util.lua

#!/usr/bin/lua
local uci = require('simple-uci').cursor()
local util = require 'gluon.util'
local iwinfo = require 'iwinfo'
local json = require 'jsonc'
local bit = require 'bit32'
local log = require 'posix.syslog'
local M = {}
local fcntl = require 'posix.fcntl'
local unistd = require 'posix.unistd'
local sys_sock = require "posix.sys.socket"
local domains = {"stuttgart.freifunk.net", "freifunk-stuttgart.net"}

function M.log(dest, msg)
	local prefix = 'ffs-set-segment: '
	msg = prefix .. msg
	if dest == 'out' then
		io.stdout:write(msg .. '\n')
		log.syslog(log.LOG_INFO, msg)
	elseif dest == 'err' then
		io.stderr:write(msg .. '\n')
		log.syslog(log.LOG_CRIT, msg)
	end
end

function M.fastd_public_key()
	local key = util.trim(util.exec('/etc/init.d/fastd show_key mesh_vpn'))

	if key == '' then key = nil end

	return key
end

function M.lock(lockfilename)
	local lockfd, err = fcntl.open(lockfilename, bit.bor(fcntl.O_WRONLY, fcntl.O_CREAT), 384) -- mode 0600
	if not lockfd then
		autil.log('err', err)
		local err_verbose = string.format("Unable to get file descriptor for lock file %s .", lockfilename)
		autil.log('err', err_verbose)
		os.exit(1)
	end

	local ok, _ = fcntl.fcntl(lockfd, fcntl.F_SETLK, {
		l_start = 0,
		l_len = 0,
		l_type = fcntl.F_WRLCK,
		l_whence = unistd.SEEK_SET,
	})
	if not ok then
		local err_msg = string.format("Unable to lock file %s. ", lockfilename) ..
			"Make sure there is no other instance of this script running."
		M.log('err', err_msg)
		os.exit(1)
	end
end

local function execute(command)
        local f = io.popen(command)
        if not f then
                return nil
        end

        local data = f:read('*a')
        f:close()
        return data
end

function M.has_batman_gw()
	
	local gwl_cmd = execute("batctl meshif bat0 gateways_json")
	if not gwl_cmd then
		M.log("err", "could not get gwl")
		return false
	end
	local gwl = json.parse(gwl_cmd)
	if not gwl then
		return false
	end

	return true

end

local function _resp_try_v6(dnsrecords)
	if not dnsrecords then
		return nil
	end

	for i, record in ipairs(dnsrecords) do
		local addr = record.addr
		local segmentstr = addr:match("^2001:2:0:711::([0-9]+)")

		if segmentstr then
			local segment = tonumber(segmentstr, 10)
			if not segment then
				M.log("err", "Could not convert '"..segmentstr.."' to segment")
				return nil
			end
			return segment
		end
	end
end

local function _resp_try_v4(dnsrecords)
	if not dnsrecords then
		return nil
	end

	for i, record in ipairs(dnsrecords) do
		local addr = record.addr
		local segmentstr = addr:match('^198.18.190.([0-9]+)')

		if segmentstr then
			local segment = tonumber(segmentstr, 10)
			if segment == nil then
				M.log("err", "Could not convert '"..addr.addr.."' to segment")
				return nil
			end
			return segment
		end
	end
end

function M.get_segment_from_dns(nodeid, pubkey)
	for i, domain in ipairs(domains) do
		local dnsname = "ffs-" .. nodeid .. "-" .. pubkey .. ".segassign." .. domain
		M.log("out", "DNS for "..dnsname)
	
		--- todo: we need to specify to use WAN DNS servers somehow, current idea: just run us with gluon-wan always
		local dnsres, errmsg, errno = sys_sock.getaddrinfo(dnsname)

		if not dnsres then
			M.log("err", "DNS for '"..dnsname.."' failed: "..errno.." "..errmsg)
		else
			local segment = _resp_try_v6(dnsres)
			if not segment then
				M.log("err", "Could not get segment based of AAAA records on '"..dnsname.."', trying fallback to A record")
				segment = _resp_try_v4(dnsres)
				if not segment then
					M.log("err", "A record fallback failed for '"..dnsname.."'")
					return nil
				end
			end
			return segment
		end

	end
end

function M.get_segment_from_batman()
	local gwl = json.parse(execute("batctl meshif bat0 gateways_json", "r"))
	if not gwl then
		return nil
	end

	for i, gw in ipairs(gwl) do
		local gwmac = gw.orig_address
		-- valid GW mac, byte index 4 is the segment
		local batseg = gwmac:match("02:00:3[0-9a-fA-F]:([0-9a-fA-F]-):") 
		if not batseg then
			return nil
		end
		return tonumber(batseg, 10)
	end
end

local function is_in_table(haystack, needle)
	for i, item in ipairs(haystack) do
		if item == needle then
			return true
		end
	end
	return false
end

local function restart_fastd()
	M.log("out", "Restarting fastd")
	io.popen("/etc/init.d/fastd restart")
	io.popen("/sbin/ip addr flush dev br-client scope global")
end

function M.set_fastd_remotes(port, segment)
	local changed = false
	for i=1,10 do
		local gwid = string.format("gw%02d", i)
		local current_peer_list = uci:get_list("fastd", "mesh_vpn_backbone_peer_" .. gwid, "remote")

		local newpeers = {}
		for _, domain in ipairs(domains) do
			local peer = string.format("\"gw%02ds%02d.gw.%s\" port %d", i, segment, domain, port)
			table.insert(newpeers, peer)

			if not is_in_table(current_peer_list, peer) then
				changed = true
			end
		end
		if changed then
			uci:set_list("fastd", "mesh_vpn_backbone_peer_" .. gwid, "remote", newpeers)
		end
	end
	if changed then
		uci:save('fastd')
		restart_fastd()
	else
		M.log("out", "No changes")
	end

end

return M