#!/bin/bash

VERSION=0.6.3
PROGNAME="$(basename $0)"

export LC_ALL=C

SCRIPT_UMASK=0122
umask $SCRIPT_UMASK

phead() {
    echo "linux-router $VERSION (https://github.com/garywill/linux-router)"
}
usage() {
    phead
    cat << EOF
Released under LGPL, with no warranty. Use on your own risk.

Usage: $PROGNAME <options>

Options:
    -h, --help              Show this help
    --version               Print version number

    -i <interface>          Interface to make NATed sub-network,
                            and to provide Internet to
                            (To create Wifi hotspot use '--ap' instead)
    -o <interface>          Specify an inteface to provide Internet from.
                            (Note using this with default DNS option may leak
                            queries to other interfaces)
    -n                      Do not provide Internet (See Notice 1)
    --ban-priv              Disallow clients to access my private network
    
    -g <ip>                 This host's IPv4 address in subnet (mask is /24)
                            (example: '192.168.5.1' or '5' shortly)
    -6                      Enable IPv6 (NAT)
    --no4                   Disable IPv4 Internet (not forwarding IPv4)
                            (See Notice 1). Usually used with '-6'
                            
    --p6 <prefix>           Set IPv6 LAN address prefix (length 64) 
                            (example: 'fd00:0:0:5::' or '5' shortly) 
                            Using this enables '-6'
                            
    --dns <ip>|<port>|<ip:port>
                            DNS server's upstream DNS.
                            Use ',' to seperate multiple servers
                            (default: use /etc/resolve.conf)
                            (Note IPv6 addresses need '[]' around)
    --no-dns                Do not serve DNS
    --no-dnsmasq            Disable dnsmasq server (DHCP, DNS, RA)
    --catch-dns             Transparent DNS proxy, redirect packets(TCP/UDP) 
                            whose destination port is 53 to this host
    --log-dns               Show DNS query log
    --dhcp-dns <IP1[,IP2]>|no
                            Set IPv4 DNS offered by DHCP (default: this host)
    --dhcp-dns6 <IP1[,IP2]>|no
                            Set IPv6 DNS offered by DHCP (RA) 
                            (default: this host)
                            (Note IPv6 addresses need '[]' around)
    --hostname <name>       DNS server associate this name with this host.
                            Use '-' to read name from /etc/hostname
    -d                      DNS server will take into account /etc/hosts
    -e <hosts_file>         DNS server will take into account additional 
                            hosts file
    
    --mac <MAC>             Set MAC address
    --random-mac            Use random MAC address
 
    --tp <port>             Transparent proxy,
                            redirect non-LAN TCP and UDP traffic to port.
                            (usually used with '--dns')
    
  Wifi hotspot options:
    --ap <wifi interface> <SSID>
                            Create Wifi access point
    -p, --password <password>   
                            Wifi password
    --qr                    Show Wifi QR code in terminal
    
    --hidden                Hide access point (not broadcast SSID)
    --no-virt               Do not create virtual interface
                            Using this you can't use same wlan interface
                            for both Internet and AP
    -c <channel>            Channel number (default: 1)
    --country <code>        Set two-letter country code for regularity
                            (example: US)
    --freq-band <GHz>       Set frequency band: 2.4 or 5 (default: 2.4)
    --driver                Choose your WiFi adapter driver (default: nl80211)
    -w <WPA version>        '2' for WPA2, '1' for WPA, '1+2' for both
                            (default: 2)
    --psk                   Use 64 hex digits pre-shared-key instead of
                            passphrase
    --mac-filter            Enable Wifi hotspot MAC address filtering
    --mac-filter-accept     Location of Wifi hotspot MAC address filter list
                            (defaults to /etc/hostapd/hostapd.accept)
    --hostapd-debug <level> 1 or 2. Passes -d or -dd to hostapd
    --isolate-clients       Disable wifi communication between clients
    
    --ieee80211n            Enable IEEE 802.11n (HT)
    --ieee80211ac           Enable IEEE 802.11ac (VHT)
    --ht_capab <HT>         HT capabilities (default: [HT40+])
    --vht_capab <VHT>       VHT capabilities
    
    --no-haveged            Do not run haveged automatically when needed

  Instance managing:
    --daemon                Run in background
    -l, --list-running      Show running instances
    --lc, --list-clients <id|interface>     
                            List clients of an instance. Or list neighbors of
                            an interface, even if it isn't handled by us.
                            (passive mode)
    --stop <id>             Stop a running instance
        For <id> you can use PID or subnet interface name.
        You can get them with '--list-running'

    Notice 1:   This script assume your host's default policy won't forward
                packets, so the script won't explictly ban forwarding in any
                mode. In some unexpected case may cause unwanted packets 
                leakage between 2 networks, which you should be aware of if you
                want isolated network
                
Examples:
    $PROGNAME -i eth1
    $PROGNAME --ap wlan0 MyAccessPoint
    $PROGNAME --ap wlan0 MyAccessPoint -p MyPassPhrase
    $PROGNAME -i eth1 --tp <transparent-proxy> --dns <dns-proxy>
EOF
}

check_empty_option(){
    if [[ "$1" == "" ]]; then
        usage
        exit 0
    fi
}


define_global_variables(){
    # user options
    GATEWAY=  # IPv4 address for this host
    PREFIX6=  # IPv6 LAN address prefix for this host
    IID6=1    # IPv6 LAN ID for this host
    IPV6=0  # enable ipv6
    NO4=0   # no IPv4 Internet
    BANLAN=0 # ban clients from accessing private addresses
    DHCP_DNS=gateway  # which ipv4 DNS the DHCP gives clients
    DHCP_DNS6=gateway # which ipv6 DNS the DHCP gives clients
    dnsmasq_NO_DNS=0  # disable dns server
    NO_DNSMASQ=0  # disable dnsmasq (dns and dhcp)
    CATCH_DNS=0   # catch clients 53 port packets
    SHOW_DNS_QUERY=0  # log dns
    ETC_HOSTS=0
    ADDN_HOSTS=
    CONN_IFACE=    # which interface user choose to use to create network
    INTERNET_IFACE= # which interface to get Internet from
    THISHOSTNAME=   # this host's name the DNS tells clients 
    TP_PORT=  # transparent proxy port
    DNS=  # upstream DNS
    MAC_USE_RANDOM=0
    NEW_MACADDR=
    DAEMONIZE=0
    
    # script variables
    SUBNET_IFACE=  # which interface to create network
    SHARE_METHOD=nat 
    OLD_MACADDR=
    

    ##### wifi hotspot
    # user options
    HIDDEN=0 # hidden wifi hotspot
    WIFI_IFACE=
    CHANNEL=default 
    WPA_VERSION=2
    MAC_FILTER=0
    MAC_FILTER_ACCEPT=/etc/hostapd/hostapd.accept
    IEEE80211N=0
    IEEE80211AC=0
    HT_CAPAB='[HT40+]'
    VHT_CAPAB=
    DRIVER=nl80211
    NO_VIRT=0 # not use virtual interface
    COUNTRY=
    FREQ_BAND=2.4
    NO_HAVEGED=0
    HOSTAPD_DEBUG_ARGS=
    USE_PSK=0
    ISOLATE_CLIENTS=0
    QR=0 # show wifi qr
    
    # script variables
    VWIFI_IFACE=  # virtual wifi interface name, if created
    AP_IFACE=     # can be VWIFI_IFACE or WIFI_IFACE
    USE_IWCONFIG=0  # some device can't use iw
    
    #######
    
    #-- to deal with info of a running instance. then will exit
    LIST_RUNNING=0
    STOP_ID=
    LIST_CLIENTS_ID=

    # -- variables for running
    CONFDIR=
    NM_RUNNING=0
    NM_UNM_LIST=  # it's called "list" but for now one interface
}

parse_user_options(){
    while [[ -n "$1" ]]; do
        case "$1" in
            -h|--help)
                usage
                exit 0
                ;;
            --version)
                echo "$VERSION"
                exit 0
                ;;
            -i)
                shift
                CONN_IFACE="$1"
                shift
                ;;
            -o)
                shift
                INTERNET_IFACE="$1"
                shift
                echo ""
                echo "WARN: Since you're using in this mode, make sure you've read Notice 1" >&2
                echo ""
                ;;
            -n)
                shift
                SHARE_METHOD=none
                echo ""
                echo "WARN: Since you're using in this mode, make sure you've read Notice 1" >&2
                echo ""
                ;;
            --ban-priv)
                shift
                BANLAN=1
                ;;
            --tp)
                shift
                TP_PORT="$1"
                SHARE_METHOD=redsocks
                shift
                ;;
                
                
            -g)
                shift
                GATEWAY="$1"
                shift
                ;;
            -6)
                shift
                IPV6=1
                ;;
            --no4)
                shift
                NO4=1
                echo ""
                echo "WARN: Since you're using in this mode, make sure you've read Notice 1" >&2
                echo ""
                ;;
            --p6)
                shift
                PREFIX6="$1"
                IPV6=1
                shift
                ;;
            --mac)
                shift
                NEW_MACADDR="$1"
                shift
                ;;
            --random-mac)
                shift
                MAC_USE_RANDOM=1
                ;;
                
            --dns)
                shift
                DNS="$1"
                shift
                ;;
            --no-dns)
                shift
                dnsmasq_NO_DNS=1
                ;;
            --no-dnsmasq)
                shift
                NO_DNSMASQ=1
                ;;
            --dhcp-dns)
                shift
                DHCP_DNS="$1"
                shift
                ;;
            --dhcp-dns6)
                shift
                DHCP_DNS6="$1"
                shift
                ;;
            --catch-dns)
                shift
                CATCH_DNS=1
                ;;    
            --log-dns)
                shift
                SHOW_DNS_QUERY=1
                ;;
            --hostname)
                shift
                THISHOSTNAME="$1"
                shift
                ;;
            -d)
                shift
                ETC_HOSTS=1
                ;;
            -e)
                shift
                ADDN_HOSTS="$1"
                shift
                ;;
            
            --isolate-clients)
                shift
                ISOLATE_CLIENTS=1
                ;;
                
            --ap)
                shift
                WIFI_IFACE="$1"
                shift
                SSID="$1"
                shift
                ;;
            -p|--password)
                shift
                PASSPHRASE="$1"
                shift
                ;;
            --qr)
                shift
                QR=1
                ;;
                
