bracketOnError
        :: IO a         -- ^ computation to run first (\"acquire resource\")
        -> (a -> IO b)  -- ^ computation to run last (\"release resource\")
        -> (a -> IO c)  -- ^ computation to run in-between
        -> IO c         -- returns the value from the in-between computation
bracketOnError before after thing =
  mask $ \restore -> do
    a <- before
    restore (thing a) `onException` after a

      bracket
        (do ret <- c_getaddrinfo c_node c_service c_hints ptr_ptr_addrs
            ptr_addrs <- if ret == 0
                         then peek ptr_ptr_addrs
                         else return nullPtr
            return (ret, ptr_addrs)
        )
        (\(ret, ptr_addrs) -> do
            -- Don't call freeaddrinfo with NULL, it segfaults on some
            -- platforms.
            when (ret == 0) $ c_freeaddrinfo ptr_addrs
        )
        (\(ret, ptr_addrs) ->
           if ret == 0
           then followAddrInfo ptr_addrs
           else do
             err <- gai_strerror ret
             ioError $ ioeSetErrorString
               (mkIOError NoSuchThing message Nothing Nothing)
               err
        )

getAddrs = do
    ret <- c_getaddrinfo c_node c_service c_hints
    if ret == 0
        then Right <$> peek ptr_ptr_addrs
        else pure $ Left ret

addrErr ret = do
    err <- gai_strerror ret
    ioError $ ioeSetErrorString
        (mkIOError NoSuchThing message Nothing Nothing)
        err

bracket
    getAddrs 
    (mapM_ c_freeaddrinfo)
    (either addrErr followAddrInfo)