $(seq 10 -1 0); do
        if grep -q "wlan${i}" /proc/net/dev; then
            if [ ! $IFACE ]; then
                IFACE="wlan${i}"
            else
                IFACE_SECONDARY="wlan${i}"
                return
            fi
        fi
    done
}

function wifi_get_psk {
    ssid=$1
    passphrase=$2

    psk=$(wpa_passphrase "$ssid" "$passphrase" | grep 'psk=' | sed -n 2p | awk -F '=' '{print $2}')
    echo $psk
}

function hotspot_off {
    if [ ! -f /etc/hostapd/hostapd.conf ]; then
        return
    fi
    systemctl stop hostapd

    rm /etc/hostapd/hostapd.conf

    if [ -f /etc/network/interfaces_original_static ]; then
        cp /etc/network/interfaces_original_static /etc/network/interfaces.d/static
    else
        if [ -f /etc/network/interfaces.d/static ]; then
            rm /etc/network/interfaces.d/static
        fi
    fi
    if [ -f /etc/network/interfaces_original_wifi ]; then
        cp /etc/network/interfaces_original_wifi /etc/network/interfaces.d/wifi
    else
        if [ -f /etc/network/interfaces.d/wifi ]; then
            rm /etc/network/interfaces.d/wifi
        fi
    fi
    if [ -f /etc/network/interfaces.d/bridge ]; then
        rm /etc/network/interfaces.d/bridge
    fi

    default_network_config

    wpa_action ${WIFI_INTERFACE} stop
    wpa_cli -i ${WIFI_INTERFACE} terminate
    systemctl restart network-manager
}

function hotspot_on {
    if [ ! -f /etc/default/hostapd ]; then
        echo $'/etc/default/hostapd was not found'
        exit 67241
    fi
    if [ ${#WIFI_PASSPHRASE} -lt 8 ]; then
        echo $'Wifi hotspot passphrase is too short'
        exit 25719
    fi

    sed -i 's|#DAEMON_CONF=.*|DAEMON_CONF="/etc/hostapd/hostapd.conf"|g' /etc/default/hostapd

    echo '### Wireless network name ###' > /etc/hostapd/hostapd.conf
    echo "interface=$WIFI_INTERFACE" >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo '### Set your bridge name ###' >> /etc/hostapd/hostapd.conf
    echo 'bridge=br0' >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo 'driver=nl80211' >> /etc/hostapd/hostapd.conf
    echo "country_code=UK" >> /etc/hostapd/hostapd.conf
    echo "ssid=$WIFI_SSID" >> /etc/hostapd/hostapd.conf
    echo 'hw_mode=g' >> /etc/hostapd/hostapd.conf
    echo 'channel=6' >> /etc/hostapd/hostapd.conf
    echo 'wpa=2' >> /etc/hostapd/hostapd.conf
    echo "wpa_passphrase=$WIFI_PASSPHRASE" >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo '## Key management algorithms ##' >> /etc/hostapd/hostapd.conf
    echo 'wpa_key_mgmt=WPA-PSK' >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo '## Set cipher suites (encryption algorithms) ##' >> /etc/hostapd/hostapd.conf
    echo '## TKIP = Temporal Key Integrity Protocol' >> /etc/hostapd/hostapd.conf
    echo '## CCMP = AES in Counter mode with CBC-MAC' >> /etc/hostapd/hostapd.conf
    echo 'wpa_pairwise=TKIP' >> /etc/hostapd/hostapd.conf
    echo 'rsn_pairwise=CCMP' >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo '## Shared Key Authentication ##'
    echo 'auth_algs=1' >> /etc/hostapd/hostapd.conf
    echo '' >> /etc/hostapd/hostapd.conf
    echo '## Accept all MAC address ###' >> /etc/hostapd/hostapd.conf
    echo 'macaddr_acl=0' >> /etc/hostapd/hostapd.conf

    if [ ! -f /etc/network/interfaces_original_static ]; then
        if [ -f /etc/network/interfaces.d/static ]; then
            cp /etc/network/interfaces.d/static /etc/network/interfaces_original_static
        fi
    fi
    if [ ! -f /etc/network/interfaces_original_wifi ]; then
        if [ -f /etc/network/interfaces.d/wifi ]; then
            cp /etc/network/interfaces.d/wifi /etc/network/interfaces_original_wifi
        fi
    fi