                
            --hidden)
                shift
                HIDDEN=1
                ;;
            --mac-filter)
                shift
                MAC_FILTER=1
                ;;
            --mac-filter-accept)
                shift
                MAC_FILTER_ACCEPT="$1"
                shift
                ;;

            -c)
                shift
                CHANNEL="$1"
                shift
                ;;
            -w)
                shift
                WPA_VERSION="$1"
                [[ "$WPA_VERSION" == "2+1" ]] && WPA_VERSION=1+2
                shift
                ;;

            --ieee80211n)
                shift
                IEEE80211N=1
                ;;
            --ieee80211ac)
                shift
                IEEE80211AC=1
                ;;
            --ht_capab)
                shift
                HT_CAPAB="$1"
                shift
                ;;
            --vht_capab)
                shift
                VHT_CAPAB="$1"
                shift
                ;;
            --driver)
                shift
                DRIVER="$1"
                shift
                ;;
            --no-virt)
                shift
                NO_VIRT=1
                ;;

            --country)
                shift
                COUNTRY="$1"
                shift
                ;;
            --freq-band)
                shift
                FREQ_BAND="$1"
                shift
                ;;
            --no-haveged)
                shift
                NO_HAVEGED=1
                ;;
            --hostapd-debug)
                shift
                if [ "x$1" = "x1" ]; then
                    HOSTAPD_DEBUG_ARGS="-d"
                elif [ "x$1" = "x2" ]; then
                    HOSTAPD_DEBUG_ARGS="-dd"
                else
                    printf "Error: argument for --hostapd-debug expected 1 or 2, got %s\n" "$1"
                    exit 1
                fi
                shift
                ;;
            --psk)
                shift
                USE_PSK=1
                ;;

            --daemon)
                shift
                DAEMONIZE=1
                ;;
            --stop)
                shift
                STOP_ID="$1"
                shift
                ;;
            -l|--list-running)
                shift
                LIST_RUNNING=1
                ;;
            --lc|--list-clients)
                shift
                LIST_CLIENTS_ID="$1"
                shift
                ;;

            *)
                echo  "Invalid parameter: $1" 1>&2
                exit 1
                ;;
        esac
    done
}


# seperate ip and port
sep_ip_port() {
    # usage: sep_ip_port <ip:port> <var for ip> <var for port>
    # input <ip:port> can be:
    #   port (ip is 127.0.0.1)
    #   ipv4
    #   [ipv6]
    #   ipv4:port
    #   [ipv6]:port
    local IP
    local PORT
    local INPUT
    INPUT="$1"
    if (echo "$INPUT" | grep '\.' >/dev/null 2>&1) ;then  
        if (echo "$INPUT" | grep ':' >/dev/null 2>&1) ;then
            # ipv4 + port
            IP="$(echo $INPUT | cut -d: -f1)"
            PORT="$(echo $INPUT | cut -d: -f2)"
        else
            # ipv4
            IP="$INPUT"
        fi
    elif (echo "$INPUT" | grep '\]' >/dev/null 2>&1) ;then 
        if (echo "$INPUT" | grep '\]\:' >/dev/null 2>&1) ;then
            # ipv6 + port
            IP="$(echo $INPUT | cut -d']' -f1 | cut -d'[' -f2)"
            PORT="$(echo $INPUT | cut -d']' -f2 |cut -d: -f2)"
        else
            # ipv6
            IP="$(echo $INPUT | cut -d']' -f1 | cut -d'[' -f2)"
        fi
    else 
        # port
        IP='127.0.0.1'
        PORT="$INPUT"
    fi
    printf -v "$2" %s "$IP"
    printf -v "$3" %s "$PORT"
}

#=========================
is_interface() {
    [[ -z "$1" ]] && return 1
    [[ -d "/sys/class/net/${1}" ]]
}

get_interface_phy_device() { # only for wifi interface
    local x
    for x in /sys/class/ieee80211/*; do
        [[ ! -e "$x" ]] && continue
        if [[ "${x##*/}" = "$1" ]]; then
            echo "$1"
            return 0
        elif [[ -e "$x/device/net/$1" ]]; then
            echo ${x##*/}
            return 0
        elif [[ -e "$x/device/net:$1" ]]; then
            echo ${x##*/}
            return 0
        fi
    done
    echo "Failed to get phy interface" >&2
    return 1
}

get_adapter_info() { # only for wifi interface
    local iPHY
    iPHY=$(get_interface_phy_device "$1")
    [[ $? -ne 0 ]] && return 1
    iw phy $iPHY info
}

get_adapter_kernel_module() {
    local MODULE
    MODULE=$(readlink -f "/sys/class/net/$1/device/driver/module")
    echo ${MODULE##*/}
}

can_be_sta_and_ap() {
    # iwconfig does not provide this information, assume false
    [[ $USE_IWCONFIG -eq 1 ]] && return 1
    if [[ "$(get_adapter_kernel_module "$1")" == "brcmfmac" ]]; then
        echo "WARN: brmfmac driver doesn't work properly with virtual interfaces and" >&2
        echo "      it can cause kernel panic. For this reason we disallow virtual" >&2
        echo "      interfaces for your adapter." >&2
        echo "      For more info: https://github.com/oblique/create_ap/issues/203" >&2
        return 1
    fi
    get_adapter_info "$1" | grep -E '{.* managed.* AP.*}' > /dev/null 2>&1 && return 0
    get_adapter_info "$1" | grep -E '{.* AP.* managed.*}' > /dev/null 2>&1 && return 0
    return 1
}

can_be_ap() {
    # iwconfig does not provide this information, assume true
    [[ $USE_IWCONFIG -eq 1 ]] && return 0
    get_adapter_info "$1" | grep -E '\* AP$' > /dev/null 2>&1 && return 0
    return 1
}

can_transmit_to_channel() {
    local IFACE CHANNEL_NUM CHANNEL_INFO
    IFACE=$1
    CHANNEL_NUM=$2

    if [[ $USE_IWCONFIG -eq 0 ]]; then
        if [[ $FREQ_BAND == 2.4 ]]; then
            CHANNEL_INFO=$(get_adapter_info ${IFACE} | grep " 24[0-9][0-9] MHz \[${CHANNEL_NUM}\]")
        else
            CHANNEL_INFO=$(get_adapter_info ${IFACE} | grep " \(49[0-9][0-9]\|5[0-9]\{3\}\) MHz \[${CHANNEL_NUM}\]")
        fi
        [[ -z "${CHANNEL_INFO}" ]] && return 1
        [[ "${CHANNEL_INFO}" == *no\ IR* ]] && return 1
        [[ "${CHANNEL_INFO}" == *disabled* ]] && return 1
        return 0
    else
        CHANNEL_NUM=$(printf '%02d' ${CHANNEL_NUM})
        CHANNEL_INFO=$(iwlist ${IFACE} channel | grep -E "Channel[[:blank:]]${CHANNEL_NUM}[[:blank:]]?:")
        [[ -z "${CHANNEL_INFO}" ]] && return 1
        return 0
    fi
}

# taken from iw/util.c
ieee80211_frequency_to_channel() {
    local FREQ=$1
    if [[ $FREQ -eq 2484 ]]; then
        echo 14
    elif [[ $FREQ -lt 2484 ]]; then
        echo $(( ($FREQ - 2407) / 5 ))
    elif [[ $FREQ -ge 4910 && $FREQ -le 4980 ]]; then
        echo $(( ($FREQ - 4000) / 5 ))
    elif [[ $FREQ -le 45000 ]]; then
        echo $(( ($FREQ - 5000) / 5 ))
    elif [[ $FREQ -ge 58320 && $FREQ -le 64800 ]]; then
        echo $(( ($FREQ - 56160) / 2160 ))
    else
        echo 0
    fi
}

is_5ghz_frequency() {
    [[ $1 =~ ^(49[0-9]{2})|(5[0-9]{3})$ ]]
}

is_interface_wifi_connected() {
    if [[ $USE_IWCONFIG -eq 0 ]]; then
        iw dev "$1" link 2>&1 | grep -E '^Connected to' > /dev/null 2>&1 && return 0
    else
        iwconfig "$1" 2>&1 | grep -E 'Access Point: [0-9a-fA-F]{2}:' > /dev/null 2>&1 && return 0
    fi
    return 1
}


is_unicast_macaddr() {
    local x
    x=$(echo "$1" | cut -d: -f1)
    x=$(printf '%d' "0x${x}")
    [[ $(expr $x % 2) -eq 0 ]]
}

get_interface_mac() {
    is_interface "$1" || return
    cat "/sys/class/net/${1}/address"
}

alloc_new_vface_name() { # only for wifi
    local i=0
    local v_iface_name=
    while :; do
        v_iface_name="x$i${WIFI_IFACE}"
        if ! is_interface ${v_iface_name} && [[ ! -f $COMMON_CONFDIR/vfaces/${v_iface_name} ]]; then
            mkdir -p $COMMON_CONFDIR/vfaces
            touch $COMMON_CONFDIR/vfaces/${v_iface_name}
            echo "${v_iface_name}"
            return
        fi
        i=$((i + 1))
    done
}

dealloc_vface_name() {
    rm -f $COMMON_CONFDIR/vfaces/$1
}

#======

get_all_mac_in_system() {
    cat /sys/class/net/*/address
}

get_new_macaddr_according_to_existing() {
    local REALDEV OLDMAC NEWMAC LAST_BYTE i
    REALDEV=$1
    OLDMAC=$(get_interface_mac "$REALDEV")
    NEWMAC=""
    LAST_BYTE=$(printf %d 0x${OLDMAC##*:})
    for i in {10..240}; do
        NEWMAC="${OLDMAC%:*}:$(printf %02x $(( ($LAST_BYTE + $i) % 256 )))"
        (get_all_mac_in_system | grep "$NEWMAC" > /dev/null 2>&1) || break
    done
    echo "$NEWMAC"
}

generate_random_mac() {
    local r1 r2 r3 r4 r5 r6 
    local RAND_MAC
    while :; do
        r1=$( printf "%02x" $(($RANDOM%256/4*4)) )
        r2=$( printf "%02x" $(($RANDOM%256)) )
        r3=$( printf "%02x" $(($RANDOM%256)) )
        r4=$( printf "%02x" $(($RANDOM%256)) )
        r5=$( printf "%02x" $(($RANDOM%256)) )
        r6=$( printf "%02x" $(($RANDOM%256)) )
        RAND_MAC="$r1:$r2:$r3:$r4:$r5:$r6"
        ( ! ip link | grep "link" | grep $RAND_MAC > /dev/null 2>&1 ) && \
        ( ! ip maddress | grep "link" | grep $RAND_MAC > /dev/null 2>&1 ) && \
        ( ! ip neigh | grep "lladdr $RAND_MAC" > /dev/null 2>&1 ) && \
        ( ! get_all_mac_in_system | grep $RAND_MAC ) && \
        break
    done
    echo "$RAND_MAC"
}


