#!/bin/sh
# Copyright (c) 2012 OpenWrt.org
. /lib/functions.sh
. /lib/functions/service.sh
. /lib/functions/network.sh

config_load network6
local NAT="ip6tables -t nat"

conf_get() {
	local __return="$1"
	local __device="$2"
	local __option="$3"
	local __value=$(cat "/proc/sys/net/ipv6/conf/$device/$option")
	eval "$__return=$__value"
}


conf_set() {
	local device="$1"
	local option="$2"
	local value="$3"
	echo "$value" > "/proc/sys/net/ipv6/conf/$device/$option"
}


stop_service() {
	local __exe="$1"
	SERVICE_PID_FILE="$2"
	local __return="$3"

	service_check "$__exe" && {
		service_stop "$__exe"
		[ -n "$__return" ] && eval "$__return=1"
	}
	rm -f "$SERVICE_PID_FILE"
}


start_service() {
	local cmd="$1"
	local pidfile="$2"

	SERVICE_DAEMONIZE=1
	SERVICE_WRITE_PID=1
	SERVICE_PID_FILE="$pidfile"
	service_start $cmd
}


resolve_network_add() {
	local __section="$1"
	local __device="$2"
	local __return="$3"
	local __cdevice
	network_get_device __cdevice "$__section"
	[ "$__cdevice" != "$__device" ] && return
	
	eval "$__return"'="'"$__section"'"'
}


resolve_network() {
	local __return="$1"
	local __device="$2"
	config_foreach resolve_network_add interface "$__device" "$__return"
}


setup_masquerading() {
	local cmd="$1"
	local chain="network6_masquerade_$2"
	local device="$3"

	$NAT -D POSTROUTING -j "$chain" 2>/dev/null && {
		$NAT -F "$chain" 2>/dev/null
		$NAT -X "$chain" 2>/dev/null
	}

	[ "$cmd" != "stop" ] && {
		$NAT -N "$chain"
		$NAT -A "$chain" -o "$device" -j MASQUERADE
		$NAT -A POSTROUTING -j "$chain"
	}
}


setup_npt_chain() {
	local cmd="$1"
	local network="$2"
	local chain="network6_npt_$network"

	[ "$cmd" != "start" ] && {
		$NAT -D POSTROUTING -j "$chain" 2>/dev/null && {
			$NAT -D PREROUTING -j "$chain" 2>/dev/null
			$NAT -F "$chain" 2>/dev/null
			$NAT -X "$chain" 2>/dev/null
		}
	}

	[ "$cmd" != "stop" ] && {
		$NAT -N "$chain" 2>/dev/null && {
			$NAT -A PREROUTING -j "$chain"
			$NAT -A POSTROUTING -j "$chain"
		}
	}
}


announce_prefix() {
	local prefix="$1"
	local network="$2"
	local cmd="$3"
	local type="$4"

	local addr=$(echo "$prefix" | cut -d/ -f1)
	local rem=$(echo "$prefix" | cut -d/ -f2)
	local length=$(echo "$rem" | cut -d, -f1)
	local prefer=""
	local valid=""

	# If preferred / valid provided
	[ "$rem" != "$length" ] && {
		prefer=$(echo "$rem" | cut -d, -f2)
		valid=$(echo "$rem" | cut -d, -f3)
	}

	# Get prefix configuration
	local ula=""
	local prefix_action=""
	config_get ula global ula_prefix
	config_get prefix_action "$network" prefix_action
	[ -z "$prefix_action" ] && prefix_action="distribute"

	# Always announce the ULA when doing NPT
	[ "$prefix" == "$ula" -a "$prefix_action" == "npt" ] && prefix_action="distribute"

	[ "$prefix_action" == "distribute" -o "$prefix_action" == "npt" ] && {
		local msg='{"network": "'"$network"'", "prefix": "'"$addr"'", "length": '"$length"
		[ -n "$valid" ] && msg="$msg"', "valid": '"$valid"', "preferred": '"$prefer"
		[ -z "$cmd" ] && cmd=newprefix

		[ "$prefix_action" == "npt" ] && msg="$msg"', "npt": 1'
		[ "$type" == "secondary" ] && msg="$msg"', "secondary": 1'
		ubus call 6distributed "$cmd" "$msg}"
	}

	[ "$prefix_action" == "npt" ] && {
		local chain="network6_npt_$network"
		local ula_addr=$(echo "$ula" | cut -d/ -f1)
		local ula_rem=$(echo "$ula" | cut -d/ -f2)
		local ula_length=$(echo "$ula_rem" | cut -d, -f1)
		local device=""

		network_get_device device "$network"
		[ "$length" -lt "$ula_length" ] && length="$ula_length"
		[ "$cmd" == "delprefix" ] && cmd="-D $chain" || cmd="-A $chain"

		local in="-i $device -d $addr/$length -j NETMAP --to $ula_addr/$ula_length"
		local out="-o $device -s $ula_addr/$ula_length -j NETMAP --to $addr/$length"

		setup_npt_chain start "$network"
		$NAT $cmd $in
		$NAT $cmd $out
	}
}


disable_router() {
	local network="$1"

