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|
{-# 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 ',' <$> peekCString cString
_ -> return [] -- TODO: Do proper error handling here.
where
split :: Char -> String -> [String]
split c cs =
let (h, t) = dropWhile (== c) <$> 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 file = toAddresses <$> readFile file
where
toAddresses :: String -> [String]
toAddresses cs = map extract (filter ("nameserver" `isPrefixOf`) (lines cs))
extract = reverse . dropWhile isSpace . reverse . dropWhile isSpace . drop 11
#endif
|
