From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 13 Sep 2013 13:35:40 +0000 (-0400)
Subject: Update code and doctests to support the new version of the dns library.
X-Git-Tag: 0.2.0~2
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=689bda2499ec821772b456cb7982527d6740649f;p=haeredes.git

Update code and doctests to support the new version of the dns library.
---

diff --git a/src/DNS.hs b/src/DNS.hs
index 61b96aa..34a8bd1 100644
--- a/src/DNS.hs
+++ b/src/DNS.hs
@@ -9,7 +9,6 @@ module DNS (
   resolve_address )
 where
 
-import Control.Applicative ((<$>))
 import Control.Monad (liftM)
 import qualified Data.ByteString.Char8 as BS (
   append,
@@ -21,18 +20,14 @@ import Data.Char (toLower)
 import Data.IP (IPv4)
 import Network.DNS (
   Domain,
-  DNSFormat(..),
+  DNSError,
   Resolver,
-  RDATA(..),
-  TYPE(..),
   defaultResolvConf,
   lookupA,
   lookupMX,
   lookupNS,
-  lookupRaw,
+  lookupNSAuth,
   makeResolvSeed,
-  rdata,
-  rrtype,
   withResolver )
 import Test.Framework (Test, testGroup)
 import Test.Framework.Providers.HUnit (testCase)
@@ -40,52 +35,28 @@ import Test.Framework.Providers.QuickCheck2 (testProperty)
 import Test.HUnit (assertEqual)
 import Text.Read (readMaybe)
 
-type LookupResult = (Domain, Maybe [Domain])
-
--- | Perform a query, but take the result from the authority section
---   of the response rather than the answer section. Code shamelessly
---   stolen from Network.DNS.lookup.
-lookup_authority :: Resolver -> Domain -> TYPE -> IO (Maybe [RDATA])
-lookup_authority rlv dom typ = (>>= toRDATA) <$> lookupRaw rlv dom typ
-  where
-    correct r = rrtype r == typ
-    listToMaybe [] = Nothing
-    listToMaybe xs = Just xs
-    toRDATA = listToMaybe . map rdata . filter correct . authority
-
--- | Like lookupNS, except we take the result from the authority
---   section of the response (as opposed to the answer section).
-lookupNS_authority :: Resolver -> Domain -> IO (Maybe [Domain])
-lookupNS_authority rlv dom = toNS <$> DNS.lookup_authority rlv dom NS
-  where
-    toNS = fmap (map unTag)
-    unTag (RD_NS dm) = dm
-    unTag _ = error "lookupNS_authority"
-
+type LookupResult = (Domain, Either DNSError [Domain])
 
 -- | Takes a String representing either a hostname or an IP
 --   address. If a hostname was supplied, it is resolved to either an
---   IPv4 or Nothing. If an IP address is supplied, it is returned as an
---   IPv4.
+--   [IPv4] or an error. If an IP address is supplied, it is returned
+--   as a singleton [IPv4].
 --
 --   Examples:
 --
 --   >>> resolve_address "example.com"
---   Just 93.184.216.119
+--   Right [93.184.216.119]
 --   >>> resolve_address "93.184.216.119"
---   Just 93.184.216.119
+--   Right [93.184.216.119]
 --
-resolve_address :: String -> IO (Maybe IPv4)
+resolve_address :: String -> IO (Either DNSError [IPv4])
 resolve_address s =
   case read_result of
-    Just _  -> return read_result
+    Just addr  -> return $ Right [addr]
     Nothing -> do
       default_rs <- makeResolvSeed defaultResolvConf
-      withResolver default_rs $ \resolver -> do
-        result <- lookupA resolver (BS.pack s)
-        return $ case result of
-                   Just (x:_) -> Just x
-                   _           -> Nothing
+      withResolver default_rs $ \resolver ->
+        lookupA resolver (BS.pack s)
   where
     read_result :: Maybe IPv4
     read_result = readMaybe s
@@ -102,13 +73,14 @@ resolve_address s =
 --   >>> rs <- makeResolvSeed defaultResolvConf
 --   >>> let domain = BS.pack "example.com."
 --   >>> withResolver rs $ \resolver -> lookupMX' resolver domain
---   ("example.com.",Nothing)
+--   ("example.com.",Right [])
 --
 lookupMX' :: Resolver -> Domain -> IO LookupResult
 lookupMX' resolver domain =
   liftM (pair_em . drop_priority) $ lookupMX resolver domain
   where
-    drop_priority :: Maybe [(Domain, Int)] -> Maybe [Domain]
+    drop_priority :: Either DNSError [(Domain, Int)]
+                  -> Either DNSError [Domain]
     drop_priority = fmap (map fst)
 