	# Notify the address distribution daemon
	ubus call 6distributed deliface '{"network": "'"$network"'"}'

	# Disable advertisement daemon
	stop_service /usr/sbin/6relayd "/var/run/ipv6-router-$network.pid"
}


restart_relay_slave() {
	local __section="$1"
	local __master="$2"

	network_is_up "$__section" || return

	local __device=""
	network_get_device __device "$__section"

	local __cmaster=""
	config_get __cmaster "$__section" relay_master

	[ "$__master" == "$__cmaster" ] && {
		disable_interface "$__section"
		enable_interface "$__section" "$__device"
	}
}


add_relay_slave() {
	local __section="$1"
	local __return="$2"
	local __master="$3"
	local __mode="$4"

	network_is_up "$__section" || return

	# Get device
	local __device=""
	network_get_device __device "$__section"

	# Match master network
	local __cmaster=""
	config_get __cmaster "$__section" relay_master
	[ "$__master" == "$__cmaster" ] || return
	
	# Test slave  mode
	local __cmode=""
	config_get __cmode "$__section" mode
	[ "$__cmode" == "downstream" ] && __cmode="router"

	# Don't start fallback interfaces if we are in forced-relay mode
	[ "$__cmode" == "relay" -o "$__mode" == "fallback" ] || return

	# Don't make non-relay or non-router interfaces slaves
	[ "$__cmode" == "relay" -o "$__cmode" == "router" ] || return

	# Disable any active distribution
	[ "$__cmode" == "router" ] && disable_router "$__section"

	# Configure interface to accept RA and send RS
	conf_set "$__device" accept_ra 2
	conf_set "$__device" forwarding 2

	eval "$__return"'="$'"$__return"' '"$__device"'"'
}


stop_relay() {
	local network="$1"
	local pid_fallback="/var/run/ipv6-relay-fallback-$network.pid"
	local pid_forced="/var/run/ipv6-relay-forced-$network.pid"
	local was_fallback=""
	
	stop_service /usr/sbin/6relayd "$pid_fallback" was_fallback
	stop_service /usr/sbin/6relayd "$pid_forced"

	# Reenable normal distribution on slave interfaces	
	[ -n "$was_fallback" ] && config_foreach restart_relay_slave interface "$network"
}


detect_forced_relay_mode() {
	local __section="$1"
	local __mode="$2"

	local __cmode
	config_get __cmode "$__section" mode
	[ "$__cmode" == "relay" ] && eval "$__mode=forced"
}


restart_relay() {
	local network="$1"
	local mode="$2"

	# Stop last active relay
	stop_relay "$network"

	# Detect if we have a forced-relay
	[ -z "$mode" ] && config_foreach detect_forced_relay_mode interface mode

	# Don't start without a mode
	[ -z "$mode" ] && return

	# Detect master device
	local device=""
	network_get_device device "$network"

	# Generate command string
	local cmd="/usr/sbin/6relayd -A $device"
	local ifaces=""
	config_foreach add_relay_slave interface ifaces "$network" "$mode"

	# Start relay
	local pid="/var/run/ipv6-relay-$mode-$network.pid"
	[ -n "$ifaces" ] && start_service "$cmd $ifaces" "$pid"

	# There are no slave interface, however indicate that we want to relay
	[ -z "$ifaces" ] && touch "$pid"
}


setup_prefix_fallback() {
	local cmd="$1"
	local network="$2"
	local device="$3"

	stop_relay "$network"
	restart_relay "$network"

	setup_masquerading stop "$network"

	[ "$cmd" != "stop" ] && {
		local fallback=""
		config_get fallback "$network" prefix_fallback

		[ "$fallback" == "relay" ] && restart_relay "$network" fallback
		[ "$fallback" == "masquerade" ] && setup_masquerading start "$network" "$device"
	}
}


restart_master_relay() {
	local network="$1"
	local mode="$2"
	local pid_fallback="/var/run/ipv6-relay-fallback-$network.pid"
	local pid_forced="/var/run/ipv6-relay-forced-$network.pid"

	# Disable active relaying to this interface
	config_get relay_master "$network" relay_master
	[ -z "$relay_master" ] && return
	network_is_up "$relay_master" || return

	# Detect running mode
	[ -z "$mode" && -f "$pid_fallback" ] && mode="fallback"
	[ -z "$mode" && -f "$pid_forced" ] && mode="forced"

	# Restart relay if running or start requested
	[ -n "$mode" ] && restart_relay "$relay_master" "$mode"
}


disable_interface() {
	local network="$1"

	# Delete all prefixes routed to this interface
	ubus call 6distributed delprefix '{"network": "'"$network"'"}'

	# Restart Relay
	restart_master_relay "$network"

	# Disable distribution
	disable_router "$network"

	# Disable any active relays, masquerading rules and NPT rules
	stop_relay "$network"
	setup_masquerading stop "$network"
	setup_npt_chain stop "$network"

