#!/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/>.

# Functions
## State functions

has_vpnclient_app() {
    [ -e /tmp/.ynh-vpnclient-started ]
}

has_ip6delegatedprefix() {
    local i=${1}

    [[ -n "${ip6_net[${i}]}" ]] && [[ "${ip6_net[${i}]}" != "none" ]]
}

ip6addrfromdelegatedprefix() {
    local i=${1}

    echo "${ip6_net[${i}]}${i}001"
}

is_nat_set() {
    local gateway_interface=${1}

    iptables -w -nvt nat -L POSTROUTING | grep MASQUERADE | grep -q "${gateway_interface}"
}

is_ip4nataddr_set() {
    local i=${1}
    local dev=$(devfromid "${i}")

    ip address show dev "${dev}" 2>/dev/null | grep -q "${ip4_nat_prefix[${i}]}.1/24"
}

is_ip6addr_set() {
    local i=${1}
    local dev=$(devfromid "${i}")

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

is_ip6firewall_set() {
    local i=${1}
    local dev=$(devfromid "${i}")

    ip6tables -w -nvL FORWARD | grep DROP | grep -q "${dev}"
}

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() {
    local i=${1}

    ps aux | grep "dhcpdv6-ssid${i}" | grep -qv grep
}

is_dhcpd4_running() {
    local i=${1}

    ps aux | grep "dhcpdv4-ssid${i}" | grep -qv grep
}

is_hostapd_running() {
    systemctl is-active hostapd &>/dev/null
}

is_running() {
    for i in $(seq 0 $((${multissid} - 1))); do
        (has_ip6delegatedprefix ${i} && is_ip6addr_set ${i} \
            && ([ "${ip6_firewall[${i}]}" -eq 1 ] && is_ip6firewall_set ${i} || [ "${ip6_firewall[${i}]}" -eq 0 ]) \
            && is_dhcpd6_running ${i} || ! has_ip6delegatedprefix ${i}) \
            && is_ip4nataddr_set ${i} && is_dhcpd4_running ${i}

        if [ ! $? -eq 0 ]; then
            return 1
        fi
    done

    is_hostapd_running && is_forwarding_set && ([ -z "${new_gateway_interface}" ] || is_nat_set "${new_gateway_interface}")
}

## Setters

set_nat() {
    local gateway_interface=${1}

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

set_ipaddr() {
    local i=${1}
    local dev=$(devfromid "${i}")

    if ! is_ip4nataddr_set ${i}; then
        echo "hotspot${i}: Set IPv4 NAT address"
        ip address add "${ip4_nat_prefix[${i}]}.1/24" dev "${dev}"
    fi

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

set_ipfirewall() {
    local i=${1}
    local dev=$(devfromid "${i}")

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

    # Run DHCPv4 server
    if ! is_dhcpd4_running ${i}; then
        echo "hotspot${i}: Start the DHCPv4 server (dnsmasq)"

        cp /etc/dnsmasq.dhcpd/dhcpdv4{.conf.tpl,-ssid${i}.conf}

        sed "s|__WIFI_DEVICE__|${dev}|g" -i /etc/dnsmasq.dhcpd/dhcpdv4-ssid${i}.conf
        sed "s|__IP4_DNS__|${ip4_dns[${i}]}|g" -i /etc/dnsmasq.dhcpd/dhcpdv4-ssid${i}.conf
        sed "s|__IP4_NAT_PREFIX__|${ip4_nat_prefix[${i}]}|g" -i /etc/dnsmasq.dhcpd/dhcpdv4-ssid${i}.conf

        dnsmasq -C /etc/dnsmasq.dhcpd/dhcpdv4-ssid${i}.conf -p0 -x /run/dnsmasq/dnsmasq-dhcpv4-ssid${i}.pid
    fi

    # Run DHCPv6 server
    if has_ip6delegatedprefix ${i} && ! is_dhcpd6_running ${i}; then
        echo "hotspot${i}: Start the NDP and DHCPv6 server (dnsmasq)"

        cp /etc/dnsmasq.dhcpd/dhcpdv6{.conf.tpl,-ssid${i}.conf}

        sed "s|__WIFI_DEVICE__|${dev}|g" -i /etc/dnsmasq.dhcpd/dhcpdv6-ssid${i}.conf
        sed "s|__IP6_DNS__|${ip6_dns[${i}]}|g" -i /etc/dnsmasq.dhcpd/dhcpdv6-ssid${i}.conf
        sed "s|__IP6_NET__|${ip6_net[${i}]}|g" -i /etc/dnsmasq.dhcpd/dhcpdv6-ssid${i}.conf

