#!/bin/bash
#
# Wifi Hotspot app for YunoHost
# Copyright (C) 2015 Julien Vaubourg <julien@vaubourg.com>
# Contribute at https://github.com/labriqueinternet/hotspot_ynh
#
# 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/>.

source /usr/share/yunohost/helpers

# Functions
## State functions

has_ip6delegatedprefix() {
    [[ -n "${ip6_net}" ]] && [[ "${ip6_net}" != "none" ]]
}

ip6addrfromdelegatedprefix() {
    echo "${ip6_net}1"
}

is_nat_set() {
    local gateway_interface=${1}
    iptables -w -nvt nat -L POSTROUTING | grep MASQUERADE | grep -q "${gateway_interface}"
}

is_ip4nataddr_set() {
    ip address show dev "${wifi_device}" 2>/dev/null | grep -q "${ip4_nat_prefix}.1/24"
}

is_ip6addr_set() {
    ip address show dev "${wifi_device}" 2>/dev/null | grep -q "$(ip6addrfromdelegatedprefix)/64"
}

is_ip6firewall_set() {
    ip6tables -w -nvL FORWARD | grep DROP | grep -q "${wifi_device}"
}

is_forwarding_set() {
    local ip6=$(sysctl net.ipv6.conf.all.forwarding | awk '{ print $NF; }')
    local ip4=$(sysctl net.ipv4.conf.all.forwarding | awk '{ print $NF; }')

    [[ "${ip6}" -eq 1 ]] && [[ "${ip4}" -eq 1 ]]
}

is_dhcpd6_running() {
    [[ -e "/run/dnsmasq/dnsmasq-dhcpdv6-$app.pid" ]] && ps -p $(cat "/run/dnsmasq/dnsmasq-dhcpdv6-$app.pid") > /dev/null
}

is_dhcpd4_running() {
    [[ -e "/run/dnsmasq/dnsmasq-dhcpdv4-$app.pid" ]] && ps -p $(cat "/run/dnsmasq/dnsmasq-dhcpdv4-$app.pid") > /dev/null
}

is_hostapd_running() {
    systemctl is-active "hostapd@${app}" &>/dev/null
}

is_other_hostapd_running() {
    other_hostapd_services=$(systemctl list-units --state=running hostapd@*.service | grep -v "^hostapd@$app.service")

    [[ -n "${other_hostapd_service}" ]]
}

is_running() {
    if has_ip6delegatedprefix; then
        if ! is_ip6addr_set; then
            return 1
        fi
        if [[ "${ip6_firewall}" -eq 1 ]] && ! is_ip6firewall_set; then
            return 1
        fi
        if ! is_dhcpd6_running; then
            return 1
        fi
    fi

    if ! is_ip4nataddr_set; then
        return 1
    fi

    if ! is_dhcpd4_running; then
        return 1
    fi

    if ! is_hostapd_running; then
        return 1
    fi

    if ! is_forwarding_set; then
        return 1
    fi

    if [[ -n ${new_gateway_interface} ]] && ! is_nat_set "${new_gateway_interface}"; then
        return 1
    fi

    return 0
}

## Setters

set_nat() {
    local gateway_interface=${1}

    iptables -w -t nat -A POSTROUTING -o "${gateway_interface}" -j MASQUERADE
}

set_ipaddr() {
    if ! is_ip4nataddr_set; then
        echo "hotspot ${wifi_device}: Set IPv4 NAT address"
        ip address add "${ip4_nat_prefix}.1/24" dev "${wifi_device}"
    fi

    if has_ip6delegatedprefix && ! is_ip6addr_set; then
        echo "hotspot ${wifi_device}: Set IPv6 address"
        ip address delete "$(ip6addrfromdelegatedprefix)/64" dev tun0 &>/dev/null
        ip address add "$(ip6addrfromdelegatedprefix)/64" dev "${wifi_device}"
    fi
}

set_ipfirewall() {
    # Set ipv6 firewalling
    if has_ip6delegatedprefix && [[ "${ip6_firewall}" -eq 1 ]] && ! is_ip6firewall_set; then
        echo "hotspot ${wifi_device}: Set IPv6 firewalling"
        ip6tables -w -A FORWARD -i "${wifi_device}" -j ACCEPT
        ip6tables -w -A FORWARD -o "${wifi_device}" -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
        ip6tables -w -A FORWARD -o "${wifi_device}" -j DROP
    fi
}

set_forwarding() {
    sysctl -w net.ipv6.conf.all.forwarding=1 >/dev/null
    sysctl -w net.ipv4.conf.all.forwarding=1 >/dev/null
}

start_dhcpd() {
    # Run DHCPv4 server
    if ! is_dhcpd4_running; then
        echo "hotspot ${wifi_device}: Start the DHCPv4 server (dnsmasq)"
        dnsmasq -C /etc/dnsmasq.$app/dhcpdv4.conf -p0 -x /run/dnsmasq/dnsmasq-dhcpdv4-$app.pid
    fi