	# Disable DHCPv6 client if enabled, state script will take care
	stop_service /usr/sbin/odhcp6c "/var/run/ipv6-dhcpv6-$network.pid"
}


enable_ula_prefix() {
	local network="$1"
	local ula="$2"
	[ -z "$ula" ] && ula="global"

	# ULA-integration
	local ula_prefix=""
	config_get ula_prefix "$ula" ula_prefix

	# ULA auto configuration (first init)
	[ "$ula_prefix" == "auto" ] && {
		local r1=""
		local r2=""
		local r3=""

		# Sometimes results are empty, therefore try until it works...		
		while [ -z "$r1" -o -z "$r2" -o -z "$r3" ]; do
			r1=$(printf "%02x" $(($(</dev/urandom tr -dc 0-9 | dd bs=9 count=1) % 256)))
			r2=$(printf "%01x" $(($(</dev/urandom tr -dc 0-9 | dd bs=9 count=1) % 65536)))
			r3=$(printf "%01x" $(($(</dev/urandom tr -dc 0-9 | dd bs=9 count=1) % 65536)))
		done
		
		ula_prefix="fd$r1:$r2:$r3::/48"

		# Save prefix so it will be preserved across reboots
		config_set "$ula" ula_prefix "$ula_prefix"
		uci_set network6 "$ula" ula_prefix "$ula_prefix"
		uci_commit network6
	}

	# Announce ULA
	[ -n "$ula_prefix" ] && announce_prefix "$ula_prefix" "$network" newprefix secondary
}


enable_static() {
	local network="$1"
	local device="$2"

	# Enable global forwarding
	local global_forward
	conf_get global_forward all forwarding
	[ "$global_forward" != "1" ] && conf_set all forwarding 1

	# Configure device
	conf_set "$device" accept_ra 1
	conf_set "$device" forwarding 1

	# Enable ULA
	enable_ula_prefix "$network"
	# Compatibility (deprecated)
	enable_ula_prefix "$network" "$network"

	# Announce all static prefixes
	config_list_foreach "$network" static_prefix announce_prefix $network

	# start relay if there are forced relay members
	restart_relay "$network"
}


enable_router() {
	local network="$1"
	local device="$2"

	# Get IPv6 prefixes
	local length
	config_get length "$network" advertise_prefix
	[ -z "$length" ] && length=64
	[ "$length" -ne "0" ] && ubus call 6distributed newiface '{"network": "'"$network"'", "iface": "'"$device"'", "length": '"$length"'}'

	# Start RD & DHCPv6 service
	local pid="/var/run/ipv6-router-$network.pid"
	start_service "/usr/sbin/6relayd -S . $device" "$pid"

	# Try relaying if necessary
	restart_master_relay "$network"
}


enable_dhcpv6() {
	local network="$1"
	local device="$2"
	
	# Configure device
	conf_set "$device" accept_ra 2
	conf_set "$device" forwarding 2
	
	# Trigger RS
	conf_set "$device" disable_ipv6 1
	conf_set "$device" disable_ipv6 0

	# Configure DHCPv6-client
	local dhcp6_opts="$device"

	# Configure DHCPv6-client (e.g. requested prefix)
	local request_prefix
	config_get request_prefix "$network" request_prefix
	[ -z "$request_prefix" ] && request_prefix="auto"
	[ "$request_prefix" != "no" ] && {
		[ "$request_prefix" == "auto" ] && request_prefix=0
		dhcp6_opts="-P$request_prefix $dhcp6_opts"
	}
	
	# Start DHCPv6 client
	local pid="/var/run/ipv6-dhcpv6-$network.pid"
	start_service "/usr/sbin/odhcp6c -s/lib/ipv6/dhcpv6.sh $dhcp6_opts" "$pid"

	# Refresh RA on all interfaces
	for pid in /var/run/ipv6-router-*.pid; do
		kill -SIGUSR1 $(cat "$pid")
	done
}


enable_6to4() {
	local network="$1"
	local device="$2"
	local mode="$3"

	local prefixlen="48"
	[ "$mode" == "6rd" ] && {
		local ip4prefix=$(uci_get network "$network" ip4prefixlen 0)
		local ip6prefix=$(uci_get network "$network" ip6prefixlen 32)
		prefixlen=$(($ip6prefix + 32 - $ip4prefix))
	}

	local prefix=""
	network_get_ipaddr6 prefix "$network"

	announce_prefix "$prefix/$prefixlen" "$network"
}


enable_interface()
{
	local network="$1"
	local device="$2"
	local mode=""

	config_get mode "$network" mode
	[ -n "$mode" -a "$mode" != "none" ] || return

	# Compatibility with old mode names
	[ "$mode" == "downstream" ] && mode=router
	[ "$mode" == "upstream" ] && mode=dhcpv6

	# Run mode startup code
	enable_static "$network" "$device"
	[ "$mode" == "dhcpv6" ] && enable_dhcpv6 "$network" "$device"
	[ "$mode" == "router" ] && enable_router "$network" "$device"
	[ "$mode" == "6to4" -o "$mode" == "6rd" ] && enable_6to4 "$network" "$device" "$mode"
	[ "$mode" == "relay" ] && restart_master_relay "$network" forced
}
