split NmcTransform from NmcDom

[pdns-pipe-nmc.git] / NmcTransform.hs

diff --git a/NmcTransform.hs b/NmcTransform.hs
new file mode 100644 (file)
index 0000000..29c0008
--- /dev/null
+++ b/NmcTransform.hs
@@ -0,0 +1,129 @@
+module NmcTransform ( seedNmcDom
+                    , descendNmcDom
+                    ) where
+
+import Prelude hiding (lookup)
+import Data.ByteString.Lazy (ByteString)
+import Data.Map (lookup, delete, size)
+import Control.Monad (foldM)
+import Data.Aeson (decode)
+
+import NmcDom
+
+-- | Perform query and return error string or parsed domain object
+queryNmcDom ::
+  (String -> IO (Either String ByteString)) -- ^ query operation action
+  -> String                                 -- ^ key
+  -> IO (Either String NmcDom)              -- ^ error string or domain
+queryNmcDom queryOp key = do
+  l <- queryOp key
+  case l of
+    Left estr -> return $ Left estr
+    Right str -> case decode str :: Maybe NmcDom of
+      Nothing  -> return $ Left $ "Unparseable value: " ++ (show str)
+      Just dom -> return $ Right dom
+
+-- | Try to fetch "import" object and merge it into the base domain
+--   Original "import" element is removed, but new imports from the
+--   imported objects are processed recursively until there are none.
+mergeImport ::
+  (String -> IO (Either String ByteString)) -- ^ query operation action
+  -> Int                                    -- ^ recursion counter
+  -> NmcDom                                 -- ^ base domain
+  -> IO (Either String NmcDom)              -- ^ result with merged import
+mergeImport queryOp depth base = do
+  let
+    mbase = mergeSelf base
+    base' = mbase {domImport = Nothing}
+  -- print base
+  if depth <= 0 then return $ Left "Nesting of imports is too deep"
+  else case domImport mbase of
+    Nothing  -> return $ Right base'
+    Just keys -> foldM mergeImport1 (Right base') keys
+      where
+        mergeImport1 (Left  err) _   = return $ Left err
+        mergeImport1 (Right acc) key = do
+          sub <- queryNmcDom queryOp key
+          case sub of
+            Left  err  -> return $ Left err
+            Right sub' -> mergeImport queryOp (depth - 1) $
+                                sub' `mergeNmcDom` acc
+
+-- | If there is an element in the map with key "", merge the contents
+--   and remove this element. Do this recursively.
+mergeSelf :: NmcDom -> NmcDom
+mergeSelf base =
+  let
+    map   = domMap base
+    base' = base {domMap = removeSelf map}
+    removeSelf Nothing    = Nothing
+    removeSelf (Just map) = if size map' == 0 then Nothing else Just map'
+      where map' = delete "" map
+  in
+    case map of
+      Nothing   -> base'
+      Just map' ->
+        case lookup "" map' of
+          Nothing  -> base'
+          Just sub -> (mergeSelf sub) `mergeNmcDom` base'
+        -- recursion depth limited by the size of the record
+
+-- | SRV case - remove everyting and filter SRV records
+normalizeSrv :: String -> String -> NmcDom -> NmcDom
+normalizeSrv serv proto dom =
+  emptyNmcDom {domService = fmap (filter needed) (domService dom)}
+    where
+      needed r = srvName r == serv && srvProto r == proto
+
+-- | Presence of some elements require removal of some others
+normalizeDom :: NmcDom -> NmcDom
+normalizeDom dom = foldr id dom [ srvNormalizer
+                                , translateNormalizer
+                                , nsNormalizer
+                                ]
+  where
+    nsNormalizer dom = case domNs dom of
+      Nothing  -> dom
+      Just ns  -> emptyNmcDom { domNs = domNs dom, domEmail = domEmail dom }
+    translateNormalizer dom = case domTranslate dom of
+      Nothing  -> dom
+      Just tr  -> dom { domMap = Nothing }
+    srvNormalizer dom = dom { domService = Nothing, domMx = makemx }
+      where
+        makemx = case domService dom of
+          Nothing  -> Nothing
+          Just svl -> Just $ map makerec (filter needed svl)
+            where
+              needed sr = srvName sr == "smtp"
+                        && srvProto sr == "tcp"
+                        && srvPort sr == 25
+              makerec sr = (show (srvPrio sr)) ++ " " ++ (srvHost sr)
+
+-- | Merge imports and Selfs and follow the maps tree to get dom
+descendNmcDom ::
+  (String -> IO (Either String ByteString)) -- ^ query operation action
+  -> [String]                               -- ^ subdomain chain
+  -> NmcDom                                 -- ^ base domain
+  -> IO (Either String NmcDom)              -- ^ fully processed result
+descendNmcDom queryOp subdom base = do
+  base' <- mergeImport queryOp 10 base
+  case subdom of
+    []   -> return $ fmap normalizeDom base'
+    -- A hack to handle SRV records: don't descend if ["_prot","_serv"]
+    [('_':p),('_':s)] -> return $ fmap (normalizeSrv s p) base'
+    d:ds ->
+      case base' of
+        Left err     -> return base'
+        Right base'' ->
+          case domMap base'' of
+            Nothing  -> return $ Right emptyNmcDom
+            Just map ->
+              case lookup d map of
+                Nothing  -> return $ Right emptyNmcDom
+                Just sub -> descendNmcDom queryOp ds sub
+
+-- | Initial NmcDom populated with "import" only, suitable for "descend"
+seedNmcDom ::
+  String        -- ^ domain key (without namespace prefix)
+  -> NmcDom     -- ^ resulting seed domain
+seedNmcDom dn = emptyNmcDom { domImport = Just (["d/" ++ dn])}