#!/usr/bin/lua

require("luci.util")
require("luci.model.uci")
require("luci.sys")
require("luci.sys.iptparser")

-- Init state session
local uci = luci.model.uci.cursor_state()
local ipt = luci.sys.iptparser.IptParser()
local net = luci.sys.net

local limit_up = 0
local limit_down = 0

function lock()
	os.execute("lock -w /var/run/luci_splash.lock && lock /var/run/luci_splash.lock")
end

function unlock()
	os.execute("lock -u /var/run/luci_splash.lock")
end

function main(argv)
	local cmd = table.remove(argv, 1)
	local arg = argv[1]

	limit_up = tonumber(uci:get("luci_splash", "general", "limit_up")) or 0
	limit_down = tonumber(uci:get("luci_splash", "general", "limit_down")) or 0

	if ( cmd == "lease" or cmd == "add-rules" or cmd == "remove" or
	     cmd == "whitelist" or cmd == "blacklist" or cmd == "status" ) and #argv > 0
	then
		lock()

		local arp_cache      = net.arptable()
		local leased_macs    = get_known_macs("lease")
		local blacklist_macs = get_known_macs("blacklist")
		local whitelist_macs = get_known_macs("whitelist")

		for i, adr in ipairs(argv) do
			local mac = nil
			if adr:find(":") then
				mac = adr:lower()
			else
				for _, e in ipairs(arp_cache) do
					if e["IP address"] == adr then
						mac = e["HW address"]:lower()
						break
					end
				end
			end

			if mac and cmd == "add-rules" then
				if leased_macs[mac] then
					add_lease(mac, arp_cache, true)
				elseif blacklist_macs[mac] then
					add_blacklist_rule(mac)
				elseif whitelist_macs[mac] then
					add_whitelist_rule(mac)
				end
			elseif mac and cmd == "status" then
				print(leased_macs[mac] and "lease"
					or whitelist_macs[mac] and "whitelist"
					or blacklist_macs[mac] and "blacklist"
					or "new")
			elseif mac and ( cmd == "whitelist" or cmd == "blacklist" or cmd == "lease" ) then
				if cmd ~= "lease" and leased_macs[mac] then
					print("Removing %s from leases" % mac)
					remove_lease(mac)
					leased_macs[mac] = nil
				end

				if cmd ~= "whitelist" and whitelist_macs[mac] then
					print("Removing %s from whitelist" % mac)
					remove_whitelist(mac)
					whitelist_macs[mac] = nil					
				end

				if cmd ~= "blacklist" and blacklist_macs[mac] then
					print("Removing %s from blacklist" % mac)
					remove_blacklist(mac)
					blacklist_macs[mac] = nil
				end

				if cmd == "lease" and not leased_macs[mac] then
					print("Adding %s to leases" % mac)
					add_lease(mac)
					leased_macs[mac] = true
				elseif cmd == "whitelist" and not whitelist_macs[mac] then
					print("Adding %s to whitelist" % mac)
					add_whitelist(mac)
					whitelist_macs[mac] = true
				elseif cmd == "blacklist" and not blacklist_macs[mac] then
					print("Adding %s to blacklist" % mac)
					add_blacklist(mac)
					blacklist_macs[mac] = true
				else
					print("The mac %s is already %sed" %{ mac, cmd })
				end
			elseif mac and cmd == "remove" then
				if leased_macs[mac] then
					print("Removing %s from leases" % mac)
					remove_lease(mac)
					leased_macs[mac] = nil
				elseif whitelist_macs[mac] then
					print("Removing %s from whitelist" % mac)
					remove_whitelist(mac)
					whitelist_macs[mac] = nil					
				elseif blacklist_macs[mac] then
					print("Removing %s from blacklist" % mac)
					remove_blacklist(mac)
					blacklist_macs[mac] = nil
				else
					print("The mac %s is not known" % mac)
				end
			else
				print("Can not find mac for ip %s" % argv[i])
			end
		end

		unlock()
		os.exit(0)	
	elseif cmd == "sync" then
		sync()
		os.exit(0)
	elseif cmd == "list" then
		list()
		os.exit(0)
	else
		print("Usage:")
		print("\n  luci-splash list\n    List connected, black- and whitelisted clients")
		print("\n  luci-splash sync\n    Synchronize firewall rules and clear expired leases")
		print("\n  luci-splash lease <MAC-or-IP>\n    Create a lease for the given address")
		print("\n  luci-splash blacklist <MAC-or-IP>\n    Add given address to blacklist")
		print("\n  luci-splash whitelist <MAC-or-IP>\n    Add given address to whitelist")
		print("\n  luci-splash remove <MAC-or-IP>\n    Remove given address from the lease-, black- or whitelist")
		print("")

