. /lib/functions/network.sh

[ -n "$ZAPRET_BASE" ] || ZAPRET_BASE=/opt/zapret
. "$ZAPRET_BASE/config"

[ -n "$QNUM" ] || QNUM=200
[ -n "$TPPORT" ] || TPPORT=988
TPWS_USER=daemon
TPWS_LOCALHOST4=127.0.0.127
[ -n "$DESYNC_MARK" ] || DESYNC_MARK=0x40000000
[ -n "$OPENWRT_LAN" ] || OPENWRT_LAN=lan

# max wait time for the link local ipv6 on the LAN interface
LINKLOCAL_WAIT_SEC=5

IPSET_CR="$ZAPRET_BASE/ipset/create_ipset.sh"

CUSTOM_SCRIPT="$ZAPRET_BASE/init.d/openwrt/custom"
[ -f "$CUSTOM_SCRIPT" ] && . "$CUSTOM_SCRIPT"

IPSET_EXCLUDE="-m set ! --match-set nozapret"
IPSET_EXCLUDE6="-m set ! --match-set nozapret6"

NFQWS_OPT_DESYNC_HTTP="${NFQWS_OPT_DESYNC_HTTP:-$NFQWS_OPT_DESYNC}"
NFQWS_OPT_DESYNC_HTTPS="${NFQWS_OPT_DESYNC_HTTPS:-$NFQWS_OPT_DESYNC}"

exists()
{
 which "$1" >/dev/null 2>/dev/null
}
existf()
{
 type "$1" >/dev/null 2>/dev/null
}


# can be multiple ipv6 outgoing interfaces
# uplink from isp, tunnelbroker, vpn, ...
# want them all. who knows what's the real one that blocks sites
# dont want any manual configuration - want to do it automatically
# standard network_find_wan[6] return only the first
# we use low level function from network.sh to avoid this limitation
# it can change theoretically and stop working

network_find_wan_all()
{
 __network_ifstatus "$1" "" "[@.route[@.target='0.0.0.0' && !@.table]].interface" "" 10 2>/dev/null && return
 network_find_wan $1
}
network_find_wan6_all()
{
 __network_ifstatus "$1" "" "[@.route[@.target='::' && !@.table]].interface" "" 10 2>/dev/null && return
 network_find_wan6 $1
}

ipt()
{
	iptables -C "$@" >/dev/null 2>/dev/null || iptables -I "$@"
}
ipt_del()
{
	iptables -C "$@" >/dev/null 2>/dev/null && iptables -D "$@"
}
ipt6()
{
	ip6tables -C "$@" >/dev/null 2>/dev/null || ip6tables -I "$@"
}
ipt6_del()
{
	ip6tables -C "$@" >/dev/null 2>/dev/null && ip6tables -D "$@"
}

# there's no route_localnet for ipv6
# the best we can is to route to link local of the incoming interface
# OUTPUT - can DNAT to ::1
# PREROUTING - can't DNAT to ::1. can DNAT to link local of -i interface or to any global addr
# not a good idea to expose tpws to the world (bind to ::)

get_ipv6_linklocal()
{
 # $1 - interface name. if empty - any interface
 if exists ip ; then
    local dev
    [ -n "$1" ] && dev="dev $1"
    ip addr show $dev | sed -e 's/^.*inet6 \([^ ]*\)\/[0-9]* scope link.*$/\1/;t;d' | head -n 1
 else
    ifconfig $1 | sed -re 's/^.*inet6 addr: ([^ ]*)\/[0-9]* Scope:Link.*$/\1/;t;d' | head -n 1
 fi
}
get_ipv6_global()
{
 # $1 - interface name. if empty - any interface
 if exists ip ; then
    local dev
    [ -n "$1" ] && dev="dev $1"
    ip addr show $dev | sed -e 's/^.*inet6 \([^ ]*\)\/[0-9]* scope global.*$/\1/;t;d' | head -n 1
 else
    ifconfig $1 | sed -re 's/^.*inet6 addr: ([^ ]*)\/[0-9]* Scope:Global.*$/\1/;t;d' | head -n 1
 fi
}

dnat6_target()
{
 # $1 - lan network name
 # $2 - var to store target ip6
 # get target ip address for DNAT. prefer link locals
 # tpws should be as inaccessible from outside as possible
 # link local address can appear not immediately after ifup
 # DNAT6_TARGET=- means attempt was made but address was not found (to avoid multiple re-attempts)

 local DNAT6_TARGET DVAR=DNAT6_TARGET_$1
 DVAR=$(echo $DVAR | sed 's/[^a-zA-Z0-9_]/_/g')
 eval DNAT6_TARGET="\$$DVAR"
 [ -n "$2" ] && eval $2=''
 
