daemon/lua: kB/MB/GB in env, net.iface sugar, env

daemon/lua/config.lua

 -- Default configuration
-cache.open('.', 10485760)
+cache.open(10*MB)
+-- Listen on localhost
+if not next(net.list()) then
+	if not pcall(net.listen, '127.0.0.1') then
+		error('failed to bind to localhost#53')
+	end
+end
\ No newline at end of file

daemon/lua/sandbox.lua

+-- Units
+kB = 1024
+MB = 1024*1024
+GB = 1024*1024
+
+-- Function aliases
+-- `env.VAR returns os.getenv(VAR)`
+env = {}
+setmetatable(env, {
+	__index = function (t, k) return os.getenv(k) end
+})
+
+-- Quick access to interfaces
+-- `net.<iface>` => `net.interfaces()[iface]`
+setmetatable(net, {
+	__index = function (t, k)
+		local v = rawget(t, k)
+		if v then return v
+		else return net.interfaces()[k]
+		end
+	end
+})
+
 -- Syntactic sugar for module loading
 -- `modules.<name> = <config>`
 setmetatable(modules, {