Support hostnames as --server arguments.

[haeredes.git] / src / DNS.hs

diff --git a/src/DNS.hs b/src/DNS.hs
index f649e0ad5da96ea4c8ab34b250eeaf9ab2948044..a1ed2bdf718790d5fce2aaa77cda275da77eb3f1 100644 (file)
--- a/src/DNS.hs
+++ b/src/DNS.hs
@@ -2,10 +2,11 @@ module DNS (
   LookupResult,
   lookupMX',
   lookupNS',
-  normalize
-  )
+  normalize,
+  resolve_address )
 where
 
+import Control.Applicative ((<$>))
 import Control.Monad (liftM)
 import qualified Data.ByteString.Char8 as BS (
   append,
@@ -13,14 +14,61 @@ import qualified Data.ByteString.Char8 as BS (
   map,
   pack )
 import Data.Char (toLower)
+import Data.IP (IPv4)
 import Network.DNS (
   Domain,
+  DNSFormat(..),
   Resolver,
+  RDATA(..),
+  TYPE(..),
+  defaultResolvConf,
+  lookupA,
   lookupMX,
-  lookupNS )
+  lookupNS,
+  lookupRaw,
+  makeResolvSeed,
+  rdata,
+  rrtype,
+  withResolver )
+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"
+
+resolve_address :: String -> IO (Maybe IPv4)
+resolve_address s =
+  case read_result of
+    Just _  -> return read_result
+    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
+  where
+    read_result :: Maybe IPv4
+    read_result = readMaybe s
+
 lookupMX' :: Resolver -> Domain -> IO LookupResult
 lookupMX' resolver domain =
   liftM (pair_em . drop_priority) $ lookupMX resolver domain
@@ -33,12 +81,20 @@ lookupMX' resolver domain =
 
 -- This function keeps the domain matches with its NS records.
 lookupNS' :: Resolver -> Domain -> IO LookupResult
-lookupNS' resolver domain =
-  liftM pair_em $ lookupNS resolver domain
+lookupNS' resolver domain = do
+  answer_result <- lookupNS resolver domain
+  auth_result <- lookupNS_authority 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)
+
 -- | Normalize the given name by lowercasing and appending a trailing
 --   dot (the root) if necessary.
 normalize :: Domain -> Domain