		os.exit(1)	
	end
end

-- Get a list of known mac addresses
function get_known_macs(list)
	local leased_macs = { }

	if not list or list == "lease" then
		uci:foreach("luci_splash", "lease",
			function(s) leased_macs[s.mac:lower()] = true end)
	end

	if not list or list == "whitelist" then
		uci:foreach("luci_splash", "whitelist",
			function(s) leased_macs[s.mac:lower()] = true end)
	end

	if not list or list == "blacklist" then
		uci:foreach("luci_splash", "blacklist",
			function(s) leased_macs[s.mac:lower()] = true end)
	end

	return leased_macs
end


-- Get a list of known ip addresses
function get_known_ips(macs, arp)
	local leased_ips = { }
	if not macs then macs = get_known_macs() end
	for _, e in ipairs(arp or net.arptable()) do
		if macs[e["HW address"]:lower()] then leased_ips[e["IP address"]] = true end
	end
	return leased_ips
end


-- Helper to delete iptables rules
function ipt_delete_all(args, comp, off)
	off = off or { }
	for i, r in ipairs(ipt:find(args)) do
		if comp == nil or comp(r) then
			off[r.table] = off[r.table] or { }
			off[r.table][r.chain] = off[r.table][r.chain] or 0

			os.execute("iptables -t %q -D %q %d 2>/dev/null"
				%{ r.table, r.chain, r.index - off[r.table][r.chain] })

			off[r.table][r.chain] = off[r.table][r.chain] + 1
		end
	end
end


-- Add a lease to state and invoke add_rule
function add_lease(mac, arp, no_uci)
	mac = mac:lower()

	-- Get current ip address
	local ipaddr
	for _, entry in ipairs(arp or net.arptable()) do
		if entry["HW address"]:lower() == mac then
			ipaddr = entry["IP address"]
			break
		end
	end

	-- Add lease if there is an ip addr
	if ipaddr then
		if not no_uci then
			uci:section("luci_splash", "lease", nil, {
				mac    = mac,
				ipaddr = ipaddr,
				start  = os.time()
			})
			uci:save("luci_splash")
		end
		add_lease_rule(mac, ipaddr)
	else
		print("Found no active IP for %s, lease not added" % mac)
	end
end


-- Remove a lease from state and invoke remove_rule
function remove_lease(mac)
	mac = mac:lower()

	uci:delete_all("luci_splash", "lease",
		function(s)
			if s.mac:lower() == mac then
				remove_lease_rule(mac, s.ipaddr)
				return true
			end
			return false
		end)
		
	uci:save("luci_splash")
end


-- Add a whitelist entry
function add_whitelist(mac)
	uci:section("luci_splash", "whitelist", nil, { mac = mac })
	uci:save("luci_splash")
	uci:commit("luci_splash")
	add_whitelist_rule(mac)
end


-- Add a blacklist entry
function add_blacklist(mac)
	uci:section("luci_splash", "blacklist", nil, { mac = mac })
	uci:save("luci_splash")
	uci:commit("luci_splash")
	add_blacklist_rule(mac)
end


-- Remove a whitelist entry
function remove_whitelist(mac)
	mac = mac:lower()
	uci:delete_all("luci_splash", "whitelist",
		function(s) return not s.mac or s.mac:lower() == mac end)
	uci:save("luci_splash")
	uci:commit("luci_splash")
	remove_lease_rule(mac)
end


-- Remove a blacklist entry
function remove_blacklist(mac)
	mac = mac:lower()
	uci:delete_all("luci_splash", "blacklist",
		function(s) return not s.mac or s.mac:lower() == mac end)
	uci:save("luci_splash")
	uci:commit("luci_splash")
	remove_lease_rule(mac)
end


-- Add an iptables rule
function add_lease_rule(mac, ipaddr)
	if limit_up > 0 and limit_down > 0 then
		os.execute("iptables -t mangle -I luci_splash_mark_out -m mac --mac-source %q -j MARK --set-mark 79" % mac)
		os.execute("iptables -t mangle -I luci_splash_mark_in -d %q -j MARK --set-mark 80" % ipaddr)
	end

	os.execute("iptables -t filter -I luci_splash_filter -m mac --mac-source %q -j RETURN" % mac)
	os.execute("iptables -t nat    -I luci_splash_leases -m mac --mac-source %q -j RETURN" % mac)
end


-- Remove lease, black- or whitelist rules
function remove_lease_rule(mac, ipaddr)
	ipt:resync()

	if ipaddr then
		ipt_delete_all({table="mangle", chain="luci_splash_mark_in",  destination=ipaddr})
		ipt_delete_all({table="mangle", chain="luci_splash_mark_out", options={"MAC", mac:upper()}})
	end

	ipt_delete_all({table="filter", chain="luci_splash_filter",   options={"MAC", mac:upper()}})
	ipt_delete_all({table="nat",    chain="luci_splash_leases",   options={"MAC", mac:upper()}})
end


