src/Main.hs: add an explicit export list to silence a GHC warning.

[haeredes.git] / src / Main.hs

diff --git a/src/Main.hs b/src/Main.hs
index b141e302f8298e50ef10600616b3084b64cc6c18..89d2cd56d1a2aeaca07420d403e2e29da1e7abfe 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,6 +1,142 @@
-module Main
+module Main (main)
 where
 
+import Control.Concurrent.ParallelIO.Global (
+  parallelInterleaved,
+  stopGlobalPool )
+import Control.Monad (unless)
+import qualified Data.ByteString.Char8 as BS (
+  getContents,
+  pack,
+  words )
+import Data.List ( (\\), intersperse )
+import Network.DNS (
+  Domain,
+  FileOrNumericHost(RCHostName),
+  ResolvConf(resolvInfo, resolvTimeout),
+  defaultResolvConf,
+  makeResolvSeed,
+  normalize,
+  normalizeCase,
+  withResolver )
+import System.Exit (ExitCode(ExitFailure), exitWith)
+import System.IO (hPutStrLn, stderr)
+
+import CommandLine (
+   Args(NS,MX,delegates,no_append_root,server,timeout),
+   get_args)
+import DNS (
+  LookupResult,
+  lookupMX',
+  lookupNS',
+  resolve_address )
+import ExitCodes (exit_bad_server)
+import Timeout (Timeout(seconds))
+
+
+-- | Given a list of delegates, report results for this
+--   'LookupResult'.
+--
+--   If there's an empty list in the second component, there were no
+--   query results, so we report that the domain was not delegated. If
+--   there were some results and there are leftovers (after removing
+--   the delegates), we report those as well.
+--
+--   Before processing, all names are normalized using the supplied
+--   function @normalize_function@. Ideally this should be the same
+--   function applied to the user-input names.
+--
+report :: [Domain] -- ^ The list of @delgts@
+       -> (Domain -> Domain) -- ^ Domain name normalization function,
+                             --   @normalize_function@.
+       -> 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 []) =
+  putStrLn $ "Domain " ++ (show d) ++ " not delegated."
+
+-- Otherwise, subtract our delegates from the list of results and
+-- report the leftovers.
+report delgts normalize_function (d, Right raw_hosts) = do
+  let nrml_hosts = map normalize_function raw_hosts
+  let leftovers = nrml_hosts \\ delgts
+  unless (null leftovers) $
+    putStrLn $ "Domain " ++
+               (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 ()
 main = do
-  putStrLn "Hello, World."
+  cfg <- get_args
+
+  -- This reads stdin.
+  input <- BS.getContents
+
+  -- Split the input on any whitespace characters.
+  let raw_domains = BS.words input
+
+  -- Convert these to ByteStrings.
+  let raw_delegates = map BS.pack (delegates cfg)
+
+  let normalize_function =
+        if (no_append_root cfg)
+        then normalizeCase
+        else normalize
+
+  -- Normalize the given names and delegates
+  let nrml_domains   = map normalize_function raw_domains
+  let nrml_delegates = map normalize_function raw_delegates
+
+  rc' <- case (server cfg) of
+           Nothing -> return defaultResolvConf
+           Just s -> do
+             s' <- resolve_address s
+             case s' of
+               Left err -> do
+                 let errmsg = show err
+                 hPutStrLn stderr ("Bad DNS server or lookup error: " ++ errmsg)
+                 exitWith (ExitFailure exit_bad_server)
+               Right []  -> do
+                 hPutStrLn stderr ("Hostname " ++ s ++ " has no 'A' records.")
+                 exitWith (ExitFailure exit_bad_server)
+               Right (srv:_) ->
+                 return $ defaultResolvConf { resolvInfo =
+                                                RCHostName (show srv) }
+
+  -- Set the timeout from the command line. The resolvTimeout field is
+  -- in microseconds, so we multiply by one million.
+  let a_million = 1000 * 1000 :: Int
+  let rc = rc' { resolvTimeout = a_million * seconds (timeout cfg) }
+  rs <- makeResolvSeed rc
+
+  let lookup_function = case cfg of
+                          NS{} -> lookupNS'
+                          MX{} -> lookupMX'
+
+  let lookup' d = withResolver rs $ \resolver ->
+                    lookup_function resolver d
+
+  -- Construct a list of [IO whatever]. The withResolver calls
+  -- are the ones that should be run in parallel.
+  let actions = map lookup' nrml_domains
+
+  -- Run the lookup actions in parallel.
+  results <- parallelInterleaved actions
+
+  -- Output the results.
+  _ <- mapM (report nrml_delegates normalize_function) results
+
+  stopGlobalPool