        dnsmasq -C /etc/dnsmasq.dhcpd/dhcpdv6-ssid${i}.conf -p0 -x /run/dnsmasq/dnsmasq-dhcpv6-ssid${i}.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}"

    cp /etc/hostapd/hostapd.base.conf /etc/hostapd/hostapd.conf
    sed "s|__WIFI_DEVICE__|${wifi_device}|g" -i /etc/hostapd/hostapd.conf
    sed "s|__WIFI_CHANNEL__|${wifi_channel}|g" -i /etc/hostapd/hostapd.conf
    sed "s|__N_COMMENT__||g" -i /etc/hostapd/hostapd.conf

    for i in $(seq 0 $((${multissid} - 1))); do

        [ "${wifi_secure[${i}]}" -eq 1 ] && local sec_comment="" || local sec_comment="#"
        [ "${i}" -eq 0 ] && local bss_comment="#" || local bss_comment=""

        cp /etc/hostapd/hostapd.accesspoint.conf /etc/hostapd/hostapd.conf.tmp

        sed "s|__WIFI_INTERFACE__|hotspot${i}|g" -i /etc/hostapd/hostapd.conf.tmp
        sed "s|__WIFI_SSID__|${wifi_ssid[${i}]}|g" -i /etc/hostapd/hostapd.conf.tmp
        sed "s|__WIFI_PASSPHRASE__|${wifi_passphrase[${i}]}|g" -i /etc/hostapd/hostapd.conf.tmp
        sed "s|__SEC_COMMENT__|${sec_comment}|g" -i /etc/hostapd/hostapd.conf.tmp
        sed "s|__BSS_COMMENT__|${bss_comment}|g" -i /etc/hostapd/hostapd.conf.tmp

        cat /etc/hostapd/hostapd.conf.tmp >>/etc/hostapd/hostapd.conf
        rm /etc/hostapd/hostapd.conf.tmp
    done
}

## Unsetters

unset_nat() {
    local gateway_interface=${1}

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

unset_ipaddr() {
    local i=${1}
    local dev=$(devfromid "${i}")

    if is_ip4nataddr_set ${i}; then
        echo "hotspot${i}: Unset IPv4 NAT address"
        ip address delete "${ip4_nat_prefix[${i}]}.1/24" dev "${dev}"
    fi

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

unset_ipfirewall() {
    local i=${1}
    local dev=$(devfromid "${i}")

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

    if is_dhcpd6_running ${i}; then
        echo "hotspot${i}: Stop the NDP and DHCPv6 server (dnsmasq)"
        kill $(ps aux | grep 'dhcpdv6-ssid' | grep -v grep | awk '{ print $2 }')
        rm -f /etc/dnsmasq.dhcpd/dhcpdv6-ssid*.conf
    fi

    if is_dhcpd4_running ${i}; then
        echo "hotspot${i}: Stop the DHCPv4 server (dnsmasq)"
        kill $(ps aux | grep 'dhcpdv4-ssid' | grep -v grep | awk '{ print $2 }')
        rm -f /etc/dnsmasq.dhcpd/dhcpdv4-ssid*.conf
    fi
}

stop_dhcpd4() {
    :
}

stop_hostapd() {
    systemctl stop hostapd
}

## Tools

ynh_setting_get() {

    APP="$1" KEY="$2" python3 - <<EOF
import os, yaml, sys
app = os.environ['APP']
key = os.environ['KEY']
setting_file = "/etc/yunohost/apps/%s/settings.yml" % app
assert os.path.exists(setting_file), "Setting file %s does not exists ?" % setting_file
with open(setting_file) as f:
    settings = yaml.safe_load(f)
    if key in settings:
        print(settings[key])
EOF

}

ynh_setting_set() {

    # This is a partial copypasta of the official ynh_app_setting internal helper
    # In particular, we do this instead of relying on 'yunohost app setting' for
    # performance reasons (it takes a few second to run every yunohost commands)
    # and to remove the need for the infamous '--need-lock' option/issue.

