#!/bin/bash -x
((EUID == 0 )) || { echo "Need root"; exit 1; }

set -euo pipefail

confd=/etc/e-router
iptables=${IPTABLESCMD:-iptables}
source $confd/config

set_defaults() {
    /usr/lib/systemd/scripts/iptables-flush
    ${iptables} -P FORWARD DROP
    ${iptables} -P OUTPUT ACCEPT
    ${iptables} -P INPUT DROP
}

setup_final(){
    if $loginput ; then
        setup_wandroplog
        ${iptables} -A INPUT -j WAN-LOG-DROP
    else
        ${iptables} -A INPUT -j DROP
    fi
}

setup_wandroplog() {
    ${iptables} -N WAN-LOG-DROP
    if $debugtcp; then
        ${iptables} -A WAN-LOG-DROP -p tcp  -j LOG --log-prefix  "WAN-LOG-DROP TCP: " --log-level 7
        ${iptables} -A WAN-LOG-DROP -p tcp -j REJECT --reject-with tcp-reset
    fi
    if $debugudp; then
        ${iptables} -A WAN-LOG-DROP -p udp  -j LOG --log-prefix  "WAN-LOG-DROP UDP: " --log-level 7
        ${iptables} -A WAN-LOG-DROP -p udp -j REJECT --reject-with icmp-port-unreachable
    fi
    if $debugicmp; then
        ${iptables} -A WAN-LOG-DROP -p icmp -j LOG --log-prefix  "WAN-LOG-DROP ICMP: " --log-level 7
        ${iptables} -A WAN-LOG-DROP -j REJECT --reject-with icmp-proto-unreachable
    fi
}

setup_fordroplog() {
    ${iptables} -N FORWARD-LOG-DROP
    if $debugtcp; then
        ${iptables} -A FORWARD-LOG-DROP -p tcp  -j LOG --log-prefix "FORWARD-LOG-DROP TCP: " --log-level 7
        ${iptables} -A FORWARD-LOG-DROP -p tcp -j REJECT --reject-with tcp-reset
    fi
    if $debugudp; then
        ${iptables} -A FORWARD-LOG-DROP -p udp  -j LOG --log-prefix "FORWARD-LOG-DROP UDP: " --log-level 7
        ${iptables} -A FORWARD-LOG-DROP -p udp -j REJECT --reject-with icmp-port-unreachable
    fi
    if $debugicmp; then
        ${iptables} -A FORWARD-LOG-DROP -p icmp -j LOG --log-prefix "FORWARD-LOG-DROP ICMP: " --log-level 7
        ${iptables} -A FORWARD-LOG-DROP -j REJECT --reject-with icmp-proto-unreachable
    fi
}

setup_nat() {
    ${iptables} -t nat -A POSTROUTING -o ${wan} -s ${locnet} -j MASQUERADE
}

setup_forward() {
    ${iptables} -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    ${iptables} -A FORWARD -i ${eth0} -o ${wan} -j ACCEPT
    while read -r ip public private ; do
        [[ "$ip" =~ ^[0-9]{1,}.[0-9]{1,}.[0-9]{1,}.[0-9]{1,}$ ]] || continue
        [[ "$public" =~ ^[0-9]{1,}|[0-9]{1,}:[0-9]{1,}$ ]] || continue
        [[ "$private" =~ ^[0-9]{1,}|[0-9]{1,}:[0-9]{1,}$ ]] || continue
        if [[ "$public" =~ ^[0-9]{1,}$ ]] ; then
            ${iptables} -A PREROUTING -t nat -i ${wan} -p tcp --dport ${public} -j DNAT --to ${ip}:${private}
            ${iptables} -A FORWARD -i ${wan} -p tcp --syn -d ${ip} --dport ${private} -m conntrack --ctstate NEW --ctproto TCP -j ACCEPT
        else
            ${iptables} -A PREROUTING -t nat -i ${wan} -p tcp --dport ${public} -j DNAT --to ${ip}
            ${iptables} -A FORWARD -i ${wan} -p tcp --syn -d ${ip} --dport ${public} -m conntrack --ctstate NEW --ctproto TCP -j ACCEPT
        fi
    done < $confd/FORWARD.tcp

    while read -r ip public private ; do
        [[ "$ip" =~ ^[0-9]{1,}.[0-9]{1,}.[0-9]{1,}.[0-9]{1,}$ ]] || continue
        [[ "$public" =~ ^[0-9]{1,}|[0-9]{1,}:[0-9]{1,}$ ]] || continue
        [[ "$private" =~ ^[0-9]{1,}|[0-9]{1,}:[0-9]{1,}$ ]] || continue
        if [[ "$public" =~ ^[0-9]{1,}$ ]] ; then
            ${iptables} -A PREROUTING -t nat -i ${wan} -p udp --dport ${public} -j DNAT --to ${ip}:${private}
            ${iptables} -A FORWARD -i ${wan} -p udp -d ${ip} --dport ${private} -m conntrack --ctstate NEW --ctproto UDP -j ACCEPT
        else
            ${iptables} -A PREROUTING -t nat -i ${wan} -p udp --dport ${public} -j DNAT --to ${ip}
            ${iptables} -A FORWARD -i ${wan} -p udp -d ${ip} --dport ${public} -m conntrack --ctstate NEW --ctproto UDP -j ACCEPT
        fi
    done < $confd/FORWARD.udp

