{-# LANGUAGE CPP #-}
-- | Only allow local connections.
--
module Network.Wai.Middleware.Local
    ( local
    ) where

import Network.Socket (SockAddr (..))
import Network.Wai (Middleware, Response, remoteHost)

-- | This middleware rejects non-local connections with a specific response.
--   It is useful when supporting web-based local applications, which would
--   typically want to reject external connections.

local :: Response -> Middleware
local resp f r k = case remoteHost r of
                   SockAddrInet _  h | h == fromIntegral home
                                    -> f r k
#if !defined(mingw32_HOST_OS) && !defined(_WIN32)
                   SockAddrUnix _   -> f r k
#endif
                   _                ->  k resp
 where
        home :: Integer
        home = 127 + (256 * 256 * 256)