    # Run DHCPv6 server
    if has_ip6delegatedprefix && ! is_dhcpd6_running; then
        echo "hotspot ${wifi_device}: Start the NDP and DHCPv6 server (dnsmasq)"
        dnsmasq -C /etc/dnsmasq.$app/dhcpdv6.conf -p0 -x /run/dnsmasq/dnsmasq-dhcpdv6-$app.pid
    fi
}

configure_hostapd() {
    local ethaddr=$(ip link show dev "${wifi_device}" | grep link/ether | awk -F: '{ printf "02:%s:%s:%s:%s:00", $2, $3, $4, $5 }')
    ip link set addr "${ethaddr}" dev "${wifi_device}"
}

## Unsetters

unset_nat() {
    local gateway_interface=${1}

    iptables -w -t nat -D POSTROUTING -o "${gateway_interface}" -j MASQUERADE
}

unset_ipaddr() {
    if is_ip4nataddr_set; then
        echo "hotspot ${wifi_device}: Unset IPv4 NAT address"
        ip address delete "${ip4_nat_prefix}.1/24" dev "${wifi_device}"
    fi

    if has_ip6delegatedprefix && is_ip6addr_set; then
        echo "hotspot ${wifi_device}: Unset IPv6 address"
        ip address delete "$(ip6addrfromdelegatedprefix)/64" dev "${wifi_device}"
    fi
}

unset_ipfirewall() {
    if has_ip6delegatedprefix && [[ "${ip6_firewall}" -eq 1 ]] && is_ip6firewall_set; then
        echo "hotspot ${wifi_device}: Unset IPv6 firewalling"
        ip6tables -w -D FORWARD -i "${wifi_device}" -j ACCEPT
        ip6tables -w -D FORWARD -o "${wifi_device}" -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
        ip6tables -w -D FORWARD -o "${wifi_device}" -j DROP
    fi
}

unset_forwarding() {
    sysctl -w net.ipv6.conf.all.forwarding=0 >/dev/null
    sysctl -w net.ipv4.conf.all.forwarding=0 >/dev/null
}

stop_dhcpd() {
    if is_dhcpd6_running; then
        echo "hotspot ${wifi_device}: Stop the NDP and DHCPv6 server (dnsmasq)"
        kill $(cat /run/dnsmasq/dnsmasq-dhcpdv6-$app.pid)
        rm -f /run/dnsmasq/dnsmasq-dhcpdv6-$app.pid
    fi

    if is_dhcpd4_running; then
        echo "hotspot ${wifi_device}: Stop the DHCPv4 server (dnsmasq)"
        kill $(cat /run/dnsmasq/dnsmasq-dhcpdv4-$app.pid)
        rm -f /run/dnsmasq/dnsmasq-dhcpdv4-$app.pid
    fi
}

stop_hostapd() {
    systemctl stop "hostapd@${app}"
}

if [ "$1" != restart ]; then

    # Variables

    echo -n "Retrieving Yunohost settings... "

    app=__APP__
    service_enabled=$(ynh_app_setting_get --app=$app --key=service_enabled)
    wifi_device=$(ynh_app_setting_get --app=$app --key=wifi_device)
    wifi_channel=$(ynh_app_setting_get --app=$app --key=wifi_channel)

    wifi_ssid=$(ynh_app_setting_get --app=$app --key=wifi_ssid)
    wifi_secure=$(ynh_app_setting_get --app=$app --key=wifi_secure)
    wifi_passphrase=$(ynh_app_setting_get --app=$app --key=wifi_passphrase)
    ip6_firewall=$(ynh_app_setting_get --app=$app --key=ip6_firewall)
    ip6_dns=$(ynh_app_setting_get --app=$app --key=ip6_dns)
    ip6_net=$(ynh_app_setting_get --app=$app --key=ip6_net)
    ip4_dns=$(ynh_app_setting_get --app=$app --key=ip4_dns)
    ip4_nat_prefix=$(ynh_app_setting_get --app=$app --key=ip4_nat_prefix)

    old_gateway_interface=$(ynh_app_setting_get --app=$app --key=gateway_interface)
    new_gateway_interface=$(ip route get 1.2.3.4 | awk '{ print $5; }')

    echo "OK"
fi

# Script

case "$1" in
start)
    if is_running; then
        echo "Already started"
        exit 0
    elif [[ "${service_enabled}" -eq 0 ]]; then
        echo "Not starting because hotspot service is disabled"
        exit 1
    fi

    if [[ -z "${wifi_device}" ]]; then
        echo "[FAIL] No wifi device selected. Make sure your wifi antenna is plugged-in / available and select it in the Hotspot admin"
        exit 1
    fi

    echo "[$app] Starting..."
    touch /tmp/.${service_name}-started

    # Check old state of the ipv4 NAT settings
    if [[ -n "${old_gateway_interface}" ]] && [[ "${new_gateway_interface}" != "${old_gateway_interface}" ]] && is_nat_set "${old_gateway_interface}"; then
        unset_nat "${old_gateway_interface}"
    fi