is_ip4_lan_range_available() { # checks 192.168.x.x
    ( ip -4 address | grep "inet 192\.168\.$1\." > /dev/null 2>&1 ) && return 1
    ( ip -4 route | grep "^192\.168\.$1\." > /dev/null 2>&1 ) && return 1
    ( ip -4 route get 192.168.$1.0 2>&1 | grep -E "\bvia\b|\bunreachable\b" > /dev/null 2>&1 ) && \
    ( ip -4 route get 192.168.$1.255 2>&1 | grep  -E "\bvia\b|\bunreachable\b" > /dev/null 2>&1 )  && return 0
    return 1
}
is_ip6_lan_range_available() {  # checks fdxx::
    ( ip -6 address | grep -i "inet6 fd$1:$2$3:$4$5:$6$7:" > /dev/null 2>&1 ) && return 1
    ( ip -6 route | grep -i "^fd$1:$2$3:$4$5:$6$7:" > /dev/null 2>&1 ) && return 1
    ( ip -6 route get fd$1:$2$3:$4$5:$6$7:: 2>&1 | grep -E "\bvia\b|\bunreachable\b" > /dev/null 2>&1 ) && \
    ( ip -6 route get fd$1:$2$3:$4$5:$6$7:ffff:ffff:ffff:ffff 2>&1 | grep -E "\bvia\b|\bunreachable\b" > /dev/null 2>&1 )  && return 0
    return 1
}

generate_random_ip4() {
    local random_ip4
    while :; do
        random_ip4=$(($RANDOM%256))
        is_ip4_lan_range_available $random_ip4 && break
    done
    echo "192.168.$random_ip4.1"
}
generate_random_lan_ip6_prefix() {
    local r1 r2 r3 r4 r5 r6 r7
    while :; do
        r1=$( printf "%x" $(($RANDOM%240+16)) )
        r2=$( printf "%x" $(($RANDOM%240+16)) )
        r3=$( printf "%x" $(($RANDOM%240+16)) )
        r4=$( printf "%x" $(($RANDOM%240+16)) )
        r5=$( printf "%x" $(($RANDOM%240+16)) )
        r6=$( printf "%x" $(($RANDOM%240+16)) )
        r7=$( printf "%x" $(($RANDOM%240+16)) )
        is_ip6_lan_range_available $r1 $r2 $r3 $r4 $r5 $r6 $r7 && break
    done
    echo "fd$r1:$r2$r3:$r4$r5:$r6$r7::"
}



# start haveged when needed
haveged_watchdog() {
    local show_warn=1
    while :; do
        if [[ $(cat /proc/sys/kernel/random/entropy_avail) -lt 1000 ]]; then
            if ! which haveged > /dev/null 2>&1; then
                if [[ $show_warn -eq 1 ]]; then
                    echo "WARN: Low entropy detected. We recommend you to install \`haveged'" 1>&2
                    show_warn=0
                fi
            elif ! pidof haveged > /dev/null 2>&1; then # TODO judge zombie ?
                echo "Low entropy detected, starting haveged" 1>&2
                # boost low-entropy
                haveged -w 1024 -p $COMMON_CONFDIR/haveged.pid
            fi
        fi
        sleep 2
    done
}
pid_watchdog() {
    local PID="$1"
    local SLEEP="$2"
    local ERR_MSG="$3"
    local ST
    while true
    do 
        if [[ -e "/proc/$PID" ]]; then
            ST="$(cat "/proc/$PID/status" | grep "^State:" | awk '{print $2}')"
            if [[ "$ST" != 'Z' ]]; then
                sleep $SLEEP
                continue
            fi
        fi
        die "$ERR_MSG"
    done
    
}
#========


# only support NetworkManager >= 0.9.9
is_nm_running() {
    if (which nmcli >/dev/null 2>&1 ) && (nmcli -t -f RUNNING g 2>&1 | grep -E '^running$' >/dev/null 2>&1 ) ; then
        echo 1
    else
        echo 0
    fi
}

nm_knows() {
    (nmcli dev show $1 | grep -E "^GENERAL.STATE:" >/dev/null 2>&1 ) && return 0 # nm sees
    return 1 # nm doesn't see this interface
}
nm_get_manage() { # get an interface's managed state
    local s
    s=$(nmcli dev show $1 | grep -E "^GENERAL.STATE:") || return 2 # no such interface
    (echo $s | grep "unmanaged" >/dev/null 2>&1) && return 1 # unmanaged
    return 0 # managed
}
nm_set_unmanaged() {
    while ! nm_knows $1 ; do # wait for virtual wifi interface seen by NM
        sleep 0.5
    done
    if nm_get_manage $1 ;then
        echo "Set $1 unmanaged by NetworkManager"
        nmcli dev set $1 managed no || die "Failed to set $1 unmanaged by NetworkManager"
        NM_UNM_LIST=$1
        sleep 1
    fi
}

nm_set_managed() {
    nmcli dev set $1 managed yes
    NM_UNM_LIST=
}
nm_restore_manage() {
    if [[ $NM_UNM_LIST ]]; then
        echo "Restore $NM_UNM_LIST managed by NetworkManager"
        nm_set_managed $NM_UNM_LIST
        sleep 0.5
    fi
}
#=========
check_iptables()
{
    echo
    iptables --version
    
    if which firewall-cmd > /dev/null 2>&1; then
        if [[ "$(firewall-cmd --state)" == "running" ]]; then
            echo "firewalld is running ($(firewall-cmd --version))"
            echo -e "\nWARN: We haven't completed the compatibility with firewalld.\nWARN: If you see any trouble, try:\nWARN:     1) 'firewall-cmd --zone=trusted --add-interface=<SUBN_IFACE>'\nWARN:     2) disable firewalld\n" >&2 
            # TODO
        fi
    fi
}
iptables_()
{
    # NETFILTER_XT_MATCH_COMMENT would be a env variable if user wants to disable '-m comment'
    if [[ "$NETFILTER_XT_MATCH_COMMENT" == "0" ]]; then
        iptables -w $@ 
    else
        iptables -w $@ -m comment --comment "lnxrouter-$$-$SUBNET_IFACE"
    fi
    return $?
}
ip6tables_()
{
    if [[ "$NETFILTER_XT_MATCH_COMMENT" == "0" ]]; then
        ip6tables -w $@
    else
        ip6tables -w $@ -m comment --comment "lnxrouter-$$-$SUBNET_IFACE"
    fi
    return $?
}

start_nat() {
    if [[ $INTERNET_IFACE ]]; then
        IPTABLES_NAT_OUT="-o ${INTERNET_IFACE}"
        IPTABLES_NAT_IN="-i ${INTERNET_IFACE}"
        MASQUERADE_NOTOUT=""
    else
        MASQUERADE_NOTOUT="! -o ${SUBNET_IFACE}"
    fi
    echo
    echo "iptables: NAT "
    if [[ $NO4 -eq 0 ]]; then
        iptables_ -v -t nat -I POSTROUTING -s ${GATEWAY%.*}.0/24 $IPTABLES_NAT_OUT $MASQUERADE_NOTOUT ! -d ${GATEWAY%.*}.0/24  -j MASQUERADE || die
        iptables_ -v -I FORWARD -i ${SUBNET_IFACE} $IPTABLES_NAT_OUT -s ${GATEWAY%.*}.0/24 -j ACCEPT || die
        iptables_ -v -I FORWARD -o ${SUBNET_IFACE} $IPTABLES_NAT_IN  -d ${GATEWAY%.*}.0/24 -j ACCEPT || die
    fi
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -v -t nat -I POSTROUTING -s ${PREFIX6}/64 $IPTABLES_NAT_OUT $MASQUERADE_NOTOUT ! -d ${PREFIX6}/64  -j MASQUERADE || die
        ip6tables_ -v -I FORWARD -i ${SUBNET_IFACE} $IPTABLES_NAT_OUT -s ${PREFIX6}/64 -j ACCEPT || die
        ip6tables_ -v -I FORWARD -o ${SUBNET_IFACE} $IPTABLES_NAT_IN   -d ${PREFIX6}/64 -j ACCEPT || die
    fi
}
stop_nat() {
    echo "iptables: stop NAT"
    if [[ $NO4 -eq 0 ]]; then
        iptables_ -t nat -D POSTROUTING -s ${GATEWAY%.*}.0/24 $IPTABLES_NAT_OUT $MASQUERADE_NOTOUT ! -d ${GATEWAY%.*}.0/24  -j MASQUERADE
        iptables_ -D FORWARD -i ${SUBNET_IFACE} $IPTABLES_NAT_OUT -s ${GATEWAY%.*}.0/24 -j ACCEPT
        iptables_ -D FORWARD -o ${SUBNET_IFACE} $IPTABLES_NAT_IN  -d ${GATEWAY%.*}.0/24 -j ACCEPT
    fi
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -t nat -D POSTROUTING -s ${PREFIX6}/64 $IPTABLES_NAT_OUT $MASQUERADE_NOTOUT ! -d ${PREFIX6}/64  -j MASQUERADE
        ip6tables_ -D FORWARD -i ${SUBNET_IFACE} $IPTABLES_NAT_OUT -s ${PREFIX6}/64 -j ACCEPT
        ip6tables_ -D FORWARD -o ${SUBNET_IFACE} $IPTABLES_NAT_IN  -d ${PREFIX6}/64 -j ACCEPT
    fi
}

start_ban_lan() {
    echo
    echo "iptables: Disallow clients to access LAN"
    iptables_ -N BANLAN-f-${SUBNET_IFACE}  || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 0.0.0.0/8 -j REJECT || die # TODO: use array
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 10.0.0.0/8 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 100.64.0.0/10 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 127.0.0.0/8 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 169.254.0.0/16 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 172.16.0.0/12 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 192.168.0.0/16 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 224.0.0.0/4 -j REJECT || die
    iptables_ -v -I BANLAN-f-${SUBNET_IFACE} -d 255.255.255.255 -j REJECT || die
    