    default_network_config

    echo "allow-hotplug $WIFI_INTERFACE" > /etc/network/interfaces.d/wifi
    echo "iface $WIFI_INTERFACE inet manual" >> /etc/network/interfaces.d/wifi

    echo 'allow-hotplug eth0' >> /etc/network/interfaces.d/static
    echo 'iface eth0 inet manual' >> /etc/network/interfaces.d/static

    echo 'iface br0 inet static' >> /etc/network/interfaces.d/bridge
    echo "    bridge_ports $WIFI_INTERFACE eth0" >> /etc/network/interfaces.d/bridge

    systemctl restart network-manager
    ifup $WIFI_INTERFACE
    systemctl restart hostapd
}

function wifi_store_original_network_settings {
    if [ ! -f /etc/network/interfaces_original ]; then
        if ! grep -q "# wifi enabled" /etc/network/interfaces; then
            cp /etc/network/interfaces /etc/network/interfaces_original
        fi
    fi
}

function wifi_original_network_settings {
    remove_config_param "NETWORK_IS_STATIC"
    if [ -f /etc/network/interfaces.d/static ]; then
        rm /etc/network/interfaces.d/static
    fi
    if [ -f /etc/network/interfaces.d/wifi ]; then
        rm /etc/network/interfaces.d/wifi
    fi
    if [ -f /etc/network/interfaces.d/bridge ]; then
        rm /etc/network/interfaces.d/bridge
    fi
}

function wifi_wpa2_psk {
    ssid=$1
    passphrase=$2

    wifi_store_original_network_settings

    echo 'allow-hotplug eth0' > /etc/network/interfaces.d/static
    echo 'iface eth0 inet dhcp' >> /etc/network/interfaces.d/static

    echo "allow-hotplug ${WIFI_INTERFACE}" > /etc/network/interfaces.d/wifi
    echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces.d/wifi
    echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces.d/wifi
    wifi_static_network_interface

    wpa_passphrase "$ssid" "$passphrase" > $WIFI_CONFIG

    systemctl restart network-manager
    ifup $WIFI_INTERFACE
}

function wifi_none {
    ssid=$1

    wifi_store_original_network_settings

    echo 'allow-hotplug eth0' > /etc/network/interfaces.d/static
    echo 'iface eth0 inet dhcp' >> /etc/network/interfaces.d/static

    echo "allow-hotplug ${WIFI_INTERFACE}" > /etc/network/interfaces.d/wifi
    echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces.d/wifi
    echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces.d/wifi

    wifi_static_network_interface

    echo 'ctrl_interface=/run/wpa_supplicant' > $WIFI_CONFIG
    echo 'update_config=1' >> $WIFI_CONFIG
    echo 'eapol_version=1' >> $WIFI_CONFIG
    echo '' >> $WIFI_CONFIG

    echo 'network={' >> $WIFI_CONFIG
    if [[ "${ssid}" != $'any' && "${ssid}" != $'all' && "${ssid}" != $'open' ]]; then
        echo "  ssid=\"${ssid}\"" >> $WIFI_CONFIG
    fi
    echo '  key_mgmt=NONE' >> $WIFI_CONFIG
    echo '}' >> $WIFI_CONFIG

    systemctl restart network-manager
    ifup $WIFI_INTERFACE
}

function networks_from_file {
    if [ ! -f $WIFI_NETWORKS_FILE ]; then
        exit 4
    fi

    if [[ $(config_param_exists "WIFI_INTERFACE") == "0" ]]; then
        exit 5
    fi
    read_config_param "WIFI_INTERFACE"

    wifi_store_original_network_settings

    echo 'allow-hotplug eth0' > /etc/network/interfaces.d/static
    echo 'iface eth0 inet dhcp' >> /etc/network/interfaces.d/static

    echo "allow-hotplug ${WIFI_INTERFACE}" >> /etc/network/interfaces.d/wifi
    echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces.d/wifi
    echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces.d/wifi

    wifi_static_network_interface

    # remove wpa_supplicant.conf if it exists
    if [ -f $WIFI_CONFIG ]; then
        rm -f $WIFI_CONFIG
    fi

    echo 'ctrl_interface=/run/wpa_supplicant' > $WIFI_CONFIG
    echo 'update_config=1' >> $WIFI_CONFIG
    echo 'eapol_version=1' >> $WIFI_CONFIG
    echo '' >> $WIFI_CONFIG