    # Set ipv4 NAT
    if [[ -n "${new_gateway_interface}" ]] && ! is_nat_set "${new_gateway_interface}"; then
        echo "Set NAT"
        set_nat "${new_gateway_interface}"
    fi

    # Set forwarding for ipv6 and ipv4
    echo "Set forwarding"
    set_forwarding

    # Run hostapd
    if ! is_hostapd_running; then
        echo "Configuring hostapd"
        configure_hostapd

        echo "Starting hostapd..."
        if ! systemctl start "hostapd@${app}"; then
            journalctl -u hostapd -n 100 --no-hostname --no-pager
            exit 1
        fi

        sleep 1
    fi

    set_ipaddr
    set_ipfirewall
    start_dhcpd

    # Update dynamic settings
    ynh_app_setting_set --app=$app --key=gateway_interface --value="${new_gateway_interface}"

    # Regen-conf dnsmasq to enable dns resolution on dnsmasq for the new interface
    yunohost tools regen-conf dnsmasq
    ;;
stop)
    echo "[$app] Stopping..."
    rm -f /tmp/.${service_name}-started

    if ! is_other_hostapd_running; then
        if [[ -n "${old_gateway_interface}" ]] && is_nat_set "${old_gateway_interface}"; then
            echo "Unset NAT"
            unset_nat "${old_gateway_interface}"
        fi
        
        echo "Unset forwarding"
        unset_forwarding
    fi

    unset_ipaddr
    unset_ipfirewall
    stop_dhcpd

    if is_hostapd_running; then
        echo "Stop hostapd"
        stop_hostapd
    fi

    # Regen-conf dnsmasq to disable dns resolution on dnsmasq for the previous interface
    yunohost tools regen-conf dnsmasq
    ;;
restart)
    $0 stop
    $0 start
    ;;
status)
    exitcode=0

    if [[ "${service_enabled}" -eq 0 ]]; then
        echo "[FAIL] Hotspot Service disabled"
        exit 1
    fi

    if [[ -z "${wifi_device}" ]]; then
        echo "[FAIL] No wifi device selected. Make sure your wifi antenna is plugged-in / available and select it in the Hotspot admin"
        exit 1
    fi

    echo "[INFO] Autodetected internet interface: ${new_gateway_interface} (last start: ${old_gateway_interface})"

    if is_nat_set "${new_gateway_interface}"; then
        echo "[ OK ] IPv4 NAT set"
    else
        if [[ -z "${new_gateway_interface}" ]]; then
            echo "[INFO] No IPv4 NAT set (no internet interface)"
        else
            echo "[FAIL] No IPv4 NAT set"
        fi
        exitcode=1
    fi

    if is_forwarding_set; then
        echo "[ OK ] IPv6/IPv4 forwarding set"
    else
        echo "[FAIL] No IPv6/IPv4 forwarding set"
        exitcode=1
    fi

    if is_hostapd_running; then
        echo "[ OK ] Hostapd is running"
    else
        echo "[FAIL] Hostapd is not running"
        exitcode=1
    fi

    if has_ip6delegatedprefix; then
        echo "[INFO] hotspot ${wifi_device}: IPv6 delegated prefix found"
        echo "[INFO] hotspot ${wifi_device}: IPv6 address computed from the delegated prefix: $(ip6addrfromdelegatedprefix)"

        if is_ip6addr_set; then
            echo "[ OK ] hotspot ${wifi_device}: IPv6 address set"
        else
            echo "[FAIL] hotspot ${wifi_device}: No IPv6 address set"
            exitcode=1
        fi

        if is_ip6firewall_set; then
            echo "[ OK ] hotspot ${wifi_device}: IPv6 firewalling set"
        else
            if [[ "${ip6_firewall}" -eq 1 ]]; then
                echo "[FAIL] hotspot ${wifi_device}: No IPv6 firewalling set"
            else
                echo "[INFO] hotspot ${wifi_device}: No IPv6 firewalling set"
            fi
            exitcode=1
        fi

        if is_dhcpd6_running; then
            echo "[ OK ] hotspot ${wifi_device}: NDP and DHCPv6 server (dnsmasq) are running"
        else
            echo "[FAIL] hotspot ${wifi_device}: NDP and DHCPv6 server (dnsmasq) are not running"
            exitcode=1
        fi
    else
        echo "[INFO] hotspot ${wifi_device}: No IPv6 delegated prefix found"
    fi

    if is_dhcpd4_running; then
        echo "[ OK ] hotspot ${wifi_device}: DHCPv4 server (dnsmasq) is running"
    else
        echo "[FAIL] hotspot ${zifi_device}: DHCPv4 (dnsmasq) is not running"
        exitcode=1
    fi

    if is_ip4nataddr_set; then
        echo "[ OK ]  hotspot ${wifi_device}: IPv4 NAT address set"
    else
        echo "[FAIL] hotspot ${wifi_device}: No IPv4 NAT address set"
        exitcode=1
    fi

    exit ${exitcode}
    ;;
*)
    echo "Usage: $0 {start|stop|restart|status}"
    exit 1
    ;;
esac

exit 0