    iptables_ -I FORWARD -i ${SUBNET_IFACE} -j BANLAN-f-${SUBNET_IFACE} || die
    
    iptables_ -N BANLAN-i-${SUBNET_IFACE}
    #iptables_ -v -I BANLAN-i-${SUBNET_IFACE} -i ${SUBNET_IFACE} -j REJECT || die
    iptables_ -v -I BANLAN-i-${SUBNET_IFACE} -i ${SUBNET_IFACE} ! -p icmp -j REJECT || die
    # TODO: ipv6 need icmp to function. maybe we can block some unneeded icmp to improve security
    
    iptables_ -I INPUT -i ${SUBNET_IFACE} -j BANLAN-i-${SUBNET_IFACE} || die
    
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -N BANLAN-f-${SUBNET_IFACE}  || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d fc00::/7 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d fe80::/10 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d ff00::/8 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d ::1 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d ::/128 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d ::ffff:0:0/96 -j REJECT || die
        ip6tables_ -v -I BANLAN-f-${SUBNET_IFACE} -d ::ffff:0:0:0/96 -j REJECT || die

        ip6tables_ -I FORWARD -i ${SUBNET_IFACE} -j BANLAN-f-${SUBNET_IFACE} || die
        
        ip6tables_ -N BANLAN-i-${SUBNET_IFACE}  || die
        #ip6tables_ -v -I BANLAN-i-${SUBNET_IFACE} -i ${SUBNET_IFACE} -j REJECT || die
        ip6tables_ -v -I BANLAN-i-${SUBNET_IFACE} -i ${SUBNET_IFACE} ! -p icmpv6 -j REJECT || die

        ip6tables_ -I INPUT -i ${SUBNET_IFACE} -j BANLAN-i-${SUBNET_IFACE} || die
    fi
}
stop_ban_lan() {
    echo "iptables: Unban clients' LAN access"
    
    iptables_ -D FORWARD -i ${SUBNET_IFACE} -j BANLAN-f-${SUBNET_IFACE} 
    
    iptables_ -F BANLAN-f-${SUBNET_IFACE}
    iptables_ -X BANLAN-f-${SUBNET_IFACE}
    
    iptables_ -D INPUT -i ${SUBNET_IFACE} -j BANLAN-i-${SUBNET_IFACE}
    
    iptables_ -F BANLAN-i-${SUBNET_IFACE}
    iptables_ -X BANLAN-i-${SUBNET_IFACE}
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -D FORWARD -i ${SUBNET_IFACE} -j BANLAN-f-${SUBNET_IFACE} 
    
        ip6tables_ -F BANLAN-f-${SUBNET_IFACE}
        ip6tables_ -X BANLAN-f-${SUBNET_IFACE} 
        
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -j BANLAN-i-${SUBNET_IFACE}
        
        ip6tables_ -F BANLAN-i-${SUBNET_IFACE}
        ip6tables_ -X BANLAN-i-${SUBNET_IFACE} 
    fi
}

allow_dns_port() {
    echo
    echo "iptables: allow DNS"
    iptables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -d ${GATEWAY} -p tcp -m tcp --dport 53 -j ACCEPT || die
    iptables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -d ${GATEWAY} -p udp -m udp --dport 53 -j ACCEPT || die
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -d ${GATEWAY6} -p tcp -m tcp --dport 53 -j ACCEPT || die
        ip6tables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -d ${GATEWAY6} -p udp -m udp --dport 53 -j ACCEPT || die
    fi
}
unallow_dns_port() {
    echo "iptables: unallow DNS"
    iptables_ -D INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -d ${GATEWAY} -p tcp -m tcp --dport 53 -j ACCEPT
    iptables_ -D INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -d ${GATEWAY}  -p udp -m udp --dport 53 -j ACCEPT
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -d ${GATEWAY6} -p tcp -m tcp --dport 53 -j ACCEPT
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -d ${GATEWAY6} -p udp -m udp --dport 53 -j ACCEPT
    fi
}

start_catch_dns() {
    echo
    echo "iptables: redirect all TCP/UDP packet that destination port is 53"
    iptables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY} -p udp -m udp --dport 53 -j REDIRECT --to-ports 53 || die
    iptables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY} -p tcp -m tcp --dport 53 -j REDIRECT --to-ports 53 || die
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY6} -p udp -m udp --dport 53 -j REDIRECT --to-ports 53 || die
        ip6tables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY6} -p tcp -m tcp --dport 53 -j REDIRECT --to-ports 53 || die
    fi
}
stop_catch_dns() {
    echo "iptables: stop redirecting DNS queries"
    iptables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY} -p udp -m udp --dport 53 -j REDIRECT --to-ports 53 
    iptables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY} -p tcp -m tcp --dport 53 -j REDIRECT --to-ports 53 
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY6} -p udp -m udp --dport 53 -j REDIRECT --to-ports 53 
        ip6tables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} ! -d ${GATEWAY6} -p tcp -m tcp --dport 53 -j REDIRECT --to-ports 53 
    fi
}

allow_dhcp() {
    echo 
    echo "iptables: allow dhcp"
    iptables_ -v -I INPUT -i ${SUBNET_IFACE} -p udp -m udp --dport 67 -j ACCEPT || die
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -v -I INPUT -i ${SUBNET_IFACE} -p udp -m udp --dport 547 -j ACCEPT || die
    fi
}
unallow_dhcp() {
    echo "iptables: unallow dhcp"
    iptables_ -D INPUT -i ${SUBNET_IFACE} -p udp -m udp --dport 67 -j ACCEPT
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -p udp -m udp --dport 547 -j ACCEPT
    fi
}

# TODO: use 'DNAT' instead of '--to-ports' to support other IP
start_redsocks() {
    echo
    echo "iptables: transparent proxy non-LAN TCP/UDP traffic to port ${TP_PORT}"
    if [[ $NO4 -eq 0 ]]; then
        iptables_ -t nat -N REDSOCKS-${SUBNET_IFACE} || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 0.0.0.0/8 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 10.0.0.0/8 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 100.64.0.0/10  -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 127.0.0.0/8 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 169.254.0.0/16 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 172.16.0.0/12 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 192.168.0.0/16 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 224.0.0.0/4 -j RETURN || die
        iptables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d 255.255.255.255 -j RETURN || die
        
        iptables_ -v -t nat -A REDSOCKS-${SUBNET_IFACE} -p tcp -j REDIRECT --to-ports ${TP_PORT} || die
        iptables_ -v -t nat -A REDSOCKS-${SUBNET_IFACE} -p udp -j REDIRECT --to-ports ${TP_PORT} || die

        iptables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -j REDSOCKS-${SUBNET_IFACE} || die

        iptables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -p tcp -m tcp --dport ${TP_PORT}  -j ACCEPT || die
        iptables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -p udp -m udp --dport ${TP_PORT}  -j ACCEPT || die
    fi
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -t nat -N REDSOCKS-${SUBNET_IFACE} || die
        ip6tables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d fc00::/7 -j RETURN || die
        ip6tables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d fe80::/10 -j RETURN || die
        ip6tables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d ff00::/8 -j RETURN || die
        ip6tables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d ::1 -j RETURN || die
        ip6tables_ -t nat -A REDSOCKS-${SUBNET_IFACE} -d :: -j RETURN || die

        ip6tables_ -v -t nat -A REDSOCKS-${SUBNET_IFACE} -p tcp -j REDIRECT --to-ports ${TP_PORT} || die
        ip6tables_ -v -t nat -A REDSOCKS-${SUBNET_IFACE} -p udp -j REDIRECT --to-ports ${TP_PORT} || die

        ip6tables_ -v -t nat -I PREROUTING -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -j REDSOCKS-${SUBNET_IFACE} || die

        ip6tables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -p tcp -m tcp --dport ${TP_PORT}  -j ACCEPT || die
        ip6tables_ -v -I INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -p udp -m udp --dport ${TP_PORT}  -j ACCEPT || die   
    fi
}
stop_redsocks() {
    echo "iptables: stop transparent proxy"
    if [[ $NO4 -eq 0 ]]; then
        iptables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24  -j REDSOCKS-${SUBNET_IFACE}
        iptables_ -t nat -F REDSOCKS-${SUBNET_IFACE}
        iptables_ -t nat -X REDSOCKS-${SUBNET_IFACE}
        
        iptables_ -D INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -p tcp -m tcp --dport ${TP_PORT}  -j ACCEPT
        iptables_ -D INPUT -i ${SUBNET_IFACE} -s ${GATEWAY%.*}.0/24 -p udp -m udp --dport ${TP_PORT}  -j ACCEPT
    fi
    if [[ $IPV6 -eq 1 ]]; then
        ip6tables_ -t nat -D PREROUTING -i ${SUBNET_IFACE} -s ${PREFIX6}/64  -j REDSOCKS-${SUBNET_IFACE}
        ip6tables_ -t nat -F REDSOCKS-${SUBNET_IFACE}
        ip6tables_ -t nat -X REDSOCKS-${SUBNET_IFACE}
        
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -p tcp -m tcp --dport ${TP_PORT}  -j ACCEPT
        ip6tables_ -D INPUT -i ${SUBNET_IFACE} -s ${PREFIX6}/64 -p udp -m udp --dport ${TP_PORT}  -j ACCEPT
    fi
}
#---------------------------------------
backup_ipv6_bits() {
    mkdir "$CONFDIR/sys_6_conf_iface" || die "Failed making dir to save interface IPv6 status"
    cp  "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/disable_ipv6" \
        "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/accept_ra"     \
        "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/use_tempaddr"  \
        "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/addr_gen_mode" \
            "$CONFDIR/sys_6_conf_iface/" || die "Failed backing up interface ipv6 bits"
            
    if [[ "$SHARE_METHOD" == 'redsocks' ]] ; then
        cp "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/forwarding" \
            "$CONFDIR/sys_6_conf_iface/" || die "Failed backking up interface ipv6 bits"
    fi
}
set_ipv6_bits() {
    if [[ $IPV6 -eq 1 ]]; then
        echo 0 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/disable_ipv6"
        echo 0 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/accept_ra"
        echo 0 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/use_tempaddr"
        echo 0 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/addr_gen_mode"
    else
        echo 1 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/disable_ipv6"
    fi
}
restore_ipv6_bits() {
    if [[ -d "$CONFDIR/sys_6_conf_iface" ]]; then
        cp -f "$CONFDIR/sys_6_conf_iface/*" "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/"
    fi
}

set_interface_mac() {
    local INTERFACE
    local MAC
    
    INTERFACE=$1
    MAC=$2
    
    ip link set dev ${INTERFACE} address ${MAC} 
}

backup_interface_status() {
    # virtual wifi interface will be destroyed, so no need to save status
    