    ctr=0
    while read -r line
    do
        if [ ${#line} -gt 1 ]; then
            if [[ "$line" != '#'* ]]; then
                if [ $ctr -eq 0 ]; then
                    WIFI_SSID="$line"
                fi
                if [ $ctr -eq 1 ]; then
                    WIFI_TYPE="$line"
                    if [[ $WIFI_TYPE == $'none' || $WIFI_TYPE == $'open' ]]; then
                        echo 'network={' >> $WIFI_CONFIG
                        if [[ "${WIFI_SSID}" != $'any' && "${WIFI_SSID}" != $'all' && "${WIFI_SSID}" != $'open' ]]; then
                            echo "  ssid=\"${WIFI_SSID}\"" >> $WIFI_CONFIG
                        fi
                        echo '  key_mgmt=NONE' >> $WIFI_CONFIG
                        echo '}' >> $WIFI_CONFIG
                        ctr=0
                        continue
                    fi
                fi
                if [ $ctr -eq 2 ]; then
                    WIFI_PASSPHRASE="$line"
                    wpa_passphrase "$WIFI_SSID" "$WIFI_PASSPHRASE" >> $WIFI_CONFIG
                    ctr=0
                    continue
                fi

                ctr=$((ctr + 1))
            fi
        fi
    done < $WIFI_NETWORKS_FILE

    systemctl restart network-manager
    #ifconfig ${WIFI_INTERFACE} up
    ifup $WIFI_INTERFACE
}

function wifi_networks_file_header {
    echo $'# Add wifi networks as follows:' > $WIFI_NETWORKS_FILE
    echo '#' >> $WIFI_NETWORKS_FILE
    echo $'# MySSID' >> $WIFI_NETWORKS_FILE
    echo $'# wpa2-psk' >> $WIFI_NETWORKS_FILE
    echo $'# myWifiPassphrase' >> $WIFI_NETWORKS_FILE
    echo '#' >> $WIFI_NETWORKS_FILE
    echo $'# AnotherSSID' >> $WIFI_NETWORKS_FILE
    echo $'# none' >> $WIFI_NETWORKS_FILE
    echo '#' >> $WIFI_NETWORKS_FILE
}

function create_networks_interactive {
    remove_config_param "WIFI_INTERFACE"
    update_wifi_adaptors
    if [ ! $IFACE ]; then
        # Don't try to configure wifi if there are no adaptors
        return
    fi

    if [ -f $WIFI_NETWORKS_FILE ]; then
        rm $WIFI_NETWORKS_FILE
    fi

    # By default connect to any open wifi
    WIFI_SSID=''
    WIFI_TYPE=$'open'

    wifi_ctr=0
    wifi_networks_done=
    wifi_settings_defined=
    while [ ! $wifi_networks_done ]
    do
        data=$(tempfile 2>/dev/null)
        trap "rm -f $data" 0 1 2 5 15
        wifistr=$"\nTo use this system via wifi (eg. USB dongle) enter the details below, otherwise just select Ok:"
        if [ -f /root/.wifi-only ]; then
            wifistr=$"\nEnter your wifi login details below."
        fi
        dialog --backtitle $"Freedombone Configuration" \
               --title $"Wifi Settings ${wifi_ctr}" \
               --form "$wifistr" 13 65 4 \
               $"SSID (can be 'any'):" 1 1 "$WIFI_SSID" 1 24 30 30 \
               $"Type (open/wpa2-psk):" 2 1 "$WIFI_TYPE" 2 24 10 10 \
               $"Passphrase:" 3 1 "$WIFI_PASSPHRASE" 3 24 50 50 \
               2> $data
        sel=$?
        case $sel in
            1) return;;
            255) return;;
        esac
        WIFI_SSID=$(cat $data | sed -n 1p)
        WIFI_TYPE=$(cat $data | sed -n 2p)
        WIFI_PASSPHRASE=$(cat $data | sed -n 3p)

        # If the wifi-only indicator is present then wifi details must
        # be specified, otherwise they're optional
        if [ ! -f /root/.wifi-only ]; then
            # if these fields are empty then there are no more wifi networks
            if [ ${#WIFI_SSID} -lt 2 ]; then
                wifi_networks_done='yes'
                continue
            fi
            if [ ${#WIFI_TYPE} -lt 2 ]; then
                wifi_networks_done='yes'
                continue
            fi
        fi

        if [ ! -f $WIFI_NETWORKS_FILE ]; then
            wifi_networks_file_header
        fi

