--[[
LuCI - Lua Configuration Interface

Copyright 2008 Steven Barth <steven@midlink.org>
Copyright 2008 Jo-Philipp Wich <xm@leipzig.freifunk.net>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

$Id$

]]--

local uci = require "luci.model.uci".cursor()
local tools = require "luci.tools.ffwizard"
local util = require "luci.util"

local io = require "io"


-------------------- View --------------------
f = SimpleForm("siitwizward", "4over6-Assistent",
 "Dieser Assistent unterstüzt bei der Einrichtung von IPv4-over-IPv6 Translation.")

mode = f:field(ListValue, "mode", "Betriebsmodus")
mode:value("gateway", "Gateway")
mode:value("client", "Client")

dev = f:field(ListValue, "device", "WLAN-Gerät")
uci:foreach("network", "interface",
	function(section)
		if section[".name"] ~= "siit0" then
			dev:value(section[".name"])
		end
	end)


-------------------- Control --------------------
LL_PREFIX = luci.ip.IPv6("fe80::/16")

--
-- find link-local address
--
function find_ll(dev)
	for _, r in ipairs(luci.sys.net.routes6()) do
		if r.device == dev and LL_PREFIX:contains(r.dest) then
			return r.dest:sub(LL_PREFIX)
		end
	end
	return luci.ip.IPv6("::")
end



function f.handle(self, state, data)
	if state == FORM_VALID then
		luci.http.redirect(luci.dispatcher.build_url("admin", "uci", "changes"))
		return false
	elseif state == FORM_INVALID then
		self.errmessage = "Ungültige Eingabe: Bitte die Formularfelder auf Fehler prüfen."
	end
	return true
end

function mode.write(self, section, value)

	--
	-- Determine defaults
	--
	local ula_prefix  = uci:get("siit", "defaults", "ula_prefix")  or "fd00::"
	local ula_global  = uci:get("siit", "defaults", "ula_global")  or "00ca:ffee:babe::"		-- = Freifunk
	local ula_subnet  = uci:get("siit", "defaults", "ula_subnet")  or "0000:0000:0000:4223::"	-- = Berlin
	local siit_prefix = uci:get("siit", "defaults", "siit_prefix") or "::ffff:ffff:0000:0000"
	local siit_route  = luci.ip.IPv6(siit_prefix .. "/96")

	-- Find wifi interface
	local device = dev:formvalue(section)

	--
	-- Generate ULA
	--
	local ula = luci.ip.IPv6("::")

	for _, prefix in ipairs({ ula_prefix, ula_global, ula_subnet }) do
		ula = ula:add(luci.ip.IPv6(prefix))
	end

	ula = ula:add(find_ll(uci:get("network", device, "ifname") or device))


	--
	-- Gateway mode
	--
	--	* wan port is dhcp, lan port is 172.23.1.1/24
	--	* siit0 gets a dummy address: 169.254.42.42
	--	* wl0 gets an ipv6 address, in this case the fdca:ffee:babe::1:1/64
	--	* we do a ::ffff:ffff:0/96 route into siit0, so everything from 6mesh goes into translation.
	--	* an HNA6 of ::ffff:ffff:0:0/96 announces the mapped 0.0.0.0/0 ipv4 space.
	--	* MTU on WAN, LAN down to 1400, ipv6 headers are slighly larger.

	if value == "gateway" then

		uci:set("network", "wan", "mtu", 1400)


	--
	-- Client mode
	--
	--	* 172.23.2.1/24 on its lan, fdca:ffee:babe::1:2 on wl0 and the usual dummy address on siit0.
	--	* we do a ::ffff:ffff:172.13.2.0/120 to siit0, because in this case, only traffic directed to clients needs to go into translation.
	--	* same route as HNA6 announcement to catch the traffic out of the mesh.
	--	* Also, MTU on LAN reduced to 1400.

	else
		local lan_ip = luci.ip.IPv4(
			uci:get("network", "lan", "ipaddr"),
			uci:get("network", "lan", "netmask")
		)

		siit_route = luci.ip.IPv6(
			siit_prefix .. "/" .. (96 + lan_ip:prefix())
		):add(lan_ip[2])

	end

	-- siit0 interface
	uci:delete_all("network", "interface",
		function(s) return ( s.ifname == "siit0" ) end)

	uci:section("network", "interface", "siit0", {
		ifname  = "siit0",
		proto   = "static",
		ipaddr  = "169.254.42.42",
		netmask = "255.255.255.0"
	})

	-- siit0 route
	uci:delete_all("network", "route6",
		function(s) return siit_route:contains(luci.ip.IPv6(s.target)) end)

	uci:section("network", "route6", nil, {
		interface = device,
		target    = siit_route:string()
	})

	-- interface
	uci:set("network", device, "ip6addr", ula:string())
	uci:set("network", "lan", "mtu", 1400)

	uci:set("olsrd", "general", "IpVersion", 6)
	uci:foreach("olsrd", "Interface",
		function(s)
			if s.interface == device then
				uci:set("olsrd", s[".name"], "Ip6AddrType", "global")
			end
			uci:delete("olsrd", s[".name"], "Ip4Broadcast")
		end)

	-- hna6
	uci:delete_all("olsrd", "Hna6",
		function(s)
			if s.netaddr and s.prefix then
				return siit_route:contains(luci.ip.IPv6(s.netaddr.."/"..s.prefix))
			end
		end)

	uci:section("olsrd", "Hna6", nil, {
		netaddr = siit_route:host():string(),
		prefix  = siit_route:prefix()
	})

	uci:save("network")
	uci:save("olsrd")
end

return f