    # backup interface up or down status
    (ip link show ${SUBNET_IFACE} |grep -q "state UP") && SUBNET_IFACE_ORIGINAL_UP_STATUS=1
    
    # save interface old mac 
    #if [[ -n "$NEW_MACADDR" ]]; then 
        OLD_MACADDR=$(get_interface_mac $SUBNET_IFACE)
        #echo "Saved ${SUBNET_IFACE} old MAC address ${OLD_MACADDR} into RAM"
    #fi
    
    backup_ipv6_bits
    
    # TODO : backup ip and others
    
    # nm managing status is saved when nm_set_unmanaged()
}
restore_interface_status() {
    # virtual wifi interface will be destroyed, so no need to restore status
    # don't use [[ $VWIFI_IFACE ]] to judge, if creating virtual wifi failed, VWIFI_IFACE is empty
    [[ "$WIFI_IFACE" && "$NO_VIRT" -eq 0 ]] && return
    
    restore_ipv6_bits

    if [[ -n "$OLD_MACADDR" && "$(get_interface_mac $SUBNET_IFACE)" != "$OLD_MACADDR" ]] ; then
        echo "Restoring ${SUBNET_IFACE} to old MAC address ${OLD_MACADDR} ..."
        set_interface_mac ${SUBNET_IFACE} ${OLD_MACADDR} || echo "Failed restoring ${SUBNET_IFACE} to old MAC address ${OLD_MACADDR}" >&2
    fi
    
    nm_restore_manage
    
    [[ $SUBNET_IFACE_ORIGINAL_UP_STATUS -eq 1 ]] && ip link set up dev ${SUBNET_IFACE} && echo "Restore ${SUBNET_IFACE} to link up"
}
#---------------------------------------

kill_processes() { # for this instance
    #echo "Killing processes"
    local x  pid
    for x in $CONFDIR/*.pid; do
        # even if the $CONFDIR is empty, the for loop will assign
        # a value in $x. so we need to check if the value is a file
        if [[ -f $x ]] &&  sleep 0.3  && [[ -f $x ]]; then
            pid=$(cat $x)
            pn=$( ps -p $pid -o comm= ) 
            #echo "Killing $pid $pn ... "
            pkill -P $pid
            kill $pid 2>/dev/null && ( echo "Killed $pid $pn" && rm $x ) || echo "Failed to kill $pid $pn, it may have exited"
        fi
    done
}

_cleanup() {
    local x

    ip addr flush ${SUBNET_IFACE}
    
    rm -rf $CONFDIR
    
    ip link set down dev ${SUBNET_IFACE}
    
    if [[ $VWIFI_IFACE ]]; then # the subnet interface (virtual wifi interface) will be removed
        iw dev ${VWIFI_IFACE} del
        dealloc_vface_name $VWIFI_IFACE
    fi
    
    restore_interface_status
    
    if ! has_running_instance; then
        echo "Exiting: This is the only running instance"
        # kill common processes
        for x in $COMMON_CONFDIR/*.pid; do
            [[ -f $x ]] && kill -9 $(cat $x) && rm $x
        done
        
        rm -d $COMMON_CONFDIR/vfaces
        rm -d $COMMON_CONFDIR
        rm -d $TMPDIR
    else
        echo "Exiting: This is NOT the only running instance"
    fi
}

clean_iptables() {

    if [[ "$SHARE_METHOD" == "nat" ]]; then
        stop_nat
    elif [[ "$SHARE_METHOD" == "redsocks" ]]; then
        stop_redsocks
    fi
    
    if [[ "$DHCP_DNS" == "gateway" || "$DHCP_DNS6" == "gateway" ]]; then
        unallow_dns_port
    fi
    
    [[ "$CATCH_DNS" -eq 1 ]] && stop_catch_dns
    
    
    if [[ $NO_DNSMASQ -eq 0 ]]; then
        unallow_dhcp
    fi
    
    [[ "$BANLAN" -eq 1 ]] && stop_ban_lan
}

cleanup() {
    trap "" SIGINT SIGUSR1 SIGUSR2 EXIT SIGTERM
    echo
    echo
    echo "Doing cleanup.. "
    kill_processes
    clean_iptables  2> /dev/null
    _cleanup 2> /dev/null
    
    pgid=$(ps opgid= $$ |awk '{print $1}' )
    kill -15 -$pgid
    sleep 1 
    echo "Cleaning up done"
    #kill -9 -$pgid
}

# NOTE function die() is designed not to be used before init_trap() executed
die() { # SIGUSR2
    echo "Error occured"
    [[ -n "$1" ]] && echo -e "\nERROR: $1\n" >&2
    # send die signal to the main process
    [[ $BASHPID -ne $$ ]] && kill -USR2 $$ || cleanup
    exit 1
}

clean_exit() { # SIGUSR1
    # send clean_exit signal to the main process
    [[ $BASHPID -ne $$ ]] && kill -USR1 $$ || cleanup
    exit 0
}

init_trap(){
    trap "cleanup" EXIT
    trap "clean_exit" SIGINT SIGUSR1 SIGTERM
    trap "die" SIGUSR2
}
init_conf_dirs() {
    mkdir -p "$TMPDIR" || die "Couldn't make linux-router's temporary dir"
    chmod 755 "$TMPDIR" 2>/dev/null
    cd "$TMPDIR" || die "Couldn't change directory to linux-router's temporary path"

    CONFDIR="$(mktemp -d $TMPDIR/lnxrouter.${TARGET_IFACE}.conf.XXXXXX)" || die "Instance couldn't make config dir" # config dir for one instance
    chmod 755 "$CONFDIR"
    #echo "Config dir: $CONFDIR"
    echo $$ > "$CONFDIR/pid"

    COMMON_CONFDIR="$TMPDIR/lnxrouter_common.conf" # config dir for all instances
    mkdir -p "$COMMON_CONFDIR"
}

#== functions to deal with running instances

list_running_conf() {
    local x
    for x in $TMPDIR/lnxrouter.*; do
        if [[ -f $x/pid && -f $x/subn_iface && -d /proc/$(cat $x/pid) ]]; then
            echo "$x"
        fi
    done
}

list_running() {
    local IFACE subn_iface x
    for x in $(list_running_conf); do
        IFACE=${x#*.}
        IFACE=${IFACE%%.*}
        subn_iface=$(cat $x/subn_iface)

        if [[ $IFACE == $subn_iface ]]; then
            echo $(cat $x/pid) $IFACE
        else
            echo $(cat $x/pid) $IFACE '('$(cat $x/subn_iface)')'
        fi
    done
}

get_subn_iface_from_pid() {
    list_running | awk '{print $1 " " $NF}' | tr -d '\(\)' | grep -E "^${1} " | cut -d' ' -f2
}

get_pid_from_subn_iface() {
    list_running | awk '{print $1 " " $NF}' | tr -d '\(\)' | grep -E " ${1}$" | cut -d' ' -f1
}

get_confdir_from_pid() {
    local IFACE x
    for x in $(list_running_conf); do
        if [[ $(cat $x/pid) == "$1" ]]; then
            echo "$x"
            break
        fi
    done
}

#======================================================

print_clients_from_leases() {  # MAC|IP|HOST|lease
    local LEASE_FILE="$1"
    local FILEC
    local line
    local LEASEstr LEASEstamp
    
    FILEC="$(cat "$LEASE_FILE" | grep -v -E "^duid\b" | sed -r '/^\s*$/d' )"

    # TODO: duid is somewhat related to ipv6. I don't know about it. Not sure excluding it miss some info or not
    echo "$FILEC" | while read line
    do
        #echo aa$line
        LEASEstamp="$(echo "$line" | awk '{print $1}')"
        MAC="$(echo "$line" | awk '{print $2}')"
        IP="$(echo "$line" | awk '{print $3}'  | sed 's/\[//g' | sed 's/\]//g')"
        HOST="$(echo "$line" | awk '{print $4}' | sed 's/*/?/g' | sed 's/|/_/g' | sed 's/ /_/g' )"
        
        if [[ -n "$MAC" ]]; then
            LEASEstr="$(date -d @${LEASEstamp} +%m-%d_%X)"
            
            echo "$MAC|$IP|$HOST|lease_$LEASEstr"
        fi
    done
    
}
print_interface_neighbors_via_iproute() {  # MAC|IP|_|STATUS 
    local IFACE=$1
    
    local line
    
    ip n | grep -E "\bdev $IFACE\b" | sed 's/ /|/g' | while read line
    do
        local MAC IP STATUS
        
        IP="$(echo $line | awk -F'|' '{print $1}')"
        
        if [[ "$(echo $line | awk -F'|' '{print $4}')" == "lladdr" ]]; then # has mac
            # if has mac, $4="lladdr" and $5=macaddress and $6+=status
            MAC="$(echo $line | awk -F'|' '{print $5}')"
            STATUS="$(echo $line | awk -F'|' '$1="";$2="";$3="";$4="";$5="";{print}' | awk '{$1=$1;print}'| sed 's/ /,/g')"
        else # no mac 
            # if no mac, $4="" and $5+=status
            MAC="?"
            STATUS="$(echo $line | awk -F'|' '$1="";$2="";$3="";$4="";{print}' | awk '{$1=$1;print}' | sed 's/ /,/g')"
        fi
        if [[ -n "$IP" && ( "$MAC" != "?" || "$STATUS" != "FAILED" ) ]]; then
            echo "$MAC|$IP|?|$STATUS"
        fi
    done
}
print_interface_neighbors_via_iw() {  # MAC|_|_|signal  
    local IFACE=$1
    local MAC SIGNAL
    iw dev $IFACE station dump | awk '($1 ~ /Station$/) {print $2}' | while read MAC
    do
        if [[ -n "$MAC" ]]; then
            SIGNAL="$(iw dev $IFACE station get $MAC | grep "signal:" | awk '{print $2}')"
            echo "${MAC}|?|?|${SIGNAL}_dBm"
        fi
    done
}

list_clients() { # passive mode. (use 'arp-scan' or 'netdiscover' if want active mode)
    local IFACE pid
    local CONFDIR
    