 [ -n "$DNAT6_TARGET" ] || {
    # no reason to query if its down
    network_is_up $1 || return

    local DEVICE
    network_get_device DEVICE $1

    local ct=0
    while 
      DNAT6_TARGET=$(get_ipv6_linklocal $DEVICE)
      [ -n "$DNAT6_TARGET" ] && break
      [ "$ct" -ge "$LINKLOCAL_WAIT_SEC" ] && break
      echo $DEVICE: waiting for the link local for another $(($LINKLOCAL_WAIT_SEC - $ct)) seconds ...
      ct=$(($ct+1))
      sleep 1
    do :; done

    [ -n "$DNAT6_TARGET" ] || {
      echo $DEVICE: no link local. getting global
      DNAT6_TARGET=$(get_ipv6_global $DEVICE)
      [ -n "$DNAT6_TARGET" ] || {
        echo $DEVICE: could not get any address
        DNAT6_TARGET=-
      }
    }
    eval $DVAR="$DNAT6_TARGET"
 }
 [ -n "$2" ] && eval $2="$DNAT6_TARGET"
}


fw_nfqws_pre4()
{
 # $1 - filter ipv4
 # $2 - queue number

 local DEVICE wan_iface

 [ "$DISABLE_IPV4" = "1" ] || {
    network_find_wan_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt PREROUTING -t mangle -i $DEVICE -p tcp $1 $IPSET_EXCLUDE src -j NFQUEUE --queue-num $2 --queue-bypass
    done
 }
}
fw_nfqws_pre6()
{
 # $1 - filter ipv6
 # $2 - queue number

 local DEVICE wan_iface

 [ "$DISABLE_IPV6" = "1" ] || {
    network_find_wan6_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt6 PREROUTING -t mangle -i $DEVICE -p tcp $1 $IPSET_EXCLUDE6 src -j NFQUEUE --queue-num $2 --queue-bypass
    done
 }
}
fw_nfqws_pre()
{
 # $1 - filter ipv4
 # $2 - filter ipv6
 # $3 - queue number

 fw_nfqws_pre4 "$1" $3
 fw_nfqws_pre6 "$2" $3
}
fw_nfqws_post4()
{
 # $1 - filter ipv4
 # $2 - queue number

 local DEVICE wan_iface

 [ "$DISABLE_IPV4" = "1" ] || {
    network_find_wan_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt POSTROUTING -t mangle -o $DEVICE -p tcp $1 $IPSET_EXCLUDE dst -j NFQUEUE --queue-num $2 --queue-bypass
    done
 }
}
fw_nfqws_post6()
{
 # $1 - filter ipv6
 # $2 - queue number

 local DEVICE wan_iface

 [ "$DISABLE_IPV6" = "1" ] || {
    network_find_wan6_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt6 POSTROUTING -t mangle -o $DEVICE -p tcp $1 $IPSET_EXCLUDE6 dst -j NFQUEUE --queue-num $2 --queue-bypass
    done
 }
}
fw_nfqws_post()
{
 # $1 - filter ipv4
 # $2 - filter ipv6
 # $3 - queue number

 fw_nfqws_post4 "$1" $3
 fw_nfqws_post6 "$2" $3
}


IPT_OWNER="-m owner ! --uid-owner $TPWS_USER"
fw_tpws4()
{
 # $1 - filter ipv6
 # $2 - tpws port

 local DEVICE wan_iface
 
 [ "$DISABLE_IPV4" = "1" ] || {
    network_find_wan_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt OUTPUT -t nat -o $DEVICE $IPT_OWNER -p tcp $1 $IPSET_EXCLUDE dst -j DNAT --to $TPWS_LOCALHOST4:$2
    done
    
