Basic validation functions

[github/fretlink/hmacaroons.git] / src / Crypto / Macaroon / Verifier.hs

diff --git a/src/Crypto/Macaroon/Verifier.hs b/src/Crypto/Macaroon/Verifier.hs
index 012d156454f243f753c14547b4e908981fe3d61d..7d5f094f3fdf3d725bcb193460256ddb27263750 100644 (file)
--- a/src/Crypto/Macaroon/Verifier.hs
+++ b/src/Crypto/Macaroon/Verifier.hs
@@ -1,5 +1,8 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE FlexibleInstances    #-}
+{-# LANGUAGE OverloadedStrings    #-}
+{-# LANGUAGE RankNTypes           #-}
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
 {-|
 Module      : Crypto.Macaroon.Verifier
 Copyright   : (c) 2015 Julien Tanguy
@@ -13,62 +16,60 @@ Portability : portable
 
 -}
 module Crypto.Macaroon.Verifier (
-    Verified(..)
-  , verifySig
-  , verifyExact
-  , verifyFun
-  , verifyCavs
-  -- , module Data.Attoparsec.ByteString
-  , module Data.Attoparsec.ByteString.Char8
+    verify
+  , ValidationError(ValidatorError, ParseError)
+  -- , (.<), (.<=), (.==), (.>), (.>=)
+  -- , module Data.Attoparsec.ByteString.Char8
 ) where
 
 
-import           Crypto.Hash
+import           Control.Monad
+import           Control.Monad.IO.Class
+import           Data.Attoparsec.ByteString
+import           Data.Attoparsec.ByteString.Char8
 import           Data.Bool
-import qualified Data.ByteString            as BS
-import           Data.Byteable
-import           Data.Foldable
-import           Data.Maybe
-import Data.Attoparsec.ByteString
-import Data.Attoparsec.ByteString.Char8
+import qualified Data.ByteString                  as BS
+import           Data.Either.Combinators
 
 import           Crypto.Macaroon.Internal
+import           Crypto.Macaroon.Verifier.Internal
 
 
--- | Opaque datatype for now. Might need more explicit errors
-data Verified = Ok | Failed deriving (Show,Eq)
 
-instance Monoid Verified where
-  mempty = Ok
-  mappend Ok Ok = Ok
-  mappend _ _ = Failed
 
+-- (.<) :: (MonadIO m, Ord a, Parsable a) => Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- (.<) = verifyOpBool "Greater or equal" (<) "<"
 
-type CaveatVerifier = Caveat -> Maybe Verified
+-- (.<=) :: (MonadIO m, Ord a, Parsable a) => Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- (.<=) = verifyOpBool "Strictly greater" (<=) "<="
 
-verifySig :: Key -> Macaroon -> Verified
-verifySig k m = bool Failed Ok $
-      signature m == foldl' hash (toBytes (hmac derivedKey (identifier m) :: HMAC SHA256)) (caveats m)
-  where
-    hash s c = toBytes (hmac s (vid c `BS.append` cid c) :: HMAC SHA256)
-    derivedKey = toBytes (hmac "macaroons-key-generator" k :: HMAC SHA256)
+-- (.==) :: (MonadIO m, Eq a, Parsable a) => Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- (.==) = verifyOpBool "Not equal" (==) "="
+
+-- (.>) :: (MonadIO m, Ord a, Parsable a) => Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- (.>) = verifyOpBool "Less or equal" (>) ">"
+
+-- (.>=) :: (MonadIO m, Ord a, Parsable a) => Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- (.>=) = verifyOpBool "Strictly less" (>=) ">="
 
-verifyCavs :: [Caveat -> Maybe Verified] -> Macaroon -> Verified
-verifyCavs verifiers m = mconcat $ map (\c -> mconcat . catMaybes $ map ($ c) verifiers) (caveats m)
 
-verifyExact :: (Eq a) => Key -> a -> Parser a -> Caveat -> Maybe Verified
-verifyExact k expected = verifyFun k (expected ==)
+verify :: MonadIO m => Key -> [Caveat -> m (Maybe (Either ValidationError Caveat))] -> Macaroon -> m (Either ValidationError Macaroon)
+verify secret verifiers m = join <$> forM (verifySig secret m) (verifyCavs verifiers)
 
-verifyFun :: Key -> (a -> Bool) -> Parser a -> Caveat -> Maybe Verified
-verifyFun key f parser cav = if key `BS.isPrefixOf` cid cav then
-        case parseOnly kvparser (cid cav) of
-          Right v -> (bool Failed Ok . f) <$> Just v
-          Left _ -> Just Failed
-        else Nothing
+
+-- verifyOpBool :: MonadIO m => String -> Parser a -> (a -> a -> Bool) -> BS.ByteString -> Key -> m a -> Caveat -> m (Maybe (Either ValidationError Caveat))
+-- verifyOpBool err p f op k val = verifyParser k valueParser $ \s -> do
+--     expected <- val
+--     return $ bool (Left $ ValidatorError err) (Right Win) =<< f expected <$> mapLeft ParseError (parseOnly p s)
+--   where
+--     valueParser = string op *> skipSpace *> takeByteString
+
+verifyParser :: (MonadIO m) => Key -> Parser a -> (a -> m (Either ValidationError Win)) -> Caveat -> m (Maybe (Either ValidationError Caveat))
+verifyParser k p f c = case parseOnly keyParser . cid $ c of
+    Left _ -> return Nothing
+    Right bs -> Just <$> case parseOnly p bs of
+      Left err -> return $ Left $ ParseError err
+      Right a -> fmap (const c) <$> f a
   where
-    kvparser = do
-      key <- string key
-      skipSpace
-      string "="
-      skipSpace
-      parser <* endOfInput
+    keyParser = string k *> skipSpace *> takeByteString
+