module DNS ( lookup_mxs )
where

import Network.DNS (
  Domain,
  defaultResolvConf,
  lookupMX,
  makeResolvSeed,
  withResolver )

-- Slow since we create the resolver every time.
lookup_mxs :: Domain -> IO [Domain]
lookup_mxs domain = do
  default_rs <- makeResolvSeed defaultResolvConf
  withResolver default_rs $ \resolver -> do
    mxs <- lookupMX resolver domain
    return $ case mxs of
               Left  _     -> []
               Right pairs -> map fst pairs