    # allow localnet route only to special tpws IP
    iptables -N input_rule_zapret 2>/dev/null
    ipt input_rule_zapret -d 127.0.0.0/8 -j DROP
    ipt input_rule_zapret -d $TPWS_LOCALHOST4 -j RETURN

    for lan in $OPENWRT_LAN; do
	network_get_device DEVICE $lan
	[ -n "$DEVICE" ] || continue
	ipt prerouting_rule -t nat -i $DEVICE -p tcp $1 $IPSET_EXCLUDE dst -j DNAT --to $TPWS_LOCALHOST4:$2
	ipt input_rule -i $DEVICE -j input_rule_zapret
	sysctl -qw net.ipv4.conf.$DEVICE.route_localnet=1
    done
 }
}
fw_tpws6()
{
 # $1 - filter ipv6
 # $2 - tpws port

 local DEVICE wan_iface DNAT6
 
 [ "$DISABLE_IPV6" = "1" ] || {
    network_find_wan6_all wan_iface
    for ext_iface in $wan_iface; do
       network_get_device DEVICE $ext_iface
       ipt6 OUTPUT -t nat -o $DEVICE $IPT_OWNER -p tcp $1 $IPSET_EXCLUDE6 dst -j DNAT --to [::1]:$2
    done
    for lan in $OPENWRT_LAN; do
	network_get_device DEVICE $lan
	[ -n "$DEVICE" ] || continue
	dnat6_target $lan DNAT6
	[ "$DNAT6" != '-' ] && ipt6 PREROUTING -t nat -i $DEVICE -p tcp $1 $IPSET_EXCLUDE6 dst -j DNAT --to [$DNAT6]:$2
    done
 }
}
fw_tpws()
{
 # $1 - filter ipv4
 # $2 - filter ipv6
 # $3 - tpws port

 fw_tpws4 "$1" $3
 fw_tpws6 "$2" $3
}

filter_apply_port_target()
{
	# $1 - var name of iptables filter
	local f
	if [ "$MODE_HTTP" = "1" ] && [ "$MODE_HTTPS" = "1" ]; then
		f="-m multiport --dports 80,443"
	elif [ "$MODE_HTTPS" = "1" ]; then
		f="--dport 443"
	elif [ "$MODE_HTTP" = "1" ]; then
		f="--dport 80"
	else
		echo WARNING !!! HTTP and HTTPS are both disabled
	fi
	eval $1="\"\$$1 $f\""
}
filter_apply_ipset_target()
{
	# $1 - var name of ipv4 iptables filter
	# $2 - var name of ipv6 iptables filter
	if [ "$MODE_FILTER" = "ipset" ]; then
		eval $1="\"\$$1 -m set --match-set zapret dst\""
		eval $2="\"\$$2 -m set --match-set zapret6 dst\""
	fi
}


create_ipset()
{
 echo "Creating ipset"
 "$IPSET_CR" "$@"
}


is_flow_offload_avail()
{
	# $1 = '' for ipv4, '6' for ipv6
	grep -q FLOWOFFLOAD /proc/net/ip$1_tables_targets
}
list_nfqws_rules()
{
	# $1 = '' for ipv4, '6' for ipv6
	ip$1tables -S POSTROUTING -t mangle  | grep -E "NFQUEUE --queue-num $QNUM --queue-bypass|NFQUEUE --queue-num $(($QNUM+1)) --queue-bypass"  | \
	sed -re 's/^-A POSTROUTING (.*) -j NFQUEUE.*$/\1/' -e "s/-m mark ! --mark $DESYNC_MARK\/$DESYNC_MARK//"
}
reverse_nfqws_rule()
{
	sed -e 's/-o /-i /' -e 's/--dport /--sport /' -e 's/--dports /--sports /' -e 's/ dst$/ src/' -e 's/ dst / src /'
}
apply_flow_offloading_enable_rule()
{
	# $1 = '' for ipv4, '6' for ipv6
	local i off='-j FLOWOFFLOAD'
	[ "$FLOWOFFLOAD" = "hardware" ] && off="$off --hw"
	i="forwarding_rule_zapret -m comment --comment zapret_traffic_offloading_enable -m conntrack --ctstate RELATED,ESTABLISHED $off"
	echo enabling ipv${1:-4} flow offloading : $i
	ip$1tables -A $i
}
apply_flow_offloading_exempt_rule()
{
	# $1 = '' for ipv4, '6' for ipv6
	local i v
	v=$1
	shift
	i="forwarding_rule_zapret $@ -m comment --comment zapret_traffic_offloading_exemption -j RETURN"
	echo applying ipv${v:-4} flow offloading exemption : $i
	ip${v}tables -A $i
}
flow_offloading_exempt_v()
{
	# $1 = '' for ipv4, '6' for ipv6