    local output=""
    # If number (PID) is given, get the associated wifi iface
    if [[ "$1" =~ ^[1-9][0-9]*$ ]]; then
        pid="$1"
        IFACE=$(get_subn_iface_from_pid "$pid")
        if [[ -z "$IFACE" ]] ; then
            echo "'$pid' is not the pid of a running $PROGNAME instance." >&2 
            exit 1
        fi
    else # non-number given
        IFACE="$1"
        if ( ! is_interface $IFACE ) ; then
            echo "'$IFACE' is not an interface or PID" >&2
            exit 1
        fi
        pid=$(get_pid_from_subn_iface "$IFACE")
        if [[ -n "$pid" ]] ; then  # if this interface is hosted by us
            CONFDIR=$(get_confdir_from_pid "$pid")
            output="$(print_clients_from_leases "$CONFDIR/dnsmasq.leases" )"
        else    # this interface NOT hosted by us
            echo "Tip: '$IFACE' is not an interface hosted by $PROGNAME" >&2
        fi
    fi
    output="$(echo "$output" ; print_interface_neighbors_via_iw $IFACE) "
    output="$(echo "$output" ; print_interface_neighbors_via_iproute $IFACE)"
    
    output="$(echo "$output" | sort -k 1 -k 2 -t '|' | uniq | sed -r '/^\s*$/d')"

    echo "$IFACE ($(get_interface_mac $IFACE)) neighbors:"
    
    local fmt="%-19s%-41s%-20s%s" # string length: MAC 17, ipv4 15, ipv6 39, hostname ?
    printf "$fmt\n"  "MAC" "IP" "HOSTNAME" "INFO"
    
    local line
    echo "$output"| while read line
    do
        if [[ -n "$line" ]]; then
            echo "$line" | awk -F'|' "{printf \"$fmt\n\",\$1,\$2,\$3,\$4}"
        fi
    done
    # TODO : merge same mac and same ip line
}

has_running_instance() {
    local PID x

    for x in $TMPDIR/lnxrouter.*; do
        if [[ -f $x/pid ]]; then
            PID=$(cat $x/pid)
            if [[ -d /proc/$PID ]]; then
                return 0
            fi
        fi
    done

    return 1
}

is_running_pid() {
    list_running | grep -E "^${1} " > /dev/null 2>&1
}

send_stop() {
    local x

    # send stop signal to specific pid
    if is_running_pid $1; then
        kill -USR1 $1
        return
    fi

    # send stop signal to specific interface
    for x in $(list_running | grep -E " \(?${1}( |\)?\$)" | cut -f1 -d' '); do
        kill -USR1 $x
    done
}


## ========================================================
## ========================================================
# decide linux-router's global temporary path for all instances
# this is different and should be before config-saving dir. The latter is for one instance
decide_tmpdir(){
    local TMPD
    if [[ -d /dev/shm ]]; then
        TMPD=/dev/shm
    elif [[ -d /run/shm ]]; then
        TMPD=/run/shm
    else
        TMPD=/tmp
    fi
    #TMPDIR=$TMPD/lnxrouter_tmp
    echo "$TMPD/lnxrouter_tmp"
}

#======

check_other_functions(){
    if [[ $LIST_RUNNING -eq 1 ]]; then
        echo -e "List of running $PROGNAME instances:\n"
        list_running
        exit 0
    fi

    if [[ -n "$LIST_CLIENTS_ID" ]]; then
        list_clients "$LIST_CLIENTS_ID"
        exit 0
    fi

    ##### root test ##### NOTE above don't require root ##########
    if [[ $(id -u) -ne 0 ]]; then
        echo "You must run it as root." >&2
        exit 1
    fi
    ###### NOTE below require root ##########

    if [[ -n "$STOP_ID" ]]; then
        echo "Trying to kill $PROGNAME instance associated with $STOP_ID..."
        send_stop "$STOP_ID"
        exit 0
    fi
}


daemonizing_check(){
    if [[ $DAEMONIZE -eq 1 && $RUNNING_AS_DAEMON -eq 0 ]]; then
        echo "Running as Daemon..."
        # run a detached lnxrouter
        RUNNING_AS_DAEMON=1 setsid "$0" "${ARGS[@]}" &
        exit 0
    fi
}

#============================
check_wifi_settings() {

    if ! ( which iw > /dev/null 2>&1 && iw dev $WIFI_IFACE info > /dev/null 2>&1 ); then
        echo "WARN: Can't use 'iw' to operate interfce '$WIFI_IFACE', trying 'iwconfig' (not as good as 'iw') ..." >&2
        USE_IWCONFIG=1
    fi
    
    if [[ $USE_IWCONFIG -eq 1 ]]; then
        if ! (which iwconfig > /dev/null 2>&1 && iwconfig $WIFI_IFACE > /dev/null 2>&1); then
            echo "ERROR: Can't use 'iwconfig' to operate interfce '$WIFI_IFACE'" >&2
            exit 1
        fi
    fi
    
    if [[ $FREQ_BAND != 2.4 && $FREQ_BAND != 5 ]]; then
        echo "ERROR: Invalid frequency band" >&2
        exit 1
    fi

    if [[ $CHANNEL == default ]]; then
        if [[ $FREQ_BAND == 2.4 ]]; then
            CHANNEL=1
        else
            CHANNEL=36
        fi
    fi

    if [[ $FREQ_BAND != 5 && $CHANNEL -gt 14 ]]; then
        echo "Channel number is greater than 14, assuming 5GHz frequency band"
        FREQ_BAND=5
    fi

    if ! can_be_ap ${WIFI_IFACE}; then
        echo "ERROR: Your adapter does not support AP (master) mode" >&2
        exit 1
    fi

    if ! can_be_sta_and_ap ${WIFI_IFACE}; then
        if is_interface_wifi_connected ${WIFI_IFACE}; then
            echo "ERROR: Your adapter can not be a station (i.e. be connected) and an AP at the same time" >&2
            exit 1
        elif [[ $NO_VIRT -eq 0 ]]; then
            echo "WARN: Your adapter does not fully support AP virtual interface, enabling --no-virt" >&2
            NO_VIRT=1
        fi
    fi

    HOSTAPD=$(which hostapd)

    if [[ $(get_adapter_kernel_module ${WIFI_IFACE}) =~ ^(8192[cd][ue]|8723a[sue])$ ]]; then
        if ! strings "$HOSTAPD" | grep -m1 rtl871xdrv > /dev/null 2>&1; then
            echo "ERROR: You need to patch your hostapd with rtl871xdrv patches." >&2
            exit 1
        fi

        if [[ $DRIVER != "rtl871xdrv" ]]; then
            echo "WARN: Your adapter needs rtl871xdrv, enabling --driver=rtl871xdrv" >&2
            DRIVER=rtl871xdrv
        fi
    fi
    
    if [[ ${#SSID} -lt 1 || ${#SSID} -gt 32 ]]; then
        echo "ERROR: Invalid SSID length ${#SSID} (expected 1..32)" >&2
        exit 1
    fi

    if [[ $USE_PSK -eq 0 ]]; then
        if [[ ${#PASSPHRASE} -gt 0 && ${#PASSPHRASE} -lt 8 ]] || [[ ${#PASSPHRASE} -gt 63 ]]; then
            echo "ERROR: Invalid passphrase length ${#PASSPHRASE} (expected 8..63)" >&2
            exit 1
        fi
    elif [[ ${#PASSPHRASE} -gt 0 && ${#PASSPHRASE} -ne 64 ]]; then
        echo "ERROR: Invalid pre-shared-key length ${#PASSPHRASE} (expected 64)" >&2
        exit 1
    fi

    if [[ $(get_adapter_kernel_module ${WIFI_IFACE}) =~ ^rtl[0-9].*$ ]]; then
        if [[ $WPA_VERSION == '1' || $WPA_VERSION == '1+2' ]]; then
            echo "WARN: Realtek drivers usually have problems with WPA1, WPA2 is recommended" >&2
        fi
        echo "WARN: If AP doesn't work, read https://github.com/oblique/create_ap/blob/master/howto/realtek.md" >&2
    fi
}

check_if_new_mac_valid() {
    if ! is_unicast_macaddr "$NEW_MACADDR"; then
        echo "ERROR: The first byte of MAC address (${NEW_MACADDR}) must be even" >&2
        exit 1
    fi

    if [[ $(get_all_mac_in_system | grep -c ${NEW_MACADDR}) -ne 0 ]]; then
        echo "WARN: MAC address '${NEW_MACADDR}' already exists" >&2
    fi
}

decide_target_interface() {
    # TARGET_IFACE is a existing physical interface
    if [[ "$CONN_IFACE" ]]; then
        echo "$CONN_IFACE"
    elif [[ "$WIFI_IFACE" ]]; then
        echo "$WIFI_IFACE"
    else
        echo "No target interface specified"  >&2
        return 1
    fi
}

decide_ip_addresses() {
    if [[ ! -n $GATEWAY ]]; then
        GATEWAY="$(generate_random_ip4)"
        echo "Use random LAN IPv4 address $GATEWAY"
    elif [[ ! "$GATEWAY" =~ "." ]]; then
        GATEWAY="192.168.${GATEWAY}.1"
    fi

    if [[ $IPV6 -eq 1 && ! -n $PREFIX6 ]]; then
        PREFIX6="$(generate_random_lan_ip6_prefix)"
        echo "Use random LAN IPv6 address ${PREFIX6}${IID6}"
    elif [[ ! "$PREFIX6" =~ ":" ]]; then
        PREFIX6="fd00:0:0:${PREFIX6}::"
    fi
    if [[ $IPV6 -eq 1 ]]; then
        GATEWAY6="${PREFIX6}${IID6}"
    fi
}

prepare_wifi_interface() {
    if [[ $USE_IWCONFIG -eq 0 ]]; then
        iw dev ${WIFI_IFACE} set power_save off
    fi
    
    if [[ $NO_VIRT -eq 0 ]]; then
    ## Will generate virtual wifi interface
        if is_interface_wifi_connected ${WIFI_IFACE}; then
            WIFI_IFACE_FREQ=$(iw dev ${WIFI_IFACE} link | grep -i freq | awk '{print $2}')
            WIFI_IFACE_CHANNEL=$(ieee80211_frequency_to_channel ${WIFI_IFACE_FREQ})
            echo "${WIFI_IFACE} already in channel ${WIFI_IFACE_CHANNEL} (${WIFI_IFACE_FREQ} MHz)"
            if is_5ghz_frequency $WIFI_IFACE_FREQ; then
                FREQ_BAND=5
            else
                FREQ_BAND=2.4
            fi
            if [[ $WIFI_IFACE_CHANNEL -ne $CHANNEL ]]; then
                echo "Channel fallback to ${WIFI_IFACE_CHANNEL}"
                CHANNEL=$WIFI_IFACE_CHANNEL
            else
                echo
            fi
        fi

        echo "Creating a virtual WiFi interface... "
        VWIFI_IFACE=$(alloc_new_vface_name)
        if iw dev ${WIFI_IFACE} interface add ${VWIFI_IFACE} type __ap; then
            # Successfully created virtual wifi interface
            # if NM running, it will give the new virtual interface a random MAC. MAC will go back after setting NM unmanaged
            sleep 2  
            echo "${VWIFI_IFACE} created"
        else
            VWIFI_IFACE=
            die "Failed creating virtual WiFi interface. Maybe your WiFi adapter does not fully support virtual interfaces. Try again with '--no-virt'"
        fi
        
