{-# LANGUAGE CPP #-}
module Network.DNS.Resolver.Internal (
getDefaultDnsServers
) where
import Network.DNS.Imports
#if !defined(mingw32_HOST_OS)
#define POSIX
#else
#define WIN
#endif
#if defined(WIN)
import Foreign.C.String
import Foreign.Marshal.Alloc (allocaBytes)
#else
import Data.Char (isSpace)
#endif
getDefaultDnsServers :: FilePath -> IO [String]
#if defined(WIN)
foreign import ccall "getWindowsDefDnsServers" getWindowsDefDnsServers :: CString -> Int -> IO Word32
getDefaultDnsServers _ = do
allocaBytes 256 $ \cString -> do
res <- getWindowsDefDnsServers cString 256
case res of
0 -> split ',' <$> peekCString cString
_ -> return []
where
split :: Char -> String -> [String]
split c cs =
let (h, t) = dropWhile (== c) <$> break (== c) cs
in if null t
then if null h then [] else [h]
else if null h
then split c t
else h : split c t
#else
getDefaultDnsServers :: FilePath -> IO [FilePath]
getDefaultDnsServers FilePath
file = FilePath -> [FilePath]
toAddresses forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> FilePath -> IO FilePath
readFile FilePath
file
where
toAddresses :: String -> [String]
toAddresses :: FilePath -> [FilePath]
toAddresses FilePath
cs = forall a b. (a -> b) -> [a] -> [b]
map FilePath -> FilePath
extract (forall a. (a -> Bool) -> [a] -> [a]
filter (FilePath
"nameserver" forall a. Eq a => [a] -> [a] -> Bool
`isPrefixOf`) (FilePath -> [FilePath]
lines FilePath
cs))
extract :: FilePath -> FilePath
extract = forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> [a]
dropWhile Char -> Bool
isSpace forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> [a]
dropWhile Char -> Bool
isSpace forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. Int -> [a] -> [a]
drop Int
11
#endif