src/Main.hs: fix handling of "domain not found" errors.

[haeredes.git] / src / Main.hs

diff --git a/src/Main.hs b/src/Main.hs
index f7a56ea5fbdf3fd8b6d50f4b2316396a3afd16f6..c93697a0c7d565e431201a56c7d851e10d1f4f2e 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,4 +1,4 @@
-module Main
+module Main (main)
 where
 
 import Control.Concurrent.ParallelIO.Global (
@@ -9,9 +9,9 @@ import qualified Data.ByteString.Char8 as BS (
   getContents,
   pack,
   words )
-import Data.List ( (\\) )
-import Data.String.Utils (join)
+import Data.List ( (\\), intersperse )
 import Network.DNS (
+  DNSError(NameError),
   Domain,
   FileOrNumericHost(RCHostName),
   ResolvConf(resolvInfo, resolvTimeout),
@@ -53,15 +53,18 @@ report :: [Domain] -- ^ The list of @delgts@
        -> LookupResult
        -> IO ()
 
--- If the lookup resulted in a DNS error, we just ignore the whole
--- thing.
-report _ _ (_, Left _) = return ()
-
 -- If the lookup succeeded but there were no results, report that the
--- domain is not delegated.
-report _ _ (d, Right []) =
+-- domain is not delegated. Note that the behavior of the DNS library
+-- changed with regard to this at some point: we used to get back
+-- a "success," but with an empty list of results. Now a NameError
+-- (which is not actually an error!) is returned.
+report _ _ (d, Left NameError) =
   putStrLn $ "Domain " ++ (show d) ++ " not delegated."
 
+-- If the lookup resulted in some other DNS error, we just ignore the
+-- whole thing.
+report _ _ (_, Left _) = return ()
+
 -- Otherwise, subtract our delegates from the list of results and
 -- report the leftovers.
 report delgts normalize_function (d, Right raw_hosts) = do
@@ -72,6 +75,11 @@ report delgts normalize_function (d, Right raw_hosts) = do
                (show d) ++
                " delegates somewhere else: " ++
                (join " " (map show leftovers))
+  where
+    -- Create one big string by joining together a list of smaller
+    -- strings and placing a delimiter between them.
+    join :: String -> [String] -> String
+    join delimiter strings = concat (intersperse delimiter strings)
 
 
 main :: IO ()