        AP_IFACE=${VWIFI_IFACE}
    else # no virtual wifi interface, use wifi device interface itself
        AP_IFACE=${WIFI_IFACE}
    fi
}

decide_subnet_interface() {
    if [[ $WIFI_IFACE ]]; then
        echo "${AP_IFACE}"
    else
        echo "${TARGET_IFACE}"
    fi
}

dealwith_mac() {
    local VMAC
    
    if [[ -n "$NEW_MACADDR" ]] ; then  # user choose to set subnet mac 

        echo "Setting ${SUBNET_IFACE} new MAC address ${NEW_MACADDR} ..."
        set_interface_mac ${SUBNET_IFACE} ${NEW_MACADDR} || die "Failed setting new MAC address"
        
    elif [[ $VWIFI_IFACE ]]; then # user didn't choose to set mac, but using virtual wifi interface

        VMAC=$(get_new_macaddr_according_to_existing ${WIFI_IFACE})
        if [[ "$VMAC" ]]; then
            echo "Assigning MAC address $VMAC to virtual interface $VWIFI_IFACE according to $WIFI_IFACE ..."
            set_interface_mac $VWIFI_IFACE $VMAC
        fi
    fi
}

write_hostapd_conf() {  
    cat <<- EOF > "$CONFDIR/hostapd.conf"
		beacon_int=100
		ssid=${SSID}
		interface=${AP_IFACE}
		driver=${DRIVER}
		channel=${CHANNEL}
		ctrl_interface=$CONFDIR/hostapd_ctrl
		ctrl_interface_group=0
		ignore_broadcast_ssid=$HIDDEN
		ap_isolate=$ISOLATE_CLIENTS
	EOF

    if [[ -n "$COUNTRY" ]]; then
        cat <<- EOF >> "$CONFDIR/hostapd.conf"
			country_code=${COUNTRY}
			ieee80211d=1
		EOF
    fi

    if [[ $FREQ_BAND == 2.4 ]]; then
        echo "hw_mode=g" >> "$CONFDIR/hostapd.conf"
    else
        echo "hw_mode=a" >> "$CONFDIR/hostapd.conf"
    fi

    if [[ $MAC_FILTER -eq 1 ]]; then
        cat <<- EOF >> "$CONFDIR/hostapd.conf"
			macaddr_acl=${MAC_FILTER}
			accept_mac_file=${MAC_FILTER_ACCEPT}
		EOF
    fi

    if [[ $IEEE80211N -eq 1 ]]; then
        cat <<- EOF >> "$CONFDIR/hostapd.conf"
			ieee80211n=1
			ht_capab=${HT_CAPAB}
		EOF
    fi

    if [[ $IEEE80211AC -eq 1 ]]; then
        echo "ieee80211ac=1" >> "$CONFDIR/hostapd.conf"
    fi

    if [[ -n "$VHT_CAPAB" ]]; then
        echo "vht_capab=${VHT_CAPAB}" >> "$CONFDIR/hostapd.conf"
    fi

    if [[ $IEEE80211N -eq 1 ]] || [[ $IEEE80211AC -eq 1 ]]; then
        echo "wmm_enabled=1" >> "$CONFDIR/hostapd.conf"
    fi

    if [[ -n "$PASSPHRASE" ]]; then
        [[ "$WPA_VERSION" == "1+2" ]] && WPA_VERSION=3
        if [[ $USE_PSK -eq 0 ]]; then
            WPA_KEY_TYPE=passphrase
        else
            WPA_KEY_TYPE=psk
        fi
        cat <<- EOF >> "$CONFDIR/hostapd.conf"
			wpa=${WPA_VERSION}
			wpa_${WPA_KEY_TYPE}=${PASSPHRASE}
			wpa_key_mgmt=WPA-PSK
			wpa_pairwise=CCMP
			rsn_pairwise=CCMP
		EOF
    else
        echo "WARN: Wifi is not protected by password" >&2
    fi
    chmod 600 "$CONFDIR/hostapd.conf"
}

write_dnsmasq_conf() {
    if grep "^nobody:" /etc/group >/dev/null 2>&1 ; then
        NOBODY_GROUP="nobody"
    else
        NOBODY_GROUP="nogroup"
    fi
    
    mkfifo "$CONFDIR/dnsmasq.log" || die "Failed creating pipe file for dnsmasq"
    chown nobody "$CONFDIR/dnsmasq.log" || die "Failed changing dnsmasq log file owner"
    cat "$CONFDIR/dnsmasq.log" & 
    
    cat <<- EOF > "$CONFDIR/dnsmasq.conf"
		user=nobody
		group=$NOBODY_GROUP
		bind-dynamic
		listen-address=${GATEWAY}
		interface=$SUBNET_IFACE
		except-interface=lo
		no-dhcp-interface=lo
		dhcp-range=${GATEWAY%.*}.10,${GATEWAY%.*}.250,255.255.255.0
		dhcp-option-force=option:router,${GATEWAY}
		#log-dhcp
		log-facility=$CONFDIR/dnsmasq.log
		bogus-priv
		domain-needed
	EOF
    # 'log-dhcp'(Extra logging for DHCP) shows too much logs.
    # if use '-d', 'log-facility' should = /dev/null
    if [[ $SHARE_METHOD == "none" ]]; then    
        echo "no-resolv"  >> "$CONFDIR/dnsmasq.conf"
        echo "no-poll" >> "$CONFDIR/dnsmasq.conf"
    fi
    if [[ "$DHCP_DNS" != "no" ]]; then
        if [[ "$DHCP_DNS" == "gateway" ]]; then
            dns_offer="$GATEWAY"
        else
            dns_offer="$DHCP_DNS"
        fi
        echo "dhcp-option-force=option:dns-server,${dns_offer}" >> "$CONFDIR/dnsmasq.conf"
    fi
    
    if [[ ! "$dnsmasq_NO_DNS" -eq 0 ]]; then
        echo "port=0"  >> "$CONFDIR/dnsmasq.conf"
    fi

    [[ -n "$MTU" ]] && echo "dhcp-option-force=option:mtu,${MTU}" >> "$CONFDIR/dnsmasq.conf"
    [[ $ETC_HOSTS -eq 0 ]] && echo no-hosts >> "$CONFDIR/dnsmasq.conf"
    [[ -n "$ADDN_HOSTS" ]] && echo "addn-hosts=${ADDN_HOSTS}" >> "$CONFDIR/dnsmasq.conf"
    if [[ "$THISHOSTNAME" ]]; then
        [[ "$THISHOSTNAME" == "-" ]] && THISHOSTNAME="$(cat /etc/hostname)"
        echo "interface-name=$THISHOSTNAME,$SUBNET_IFACE" >> "$CONFDIR/dnsmasq.conf"
    fi
    if [[ ! "$SHOW_DNS_QUERY" -eq 0 ]]; then
        echo log-queries=extra >> "$CONFDIR/dnsmasq.conf"
    fi
    
    if [[ $DNS ]]; then
        DNS_count=$(echo "$DNS" | awk -F, '{print NF}')
        for (( i=1;i<=DNS_count;i++ )); do
            sep_ip_port "$(echo $DNS | cut -d, -f$i)" DNS_IP DNS_PORT
            [[ "$DNS_PORT" ]] && DNS_PORT_D="#$DNS_PORT"
            echo "server=${DNS_IP}${DNS_PORT_D}" >> "$CONFDIR/dnsmasq.conf"
        done
        
        cat <<- EOF >> "$CONFDIR/dnsmasq.conf"
			no-resolv
			no-poll
		EOF
    fi
    if [[ $IPV6 -eq 1 ]];then
        cat <<- EOF  >> "$CONFDIR/dnsmasq.conf"
			listen-address=${GATEWAY6}
			enable-ra
			#quiet-ra
			dhcp-range=interface:${SUBNET_IFACE},::,::ffff:ffff:ffff:ffff,constructor:${SUBNET_IFACE},ra-stateless,64
		EOF
        if [[ "$DHCP_DNS6" != "no" ]]; then
            if [[ "$DHCP_DNS6" == "gateway" ]]; then
                dns_offer6="[$GATEWAY6]"
            else
                dns_offer6="$DHCP_DNS6"
            fi
            echo "dhcp-option=option6:dns-server,${dns_offer6}" >> "$CONFDIR/dnsmasq.conf"
        fi
    fi
}

run_wifi_ap_processes() {
    if [[ $NO_HAVEGED -eq 0 ]]; then
        haveged_watchdog &
        HAVEGED_WATCHDOG_PID=$!
        echo "$HAVEGED_WATCHDOG_PID" > "$CONFDIR/haveged_watchdog.pid"
        echo
        echo "haveged_watchdog PID: $HAVEGED_WATCHDOG_PID" 
    fi

    # start access point
    #echo "hostapd command-line interface: hostapd_cli -p $CONFDIR/hostapd_ctrl"
    # start hostapd (use stdbuf when available for no delayed output in programs that redirect stdout)
    STDBUF_PATH=`which stdbuf`
    if [ $? -eq 0 ]; then
        STDBUF_PATH=$STDBUF_PATH" -oL"
    fi
    echo 
    echo "Starting hostapd"
    
    if which complain > /dev/null 2>&1; then
        complain hostapd
    fi
    
    # hostapd '-P' works only when use '-B' (run in background)
    $STDBUF_PATH hostapd $HOSTAPD_DEBUG_ARGS -P "$CONFDIR/hostapd.pid" "$CONFDIR/hostapd.conf"  &
    HOSTAPD_PID=$!
    echo "$HOSTAPD_PID" > "$CONFDIR/hostapd.pid"
    echo "hostapd PID: $HOSTAPD_PID"
    #while [[ ! -f $CONFDIR/hostapd.pid ]]; do
    #    sleep 1
    #done
    #echo -n "hostapd PID: " ; cat $CONFDIR/hostapd.pid
    pid_watchdog $HOSTAPD_PID 10 "hostapd failed" &
    sleep 3
}

start_dnsmasq() {
    echo 
    echo "Starting dnsmasq"
    
    if which complain > /dev/null 2>&1; then
        # openSUSE's apparmor does not allow dnsmasq to read files.
        # remove restriction.
        complain dnsmasq
    fi
    