    if $logforward ; then
        setup_fordroplog
        ${iptables} -A FORWARD -j FORWARD-LOG-DROP
    else
        ${iptables} -A FORWARD -j DROP
    fi
}

setup_base() {
    ${iptables} -A INPUT -i lo -j ACCEPT
    ${iptables} -A INPUT -i ${eth0} -j ACCEPT
    ${iptables} -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    ${iptables} -A INPUT -m conntrack --ctstate INVALID -j DROP
}

setup_whitenets() {
    ipset create -! $whiteset hash:net hashsize 4096 timeout $whitettl maxelem $whitemaxelems
    while read -r net ; do
        [[ "$net" =~ ^[0-9]{1,}.[0-9]{1,}.[0-9]{1,}.[0-9]{1,}/[0-9]{1,}$ ]] || continue
        ipset -! add  $whiteset $net timeout 0
    done < $confd/WHITE.nets
}

setup_badips() {
    ipset create -! $banset hash:ip hashsize 4096 timeout $banttl  maxelem $badmaxelems
    ${iptables} -A INPUT -i ${wan} -p udp -m set --match-set $banset src -m conntrack --ctstate NEW --ctproto UDP -j REJECT --reject-with icmp-port-unreachable
    ${iptables} -A INPUT -i ${wan} -p tcp -m set --match-set $banset src -m conntrack --ctstate NEW --ctproto TCP -j REJECT --reject-with tcp-reset
}

setup_scanips() {
    ipset create -! $scanset hash:ip hashsize 4096 timeout $scanttl  maxelem $scanmaxelems
    ${iptables} -A INPUT -i ${wan} -p udp -m set --match-set $scanset src -m conntrack --ctstate NEW --ctproto UDP -j REJECT --reject-with icmp-port-unreachable
    ${iptables} -A INPUT -i ${wan} -p tcp -m set --match-set $scanset src -m conntrack --ctstate NEW --ctproto TCP -j REJECT --reject-with tcp-reset
}

setup_white() {
    ${iptables} -N FW-FILTERED
    while read -r port ; do
        [[ "$port" =~ ^[0-9]{1,}$ ]] || continue
        ${iptables} -A FW-FILTERED -p udp -m conntrack --ctstate NEW --ctproto UDP --dport $port -j ACCEPT
    done < $confd/WHITE.udp
    while read -r port ; do
        [[ "$port" =~ ^[0-9]{1,}$ ]] || continue
        ${iptables} -A FW-FILTERED -p tcp -m conntrack --ctstate NEW --ctproto TCP --dport $port -j ACCEPT
    done < $confd/WHITE.tcp
    ${iptables} -A INPUT -i ${wan} -p udp -m set --match-set $whiteset src -m conntrack --ctstate NEW --ctproto UDP -j FW-FILTERED
    ${iptables} -A INPUT -i ${wan} -p tcp -m set --match-set $whiteset src -m conntrack --ctstate NEW --ctproto TCP -j FW-FILTERED
    ${iptables} -A INPUT -i ${wan} -p icmp --icmp-type 8 -m set --match-set $whiteset src -m conntrack --ctstate NEW --ctproto ICMP -j ACCEPT
}

setup_public() {
    ${iptables} -N FW-PUBLIC
    while read -r port ; do
        [[ "$port" =~ ^[0-9]{1,}$ ]] || continue
        ${iptables} -A FW-PUBLIC -p udp -m conntrack --ctstate NEW --ctproto UDP --dport $port -j ACCEPT
    done < $confd/PUBLIC.udp
    while read -r port ; do
        [[ "$port" =~ ^[0-9]{1,}$ ]] || continue
        ${iptables} -A FW-PUBLIC -p tcp -m conntrack --ctstate NEW --ctproto TCP --dport $port -j ACCEPT
    done < $confd/PUBLIC.tcp
    ${iptables} -A INPUT -i ${wan} -p udp -m conntrack --ctstate NEW --ctproto UDP -j FW-PUBLIC
    ${iptables} -A INPUT -i ${wan} -p tcp -m conntrack --ctstate NEW --ctproto TCP -j FW-PUBLIC
}

setup_cast() {
    ${iptables} -N FW-CAST
    ${iptables} -A FW-CAST -m pkttype --pkt-type broadcast -j ACCEPT
    ${iptables} -A FW-CAST -m pkttype --pkt-type multicast -j ACCEPT
    ${iptables} -A INPUT -i ${wan} -j FW-CAST
}

main () {
    defaultHooks="set_defaults setup_whitenets setup_nat setup_forward setup_base setup_badips setup_white setup_public setup_scanips setup_cast setup_final"
    hookarray=(${hooks:-$defaultHooks})
    for hook in "${hookarray[@]}" ; do
        $hook
    done
}

main