-- Add whitelist rules
function add_whitelist_rule(mac)
	os.execute("iptables -t filter -I luci_splash_filter -m mac --mac-source %q -j RETURN" % mac)
	os.execute("iptables -t nat    -I luci_splash_leases -m mac --mac-source %q -j RETURN" % mac)
end


-- Add blacklist rules
function add_blacklist_rule(mac)
	os.execute("iptables -t filter -I luci_splash_filter -m mac --mac-source %q -j DROP" % mac)
	os.execute("iptables -t nat    -I luci_splash_leases -m mac --mac-source %q -j DROP" % mac)
end


-- Synchronise leases, remove abandoned rules
function sync()
	lock()

	local time = os.time()

	-- Current leases in state files
	local leases = uci:get_all("luci_splash")
	
	-- Convert leasetime to seconds
	local leasetime = tonumber(uci:get("luci_splash", "general", "leasetime")) * 3600
	
	-- Clean state file
	uci:load("luci_splash")
	uci:revert("luci_splash")
	
	-- For all leases
	for k, v in pairs(leases) do
		if v[".type"] == "lease" then
			if os.difftime(time, tonumber(v.start)) > leasetime then
				-- Remove expired
				remove_lease_rule(v.mac, v.ipaddr)
			else
				-- Rewrite state
				uci:section("luci_splash", "lease", nil, {		
					mac    = v.mac,
					ipaddr = v.ipaddr,
					start  = v.start
				})
			end
		end
	end

	uci:save("luci_splash")

	-- Get current IPs and MAC addresses
	local macs = get_known_macs()
	local ips  = get_known_ips(macs)

	ipt:resync()

	ipt_delete_all({table="filter", chain="luci_splash_filter", options={"MAC"}},
		function(r) return not macs[r.options[2]:lower()] end)

	ipt_delete_all({table="nat", chain="luci_splash_leases", options={"MAC"}},
		function(r) return not macs[r.options[2]:lower()] end)

	ipt_delete_all({table="mangle", chain="luci_splash_mark_out", options={"MAC", "MARK", "set"}},
		function(r) return not macs[r.options[2]:lower()] end)

	ipt_delete_all({table="mangle", chain="luci_splash_mark_in", options={"MARK", "set"}},
		function(r) return not ips[r.destination] end)

	unlock()
end

-- Show client info
function list()
	-- Get current arp cache
	local arpcache = { }
	for _, entry in ipairs(net.arptable()) do
		arpcache[entry["HW address"]:lower()] = { entry["Device"]:lower(), entry["IP address"]:lower() }
	end

	-- Find traffic usage
	local function traffic(lease)
		local traffic_in  = 0
		local traffic_out = 0

		local rin  = ipt:find({table="mangle", chain="luci_splash_mark_in", destination=lease.ipaddr})
		local rout = ipt:find({table="mangle", chain="luci_splash_mark_out", options={"MAC", lease.mac:upper()}})

		if rin  and #rin  > 0 then traffic_in  = math.floor( rin[1].bytes / 1024) end
		if rout and #rout > 0 then traffic_out = math.floor(rout[1].bytes / 1024) end

		return traffic_in, traffic_out
	end

	-- Print listings
	local leases = uci:get_all("luci_splash")

	print(string.format(
		"%-17s  %-15s  %-9s  %-4s  %-7s  %20s",
		"MAC", "IP", "State", "Dur.", "Intf.", "Traffic down/up"
	))

	-- Leases
	for _, s in pairs(leases) do
		if s[".type"] == "lease" and s.mac then
			local ti, to = traffic(s)
			local mac = s.mac:lower()
			local arp = arpcache[mac]
			print(string.format(
				"%-17s  %-15s  %-9s  %3dm  %-7s  %7dKB  %7dKB",
				mac, s.ipaddr, "leased",
				math.floor(( os.time() - tonumber(s.start) ) / 60),
				arp and arp[1] or "?", ti, to
			))
		end
	end

	-- Whitelist, Blacklist
	for _, s in luci.util.spairs(leases,
		function(a,b) return leases[a][".type"] > leases[b][".type"] end
	) do
		if (s[".type"] == "whitelist" or s[".type"] == "blacklist") and s.mac then
			local mac = s.mac:lower()
			local arp = arpcache[mac]
			print(string.format(
				"%-17s  %-15s  %-9s  %4s  %-7s  %9s  %9s",
				mac, arp and arp[2] or "?", s[".type"],
				"- ", arp and arp[1] or "?", "-", "-"
			))
		end
	end
end

main(arg)