    APP="$1" KEY="$2" VALUE="${3:-}" python3 - <<EOF
import os, yaml, sys
app = os.environ['APP']
key, value = os.environ['KEY'], os.environ.get('VALUE', None)
setting_file = "/etc/yunohost/apps/%s/settings.yml" % app
assert os.path.exists(setting_file), "Setting file %s does not exists ?" % setting_file
with open(setting_file) as f:
    settings = yaml.load(f)
settings[key] = value
with open(setting_file, "w") as f:
    yaml.safe_dump(settings, f, default_flow_style=False)
EOF

}

devfromid() {
    local i=${1}

    if [ "${i}" -eq 0 ]; then
        echo "${wifi_device}"
    else
        echo "hotspot${i}"
    fi
}

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

    # Variables

    echo -n "Retrieving Yunohost settings... "

    service_enabled=$(systemctl is-enabled ynh-hotspot)
    wifi_device=$(ynh_setting_get hotspot wifi_device)
    wifi_channel=$(ynh_setting_get hotspot wifi_channel)
    multissid=$(ynh_setting_get hotspot multissid)

    IFS='|' read -a wifi_ssid <<<"$(ynh_setting_get hotspot wifi_ssid)"
    IFS='|' read -a wifi_secure <<<"$(ynh_setting_get hotspot wifi_secure)"
    IFS='|' read -a wifi_passphrase <<<"$(ynh_setting_get hotspot wifi_passphrase)"
    IFS='|' read -a ip6_firewall <<<"$(ynh_setting_get hotspot ip6_firewall)"
    IFS='|' read -a ip6_net <<<"$(ynh_setting_get hotspot ip6_net)"
    IFS='|' read -a dns <<<"$(ynh_setting_get hotspot dns)"
    IFS='|' read -a ip4_nat_prefix <<<"$(ynh_setting_get hotspot ip4_nat_prefix)"
    for i in $(seq 0 $((${multissid} - 1))); do
        ip6_dns[${i}]=""
        ip4_dns[${i}]=""
        for ip in $(echo "${dns[${i}]}" | tr ',' ' '); do
            if [[ "$ip" == *":"* ]]; then
                ip6_dns[${i}]+="[$ip],"
            else
                ip4_dns[${i}]+="$ip,"
            fi
        done
        # Remove trailing ,
        ip6_dns[${i}]="${ip6_dns[${i}]%%,}"
        ip4_dns[${i}]="${ip4_dns[${i}]%%,}"
    done

    old_gateway_interface=$(ynh_setting_get hotspot gateway_interface)
    new_gateway_interface=$(ip route get 1.2.3.4 | awk '{ print $5; }')

    # Switch the NAT interface if there is a VPN
    ip link show dev tun0 &>/dev/null
    if [ "$?" -eq 0 ]; then
        new_gateway_interface=tun0
    fi

    echo "OK"
fi

# Script

case "$1" in
start)
    if is_running; then
        echo "Already started"
        exit 0
    elif [ "${service_enabled}" != "enabled" ]; then
        echo "Not starting because hotspod 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 "[hotspot] Starting..."
    touch /tmp/.ynh-hotspot-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; then
            journalctl -u hostapd -n 100 --no-hostname --no-pager
            exit 1
        fi

        sleep 1

        # On single SSID, the hotspot interface will be wlan0 (or similar)
        # in multissid, we additionally want to make sure that at least hotspot1 started
        if [ "${multissid}" -gt 1 ]; then
            i=0
            while ! ip link show dev "hotspot1" &>/dev/null; do
                sleep 1
                if [ ${i} -gt 20 ]; then
                    echo "Failed to see hotspot interface showing up in 'ip a'"
                    stop_hostapd
                    exit 1
                fi
                i=$(($i + 1))
            done
        fi
    fi

    # For each registred ssid
    for i in $(seq 0 $((${multissid} - 1))); do
        set_ipaddr ${i}
        set_ipfirewall ${i}
        start_dhcpd ${i}
    done

    # Update dynamic settings
    ynh_setting_set hotspot gateway_interface "${new_gateway_interface}"
    ;;
stop)
    echo "[hotspot] Stopping..."
    rm -f /tmp/.ynh-hotspot-started

    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

    for i in $(seq 0 $((${multissid} - 1))); do
        unset_ipaddr ${i}
        unset_ipfirewall ${i}
        stop_dhcpd ${i}
    done

    if is_hostapd_running; then
        echo "Stop hostapd"
        stop_hostapd
    fi

    # Fix configuration
    if has_vpnclient_app; then
        ynh-vpnclient start
    fi
    ;;
restart)
    $0 stop
    $0 start
    ;;
status)
    exitcode=0

    if [ "${service_enabled}" != "enabled" ]; 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

    for i in $(seq 0 $((${multissid} - 1))); do
        if has_ip6delegatedprefix ${i}; then
            echo "[INFO] hotspot${i}: IPv6 delegated prefix found"
            echo "[INFO] hotspot${i}: IPv6 address computed from the delegated prefix: $(ip6addrfromdelegatedprefix $i)"

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

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

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

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

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

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

exit 0