     pair_em :: a -> (Domain, a)
@@ -126,26 +98,30 @@ lookupMX' resolver domain =
 --   them to get a reliable result.
 --
 --   >>> import Data.List (sort)
+--   >>> import Control.Applicative ((<$>))
+--   >>>
 --   >>> let sort_snd (x,y) = (x, sort <$> y)
 --   >>> rs <- makeResolvSeed defaultResolvConf
 --   >>> let domain = BS.pack "example.com."
 --   >>> withResolver rs $ \resolver -> sort_snd <$> lookupNS' resolver domain
---   ("example.com.",Just ["a.iana-servers.net.","b.iana-servers.net."])
+--   ("example.com.",Right ["a.iana-servers.net.","b.iana-servers.net."])
 --
 lookupNS' :: Resolver -> Domain -> IO LookupResult
 lookupNS' resolver domain = do
   answer_result <- lookupNS resolver domain
-  auth_result <- lookupNS_authority resolver domain
+  auth_result <- lookupNSAuth resolver domain
   liftM pair_em $ return $ combine answer_result auth_result
   where
     pair_em :: a -> (Domain, a)
     pair_em = (,) domain
 
-    combine :: (Maybe [Domain]) ->  (Maybe [Domain]) -> (Maybe [Domain])
-    combine Nothing Nothing = Nothing
-    combine m1 Nothing = m1
-    combine Nothing m2 = m2
-    combine (Just ds1) (Just ds2) = Just (ds1 ++ ds2)
+    combine :: (Either DNSError [Domain])
+            -> (Either DNSError [Domain])
+            -> (Either DNSError [Domain])
+    combine e1 e2 = do
+      l1 <- e1
+      l2 <- e2
+      return (l1 ++ l2)
 
 -- | Perform both normalize_case and normalize_root.
 normalize :: Domain -> Domain
diff --git a/src/Main.hs b/src/Main.hs
index 4e0da6b..a5dc794 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -34,14 +34,31 @@ import ExitCodes (exit_bad_server)
 import Timeout (Timeout(..))
 
 
--- | Report results for this LookupResult. If there's a Nothing 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 "cleaning"), we report those as well.
-report :: LookupResult -> IO ()
-report (d, Nothing) =
+-- | 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.
+--
+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 []) =
   putStrLn $ "Domain " ++ (show d) ++ " not delegated."
-report (d, Just leftovers) =
+
+-- Otherwise, subtract our delegates from the list of results and
+-- report the leftovers.
+report delgts (d, Right hosts) = do
+  let leftovers = hosts \\ delgts
   unless (null leftovers) $
     putStrLn $ "Domain " ++
                (show d) ++
@@ -49,19 +66,6 @@ report (d, Just leftovers) =
                (join " " (map show leftovers))
 
 
--- | "Clean" a lookup result by subtracting out the list of delegates.
---   There shouldn't be anything left over. If there were no lookup
---   results, we leave the Nothing in place so that 'report' can
---   pattern match on it.
-clean :: [Domain] -- ^ List of delegates, @ds@
-      -> LookupResult
-      -> LookupResult
-clean _ p@(_, Nothing) = p
-clean delgts (d, Just targets) =
-  (d, Just $ targets \\ delgts)
-
-
-
 main :: IO ()
 main = do
   cfg <- get_args
@@ -89,16 +93,20 @@ main = do
            Just s -> do
              s' <- resolve_address s
              case s' of
-               Nothing -> do
-                 hPutStrLn stderr ("Bad DNS server or lookup error: " ++ s)
+               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)
-               Just s'' ->
+               Right (srv:_) ->
                  return $ defaultResolvConf { resolvInfo =
-                                                RCHostName (show s'') }
+                                                RCHostName (show srv) }
 
   -- Set the timeout from the command line. The resolvTimeout field is
   -- in microseconds, so we multiply by one million.
-  let rc = rc' { resolvTimeout = 1000 * 1000 * (seconds $ timeout cfg) }
+  let rc = rc' { resolvTimeout = 1000 * 1000 * seconds (timeout cfg) }
   rs <- makeResolvSeed rc
 
   let lookup_function = case cfg of
@@ -109,7 +117,6 @@ main = do
          -- Bad stuff happens if we try to run these lookups in parallel
          -- instead of the reports.
          records <- mapM (lookup_function resolver) nrml_domains
-         let cleaned_records = map (clean nrml_delegates) records
-         parallel (map report cleaned_records)
+         parallel (map (report nrml_delegates) records)
 
   stopGlobalPool