    # Using '-d'(no daemon) dnsmasq will not turn into 'nobody'
    # '-x' works only when no '-d'
    dnsmasq  -k -C "$CONFDIR/dnsmasq.conf" -x "$CONFDIR/dnsmasq.pid" -l "$CONFDIR/dnsmasq.leases" & 
    #####DNSMASQ_PID=$!         # only when with '-d'
    ######echo "dnsmasq PID: $DNSMASQ_PID"      # only when with '-d'
    i=0; while [[ ! -f "$CONFDIR/dnsmasq.pid" ]]; do
        sleep 1
        i=$((i + 1))
        if [[ $i -gt 10 ]]; then die "Couldn't get dnsmasq PID" ; fi
    done
    DNSMASQ_PID="$(cat "$CONFDIR/dnsmasq.pid" )"
    echo  "dnsmasq PID: $DNSMASQ_PID" 
    ######(wait $DNSMASQ_PID ; die "dnsmasq failed") &  # wait can't deal with non-child
    pid_watchdog $DNSMASQ_PID 9 "dnsmasq failed" &
    sleep 2
}

check_rfkill_unblock_wifi() {
    local PHY
    if which rfkill > /dev/null 2>&1 ; then
        PHY=$(get_interface_phy_device ${SUBNET_IFACE})
        [[ -n $PHY ]] && rfkill unblock $(rfkill | grep $PHY | awk '{print $1}') >/dev/null 2>&1
    fi
}

#=========== Above are functions ======================
#=========== Executing begin ==============================

# if empty option, show usage and exit 
check_empty_option "$@"

# TODO: are some global variables are still defined in those following code?
define_global_variables

ARGS=( "$@" )

parse_user_options "$@"
# TODO: detect user option conflict

# check if networkManager running
NM_RUNNING="$(is_nm_running)"

TMPDIR="$(decide_tmpdir)"

# if user choose to deal with running instances, will output some info then exit after this 
# NOTE above don't require root
check_other_functions 
# NOTE below require root

# if user choose to daemonize, will start new background process and exit this 
daemonizing_check

# check if wifi will work on this system and user settings
[[ $WIFI_IFACE ]] && check_wifi_settings

[[ -n "$NEW_MACADDR" ]] && check_if_new_mac_valid # check NEW_MACADDR. will exit if not valid

# checks finished

## ===== Above don't echo anything if no warning or error====================
## ========================================================
phead
echo "PID: $$"

TARGET_IFACE="$(decide_target_interface)" || exit 1 # judge wired (-i CONN_IFACE) or wireless hotspot (--ap $WIFI_IFACE)
echo "Target interface is ${TARGET_IFACE} ($(get_interface_mac $TARGET_IFACE))"
# TODO: show interface type, device model and pci/usb id (hwdata  pci.ids), current driver

if [[ "$MAC_USE_RANDOM" -eq 1 ]] ; then
    NEW_MACADDR="$(generate_random_mac)"
    echo "Use random MAC address $NEW_MACADDR"
fi

decide_ip_addresses # ip 4 & 6 lan addresses

# if user choose to make DHCP to tell clients to use other DNS, we don't have to serve DNS
[[ $DHCP_DNS != 'gateway' && $DHCP_DNS6 != 'gateway' ]] && dnsmasq_NO_DNS=1

#===========================================================
#==== begin to do some change on config files and system===

init_trap
# NOTE function die() is designed not to be used before init_trap() executed

init_conf_dirs #   CONFDIR  , COMMON_CONFDIR  . make dir

[[ $WIFI_IFACE ]] && prepare_wifi_interface # this will create virtual ap interface (if needed) and set VWIFI_IFACE and AP_IFACE (if success)

SUBNET_IFACE="$(decide_subnet_interface)"  # SUBNET_IFACE can be TARGET_IFACE (wired) or AP_IFACE (ap) .this is after prepare_wifi_interface()
echo "$SUBNET_IFACE" > "$CONFDIR/subn_iface"

# if virtual wifi interface, will be destroyed, so only need to save status when not
[[ -z $VWIFI_IFACE ]] && backup_interface_status

# TODO: should these 2 before calling prepare_wifi_interface ? in check_wifi_settings() ?
# set iw country code
if [[ $WIFI_IFACE && -n "$COUNTRY" && $USE_IWCONFIG -eq 0 ]]; then
    iw reg set "$COUNTRY" || die "Failed setting country code"
fi

# judge channel availability after changing country code
if [[ $WIFI_IFACE ]] ; then
    can_transmit_to_channel ${AP_IFACE} ${CHANNEL} || die "Your adapter can not transmit to channel ${CHANNEL}, frequency band ${FREQ_BAND}GHz."
fi

[[ $WIFI_IFACE ]] && write_hostapd_conf
#===================================================
#===================================================

# set interface unmanaged by networkManager
if [[ $NM_RUNNING -eq 1 ]] && nm_knows $TARGET_IFACE; then # if nm knows target iface, should know subnet iface too. but need to wait until nm finds subnet iface (waiting code is in nm_set_unmanaged()
    nm_set_unmanaged ${SUBNET_IFACE} # will write NM_UNM_LIST
fi

[[ $NO_DNSMASQ -eq 0 ]] && write_dnsmasq_conf
#===========================

# initialize subnet interface
# take subnet interface down first
ip link set down dev ${SUBNET_IFACE} || die "Failed setting ${SUBNET_IFACE} down"
# flush old IPs of subnet interface
ip addr flush ${SUBNET_IFACE} || die "Failed flush ${SUBNET_IFACE} IP"

dealwith_mac # setting MAC should be after setting NM unmanaged

[[ $WIFI_IFACE ]] && check_rfkill_unblock_wifi

# bring subnet interface up
ip link set up dev ${SUBNET_IFACE} || die "Failed bringing ${SUBNET_IFACE} up"

# hostapd , haveged
[[ $WIFI_IFACE ]] && run_wifi_ap_processes

# add ipv4 address to subnet interface
ip -4 addr add ${GATEWAY}/24 broadcast ${GATEWAY%.*}.255 dev ${SUBNET_IFACE} || die "Failed setting ${SUBNET_IFACE} IPv4 address"

set_ipv6_bits

# add ipv6 address to subnet interface
if [[ $IPV6 -eq 1 ]] ; then
    ip -6 addr add ${GATEWAY6}/64  dev ${SUBNET_IFACE} || die "Failed setting ${SUBNET_IFACE} IPv6 address"
fi

check_iptables

# enable Internet sharing
if [[ "$SHARE_METHOD" == "none" ]]; then

    echo "No Internet sharing"
    
    [[ "$BANLAN" -eq 1 ]] && start_ban_lan
    
elif [[ "$SHARE_METHOD" == "nat" ]]; then

    [[ "$INTERNET_IFACE" && "$dnsmasq_NO_DNS" -eq 0 ]] && echo -e "\nWARN: You specified Internet interface but this host is providing local DNS, queries may leak to other interfaces!!!\n" >&2
    
    start_nat
    
    [[ "$BANLAN" -eq 1 ]] && start_ban_lan
    
    echo 1 > "/proc/sys/net/ipv4/ip_forward" || die "Failed enabling system ipv4 forwarding"
    
    if [[ $IPV6 -eq 1 ]]; then
        echo 1 > "/proc/sys/net/ipv6/conf/all/forwarding" || die "Failed enabling system ipv6 forwarding"
    fi
    
    # to enable clients to establish PPTP connections we must
    # load nf_nat_pptp module
    modprobe nf_nat_pptp > /dev/null 2>&1 && echo "Loaded kernel module nf_nat_pptp"
    
elif [[ "$SHARE_METHOD" == "redsocks" ]]; then

    if [[ $IPV6 -eq 1 ]]; then
        echo 1 > "/proc/sys/net/ipv6/conf/$SUBNET_IFACE/forwarding" || die "Failed enabling $SUBNET_IFACE ipv6 forwarding" # to set NA router bit
    fi
    
    [[ "$dnsmasq_NO_DNS" -eq 0 && ! $DNS ]] &&  echo -e "\nWARN: You are using in transparent proxy mode but this host is providing local DNS, this may cause privacy leak !!!\n" >&2

    [[ "$BANLAN" -eq 1 ]] && start_ban_lan
    
    start_redsocks
fi

# start dhcp + dns (optional)

# allow dns port input even if we don't run dnsmasq
# user can serve their own dns server
[[ "$DHCP_DNS" == "gateway" || "$DHCP_DNS6" == "gateway" ]] && allow_dns_port

[[ "$CATCH_DNS" -eq 1 ]] && start_catch_dns

[[ $NO_DNSMASQ -eq 0 ]] && ( allow_dhcp ; start_dnsmasq )

echo 
echo "== Setting up completed, now linux-router is working =="

#============================================================
#============================================================
#============================================================

show_qr() {
    local T S P H
    S="$SSID"
    if [[ -n "$PASSPHRASE" ]]; then
        T="WPA"
        P="$PASSPHRASE"
    else
        T="nopass"
    fi
    [[ "$HIDDEN" -eq 1 ]] && H="true"
    echo "Scan QR code on phone to connect to WiFi"
    qrencode -m 2 -t ANSIUTF8 "WIFI:T:${T};S:${S};P:${P};H:${H};"
    echo "Use this command to save QR code to image file:"
    echo "    qrencode -m 2 -o <file> \"WIFI:T:${T};S:${S};P:${P};H:${H};\""
    echo
}

[[ "$QR" -eq 1 ]] && show_qr

# need loop to keep this script running
bash -c "while :; do sleep 8000 ; done " &
KEEP_RUNNING_PID=$!
echo "$KEEP_RUNNING_PID" > "$CONFDIR/keep_running.pid"
wait $KEEP_RUNNING_PID

clean_exit