	is_flow_offload_avail $1 || return 0

	ipt$1_del forwarding_rule -j forwarding_rule_zapret
	ip$1tables -F forwarding_rule_zapret 2>/dev/null
	ip$1tables -X forwarding_rule_zapret 2>/dev/null

	[ "$FLOWOFFLOAD" = 'software' -o "$FLOWOFFLOAD" = 'hardware' ] && {
		ip$1tables -N forwarding_rule_zapret

		list_nfqws_rules $1 |
		while read rule; do
			apply_flow_offloading_exempt_rule "$1" $rule
		done

		list_nfqws_rules $1 | grep -v "connbytes" | reverse_nfqws_rule |
		while read rule; do
			apply_flow_offloading_exempt_rule "$1" $rule
		done
	
		apply_flow_offloading_enable_rule $1

		ipt$1 forwarding_rule -j forwarding_rule_zapret
	}

	return 0
}
flow_offloading_exempt()
{
	[ "$DISABLE_IPV4" = "1" ] || flow_offloading_exempt_v
	[ "$DISABLE_IPV6" = "1" ] || flow_offloading_exempt_v 6
}


zapret_apply_firewall()
{
	local first_packet_only="-m connbytes --connbytes-dir=original --connbytes-mode=packets --connbytes 1:4"
	local desync="-m mark ! --mark $DESYNC_MARK/$DESYNC_MARK"
	local f4 f6
	local qn

	# always create ipsets. ip_exclude ipset is required
	create_ipset no-update

	case "${MODE}" in
		tpws)
			if [ ! "$MODE_HTTP" = "1" ] && [ ! "$MODE_HTTPS" = "1" ]; then
				echo both http and https are disabled. not applying redirection.
			else
				filter_apply_port_target f4
				f6=$f4
				filter_apply_ipset_target f4 f6
				fw_tpws "$f4" "$f6" $TPPORT
			fi
			;;
	
		nfqws)
			if [ ! "$MODE_HTTP" = "1" ] && [ ! "$MODE_HTTPS" = "1" ]; then
				echo both http and https are disabled. not applying redirection.
			else
				if [ "$MODE_HTTP_KEEPALIVE" != "1" ] && [ "$NFQWS_OPT_DESYNC_HTTP" = "$NFQWS_OPT_DESYNC_HTTPS" ]; then
					filter_apply_port_target f4
					f4="$f4 $first_packet_only"
					f6=$f4
					filter_apply_ipset_target f4 f6
					fw_nfqws_post "$f4 $desync" "$f6 $desync" $QNUM
				else
					if [ "$MODE_HTTP" = "1" ]; then
						f4="--dport 80"
						[ "$MODE_HTTP_KEEPALIVE" = "1" ] || f4="$f4 $first_packet_only"
						f6=$f4
						filter_apply_ipset_target f4 f6
						fw_nfqws_post "$f4 $desync" "$f6 $desync" $QNUM
					fi
					if [ "$MODE_HTTPS" = "1" ]; then
						f4="--dport 443 $first_packet_only"
						f6=$f4
						filter_apply_ipset_target f4 f6
						qn=$QNUM
						[ "$NFQWS_OPT_DESYNC_HTTP" = "$NFQWS_OPT_DESYNC_HTTPS" ] || qn=$(($QNUM+1))
						fw_nfqws_post "$f4 $desync" "$f6 $desync" $qn
					fi
				fi
			fi
			;;
		custom)
	    		existf zapret_custom_firewall && zapret_custom_firewall
			;;
	esac

	flow_offloading_exempt
}