        # update the wifi networks file
        echo '' >> $WIFI_NETWORKS_FILE
        echo "$WIFI_SSID" >> $WIFI_NETWORKS_FILE
        echo "$WIFI_TYPE" >> $WIFI_NETWORKS_FILE
        if [ ${#WIFI_PASSPHRASE} -gt 1 ]; then
            echo "$WIFI_PASSPHRASE" >> $WIFI_NETWORKS_FILE
        fi

        if [ ${#WIFI_SSID} -gt 1 ]; then
            if [ ${#WIFI_TYPE} -gt 1 ]; then
                if [[ "${WIFI_TYPE}" == $'none' || "${WIFI_TYPE}" == $'open' ]]; then
                    write_config_param "WIFI_INTERFACE" "$WIFI_INTERFACE"
                    return
                else
                    if [ ${#WIFI_PASSPHRASE} -gt 1 ]; then
                        write_config_param "WIFI_INTERFACE" "$WIFI_INTERFACE"
                        return
                    fi
                fi
            fi
        fi

        # clear values
        WIFI_SSID=
        WIFI_PASSPHRASE=

        wifi_ctr=$((wifi_ctr + 1))
    done
}

function disable_wifi {
    if [[ ${1} == 'yes' || ${1} == 'y' ]]; then
        hotspot_off

        if [ -f /etc/network/interfaces.d/static ]; then
            rm /etc/network/interfaces.d/static
        fi
        if [ -f /etc/network/interfaces.d/wifi ]; then
            rm /etc/network/interfaces.d/wifi
        fi
        if [ -f /etc/network/interfaces.d/bridge ]; then
            rm /etc/network/interfaces.d/bridge
        fi

        default_network_config

        remove_config_param "WIFI_INTERFACE"
        wpa_action ${WIFI_INTERFACE} stop
        wpa_cli -i ${WIFI_INTERFACE} terminate
        systemctl restart network-manager
    else
        networks_from_file
    fi
}

function count_wlan {
    # counts the number of wlan devices
    ctr=0

    for i in $(seq 0 1 10); do
        if grep -q "wlan${i}" /proc/net/dev; then
            ctr=$((ctr + 1))
        fi
    done
    echo $ctr
}

function wifi_exists {
    if grep -q "wlan" /proc/net/dev; then
        echo "1"
    else
        echo "0"
    fi
}

function remove_wifi_startup_script {
    remove_config_param "WIFI_INTERFACE"
    systemd_file=/etc/systemd/system/wifistart.service
    if [ -f $systemd_file ]; then
        systemctl stop wifistart
        systemctl disable wifistart
        rm $systemd_file
    fi
    if [ -f $HOME/${PROJECT_NAME}-wifi.cfg ]; then
        rm $HOME/${PROJECT_NAME}-wifi.cfg
    fi
}

function create_wifi_startup_script {
    systemd_file=/etc/systemd/system/wifistart.service
    echo '[Unit]' > $systemd_file
    echo 'Description=WifiStartup (Start wifi networking)' >> $systemd_file
    echo 'After=syslog.target' >> $systemd_file
    echo 'After=network.target' >> $systemd_file
    echo 'After=remote-fs.target' >> $systemd_file
    echo '' >> $systemd_file
    echo '[Service]' >> $systemd_file
    echo 'Type=simple' >> $systemd_file
    echo 'User=root' >> $systemd_file
    echo 'Group=root' >> $systemd_file
    echo 'WorkingDirectory=/root' >> $systemd_file
    echo "ExecStart=/usr/local/bin/${PROJECT_NAME}-wifi --wait 5 2> /dev/null" >> $systemd_file
    echo '' >> $systemd_file
    echo '[Install]' >> $systemd_file
    echo 'WantedBy=multi-user.target' >> $systemd_file

    systemctl enable wifistart
    systemctl daemon-reload
}

function remove_wifi_startup_script {
    systemd_file=/etc/systemd/system/wifistart.service
    if [ -f $systemd_file ]; then
        systemctl disable wifistart
        systemctl daemon-reload
        rm $systemd_file
    fi
}

# NOTE: deliberately no exit 0